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      • 포스터 전시회 : 단일 액적의 고체 표면 액막과의 충돌 현상에 관한 연구

        고천석 ( C S Ko ),유준호 ( J H Yu ),최낙완 ( N W Choe ),강보선 ( B S Kang ) 한국액체미립화학회 2012 한국액체미립화학회 학술강연회 논문집 Vol.2012 No.-

        In this paper an experimental study is presented to investigate the dynamic behavior of impacting droplet onto a liquid film. The main parameters are the droplet velocity and the thickness of the liquid film. Photographic images are presented to show the formation of crown, central jet and disintegrating droplet from the central jet. The emphasis is on presenting the time evolution of crown diameter, crown height, central jet height and the size of disintegrating droplet from the central jet. The diameter and height of crown are higher for faster droplet and thinner liquid film. On the other hand, the height of central jet are higher for faster droplet and thicker liquid film. The size of disintegrating droplet from the central jet heavily depends on the droplet velocity; Larger droplet is produced with faster falling droplets.

      • KCI등재

        단일 액적의 고체 표면 액막과의 충돌 현상에 관한 연구

        고천석 ( C S Ko ),유준호 ( J H Yu ),최낙완 ( N W Choe ),강보선 ( B S Kang ) 한국분무공학회 2013 한국액체미립화학회지 Vol.18 No.1

        In this paper an experimental study is presented to investigate the dynamic behavior of impacting droplet onto a liquid film. The main parameters are the droplet velocity and the thickness of the liquid film photographic images are presented to show the formation of crown, height, central jet height and the size of disintegrating droplet from the central jct. The diameter and height of crown height of crown are higher for faster droplet and thinner liquid film. On the other hand, the height of cen-tral jet are higher for faster droplet and thicker liquid film. The size of disintegrating droplet from the central jet heavily depends on the droplet velocity; Larger droplet is produced with faster falling droplets.

      • [연료 및 윤활유부문] Demethyl ether와 디젤의 분무 특성 비교

        유준(J.Yu),강진석(J.S. Kang),공장식(J.S. Kong),배충식(C. Bae) 한국자동차공학회 2001 한국자동차공학회 춘 추계 학술대회 논문집 Vol.2001 No.11_1

        Demethyl ether (DME) is one of the most attractive attremative fuels for compression ignition engine. Its main advantage in diesel engine application is high efficiency of diesel cycle with soot free combustion though conventional fuel injection system has 10 be modified due 10 the intrinsic properties of DME. Experimental study of DME and conventional diesel spray employing a conventional fuel injection system with a yea (Valve Covered Orifice) injector was performed al atmospheric conditions. A CCD camera was employed 10 capture time series of spray images followed by spray angles and penetrations of DME were characterised and compared \\ith those of diesel. Increasing rate of the DME injection pressure was lower than that of diesel and residual pressure was higher due 10 high compressibility of DME. Spray angles of DME were generally wider than those of diesel while spray tip penetrations were shorter due 10 higher vapour pressure and faster momentum loss.

      • KCI등재

        Dimethyl Ether와 디젤의 거시적 분무 특성 비교

        유준(J Yu),이주광(J K Lee),배충식(C S Bae) 한국자동차공학회 2002 한국 자동차공학회논문집 Vol.10 No.5

        Dimethyl ether (DME) is one of the most attractive alternative fuel for compression ignition engine. Its main advantage in diesel engine application is high efficiency of diesel cycle with soot free combustion though conventional fuel injection system has to be modified due to the intrinsic properties of DME. Experimental study of DME and conventional diesel spray employing a common-rail type fuel injection system with a 5-holes sac type injector (hole diameter 0.168 mm/hole) was performed in a high pressure chamber pressurized with nitrogen gas. A CCD camera was employed to capture time series of spray images followed by spray cone angles and penetrations of DME were characterized and compared with those of diesel. Under atmospheric pressure condition, regardless of injection pressure, spray cone angles of the DME were wider than those of diesel and penetrations were shorter due to flash boiling effect. Tip of the DME spray was formed in mushroom like shape at atmospheric chamber pressure but it was disappeared in higher chamber pressure. On the contrary, spray characteristics of the DME became similar to that of diesel under 3MPa of chamber pressure. Hole-to-hole variation of the DME spray was lower than that of diesel in both atmospheric and 3MPa chamber pressures. At 25MPa and 40MPa of DME injection pressures, regardless of chamber pressure, intermittent DME spray was observed. It was thought that vapor lock inside the injector was generated under the two injection pressures.<br/> <br/>

      • 커먼레일형 연료분사장치를 이용한 Dimethyl ether의 거시적 분무 특성

        유준(J.Yu),이주광(J.K.Lee),배충식(C.S.Bae) 한국자동차공학회 2002 한국자동차공학회 춘 추계 학술대회 논문집 Vol.2002 No.5_1

        Dimethyl ether(DME) is one of the most attractive alternative fuels for compression ignition engine. Its main advantage in diesel engine application is high efficiency of diesel cycle with soot tree: combustion though conventional fuel injection system bas to be modified due to the intrinsic properties of DME. Experimental study of DME and conventional diesel spray employing a common-rail type fuel injection system with a sac type injector was performed in a high pressure chamber pressurized with nitrogen gas. A CCD camera was employed to capture time series of spray images followed by spray cone angles and penetrations of DME were characterized and compared with those of diesel. Under atmospheric pressure condition, regardless of injection pressure, spray cone angles of the DME were wider than those of diesel and penetrations were shorter due to flash boiling effect. Tip of the DME spray was formed in mushroom like sbape at atmospheric chamber pressure but it was disappeared in higher chamber pressure. On the contrary, spray characteristics of the DME became similar to of diesel under 3MPa of chamber pressure. Hole-to-hole variation of the DME spray was lower than of diesel in both atmospheric and 3MPa chamber pressures. At 25MPa and 40MPa of DME injection pressures, regardless of chamber pressure, intermittent DME spray was observed. It was thought that vapor lock inside the injector was generated under the two injection pressures.

      • 광양만 및 가막만의 유기염소계 화합물 분포에 관한 연구

        김종희(J.H.Kim),조현서(H.S.Cho),유준(J.Yu),최윤석(Y.S.Choi),정창수(C.S.Jung) 한국해양환경·에너지학회 2006 한국해양환경공학회 학술대회논문집 Vol.2006 No.-

        PCBs 및 유기염소계 농약과 같은 유기염소계 화합물은 매우 안정하여 해양환경 중에 유입되면 장기간 잔류하게 된다. 이러한 유기염소계 화합물은 다양한 목적으로 광범위하게 이용되어져 왔으며 극지방 및 대양의 다양한 매질에서도 검출이 되고 있다. 특히 이들 화합물은 소수성으로 해양환경에 유입되면 입자에 흡착하여 퇴적층에 축적되어진다. 본 연구에서는 지형학적으로 반 폐쇄적이며, 주변 공업단지와 농경지에 의해 유기염소계 화합물의 오염 우려지역으로 예상되는 광양만과 가막만을 선정해 표층퇴적물 중 유기염소계 화합물을 조사하석 시ㆍ공간적인 잔류농도 및 분포특성을 파악하였다 광양만과 가막만의 표층퇴적물 중 PCBs 농도범위는 각각 0.18~0.99(평균 0.51±0.06)ng/g dryㆍwt, 0.02~0.70(평균 0.18±0.02)ng/g dryㆍwt.였다. 광양만의 지형학적 구조와 주변 산업 활동에도 불구하고 표층퇴적물의 PCBs 화합물 농도는 국내 주요 산업 항만인 부산, 을산, 영일만에 비해 대체로 낮은 농도 수준이었으며, NOAA의 ER-L보다 낮은 농도분포를 보였다. 광양만의 표층 퇴적물 중 PCBs congeners 분포패턴은 tetra-CB >hepta-CB >tri-CB >penta-CB >nona-CB >deca-CB >hexa-CB 순으로 tetra-CB가 우세하게 나타났다. 광양만은 저염소화 PCBs인 tri-CB, tetra-CB가 높게 나타나 신규 유입이 있을 것으로 사료되어진다. 가막만 표층퇴적물의 PCBs congeners 분포는 penta-CB, hexa-CB, hepta-CB가 검출되었으며 다른 congener는 분포하지 않았다. 광양만과는 상이하게 저염소화 화합물이 존재하지 않아 가막만은 PCBs의 신규 유입은 없는 것으로 나타났다. 광양만 표층퇴적물의 유기염소계 농약인 DDTs와 HCHs의 농도는 각각 ND~0.10(평균 0.06±0.01)ng/g dryㆍwt., ND~0.59(평균 0.24±0.04)ng/g dryㆍwt.로 나타났다. 조사 해역 모두에서 ,p'-DDE가 DDTs 동위체의 대부분을 차지하고 있었으며, HCHs의 경우 γ-HCH가 대부분을 차지하였다. 대부분의 정점에서 ER-L 농도 이하의 값을 보여 광양만 유기염소계 농약의 농도는 우려할 만한 수준은 아니었다. 가막만 표층퇴적물의 유기염소계 농약인 DDTs와 HCHs의 농도는 각각 ND~1.68(평균 0.28±0.06)ng/g dryㆍwt., ND~4.75(평균1.07±0.12)ng/g dryㆍwt.로 나타났다. DDTs의 경우 평균 구성비는 p,'-DDE가 전체 DDT 분해산물 중 76%를 차지하고 있었으며, p,p'-DDD가 17%를 차지하였다. HCHs의 경우 β-HCH와 γ-HCH가 대부분을 차지하고 있었다. 대부분의 정점에서 ER-L 농도 이하의 값을 보여 가막만 유기염소계 농약의 농도는 우려할 만한 수준은 아니었다. Organochlorine compounds such as polychlorinated biphenyls (PCBs) from industrial sources, hexachlorocyclohexanes(HCHs) and DDTs from agricultural activities and their metabolites are ubiquitous, persistent, toxic and bioaccumulative in the marine environment due to their unique chemical properties. There are several input mechanisms that lead to the deposition of organochlorine compounds in the environment. These include urban runoff, municipal sewage, industrial waste, outflow from agricultural area, chemical spill, and atmospheric deposition. In this study five sediments samples were collected from Gwangyang Bay and Camak Bay to survey the spatial distribution pattern of organochlorine compounds in a semi -enclosed bay system Organochlorine compounds in sediments were extracted using dichloromethane and purified using florisil column. Individual compounds were detected using a gas chromatography/ electron capture detector(GC/ECD) for quantification. The concentrations of PCBs in sediments from Gwangyang Bay and Gamak Bay ranged from 0.18 to 0.99ng/g dryㆍwt., and from 0.02 to 0.70ng/g dryㆍwt., respectively. The concentrations of PCBs appeared to be higher than the sites of active industrial activities. Mean concentrations of PCBs in sediments were less than Effect Range Low(ER-L) values suggested by NOAA in US. The concentration of DDTs in sediments from Gwangyang Bay and Gamak Bay ranged from ND to 0.10ng/g dryㆍwt., and from ND to 1.68ng/g dryㆍwt., respectively. p,p'-DDE appeared to be the dominant isomer among DDT isomers in sediments from Gwangyang Bay. The percentage composition of p,p'-DDE and p,p'-DDD concentration in Gamak Bay were 76%, 17%, respectively. Mean concentrations of DDTs in this study were less than Effect Range Low(ER-L) values suggested by NOAA in US. The concentrations of HCHs in sediments from Gwangyang Bay and Gamak Bay ranged from ND to 0.59ng/g dryㆍwt., and from ND to 4.75ng/g dryㆍwt., respectively. γ-HCH were the major components of HCH compounds in Gwangyang Bay. The concentrations of PCBs in this study are lower concentration range than Daya Bay, Osaka Bay and Bohai sea. In addition, concentrations of PCBs in this study are below ER-L value.

      • 초음파를 이용한 오염퇴적물 정화

        이용화(Y.H. Lee),김정배(J.B. Kim),유준(J. Yu),권기영(K.Y. Kwon),박중현(J.H. Park) 한국해양환경·에너지학회 2004 한국해양환경공학회 학술대회논문집 Vol.2004 No.-

        퇴적물 오염이 심화된 연안수역에서는 오염에 민감한 생물종들이 사라질 수 있으며, 수생 생물의 건강도에도 나쁜 영향을 미친다. 그러므로 연안 오염퇴적물을 준설하여 해양투기를 하는 것이 일반적이다. 그러나 준설물을 해양 투기할 경우 또 다른 수질오염을 야기할 수 있기 때문에 국제적으로 action level을 제정하는 등 해양투기가 보다 엄격하게 제한될 것이기 때문에 오염된 퇴적물의 처리에 관한 기술개발이 필요하다. 토양세척은 토양에 흡착된 오염물을 토양으로부터 분리하거나, 오염이 심한 silt와 clay등 작은 입자들을 오염이 덜한 모래 등 입자가 큰 입자와 분리하는 기작을 이용하는 것으로 그 주된 unit가 scrubbing unit다. 본 연구에서는 scrubbing unit의 세척보조제 대신 초음파를 사용함으로서 오염된 퇴적물을 정화하고자 하였다. 그 결과 퇴적물 중 유기물을 최고 40% 정도 처리할 수 있는 것으로 나타났다.

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