Generally, in the previous researches, it is found that a water droplet is respectively in Wenzel and Cassie-Baxter states on hydrophilic/hydrophobic rough surfaces. And Wenzel and Cassie-Baxter equations are used to estimate the apparent contact angle on the surfaces. However, difference between measured apparent contact angle and estimated apparent contact angle with the equations is recently reported and new model to estimate apparent contact angle on rough surfaces is proposed. In this study, wetting state and apparent contact angle on the surfaces with micro-pillars should be investigated to find solution of this argument. Using the high resolution microscope, the wetting state of the D.I.water droplet on the surface with micro-pillars was visualized and apparent contact angle of the D.I.water droplet was measured. On the basis of experimental data, the equations to estimate apparent contact angle were verificated and the general wetting characteristics on the surfaces with micro-pillars are finally classified.

Abstract
 1. 서론
 2. 겉보기 접촉각 이론식
 3. 시편제작 및 실험수행
 4. 실험결과 및 토의
  4.1 48°> θ0 영역에서 액적 젖음성 상태
  4.2 48°< θ0 <180°영역에서 액적 젖음성 상태
  4.3 48°> θ0 영역에서 겉보기 접촉각과 이론식의 비교
  4.4 48°< θ0 <180°영역에서 겉보기 접촉각과 이론식의 비교
  4.5 마이크로 기둥 구조를 가지는 표면에서의 젖음성 특성
 5. 결론
 후기
 References

• 유동인(포항공과대학교 기계공학과) | Dong In Yu
• 박현선(포항공과대학교 첨단원자력공학부) | Hyun Sun Park
• 김무환(포항공과대학교 첨단원자력공학부) | Moo Hwan Kim
• 안호선(인천대학교, 기계시스템공학부) | Ho Seon Ahn Corresponding Author