• Journal of the Korean Society of Visualization
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• v.4 no.2
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• pp.6-10
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• 2006

The functional spherical microcapsules were produced through the innovative conjunction of the well-defined amphiphilic block copolymer and the stable droplet phase flow in the micro chemical plant. The microcapsules were formed to have hollow inner cavity and outer surface wall with nano-pores. To examine the potential of encapsulating foreign biochemical molecules, Congo-red dye was loaded into the microcapsule. The release performance in the specific surroundings such as temperature, pH and time was evaluated quantitatively.

• Journal of Chest Surgery
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• v.26 no.10
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• pp.808-811
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• 1993

Leriche syndrome ia a common entity which causes ischemia of the lower extremities. Since the introduction of aortic resection and homograft replacement by Oudot in 1951, reconstructive procedures to restore distal blood flow by either endarterectomy or, later, with prosthetic graft have become standardized. Recently we experienced a case of Leriche syndrome. A 50 year-old male patient admitted with intermittent claudication, impotence, and symmetrical atrophy at lower extremities. Aortogram revealed complete obstruction at infrarenal abdominal aorta and Doppler sonogram revealed only minimal blood flow at left femoral artery.Successful surgical treatment was accomplished with endarterectomy at proximal left renal artery and a bypass from abdominal aorta at the level of both renal arteries to both external iliac arteries with bifurcated Gore-tex vascular graft. After bypass operation, we did palpate with arterial pulse at both popliteal artery.He was recovered without complication.

• Design & Manufacturing
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• v.2 no.2
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• pp.43-47
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• 2008

This paper is concerned with the analysis of material flow characteristics of stepped rod forming. The analysis in this paper concentrated on the evaluation of the design parameters for deformation patterns of tube forming, load characteristics, extruded length, and die pressure. The design factors such as punch nose radius, die corner radius, friction factor, and punch face angle are involved in the simulation. The stepped rod forming is analyzed by using a commercial finite element code. This simulation makes use of stepped rod material and punch geometry on the basis of punch geometry recommended by International Cold Forging Group. As radius ratio is large, forming load was reduced but extruded length ratio was increased.

• Journal of Magnetics
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• v.11 no.3
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• pp.103-107
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• 2006

In grain oriented electrical steel process, hot band annealing has thought to be essential for obtaining good magnetic properties. New hot rolling method of heavy reduction in early hot rolling stage was applied to obtain good magnetic properties in GO process without hot band annealing. Hot rolling was carried out by varyinghot rolling reduction distribution along hot rolling pass. The heavy hot rolling reduction in rear stand improves the magnetic flux density in the case of no hot band annealing. The hot band specimens of the heavy reduction in front stand shows the elongated hot deformed microstructures in the center layer and strong {001}<110> texture.On the contrary, the heavily reduced specimens in rear stand shows the recrystallization in the center layer of hot band and strong {111}<112> and {110}<001> textures.

• The KSFM Journal of Fluid Machinery
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• v.12 no.4
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• pp.54-62
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• 2009

The feedwater heaters are Critical components in a nuclear power plant. As the operation years of heaters go by, the maintenance costs required for continuous operation increase. When the carbon steel components in nuclear make contact with running fluid, the wall thinning caused by FAC (flow accelerated corrosion) can be generated. Local wall thinning is inevitable at the area around wet steam entrance to be attacked due to the long term operation. Sometimes the shell with thinned wall is eventually ruptured. To identify the relationship between the local wall thinning and fluid behavior of the feedwater heater, the practical data of a plant, which were based on ultrasonic thickness measurement tests, were analyzed and CFD(Computed Fluid Dynamics) analyses were performed.

• Applied Science and Convergence Technology
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• v.26 no.6
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• pp.189-194
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• 2017

Effects of gas injection scheme and rf driving current configuration in a dual turn inductively coupled plasma (ICP) system were analyzed by 3D numerical simulation using CFD-ACE+. Injected gases from a tunable gas nozzle system (TGN) having 12 horizontal and 12 vertical nozzles showed different paths to the pumping surface. The maximum velocity from the nozzle reached Mach 2.2 with 2.2 Pa of Ar. More than half of the injected gases from the right side of the TGN were found to go to the pump without touching the wafer surface by massless particle tracing method. Gases from the vertical nozzle with 45 degree slanted angle soared up to the hottest region beneath the ceramic lid between the inner and the outer rf turn of the antenna. Under reversed driving current configuration, the highest rf power absorption region were separated into the two inner islands and the four peaked donut region.

• Proceedings of the Korea Information Processing Society Conference
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• 2013.05a
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• pp.319-322
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• 2013

본 연구에서는 이동 객체를 컬러기반에서 추적하는데 있어 주변 환경 변화와 추적중인 객체 색상이 유사한 물체가 존재할 경우 보다 안정적으로 추적할 수 있는 방법을 제시한다. 백그라운드 차영상과 모폴로지 연산을 통하여 이동 객체를 검출하고, 매 프레임마다 발생하는 밝기 및 주변 환경의 영향을 고려하여 기존의 CamShift 알고리즘을 보완하였다. 추적 물체와 색상이 비슷한 주변 물체가 존재할 경우 개선된 CamShift는 불안정한 추적을 보여주었는데 이를 해결하기 위해 Optical Flow기반의 KLT 알고리즘과 병합하는 방법을 제시하였다. 실험 결과를 통해 제안된 추적 방법은 기존의 단점을 보완하였으며 추적성능이 개선됨을 확인하였다.

• International Journal of Korean Welding Society
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• v.2 no.1
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• pp.62-66
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• 2002

The Friction Stir Welding (FSW) is a new joining method that was developed at The Welding Institute (TWI) in England in 1991. It applied heating by the rotational friction and material plastic flow. It was developed as a new joining method to solve the problems of epochally in the welding of Al alloys. In the study, 6000series of Alloy composed of Al-Mg-Si, one of the Al alloys that are utilized for shipbuilding and construction, is selected as a specimen and the numerical is executed against the welded zone of FSW. The material used in this study had the unique properties of strength and anti-corrosion, but since the welded joint of this material is easily softened by the welding heat, FSW is executed and the numerical analysis is carried out around the joint. To examine the mechanical behaviors and properties, F.E.M analysis is executed and the developed thermal-elastic-plastic finite analysis are used.

• Journal of the Ergonomics Society of Korea
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• v.32 no.6
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• pp.481-487
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• 2013

Objective: The present study aims to evaluate the visual reactions of users when they are playing games of different flow levels, and to explore the visual variables that can sensitively reflect the different flow levels. Background: The flow is defined as a psychological state where interface users feel their actions in a virtual setting identical to those in real environment. To measure the flow states of users, the questionnaire-based FSS(Flow State Scale) has mostly been used. However, this method is a qualitative test that has limits in terms of the accuracy of users' flow experiences. Therefore, more accurate methods to measure users' flow experiences are required. Method: Ten subjects participated in the experiment, where the independent variables were three games with different flow levels(puzzle games, dot drawing and coloring) and the time frame(the first and last 10 seconds in game playing), whereas the dependent variables included the pupil size and the frequency and duration of eye blinking. This study was a within-subject design. Each participant performed three types of games with different flow levels 3 times for each for 10 minutes, and their visual reactions to each game were measured. Results: The higher the flow cause the bigger pupil size(p<0.01) and the lower eye blinking frequency(p<0.1), indicating that different types of games lead to different flow levels. The pupil size during the last 10 seconds when the flow level was higher was bigger by 2.1% compared with that during the first 10 seconds in game playing(p<0.1), and the eye blinking frequency decreased by 12%(p<0.01). Conclusion: It was found out that the pupil size and the frequency and duration of eye blinking were psychophysiological indices for evaluating users' flow experiences, which could quantify the flow states users go through. The psychophysiological variables capable of measuring diverse aspects of the flow need diversifying to be applicable to precise measurement of the flow. Application: These studies are warranted for both quantitative analysis of flow levels and qualitative improvement of cyber leisure in line with development of healthy games.

• Journal of the Korean Geotechnical Society
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• v.36 no.12
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• pp.17-25
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• 2020

The artificial ground freezing method is a ground amelioration technology that does not have a permanent effect on the ground. One of the key factors that determine the efficiency and design criteria of the artificial ground freezing is the groundwater flow. Therefore, in order to accurately evaluate the behavior of the artificial ground freezing, studies on the effect of water flow on the formation of ice walls must be preceded. In this paper, experimental and numerical analyses were conducted using only pure water to maximize the effect of water flow on the formation of ice walls. A hydro-thermal coupled model for freezing behavior was proposed and the accuracy of the model was verified. Through the numerical and experimental studies, the flow rate dominates not only the formation time but also the shape of the ice wall. In addition, this study proposes a method to indirectly predict the ice wall formation time, which is expected to be highly useful for a practical application where it is difficult to visually identify ice walls.