diff --git a/me/smartstore/Main.java b/me/smartstore/Main.java
new file mode 100644
index 00000000..2f8a3d49
--- /dev/null
+++ b/me/smartstore/Main.java
@@ -0,0 +1,9 @@
+package me.smartstore;
+
+public class Main {
+    public static void main(String[] args) {
+        SmartStoreApp.getInstance().test().run();
+        //SmartStoreApp.getInstance().run();
+
+    }
+}
diff --git a/me/smartstore/SmartStoreApp.java b/me/smartstore/SmartStoreApp.java
new file mode 100644
index 00000000..c488f6e7
--- /dev/null
+++ b/me/smartstore/SmartStoreApp.java
@@ -0,0 +1,65 @@
+package me.smartstore;
+
+import me.smartstore.customer.Customer;
+import me.smartstore.customer.Customers;
+import me.smartstore.group.Group;
+import me.smartstore.group.GroupType;
+import me.smartstore.group.Groups;
+import me.smartstore.group.Parameter;
+import me.smartstore.menu.*;
+
+public class SmartStoreApp {
+    private final Groups allGroups = Groups.getInstance();
+    private final Customers allCustomers = Customers.getInstance();
+    private final MainMenu mainMenu = MainMenu.getInstance();
+
+    // singleton
+    private static SmartStoreApp smartStoreApp;
+
+    public static SmartStoreApp getInstance() {
+        if (smartStoreApp == null) {
+            smartStoreApp = new SmartStoreApp();
+        }
+        return smartStoreApp;
+    }
+
+    private SmartStoreApp() {}
+
+    public void details() {
+        System.out.println("\n\n===========================================");
+        System.out.println(" Title : SmartStore Customer Classification");
+        System.out.println(" Release Date : 23.04.27");
+        System.out.println(" Copyright 2023 Gyeongmin All rights reserved.");
+        System.out.println("===========================================\n");
+    }
+
+    public SmartStoreApp test() {
+        allGroups.add(new Group(new Parameter(10, 100000), GroupType.GENERAL));
+        allGroups.add(new Group(new Parameter(20, 200000), GroupType.VIP));
+        allGroups.add(new Group(new Parameter(30, 300000), GroupType.VVIP));
+
+        //고객 정보
+        for (int i = 0; i < 26; i++) {
+            allCustomers.add(new Customer(
+                    Character.toString(
+                            (char) ('a' + i)),
+                    (char) ('a' + i) + "123",
+                    ((int) (Math.random() * 5) + 1) * 10,
+                    ((int) (Math.random() * 5) + 1) * 100000));
+        }
+
+        System.out.println("allCustomers = " + allCustomers);
+        System.out.println("allGroups = " + allGroups);
+
+        // @TODO: refresh do not implemented yet.
+        allCustomers.refresh(allGroups);
+
+        return this; // smartStoreApp
+    }
+
+    public void run() {
+        details();
+        mainMenu.manage();
+
+    }
+}
\ No newline at end of file
diff --git a/me/smartstore/arrays/Collections.java b/me/smartstore/arrays/Collections.java
new file mode 100644
index 00000000..536be0a1
--- /dev/null
+++ b/me/smartstore/arrays/Collections.java
@@ -0,0 +1,16 @@
+package me.smartstore.arrays;
+
+public interface Collections<T> {
+    // 데이터를 가지고 있는 객체가 아님
+    // 구현 해야하는 메소드의 정보만 가지고 있음 (인터페이스)
+
+    int size();
+    T get(int index);
+    void set(int index, T object);
+    int indexOf(T object);
+    void add(T object);
+    void add(int index, T object);
+    T pop();
+    T pop(int index);
+    T pop(T object);
+}
\ No newline at end of file
diff --git a/me/smartstore/arrays/DArray.java b/me/smartstore/arrays/DArray.java
new file mode 100644
index 00000000..c9709002
--- /dev/null
+++ b/me/smartstore/arrays/DArray.java
@@ -0,0 +1,161 @@
+package me.smartstore.arrays;
+
+import me.smartstore.exception.ElementNotFoundException;
+import me.smartstore.exception.EmptyArrayException;
+import me.smartstore.exception.NullArgumentException;
+
+public class DArray<T> implements Collections<T> { // Dynamic Array
+    protected static final int DEFAULT = 10;
+
+    protected T[] arrays;
+    protected int size; //배열 원소의 개수
+    protected int capacity; //배열의 전체 크기
+
+    public DArray() throws ClassCastException {
+        arrays = (T[]) new Object[DEFAULT];
+        capacity = DEFAULT;
+    }
+
+    public DArray(int initial) throws ClassCastException {
+        arrays = (T[]) new Object[initial];
+        capacity = initial;
+    }
+
+    public DArray(T[] arrays) {
+        this.arrays = arrays;
+        capacity = arrays.length;
+        size = arrays.length;
+    }
+
+    /////////////////////////////////////////
+    // add, set, get, pop, indexOf, size, capacity (for dynamic-sized array)
+
+    @Override
+    public int size() {
+        return size;
+    }
+
+    // 배열에 얼마나 capacity 남아있는지 외부에 알려줄 필요가 없기 때문에 <protected>으로 정의
+    protected int capacity() {
+        return capacity;
+    }
+
+
+    //arrays의 index 위치에 있는 값을 반환
+    @Override
+    public T get(int index) throws IndexOutOfBoundsException {
+        if (index < 0 || index >= size) throw new IndexOutOfBoundsException();
+        return arrays[index];
+    }
+
+    /**
+     * @param: ...
+     * @return: ...
+     * @throws: IndexOutOfBoundsException
+     * @throws: NullArgumentException
+     * */
+    @Override
+    public void set(int index, T object) throws IndexOutOfBoundsException, NullArgumentException {
+        if (index < 0 || index >= size) throw new IndexOutOfBoundsException();
+        if (object == null) throw new NullArgumentException();
+
+        arrays[index] = object;
+    }
+
+
+    //object의 index를 반환
+    @Override
+    public int indexOf(T object) throws NullArgumentException, ElementNotFoundException {
+        if (object == null) throw new NullArgumentException(); // not found (instead of throwing exception)
+
+        for (int i = 0; i < size; i++) {
+            if (arrays[i] == null) continue;
+            if (arrays[i].equals(object)) return i;
+        }
+        throw new ElementNotFoundException(); // not found
+    }
+
+    // 배열의 cap이 부족한 경우
+    @Override
+    public void add(T object) throws NullArgumentException {
+        if (object == null) throw new NullArgumentException(); // if argument is null, do not add null value in array
+
+        if (size < capacity) {
+            arrays[size] = object;
+            size++;
+        } else {
+            grow();
+            add(object);
+        }
+    }
+
+    //원하는 index 위치로 데이터 넣기
+    @Override
+    public void add(int index, T object) throws IndexOutOfBoundsException, NullArgumentException {
+        if (index < 0 || index >= size) throw new IndexOutOfBoundsException();
+        if (object == null) throw new NullArgumentException();
+
+        if (size < capacity) {
+            for (int i = size-1; i >= index ; i--) {
+                arrays[i+1] = arrays[i];
+            }
+            arrays[index] = object;
+            size++;
+        } else {
+            grow();
+            add(index, object);
+        }
+    }
+
+
+    //배열의 맨 끝 원소 pop
+    @Override
+    public T pop() {
+//        if (size == 0) return null;
+//
+//        T popElement = arrays[size-1];
+//        arrays[size-1] = null;
+//        size--;
+//        return popElement;
+        return pop(size-1);
+    }
+
+    //index의 원소 pop
+    @Override
+    public T pop(int index) throws IndexOutOfBoundsException {
+        if (size == 0) throw new EmptyArrayException();
+        if (index < 0 || index >= size) throw new IndexOutOfBoundsException();
+
+        T popElement = arrays[index];
+        arrays[index] = null; // 삭제됨을 명시적으로 표현
+
+        for (int i = index+1; i < size; i++) {
+            arrays[i-1] = arrays[i];
+        }
+        arrays[size-1] = null;
+        size--;
+        return popElement;
+    }
+
+    //원하는 데이터 pop
+    @Override
+    public T pop(T object) {
+        return pop(indexOf(object));
+    }
+
+    protected void grow() {
+        capacity *= 2; // doubling
+        arrays = java.util.Arrays.copyOf(arrays, capacity);
+
+        // size는 그대로
+    }
+
+    @Override
+    public String toString() {
+        String toStr = "";
+        for (int i = 0; i < size; i++) {
+            toStr += (arrays[i] + "\n");
+        }
+        return toStr;
+    }
+}
\ No newline at end of file
diff --git a/me/smartstore/customer/Customer.java b/me/smartstore/customer/Customer.java
new file mode 100644
index 00000000..1a30c3a5
--- /dev/null
+++ b/me/smartstore/customer/Customer.java
@@ -0,0 +1,94 @@
+package me.smartstore.customer;
+
+import me.smartstore.group.Group;
+import java.util.Objects;
+
+public class Customer {
+    private String cusName;
+    private String cusId;
+    private Integer cusTotalTime; //총 이용 시간
+    private Integer cusTotalPay; //총 이용 금액
+    private Group group;
+
+    public Customer(){}
+
+    public Customer(String cusId) {
+        this.cusId = cusId;
+    }
+
+    public Customer(String cusName, String cusId) {
+        this.cusName = cusName;
+        this.cusId = cusId;
+    }
+
+    public Customer(String cusName, String cusId, Integer cusTotalTime, Integer cusTotalPay) {
+        this.cusName = cusName;
+        this.cusId = cusId;
+        this.cusTotalTime = cusTotalTime;
+        this.cusTotalPay = cusTotalPay;
+    }
+
+    public String getCusName() {
+        return cusName;
+    }
+
+    public void setCusName(String cusName) {
+        this.cusName = cusName;
+    }
+
+    public String getCusId() {
+        return cusId;
+    }
+
+    public void setCusId(String cusId) {
+        this.cusId = cusId;
+    }
+
+    public Integer getCusTotalTime() {
+        return cusTotalTime;
+    }
+
+    public void setCusTotalTime(Integer cusTotalTime) {
+        this.cusTotalTime = cusTotalTime;
+    }
+
+    public Integer getCusTotalPay() {
+        return cusTotalPay;
+    }
+
+    public void setCusTotalPay(Integer cusTotalPay) {
+        this.cusTotalPay = cusTotalPay;
+    }
+
+    public Group getGroup() {
+        return group;
+    }
+
+    public void setGroup(Group group) {
+        this.group = group;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        Customer customer = (Customer) o;
+        return Objects.equals(cusId, customer.cusId);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(cusId);
+    }
+
+    @Override
+    public String toString() {
+        return "Customer{" +
+                "cusName='" + cusName + '\'' +
+                ", cusId='" + cusId + '\'' +
+                ", cusTotalTime=" + cusTotalTime +
+                ", cusTotalPay=" + cusTotalPay +
+                ", group=" + group +
+                '}';
+    }
+}
diff --git a/me/smartstore/customer/Customers.java b/me/smartstore/customer/Customers.java
new file mode 100644
index 00000000..46cd91d8
--- /dev/null
+++ b/me/smartstore/customer/Customers.java
@@ -0,0 +1,40 @@
+package me.smartstore.customer;
+
+import me.smartstore.arrays.DArray;
+import me.smartstore.group.Groups;
+
+public class Customers extends DArray<Customer>{
+
+    //singleton
+    private static Customers allCustomers;
+
+    private final Groups allGroups = Groups.getInstance();
+
+    public static Customers getInstance(){
+        if(allCustomers == null)
+            allCustomers = new Customers();
+        return allCustomers;
+    }
+
+    private Customers(){}
+
+    //refresh 함수가 호출되는 경우
+    //1. 분류기준이 바뀔 때
+    //2. 새로운 고객이 들어올 때
+    public void refresh(Groups groups){
+        for(int i = 0; i < allCustomers.size(); i++){
+            try{
+                for(int j = 0; j < groups.size(); j++){
+                    if(allCustomers.get(i).getCusTotalTime() >= groups.get(j).getParameter().getMinTime()
+                            && allCustomers.get(i).getCusTotalPay() >= groups.get(j).getParameter().getMinPay()){
+                        allCustomers.get(i).setGroup(groups.get(j));
+                    }
+                }
+            }catch (NullPointerException e){
+                continue;
+            }
+
+        }
+    }
+
+}
diff --git a/me/smartstore/exception/ArrayEmptyException.java b/me/smartstore/exception/ArrayEmptyException.java
new file mode 100644
index 00000000..8acc24f4
--- /dev/null
+++ b/me/smartstore/exception/ArrayEmptyException.java
@@ -0,0 +1,13 @@
+package me.smartstore.exception;
+
+import me.smartstore.util.Message;
+public class ArrayEmptyException extends RuntimeException {
+
+    public ArrayEmptyException() {
+        super(Message.ERR_MSG_INVALID_ARR_EMPTY);
+    }
+
+    public ArrayEmptyException(String message) {
+        super(message);
+    }
+}
\ No newline at end of file
diff --git a/me/smartstore/exception/ElementNotFoundException.java b/me/smartstore/exception/ElementNotFoundException.java
new file mode 100644
index 00000000..efe992f5
--- /dev/null
+++ b/me/smartstore/exception/ElementNotFoundException.java
@@ -0,0 +1,22 @@
+package me.smartstore.exception;
+
+public class ElementNotFoundException extends RuntimeException {
+    public ElementNotFoundException() {
+    }
+
+    public ElementNotFoundException(String message) {
+        super(message);
+    }
+
+    public ElementNotFoundException(String message, Throwable cause) {
+        super(message, cause);
+    }
+
+    public ElementNotFoundException(Throwable cause) {
+        super(cause);
+    }
+
+    public ElementNotFoundException(String message, Throwable cause, boolean enableSuppression, boolean writableStackTrace) {
+        super(message, cause, enableSuppression, writableStackTrace);
+    }
+}
\ No newline at end of file
diff --git a/me/smartstore/exception/EmptyArrayException.java b/me/smartstore/exception/EmptyArrayException.java
new file mode 100644
index 00000000..af00e9f5
--- /dev/null
+++ b/me/smartstore/exception/EmptyArrayException.java
@@ -0,0 +1,22 @@
+package me.smartstore.exception;
+
+public class EmptyArrayException extends RuntimeException {
+    public EmptyArrayException() {
+    }
+
+    public EmptyArrayException(String message) {
+        super(message);
+    }
+
+    public EmptyArrayException(String message, Throwable cause) {
+        super(message, cause);
+    }
+
+    public EmptyArrayException(Throwable cause) {
+        super(cause);
+    }
+
+    public EmptyArrayException(String message, Throwable cause, boolean enableSuppression, boolean writableStackTrace) {
+        super(message, cause, enableSuppression, writableStackTrace);
+    }
+}
\ No newline at end of file
diff --git a/me/smartstore/exception/InputEmptyException.java b/me/smartstore/exception/InputEmptyException.java
new file mode 100644
index 00000000..8ea30894
--- /dev/null
+++ b/me/smartstore/exception/InputEmptyException.java
@@ -0,0 +1,14 @@
+package me.smartstore.exception;
+
+import me.smartstore.util.Message;
+
+public class InputEmptyException extends RuntimeException {
+
+    public InputEmptyException() {
+        super(Message.ERR_MSG_INVALID_INPUT_EMPTY);
+    }
+
+    public InputEmptyException(String message) {
+        super(message);
+    }
+}
\ No newline at end of file
diff --git a/me/smartstore/exception/InputEndException.java b/me/smartstore/exception/InputEndException.java
new file mode 100644
index 00000000..af902e83
--- /dev/null
+++ b/me/smartstore/exception/InputEndException.java
@@ -0,0 +1,13 @@
+package me.smartstore.exception;
+
+import me.smartstore.util.Message;
+
+public class InputEndException extends RuntimeException {
+    public InputEndException() {
+        super(Message.ERR_MSG_INPUT_END);
+    }
+
+    public InputEndException(String message) {
+        super(message);
+    }
+}
\ No newline at end of file
diff --git a/me/smartstore/exception/InputFormatException.java b/me/smartstore/exception/InputFormatException.java
new file mode 100644
index 00000000..49a76220
--- /dev/null
+++ b/me/smartstore/exception/InputFormatException.java
@@ -0,0 +1,13 @@
+package me.smartstore.exception;
+
+import me.smartstore.util.Message;
+
+public class InputFormatException extends RuntimeException {
+    public InputFormatException() {
+        super(Message.ERR_MSG_INVALID_INPUT_FORMAT);
+    }
+
+    public InputFormatException(String message) {
+        super(message);
+    }
+}
\ No newline at end of file
diff --git a/me/smartstore/exception/InputRangeException.java b/me/smartstore/exception/InputRangeException.java
new file mode 100644
index 00000000..10d7b011
--- /dev/null
+++ b/me/smartstore/exception/InputRangeException.java
@@ -0,0 +1,13 @@
+package me.smartstore.exception;
+
+import me.smartstore.util.Message;
+
+public class InputRangeException extends RuntimeException {
+    public InputRangeException() {
+        super(Message.ERR_MSG_INVALID_INPUT_RANGE);
+    }
+
+    public InputRangeException(String message) {
+        super(message);
+    }
+}
diff --git a/me/smartstore/exception/InputTypeException.java b/me/smartstore/exception/InputTypeException.java
new file mode 100644
index 00000000..0226f9c3
--- /dev/null
+++ b/me/smartstore/exception/InputTypeException.java
@@ -0,0 +1,13 @@
+package me.smartstore.exception;
+
+import me.smartstore.util.Message;
+
+public class InputTypeException extends RuntimeException {
+    public InputTypeException() {
+        super(Message.ERR_MSG_INVALID_INPUT_TYPE);
+    }
+
+    public InputTypeException(String message) {
+        super(message);
+    }
+}
diff --git a/me/smartstore/exception/NullArgumentException.java b/me/smartstore/exception/NullArgumentException.java
new file mode 100644
index 00000000..15f03cd5
--- /dev/null
+++ b/me/smartstore/exception/NullArgumentException.java
@@ -0,0 +1,22 @@
+package me.smartstore.exception;
+
+public class NullArgumentException extends RuntimeException {
+    public NullArgumentException() {
+    }
+
+    public NullArgumentException(String message) {
+        super(message);
+    }
+
+    public NullArgumentException(String message, Throwable cause) {
+        super(message, cause);
+    }
+
+    public NullArgumentException(Throwable cause) {
+        super(cause);
+    }
+
+    public NullArgumentException(String message, Throwable cause, boolean enableSuppression, boolean writableStackTrace) {
+        super(message, cause, enableSuppression, writableStackTrace);
+    }
+}
\ No newline at end of file
diff --git a/me/smartstore/group/Group.java b/me/smartstore/group/Group.java
new file mode 100644
index 00000000..633e1cee
--- /dev/null
+++ b/me/smartstore/group/Group.java
@@ -0,0 +1,53 @@
+package me.smartstore.group;
+
+import java.util.Objects;
+
+public class Group {
+    private Parameter parameter; //분류 기준
+    private GroupType groupType;
+
+    public Group(){}
+
+    public Group(Parameter parameter, GroupType groupType) {
+        this.parameter = parameter;
+        this.groupType = groupType;
+    }
+
+
+    public Parameter getParameter() {
+        return parameter;
+    }
+
+    public void setParameter(Parameter parameter) {
+        this.parameter = parameter;
+    }
+
+    public GroupType getGroupType() {
+        return groupType;
+    }
+
+    public void setGroupType(GroupType groupType) {
+        this.groupType = groupType;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        Group group = (Group) o;
+        return Objects.equals(parameter, group.parameter) && groupType == group.groupType;
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(parameter, groupType);
+    }
+
+    @Override
+    public String toString() {
+        return "Group{" +
+                "parameter=" + parameter +
+                ", groupType=" + groupType +
+                '}';
+    }
+}
diff --git a/me/smartstore/group/GroupType.java b/me/smartstore/group/GroupType.java
new file mode 100644
index 00000000..33eadabe
--- /dev/null
+++ b/me/smartstore/group/GroupType.java
@@ -0,0 +1,25 @@
+package me.smartstore.group;
+
+public enum GroupType {
+    N("해당없음"), G("일반고객"), V("우수고객"), VV("최우수고객"),
+    NONE("해당없음"), GENERAL("일반고객"), VIP("우수고객"), VVIP("최우수고객");
+
+    String groupType = "";
+
+    GroupType(String groupType) {
+        this.groupType = groupType;
+    }
+
+    public GroupType replaceFullName(){
+        if(this == N)
+            return NONE;
+        else if(this == G)
+            return GENERAL;
+        else if(this == V)
+            return VIP;
+        else if(this == VV)
+            return VVIP;
+
+        return this;
+    }
+}
diff --git a/me/smartstore/group/Groups.java b/me/smartstore/group/Groups.java
new file mode 100644
index 00000000..6022556f
--- /dev/null
+++ b/me/smartstore/group/Groups.java
@@ -0,0 +1,31 @@
+package me.smartstore.group;
+
+import me.smartstore.arrays.DArray;
+
+public class Groups extends DArray<Group> {
+    private static Groups allGroups;
+
+    public static Groups getInstance(){
+        if(allGroups == null)
+            allGroups = new Groups();
+        return allGroups;
+    }
+
+    private Groups(){}
+
+    public Group find(GroupType groupType){
+        for(int i = 0; i < allGroups.size(); i++){
+            if(allGroups.get(i).getGroupType() == groupType){
+                return allGroups.get(i);
+            }
+        }
+//        for(Group group : arrays){
+//            if(group.getGroupType() == groupType){ //enum의 비교는 equals가 아님 -> 상수이기 때문
+//                return group;
+//            }
+//        }
+
+        return null;
+
+    }
+}
diff --git a/me/smartstore/group/Parameter.java b/me/smartstore/group/Parameter.java
new file mode 100644
index 00000000..0622a4fe
--- /dev/null
+++ b/me/smartstore/group/Parameter.java
@@ -0,0 +1,52 @@
+package me.smartstore.group;
+
+import java.util.Objects;
+
+public class Parameter {
+    private Integer minTime;
+    private Integer minPay;
+
+    public Parameter(){}
+
+    public Parameter(Integer minTime, Integer minPay) {
+        this.minTime = minTime;
+        this.minPay = minPay;
+    }
+
+    public Integer getMinTime() {
+        return minTime;
+    }
+
+    public void setMinTime(Integer minTime) {
+        this.minTime = minTime;
+    }
+
+    public Integer getMinPay() {
+        return minPay;
+    }
+
+    public void setMinPay(Integer minPay) {
+        this.minPay = minPay;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        Parameter parameter = (Parameter) o;
+        return Objects.equals(minTime, parameter.minTime) && Objects.equals(minPay, parameter.minPay);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(minTime, minPay);
+    }
+
+    @Override
+    public String toString() {
+        return "Parameter{" +
+                "minTime=" + minTime +
+                ", minPay=" + minPay +
+                '}';
+    }
+}
diff --git a/me/smartstore/menu/CustomerMenu.java b/me/smartstore/menu/CustomerMenu.java
new file mode 100644
index 00000000..b51af811
--- /dev/null
+++ b/me/smartstore/menu/CustomerMenu.java
@@ -0,0 +1,156 @@
+package me.smartstore.menu;
+
+import me.smartstore.customer.Customer;
+import me.smartstore.customer.Customers;
+import me.smartstore.exception.InputEndException;
+import me.smartstore.group.Groups;
+import me.smartstore.util.Message;
+
+import java.util.Scanner;
+
+public class CustomerMenu implements Menu{
+
+    //singleton
+    private static CustomerMenu customerMenu;
+
+    private final Customers allCustomers = Customers.getInstance();
+    private final Groups allGroups = Groups.getInstance();
+
+    Scanner sc = new Scanner(System.in);
+
+    public static CustomerMenu getInstance(){
+        if(customerMenu == null)
+            customerMenu = new CustomerMenu();
+        return customerMenu;
+    }
+
+    private CustomerMenu(){}
+
+    @Override
+    public void manage() {
+        while( true ){
+            int choice = chooseMenu(new String[]{
+                    "Add Customer",
+                    "View Customer",
+                    "Update Customer",
+                    "Delete Customer",
+                    "Back"});
+
+            if(choice == 1)
+                addCustomer();
+            else if(choice == 2)
+               viewCustomer();
+           else if(choice == 3)
+               updateCustomer();
+           else if(choice == 4)
+                deleteCustomer();
+           else break; // choice == 5
+       }
+    }
+
+
+    public void addCustomer() {
+        while(true){
+            try{
+                System.out.println("How many customers to input?");
+                int n = Integer.parseInt(nextLine(Message.END_MSG));
+
+                for(int i = 0; i < n; i++){
+                    System.out.println("===============");
+                    System.out.println("User" + (i + 1) + " info");
+                    System.out.println("===============");
+                    Customer customer = new Customer();
+                    chooseCustomerInfo(customer);
+                    allCustomers.add(customer);
+
+                }
+
+                allCustomers.refresh(allGroups);
+                break;
+
+            }catch (InputEndException e){
+                System.out.println(Message.ERR_MSG_INPUT_END);
+                break;
+            }catch (NumberFormatException e){
+                System.out.println(Message.ERR_MSG_INVALID_INPUT_FORMAT);
+            }
+        }
+
+
+    }
+
+    public void viewCustomer(){
+        System.out.println(allCustomers);
+    }
+
+    public void updateCustomer(){
+        chooseCustomerInfo(allCustomers.get(pickCustomer()));
+
+        allCustomers.refresh(allGroups);
+    }
+
+    private void deleteCustomer() {
+       Customer customer = allCustomers.pop(pickCustomer());
+    }
+
+    public int pickCustomer() {
+        for (int i = 0; i < allCustomers.size(); i++) {
+            System.out.println("No. " + (i + 1) + " => " + allCustomers.get(i));
+        }
+        while(true){
+            try {
+                System.out.print("Which customer ( 1 ~ " + allCustomers.size() + " )? ");
+                int n = Integer.parseInt(nextLine());
+
+                if(n > allCustomers.size()){
+                    System.out.println("Index Out of Bounds. Please try again.");
+                    continue;
+                }
+
+                return n;
+            } catch (NumberFormatException e) {
+                System.out.println(Message.ERR_MSG_INVALID_INPUT_FORMAT);
+            }
+        }
+
+    }
+
+    public void chooseCustomerInfo(Customer customer){
+        while( true ){
+            try{
+                int choice = chooseMenu(new String[]{
+                        "Customer Name",
+                        "Customer ID",
+                        "Customer Spent Time",
+                        "Customer Total Pay",
+                        "Back"});
+
+                if(choice == 1){
+                    System.out.println("Input Customer's name:");
+                    String name = nextLine(Message.END_MSG);
+                    customer.setCusName(name);
+                }
+                else if(choice == 2){
+                    System.out.println("'Input Customer's ID:");
+                    String id = nextLine(Message.END_MSG);
+                    customer.setCusId(id);
+                }
+                else if(choice == 3){
+                    System.out.println("'Input Customer's Spent Time:");
+                    int spentTime = Integer.parseInt(nextLine(Message.END_MSG));
+                    customer.setCusTotalTime(spentTime);
+                }
+                else if(choice == 4){
+                    System.out.println("'Input Customer's Total Pay:");
+                    int totalPay = Integer.parseInt(nextLine(Message.END_MSG));
+                    customer.setCusTotalPay(totalPay);
+                }
+                else break; // choice == 5
+            }catch (InputEndException e){
+                System.out.println(Message.ERR_MSG_INPUT_END);
+            }
+
+        }
+
+    }
+}
diff --git a/me/smartstore/menu/GroupMenu.java b/me/smartstore/menu/GroupMenu.java
new file mode 100644
index 00000000..3c055bc7
--- /dev/null
+++ b/me/smartstore/menu/GroupMenu.java
@@ -0,0 +1,171 @@
+package me.smartstore.menu;
+
+import me.smartstore.customer.Customers;
+import me.smartstore.exception.InputEndException;
+import me.smartstore.exception.InputTypeException;
+import me.smartstore.group.Group;
+import me.smartstore.group.GroupType;
+import me.smartstore.group.Groups;
+import me.smartstore.group.Parameter;
+import me.smartstore.util.Message;
+
+public class GroupMenu implements Menu {
+    private final Groups allGroups = Groups.getInstance();
+    private final Customers allCustomers = Customers.getInstance();
+
+    //singleton
+    private static GroupMenu groupMenu;
+
+    public static GroupMenu getInstance() {
+        if (groupMenu == null)
+            groupMenu = new GroupMenu();
+        return groupMenu;
+    }
+
+    private GroupMenu() {
+    }
+
+    @Override
+    public void manage() {
+        while (true) {
+            int choice = chooseMenu(new String[]{
+                    "Set Parameter",
+                    "View Parameter",
+                    "Update Parameter",
+                    "Back"});
+
+            if (choice == 1)
+                setParameter();
+            else if (choice == 2)
+                viewParameter();
+            else if (choice == 3)
+                updateParameter();
+            else break; // choice == 4
+        }
+    }
+
+    public GroupType chooseGroup() {
+        while (true) {
+            try {
+                System.out.println("Which Group (GENERAL (G), VIP (V), VVIP (VV)? ");
+                String choice = nextLine(Message.END_MSG);
+
+                GroupType groupType = GroupType.valueOf(choice).replaceFullName();
+                return groupType;
+            } catch (InputEndException e) {
+                System.out.println(Message.ERR_MSG_INPUT_END);
+                break;
+            } catch (IllegalArgumentException e) {
+                System.out.println(Message.ERR_MSG_INVALID_INPUT_RANGE);
+            }
+        }
+        return null;
+    }
+
+    public void setParameter() {
+        while (true) {
+            GroupType groupType = chooseGroup();
+
+            Group group = allGroups.find(groupType);
+            if (group != null && group.getGroupType() != null) {
+                System.out.println("\n" + group.getGroupType() + "group already exists.");
+                System.out.println("\n" + group);
+            } else if(group == null){
+                return;
+            }else {
+                Parameter parameter = new Parameter();
+                //time, pay 사용자 입력받은 후, 설정 필요
+
+                group.setParameter(parameter);
+                allCustomers.refresh(allGroups);
+            }
+        }
+    }
+
+    public void viewParameter() {
+        while (true) {
+            GroupType groupType = chooseGroup();
+
+            Group group = allGroups.find(groupType);
+            if (group == null || group.getGroupType() == null)
+                break;
+            else {
+                System.out.println("\n" + group.getGroupType());
+                System.out.println("\n" + group);
+            }
+        }
+    }
+
+    public void updateParameter() {
+        while (true) {
+            GroupType groupType = chooseGroup();
+
+            Group group = allGroups.find(groupType);
+            if (group == null || group.getGroupType() == null)
+                return;
+            else {
+                chooseParameter(group);
+            }
+        }
+
+    }
+
+    public void chooseParameter(Group group){
+        while( true ){
+            int choice = chooseMenu(new String[]{
+                    "Minimum Spent Time",
+                    "Minimum Total Pay",
+                    "Back"});
+            try{
+                if (choice == 1) {
+                    inputTime(group);
+                    allCustomers.refresh(allGroups);
+                }else if ( choice == 2){
+                    inputPay(group);
+                    allCustomers.refresh(allGroups);
+                }else {
+                    System.out.println(group.toString());
+                    break; //choice == 3
+                }
+            }catch (InputTypeException e) {
+                System.out.println(Message.ERR_MSG_INVALID_INPUT_TYPE);
+            }
+        }
+    }
+
+    public int inputTime(Group group){
+        int minTime = 0;
+        while(true){
+            try{
+                System.out.println("Input Minimum Spent Time: ");
+                minTime = Integer.parseInt(nextLine(Message.END_MSG));
+            }catch (InputTypeException e){
+                System.out.println(Message.ERR_MSG_INVALID_INPUT_TYPE);
+            }catch (NumberFormatException e){
+                System.out.println(Message.ERR_MSG_INVALID_INPUT_FORMAT);
+            }catch (InputEndException e){
+                System.out.println(Message.ERR_MSG_INPUT_END);
+                break;
+            }
+        }
+        return minTime;
+    }
+
+    public int inputPay(Group group){
+        int totalPay = 0;
+        while(true){
+            try{
+                System.out.println("Input Minimum Total pay: ");
+                totalPay = Integer.parseInt(nextLine(Message.END_MSG));
+            }catch (InputTypeException e){
+                System.out.println(Message.ERR_MSG_INVALID_INPUT_TYPE);
+            }catch (NumberFormatException e){
+                System.out.println(Message.ERR_MSG_INVALID_INPUT_FORMAT);
+            }catch (InputEndException e){
+                System.out.println(Message.ERR_MSG_INPUT_END);
+                break;
+            }
+        }
+        return totalPay;
+    }
+}
\ No newline at end of file
diff --git a/me/smartstore/menu/MainMenu.java b/me/smartstore/menu/MainMenu.java
new file mode 100644
index 00000000..952ead3c
--- /dev/null
+++ b/me/smartstore/menu/MainMenu.java
@@ -0,0 +1,41 @@
+package me.smartstore.menu;
+
+public class MainMenu implements Menu{
+    private final CustomerMenu customerMenu = CustomerMenu.getInstance();
+    private final GroupMenu groupMenu = GroupMenu.getInstance();
+    private final SummaryMenu summaryMenu = SummaryMenu.getInstance();
+
+    //singleton
+    private static MainMenu mainMenu;
+
+    public static MainMenu getInstance(){
+        if(mainMenu == null)
+            mainMenu = new MainMenu();
+        return mainMenu;
+    }
+
+    private MainMenu(){}
+
+
+    @Override
+    public void manage() {
+        while ( true ){
+            int choice = chooseMenu(new String[]{
+                    "Parameter",
+                    "Customer",
+                    "Classification Summary",
+                    "Quit"});
+
+            if(choice == 1)
+                groupMenu.manage();
+            else if(choice == 2)
+                customerMenu.manage();
+            else if(choice == 3)
+                summaryMenu.manage();
+            else{
+                System.out.println("Program Finished");
+                break;
+            }
+        }
+    }
+}
diff --git a/me/smartstore/menu/Menu.java b/me/smartstore/menu/Menu.java
new file mode 100644
index 00000000..b5805ddd
--- /dev/null
+++ b/me/smartstore/menu/Menu.java
@@ -0,0 +1,49 @@
+package me.smartstore.menu;
+
+import me.smartstore.exception.InputEndException;
+import me.smartstore.exception.InputRangeException;
+import me.smartstore.util.Message;
+
+import java.util.Scanner;
+
+public interface Menu {
+    Scanner sc = new Scanner(System.in);
+
+    default String nextLine(){
+        return sc.nextLine().toUpperCase();
+
+    }
+
+    default String nextLine(String end){
+        System.out.println("** Press 'end', if you want to exit! **");
+        String str = nextLine().toUpperCase();
+        if(str.equals(end)) throw new InputEndException();
+        return str;
+
+    }
+
+    default int chooseMenu(String[] menus){
+        while( true ){
+            try{
+                System.out.println("==============================");
+                for(int i = 0; i < menus.length; i++){
+                    System.out.printf(" %d. %s\n", i + 1, menus[i]);
+                }
+                System.out.println("==============================");
+                System.out.print("Choose one: ");
+                int choice = Integer.parseInt(nextLine());
+                if(choice >= 1 && choice <= menus.length)
+                    return choice;
+                throw new InputRangeException(); //choice 범위 초과
+
+            } catch (InputRangeException e){
+                System.out.println(Message.ERR_MSG_INVALID_INPUT_RANGE);
+            } catch (NumberFormatException e){
+                System.out.println(Message.ERR_MSG_INVALID_INPUT_FORMAT);
+            }
+        }
+    }
+
+    //각 서브 메뉴들을 관리하는 메소드
+    void manage();
+}
diff --git a/me/smartstore/menu/SummaryMenu.java b/me/smartstore/menu/SummaryMenu.java
new file mode 100644
index 00000000..100f9584
--- /dev/null
+++ b/me/smartstore/menu/SummaryMenu.java
@@ -0,0 +1,257 @@
+package me.smartstore.menu;
+
+import me.smartstore.customer.Customer;
+import me.smartstore.customer.Customers;
+import me.smartstore.exception.InputEndException;
+import me.smartstore.exception.InputTypeException;
+import me.smartstore.group.Group;
+import me.smartstore.group.Groups;
+import me.smartstore.util.Message;
+
+import java.util.Arrays;
+import java.util.Comparator;
+
+public class SummaryMenu implements Menu {
+
+    //singleton
+    private static SummaryMenu summaryMenu;
+
+    private final Groups allGroups = Groups.getInstance();
+    private final Customers allCustomers = Customers.getInstance();
+
+    public static SummaryMenu getInstance(){
+        if(summaryMenu == null)
+            summaryMenu = new SummaryMenu();
+        return summaryMenu;
+    }
+
+    private SummaryMenu(){}
+
+    @Override
+    public void manage() {
+        while ( true ){
+            int choice = chooseMenu(new String[]{
+                    "Summary",
+                    "Summary (Sorted By Name)",
+                    "Summary (Sorted By Time)",
+                    "Summary (Sorted By Pay)",
+                    "Back"});
+
+            if(choice == 1)
+                summary();
+            else if(choice == 2)
+                summaryByName();
+            else if(choice == 3)
+                summaryByTime();
+            else if(choice == 4)
+                summaryByPay();
+            else break; // choice == 5
+        }
+    }
+
+    public void summary(){
+        Customer[] customers = toArray();
+        for(int i = 0; i < allGroups.size(); i++){
+            Group group = allGroups.get(i);
+            System.out.println("==============================");
+            System.out.println("Group : " + group.getGroupType() +
+                    " ( Time : " + group.getParameter().getMinTime() + ", Pay : "
+                    + group.getParameter().getMinPay() + " )");
+            System.out.println("==============================");
+
+            for(int j = 0; j < customers.length; j++){
+                if(allGroups.get(i).getGroupType().equals(customers[j].getGroup().getGroupType())){
+                    System.out.println("No. " + (j + 1) + " => " + customers[j]);
+                }
+            }
+        }
+    }
+
+    public void summaryByName(){
+        Customer[] customers = toArray();
+        String order = "";
+        while(true){
+            System.out.println("Which order (ASCENDING (A), DESCENDING (D))?");
+            try{
+                order = nextLine(Message.END_MSG);
+
+                if(order.equals("A")){
+                    Arrays.sort(customers, new Comparator<Customer>() {
+                        @Override
+                        public int compare(Customer o1, Customer o2) {
+                            return o1.getCusName().compareTo(o2.getCusName());
+                        }
+                    });
+
+                    for(int i = 0; i < allGroups.size(); i++){
+                        Group group = allGroups.get(i);
+                        System.out.println("==============================");
+                        System.out.println("Group : " + group.getGroupType() +
+                                " ( Time : " + group.getParameter().getMinTime() + ", Pay : "
+                                + group.getParameter().getMinPay() + " )");
+                        System.out.println("==============================");
+
+                        for(int j = 0; j < customers.length; j++){
+                            if(allGroups.get(i).getGroupType().equals(customers[j].getGroup().getGroupType())){
+                                System.out.println("No. " + (j + 1) + " => " + customers[j]);
+                            }
+                        }
+                    }
+                }
+
+                if(order.equals("D")){
+                    Arrays.sort(customers, new Comparator<Customer>() {
+                        @Override
+                        public int compare(Customer o1, Customer o2) {
+                            return o1.getCusName().compareTo(o2.getCusName()) * -1;
+                        }
+                    });
+
+                    for(int i = 0; i < allGroups.size(); i++){
+                        Group group = allGroups.get(i);
+                        System.out.println("==============================");
+                        System.out.println("Group : " + group.getGroupType() +
+                                " ( Time : " + group.getParameter().getMinTime() + ", Pay : "
+                                + group.getParameter().getMinPay() + " )");
+                        System.out.println("==============================");
+
+                        for(int j = 0; j < customers.length; j++){
+                            if(allGroups.get(i).getGroupType().equals(customers[j].getGroup().getGroupType())){
+                                System.out.println("No. " + (j + 1) + " => " + customers[j]);
+                            }
+                        }
+                    }
+                }
+
+            }catch (InputEndException e){
+                System.out.println(Message.ERR_MSG_INPUT_END);
+                break;
+            }
+        }
+
+
+
+    }
+
+    private void summaryByTime() {
+        Customer[] customers = toArray();
+        String order = "";
+        while(true){
+            System.out.println("Which order (ASCENDING (A), DESCENDING (D))?");
+            try{
+                order = nextLine(Message.END_MSG);
+
+                if(order.equals("A")){
+                    Arrays.sort(customers, new Comparator<Customer>() {
+                        @Override
+                        public int compare(Customer o1, Customer o2) {
+                            return o1.getCusTotalTime().compareTo(o2.getCusTotalTime());
+                        }
+                    });
+
+                    for(int i = 0; i < allGroups.size(); i++){
+                        Group group = allGroups.get(i);
+                        System.out.println("==============================");
+                        System.out.println("Group : " + group.getGroupType() +
+                                " ( Time : " + group.getParameter().getMinTime() + ", Pay : "
+                                + group.getParameter().getMinPay() + " )");
+                        System.out.println("==============================");
+
+                        for(int j = 0; j < customers.length; j++){
+                            if(allGroups.get(i).getGroupType().equals(customers[j].getGroup().getGroupType())){
+                                System.out.println("No. " + (j + 1) + " => " + customers[j]);
+                            }
+                        }
+                    }
+                }
+
+                if(order.equals("D")) {
+                    Arrays.sort(customers, new Comparator<Customer>() {
+                        @Override
+                        public int compare(Customer o1, Customer o2) {
+                            return o1.getCusTotalTime().compareTo(o2.getCusTotalTime()) * -1;
+                        }
+                    });
+
+                    for(int i = 0; i < allGroups.size(); i++){
+                        Group group = allGroups.get(i);
+                        System.out.println("==============================");
+                        System.out.println("Group : " + group.getGroupType() +
+                                " ( Time : " + group.getParameter().getMinTime() + ", Pay : "
+                                + group.getParameter().getMinPay() + " )");
+                        System.out.println("==============================");
+
+                        for(int j = 0; j < customers.length; j++){
+                            if(allGroups.get(i).getGroupType().equals(customers[j].getGroup().getGroupType())){
+                                System.out.println("No. " + (j + 1) + " => " + customers[j]);
+                            }
+                        }
+                    }
+                }
+
+            }catch (InputEndException e){
+                System.out.println(Message.ERR_MSG_INPUT_END);
+                break;
+            }
+
+
+        }
+
+    }
+
+    public void summaryByPay(){
+        Customer[] customers = toArray();
+        String order = "";
+
+        while(true){
+            System.out.println("Which order (ASCENDING (A), DESCENDING (D))?");
+            try{
+                order = nextLine(Message.END_MSG);
+
+                if(order.equals("A"))
+                    Arrays.sort(customers, new Comparator<Customer>() {
+                        @Override
+                        public int compare(Customer o1, Customer o2) {
+                            return o1.getCusTotalPay().compareTo(o2.getCusTotalPay());
+                        }
+                    });
+                if(order.equals("D"))
+                    Arrays.sort(customers, new Comparator<Customer>() {
+                        @Override
+                        public int compare(Customer o1, Customer o2) {
+                            return o1.getCusTotalPay().compareTo(o2.getCusTotalPay()) * -1;
+                        }
+                    });
+
+                for(int i = 0; i < allGroups.size(); i++){
+                    Group group = allGroups.get(i);
+                    System.out.println("==============================");
+                    System.out.println("Group : " + group.getGroupType() +
+                            " ( Time : " + group.getParameter().getMinTime() + ", Pay : "
+                            + group.getParameter().getMinPay() + " )");
+                    System.out.println("==============================");
+
+                    for(int j = 0; j < customers.length; j++){
+                        if(allGroups.get(i).getGroupType().equals(customers[j].getGroup().getGroupType())){
+                            System.out.println("No. " + (j + 1) + " => " + customers[j]);
+                        }
+                    }
+                }
+            }catch (InputEndException e){
+                System.out.println(Message.ERR_MSG_INPUT_END);
+                break;
+            }
+        }
+
+
+    }
+    public Customer[] toArray(){
+        Customer[] customers = new Customer[allCustomers.size()];
+        for(int i = 0; i < allCustomers.size(); i++){
+            customers[i] = allCustomers.get(i);
+        }
+
+        return customers;
+    }
+
+}
diff --git a/me/smartstore/util/Message.java b/me/smartstore/util/Message.java
new file mode 100644
index 00000000..328958cc
--- /dev/null
+++ b/me/smartstore/util/Message.java
@@ -0,0 +1,14 @@
+package me.smartstore.util;
+
+public interface Message {
+    String ERR_MSG_INVALID_ARR_EMPTY = "No Customers. Please input one first.";
+    String ERR_MSG_NULL_ARR_ELEMENT = "Elements in Array has null. Array can't be sorted.";
+    String ERR_MSG_INVALID_INPUT_NULL = "Null Input. Please input something.";
+    String ERR_MSG_INVALID_INPUT_EMPTY = "Empty Input. Please input something.";
+    String ERR_MSG_INVALID_INPUT_RANGE = "Invalid Input. Please try again.";
+    String ERR_MSG_INVALID_INPUT_TYPE = "Invalid Type for Input. Please try again.";
+    String ERR_MSG_INVALID_INPUT_FORMAT = "Invalid Format for Input. Please try again.";
+    String ERR_MSG_INPUT_END = "END is pressed. Exit this menu.";
+    String ERR_MSG_INVALID_INDEX_BOUND = "Index Out of Bounds. Please try again.";
+    String END_MSG = "END";
+}