• 한국식품영양과학회지
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• 제41권1호
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• pp.73-78
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• 2012

트랜스 지방 과다섭취는 심혈관계 질환의 위험인자이다. 이 연구는 녹차의 섭취가 대표적인 트랜스 지방인 elaidic acid의 소장 흡수율에 미치는 영향을 조사하기 위해서 설계하였다. 소장 지방 흡수를 in vivo 상태에서 측정하기 위해서 흰쥐의 '소장지방흡수모델(mesenteric lymph duct cannulated rat model)'을 이용하여 십이지장주입관(intraduodenal catether)과 림프채취관(lymph duct cannula)을 각각 십이지장과 소장 림프관에 설치하였다. 십이지장주입관으로 주입된 지질유화액은 $180.0{\mu}mol$ elaidic acid, $400.0{\mu}mol$ triolein, $20.7{\mu}mol$ cholesterol, $3.1{\mu}mol$ a-tocopherol, $396{\mu}mol$ sodium taurocholate 그리고 24 mL PBS 용액을 기본성분으로 했고 이 지질유화액만 공급받은 동물을 대조군(control), 녹차추출물이 추가된 지질유화액을 공급받은 동물을 녹차군으로 하였다. 지질유화액은 시간당 3 mL씩 8시간 동안 주입하였고 동시에 소장 림프관에 설치된 림프채취관으로 분비되는 림프 시료를 매시간 8시간 동안 채취하여 분석하였다. 결과적으로, 8시간 동안 소장 림프채취관으로 분비된 림프의 양은 녹차에 의해서 유의적으로 감소하였고 elaidic acid의 흡수율(분비율) 또한 녹차에 의해서 유의적으로 감소하였다. 콜레스테롤, 올레산, 인지질의 흡수율도 녹차에 의해서 유의적으로 감소하였다. 이상의 결과들은 녹차가 elaidic acid 뿐만 아니라 기타 주요 식이성 지방들의 소장흡수를 억제하는데 효과적인 수단이 될 수 있다는 것을 증명한 연구라 판단된다.

• 한국지열·수열에너지학회논문집
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• 제10권4호
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• pp.15-24
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• 2014

This study conducted a computational fluid dynamics(CFD) analysis to find an appropriate diameter or sectional area of air ducts and fluid pipes which have an electromagnetic pulse(EMP) shied to protect indoor electronic devices in special buildings like military fortifications. The result shows that the optimized outdoor air intake size can be defined with either the ratio of the maximum air velocity in the supply duct to the air intake size, or the shape ratio of indoor supply diffuser to the outdoor air intake. In the case of water channel, the fluid velocity at EMP shield with the identical size of the pipe, decreases by 25% in average due to the resistance of the shield. The enlargement of diameter at the shield, 2 step, improves the fluid flow. It illustrated that the diameter of downstream pipe size is 1step larger than the upstream for providing the design flow rate. The shield increases friction and resistance, in the case of oil pipe, so the average flow velocity at the middle of the shield increase by 50% in average. In consideration of the fluid viscosity, the oil pipe should be enlarged 4 or 5 step from the typical design configuration. Therefore, the fluid channel size for air, water, and oil, should be reconsidered by the engineering approach when EMP shield is placed in the middle of channel.

• 한국CDE학회논문집
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• 제17권1호
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• pp.54-61
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• 2012

In this paper, we performed numerical analysis to improve the heat exchange efficiency of wasted heat recovery ventilator which has a delivery and a exhaustion fan. One of the most important design factors that affect the efficiency of heat exchange is uniform counter-flow between inbound and outbound air flows. We had simulated several types of porous plates which were installed at air intake area. With plate having 45 degrees of installation angle and 15 mm diameter holes which are uniformly arranged, we can generate a uniform air flows at the area of porous media where inbound and outbound air flows are cross over. In addition, we installed a duct to reduce vortex flows at the outlet and to discharge exhaust airs rapidly. By using the proposed numerical assessment, we expect the improvement of the heat exchange efficiency of ventilator.

• Journal of Advanced Marine Engineering and Technology
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• 제28권7호
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• pp.1138-1144
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• 2004

In order to improve engine performance while overcoming the weak points of Pulse and MPC(Modular Pulse Converter) turbocharging system, a new turbocharging system. "Hi-Pulse system", has been introduced and developed for medium speed diesel engine. HYUNDAI HiMSEN engines. Hi-Pulse system is to utilize not only the benefits of MPC system at higher load but also the ones of Pulse system at lower load. As for the results. the specific fuel oil consumption and NOx emission were lowered compared with the Pulse and MPC system. Performance simulation were carried out to optimize intake and exhaust timing and exhaust duct arrangement and to improve the performance of Hi-Pulse system engine.em engine.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 추계학술대회논문집
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• pp.78-83
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• 2003

General algorithm is developed for the prediction of internal flow-induced noise. This algorithm is based on the integral formula derived by using the General Green Function, Lighthills acoustic analogy and Curls extension of Lighthills. Novel approach of this algorithm is that the integral formula is so arranged as to predict frequency-domain acoustic signal at any location in a duct by using unsteady flow data in space and time, which can be provided by the Computational Fluid Dynamics Techniques. This semi-analytic model is applied to the prediction of internal aerodynamic noise from a throttle valve in an automotive engine. The predicted noise levels from the throttle valve are compared with actual measurements. This illustrative computation shows that the current method permits generalized predictions of flow noise generated by bluff bodies and turbulence in flow ducts.

• 한국추진공학회지
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• 제10권4호
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• pp.100-108
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• 2006

실험적인 연구가 흡입구와 배기구 성능을 평가하는 일반적인 방법이나 이는 고가이며 많은 시간이 소요된다. 따라서 소요 시간과 계산을 절약하는 방법으로 전산 유체 역학적 수치 모사가 실험적 연구로 대체할 수 있다. 그러므로 본 연구는 3차원 형상 모델을 이용하여 흡입구와 배기구의 구성품 성능을 연구하는 것을 목표로 하였다. 본 연구에서 특정한 흡입구 및 배기구를 유동가시화 기능을 갖는 전산유체 역학적 프로그램을 이용하여 손실 및 유동장을 예측하기 위해 모델링 및 해석이 수행되었다. 모델링된 기하학적 자료를 필요로 하는 과정이 설계과정에서 설계 개선 가능성을 위해 요구되었다. 또한 특정 터보축 엔진의 장착 성능이 예측된 흡입구, 배기구 및 기타 보기 손실을 가지고 평가되었다.

• Journal of Korean Biological Nursing Science
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• 제11권2호
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• pp.167-175
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• 2009

Purpose: The purpose of this study was to examine the prevalence and factors on Irritable Bowel Syndrome (IBS) symptoms in university students. Methods: This study was descriptive survey research. The subjects were 187 university students from one university. The exclusion criteria were 1) had GI surgery 2) had severe physiologic or psychologic problems 3) had liver, bile duct, pancreatic, and intestinal disease that required treatment. The ROME III was used to diagnose IBS. Sociodemographic characteristics, general health state by SF-36, psychological health by SCL-90-R, stress by perceived stress scale, sleep disturbance by Korean sleep scale, and diet habits were measured. Data were analyzed by using SPSS 17.0. Results: Seventeen students (9.1%) had IBS by ROME III criteria, but 46% had some GI problems at that time. Abdominal pain or discomfort continued for last six months or more in 14.3%. Fiber intake, obsessive-compulsiveness, hostility, psychoticism, global severity index, positive symptom distress, role physical, bodily pain, social functioning, and mental health were significantly different between IBS group and Non IBS group. Conclusion: Over nine percent of the students were diagnosed by Rome III criteria, and almost half of them had some GI problems. Diet, personality, general health state, and psychological health were factors of IBS.

• 한국소음진동공학회논문집
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• 제14권4호
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• pp.310-318
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• 2004

For many industrial problems originating from aerodynamic noise, noise prediction techniques, reliable and easy to apply, would be of great value to engineers and manufacturers. General algorithm is presented for the prediction of internal flow-induced noise from quick opening throttle valve in an automotive engine. This algorithm is based on the integral formula derived by using the General Green Function, Lighthill's acoustic analogy and Curle's extension of Lighthill's. Novel approach of this algorithm is that the integral formula is so arranged as to predict frequency-domain acoustic signal at any location in a duct by using unsteady flow data in space and time, which can be provided by the Computational Fluid Dynamics Techniques. This semi-analytic model is applied to the prediction of internal aerodynamic noise from a throttle valve in an automotive engine. The predicted noise levels from the throttle valve show good agreement with actual measurements. The results show that the dipole noise is dominant in this phenomena and the origin of noise sources is attributed to the anti-vortex lines formed in the down-stream from a throttle valve. This illustrative computation shows that the current method permits generalized predictions of flow noise generated by bluff bodies and turbulence in flow ducts.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.706-710
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• 2008

The experiment of dome port cover under shock impact is performed with shock tube. The dome port cover blocked intake air duct up from the solid propellant during air breathing vehicle speed reach Mach 2.0. When the air breathing vehicle reach Mach 2.0, the inlet cover is removed and the dome port cover is broken to pieces by detonator or pressure of inlet air. Thus the dome port cover not only must stand the pressure of combustion chamber but also easy to break from the RAM pressure. In this study, a fracture evaluation on the $Al_2O_3$ ceramic spherical dome and circular plate port under impact has been presented. Ceramic were supported by the rigid body and a couple of O-ring. The Mooney-Rivlin model have been used to describe behaviors of both O-ring. And spherical dome and circular plate fracture results of the LS-DYNA code using Johnson-Holmquist(JH-2) constitutive equation was compared.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2013년도 추계학술대회 논문집
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• pp.119-123
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• 2013

We conduct the research for reducing aeroacoustic noise occurred when a vehicle operates in high speed situation without modifying the structural configuration such as deforming A-pillar's side curvature. We introduce PAU (Pneumatic Auxiliary Unit) which is a sort of air duct using intake air through radiator grill. According to our research, we can reduce overall noise levels around the surface of HSM (Hyundai Simplified Model). When a vehicleruns 100km/s, area-weighted acoustic power level (AWAPL) indicates 33dB without PAU. However with PAU, coverall AWAPL is decreased to 29dB which means we can improvesilentness approximately 12% compared to ordinary case. Moreover we conduct similar implementation to steering situation especially about yawing. In varioussituations, -10, 0, 10 degree of yawing, we observe 10% reduction in the upstream region of HSM but little increase in downstream region. It seems that inlet air overlap turbulent kinetic energy to surrounding flow. Even though downstream region's noise is louder than upstream region, overall AWAPL is still lower than conventional condition. We also apply this scheme to the real vehicle situation, then we get reasonable output which can support our research outputs.