• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2012년도 전기공동학술대회 논문집
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• pp.123-124
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• 2012

Effervescent atomizer in which the liquid is ejected from nozzle with bubble caused by gas injection into the liquid is one of twin-fluid atomizers. Effervescent atomizer is operated with the lower injection pressure and the smaller air flow rate when compared with those of other twin-fluid atomizers. In this study, we attempted experiment study to investigate the atomization characteristics of effervescent atomizer related with the internal flow condition. The nozzle was made with acrylic material to investigate the nozzle internal flow. The macroscopic spray analysis was conducted with internal flow images and spray images. Furthermore, SMD was measured by using the laser diffraction method. According to this study, the internal flow condition changed from bubbly flow to annular flow as the air-liquid mass ratio(ALR) increases. At that time, the atomization characteristics were improved.

• 한국항공우주학회지
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• 제30권7호
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• pp.90-97
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• 2002

희박 상태 비행체 외부 및 추진장치 내부 유동이나 MEMS 장치의 기체유동은 높은 열적 비평형성으로 인해 벽면 슬립모델을 필요로 한다. 조절계수와 벽면속도 구배를 바탕으로 하는 Maxwell 조건이 주로 사용되어 왔지만, 조절계수를 자체적으로 정의할 수 없고, 일차 미분 형태로 인해 실제 적용시 수치적 관점에서 효율적이지 못한 어려움이 있었다. 본 연구에서는 이 문제를 해결하고자 Langmuir의 벽면-기체입자 흡착이론을 이용한다. 벽면온도, 벽면-기체입자간 물리적 힘의 함수인 조절계수를 유도하고, 입자형태의 차이를 감안할 수 있는 물리적 슬립모델을 개발하여 기존 Maxwell 모델과 비교하였다. 또한 내부, 외부, 열유체 유동에 관한 슬립모델의 해석적 해를 실험값과 비교하여 그 유용성을 확인하였다.

• 한국안전학회지
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• 제35권6호
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• pp.32-45
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• 2020

The problem of determining the discharge rates of gases from pressurized vessels through pressure relief devices was dealt with comprehensively. First, starting from basic fluid flow equations, detailed modeling procedures were presented for isentropic nozzle flows and frictional flows in a pipe, respectively. Meanwhile, physical explanations were given to choking phenomena in terms of the acoustic velocity, elucidating the widespread use of Mach numbers in gas flow models. Frictional flows in a pipe were classified into adiabatic, isothermal, and general flows according to the heat transfer situation around the pipe, but the adiabatic flow model was recommended suitable for gas discharge through pressure relief devices. Next, for the isentropic nozzle flow followed by adiabatic frictional flow in the pipe, two equations were established for two unknowns that consist of the Mach numbers at the inlet and outlet of the pipe, respectively. The relationship among the ratio of downstream reservoir pressure to upstream pressure, mass flux, and total frictional loss coefficient was shown in various forms of MATLAB 2-D plot, 3-D surface plot and contour plot. Then, the profiles of gas properties and velocity in the pipe section were traced. A method to quantify the relationship among the pressure head, velocity head, and total friction loss was presented, and was used in inferring that the rapid increase in gas velocity in the region approaching the choked flow at the pipe outlet is attributed to the conversion of internal energy to kinetic energy. Finally, the Levenspiel chart reproduced in this work was compared with the Lapple chart used in API 521 Standatd.

• 한국지반공학회논문집
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• 제38권4호
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• pp.5-20
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• 2022

본 연구에서는 토석류의 유동과 밀도 변화를 분석하기 위해 운동량방정식으로 단순화된 2상 유한체적모델(Landflow 모델)을 구성하였으며, Hershel-Buckley 유동모델을 사용하여 토석류의 내부 및 기저 마찰과 복잡한 지형 및 연행침식을 분석하였다. 또한 토석류 해석 모델을 수치적으로 해결하기 위하여 Harten-Lax-van Leer-Contact(HLLC) 방법을 포함한 관련 유한체적모델을 도입하여 토석류의 경계면에 대한 해를 구하였다. 충격흡수능력, 수치적 등방성, 모델정확도, 질량보존을 검증하기 위해 제안된 모델을 기반으로 원형 댐파괴, 비뉴턴 유체의 댐파쇄 및 다중 토석류 사례분석을 수행하였다. 해석 결과로부터 본 해석모델의 토석류 해석에 대한 수치적 안정성과 정확도를 확인하였다. 또한, 다양한 유동학적 특성의 토석류 흐름을 체계적으로 시뮬레이션하고 토석류 유동특성이 거동에 미치는 영향을 분석하였다.

• Tuberculosis and Respiratory Diseases
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• 제76권6호
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• pp.295-298
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• 2014

Pulmonary systemic arterialization to normal basal lung without sequestration is a rare congenital anomaly. In this rare abnormality, arterialization of the left lower lobe is the most common type. In general, surgical treatments have been performed. Recently, for reducing the complications and risks of surgery, embolization is mainly attempted by using coils. We report a case of 22-year-old male patient with a 10 mm anomalous arterial supply to his normal lung, which is being successfully treated by transcatheter embolization when using the Amplatzer Vascular Plug that has been adapted for the treatment of high-flows and large artery occlusions.

• 대한조선학회논문집
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• 제48권6호
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• pp.544-551
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• 2011

The internal flows of moonpool usually causes huge added resistance on drillships, and those are very complex to analyze. Therefore, not only experimental approaches but also numerical simulations are required for better investigations when dealing with the hydrodynamic problems of moonpool. In the present research, numerical simulations are used to find out why the resistance increases by moonpool on a running drillship. That is, the three-dimensional numerical simulations and model tests are carried out to examine the characteristics of internal flow and added resistance by changing the section of the moonpool in both longitudinal and transverse directions. Finally, based on the present studies, an optimized shape of the moonpool is suggested, which effectively reduces added resistance, and that is confirmed with three-dimensional numerical simulations and model tests.

• 대한한방내과학회지
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• 제25권4호
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• pp.464-472
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• 2004

Aortic regurgitation occurs when there is a leakage of the valve backward into the left ventricle during diastole. Chronic aortic regurgitation may be present for decades before any symptoms occur. The left ventricle is able to compensate for the large volume of blood that flows backward by enlarging the cavity and increasing the thickness of the muscle. This mechanism allows the heart to pump out both the amount of blood required by the body and the blood that has gone backward into the left ventricle. One patient who had chest pain from exercise was treated. He was diagnosed with aortic regurgitation LVH by echocardiography. Signs showed him to be of Taeumin-type within Sasang Constitutional Medicine. He was prescribed Gamijoripewontang for 75 days, and improvement of clinical symptoms were observed. Results support prescription of Gamijoripewontang as an effective treatment for Taeumin-type patients suffering chest pain caused by aortic regurgitation.

• 동굴
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• 제65호
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• pp.39-51
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• 2004

To introduce the typical water caves of the northeastern district in China, the Shenyang Water Cave located in the Shenyang city and the Benxi Water Cave located in the Benxi city of the Liaoning province of the northeastern part of China are presented. The caves are very big and long, and the water flows in the cave to drive the motor boat for tourist watching the beautiful sight in the caves through the year. The geological information and the beautiful internal sight of views in the caves are introduced.

• 한국가시화정보학회지
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• 제22권1호
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• pp.28-33
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• 2024

We visualized the rupturing of liquid films flowing over a disk rotating with large angular velocity. A setup of high speed imaging for liquid flows on dark and reflective surfaces are suggested. From the result, rivulet structures are revealed to be strongly governed by three-dimensional surface structures developed in the film flow. Additionally, unique flow structures including the rivulet sliding and internal meandering are investigated. Generation mechanism of such structures are discussed in terms of the dynamic contact angle theory.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2000년도 제31회 춘계학술대회
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• pp.114-120
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• 2000

EHL analysis of connecting rod bearing is proposed which includes effects of temperature variation in lubrication film. Lubrication film temperature is treated as a time-dependent, two-dimensional variable which is averaged over the film thickness, while connecting rod big end temperature is assumed to be time-independent and three-dimensional. It is assumed that a portion of the heat generated by viscous dissipation in the lubrication Him is absorbed by the film itself, and the remainder flows into the bearing surface. Mass-conserving cavitation algorithm is applied and the effect of variable viscosity is included to solve the Reynolds equation. Simulation results of the connecting rod bearing of internal combustion engine are presented. It is shown that the temperature variation has remarkable effects on the bearing performance. It is concluded that the EHL analysis considering effects of the temperature variation is strongly recommended to predict the bearing performance of connecting rod big end On internal combustion engine.