Ratings
2018-04-27: 27th Korea Championships(Korea)
| SEO Youjoon | 28-36 | LEE Chunae |
| KIM Dongkwon | 32-32 | SEO Youjoon |
| SEO Youjoon | 19-45 | KIM Younghun |
| KIM Youngbum | 42-22 | SEO Youjoon |
| SEO Youjoon | 41-23 | PARK Jonghyun |
| SHIN Dongmyung | 27-37 | SEO Youjoon |
2017-08-26: 1st Incheon open(Korea)
2017-06-18: 3st myeongin(Korea)
| KIM Jungho | 16-48 | SEO Youjoon |
| SEO Youjoon | 36-28 | KIM Dongsu |
| OH Joungmok | 47-17 | SEO Youjoon |
| ASAHINA Satoshi | 45-19 | SEO Youjoon |
| SEO Youjoon | 51-13 | KIM Youngsuk |
| SEO Youjoon | 48-16 | KIM Dongkwon |
| SEO Youjoon | 27-37 | SUEKUNI Makoto |
| SEO Youjoon | 29-35 | KIM Kwanyoon |
| KIM Gyejin | 07-57 | SEO Youjoon |
| SEO Youjoon | 49-15 | PARK Jonghyun |
| KIM Dongil | 23-41 | SEO Youjoon |
| SEO Youjoon | 28-36 | SOHR Jaeyoung |
| SEO Youjoon | 34-30 | LEE Chunae |
| KIM Donggyu | 31-33 | SEO Youjoon |
2009-07-26: 14th KoA Championships 2009(Korea)
| SEO Youjoon | 32-32 | HA Seungsup |
| YU Yoseop | 51-13 | SEO Youjoon |
| SEO Youjoon | 11-53 | HWANG Yoonjoo |
| SEO Youjoon | 38-26 | LEE Geuncheol |
2007-11-29 → 2007-12-01: WOC 2007 (Athens)(World)
2007-05-21: 7th Korean Othello Open(Korea)
| STASTNA Jan | 24-40 | SEO Youjoon |
| BERGLUND Caroline | 36-28 | SEO Youjoon |
| SEO Youjoon | 40-24 | WOZNIAK Agata |
| SEO Youjoon | 55-09 | DOLEZAL Vladislav |
| TOMEI Robin | 21-43 | SEO Youjoon |
| SEO Youjoon | 25-39 | SEELEY Ben |
| HIRVONEN Patrik | 56-08 | SEO Youjoon |
| SEO Youjoon | 26-38 | KRAIKOKIT Thammatorn |
| YU Yoseop | 34-30 | SEO Youjoon |
| SEO Youjoon | 17-47 | KRACZYK Roman |
| KLOCKARS Daniel | 26-38 | SEO Youjoon |
| SEO Youjoon | 41-23 | ANDRIANI Bintsa |
| BECK David | 34-30 | SEO Youjoon |
| JUNG Taejoon | won against | SEO Youjoon |
| SEO Youjoon | won against | LEE Jiseung |
| SEO Youjoon | won against | LEE Chunae |
| OH Joungmok | won against | SEO Youjoon |
| SEO Youjoon | won against | HA Seungsup |
| JUNG Taejoon | won against | SEO Youjoon |
| YU Yoseop | won against | SEO Youjoon |