Working on Blizzard Entertainment's Battle.net platform.- Implemented max rate metrics for telemetry with dropwizard/micrometer, which allows enigneer to see what was the maxium peak call volume in second per last N seconds. (2021)- Introduced git-crypt based secret management and removed all types of plain/unencrypted credentials/certs in the department Git repo with automated encryption/decryption with git operation. (2021)- Evaulated and suggested HashiCorp Vault replace with AWS/GCP Secret Manager solution and MVP implementation. (2020~2021)- Migrated legacy in-house rpc error response message builder to use new rpc-error-builder (2020)- Implemented alerts for multiple metrics on in-house ELK solutions. (2019) - Implemented oauth2 use case to support the oauth2 Spring security context population in an async job, thread pool, and async caching load in Google Guava (2019)- Upgraded internal payment systems that talk with 3rd party to use TLS secure endpoint and all the follow-up. (2018)- Added a layer in existing systems to solve the oauth2 scope issue between inter-service calls. (2018)- Replacing the old authentication system to OAuth2 in Battle.net ( Aug 2017 ~ present ), including all the coordination between teams and update all the relative libraries. - Dockerized Battle.net's backend middleware. ( May 2017 ~ Nov 2017 )- Supporting other teams by adding Java backend side OAuth2 support for API Gateway request, including custom proto-maven-plugin to generate Java source from Google Protobuf definition, Spring Security filter to handle authentication, and propagating the authentication instance for the remote RPC call, etc.- Removed heavy cross-region JDBC call between regions and instead introduced a lightweight WebSocket based call between the app based on the shard id, and updated all existing APIs to use this new feature without any service downtime or interruption. ( 2016 )- In-game purchase feature for game teams ( 2014 ~ 2015 )

Worked as Web Software Engineer in web community team, mainly focused on feature development and maintenance of CMS/community blog & forum search/etc.From April 2012, changed a team and worked at Battle.net team, focused on feature developing/maintaining middleware backend which provides game account creation, payment, etc.

- Worked as senior web software engineer at Blizzard Entertainment Korea.- Mainly focused on Blizzard Korea game account services, payment, value added service, KR personal verification by IPIN/Credit Card/SSN/etc. (kr.battle.net/account or worldofwarcraft.co.kr)

• Mentored 9 students in Kookmin University's Fall Global PBL Program, teaching fullstack tech stack and software development fundamentals.• Guided project teams in Agile methodology, Scrum/Kanban, and Jira usage for efficient project management.• Taught Flutter, React Native, Express, and more, fostering students' skills in product ownership and development roles.

-Developed Voucher Management System for PT.Telkom Flexi Indonesia. PT.Telkom Flexi Indonesia is No1 CDMA mobile carrier in Indonesia and have more than 20 million subscribers. My main role was as project manager, but I also worked as developer and helped other developers for performance tuning/QA/web development. It was $1,000,000 project and successfully delivered to PT Telkom Flexi Indonesia. ( 4~5 Uangel developers, 3 outsourcing developers, 2 third party vendor employee, 2 PT Unagel Indonesia local employee ) -Developed MMS(Multimedia Messaging Service) web service / gateway server / billing for SK Telink. Worked as server side backend Java software engineer, developed server part as well as frontend SMS phone UI with javascript/ajax, database modeling/tuning for service/billing, etc. Also performed Oracle database / server app performance tuning.-Developed several major ASP(Application Service Provider) service for SK Telecom. SK Telecom has been top mobile carrier in South Korea and has more than 25,000,000 subscribers. Ringbell tone/Picturemate/LiveBell(mobile phone background img) CMS/billing/download server.Stock information system.Developed entire Key-JJang Friend system.Stock Investment Information system for three major S.Korea mobile carrier. ( SKTelecom, KTF(Olleh), LGT(LG U+))

Built a location-based service authentication server and gateway for 3rd-party providers and mobile carriers (LG Telecom, now LG U+). Developed the gateway, service operation control software, and COM+ web UI.Worked on LG Telecom’s Content Management System, focusing on the Project Management System. Similar to modern issue trackers like Jira but without bug tracking, it was built with ASP and Microsoft SQL Server.Developed Qualcomm BREW applications for KTF (e.g., Mobile Couple Forecasting, Fortuneteller), including server-side implementation in C/C++ on FreeBSD and support for BREW client modules.

worked as a software engineer on various projects, including a Korean language indexer, search engine, and web/intranet document crawler for a solution called MyFinder. My role involved customizing MyFinder for clients like Sony Korea Customer Center, GS Caltex, and the Republic of Korea Navy. I primarily used Servlet and early JSP for web development, Oracle for databases, and Borland C++ Builder for handling intranet MS Office documents.I also contributed to a webmail solution, which featured email-based services and a personal assistant powered by the Microsoft Agent API.