DEV Community: Chaesang Jung

Orthogonal: The Word That Taught Me to Cut Things Apart

Chaesang Jung — Tue, 30 Jun 2026 03:46:26 +0000

The second word a professor told me to carry for life. It took me years — and a lot of vectors — to start understanding it.

A look back — long before any of the tools we argue about now.

The same professor — Sang Lyul Min — handed us these words one at a time in lecture. After trade-off, two more stuck with me. But before the second word itself, here are the two pieces of news he brought to class around then. The internet barely existed; information moved through journals, magazines, and word of mouth. Looking back, it's a little amazing how much still got through.

When a chess machine started winning

The first breakthrough I remember: computers had finally started playing chess on roughly even terms with the world's best. Deep Blue beat Kasparov around 1996, so the machines he was describing came just before — names like Deep Thought, ChessMachine, Socrates II. He told us, deadpan, that one human competitor's head had "physically burst" from the strain — and we groaned, "Come on, Professor, that's a bit much."

We live on the far side of AlphaGo now, so it's easy to forget how much we shrugged at all this back then. I was a decent amateur — a 1-dan at Go, hopeless at janggi (Korean chess) against any program — and I still remember the hollow, slightly bitter feeling the AlphaGo era left even in someone who only ever played for fun.

A full-body scan

The second: in the US, death-row inmates had consented to the first dense full-body image scans. That was the news that taught me — embarrassingly late — that this kind of computing could reach all the way into medicine. Computers, it turned out, showed up in the strangest places.

orthogonal

Back to the words. The second one, the professor said, would run through my whole career: orthogonal. The Korean rendering — 직교하는, "at right angles" — was, naturally, a word I'd never heard. The plain-language version was "unrelated, independent." It came back hard years later, when I had to take vectors seriously — first in linear algebra, then in ML and AI.

If trade-off was his word for engineering, orthogonal was his word for the researcher's method: the thing that makes a proof, or an argument, easy to make. Recently, while prepping AI/ML lectures, I met matrices and vectors again — their particular discomfort, and the cleanup that comes after something like matrix factorization lops dimensions off — and found myself reaching back for this word.

I still haven't accepted it all the way down; I'm still learning it. It lives mostly in research and papers — in hypotheses, verification, methods you can trust — where half the job is cutting away what isn't related. Real-world data never splits as cleanly as you'd like. But the method is to prove your way down, lowering the dimensions, peeling off the things that have nothing to do with each other. When what's left is two or three dimensions, your eyes and your head can finally follow along. I still remember the small thrill of watching a little universe of three-dimensional somethings — orthogonality proven — collapse into one or two clean dimensions.

Adapted from my Korean essay on Brunch: brunch.co.kr/@chaesang/34

Trade-off: The First Word I Was Told to Carry for Life

Chaesang Jung — Mon, 29 Jun 2026 05:13:01 +0000

Before I understood what engineering was, a professor handed me a word to look up in a dictionary. I've been using it ever since.

A look back — long before any of the tools we argue about now.

Engineering, before I knew the word

In Korea, boys in middle school took a subject simply called "Technology," and high schools offered an elective called "Industrial Arts." Mine taught "Commerce" instead — so my entire pre-college image of engineering came down to a screwdriver, a few nails, and an AM radio kit I'd soldered together. No Lego that I can recall, but I remember playing with science kits, and blowing my allowance on Academy plastic models. The closest thing to "advanced study" was learning to read resistor values off their color bands — black, brown, red, orange, yellow, green, blue, violet, gray, white. That was the whole of my hardware education.

I walked into a computer engineering department without ever really asking myself what engineering was. What I noticed first, honestly, was the gender ratio: about one in ten classmates was a woman, which — after six years in all-boys middle and high schools — was its own small culture shock. Having women as classmates and seniors at all felt like news.

The first word

Our first major course was "Introduction to Computer Engineering," which in practice meant learning C. We could finally touch the machines at school; you did your homework in Turbo C and handed it in on a floppy.

I can't forget Professor Sang Lyul Min, one of the second class our department ever graduated. One day he said, "Let me give you a few fundamental words you'll need for the rest of your life." The first was trade-off. This was before the internet was something you could just search, so I went home and dug it out of a Korean–English dictionary, like a piece of slang I'd never heard.

From that one word I learned three things at once: that there's no free lunch; that this is exactly where engineering parts ways from science; and why the comparison with mathematics would keep coming back. The further I went into my career — and the more decisions I had to actually own — the more that word kept surfacing.

The word that kept coming back

It showed up in my algorithms course, the moment we started weighing time complexity against space complexity. It showed up again and again as I began reading papers, as a way of making sense of the world. If someone asked me today what engineering is — or made me pick a single word for it — I wouldn't hesitate.

I'd say: trade-off.

Adapted from my Korean essay on Brunch: brunch.co.kr/@chaesang/32

Lode Runner, Ultima, and a Samsung Tape Drive

Chaesang Jung — Sat, 27 Jun 2026 20:17:49 +0000

Before I studied computer science, there was a contest in Busan, a cassette that loaded games, and code I typed in from a magazine.

A look back — long before any of the tools we argue about now.

These episodes come from studying computer science in Korea in the 1990s. But the memory starts a few years earlier, with a handful of words from the 1980s.

A personal-computer contest

In 1985, my elementary school in Busan ran an after-school class to pick kids for a math competition. That year the regional district math contest happened to be discontinued, so the class was quietly converted into a computer class instead — and that's how I first met a personal computer, and the idea of a contest built around one. It was probably an early ancestor of today's programming olympiads. I got lucky: in 1986 I went up to Seoul for the first time, to a place called Jamsil, as one of Busan's representatives. Picture a large hall where each kid hauls in their own computer and sits an exam for four hours, a little like candidates at an old civil-service examination. To get there you had to win your way through the district round, then the Busan city round.

My first time out, a bug knocked me out — a real heartbreak. Trying to get past it, I took several more runs at the regional contests through the eighth grade, and along the way I picked up some real skill — and got a lot friendlier with computer games. I never made it back to the national round, but I climbed to first in the district at my last contest. A reasonably happy ending.

The Samsung SPC-1000

The first Samsung product in our house was this computer. I'd run into one at school, and after I earned the ticket to the national round in Seoul, I begged my parents until it followed me home. The strange mechanical whir of loading from a cassette tape; the games that started once the whirring stopped; the small charms of dots arranged across a black-and-white screen. It saw me through elementary school, came with me to every contest, and gave me my first taste of disappointment and failure.

Computer Study

This was the first reason I had to get — or earn — an allowance every month. There was a sister magazine too, Students and Computers, and some months I'd agonize over which of the two to buy; there were fancier books around, I remember. The content was a fair mix of fun pieces, new technology, and games. But what really mattered about this magazine was the source code. Typing those listings in, line by line, built a patience I didn't notice I was building — and it paid off later.

The Apple II+

I begged for a new one in middle school, ostensibly for the contests. I don't remember exactly which model it was — maybe a IIe. I loved the clack of that keyboard, and it's where I first stepped into the new world of the floppy disk. The contests were the pretext; honestly, I was one step from full game addiction.

Lode Runner, Ultima 4, Ultima 5, Ogre

The companions of my middle-school years. Lord British, thou art, and an endless vocabulary of game spells, ingredients, weapons, dragons…

After that I shifted into exam-prep mode, head down for college entrance, and that's how I walked into the 1990s.

Adapted from my Korean essay on Brunch: brunch.co.kr/@chaesang/30