diff --git a/.idea/.gitignore b/.idea/.gitignore
new file mode 100644
index 00000000..26d33521
--- /dev/null
+++ b/.idea/.gitignore
@@ -0,0 +1,3 @@
+# Default ignored files
+/shelf/
+/workspace.xml
diff --git a/jyjang/smartstore/Main.java b/jyjang/smartstore/Main.java
new file mode 100644
index 00000000..b41e1ddd
--- /dev/null
+++ b/jyjang/smartstore/Main.java
@@ -0,0 +1,9 @@
+package jyjang.smartstore;
+
+public class Main {
+
+    public static void main(String[] args) {
+//        SmartStoreApplication.getInstance().test().run();
+        SmartStoreApplication.getInstance().run();
+    }
+}
diff --git a/jyjang/smartstore/SmartStoreApplication.java b/jyjang/smartstore/SmartStoreApplication.java
new file mode 100644
index 00000000..bd5316cb
--- /dev/null
+++ b/jyjang/smartstore/SmartStoreApplication.java
@@ -0,0 +1,45 @@
+package jyjang.smartstore;
+
+import jyjang.smartstore.customer.Customers;
+import jyjang.smartstore.group.Groups;
+import jyjang.smartstore.menu.*;
+
+public class SmartStoreApplication {
+
+    private static SmartStoreApplication smartStoreApplication;
+
+    public static SmartStoreApplication getInstance() {
+        if (smartStoreApplication == null)
+            smartStoreApplication = new SmartStoreApplication();
+        return smartStoreApplication;
+    }
+
+
+
+    private final Groups allGroups = Groups.getInstance();
+    private final Customers allCustomers = Customers.getInstance();
+
+    private final MainMenu mainMenu = MainMenu.getInstance();
+
+    public SmartStoreApplication test() {
+//        this.allGroups.add(new Group(GroupType.GENERAL, new Parameter(Integer.valueOf(10), Integer.valueOf(100000))));
+//        this.allGroups.add(new Group(GroupType.VIP, new Parameter(Integer.valueOf(20), Integer.valueOf(200000))));
+//        this.allGroups.add(new Group(GroupType.VVIP, new Parameter(Integer.valueOf(30), Integer.valueOf(300000))));
+//        for (int i = 0; i < 20; i++)
+//            this.allCustomers.add(new Customer(
+//                    Character.toString((char)(97 + i)), "" + (char)(97 + i) + "123", (
+//
+//                    (int)(Math.random() * 5.0D) + 1) * 10, (
+//                    (int)(Math.random() * 5.0D) + 1) * 100000));
+//        this.allCustomers.refresh(this.allGroups);
+        return this;
+    }
+
+    private SmartStoreApplication() {
+
+    }
+
+    public void run() {
+        mainMenu.manage();
+    }
+}
diff --git a/jyjang/smartstore/arrays/Collections.java b/jyjang/smartstore/arrays/Collections.java
new file mode 100644
index 00000000..ea219522
--- /dev/null
+++ b/jyjang/smartstore/arrays/Collections.java
@@ -0,0 +1,14 @@
+package jyjang.smartstore.arrays;
+
+public interface Collections<T> {
+
+    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);
+}
diff --git a/jyjang/smartstore/arrays/DArray.java b/jyjang/smartstore/arrays/DArray.java
new file mode 100644
index 00000000..0e813915
--- /dev/null
+++ b/jyjang/smartstore/arrays/DArray.java
@@ -0,0 +1,163 @@
+package jyjang.smartstore.arrays;
+
+import jyjang.smartstore.exception.ElementNotFoundException;
+import jyjang.smartstore.exception.EmptyArrayException;
+import jyjang.smartstore.exception.NullArgumentException;
+
+// Dynamic Array
+public class DArray<T> implements Collections<T> {
+
+    protected static final int DEFAULT = 10;
+
+    protected T[] arrays;
+    protected int size;
+    protected int capacity;
+
+    @SuppressWarnings("unchecked")
+    public DArray() {
+        arrays = (T[]) new Object[DEFAULT];
+        capacity = DEFAULT;
+    }
+
+    @SuppressWarnings("unchecked")
+    public DArray(int initial) {
+        arrays = (T[]) new Object[initial];
+        capacity = initial;
+    }
+
+    public DArray(T[] arrays) {
+        this.arrays = arrays;
+        capacity = arrays.length;
+        size = arrays.length;
+    }
+
+    @Override
+    public int size() {
+        return size;
+    }
+
+    // protected => 배열에 얼마나 capacity 남아있는지 외부에 알려줄 필요가 없기 때문
+    protected int capacity() {
+        return capacity;
+    }
+
+    @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;
+    }
+
+    @Override
+    public int indexOf(T object) throws NullArgumentException, ElementNotFoundException {
+        // not found (instead of throwing exception)
+        if (object == null) {
+            throw new NullArgumentException();
+        }
+
+        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 argument is null, do not add null value in array
+        if (object == null) {
+            throw new NullArgumentException();
+        }
+
+        if (size < capacity) {
+            arrays[size] = object;
+            size++;
+        } else {
+            grow();
+            add(object);
+        }
+    }
+
+    @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);
+        }
+    }
+
+    @Override
+    public T pop() {
+        return pop(size-1);
+    }
+
+    @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;
+    }
+
+    @Override
+    public T pop(T object) {
+        return pop(indexOf(object));
+    }
+
+    protected void grow() {
+        capacity *= 2; // doubling
+        arrays = java.util.Arrays.copyOf(arrays, capacity);
+    }
+
+    @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/jyjang/smartstore/customer/Customer.java b/jyjang/smartstore/customer/Customer.java
new file mode 100644
index 00000000..3cc9b31a
--- /dev/null
+++ b/jyjang/smartstore/customer/Customer.java
@@ -0,0 +1,94 @@
+package jyjang.smartstore.customer;
+
+import jyjang.smartstore.group.Group;
+
+import java.util.Objects;
+
+public class Customer {
+
+    private String cName;
+    private String cId;
+    private Integer totalTime;
+    private Integer totalPay;
+
+    private Group group;
+
+    public Customer() {
+
+    }
+
+    public Customer(String cName, String cId) {
+        this.cName = cName;
+        this.cId = cId;
+    }
+
+    public Customer(String cName, String cId, Integer totalTime, Integer totalPay) {
+        this.cName = cName;
+        this.cId = cId;
+        this.totalTime = totalTime;
+        this.totalPay = totalPay;
+    }
+
+    public String getcName() {
+        return cName;
+    }
+
+    public void setcName(String cName) {
+        this.cName = cName;
+    }
+
+    public String getcId() {
+        return cId;
+    }
+
+    public void setcId(String cId) {
+        this.cId = cId;
+    }
+
+    public Integer getTotalTime() {
+        return totalTime;
+    }
+
+    public void setTotalTime(Integer totalTime) {
+        this.totalTime = totalTime;
+    }
+
+    public Integer getTotalPay() {
+        return totalPay;
+    }
+
+    public void setTotalPay(Integer totalPay) {
+        this.totalPay = totalPay;
+    }
+
+    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(cId, customer.cId);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(cId);
+    }
+
+    @Override
+    public String toString() {
+        return "Customer{" +
+                "cName='" + cName + '\'' +
+                ", cId='" + cId + '\'' +
+                ", totalTime=" + totalTime +
+                ", totalPay=" + totalPay +
+                '}';
+    }
+}
diff --git a/jyjang/smartstore/customer/Customers.java b/jyjang/smartstore/customer/Customers.java
new file mode 100644
index 00000000..56165814
--- /dev/null
+++ b/jyjang/smartstore/customer/Customers.java
@@ -0,0 +1,52 @@
+package jyjang.smartstore.customer;
+
+import jyjang.smartstore.arrays.DArray;
+import jyjang.smartstore.group.Group;
+import jyjang.smartstore.group.GroupType;
+import jyjang.smartstore.group.Groups;
+
+public class Customers extends DArray<Customer> {
+
+    // singleton
+    private static Customers allCustomers;
+    private final Groups allGroups;
+
+    public static Customers getInstance() {
+        if (allCustomers == null) {
+            allCustomers = new Customers();
+        }
+        return allCustomers;
+    }
+
+    private Customers() {
+        this.allGroups = Groups.getInstance();
+    }
+
+    // refresh 함수가 호출되는 경우
+    // 1. 분류기준 바뀔 때
+    // 2. 새로운 고객이 들어올 때
+    public void refresh() {
+        for (int i = 0; i < allCustomers.size(); i++) {
+            Customer customer = allCustomers.get(i);
+            customer.setGroup(findGroupByCustomer(customer));
+        }
+
+    }
+
+    public Group findGroupByCustomer(Customer customer) {
+
+        int totalPay = customer.getTotalPay();
+        int totalTime = customer.getTotalTime();
+
+        for (int i = allGroups.size() - 1; i >= 0; i--) {
+            Group group = allGroups.get(i);
+
+            if (totalPay >= group.getParameter().getMinimumTotalPay() && totalTime >= group.getParameter().getMinimumSpentTime()) {
+                return group;
+            }
+        }
+
+        return null;
+    }
+
+}
diff --git a/jyjang/smartstore/exception/ElementNotFoundException.java b/jyjang/smartstore/exception/ElementNotFoundException.java
new file mode 100644
index 00000000..bae68f47
--- /dev/null
+++ b/jyjang/smartstore/exception/ElementNotFoundException.java
@@ -0,0 +1,22 @@
+package jyjang.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/jyjang/smartstore/exception/EmptyArrayException.java b/jyjang/smartstore/exception/EmptyArrayException.java
new file mode 100644
index 00000000..9a4f2a7c
--- /dev/null
+++ b/jyjang/smartstore/exception/EmptyArrayException.java
@@ -0,0 +1,22 @@
+package jyjang.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/jyjang/smartstore/exception/InputEndException.java b/jyjang/smartstore/exception/InputEndException.java
new file mode 100644
index 00000000..f4e130cf
--- /dev/null
+++ b/jyjang/smartstore/exception/InputEndException.java
@@ -0,0 +1,23 @@
+package jyjang.smartstore.exception;
+
+public class InputEndException extends RuntimeException {
+
+    public InputEndException() {
+    }
+
+    public InputEndException(String message) {
+        super(message);
+    }
+
+    public InputEndException(String message, Throwable cause) {
+        super(message, cause);
+    }
+
+    public InputEndException(Throwable cause) {
+        super(cause);
+    }
+
+    public InputEndException(String message, Throwable cause, boolean enableSuppression, boolean writableStackTrace) {
+        super(message, cause, enableSuppression, writableStackTrace);
+    }
+}
diff --git a/jyjang/smartstore/exception/InputRangeException.java b/jyjang/smartstore/exception/InputRangeException.java
new file mode 100644
index 00000000..98342b6b
--- /dev/null
+++ b/jyjang/smartstore/exception/InputRangeException.java
@@ -0,0 +1,24 @@
+package jyjang.smartstore.exception;
+
+public class InputRangeException extends RuntimeException {
+
+    public InputRangeException() {
+    }
+
+    public InputRangeException(String message) {
+        super(message);
+    }
+
+    public InputRangeException(String message, Throwable cause) {
+        super(message, cause);
+    }
+
+    public InputRangeException(Throwable cause) {
+        super(cause);
+    }
+
+    public InputRangeException(String message, Throwable cause, boolean enableSuppression, boolean writableStackTrace) {
+        super(message, cause, enableSuppression, writableStackTrace);
+    }
+
+}
diff --git a/jyjang/smartstore/exception/NullArgumentException.java b/jyjang/smartstore/exception/NullArgumentException.java
new file mode 100644
index 00000000..24530a2e
--- /dev/null
+++ b/jyjang/smartstore/exception/NullArgumentException.java
@@ -0,0 +1,22 @@
+package jyjang.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);
+    }
+}
diff --git a/jyjang/smartstore/group/Group.java b/jyjang/smartstore/group/Group.java
new file mode 100644
index 00000000..96196579
--- /dev/null
+++ b/jyjang/smartstore/group/Group.java
@@ -0,0 +1,54 @@
+package jyjang.smartstore.group;
+
+import java.util.Objects;
+
+public class Group {
+
+    private Parameter parameter; // 분류기준
+    private GroupType groupType; // 그룹 타입
+
+    public Group() {
+    }
+
+    public Group(GroupType groupType, Parameter parameter) {
+        this.groupType = groupType;
+        this.parameter = parameter;
+    }
+
+    public GroupType getGroupType() {
+        return groupType;
+    }
+
+    public void setGroupType(GroupType groupType) {
+        this.groupType = groupType;
+    }
+
+    public Parameter getParameter() {
+        return parameter;
+    }
+
+    public void setParameter(Parameter parameter) {
+        this.parameter = parameter;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        Group group = (Group) o;
+        return groupType == group.groupType && Objects.equals(parameter, group.parameter);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(groupType, parameter);
+    }
+
+    @Override
+    public String toString() {
+        return "Group{" +
+                "groupType=" + groupType +
+                ", parameter=" + parameter +
+                '}';
+    }
+}
diff --git a/jyjang/smartstore/group/GroupType.java b/jyjang/smartstore/group/GroupType.java
new file mode 100644
index 00000000..f0cee830
--- /dev/null
+++ b/jyjang/smartstore/group/GroupType.java
@@ -0,0 +1,41 @@
+package jyjang.smartstore.group;
+
+import java.util.Arrays;
+
+public enum GroupType {
+    NONE("N", "해당없음")
+    , GENERAL("G", "일반고객")
+    , VIP("V", "우수고객")
+    , VVIP("VV", "최우수고객");
+
+
+    String label;
+    final String groupType;
+
+    GroupType(String initial, String groupType) {
+        this.label = initial;
+        this.groupType = groupType;
+    }
+
+    public String getLabel() {
+        return label;
+    }
+
+    public String getGroupType() {
+        return groupType;
+    }
+
+    public static GroupType getGroupTypeByInitial(String label) {
+        GroupType groupType = Arrays.stream(values())
+                .filter(type -> type.label.equals(label.toUpperCase()))
+                .findAny()
+                .orElse(null);
+
+        if(null == groupType) {
+            throw new IllegalArgumentException();
+        }
+
+        return groupType;
+    }
+
+}
\ No newline at end of file
diff --git a/jyjang/smartstore/group/Groups.java b/jyjang/smartstore/group/Groups.java
new file mode 100644
index 00000000..c257f243
--- /dev/null
+++ b/jyjang/smartstore/group/Groups.java
@@ -0,0 +1,35 @@
+package jyjang.smartstore.group;
+
+import jyjang.smartstore.arrays.DArray;
+import jyjang.smartstore.customer.Customer;
+import jyjang.smartstore.customer.Customers;
+
+import java.util.Collections;
+
+public class Groups extends DArray<Group> {
+
+    private static Groups allGroups;
+
+    public static Groups getInstance() {
+        if (allGroups == null)
+            allGroups = new Groups();
+        return allGroups;
+    }
+
+    private Groups() {
+
+    }
+
+    private Group[] groups;
+
+    public Group find(GroupType groupType) {
+        for (int i = 0; i < allGroups.size; i++) {
+            if (allGroups.get(i).getGroupType() == groupType) {
+                return allGroups.get(i);
+            }
+        }
+        return null;
+
+    }
+
+}
diff --git a/jyjang/smartstore/group/Parameter.java b/jyjang/smartstore/group/Parameter.java
new file mode 100644
index 00000000..1d86fda2
--- /dev/null
+++ b/jyjang/smartstore/group/Parameter.java
@@ -0,0 +1,47 @@
+package jyjang.smartstore.group;
+
+import java.util.Objects;
+
+public class Parameter {
+
+    private Integer minimumSpentTime;
+    private Integer minimumTotalPay;
+
+    public Parameter() {
+
+    }
+
+    public Parameter(Integer minimumSpentTime, Integer minimumTotalPay) {
+        this.minimumSpentTime = minimumSpentTime;
+        this.minimumTotalPay = minimumTotalPay;
+    }
+
+    public Integer getMinimumSpentTime() {
+        return minimumSpentTime;
+    }
+
+    public void setMinimumSpentTime(Integer minimumSpentTime) {
+        this.minimumSpentTime = minimumSpentTime;
+    }
+
+    public Integer getMinimumTotalPay() {
+        return minimumTotalPay;
+    }
+
+    public void setMinimumTotalPay(Integer minimumTotalPay) {
+        this.minimumTotalPay = minimumTotalPay;
+    }
+
+    @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(minimumSpentTime, parameter.minimumSpentTime) && Objects.equals(minimumTotalPay, parameter.minimumTotalPay);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(minimumSpentTime, minimumTotalPay);
+    }
+}
diff --git a/jyjang/smartstore/menu/CustomerMenu.java b/jyjang/smartstore/menu/CustomerMenu.java
new file mode 100644
index 00000000..03ad6a4b
--- /dev/null
+++ b/jyjang/smartstore/menu/CustomerMenu.java
@@ -0,0 +1,30 @@
+package jyjang.smartstore.menu;
+
+public class CustomerMenu implements Menu {
+
+    private static CustomerMenu customerMenu;
+
+    public static CustomerMenu getInstance() {
+        if (customerMenu == null)
+            customerMenu = new CustomerMenu();
+        return customerMenu;
+    }
+
+    private CustomerMenu() {
+        super();
+
+    }
+
+    @Override
+    public void manage() {
+        while (true) {
+            int choice = displayMenu(new String[] {
+                    "Add Customer"
+                    , "View Customer"
+                    , "Update Customer"
+                    , "Delete Customer"
+                    , "Back"});
+        }
+
+    }
+}
diff --git a/jyjang/smartstore/menu/GroupMenu.java b/jyjang/smartstore/menu/GroupMenu.java
new file mode 100644
index 00000000..462ceb52
--- /dev/null
+++ b/jyjang/smartstore/menu/GroupMenu.java
@@ -0,0 +1,164 @@
+package jyjang.smartstore.menu;
+
+import jyjang.smartstore.customer.Customers;
+import jyjang.smartstore.exception.InputEndException;
+import jyjang.smartstore.exception.InputRangeException;
+import jyjang.smartstore.group.Group;
+import jyjang.smartstore.group.GroupType;
+import jyjang.smartstore.group.Groups;
+import jyjang.smartstore.group.Parameter;
+import jyjang.smartstore.util.Message;
+
+public class GroupMenu implements Menu {
+
+    private final Groups allGroups = Groups.getInstance();
+    private final Customers allCustomers = Customers.getInstance();
+
+    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 = displayMenu(new String[] {
+                    "Set Parameter"
+                    , "View Parameter"
+                    , "Update Parameter"
+                    , "Back"});
+
+            if (choice == 1) {
+                setParameter();
+            } else if (choice == 2) {
+                viewParameter();
+            } else if (choice == 3) {
+                updateParameter();
+            } else if (choice == 4) {
+                break;
+            }
+        }
+    }
+
+    public GroupType chooseGroup() {
+        while (true) {
+            try {
+                System.out.println("Which group (GENERAL (G),  VIP (V), VVIP (VV))? ");
+                // 프로그램을 끝내기 위한 신호기 때문에 내부 메소드에 입력 23.04.27
+                String choice = nextLine(Message.END_MSG);
+
+                GroupType groupType = GroupType.getGroupTypeByInitial(choice);
+                return groupType;
+            } catch (InputEndException e) {
+                System.out.println(Message.ERR_MSG_INPUT_END);
+                return null;
+            } catch (IllegalArgumentException e) {
+                System.out.println(Message.ERR_MSG_INVALID_INPUT_RANGE);
+            }
+        }
+    }
+
+    private void setParameter() {
+        while (true) {
+            GroupType groupType = chooseGroup();
+
+            Group group = allGroups.find(groupType);
+
+            if (group != null && group.getParameter() != null) {
+                System.out.println("\n" + group.getGroupType() + " group already exists.");
+                System.out.println("\n" + group);
+            } else {
+                Parameter parameter = new Parameter();
+
+                while (true) {
+                    int choice = displayMenu(new String[] {
+                            "Minimum Spent Time"
+                            , "Minimum Total Pay"
+                            , "Back" });
+                    if (choice == 1) {
+                        setParameterMinimumSpentTime(parameter);
+                        continue;
+                    }
+                    if (choice == 2) {
+                        setParameterMinimumTotalPay(parameter);
+                        continue;
+                    }
+                    if (choice == 3)
+                        break;
+                }
+
+                allGroups.add(new Group(groupType, parameter));
+                allCustomers.refresh();
+            }
+        }
+    }
+
+    private void viewParameter() {
+    }
+
+    private void updateParameter() {
+    }
+
+    private void setParameterMinimumSpentTime(Parameter parameter) {
+        while (true) {
+            try {
+                System.out.println();
+                System.out.println("Input Minimum Spent Time : ");
+
+                int minimumSpentTime = Integer.parseInt(nextLine("end"));
+                if (minimumSpentTime < 0) {
+                    throw new InputRangeException();
+                }
+
+                parameter.setMinimumSpentTime(minimumSpentTime);
+                return;
+            } catch (InputRangeException e) {
+                System.out.println();
+                System.out.println(Message.ERR_MSG_INVALID_INPUT_RANGE);
+            } catch (NumberFormatException e) {
+                System.out.println();
+                System.out.println(Message.ERR_MSG_INVALID_INPUT_TYPE);
+            } catch (InputEndException e) {
+                System.out.println();
+                System.out.println(Message.ERR_MSG_INPUT_END);
+                break;
+            }
+        }
+    }
+
+    private void setParameterMinimumTotalPay(Parameter parameter) {
+        while (true) {
+            try {
+                System.out.println();
+                System.out.println("Input Minimum Spent Time : ");
+
+                int minimumTotalPay = Integer.parseInt(nextLine("end"));
+                if (minimumTotalPay < 0) {
+                    throw new InputRangeException();
+                }
+
+                parameter.setMinimumTotalPay(minimumTotalPay);
+                return;
+            } catch (InputRangeException e) {
+                System.out.println();
+                System.out.println(Message.ERR_MSG_INVALID_INPUT_RANGE);
+            } catch (NumberFormatException e) {
+                System.out.println();
+                System.out.println(Message.ERR_MSG_INVALID_INPUT_TYPE);
+            } catch (InputEndException e) {
+                System.out.println();
+                System.out.println(Message.ERR_MSG_INPUT_END);
+                break;
+            }
+        }
+    }
+
+}
+
diff --git a/jyjang/smartstore/menu/MainMenu.java b/jyjang/smartstore/menu/MainMenu.java
new file mode 100644
index 00000000..a12ae3a0
--- /dev/null
+++ b/jyjang/smartstore/menu/MainMenu.java
@@ -0,0 +1,44 @@
+package jyjang.smartstore.menu;
+
+public class MainMenu implements Menu {
+
+    private static MainMenu mainMenu;
+
+    public static MainMenu getInstance() {
+        if (mainMenu == null)
+            mainMenu = new MainMenu();
+        return mainMenu;
+    }
+
+    private MainMenu() {
+
+    }
+
+    private final CustomerMenu customerMenu = CustomerMenu.getInstance();
+    private final GroupMenu groupMenu = GroupMenu.getInstance();
+    private final SummarizedMenu summarizedMenu = SummarizedMenu.getInstance();
+
+
+    @Override
+    public void manage() {
+        // 프로그램을 실행(유지) While
+        while (true) {
+            int choice = mainMenu.displayMenu(new String[] {
+                    "Parameter"
+                    , "Customer Data"
+                    , "Classification Summary"
+                    , "Quit"});
+
+            if (choice == 1) {
+                groupMenu.manage();
+            } else if (choice == 2) {
+                customerMenu.manage();
+            } else if (choice == 3) {
+                summarizedMenu.manage();
+            } else if (choice == 4) {
+                System.out.println("Program Finished");
+                break;
+            }
+        }
+    }
+}
diff --git a/jyjang/smartstore/menu/Menu.java b/jyjang/smartstore/menu/Menu.java
new file mode 100644
index 00000000..0a510ad7
--- /dev/null
+++ b/jyjang/smartstore/menu/Menu.java
@@ -0,0 +1,61 @@
+package jyjang.smartstore.menu;
+
+import jyjang.smartstore.exception.InputEndException;
+import jyjang.smartstore.exception.InputRangeException;
+import jyjang.smartstore.util.Message;
+
+import java.util.Scanner;
+
+public interface Menu {
+
+    Scanner scanner = new Scanner(System.in);
+
+    // 필요 없으면 사용하지 않아도 괜찮다고 하심
+    default String nextLine() {
+        return scanner.nextLine().toUpperCase();
+    }
+
+    default String nextLine(String end) throws InputEndException {
+        System.out.println("** Press 'end', if you want to exit! **");
+        String inputString = scanner.nextLine().toUpperCase();
+        if (inputString.equals(end)) {
+            throw new InputEndException();
+        }
+
+        return inputString;
+    }
+
+
+    // 예외 복구 While
+    default int displayMenu(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();
+
+            } catch (NumberFormatException e) {
+                System.out.println(Message.ERR_MSG_INVALID_INPUT_FORMAT);
+
+            } catch (InputRangeException e) {
+                System.out.println(Message.ERR_MSG_INVALID_INPUT_RANGE);
+
+            }
+        }
+    }
+
+    // 각 서브메뉴를 관리하는 함수(서브 메뉴의 최상위 함수)
+    void manage();
+}
diff --git a/jyjang/smartstore/menu/SummarizedMenu.java b/jyjang/smartstore/menu/SummarizedMenu.java
new file mode 100644
index 00000000..d5a911e2
--- /dev/null
+++ b/jyjang/smartstore/menu/SummarizedMenu.java
@@ -0,0 +1,28 @@
+package jyjang.smartstore.menu;
+
+public class SummarizedMenu implements Menu {
+
+    private static SummarizedMenu summarizedMenu;
+
+    public static SummarizedMenu getInstance() {
+        if (summarizedMenu == null)
+            summarizedMenu = new SummarizedMenu();
+        return summarizedMenu;
+    }
+
+    private SummarizedMenu() {
+
+    }
+
+    @Override
+    public void manage() {
+        while (true) {
+            int choice = displayMenu(new String[] {
+                    "Summary"
+                    , "Summary (Sorted By Name)"
+                    , "Summary (Sorted By Time)"
+                    , "Summary (Sorted By Pay)"
+                    , "Back"});
+        }
+    }
+}
diff --git a/jyjang/smartstore/util/Message.java b/jyjang/smartstore/util/Message.java
new file mode 100644
index 00000000..eb67638b
--- /dev/null
+++ b/jyjang/smartstore/util/Message.java
@@ -0,0 +1,13 @@
+package jyjang.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 END_MSG = "END";
+}
\ No newline at end of file