hyelie Portfolio

HYEIL JEONG

Backend Developer

Hello, I'm Hyeil Jeong.
A tenacious backend developer.

About Me

My goal is to become a developer who has a good influence on people, thus I always struggle with how to achieve my goal. Recently, I have been interested in clean architecture and refactoring.

I never leave broken windows unattended.

I always struggle to improve performance and code quality.

I use rigorous proof to make the best decision for the situation.

I prove the tradeoff of all cases by tight logic and experiment in order to make the best choice.

	Language
	Java

	Framework
	Spring Boot

	Database
	MySQL

	DevOps
	Docker Jenkins

	Collaboration
	Git Figma

Experiences

Army Headquarters

Software Engineer

February 2022 ~ August 2023

Maintained web application server written in eGovFramework(Spring)
Fixed security issues such as XSS, SQL Injection, path traversal, and web shell
Liquidate legacy code through refactoring such as database normalization, removing redundant code.
Served military service as a SW engineer, honorably discharged as a sergeant
Related posting
- Query optimization 🔗
- Secure coding (XSS, SQL Injection, path traversal, web shell) 🔗

Spring

Java

JSP

Secure coding

Refactoring

Software Maestro

Backend & DevOps Developer

April ~ December 2021

Successfully finished a B2B Project Bizkicks with two other members
Contacted 20 companies for partnership contract
Validated product-market fit through meeting with Kakao Entertainment, Start Run, Danbee, and Spring Camp
Signed MOUs with XingXingMobility and Snack24
Strengthened business capability through experience from proposal to commercialization
Related posting
- Software Maestro 12th activity memoir 🔗

Business

B2B

Naver Boostcourse

Coding Coach

January ~ February, July ~ August 2021 (6 weeks each)

Acted CS50(C) , PY4E(python) course coach
Helped mentees' with technical difficulties
Reviewed mentee's code, evaluated and gave feedback on their assignments

C/C++

Python

Tistory

Tech Blog

July 2020 ~ present

Organized technical concerns and computer science
Post as deep and rigorous as possible
Blog link (in Korean) 🔗

POSTECH

Department of computer science and engineering

February 2018 ~ present

Currently attending in 8th semester, taking 1 credits. (total 127/128)
Cumulative GPA 3.71/4.3 (94.1% percentile)
Won a full scholarship and 2019 Global Leadership Program scholarship
Cheero, postech cheerleading club (2018 - 2020, served as president of the club)
- Cultivated community consciousness, leadership, and communication
Poapper, App development club (2020)
- Managed project Pocarpool

Bizkicks

Integrated shared kickboard service

Backend

DevOps

@Software Maestro 12th

Implemented the API (kickboard location, notification, consumption feature CRUD)
- Connected MySQL using JPA
Established authentication system
- User authentication using Spring Security and JWT
- Mail authentication using Redis, UUID, and SMTP
Configured Jenkins CI pipeline and deployed through GKE
Applied Git Flow strategy
Technical considerations
- Conversion position between DTO and Entity 🔗
- How to solve JPA inline view 🔗

Back-End	Spring Boot JPA MySQL Redis JWT
DevOps	Docker Jenkins K8S SonarQube GCP
Collaboration	Figma GitLab Notion

GitHub

Meerkat

Military secure chat application with E2EE

Full Stack

@2022 Osam

Designed the backend MVC structure, implemented the API for the app (friend, clear report, chat room feature CRUD)
Designed and implemented chatting structure
- Real-time chat and offline handling using Socket.io
- Real-time update of chat room list status and users who have read the messages.
- Devised how to apply end-to-end encryption to the application
Applied GitHub Flow strategy and stash-fetch-rebase merge
Annotated all functional units with jsdoc
Technical considerations
- How to implement real-time chat 🔗

Front-End	React Native TypeScript
Back-End	Node.ts Express MariaDB Docker
Collaboration	Figma GitHub

GitHub

Naver2Tistory

Blog migration automation CLI tool for NAVER TO TISTORY

@Open Source

@Personal Project

Developed to solve the pain in migrating blog posts
Parsed and inspected URLs using regular expressions
Crawled Naver blog posts and converted to Tistory format
Constructed an expandable architecture through refactoring and wrote unit tests
Technical considerations
- Refactoring history 🔗

Stack

Java

GitHub

Demo

GitHub

Pocarpool

Postech carpool application

Team Leader

Backend

@2020 UGRP

Implemented the API for the app (room list, report feature CRUD)
Implemented online chatting using socket.io
Documented the API on Excel
Documented issues and milestones on GitLab
Learned the importance of having a clear goal as a team and how to cope with scheduling amongst multiple teammates

Back-End	Node.js Express MySQL
Collaboration	GitLab Excel

GitLab

NIPA prize

OSAM

2022

Awarded for project Meerkat at the 2022 OSAM hackathone

GitHub

detail

SQLD

Korea Data Agency

2022

Nationally recognized certification for Database SQL

detail

Information processing engineer

Ministry of Science and ICT

2021

Nationally recognized certification. Verifies the ability to perform project tasks throughout the entire life cycle of information systems

detail

Participation prize

POSTECH

2020

Awarded for project Pocarpool at the 2020 POSTECH undergraduated research program

GitHub

detail

GLP

POSTECH

2019

Excellent student scholarship in POSTECH computer science and engineering department

detail

Feel free to reach out if you want to know more about me or my work. (or even building something together!) I would be more than grateful to hear from you.

Seoul, Republic of Korea