출처
https://curryyou.tistory.com/441
https://curryyou.tistory.com/442?category=898979
https://wanago.io/2021/11/01/api-nestjs-storing-files-postgresql-database/ // API with NestJS #54. Storing files inside a PostgreSQL database -- Buffer 라는 타입이 있음.
https://yceffort.kr/2021/10/understanding-of-nodejs-buffer -- nodejs의 버퍼 이해하기