Contributed to the React-Native(+JS) engineering at SendbirdCalls SDK for React-Native: https://github.com/sendbird/sendbird-calls-sdk-react-native- Designed and developed a native module architecture for interfacing with React-Native.- Implemented direct call functionality for seamless integration between React-Native and native code.UIKit for React-Native: https://github.com/sendbird/sendbird-uikit-react-native- Designed the architecture of the UIKit library, providing chat UI components for React-Native.- Implemented core features to support complex UI elements such as gesture recognition, animations, mentions, and customizable styles.Chat SDK for JavaScript​:- Provided engineering support for React-Native, including troubleshooting, bug fixing, and feature enhancements.- Enabled modularization of the chat SDK v4 for tree shaking support by providing technical support using TypeScript. Built a custom type definition bundler using API Extractor and the TypeScript compiler.Chat AI Widget: https://github.com/sendbird/chat-ai-widget- Integrated CI/CD for product stability, enhancing product features and improving performance.Other Contributions:- Selected and extracted common parts from UIKit for React/React-Native and proposed and implemented a monorepo for a common core module. This resulted in resource savings through a single codebase, reduced dependencies on Chat SDK, and improved stability through unified testing.- Improved ticket automation in the deployment process by developing it as a single source. Changed the process from setting up long CI scripts in all repositories to simply adding a single GitHub Action (300+ lines of script reduced to just 17 lines). Achieved easier maintenance through a single source code.

Separation of Staging/Production Environments:- Android: Utilized build variants to achieve separation of environments.- iOS: Used schemes and configurations for the separation of environments.- Separated application and deployment workflows by environment.Improvement of Automation Workflows:- Web deploy: Migrated from Firebase Hosting to AWS Amplify.- Server deploy: Migrated from GitHub Actions (+PM2, AWS CLI) and EC2 (+ELB, ASG) to AWS CodePipeline, Elastic Beanstalk.- Certificates: Migrated from Let's Encrypt to AWS Certificate Manager.- Mobile app: Incorporated a CircleCI approval job and a Slack interaction button for the production deploy.

Mobile Application- Developed SOUNDGYM's mobile application using Typescript, React-Native, and MobX.- Built the application from the ground up, including features such as deep-linking, notifications, in-app purchases, audio/video streaming, dark mode, and integration with Apple HealthKit.- Implemented real-time interaction between users during exercise using silent notifications, as well as many other features.- Contributed to 90% of the codebase up until version 3.15.x.Watch Application- Created SOUNDGYM's Apple Watch application using Swift and SwiftUI.- Implemented features such as streaming, content downloading, content editing, and integration with Health and SOUNDGYM applications.- Supported all watch complication types.- Contributed to 100% of the codebase.Backend Application- Built a subscription managing server for PlayStore and AppStore with server-to-server notification.- Designed 100% of the application structure and implemented 100% of the iOS features, as well as 50% of the Android features.Infrastructure- Applied Cloudfront to S3 resources and implemented on-demand resizing using Lambda@edge, reducing AWS traffic and saving costs by over 40%.- Supported HLS encoding automation and VOD deployment using video-on-demand-on-aws from AWS-labs.In-house/Back-office Work- Automated data collection and generation and collaborated with Hanwha Life-Plus.