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이중호(J.-H. Lee),성형진(H. J. Sung) 한국전산유체공학회 2004 한국전산유체공학회 학술대회논문집 Vol.2004 No.-
Direct numerical simulations are performed to investigate the physics of a spatially developing turbulent boundary layer flow suddenly subjected to spanwise oscillating electro-magnetic forces in the near-wall region. The Reynolds number based on the inlet momentum thickness and free-stream velocity is Re_0=300. A fully-implicit fractional step method is employed to simulate the flow. The mean flow properties and the Reynolds stresses are obtained to analyze the near-wall turbulent structure. It is found that skin-friction and turbulent kinetic energy can be reduced by the electro-magnetic forces. Instantaneous flow visualization techniques are used to observe the response of streamwise vortices to spanwise oscillating forces. The near-wall vortical structures are clearly affected by span wise oscillating electro-magnetic forces.
골수술용 초음파 핸드피스 유한요소해석 및 이의 실험적 검증
송태하(T. H. Song),박철민(C. M. Park),이중호(J. H. Lee),이희원(H. W. Lee),최종균(J. K. Choi) Korean Society for Precision Engineering 2021 한국정밀공학회 학술발표대회 논문집 Vol.2021 No.11월
현대 의학에서 초음파는 각종 질병의 진단에서부터 치료기기, 치과용 핸드피스 및 외과용 수술기기까지 다양한 의료 분야에 응용되어 사용되고 있다. 본 연구에서는 골수술용 초음파 핸드피스의 최적화를 위해 유한요소해석(Finite Element Method, FEM)을 통해 개발중인 초음파 핸드피스의 최적 구동을 위한 설계를 확정 하였다. 또한 최종적으로 개발한 초음파 핸드피스 시작품의 성능평가를 통해 골수술용 수술기기로서의 유효성을 확인 하였다. 개발한 골수술용 핸드피스 해석을 위해 본 연구에서는 ANSYS 19.0 ACT Piezo and MEMS Extension 을 활용하여 압전소자(PZT) 기반의 핸드피스 해석을 수행하였다. 최적의 고유진동수 도출을 위해 볼트 조임 란쥬방형 진동자(Bolt-clamped Langevin Type Transducer, BLT)에서 발생하는 초기응력(응력전위)을 고려 하였으며, 볼트 조임값의 변화에 따른 핸드피스의 구동성능을 평가하여 최적의 볼트조임 값을 도출 하였다. 또한 골수술용 초음파 핸드피스의 최적 구동 주파수 대역대로 알려진 20-40 kHz 에서 모달해석(Modal Analysis) 및 주파수 응답(Harmonic Response)을 확인 하였으며 효과적인 골절삭을 위한 Mode(직진선형운동)에서 핸드피스 팁 끝단의 변위를 확인함으로서 최적의 핸드피스의 설계안을 도출 하였다. 최종적으로 제작된 핸드피스는 임피던스 측정 및 변위측정 등의 성능평가를 수행하였으며 해석을 통해 제시된 주파수 대역내 내에서의 유효성 및 안정성을 확인하였다.
황토, 갯벌 및 머드의 중금속 흡착율에 관한 실험적 연구
이인숙(l.S.Lee),이미영(M.Y.Lee),이택중(T.J.Lee),김현정(H.J.Kim),이병창(B.C.Lee),정명상(M.S.Jeong),방은옥(E.O.Bang),송현실(H.S.Song),황혜경(H.K.Hwang),이중호(J.H.Lee),조영채(Y.C.Cho) 대한환경위생공학회 2004 대한환경위생공학회지 Vol.19 No.2
Yellow loess, Tidal plat sediment, and mud are known to be high in adsorption though they have great distinction according to the ratio of clay minerals content and their kinds. Thus one of the samples for this study can be obtained by drying of Yellow loess, Tidal plat sediment, and the mud which is semifinished products that are from the progress of heat treatment and making homogeneity which can be found everywhere in our country. Another sample can be prepared by reducing pollutants with the adsorbent and by burning heavy metals of their own. With the samples, noxious heavy metals such as Pb, Cd, and essential trace elements such as Cu, Fe, Mn by each concentration is tested for adsorption according to pH, the kinds of adsorbents and the amount of injection. With the help of these steps, this study shows that the adsorbents, which are green, reducing the additional pollution and low in price, can be found. It also shows that the optimal condition for removing pollutants can be found and the basic materials for treating water can be offered. The results were as follows;<br/> Yellow loess shows the rates of adsorption by more than 50% and Tidal plat sediment and Mud show it by more than 90%. Thus Tidal plat sediment and Mud are higher than Yellow loess the rates of adsorption.<br/> The pH should be treated in natural condition because the rates of adsorption of Pb, Cd, Cu, Mn excepting Fe in mud is higher in pH 7 than in pH 3 of Yellow loess, Tidal plat sediment, and Mud.<br/> The drying adsorbents are good to use because the rates of adsorption of heavy metals has tendency to be higher in the drying method than in the burning method.<br/> It is considered that the more the amount of the injection of the adsorbent is , the higher the rates of adsorption is, and one gram is reasonable for the amount of the injection of Tidal plat sediment and mud.<br/> Yellow loess is suitable for the treatment of the water that includes low concentration of heavy metals because it has the lower rate of adsorption as the concentration of noxious heavy metals is higher.<br/> It is thought that Tidal plat sediment and Mud is proper for the treatment of the water that includes high concentration of heavy metals because the rates of adsorption has not been changed as the concentration of heavy metals increases.