Web & Mobile Developer
Ju-cheol Park
- Experience
- Triphos Co., Ltd. / 2026.02 ~ Present
- Scope
- Built web interfaces and server APIs, and integrated Android app features
Selected work
01 Settlement ERP Platform
Built the ERP web app, key server APIs and data persistence, with shared editing tables, batch Excel imports and administrator work logs.
02 Logistics Operations Web and Printing App
Built search, reservation and Excel-import screens, API integration and Android label printing. Reduced the initial JavaScript entry file by about 74% (build output size).
03 Stock Operations Admin Web
Built the complete React frontend using MSW mock APIs, with shared tables and query-state handling for account, stock and order screens.
Next, I will introduce daily information and privacy apps, an internal documentation tool, further company work, and personal and team projects.
Company work 01
Settlement ERP Platform
A business system for vehicle and driver records, transport fees, billing, and settlement. Built the ERP web app and key server APIs, and extended the existing user-facing web and mobile apps.
Technologies
- React,
- TypeScript,
- Tailwind CSS,
- Vite,
- React Router,
- Zustand,
- Spring Boot,
- MyBatis,
- MariaDB,
- Vitest
From data entry to batch saves
Editing tables that retain input
Built keyboard cell navigation, selection dialogs, and per-row save feedback, retaining edits in rows that fail to save.
From Excel preview to persistence
Highlighted invalid Excel rows and cells for correction and revalidation. Rolled back failed batch imports and returned existing results for repeated requests.
Record changes and settlement history
Separated current assignments from historical transactions to retain finalized settlement amounts. Vehicle save feedback identifies newly created records, operating-status changes, and affected insurance or utility records.
Logs showing actions and errors
The initial logs captured many details, but technical fields made it difficult to follow what had happened. I surfaced affected records, changes, and input-error reasons, and removed unnecessary technical fields.
Company work 02 / Web
Logistics Operations Web
A logistics web app for search, reservations, Excel imports, and label printing. Built the complete frontend with React and TypeScript, including server API integration and PC label printing.
Technologies
- React,
- TypeScript,
- Vite,
- React Router,
- TanStack Query,
- Zustand,
- XLSX,
- Vitest
Business interfaces and printing
Shared interfaces and API integration
Built shared tables, forms, and modals, connecting server APIs to workflows from search and reservations through Excel previews and print requests.
Long addresses on printed labels
Wrapped PC label addresses by measured text width and fitted the remaining address into the final line.
Load only the code needed on entry
The initial bundle included multiple pages and heavy Excel code that users did not need on their first screen.
Identified code that was unnecessary on entry and loaded pages and Excel libraries only when needed.
Bundle size change
- Initial JavaScript entry
2,405.50 → 616.59 kB
About 74% smaller on the same build basis
- Gzip-compressed size
815.10 → 204.38 kB
About 75% smaller for the same initial entry
Scope of code splitting
Also evaluated splitting shared authentication and API initialization code. This reduced the initial file size further, but complicated authentication initialization and loading on the first interaction, so I did not adopt it. Applied lazy loading only to pages and Excel libraries.
Company work 02 / Android
Logistics Label Printing App
Connected web label-print requests to an Android app and Bluetooth printers.
Technologies
- Expo,
- React Native,
- Expo Router,
- WebView,
- Android native module,
- TypeScript,
- Bluetooth
Context
Web print data needed to reach a native device SDK while the interface handled permissions, connection, and cancellation.
Implementation
- WebView
Label data and print request
- Android
Bridge, permissions, device connection
- Bluetooth
Printer SDK and label output
From web requests to hardware
Passed print data through a native bridge and implemented device selection, connection, and print calls as a single flow.
Permissions and cancellation
Traced SDK discovery calls on Android 16/API 36 and corrected cancellation and BLUETOOTH_SCAN, BLUETOOTH_CONNECT permission handling.
Outcome
Verified Bluetooth connection and physical label output on an Android device.
Company work 03
Stock Operations Admin Web
Built the complete React frontend for a stock administration web app using MSW mock APIs.
Technologies
- React,
- TypeScript,
- Vite,
- React Router,
- TanStack Query,
- Zustand,
- MSW
Shared tables, filters, and modals
Built shared list, search, detail and editing components for account, stock and order screens. Added column pinning, resizing and reordering to tables, and implemented queries and input interactions with MSW mock APIs.
Applying order-history filters
Kept account and stock selections separate from the conditions applied to the list. Editing a filter retained the existing results; pressing Search applied the submitted conditions to the TanStack Query key.
Repeat searches and load more
Search again with the same filters
Reset the existing query to reload from the first page.
Guard load-more requests
Skipped additional requests when no next page remained or a request was already in progress.
Company work 04
Weather in a Daily Information App
Added public-data weather features to an existing Android app, implementing the WebView interface, server-side API integration, and caching.
Technologies
- Spring MVC,
- JSP,
- jQuery,
- Java,
- Android
Weather data across separate APIs
Weather, air quality, and alerts had different regional coverage and update schedules. Fetching everything on every visit repeated requests for the same area and could hold up available information while a slower response arrived.
Caching by region and data type
Reuse data for requested regions
Cached responses by region and data type, with expiry periods matched to each type.
Share in-flight requests
Reused an in-flight result for the same cache key rather than issuing another external API call.
Show core information first
Displayed current conditions and the core forecast first, then filled in air quality and alerts as responses arrived. Delays or failures in supplementary requests did not hide weather data already received.
Handling stale information
When an external request failed, allowed stale values could remain visible. An expired “no alerts” response was marked unavailable rather than treated as current. Previously retrieved active alerts were labelled as based on the last retrieval.
Company work 05
Privacy Check App
Added email-breach lookup and deepfake image checks to an existing Android app. Connected inspection screens, server calls to external APIs, and Android image selection from input through results.
Technologies
- Android,
- Cordova,
- Spring MVC,
- jQuery,
- Java
Turn external inspection APIs into app features
Implemented server calls to external APIs for submitted emails and images, translating responses and errors for the interface. API credentials remained on the server; the app received the results and status needed for display.
From image selection to inspection
Input validation and preview
Validated file type, size, and resolution, and displayed a preview of the selected image.
Android file selection
Connected image and file requests from the WebView to native selection results.
When the user selects another image
A previous file read can finish after the user selects another image. Assigned a token to each read and checked it on completion so stale results would not overwrite the new preview.
Company work 06
AI-assisted Project Documentation Web App
Built an internal web tool for drafting and reviewing documents from repositories and project kickoff material, covering source collection, table editing, and export.
Technologies
- Node.js,
- TypeScript,
- React,
- AI API,
- xlsx,
- Vitest
Review source material before drafting
Split the interface into review stages for proposed requirements and open questions before drafting final documents. Enabled functional specifications after the requirements document was ready, and screen specifications after their prerequisite documents were ready.
Review tables and revise selected content
Edit document sheets
Displayed requirements, functions, and screens as editable sheets and exported documents from the edited data.
Targeted AI revisions
Sent the selected sheet and cells with surrounding content to distinguish revision targets from context to preserve.
Handle partial generation failures
Tracked generation status per document so completed documents remained available for review after another failed. Supported regenerating and exporting selected documents without restarting the entire set.
Company work
Further company work
Feature additions to existing services and updates for Android versions and field use.
07 Member and Inquiry Management Web and App
Implementation
Extended an existing solution with member search, editing, merging, inquiries, and attachments. Integrated file selection and image previews in the Android app.
Technologies
- Spring MVC,
- Java,
- MyBatis,
- Vue 2,
- MariaDB,
- Android,
- Kotlin
08 Parcel Delivery App
Implementation
Updated map-marker selection, current location and return-to-map behavior. Implemented offline delivery-completion saves, request recovery after app restarts and retries after reconnection.
Technologies
- React,
- TypeScript,
- React Native,
- Expo,
- Spring Boot,
- SQLite
09 Chart Preview Page
Implementation
Built chart settings panels, data connections, and previews as part of a website that was under development.
Technologies
- React,
- TypeScript,
- Vite,
- Chart.js,
- WebGL/GLSL (OpenGL-style),
- OGL (WebGL library),
- MSW,
- Vitest
10 Logistics Receiving and Shipping PDA App
Implementation
Updated an existing PDA app for newer Android versions and added receiving screens, quantity entry, and QR/barcode scanning. Revised the app update download and installation flow.
Technologies
- Android Java,
- Gradle/AGP,
- Scanner SDK
11 Legacy Shipping and Inventory App
Implementation
Updated the build environment of a legacy Android app with a WebView interface, adapting permissions, file access, and back navigation to OS changes. Verified behavior on devices running several older Android versions.
Technologies
- Android Java,
- Gradle/AGP,
- RxJava,
- FileProvider
Project 01
C. Donghae
Built a map-based web service for Donghae Line passengers to find live transport and nearby information.
Technologies
- TypeScript,
- React,
- Next.js,
- Tailwind CSS,
- Google Maps,
- Storybook,
- AWS,
- GitHub Actions,
- Docker
Hackathon scope
The team had 72 hours to combine train, weather, and local-place data in one map with mobile interactions.
Implementation
Maps and API integration
Worked with two backend developers using Swagger documentation to connect APIs and build the main Google Maps screens.
Mobile map interaction
Built a bottom sheet over the map that expands or collapses according to drag distance and velocity.
Award
Won the Busan Technopark President Award at DIVE 2024, placing third in the challenge track.
Project 02
ShareBBy
Developed Android support and community features for an app that helps people share hobbies and find companions.
Technologies
- JavaScript,
- React Native,
- Firebase,
- Faster Image
Android support and image updates
Screens initially built for iOS needed Android support, and stale image caches prevented updated post images from appearing.
Implementation
Community features
Built post and comment editing, location filters, sorting, pull-to-refresh, and infinite scrolling.
Data and image handling
Documented Firebase relationships in an ERD, reproduced the caching problem, and adopted a maintained replacement library.
Release
Delivered Android screens and community features. The team released the app on the App Store in 2024.
Project 03
AI Agent Playbook
Built a harness that helps AI coding tools carry project rules and work history across sessions. Added selected skill installation, migration and recovery while preserving existing files.
Technologies
- JavaScript,
- Node.js,
- MCP SDK,
- Zod,
- GitHub Actions
Context and user-file preservation
Working across repositories required shared records to remain distinct from local history. Updating skills also had to preserve user edits and avoid losing a working setup after a failed installation.
Implementation
Shared records and read-only MCP
Implemented CLI and MCP access to registered repositories’ records. Paginated long responses and rejected continuation after the underlying source changed.
Preserving edits and recovering installations
Checked ownership and file hashes, keeping backups and recovery records. Profile migration requires every selected replacement to be valid and rechecks them before each removal.
Release and verification
Published on npm and GitHub, with installation and usage documented in English and Korean. Tested installation conflicts, partial failures, recovery, query scope and continuation, and configured Windows/Ubuntu CI.
Project 04
Itzip
Built blog and Markdown editing screens in a 15-person team, adding tests and error monitoring to the development workflow.
Technologies
- TypeScript,
- React,
- Next.js,
- Tailwind CSS,
- React Spring,
- Jotai,
- Jest,
- Prisma,
- Storybook,
- Postman,
- Sentry,
- AWS,
- Jenkins,
- Docker
Editing and team development
The team needed a shared way to inspect component behavior and errors after deployment while building the editor.
Implementation
Markdown editing and previews
Implemented live previews and project-specific Markdown syntax, splitting heavy components with dynamic imports.
Tests and error monitoring
Tested key behavior with Jest, documented components in Storybook, and configured Sentry for post-deployment errors.
Team adoption
Delivered blog and editor screens with unit tests, component documentation, and error monitoring.
Project 05
Posture Teacher
An Android app that classifies posture from body landmarks in camera frames and records exercise time.
Technologies
- Java,
- Android,
- Jetpack,
- MediaPipe,
- SQLite
Camera analysis and interaction
Continuous frame analysis needed to remain separate from screen input, and MediaPipe had to be built for the Android project.
Implementation
MediaPipe integration and posture detection
Built a MediaPipe AAR on Ubuntu and used landmark angles and lengths to classify posture and measure hold times.
Separate frame analysis
Moved analysis to a separate thread so camera processing and screen input did not block each other.
Measured result
During the project, frame-processing FPS was 5–10 times that of the OpenCV implementation, measured as frame-processing throughput.
Profile
Skills, education, and awards
Skills
Languages
TypeScript, JavaScript, Java
Web
React, Next.js, Vite, TanStack Query, Zustand
Mobile / hybrid
React Native, Expo, Android, Gradle
Testing / monitoring
Vitest, MSW, Storybook, Sentry
Tools & Data
GitHub Actions, Jenkins, Docker, MariaDB, SQLite
Education & activities
Gyeongsang National University / Computer Science
GPA 3.64 / 4.5
Programmers Devcourse
Cloud Application Engineering, React and React Native
Programmers Devcourse / Assistant Mentor
Shared development resources and supported daily scrums and project reviews.
Awards
DIVE 2024 Global Data Hackathon
Busan Technopark President Award / third in the challenge track
Gyeongnam Software Competition
ESD HotDeal / Top Excellence Award