• Journal of Chest Surgery
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• 제22권4호
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• pp.698-704
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• 1989

We experienced the seven cases of penetrating and non-penetrating cardiac injuries combined with cardiac tamponade from June 1986 to June 1989 at Seoul and Chun-An Hospital of SOONCHUNHYANG medical college. The results were as follows. l. In sex distribution, 7 cases were male. In age distribution, The fourth decades occupied about 58 % of all cases. 2. In mode of injury, 4 cases were stab wounds, 1 case penetration by metallic fragment, 2 cases blunt chest trauma. 3. We routinely checked the CVP with subclavian vein catheterization in case of suspicious cardiac tamponade. Significant increments were showed in 4 cases. 4. Becks triad [low blood pressure, raised central venous pressure, distant heart sound] were recorded in 43 % of the cases with proven tamponades. 5. The sites of injury included RV in 4 cases, LV in 1 case, RA in 1 case and branch of RCA in 1 case. The RV injuries were the most common. 6. Coronary artery damage occurred in 2 cases. LADA was severed in 1 case combined with RV rupture and branch of RCA was torn 1 case. 7. Pericardiocentesis was performed 1 case at another hospital before referring to our hospital. We have never used the procedure because we think that it is potentially dangerous with no clear benefit. 8. Subxyphoid pericardial window was performed in 2 cases of severe cardiac tamponade. We have employed this method to stabilize the patients who had systolic hypotension. 9. Surgical approaches were performed with median sternotomy in 3 cases, thoracotomy in 4 cases. 10. We undertook the simple closure in 6 penetrating cardiac wounds. The removal of impacted metallic fragment was performed under the cardiopulmonary bypass. Simple ligation was performed in 2 cases of coronary artery severance 11. One patient with no sign of life was urgently intubated and undertaken an emergency room thoracotomy on the stretch car without antiseptic preparation. The cardiorrhaphy in 6 cases were performed in the operating theater 12. One patient undertaken emergency room thoracotomy did not survive due to refractory hypovolemic shock. But the remaining 6 patients recovered.

• 한국주조공학회지
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• 제32권2호
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• pp.65-74
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• 2012

In this paper, we present the results of our studies on optimal die design towards development of a vacuum die casting process to fabricate fuel cell bipolar plate with micro-channel array. Cavity and overflow shape is designed by computational filling analysis of MAGMA soft. Optimal die design consists of seven overflows at the end of cavity and three overflows at each side wall of cavity. The molten metal that passed the gate and reached the side wall flowed into the side overflow, no turbulent flow occurred, and the filling behavior and velocity distribution were uniform. In addition, partially solidified molten metal passing through the channel was perfectly eliminated by overflow without back-flow. When vacuum pressure, injection speed of low and high region was 300 mbar, 0.3 m/s and 2.5 m/s respectively with Silafont 36 die casting alloy, sound sample without casting defects was obtained. The experimental results are nearly consistent with simulation results.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2008년도 제30회 춘계학술대회논문집
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• pp.18-21
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• 2008

로켓엔진 연소기의 음향 안정성 향상을 위해 고안된 반파장 공명기의 음향학적 설계를 실험적으로 연구하였다. 표준 음향시험 절차에 따라 음향파 응답 신호가 측정되었다. 신호를 토대로, 감쇠인자와 흡음계수가 정량적으로 평가되었고, 이로부터 공명기의 음향감쇠 성능을 파악하였다. 공명기의 직경과 개수, 분포가 공명기의 설계 인자로 채택되었다. 직경이 증가함에 따라 음향감쇠 효과가 증가하였다. 경계흡수 계수가 감소함에 따라 최적 공명기 개수가 감소함을 알았다. 공명기의 open-area 비가 최적값을 초과할 때 과감쇠가 발생하였고, 이로 인해 음향 감쇠 효과가 저하됨을 관찰하였다.

• 한국소음진동공학회논문집
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• 제13권10호
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• pp.743-750
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• 2003

The equivalent source method(ESM) is used for the calculation of the internal pressure field for an enclosure which can have arbitrary boundary conditions and nay include internal objects which scatter the sound field. The advantage of using ESM is that it requires relatively low computing cost and is easy to model the internal diffracting objects. Typical ESM modeling uses two groups of equivalent source positions. One group includes the first order images of the source inside the enclosure. The Positions of the other group are usually on a spherical surface some distance outside the enclosure. The normal velocity on the surfaces of the enclosure walls is evaluated at a larger number of positions than there are equivalent sources. The sum of the squared difference between this velocity and the expected is minimized by adjusting the strength of the equivalent sources. This study is on the optimal far field sources positions when using the equivalent source method. In general, the far field sources are evenly distributed on a surface of a virtual sphere which is centered at the enclosure with a sufficiently large radius. In this study. optimal far field source locations are searched using simulated annealing method for various radii of spheres where far field sources are located. Simulation results showed that optimally located sources with adequate distance away from the enclosure center gave better result than sources with even distribution even with a smaller number of far field sources.

• 신재생에너지
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• 제8권2호
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• pp.44-51
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• 2012

The aim of this paper is to examine the hydraulically optimized camber of a blade. Prior studies have tried to determine the sound method of design on small-hydro turbines. These have appeared to realize a reasonably efficient small-hydro turbine. Nonetheless, specific and accurate design data have not as yet been established for the shape of the runner blade. Hence, this study examines the performance characteristic of an axial propeller turbine with 0~8% camber variations. The results of output power, efficiency, and pressure distribution of the turbine are graphically depicted. The definition of camber refers to the NACA airfoil. The commercial finite element analysis (FEA) packages, ANSYS, and CFX are used in this study. The results revealed the performance characteristics on small-hydro turbine and suggested a highly efficient section shape of the runner.

• 한국추진공학회지
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• 제12권3호
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• pp.34-40
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• 2008

로켓엔진 연소기의 음향 안정성 향상을 위해, 반파장 공명기의 음향학적 설계인자를 실험적으로 연구하였다. 표준 음향시험 절차에 따라 음향파 응답 신호가 측정되었다. 감쇠인자와 흡음계수가 정량적으로 평가되었고, 이로부터 공명기의 음향감쇠 성능을 파악하였다. 공명기의 직경과 개수, 배치, 연소실의 직경이 설계 인자로 채택되었다. 공명기 직경이 증가함에 따라 음향감쇠 성능이 증가하였다. 연소실 단면에 대한 공명기의 면적비가 최적 값을 초과할 때 과감쇠가 발생하였고, 이로 인해 음향 감쇠 성능이 저하됨을 확인하였다. 공명기 직경이 증가할수록 작은 면적비에서 최적 흡음성능이 달성되었다.

• 한국소음진동공학회논문집
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• 제25권8호
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• pp.539-545
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• 2015

Intense acoustic load is generated when a launch vehicle lifts off, causing the damaging vibrations at the launch vehicle or satellite within the fairing. This paper is concerned with the prediction of lift-off acoustic loads for a launch vehicle. As a test example, the lift-off acoustic load on the Korean launch vehicle, NARO, is predicted by the existing calculation tool, the modified Eldred's second method. Although the acoustic sources, assumed as point sources, are to be located along the center line of the exhaust plume when using the Eldred's prediction method, the exact location of the deflected center line of exhaust gas flow is not usually known. To search for the most appropriate source positions, six models of source line distribution are suggested and the acoustic load prediction results from these models are compared with the actual measurements. It is found that the predicted sound pressure spectrum of the Naro is the most similar to the measured data when the centerline of the turbulent kinetic energy contour is used as the source line.

• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2009년도 추계학술발표대회 논문집
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• pp.123-129
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• 2009

In these days, the green building movement caused by the energy crisis is increasing, passive design is getting mere and more attention as it provides many possibilities for energy conservation. Moreover, with the increasing social intention for healthy life, the demand for indoor air Quality is increasing in Korea. As result, the ventilation system which can provide the sound outdoor air constantly has been obliged in Korea. So, the hybrid system which using natural power and mechanical power and makes up for the shortage of mechanical and natural ventilation attracts people's attention in Korea. As a hybrid ventilation system, in this study, the stack effect driven hybrid ventilation system in high-rise residential building will be suggested. And in this paper, the theoretical review for hybrid ventilation system suggested in this study will be addressed. Especially, the characteristics of pressure distribution and airflow caused by stack effect in high-rise residential building and the possibility of natural ventilation as results of stack effect will be described.

• 대한기계학회논문집B
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• 제40권5호
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• pp.321-327
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• 2016

본 연구에서는 고속 회전을 하는 진공청소기용 원심홴의 공력성능 향상을 위해 에어포일 임펠러(Airfoil Impeller)의 적용을 검토 및 연구하였다. 에어포일 최대두께 및 최대두께 위치에 따라 3종의 에어포일 임펠러를 제시하였고, 이때 C4 에어포일 두께분포를 이용하였다. 에어포일 임펠러의 성능 평가는 전산유체역학(Computational Fluid Dynamics) 해석과 흡입일률시험을 통해 수행되었다. 이를 통해 에어포일 형상 적용 시 기존 블레이드 형상에 비하여 임펠러 블레이드 압력면과 디퓨져 블레이드 압력면에서 발생하는 유동박리가 크게 줄어드는 것을 확인하였다. 그리고 이로 인해 기존 원심홴에 비하여 홴 효율이 약 3% 증가 및 비소음이 약 1.3dB(A) 감소되는 것을 확인하였다.

• Journal of Preventive Medicine and Public Health
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• 제19권1호
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• pp.100-122
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• 1986

Obtaining an available information on health concerns of parents of school-age children and furthermore developing the sound policy for the public on health education, this study was conducted during Nov.-Dec. 1985 in the four selected areas; Seoul, large, middle and small city, and farming and fishery villages for 3,337 parents of schoolchildren in Korea. In this study, parents complected a questionnaire containing 34 items related to health concerns(e.g. drinking alcohol, air pollution, cancer, etc. see Table 4 and Fig. 2). For each health items, respondents were asked to indicate a choice between three levels of concern; 'Very high concern,' 'Moderate concern,' 'Little concern', and 'No opinion'. An analysis of responses indicated that most of the top ten health concerns identified by parents as cancer, abortions among high school students, medical malpractice, water pollution, traffic accidents, air pollution, suicide of parents and homicide of offspring, heart disease, venereal diseases, and high blood pressure in that order. Those health problems about which respondents were least concerned were more closely related to the individual, such as drinking alcohol, smoking, tooth decay, gum disease, underweight, overweight. Of greater concern were more such as water pollution, abortions among high school students, air pollution, accidents, medical malpractice. For cancer, heart disease, high blood pressure, various accidents, environmental pollution, parents showed high concern, however, for health issues which contributed as causative influences such as lung cancer from smoking and liver cirrhosis and traffic accidents from drinking alcohol showed less concern. Relationship between parent's residential areas, educational level and sex distribution and health concern showed little difference, however, for these issues parents identified as relatively high concern. Most parents stowed more concern in sex-related of family-related health issues such as abortions among high school students, suicide of parents and homicide of offspring.