TAYSTUDIO operation notes · tool guides · tech/career · useful posts
Samsung Electronics coding test — 5 attempts across grad school (DX · Samsung Research) and post-employment (DX · DS · Device Platform). 4-hour simulation problems based on Baekjoon/codetree, Python/Java/C++ allowed. Each attempt failed differently: output format omission, language-switch trap, BFS over-engineering. Honest retrospective.
Why does the sample variance divide by n-1 instead of n? Two views — correcting underestimation (bias) and degrees of freedom — to get at the essence of variance.
Connecting the nature of probability through three concepts — uncertainty, variability, and variance — including the intuition for why variance is defined as 'distance from the mean.'
AWS Summit Seoul 2024 — walking the booths and sorting the trends into three buckets: generative-AI serving (chatbots, email, copilots, image-gen), multi-cloud CMP, and API gateway / middleware. 'Ideas converge — UX and performance is where companies actually win.'
A 64-bit unique ID generator that doesn't collide even when many servers generate IDs at once — the design intent of Twitter Snowflake (Sign·TimeStamp·DataCenter·Server·Serial, 5 segments), a Java bit-operation implementation, and a 10,000 TPS test architecture (Nginx·Netty·MongoDB).
Aug 5, 2019 — KAIST Mech Eng grad school written exam: 4 hours (2+2), 5 subjects, 5 problems per set. Set 1: terminal-velocity ODE, Von-Mises stress, rigid-body Work-Energy, Bernoulli+Energy equation, hydrostatic force on curved surface. Passed written, failed interview.
KAIST Mech Eng grad school written exam, Set 2 — Eigenvalue/Eigenvector (3-variable ODE system), full strength-design pipeline, rigid-body Work-Energy, T-v diagram thermo properties, Couette flow Navier-Stokes exact solution.
SK C&C (now SK AX) 2023 H2 new-grad recruitment — coding test (2h, 4 problems: sim, DP, sim, SQL aggregation) + SKCT in-depth (1.5h personality) + 1-day interview (group discussion + role/personality). Group discussion was actually fun and burned off the nerves before the role interview. Final offer.
Hyundai Motor 2023 H1 new-grad recruitment for CarCloud role — aptitude + AI interview (ViewInter, 12 questions) + coding test (Softeer, Java, 3 problems) + 1st interview (30-min pre-assignment + technical 1:3). Self-graded 4/6 well-answered; still rejected at the 1st round. Keyword recap: API Gateway, WebFlux, encryption.
LG Electronics 2022 H2 new-grad recruitment for R&D Campus in Gasan (H&A division) — coding test (Programmers, Java, 3 problems, two perfect + one partial) + aptitude + 1st interview (master's/PhD research presentation, 6-page PPT) + 2nd interview (executive + English OPIc) → final rejection. A case where job-role misalignment drove the result.