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진공성형을 이용한 삼엽식 고분자 심장판막의 제작과 혈류역학적 성능평가
김경현,황창모,정기석,안치범,김범수,이정주,남경원,선경,Kim, K.H.,Hwang, C.M.,Jeong, G.S.,Ahn, C.B.,Kim, B.S.,Lee, J.J.,Nam, K.W.,Sun, K. 대한의용생체공학회 2006 의공학회지 Vol.27 No.6
In the artificial heart application, productivity and hemodynamic properties of artificial heart valves are crucial in successiful application to long term in vivo trials. This paper is about manufacture and assessment of trileaflet polymer heart valves using vacuum forming process(VFP). The VFP has many advantages such as reduced fabrication time, reproducibility due to relatively easy and simple process for manufacturing. Prior to VFP of trileaflet polymer heart valves, polyurethane(Pellethane 2363 80AE, Dow Chemical) sheet was prepared by extrusion. The sheets were heated and formed to mold shape by vacuum pressure. The vacuum formed trileaflet polymer heart valves fabrication is composed of two step method, first, leaflet forming and second, conduit forming. This two-step forming process made the leaflet-conduit bonding stable with any organic solvents. Hydrodynamic properties and hemocompatibility of the vacuum formed trileaflet polymer heart valves was compared with sorin bicarbon bileaflet heart valve. The percent effective orifice area of vacuum formed trileaflet polymer heart valves was inferior to bileaflet heart valve, but the increase of plasma free hemoglobin level which reflect blood damage was superior in vacuum formed trileaflet polymer heart valves Vacuum formed trileaflet polymer heart valves has high productivity, and superior hemodynamic property than bileaflet heart valves. Low manufacturing cost and blood compatible trileaflet polymer heart valves shows the advantages of vacuum forming process, and these results give feasibility in in vivo animal trials in near future, and the clinical artificial heart development program.
헬름홀츠 공진기에 의한 유사 흡기시스템의 비정상유동 특성
김경현(K. H. Kim),강희영(H. Y. Kang),강경은(K. Y. Kang),고대권(D. K. Koh),안수길(S. K. Ahn) 한국동력기계공학회 2007 한국동력기계공학회 학술대회 논문집 Vol.- No.-
Unsteady flows in a semi-induction system was investigated to verify their characteristics. Inside of the induction system in a diesel engine, wave is generated and it affects significantly to breathing performance. The system consists of rotary valve, intake pipe and resonator. To make a air pulsation, a rotary valve was contrived and employed in this system. And also, A side-branched Helmholtz resonator is mounted in the intake pipe to enhance a breathing capacity. The phase and amplitude of the pulsating flow in an unsteady flow system were found to be the strong factor that could be significantly affects to charging capacity. Some of the results given from experiment are described.
김경현(K. H. Kim),김종환(J. H. Kim),강희영(H. Y. Kang),고대권(D. K. Koh) 한국동력기계공학회 2007 한국동력기계공학회 학술대회 논문집 Vol.- No.-
Internal combustion engineers commonly use computer programs to simulate the gas dynamics of an engine manifold. Since these programs are typically one-dimensional model, flow characteristics within the manifold junctions cannot be accurately represented using one-dimensional approach, as the fluid flow in the vicinity of such area is being multi-dimension. Therefore, using a pressure loss junction model to represent such a multi-dimensional flow, enables us to express a complex junctions as one-dimensional, when we treat it as a special boundary. This paper represents some results of investigation for the pressure-loss coefficient using real size Tr-type junction that can be used in a product vehicle.
연료 분사시기가 전자제어 디젤엔진의 엔진 성능 및 배기 배출물에 미치는 영향
김경현(K. H. Kim),김주신(J. S. Kim),이한성(H. S. Lee),강희영(H. Y. Kang),고대권(D. K. Koh) 한국동력기계공학회 2009 한국동력기계공학회 학술대회 논문집 Vol.2009 No.11
This paper describes the engine performance and exhaust emissions of a direct injection diesel engine, operating electronically controlled diesel fuel injector with variable injection timing. Fuel injection was controlled to retard or advance initiation of the injection event by electronically controlled fuel injection unit injector. When fuel is injected into cylinders of a DI diesel engine it will go through ignition delay of processes before being exhausted to the outside. Injection timing of DI diesel engine has a significant effect upon performance and emission
김경현(K.H. KIM),강병희(B.H. Kang),전윤석(Y.S. Jun),목형수(H.S. Mok),최규하(G.H. Dhoe) 전력전자학회 2002 전력전자학술대회 논문집 Vol.- No.-
Recently, there are many researches in several places for a new resource, ahead. Also, Water of 70% m the earth it is interested and studied by around world. Long ago, in the side processing-use, it is making study the welding of Hydrogen-oxygen Gas, which is burned to acquired It( hydrogen + oxygen) by electric-disintegration into water, which has perfect-burning rather than exhaust carbon and It has excellent-sides in financials and efficiencies than existing-gas welding by sparking-characteristics of Hydrogen Oxygen gas. Therefore, with constant current source, It is intended to make a producing gas ratio through designing and making for the use of SCR rectifier of existing-formula and then m this paper it hopefully is coming up to characteristics of welding machine and producer of hydrogen oxygen gas with current-controlled type.