CFD Study Analysis on the Steam Ejector with Varying Turbulence models

Supriyanto Wibowo,Tony Utomo,HanSik Chung,HyoMin Jeong 대한설비공학회 2008 대한설비공학회 학술발표대회논문집 Vol.2008 No.2

CFD analysis has been carried out in this paper. The purpose is to reveal the understanding of flow phenomena inside the ejector on the performance of steam ejector using three well known turbulence models. In this study, the ejector design was modeled using finite area CFD techniques to resolve the flow dynamics in the ejectors. Furthermore, from this study it can be concluded that by employed vary of turbulence models there are different results in pressure distribution, in contour of Mach number and in Entrainment ratio inside the steam ejector.

Kinetics of lipid raft formation at lipid monolayer-bilayer junction probed by surface plasmon resonance

Ryu, Yong-Sang,Yun, Hansik,Chung, Taerin,Suh, Jeng-Hun,Kim, Sungho,Lee, Kyookeun,Wittenberg, Nathan J.,Oh, Sang-Hyun,Lee, Byoungho,Lee, Sin-Doo Elsevier Applied Science 2019 Biosensors & bioelectronics Vol. No.

<P><B>Abstract</B></P> <P>A label-free, non-dispruptive, and real-time analytical device to monitor the dynamic features of biomolecules and their interactions with neighboring molecules is an essential prerequisite for biochip- and diagonostic assays. To explore one of the central questions on the lipid-lipid interactions in the course of the liquid-ordered (<I>l</I> <SUB> <I>o</I> </SUB>) domain formation, called rafts, we developed a method of reconstituting continuous but spatially heterogeneous lipid membrane platforms with molayer-bilayer juntions (MBJs) that enable to form the <I>l</I> <SUB> <I>o</I> </SUB> domains in a spatiotemporally controlled manner. This allows us to detect the time-lapse dynamics of the lipid-lipid interactions during raft formation and resultant membrane phase changes together with the raft-associated receptor-ligand binding through the surface plasmon resonance (SPR). For cross-validation, using epifluorescence microscopy, we demonstrated the underlying mechanisms for raft formations that the infiltration of cholesterols into the sphingolipid-enriched domains plays a crucial roles in the membrane phase-separation. Our membrane platform, being capable of monitoring dynamic interactions among lipids and performing the systematic optical analysis, will unveil physiological roles of cholesterols in a variety of biological events.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Continuous but spatially heterogeneous membranes were probed by the SPR for monitoring the kinetic behavior of lipid-lipid interactions </LI> <LI> The accompanying biochemical activity of ligand-receptor binding. Our monolayer-bilayer junction methodology of manipulating the bio-membranes enables to precisely control the phase-separation of l<SUB>o</SUB> domains at pre-defined regions on a SPR-based biochip and to unveil the kinetics of the raft formation together with raft-associated receptor-ligand interactions </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>Continuous but spatially heterogeneous membranes were probed by the SPR for monitoring the kinetic behavior of lipid-lipid interactions (a) and the accompanying biochemical activity of ligand-receptor binding. Our monolayer-bilayer junction methodology of manipulating the bio-membranes enables to precisely control the phase-separation of <I>l</I> <SUB> <I>o</I> </SUB> domains at pre-defined regions (b) on a SPR-based biochip and to unveil the kinetics of the raft formation together with raft-associated receptor-ligand interactions (c).</P> <P>[DISPLAY OMISSION]</P>

혼합기 오존 첨가에 따른 가솔린 엔진의 연소특성

이병호(Byongho Lee),이중섭(Chungseub Yi),전유신(Yousin Jun),정한식(Hansik Chung),정효민(Hyomin Jeong) 한국동력기계공학회 2006 한국동력기계공학회 학술대회 논문집 Vol.- No.-

In a conventional and lean operating engine, the state of mixture is very important in the combustion and emission characteristics. Lean operation is known to decrease the formation while maintaining a good fuel economy, but the unstable operation due to misfire and erratic combustion prevents engines from being operated at very lean mixtures, so both combustion rates and exhaust emission formation need to be satisfied comparablely. In this study, it is designed and experimented the modified engine, and analyzed the combustion and exhaust emission according to the change of engine speed and with adding ozone. The conclusions were drawn out and enumerated as a following. 1. At the experimental result of automobile diesel engine, it has been verified that the formation of particulate matter(PM) gas is able to be lower with the addition of optimum quautities of ozone. 2. Carbon monoxide(CO) was formed by the lack of oxygen and the thermal dissociation in the combustion process. Therefore, with the change of swirl valve's position and addition of oxygen and ozone, CO formation was decreased by the increasing of excess O2, and increased by the combustion gas temperature higher. As a result of the two effects, CO formation was decreased in this study. 3. Hydrocarbon(HC) was formed by the lack of 02, and the flow of mixture in cylinder. According to opening of the swirl valve and adding the oxygen and ozone, hydrocarbon gas was decreased by respectively 20%, 9%, and 27.5%. 4. Nitric oxides(NOx) was strongly affected by the combustion gas temperature. As a result of respectively experimental conditions, NOx formation was increased about 20% due to be the higher combustion gas temperature.

선박평형수 처리 시스템 효율 검증을 위한 해양 플랑크톤 생사판별시 Neutral red 염색법 적용 가능성 연구

현봉길,신경순,정한식,최서열,장민철,이우진,최근형,Hyun, Bonggil,Shin, Kyoungsoon,Chung, Hansik,Choi, Seo-Yeol,Jang, Min-Chul,Lee, Woo-Jin,Choi, Keun-Hyung 한국해양학회 2014 바다 Vol.19 No.4

선박평형수를 통한 외래종 확산을 방지하기 위해 국제해사기구(IMO)에서는 2004년 선박평형수관리협약을 채택하였다. 이 협약에 따르면 앞으로 대부분의 선박들은 선박평형수 처리시스템을 통해서 해양 생물을 사멸 또는 제거시킨 후 배출해야 하며, 이는 플랑크톤의 생사판별방법을 통하여 이루어진다. 본 연구에서는 국제적으로 선박평형수 처리후 생사판별법으로 널리 사용되고 있는 fluorescein diacetate assay (FDA) 염색방법의 제한성과 이의 대안으로 Neutral red (NR) 염색방법사용 가능성을 살펴보고자 하였다. FDA 염색법은 대부분의 플랑크톤 염색에 되어서 현재 가장 널리 사용되는 방법임에도 불구하고 본 연구에서는 Ditylum brightwellii 을 제외한 모든 식물플랑크톤 대해서 낮은 염색 효율(전체 평균 염색 효율 <50%)을 보였으며, 식물플랑크톤이 갖는 고유한 형광(적색)에 간섭을 많이 받는 것으로 나타났다. 또한 FDA는 형광파장에 노출된 후 빠르게 색이 바래지는 경향도 관찰되었다. 반면에 NR은 조사된 모든 동 식물플랑크톤 개체수에 대해서 90% 이상의 높은 염색 효율을 보였다. 두 염색법 모두 포르말린을 이용해서 사멸시킨 동 식물플랑크톤에 대해서는 염색이 되지 않았다. 본 연구결과를 통해서 NR 염색법을 이용한 동 식물플랑크톤 생사판별은 매우 효율적이라고 판단된다. In order to prevent the spread of non-indigenous aquatic species through the ballast water in commercial ships, International Maritime Organization (IMO) adopted in 2004 the International Convention for Control and Management of Ship's Ballast Water and Sediments. The Convention mandates treatment of ballast water for most transoceanic voyages and its confirmation of treatment is made with plankton live/dead assay. Fluorescein diacetate assay (FDA), which produces bright green light for live phytoplankton, has been a de facto standard method to determine the survival of marine plankton, but its staining efficacy has been in dispute. In the present study, we examined the limitation of FDA, and compared its efficacy with Neutral red (NR) staining, another promising assay and widely used especially for zooplankton mortality. For all phytoplankton species studied in the present study, except Ditylum brightwellii, the staining efficiency was <50% with FDA. The green FDA fluorescence interfered with phytoplankton autofluorescence in most samples. In contrast, NR assay stained over 90% of both phytoplankton and zooplankton species tested in this study. FDA assay also showed that green FDA fluorescence rapidly faded when phytoplankton cells were exposed to microscope light. Both FDA and NR assay were negative on formalin-killed individuals of both phytoplankton and zooplankton species. Our results suggest that NR assay is more effective for determining the survival of marine plankton and can be applied to test the efficacy of ballast water treatment.