To create a PHP web application that allows users to create, read, update, and delete (CRUD) notes stored in a MySQL database with user authentication and access control implemented, follow these steps:

1. Set up the development environment:
   - Install XAMPP or any other local server that supports PHP and MySQL.
   - Create a new folder for your project in the "htdocs" directory of your local server.

2. Create a MySQL database and tables:
   - Open phpMyAdmin from your local server dashboard and create a new database named "notes_app".
   - In this database, create two tables: "users" and "notes".

3. Design the table structure as follows:

   Users table:
   - id (INT, PRIMARY KEY, AUTO_INCREMENT)
   - username (VARCHAR)
   - email (VARCHAR)
   - password (VARCHAR)

   Notes table:
   - id (INT, PRIMARY KEY, AUTO_INCREMENT)
   - user_id (INT, FOREIGN KEY REFERENCES users(id))
   - title (VARCHAR)
   - content (TEXT)
   - created_at (DATETIME)
   - updated_at (DATETIME)

4. Create a configuration file (config.php) to store database connection details:

```php
<?php
$servername = "localhost";
$username = "root";
$password = "";
$dbname = "notes_app";

// Create connection
$conn = new mysqli($servername, $username, $password, $dbname);

// Check connection
if ($conn->connect_error) {
    die("Connection failed: " . $conn->connect_error);
}
?>
```

5. Create a registration form (register.php) for users to sign up:

```html
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Register</title>
</head>
<body>
    <h1>Register</h1>
    <form action="register_action.php" method="post">
        <label for="username">Username:</label>
        <input type="text" name="username" id="username" required><br>

        <label for="email">Email:</label>
        <input type="email" name="email" id="email" required><br>

        <label for="password">Password:</label>
        <input type="password" name="password" id="password" required><br>

        <button type="submit">Register</button>
    </form>
</body>
</html>
```

6. Create a PHP script (register_action.php) to handle user registration:

```php
<?php
require_once 'config.php';

$username = $_POST['username'];
$email = $_POST['email'];
$password = password_hash($_POST['password'], PASSWORD_DEFAULT);

$sql = "INSERT INTO users (username, email, password) VALUES (?, ?, ?)";
$stmt = $conn->prepare($sql);
$stmt->bind_param("sss", $username, $email, $password);

if ($stmt->execute()) {
    header("Location: login.php");
} else {
    echo "Error: " . $sql . "<br>" . $conn->error;
}

$stmt->close();
$conn->close();
?>
```

7. Create a login form (login.php) for users to sign in:

```html
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Login</title>
</head>
<body>
    <h1>Login</h1>
    <form action="login_action.php" method="post">
        <label for="email">Email:</label>
        <input type="email" name="email" id="email" required><br>

        <label for="password">Password:</label>
        <input type="password" name="password" id="password" required><br>

        <button type="submit">Login</button>
    </form>
</body>
</html>
```

8. Create a PHP script (login_action.php) to handle user authentication:

```php
<?php
session_start();
require_once 'config.php';

$email = $_POST['email'];
$password = $_POST['password'];

$sql = "SELECT * FROM users WHERE email = ?";
$stmt = $conn->prepare($sql);
$stmt->bind_param("s", $email);
$stmt->execute();
$result = $stmt->get_result();

if ($result->num_rows > 0) {
    $user = $result->fetch_assoc();
    if (password_verify($password, $user['password'])) {
        $_SESSION['user_id'] = $user['id'];
        header("Location: notes.php");
    } else {
        echo "Invalid password";
    }
} else {
    echo "User not found";
}

$stmt->close();
$conn->close();
?>
```

9. Create the main page (notes.php) to display and manage notes:

```html
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Notes</title>
</head>
<body>
    <h1>Your Notes</h1>
    <!-- Add your code here to display and manage notes -->
</body>
</html>
```

10. Implement CRUD operations for notes in the notes.php file.

11. To implement access control, add the following code at the beginning of each PHP file that requires user authentication:

```php
<?php
session_start();
if (!isset($_SESSION['user_id'])) {
    header("Location: login.php");
}
?>
```

This will redirect users to the login page if they are not logged in.

With these steps, you should have a basic PHP web application with CRUD functionality for notes and user authentication. You can further enhance the application by adding features like pagination, search, and sorting.
사용자 인증과 액세스 제어가 구현되어 사용자가 MySQL 데이터베이스에 저장된 노트를 만들고, 읽고, 업데이트하고, 삭제(CRUD)할 수 있는 PHP 웹 애플리케이션을 만들려면 다음 단계를 따르세요.

1. 개발 환경 설정
 - XAMPP 또는 PHP와 MySQL을 지원하는 다른 로컬 서버를 설치합니다.
 - 로컬 서버의 "htdocs" 디렉터리에 프로젝트용 새 폴더를 만듭니다.

2. MySQL 데이터베이스 및 테이블 만들기:
 - 로컬 서버 대시보드에서 phpMyAdmin을 열고 "notes_app"라는 이름의 새 데이터베이스를 만듭니다.
 - 이 데이터베이스에 두 개의 테이블을 만듭니다: "users" 및 "notes".

3. 테이블 구조를 다음과 같이 디자인합니다:

   Users table:
   - id (INT, PRIMARY KEY, AUTO_INCREMENT)
   - username (VARCHAR)
   - email (VARCHAR)
   - password (VARCHAR)

   Notes table:
   - id (INT, PRIMARY KEY, AUTO_INCREMENT)
   - user_id (INT, FOREIGN KEY REFERENCES users(id))
   - title (VARCHAR)
   - content (TEXT)
   - created_at (DATETIME)
   - updated_at (DATETIME)

4. 데이터베이스 연결 세부 정보를 저장할 구성 파일(config.php)을 생성합니다:

```php
<?php
$servername = "localhost";
$username = "root";
$password = "";
$dbname = "notes_app";

// Create connection
$conn = new mysqli($servername, $username, $password, $dbname);

// Check connection
if ($conn->connect_error) {
    die("Connection failed: " . $conn->connect_error);
}
?>
```

5. 사용자가 가입할 수 있는 등록 양식(register.php)을 만듭니다:

```html
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Register</title>
</head>
<body>
    <h1>Register</h1>
    <form action="register_action.php" method="post">
        <label for="username">Username:</label>
        <input type="text" name="username" id="username" required><br>

        <label for="email">Email:</label>
        <input type="email" name="email" id="email" required><br>

        <label for="password">Password:</label>
        <input type="password" name="password" id="password" required><br>

        <button type="submit">Register</button>
    </form>
</body>
</html>
```

6. 사용자 등록을 처리할 PHP 스크립트(register_action.php)를 생성합니다:

```php
<?php
require_once 'config.php';

$username = $_POST['username'];
$email = $_POST['email'];
$password = password_hash($_POST['password'], PASSWORD_DEFAULT);

$sql = "INSERT INTO users (username, email, password) VALUES (?, ?, ?)";
$stmt = $conn->prepare($sql);
$stmt->bind_param("sss", $username, $email, $password);

if ($stmt->execute()) {
    header("Location: login.php");
} else {
    echo "Error: " . $sql . "<br>" . $conn->error;
}

$stmt->close();
$conn->close();
?>
```

7. 사용자가 로그인할 수 있는 로그인 양식(login.php)을 생성합니다:

```html
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Login</title>
</head>
<body>
    <h1>Login</h1>
    <form action="login_action.php" method="post">
        <label for="email">Email:</label>
        <input type="email" name="email" id="email" required><br>

        <label for="password">Password:</label>
        <input type="password" name="password" id="password" required><br>

        <button type="submit">Login</button>
    </form>
</body>
</html>
```

8. 사용자 인증을 처리하는 PHP 스크립트(login_action.php)를 생성합니다:

```php
<?php
session_start();
require_once 'config.php';

$email = $_POST['email'];
$password = $_POST['password'];

$sql = "SELECT * FROM users WHERE email = ?";
$stmt = $conn->prepare($sql);
$stmt->bind_param("s", $email);
$stmt->execute();
$result = $stmt->get_result();

if ($result->num_rows > 0) {
    $user = $result->fetch_assoc();
    if (password_verify($password, $user['password'])) {
        $_SESSION['user_id'] = $user['id'];
        header("Location: notes.php");
    } else {
        echo "Invalid password";
    }
} else {
    echo "User not found";
}

$stmt->close();
$conn->close();
?>
```

9. 노트를 표시하고 관리할 메인 페이지(notes.php)를 만듭니다:

```html
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Notes</title>
</head>
<body>
    <h1>Your Notes</h1>
    <!-- Add your code here to display and manage notes -->
</body>
</html>
```

10. notes.php 파일에서 노트에 대한 CRUD 작업을 구현합니다.

11. 액세스 제어를 구현하려면 사용자 인증이 필요한 각 PHP 파일의 시작 부분에 다음 코드를 추가하세요:

```php
<?php
session_start();
if (!isset($_SESSION['user_id'])) {
    header("Location: login.php");
}
?>
```

이렇게 하면 사용자가 로그인하지 않은 경우 로그인 페이지로 리디렉션됩니다.

이 단계를 마치면 노트와 사용자 인증을 위한 CRUD 기능을 갖춘 기본 PHP 웹 애플리케이션이 완성됩니다. 페이지 매김, 검색, 정렬과 같은 기능을 추가해 애플리케이션을 더욱 향상시킬 수 있습니다.