• 한국가시화정보학회지
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• 제19권1호
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• pp.43-49
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• 2021

In this experimental study, measurement techniques such as backlight imaging, optical patternator, and laser sheet drop sizing were applied to characterize open-type swirl injector used in Russian liquid rocket engine, RD 107. The typical development of swirl spray was observed in backlight images. The breakup length was measured by using the ratio between Mie scattering and fluorescence signal. Relative Sauter Mean Diameter was measured by using laser sheet drop sizing and the possible source of errors were discussed.

• 대한기계학회논문집A
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• 제21권3호
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• pp.457-469
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• 1997

A nuclear spent fuel shipping cask is required by IAEA and domestic regulations to withstand a 9m free drop condition. In this paper, the structural analysis under the 9m side drop condition was performed to understand the dynamic impact behavior and to evaluate the safety of the cask for 7 PWR nuclear spent fuel assemblies. The analysis result was compared with the measured value of the 9m side drop test for the 1/3 scaled-down model and the accuracy of the 3D analysis was confirmed. Analysis in accordance with the diameter of impact limiters for the proto-type cask were performed. Through the analysis, the impact behaviors due to the side drop and the effects dependent on the diameter of impact limiters were grasped. Maximum stress intensities on each part of the cask were respectively calculated by using the stress evaluation program and the structural safety of the cask was finally evaluated in accordance with the regulations.

• 한국농공학회논문집
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• 제54권2호
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• pp.55-65
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• 2012

In the winter season, when the ventilation system is operating, the fresh cold air from the slot-type openings of broiler house which directly reached the animal zone can cause various problems such as thermal stress, decreasing of feed and water consumption, occurrence of respiratory disease, and etc. Therefore it is very important to control the trajectory of aero-flow from the slot openings to induce an efficient thermal heat change. Jet-drop distance model was proposed to predict and control the jet-trajectory. However their study was restricted due to the small scaled model and difficulties of measuring the Jet-drop distance. In this study, CFD was applied to analyze qualitatively and quantitatively the jet-drop distance in a real broiler house. The various variables were considered such as installed slot-angle, designed ventilation rate, and the outdoor ambient temperature. From the present study, two linear-regression models using the Jet-drop factor and corrected Archimedes number, and their R-squared values 0.744 and 0.736, respectively, were used. From this study, the applicability of CFD on the analysis of Jet-drop distance model was confirmed.

• Nuclear Engineering and Technology
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• 제46권4호
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• pp.529-540
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• 2014

In this research, a drop impact analysis of a fuel assembly in a research reactor is carried out to determine whether the fuel plate integrity is maintained in a drop accident. A fuel assembly drop accident is classified based on where the accident occurs, i.e., inside or outside the reactor, since each occasion results in a different impact load on the fuel assembly. An analysis procedure suitable for each drop situation is systematically established. For an accident occurring outside the reactor, the direct impact of a fuel assembly on the pool bottom is analyzed using implicit and explicit approaches. The effects of the key parameters, such as the impact velocity and structural damping ratios, are also studied. For an accident occurring inside the reactor, the falling fuel assembly may first hit the fixing bar at the upper part of the standing fuel assembly. To confirm the fuel plate integrity, a fracture of the fixing bar should be investigated, since the fixing bar plays a role in protecting the fuel plate from the external impact force. Through such an analysis, the suitability of an impact analysis procedure associated with the drop situation in the research reactor is shown.

• 패션비즈니스
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• 제12권5호
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• pp.24-38
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• 2008

As an attempt to improve the seaming of clothes exported to China, this study is intended to strengthen the clothing industry in Korea by providing data on the body figures of Chinese women. Direct measurement was conducted on 193 women aged 19-24 residing in Shanghai, China. Then we classified and identified the body types and characteristics of Chinese women based on the drop values suggested by the National Standard of the People's Republic of China(GB/T 1335.2-1997). The following is a summary and conclusion of this study. 1. The following results were obtained by measuring the body sizes of women aged 19-24 living in Shanghai, China. 2. After having conducted a factor analysis on 111 body measurement items, 15 index items, and 11 calculation items, we were able to deduce a total of 6 factors. 3. We categorized the body types of 19-24 year-old women living in Shanghai, China according to the drop values suggested by GB/T 1335.2-1997 where D-type was added to Y, A, B, and C-types for a total of 5 categories. The characteristics of each body type following the body type structure factor are Y-type for slender type, A-type for standard type, B-type for slightly large type, and C-type for obese type.

• 대한조선학회논문집
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• 제45권6호
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• pp.735-749
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• 2008

For the development of the original technique of structural safety assessment of Cargo Containment System(CCS) in membrane type LNG carriers, it is necessary to understand the characteristics of dynamic response behavior of CCS structure under sloshing impact pressure. In the previous study, the wet drop impact response analyses of CCS structure in membrane Mark III type LNG carriers were carried out by using Fluid-Structure Interaction(FSI) analysis technique of LS-DYNA code, and were also validated through a series of wet drop experiments for the enhancement of more accurate shock response analysis technique. In this study, the characteristics of structural shock response behaviors of CCS structure were sufficiently figured out by careful examinations of the effects of specimen weight, drop height, incident angle, corrugation and stiffness of inner hull on its shock response behaviors. The shock response analysis of upward shooting fluid to inner hull was performed, and the reason of faster strain response than shock pressure one was also figured out.

• 전기전자학회논문지
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• 제21권1호
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• pp.73-76
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• 2017

실리콘카바이드 소자는 넓은 밴드갭을 갖는 물질로서 많은 주목을 받아왔다. 특히 4H-SiC 쇼트키 배리어 다이오드는 빠른 스위칭 속도와 낮은 순방향 전압강하의 특성으로 인해 널리 사용되고 있다. 그러나 쇼트키 배리어 다이오드의 낮은 신뢰성으로 인한 문제로 대안인 Super Barrier Rectifier(SBR)가 연구되었다. 본 논문은 4H-SiC trench-type accumulation super barrier rectifier(TASBR)를 분석하고 제안한다. 2D 시뮬레이션을 통해 본 구조는 심각한 역방향 저지전압의 감소와 누설전류의 증가가 없는 동시에 순방향 전압 강하는 21.06% 향상됨을 확인 할 수 있었다. 이러한 새로운 정류기 구조를 이용하면 전력손실이 적은 애플리케이션을 기대할 수 있다.

• 대한기계학회논문집B
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• 제32권9호
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• pp.676-682
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• 2008

Numerical analysis was carried out to examine the heat transfer and pressure drop characteristics of plate heat exchangers for absorption application using Computational Fluid Dynamics(CFD) technique. A commercial CFD software package, FLUENT was used to predict the characteristics of heat transfer, pressure drop and flow distribution within plate heat exchangers. In this paper, a welded plate heat exchanger with the plate of chevron embossing type was numerically analyzed by controlling mass flow rate, solution concentration, and inlet temperatures. The working fluid is $H_2O$/LiBr solution with the LiBr concentration of 50-60% in mass. The numerical simulation shows reasonably good agreement with the experimental results. Also, the numerical results show that plate of the chevron shape gives better results than plate of the elliptical shape from the view points of heat transfer and pressure drop. These results provide a guideline to apply the welded PHE for the solution heat exchanger of absorption systems.

• Journal of Advanced Marine Engineering and Technology
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• 제39권4호
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• pp.443-448
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• 2015

선박용 질소산화물 저감장치의 혼합영역에서 유동혼합 성능을 개선하기 위해 스월형 혼합기가 개발되었다. 본 연구에서는 스월형 혼합기와 각단의 날개 각도가 조절 가능한 다단 스월형 혼합기가 고려되었다. 두 스월형 혼합기의 최적 날개 각도를 도출하기 위해 날개 각도가 균일지수 및 압력강하에 미치는 영향을 수치해석 기법을 이용하여 조사하였다. 스월형 혼합기에서는 혼합기의 날개 각도를 $10^{\circ}$ 에서 $80^{\circ}$ 까지 변화시킬 때, 최적의 유동혼합 성능은 베인 각도 $30^{\circ}$에서 $60^{\circ}$ 범위에서 나타났으나, 압력강하는 베인 각도 증가에 따라 선형적으로 증가하였다. 반면 다단 스월형 혼합기에서는 각 단의 날개각도를 조절함으로써 압력강하를 낮추면서도 높은 혼합성능의 유지가 가능함을 보였다.

• Korean Chemical Engineering Research
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• 제53권1호
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• pp.16-21
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• 2015

다이어프램 방식 준비작동식 유수검지장치의 압력손실을 줄이기 위하여 본체 구조를 개선하였다. 개정된 유수제어밸브의 압력손실시험 기술기준을 통과하기 위해서는 압력손실이 20.7 kPa을 초과하여서는 안된다. 압력손실시험은 한국소방산업기술원 유수제어밸브 기술기준에 따라서 실시하였다. 준비작동식 유수검지장치는 습식 유수검지장치에 비해 압력손실이 크게 발생하였는데, 그 원인을 유체의 유동현상과 관련하여 분석하였다. 준비작동식 유수검지장치의 본체 내부 구조는 유로의 단면 크기와 방향 변화로 인해 압력손실 요인이 많았다. 이러한 압력손실 요소를 제거하기 위해 습식 유수검지장치와 비슷한 클래퍼 타입으로 구조를 변경하였다. 구조 변경 후 압력손실 값은 호칭 80A인 경우 80.9 kPa에서 14.4 kPa로 감소하였으며, 호칭 100A인 경우 171.0 kPa에서 14.2 kPa로 감소하여 기술기준에 적합한 압력손실 값을 얻을 수 있었다.