Hyeonsu (Eddy) Hwang · Seoul, South Korea

An electrical engineer who designs and builds for the web.

I study electrical engineering at Chung-Ang University and work in R&D at an LED manufacturer. Alongside that I design and ship software: a full website rebuild for a manufacturer, a live SaaS product, and the hardware projects below. This page is who I am and what I’ve made.

EEElectronic & electrical engineering
R&Dat an LED manufacturer, Seoul
Full-stackdesign → code → database → deploy
EN · KOworking languages
Background

Engineering first. The building came from needing things to exist.

I didn’t come to the web from design. I came to it from datasheets, test benches and projects that had to work.

2026.07 — nowR&D InternLED manufacturer · Seoul
2025.03 — 2026.03Electrical Team LeadChung-Ang University student-built EV project
2025.04 — 2025.12Co-founder / CTO, hardware & softwareAlzWatch
2025.06 — 2025.08Undergraduate ResearcherElectric Machines Lab (FEM LAB), Chung-Ang University
2021.12 — 2022.02Production Operator, daily contractHyundai Motor Company · Ulsan plant
2021.03 — 2027.02BSc, Electronic & Electrical EngineeringChung-Ang University · Seoul
Current research focus

Battery thermal and safety diagnostics — early detection of Li-ion thermal runaway, state-of-health prediction, and thermal-imaging AI running on embedded hardware.

01

I read datasheets for a living

When someone says irradiance, wavelength, pressure rating, duty cycle or tolerance, I don’t nod politely and then write something vague. I know which number a buyer is actually comparing, and I put that number where they can find it.

02

I’ve moved a decade-old site without breaking it

Anyone can build on a blank page. The hard job is a site running on an old CMS since 2016, with years of product URLs and search rankings you cannot afford to lose. I’ve done that migration — keeping URLs, redirects and indexed content intact while replacing everything the visitor sees.

03

I build the back end too, not just the front

I designed and shipped a live SaaS product on my own: multi-tenant Postgres with row-level security, OAuth sign-in, subscription billing and serverless APIs. So a customer login, a product catalogue or a payment flow doesn’t become “outside my scope” — it just gets built.

04

I sit between Asian manufacturing and Western buyers

I’m based in Seoul and work in Korean and English. I know how an Asian manufacturer describes its own product, and how a European or North American buyer needs to read it. Those are not the same document, and translation alone does not bridge them.

Selected work

One rescued a decade-old manufacturer site. One is a SaaS product I built and shipped myself.

Real screens from real work, not template previews. Client identity anonymised on request.

LED horticulture manufacturer — full website rebuild

A B2B manufacturer selling grow-light systems to greenhouses and vertical farms. Their site had not been touched since 2016: a legacy PHP shopping-mall CMS, jQuery 1.8, broken on phones, duplicated menus, and 21 tracking scripts slowing everything down.

The real problem was deeper than the design. A grower choosing a lighting system compares wavelength mix, PPFD at a given mounting height, coverage area and power draw — and none of that was reachable without downloading catalogues. So buyers phoned the sales team to ask questions the website should have answered, and the ones who didn’t phone simply went to a competitor. I could diagnose that because I work in R&D at an LED manufacturer myself; a designer without that background would have redrawn the same site more attractively and changed nothing.

I also built the two pieces that decide whether a site earns its keep after launch. A quote form that asks the four questions the sales team actually needs — crop, growing area, facility type, contact — and delivers them as a formatted email in the owner’s inbox, ready to reply to. And an admin panel, so the client publishes news, installation cases and products themselves: write, upload photos, reorder, unpublish. No developer, no invoice, no waiting for me.

B2B manufacturingFull redesignInformation architectureMega menuMobile-firstAdmin panel (CMS)Quote form → email7 pages
RoleResearch, UX, UI, front-end
ScopeHome + 6 inner pages
DeliverableLive site + admin panel the client runs
TimelineIterative, ~3 weeks of build
Before
Original website: dated 2016 layout, not responsive
After
Redesigned homepage: video hero, clear value proposition, mega menu

01 · The pages a buyer actually uses specs on the page, not in a PDF

Live homepage: video hero and one sentence stating what the system does
Homepage — what the system does, in one sentence
Technology page: chlorophyll absorption spectrum and photosynthetic response curves
Light quality — absorption spectrum and response curves
PPFD requirement table by crop
PPFD by crop — comparable figures, no download
Product range page: each fixture beside its wattage, spectrum and coverage
Product range — wattage, spectrum and coverage per model
Installation cases mapped by region with counts per province
Installations — mapped by region, filterable by crop
News page published by the client through the admin panel
News — posted by the client, not by me

02 · The admin panel the client runs no developer, no invoice

Admin console listing news, installation cases and products
Console — publish, reorder, hide. Nineteen posts run through it
Edit screen with required fields only
Edit screen — fill the starred fields and it is live
Written manual for someone who has never used a CMS
Written manual — for someone who has never used a CMS

03 · Enquiries that arrive ready to answer numbers, not “please contact me”

Quote request form asking crop, growing area, canopy height and facility type
The form — crop, area, canopy height and facility type, asked up front
The same enquiry arriving in the owner's inbox as a formatted email with call and reply buttons
The same enquiry in the owner’s inbox, with call and reply buttons

Two buyers, two routes inA grower thinks in crops; a distributor thinks in model numbers. A dual-axis mega menu replaced two duplicated menus so each reaches the right page in one click, instead of guessing.

Specs became comparableTechnical data moved out of downloadable PDFs and onto the page as structured tables — readable by buyers without a download, and by Google for the exact spec terms people search.

Enquiries arrive ready to answerThe quote form collects crop, area and facility type up front and lands in the inbox as a formatted email — not a bare “please contact me”, but enough to quote from on the first reply.

The client updates it themselvesAn admin panel ships with the site: log in, write a post, upload photos, drag items into order, unpublish. Most owners are stuck paying someone every time a line of text changes. Here they aren’t, and nineteen news posts and twenty installation cases have been managed through it since launch.

Veil — SaaS product site & web app, built from scratch

My own product, live in public beta. I designed and built all of it — brand system, marketing site, the web app and the backend. The interesting part is the constraint: the personal reflection runs on the user’s device and is never uploaded, while identity and confession records are stored in separate tables so the review record has no user-ID field at all. Multi-tenant Postgres with row-level security, OAuth sign-in, Stripe subscriptions and serverless APIs.

I include it here for one reason. When a project later needs a distributor login, a quote system, a customer portal or online payment, most people selling websites have to say no or bring in a second contractor. This is the evidence that I don’t.

SaaSOn-device AIBrand & design systemEN + KOPostgres + RLSStripe subscriptionsOAuthLive beta
RoleFounder, designer, developer
StackStatic front-end, serverless API, Supabase
MarketsEN · KO
StatusLive public beta
Landing
Veil landing page hero
In-page
Veil product section

One system, two languagesA single shared design system drives the EN and KO sites — localised pricing, payment methods and copy, not machine translation.

Conversion-ledSelf-serve CTA, trust microcopy, social proof and a competitor comparison table, all decided from market research rather than taste.

Real backendMulti-tenant data isolation verified at the database level, plus subscription billing and OAuth wired end to end.

Web studio

If you’re here about a website, that work lives at Mockfirst.

Same person, same hands. I set it up as its own studio so the pricing, the process and the request form all live in one place instead of being scattered across a personal site.

Mockfirst

See your new website first. Pay only if you like it.

You send a URL, I send back a designed homepage before any money changes hands. Fixed prices published on the page, no hourly billing, English or Korean.

Go to Mockfirst ↗ 한국어 →
  • Legacy site rescue without losing search rankings
  • Spec sheets turned into on-page, comparable data
  • Admin panel so your staff edit it without a developer
  • Multilingual export sites, EN · KO and beyond
  • Logins, catalogues, quote systems, payments
Hyeonsu (Eddy) Hwang

Get in touch.

Happy to talk about engineering roles, a project, or anything on this page. If it’s specifically about building a website, going through Mockfirst is faster — you’ll get a designed mockup back instead of a reply asking for your budget.

Email me →