February 2026 — In Hyubbbb/Daily_SQL, delivered two SQL modules to strengthen cohort analytics and product-level revenue insights. Key features: 1) Monthly Purchase Ratio Calculator for 2021 joiners, implemented with a GROUP BY to eliminate duplicate counts. 2) Product-level Sales Analytics and Aggregation, added missing sum function and optimized ordering/grouping for clearer, more accurate analytics. Major impact: improved data quality and reliability of cohort measures and product revenue reporting, enabling better business decisions and faster reporting. Technologies/skills demonstrated: SQL module development, query optimization, aggregation logic, and cross-team collaboration (hyunjin.sql scripts; contributions from 임현진).

January 2026 delivered two major feature sets in Hyubbbb/Daily_SQL along with targeted fixes, resulting in richer data access, improved query clarity, and better operational visibility. 1) Book Catalog Data Retrieval Enhancements: added comprehensive book details (including author), improved query clarity and consistency, and enabled flexible category-based filtering (경제) and publication-date ordering. Implemented via a dedicated hyunjin.sql script with iterative refinements (commit history includes Create hyunjin.sql, Update hyunjin.sql, various submissions, and style adjustments). 2) Animal Status Tracking: Check-in/Check-out Status Queries: introduced SQL queries to monitor animal status, including records checked in but not checked out and related status queries, enabling better inventory and workflow insights. 3) Bug Fixes and Quality: fixed issue #9 in the Book Catalog feature and continued code hygiene through structured commits. Overall impact: faster, more reliable catalog lookups with richer data and ordering capabilities, improved filtering for business insights, and enhanced visibility into animal-status workflows. Technologies/skills demonstrated: SQL scripting and query optimization, data retrieval enhancements, version-control discipline with clear, localized commit messages, and cross-functional collaboration.

September 2025 monthly summary for team-epoch/EPOCH_4th_TASK: Delivered foundational setup and repository hygiene enabling rapid experimentation and onboarding. Key features delivered include initial project scaffolding and assets uploaded to establish a baseline for notebooks and resources, plus the bootstrap commit adding initial project files. Major bugs fixed involve cleanup of Pilot/week1 notebooks by removing outdated and duplicate files for user 임현진, addressing potential confusion and improving reproducibility. Overall impact: created a stable foundation for future work, reduced onboarding time, and improved repository cleanliness and reproducibility of experiments. Technologies and skills demonstrated include project bootstrap, mass file uploads, disciplined version control, notebook/file management, and cross-team collaboration.

August 2025 (2025-08): Delivered end-to-end ML features for team-epoch/EPOCH_4th_TASK with a focus on business value, predictive insights, and code hygiene. Key outputs include an Insurance Cost Prediction Model (linear regression) featuring data loading, preprocessing, training, prediction, evaluation, and interpretation of coefficients to enable price estimation and risk assessment for customers. Also delivered a Diabetes BloodPressure Prediction Notebook using a baseline linear regression approach with train/test splits to surface driver factors and health insights. Improved repository hygiene by removing an outdated Practice notebook to reduce confusion and maintain a clean, maintainable material set. These efforts enhanced data-driven pricing, health insights, and overall project maintainability.