• Transactions of the Korean Society of Mechanical Engineers B
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• v.28 no.8 s.227
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• pp.961-967
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• 2004

An inclined jet impinging on a pin fin heat sink is proposed and investigated experimentally. To investigate the flow pattern, flow visualization using fluorescence and velocity measurement using particle image velocimetry(PIV) are conducted with water. The jet impinges over a wide span of the heat sink with a large recirculation in the upper free space and occasionally with another smaller one in the upstream corner. Further, thermal experimentation is conducted using air to obtain temperature profiles using a thermocouple rake in the air and using thermal image on the heat sink back plate, with impinging angles of 35, 45 and 55 degrees. The Reynolds number range based on the nozzle slot is varied from 1507 to 6405. The results show that impinging angle of 55 degree shows the largest heat transfer capability. The results of thermal experiment are compared and discussed with those of flow visualization.

• Journal of Advanced Marine Engineering and Technology
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• v.26 no.4
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• pp.472-484
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• 2002

To analyze the characteristics of air flow and $CO_2$ extinguishant transfer when extinguishant is injected into a closed space similar to marine engine room, a numerical simulation on a space was performed. Flow fields and $CO_2$ concentration fields are calculated according with the variation of the location & injection angle of nozzles. The results of simulation showed that the pattern of recirculation flow was affected greatly with the location & injection angle of nozzles and such a recirculation flow accelerated mass transfer of $CO_2$ and greatly affected the diffusion process of $CO_2$ extinguishant. It is considered that this result of this study can be useful to designing the arrangement of nozzles for the $CO_2$ fire fighting equipments in a marine engine room.

• Proceedings of the Korean Information Science Society Conference
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• 2010.11a
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• pp.21-22
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• 2010

Brain-Computer Interface (BCI) 는 뇌 신호를 이용하여 생각으로 기계 및 컴퓨터를 제어 할 수 있는 기술이다. 뇌전도(Electroencephalography, EEG) 를 이용한 본 연구는 왼쪽/오른쪽 손 상상 움직임 실험에 대해서 특징 추출 (feature extraction)에 관�� 연구로 총 9명의 피험자로부터 얻어진 뇌 전도 데이터를 이용하여 전통적인 방법 (Common Spatial Pattern, CSP 및 Fisher Linear Discriminant, FLDA)을 이용해 구한 분류 정확도와 본 논문에서 사용 된 Symbolic transfer entropy (STE)을 통해 얻어진 특징에 대한 결과를 보여 준다. 본 연구를 통하여 STE를 통한 특징 추출 방법이 의미가 있다고 생각한다.

• The Korean Journal of Applied Statistics
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• v.15 no.2
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• pp.311-321
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• 2002

Transfer function model(TFM) capturings conditional heteroscedastic pattern is introduced to analyze stochastic regression relationship between the two time series. Nonlinear ARCH concept is incorporated into the TFM via threshold ARCH and beta- ARCH models. Steps for statistical analysis of the proposed model are explained along the lines of the Box & Jenkins(1976, ch. 10). For illustration, dynamic analysis between KOSPI and NASDAQ is conducted from which it is seen that threshold ARCH performs the best.

• Steel and Composite Structures
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• v.24 no.3
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• pp.359-367
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• 2017

In this work, transient heat transfer analysis of functionally graded (FG) carbon nanotube reinforced nanocomposite (CNTRC) cylinders with various essential and natural boundary conditions is investigated by a mesh-free method. The cylinders are subjected to thermal flux, convection environments and constant temperature faces. The material properties of the nanocomposite are estimated by an extended micro mechanical model in volume fraction form. The distribution of carbon nanotube (CNT) has a linear variation along the radial direction of axisymmetric cylinder. In the mesh-free analysis, moving least squares shape functions are used for approximation of temperature field in the weak form of heat transform equation and the transformation method is used for the imposition of essential boundary conditions. Newmark method is applied for solution time depended problem. The effects of CNT distribution pattern and volume fraction, cylinder thickness and boundary conditions are investigated on the transient temperature field of the nanocomposite cylinders.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.3 no.5
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• pp.365-375
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• 1991

Confined natural convection due to lateral temperature difference in rectangular enclosures was studied numerically and experimentally for the insulated and the constant temperature enclosures. In the case of insulated enclosure, the flow pattern and heat transfer modes are rather simple depending mainly upon Rayleigh number. In the case of isothermal enclosure, however, the phenomena of flow and heat transfer are somewhat complex and interesting due to the stable thermal gradients and various circumstances resulted from four wall temperature conditions. As a dimensionless variable, to describe properly the flow and heat transfer phenomena in the isothermal enclosure, temperature difference ratio ${\Delta}T_v/{\Delta}T_H$ is newly introduced and this parameter seems to be appropriate in the analysis of results on the effect of stabilizing thermal gradient.

• Journal of Aquaculture
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• v.12 no.4
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• pp.275-281
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• 1999

The utility of RSV-LTR and carp beta-actin promoters was evaluated in a marine flatfish species, Limanda Yokohamae by examining successful expression of transgenic DNA in muscles (transfected by direct injection) and in early embryos (transformed by lipofected sperm). The expressed pattern of injected DNA in skeletal muscles was dependent on the DNA amount injected. The activity reached to maximal level at 48 hours post injection, and persisted up ot 1 month transiently. Gene transfer into early embryo of this species was successfully achieved using lipofected sperm with the efficiency ranging 36.8% to 48.1%. The expression of transgene during embryonic development was shown as stage-specific and transient.

• Journal of the Korean Society of Visualization
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• v.2 no.2
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• pp.66-72
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• 2004

The heat transfer and pressure drop characteristics of $CO_{2}$ are substantially different from those for CFC and HCFC refrigerants. In addition, geometric effects on two-phase flow patterns of $CO_{2}$ are also very significant in many respects. Therefore, two-phase flow patterns of $CO_{2}$ in a narrow rectangular channel or a small diameter tube whose gap size or hydraulic diameter is less than 2 mm are very important to understand heat transfer characteristics and to develop an appropriate heat transfer correlation. In the present study, the evaporation process of $CO_{2}$ in a narrow rectangular channel is visualized at various test conditions, and then the effects of operating conditions are analyzed.

• 한국전산유체공학회:학술대회논문집
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• 2011.05a
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• pp.129-134
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• 2011

In this paper, the confined single slot jet impingement is investigated numerically. Although the geometry of the jet impingement is simple, the flow pattern of the jet impingement is complex and the numerical results of the jet impingement is affected much by numerical methods. The first goal of this study is to analyze the effects of Reynolds models and numerical spatial discretization schemes on the results of heat transfer performance and the flaw characteristics and to select the best method. Various versions of the low Reynolds number k-epsilon turbulence models are compared. Using the selected numerical method, the flow field and heat transfer characteristics of confined single slot jet impingement on a moving plate are analyzed.

• Proceedings of the Korean Society of Embryo Transfer Conference
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• 2006.10a
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• pp.57-57
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• 2006