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불균일 표면전하응 지닌 미소채널 내에서의 혼합에 관한 수치
송경석(Kyungsuk Song),이도형(Dohyung Lee) 대한기계학회 2003 대한기계학회 춘추학술대회 Vol.2003 No.11
Electroosmotic flow induced by an applied electrostatic potential field in microchannel is analyzed in this<br/> study. The electroosmotic flow is an alternative to pressure driven flow in microchannels, but the usage has<br/> been limited to the simple cases. In this study, We analyze electroosmotic flow driven by inhomogeneous<br/> surface charge on the channel wall. The surface charge varies along a direction perpendicular to the electric<br/> field in order to generate the electroosmotic flow. A numerical results substantiate the highly efficient mixing<br/> performance. It is highly the beneficial to fabrication process since only straight microchannel rather than<br/> complex geometry is enough to yield efficient mixing.
고집적 플라스틱 오일쿨러의 튜브 배열에 따른 열전달 특성
송경석(Kyungsuk Song),허형석(Hyungseok Heo),배석정(Sukjung Bae),이헌균(Heonkyun Lee) 한국자동차공학회 2006 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
It has been argued that the use of plastics can cause problems during design and manufacture owing to their low strength, relatively poor thermal conductivity and large thermal expansion. However, the advantages of plastics e.g., corrosion resistance, low cost, curtailment of weight, design flexibility etc., can compensate abundantly for the disadvantages. This study analyzes and compares the heat transfer performance characteristics of automotive compact oil cooler composed of plastic tube bundle with conventional metal oil cooler on the same core area basis as diameter and tube thickness and number of tube and tube arrangement varies. The performance analyses are accomplished by use of computational fluid dynamics program Fluent 6.2, which is verified and compared with the results of performance tests. The results of analyses is coincided with that of experiments. Flow pattern at air side according to tube arrangement is dominant factor which affects heat dissipation in case of similar total heat transfer surface area.
송경석(Kyungsuk Song),허형석(Hyungseok Heo),배석정(Sukjung Bae),이헌균(Heonkyun Lee) 한국자동차공학회 2006 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
Gerotor type pump is widely used as automotive part that provide cooling, lubrication and filtration. That is positive displacement device using nested hypocycloid gear elements as their pumping mechanism. Due to the complexity of flows inside an oil pumps in both the geometry and physics, the oil pumps design was dominated by simple analytical methods. It has been argued that the numerical analysis of gerotor pump can cause problems during analysis owing to rotor clearance, grid and variable volume. In this paper, an automotive gerotor pump is analyzed using FLUENT 6.2. The goal of this study is to visualize the flow through gerotor type oil pump. The dynamic mesh model with 2.5D meshing was used to model rotor motion. These simulation accurately predict time dependant pressure and mass flowrate. CFD simulation of this paper can be used to better understand its performance.
송경석(Kyungsuk Song),양승훈(SeungHun Yang) 대한기계학회 2014 대한기계학회 춘추학술대회 Vol.2014 No.6
2004년 UN 안보리결의 1540호를 통해 전략물자 수출통제제도는 국제 규범화 되었다. 이는 기업의 통상적인 제품의 수출행위 뿐만 아니라, 일상적인 연구활동에도 적용된다. 기계공학 부문에서도 비교적 많은 기술이 전략물자로 등재되어 있다. 이 글에서는 기계공학 부문에서 등재된 기술에 대해 세부적으로 열거함과 동시에 이들 기술을 관리하는 방안에 대해 기술하고자 한다. Korea export control system to prevent the proliferation of weapons of mass destruction(WMD), as well as their means of delivery is an instrument in meeting national obligations under UN security council resolution 1540. This export control rule applies to R&D activities as well as ordinary export activities. So researcher must always be careful of technology transfer. Strategic technology includes a field of mechanical engineering. With this point of view, I address the challenges of strategic technology in field of mechanical engineering and I offer suggestions for managing these technologies.
응축기 전면의 유동 불균일도를 고려한 자동차용 에어컨시스템 해석 프로그램 개발
배석정(Sukjung Bae),허형석(Hyungseok Heo),송경석(Kyungsuk Song) 한국자동차공학회 2006 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
Recently, circumstances for heat exchanger (condenser) in automotive air conditioning system to work have become worse due to curtailment of engine room to enlarge cabin space, abridgement of grille opening to enhance aerodynamic efficiency and diversification of heat source for future fuel cell vehicles. The periods to develope the new cars have become increasingly shorter. These situations have brought the need of performance prediction technique for air conditioning system on board at design stage. This study has developed simulation program for air conditioning system with inlet air flow maldistribution of condenser. The program takes inputs such as air inlet velocity and temperature distribution of condenser and geometries of system components and gives various outputs such as temperatures, velocities and pressures of both fluids - air and refrigerant. Experiments utilizing environmental wind tunnel have been conducted for various working conditions of air conditioning system. The results from program analyses have good agreements with that from experiments. The flow maldistribution in air temperature and/or velocity deteriorates the system performance up to 5%.
특성 방법을 이용한 Fuel Rail 압력맥동 특성 해석 프로그램 개발
배석정(Sukjung Bae),허형석(Hyungseok Heo),이헌균(Heonkyun Lee),송경석(Kyungsuk Song),박시우(Seewoo Park),김보겸(Bokyoum Kim) 한국자동차공학회 2006 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
In the return less fuel rail system of MPI engine, pulsation damper is commonly mounted for the purpose of diminution of pressure pulsations and jarring noise. But, pulsation damper is too expensive for all the advantage. Therefore, the studies are on the increase to develop fuel rail to diminish pulsations with integrated damping effect. This paper deals with numerical approach using method of characteristics to design fuel rail to reduce pulsations with self-damping effect. Primarily, the pressure pulsation characteristics is investigated with aspect ratio of cross section, wall thickness, and materials of fuel rail. Secondarily, sweep test simulation of fuel rail for in-line engine is performed as engine speed increases to find out certain engine speed where pressure pulsation peak is observed. A high aspect ratio or thin wall is found to absorb the pressure pulsations effectively. The fuel rail made of aluminum is effective for reduction of pressure pulsation than that of low-carbon steel. Pressure pulsation peak is observed at the vicinity of certain engine speed where single-injector oil hammer simulation predicts that resonance would occur.
Fuel Rail의 설계 인자별 압력맥동 특성에 관한 연구
허형석(Hyungseok Heo),배석정(Sukjung Bae),이헌균(Heonkyun Lee),송경석(Kyungsuk Song),박시우(Seewoo Park),김보겸(Bokyoum Kim) 한국자동차공학회 2006 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
In general, pulsation damper is installed in fuel rail for conventional MPI engine to decrease undesirable cabin noise. However, pulsation damper is so expensive that there are prevailing studies to reduce fuel pressure pulsations with integrated damping effect. This paper is one of basic studies for development of fuel rail to abate pulsations with self-damping effect. Primarily, the pressure pulsation characteristics was investigated with aspect ratio of cross section, wall thickness, and materials of fuel rail. A high aspect ratio or thin wall was found to absorb the pressure pulsations effectively. But volume effects on the fuel pressure pulsation reductions were not especially significant than cross section effects because volume increment rate is larger than pressure pulsation reduction rate. The fuel rail made of aluminum is effective for reduction of pressure pulsation than that of low-carbon steel. Pressure change period increases on the basis of same lengths of supply line and fuel rail as the volume is enlarged and/or the thickness of wall is thinned.