To create a simple ATM machine simulation in C#, you'll need to follow these steps:

1. Install SQLite package
2. Create an Account class
3. Set up the database connection and table creation
4. Implement account creation, deposit, withdrawal, and balance checking methods
5. Add user input validation and error handling

Here's a sample implementation of this application:

1. First, install the `System.Data.SQLite` NuGet package by running the following command in your project directory:

```
dotnet add package System.Data.SQLite
```

2. Create an `Account` class with properties for the account number, name, and balance:

```csharp
public class Account
{
    public int AccountNumber { get; set; }
    public string Name { get; set; }
    public decimal Balance { get; set; }
}
```

3. Set up the database connection and table creation:

```csharp
using System;
using System.Data;
using System.Data.SQLite;

namespace SimpleATM
{
    public static class Database
    {
        private const string ConnectionString = "Data Source=accounts.db";

        public static void Initialize()
        {
            using var connection = new SQLiteConnection(ConnectionString);
            connection.Open();

            using var command = new SQLiteCommand(connection);
            command.CommandText = @"CREATE TABLE IF NOT EXISTS accounts (
                                        account_number INTEGER PRIMARY KEY,
                                        name TEXT NOT NULL,
                                        balance REAL NOT NULL)";
            command.ExecuteNonQuery();
        }
    }
}
```

4. Implement account creation, deposit, withdrawal, and balance checking methods:

```csharp
using System;
using System.Data;
using System.Data.SQLite;

namespace SimpleATM
{
    public static class AccountManager
    {
        private const string ConnectionString = "Data Source=accounts.db";

        public static Account CreateAccount(string name)
        {
            using var connection = new SQLiteConnection(ConnectionString);
            connection.Open();

            using var command = new SQLiteCommand(connection);
            command.CommandText = "INSERT INTO accounts (name, balance) VALUES (@name, 0)";
            command.Parameters.AddWithValue("@name", name);
            command.ExecuteNonQuery();

            return GetAccountByName(name);
        }

        public static Account GetAccount(int accountNumber)
        {
            using var connection = new SQLiteConnection(ConnectionString);
            connection.Open();

            using var command = new SQLiteCommand(connection);
            command.CommandText = "SELECT * FROM accounts WHERE account_number = @accountNumber";
            command.Parameters.AddWithValue("@accountNumber", accountNumber);

            using var reader = command.ExecuteReader();
            if (!reader.Read())
            {
                return null;
            }

            return new Account
            {
                AccountNumber = reader.GetInt32(0),
                Name = reader.GetString(1),
                Balance = reader.GetDecimal(2)
            };
        }

        public static Account GetAccountByName(string name)
        {
            using var connection = new SQLiteConnection(ConnectionString);
            connection.Open();

            using var command = new SQLiteCommand(connection);
            command.CommandText = "SELECT * FROM accounts WHERE name = @name";
            command.Parameters.AddWithValue("@name", name);

            using var reader = command.ExecuteReader();
            if (!reader.Read())
            {
                return null;
            }

            return new Account
            {
                AccountNumber = reader.GetInt32(0),
                Name = reader.GetString(1),
                Balance = reader.GetDecimal(2)
            };
        }

        public static void Deposit(Account account, decimal amount)
        {
            using var connection = new SQLiteConnection(ConnectionString);
            connection.Open();

            using var command = new SQLiteCommand(connection);
            command.CommandText = @"UPDATE accounts 
                                    SET balance = balance + @amount 
                                    WHERE account_number = @accountNumber";
            command.Parameters.AddWithValue("@amount", amount);
            command.Parameters.AddWithValue("@accountNumber", account.AccountNumber);
            command.ExecuteNonQuery();
        }

        public static bool Withdraw(Account account, decimal amount)
        {
            if (account.Balance < amount)
            {
                return false;
            }

            using var connection = new SQLiteConnection(ConnectionString);
            connection.Open();

            using var command = new SQLiteCommand(connection);
            command.CommandText = @"UPDATE accounts 
                                    SET balance = balance - @amount 
                                    WHERE account_number = @accountNumber";
            command.Parameters.AddWithValue("@amount", amount);
            command.Parameters.AddWithValue("@accountNumber", account.AccountNumber);
            command.ExecuteNonQuery();

            return true;
        }
    }
}
```

5. Add user input validation and error handling:

```csharp
using System;

namespace SimpleATM
{
    class Program
    {
        static void Main(string[] args)
        {
            Database.Initialize();

            Console.WriteLine("Welcome to the Simple ATM!");
            Console.Write("Enter your name: ");
            string name = Console.ReadLine();

            Account account = AccountManager.GetAccountByName(name) ?? AccountManager.CreateAccount(name);

            while (true)
            {
                Console.WriteLine("\nChoose an option:");
                Console.WriteLine("1. Check balance");
                Console.WriteLine("2. Deposit");
                Console.WriteLine("3. Withdraw");
                Console.WriteLine("4. Exit");

                int choice = int.Parse(Console.ReadLine());

                switch (choice)
                {
                    case 1:
                        account = AccountManager.GetAccount(account.AccountNumber);
                        Console.WriteLine($"Your current balance is: {account.Balance:C}");
                        break;
                    case 2:
                        Console.Write("Enter deposit amount: ");
                        decimal depositAmount = decimal.Parse(Console.ReadLine());
                        AccountManager.Deposit(account, depositAmount);
                        Console.WriteLine($"Deposited {depositAmount:C} successfully.");
                        break;
                    case 3:
                        Console.Write("Enter withdrawal amount: ");
                        decimal withdrawalAmount = decimal.Parse(Console.ReadLine());
                        if (AccountManager.Withdraw(account, withdrawalAmount))
                        {
                            Console.WriteLine($"Withdrew {withdrawalAmount:C} successfully.");
                        }
                        else
                        {
                            Console.WriteLine("Insufficient balance for withdrawal.");
                        }
                        break;
                    case 4:
                        Console.WriteLine("Goodbye!");
                        return;
                }
            }
        }
    }
}
```

This implementation provides a simple console application that simulates an ATM machine. Users can create accounts, deposit and withdraw money, and check their account balance. Account information is stored in a local SQLite database, and proper validation and error handling are implemented for user inputs.
C#에서 간단한 ATM 기기 시뮬레이션을 만들려면 다음 단계를 따라야 합니다.

1. SQLite 패키지를 설치합니다
2. 계정 클래스 생성
3. 데이터베이스 연결 및 테이블 생성 설정
4. 계정 생성, 입금, 출금 및 잔액 확인 메서드 구현
5. 사용자 입력 유효성 검사 및 오류 처리 추가

이 애플리케이션의 샘플 구현은 다음과 같습니다.

1. 먼저 프로젝트 디렉터리에서 다음 명령을 실행하여 `System.Data.SQLite` NuGet 패키지를 설치합니다:

```
dotnet add package System.Data.SQLite
```

2. 계좌 번호, 이름, 잔액에 대한 속성이 있는 '계정' 클래스를 생성합니다:

```csharp
public class Account
{
    public int AccountNumber { get; set; }
    public string Name { get; set; }
    public decimal Balance { get; set; }
}
```

3. 데이터베이스 연결 및 테이블 생성을 설정합니다:

```csharp
using System;
using System.Data;
using System.Data.SQLite;

namespace SimpleATM
{
    public static class Database
    {
        private const string ConnectionString = "Data Source=accounts.db";

        public static void Initialize()
        {
            using var connection = new SQLiteConnection(ConnectionString);
            connection.Open();

            using var command = new SQLiteCommand(connection);
            command.CommandText = @"CREATE TABLE IF NOT EXISTS accounts (
                                        account_number INTEGER PRIMARY KEY,
                                        name TEXT NOT NULL,
                                        balance REAL NOT NULL)";
            command.ExecuteNonQuery();
        }
    }
}
```

4. 계좌 생성, 입금, 출금, 잔액 확인 방법을 구현합니다:

```csharp
using System;
using System.Data;
using System.Data.SQLite;

namespace SimpleATM
{
    public static class AccountManager
    {
        private const string ConnectionString = "Data Source=accounts.db";

        public static Account CreateAccount(string name)
        {
            using var connection = new SQLiteConnection(ConnectionString);
            connection.Open();

            using var command = new SQLiteCommand(connection);
            command.CommandText = "INSERT INTO accounts (name, balance) VALUES (@name, 0)";
            command.Parameters.AddWithValue("@name", name);
            command.ExecuteNonQuery();

            return GetAccountByName(name);
        }

        public static Account GetAccount(int accountNumber)
        {
            using var connection = new SQLiteConnection(ConnectionString);
            connection.Open();

            using var command = new SQLiteCommand(connection);
            command.CommandText = "SELECT * FROM accounts WHERE account_number = @accountNumber";
            command.Parameters.AddWithValue("@accountNumber", accountNumber);

            using var reader = command.ExecuteReader();
            if (!reader.Read())
            {
                return null;
            }

            return new Account
            {
                AccountNumber = reader.GetInt32(0),
                Name = reader.GetString(1),
                Balance = reader.GetDecimal(2)
            };
        }

        public static Account GetAccountByName(string name)
        {
            using var connection = new SQLiteConnection(ConnectionString);
            connection.Open();

            using var command = new SQLiteCommand(connection);
            command.CommandText = "SELECT * FROM accounts WHERE name = @name";
            command.Parameters.AddWithValue("@name", name);

            using var reader = command.ExecuteReader();
            if (!reader.Read())
            {
                return null;
            }

            return new Account
            {
                AccountNumber = reader.GetInt32(0),
                Name = reader.GetString(1),
                Balance = reader.GetDecimal(2)
            };
        }

        public static void Deposit(Account account, decimal amount)
        {
            using var connection = new SQLiteConnection(ConnectionString);
            connection.Open();

            using var command = new SQLiteCommand(connection);
            command.CommandText = @"UPDATE accounts 
                                    SET balance = balance + @amount 
                                    WHERE account_number = @accountNumber";
            command.Parameters.AddWithValue("@amount", amount);
            command.Parameters.AddWithValue("@accountNumber", account.AccountNumber);
            command.ExecuteNonQuery();
        }

        public static bool Withdraw(Account account, decimal amount)
        {
            if (account.Balance < amount)
            {
                return false;
            }

            using var connection = new SQLiteConnection(ConnectionString);
            connection.Open();

            using var command = new SQLiteCommand(connection);
            command.CommandText = @"UPDATE accounts 
                                    SET balance = balance - @amount 
                                    WHERE account_number = @accountNumber";
            command.Parameters.AddWithValue("@amount", amount);
            command.Parameters.AddWithValue("@accountNumber", account.AccountNumber);
            command.ExecuteNonQuery();

            return true;
        }
    }
}
```

5. 사용자 입력 유효성 검사 및 오류 처리를 추가합니다:

```csharp
using System;

namespace SimpleATM
{
    class Program
    {
        static void Main(string[] args)
        {
            Database.Initialize();

            Console.WriteLine("Welcome to the Simple ATM!");
            Console.Write("Enter your name: ");
            string name = Console.ReadLine();

            Account account = AccountManager.GetAccountByName(name) ?? AccountManager.CreateAccount(name);

            while (true)
            {
                Console.WriteLine("\nChoose an option:");
                Console.WriteLine("1. Check balance");
                Console.WriteLine("2. Deposit");
                Console.WriteLine("3. Withdraw");
                Console.WriteLine("4. Exit");

                int choice = int.Parse(Console.ReadLine());

                switch (choice)
                {
                    case 1:
                        account = AccountManager.GetAccount(account.AccountNumber);
                        Console.WriteLine($"Your current balance is: {account.Balance:C}");
                        break;
                    case 2:
                        Console.Write("Enter deposit amount: ");
                        decimal depositAmount = decimal.Parse(Console.ReadLine());
                        AccountManager.Deposit(account, depositAmount);
                        Console.WriteLine($"Deposited {depositAmount:C} successfully.");
                        break;
                    case 3:
                        Console.Write("Enter withdrawal amount: ");
                        decimal withdrawalAmount = decimal.Parse(Console.ReadLine());
                        if (AccountManager.Withdraw(account, withdrawalAmount))
                        {
                            Console.WriteLine($"Withdrew {withdrawalAmount:C} successfully.");
                        }
                        else
                        {
                            Console.WriteLine("Insufficient balance for withdrawal.");
                        }
                        break;
                    case 4:
                        Console.WriteLine("Goodbye!");
                        return;
                }
            }
        }
    }
}
```

이 구현은 ATM 기계를 시뮬레이션하는 간단한 콘솔 애플리케이션을 제공합니다. 사용자는 계좌를 만들고, 돈을 입출금하고, 계좌 잔액을 확인할 수 있습니다. 계정 정보는 로컬 SQLite 데이터베이스에 저장되며, 사용자 입력에 대한 적절한 유효성 검사 및 오류 처리가 구현됩니다.