• Journal of Advanced Marine Engineering and Technology
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• 제24권3호
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• pp.79-87
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• 2000

This paper describes experimental investigations of helium-air exchange flow through openings with vertical partitions. Such exchange flows may occur following rupture accident of stand pipe in high temperature gas cooled reactor. Exchange flow rates are investigated experimentally by using partitioned opening and opening with extended partition to assess fluids interference of the exchange flow at the stand pipe rupture accident. A tests vessel with the two types of opening on top of test cylinder is used in the experiments. An estimation method of mass increment is developed and applied to measure the exchange flow rate. A technique of flow visualization by Mach-Zehnder interferometer is provided to recognize the exchange flows. Amplitude and progress of interference fringes of the flows are observed and used as a support in comparison with the exchange flow rates. Flow passages of upward flow of the helium and downward flow of the air for both two types of the opening are separated by inserted partition within the opening, but in the case of partitioned opening, unseparated flow is formed at the opening entrance and the two flows interface. The exchange flow rate for the partitioned opening is not greater than that of the opening with extended partition because of the fluids interference at the entrance of opening. Finally, the fluids interference at the opening entrance is found to be one of important factors on the helium-air exchange flow rate.

• 한국전자통신학회논문지
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• 제3권4호
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• pp.313-318
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• 2008

차세대 Web 2.0 시대의 사용자들은 UI에 대한 시각적, 감성적 요소를 충족시키고 각종 정보에 대해 즉각적인 인식이 가능한 화면을 요구하고 있다. 이러한 사용자의 요구에 능동적으로 대처하기 위해서는 개발자와 디자이너의 상호 협력이 더욱 절실해져가고 있다. 이에 마이크로소프트사는 웹 프레젠테이션 작성 시 다양한 플랫폼에 풍부한 기능과 시각적으로 뛰어난 웹페이지를 개발할 수 있는 Silverlight를 출시하였다. 디자이너와 개발자의 협업이 가능하고 여러 개발 툴에 접근이 가능한 Silverlight를 활용하여 기존의 창 개념에 투명도와 애니매이션을 적용하고 3D 효과를 제공함으로써 시각적인 효과를 높인 창고관리시스템을 구현하였다.

• BMB Reports
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• 제46권8호
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• pp.416-421
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• 2013

Genome-wide association studies (GWAS) have become popular as an approach for the identification of large numbers of phenotype-associated variants. However, differences in genetic architecture and environmental factors mean that the effect of variants can vary across populations. Understanding population genetic diversity is valuable for the investigation of possible population specific and independent effects of variants. EvoSNP-DB aims to provide information regarding genetic diversity among East Asian populations, including Chinese, Japanese, and Korean. Non-redundant SNPs (1.6 million) were genotyped in 54 Korean trios (162 samples) and were compared with 4 million SNPs from HapMap phase II populations. EvoSNP-DB provides two user interfaces for data query and visualization, and integrates scores of genetic diversity (Fst and VarLD) at the level of SNPs, genes, and chromosome regions. EvoSNP-DB is a web-based application that allows users to navigate and visualize measurements of population genetic differences in an interactive manner, and is available online at [http://biomi.cdc.go.kr/EvoSNP/].

• Reproductive and Developmental Biology
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• 제28권4호
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• pp.257-260
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• 2004

Efficiency of somatic cell nuclear transfer was investigated in mice. First, oocyte activation was induced by SrCl₂, and the rate of development was compared with embryos from normal fertilization. Although more than one half of SrCl₂-treated oocytes developed to blastocysts (146/262, 55.7%), the rate of blastocyst formation was significantly lower than normal fertilization controls (59/79, 74.6%). Second, enucleation of oocytes was performed using Polscope that enables non-invasive visualization of metaphase spindles. Such approach could not only avoid damage of oocytes during an exposure to UV light often employed in conventional enucleation procedures, but could also assure the removal of nuclei from all oocytes operated because of monitoring the location of spindles during an entire process of enucleation. Morphologically normal blastocysts were obtained from the transfer of cumulus cell nuclei into enucleated oocytes. However, the rate of development into the blastocyst stage was still low (4/93, 4.3%). This reflects that the nuclear transfer procedure used in this study was not sufficiently optimized, and other factors may also impact greatly the efficiency of nuclear transfer. Including an induction of oocyte activation and method of enucleation tested in this study, a lot more elements are remained to be optimized to improve the efficiency of somatic cell nuclear transfer in mice.

• International Journal of Naval Architecture and Ocean Engineering
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• 제2권2호
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• pp.112-118
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• 2010

The numerical study about the vortex-induced vibration and vortex shedding in the wake has been presented. Prior to the numerical simulation of flexible riser systems concerning engineering conditions, efficiency validating of the proposed FSI solution method have been performed. The comparison between numerical simulation and published experimental data shows that the CFD method designed for FSI solution could give acceptable result for the VIV prediction of flexible riser/pipe system. As meaningful study on VIV and vortex shedding mode with the focus on flexible riser model systems, two kinds of typical simulation cases have been carried out. One was related to the simulation of vortex visualization in the wake for a riser model subject to forced oscillation, and another was related to the simulation of fluid-structure interaction between the pipes of coupled multi-assembled riser system. The result from forced oscillation simulation shows that the vortex-induced vibration with high response frequency but small instantaneous vibration amplitude contributes to vortex conformation as much as the forced oscillation with large normalized amplitude does, when the frequency of forced oscillation was relatively high. In the multi-assembled riser systems, it has been found that the external current velocity and the distance between two pipes are the critical factors to determine the vibration state and the steady vibration state emerging in quad-pipe system may be destroyed more easily than dual-pipe system.

• 설비공학논문집
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• 제15권10호
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• pp.809-820
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• 2003

The present study investigates effects of flow velocity on the convective heat/mass transfer characteristics in wavy ducts of a primary surface heat exchanger application. Local heat/mass transfer coefficients on the wavy duct sidewall are determined by using a naphthalene sublimation technique. The flow visualization technique is used to understand the overall flow structures inside the duct. The aspect ratio and corrugation angle of the wavy duct is fixed at 7.3 and 145$^{\circ}$ respectively, and the Reynolds numbers, based on the duct hydraulic diameter, vary from 100 to 5,000. The results show that there exist complex secondary flows and transfer processes resulting in non-uniform distributions of the heat/mass transfer coefficients on the duct side walls. At low Re (Re<1000), relatively high heat/mass transfer regions like cell shape appear on both pressure and suction side wall due to the secondary vortex flows called Taylor-Gortler vortices perpendicular to the main flow direction. However, at high Re (Re>1000), these secondary flow cells disappear and boundary layer type flow characteristics are observed on pressure side wall and high heat/mass transfer region by the flow reattachment appears on the suction side wall. The average heat/mass transfer coefficients are higher than those of the smooth circular duct due to the secondary flows inside wavy duct. And also friction factors are about two times greater than those of the smooth circular duct.

• 한국컴퓨터그래픽스학회논문지
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• 제22권5호
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• pp.49-56
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• 2016

Oculus Rift, HTC Vive 등의 PC기반 Virtual Reality Head Mount Display 뿐 아니라, Google Cardboard, Samsung Gear VR등과 같은 모바일 VR HMD들이 출시 되고 있다. 그런데 HMD는 착용 시 사용자의 외부시야를 가리게 되므로 VR을 체험하는 공간의 실제 환경에 존재하는 각종 가구에 걸려 넘어지거나 벽 등의 위험요소들에 의해 사용자가 부딪혀 다치고 또는 가구 등이 파손 되는 상황이 일어날 수 있지만 아직 이것에 대해서 확실한 방안이 연구되어 있지 않은 상태이다. 본 논문에서는 Microsoft Kinect V1를 이용하여 사용자가 움직일 공간을 미리 3d Scanning하고 Minimap 방식으로 Scanning한 장애물의 위치 및 정보를 몰입감을 덜 저하시키면서 시각화하여 사용자에게 알려줌으로써 부상위험을 줄이는 방법으로 VR의 대중화를 돕는 방안을 제시 한다.

• 한국추진공학회지
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• 제13권4호
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• pp.9-15
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• 2009

스크램제트 엔진의 연소기 내부 유동은 초음속이므로 유동의 잔류시간과 혼합율의 증대가 효과적인 연소를 가능하게 하는 주요 요인으로 작용한다. 본 연구에서는 연료-공기 혼합기로써 L/D=4.8인 개방형 공동 모델을 사용하였고, 공동 앞에서의 경사 연료 분사 시 분사구 주위와 공동 주위의 유동특성을 살펴보기 위하여 레이저 슐리렌 기법과 압력측정을 실시하였다. 측정에 사용된 레이저 슐리렌은 10 ns의 매우 짧은 광원 지속시간을 보유하여 공동부근의 비정상 유동 현상을 효과적으로 관찰할 수 있었다. 압력측정은 연료 분사비 J(운동량비)를 변화시켜 가며 측정하였으며, 운동량비에 따른 연소기 내부 주요 압력상승 지점의 변화를 살펴 볼 수 있었다.

• 대한기계학회논문집B
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• 제28권11호
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• pp.1459-1466
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• 2004

The purpose of this study is to investigate the effect of swirler angle and the aspect ratio of swirl chamber of nozzle on the characteristics of single and twin spray. The characteristics of sprays have been investigated by measuring the spray angle, droplet size and velocity. Visualization of spray was conducted to obtain the spray angle and breakup process. The spray characteristics such as droplet size and velocity were measured by Phase Doppler Anemometry(PDA). It was found that the spray angle was increased with increasing the swirler angle. For both sprays, the axial velocity and SMD were decreased with increasing the swirler angle. It was also shown that the axial velocity and SMD were decreased with increasing the aspect ratio of swirl chamber, but for the twin spray, the axial velocity and SMD were not influenced significantly by the changing the aspect ratio of swirl chamber. The effect of swirler angle on the spray characteristics was greater than the aspect ratio of swirl chamber for single spray. The nozzle pitch was one of the important factors affecting the spray characteristics of twin spray.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2002년도 봄 학술발표회 논문집
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• pp.445-452
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• 2002

In the field of civil and geotechnical engineering, students conduct a variety of soil tests to fulfill undergraduate soil mechanics course requirement. There is a range of problems in soil laboratory instruction, such as, some students not getting hands on experience of conducting tests because of inadequate number of apparatus, time constraints and inability in exciting students to seriously conduit the experiments, However when these laboratory soil tests are simulated with multimedia interaction ann visualization techniques, the students conceptual understanding of soil mechanics is enhanced. The simulation program for website teaching is a computer based instructional package intended to complement, and potentially replace, some physical testing in a real soil laboratory. The overall aim of this project is to develop an experimental simulation program toward active learning and development of critical thinking skills, including data interpretation, understanding of the precesses and influential factors, and problem solving. Therefore enable students to access website to team experimental procedure at any time or place.