• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.15 no.1
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• pp.50-58
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• 2003

An analytical study was carried out to investigate the performance of an oil pumping system of a variable speed compressor using a commercial CFD program. The simulations for the oil supplying system with the oil and air mixture were performed by varying compressor speed from 40 Hz to 90 Hz. Comparing the predicted with the measured data on the modified scroll compressor validated the simulation model. The predicted results were consistent with the test data with a maximum deviation of 12.8%. The oil flow rate significantly increased with a rise of compressor speed due to a higher oil flow rate from the swing pump and a greater centrifugal force on oil gallery.

• 기계와재료
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• v.22 no.1
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• pp.54-64
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• 2010

공작기계의 고속화, 다축화, 복잡화에 따른 열변형 오차가 공작기계에서 발생하는 오차의 대부분을 차지하고 있다. 이러한 열변형 오차를 최소화 하기 위해 공작기계의 발열부에 차가운 오일을 공급하여 냉각함으로써, 열변형을 제거하는 장치가 오일쿨러이다. 오일쿨러는 제어 방법에 따라 On-off, 가스 바이패스, 인버터 방식 등이 사용된다. 초정밀 공작기계에는 주로 가스 바이패스 및 인버터 방식이 사용되는데, 인버터 방식의 경우 고가(高價)인 관계로 주로 옵션 형태로 사용된다. 가스 바이패스 방식 오일쿨러는 인버터 방식에 비해 가격이 저렴하고 구조가 간다하며 정밀한 온도제어를 할 수 있지만 부하가 낮은 경우 구조적인 한계로 인해 온도제어 불안정을 발생시킨다. 본 연구에서는 기존 바이패스 방식 오일쿨러에서 나타나는 문제점을 해결하고 보다 정밀한 온도제어를 위해 2개의 전자밸브를 갖는 듀얼 밸브 방식 오일쿨러 시스템을 개발하였다. 개발된 듀얼 밸브 오일쿨러 시스템의 성능검증을 위해 정격운전, DIN 8602 규격, ISO/DIS 230-3 운전모드에서 성능을 비교/분석하였다.

• Transactions of the Korean Society of Automotive Engineers
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• v.12 no.6
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• pp.90-95
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• 2004

In this study, for the crankshaft bearing design adapting discontinuous oil supply system, analyses were conducted to determine the lubrication characteristics such as oil flow rate and increase of oil temperature at main bearing and connecting rod bearing. Additionally, supplied oil pressure and temperature effects on the bearings were simulated to figure out lubrication characteristics on the bearings. Finally the effects of increasing the bearing width and clearance were introduced on the lubrication characteristics.

• Journal of the KSME
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• v.32 no.11
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• pp.947-954
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• 1992

이 글에서는 엔진 윤활 시스템해석 프로그램의 구성 요인 및 프로우차트를 열거했으며 이렇게 만들어진 프로그램을 이용하여 엔진의 개선 및 신엔진 개발 시에 매개변수를 변화시켜가며 오일 유로의 설계와 요구되는 오일량을 결정하여 최적의 윤활시스템을 설계할 수 있다고 본다. 참고로 밸브시스템의 정상적인 작동을 유지하는 상태에서 요구되는 토출 유압과 유량이 줄어들면 오일 펌프의 용량을 줄일 수 있고 그로 인해 오일 펌프 구동손실도 줄일 수 있다. 또한 최적 유량이 공급될 때 엔진 구동손실을 최소화할 수 있다. 더나아가 본 해석으로 얻은 최적화된 유량이 만족 된 이상적인 윤활 부위의 치수가 결정된 상태에서 운동부의 마찰을 최소화하는 엔진 마찰의 수치해석적 모델을 개발하는 것도 흥미있는 과제이다. 또한 간단한 테스트 리그 제작에 의한 각 윤활 부품에서의 압력-유량 관계 실험식의 정확도를 높이는 것도 앞으로의 과제이다.

• 한국신재생에너지학회:학술대회논문집
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• 2009.11a
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• pp.537-540
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• 2009

오일샌드는 아스팔트와 같은 중질유를 10% 이상 함유한 모래 또는 사암으로서, 겉으로 보기에는 시커먼 흙이나 모래처럼 보이나 내부에는 모래(점토)와 같은 광물질이 70~80%, 에너지원으로 활용이 가능한 중질유 성분인 bitumen이 10~18%, 물이 3~5% 정도 혼합되어 있다. 본 연구에서는 이러한 오일샌드 활용방안 개발을 위하여 오일샌드로부터 bitumen의 추출 및 증류 특성에 대한 시험을 진행하였으며, 가스화를 통한 합성가스 제조, 합성가스 중 분진제거 및 탈황, CO/$H_2$비 제어를 위한 합성가스 전환 등의 시험을 진행하였는데, pilot급 시스템을 이용한 합성가스 제조 시험 결과 중질잔사유를 5~7 kg/h 공급하는 조건에서 CO 40~50%, $H_2$ 20~30%, $CO_2$ 10~20% 조성의 합성가스 18~22 $Nm^3$/h를 제조하였다.

• Transactions of the Korean Society of Automotive Engineers
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• v.12 no.3
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• pp.37-43
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• 2004

Engine lubrication system is generally affected by vehicle driving conditions; acceleration, braking deceleration, and cornering. The oil supply system such as oil pan, baffle plate, and oil pick-up pipe should be optimized to cope with severe driving conditions. The main purpose of this paper is to understand the effect of the engine tilting angle on the oil supply system using engine tilting test rig. For the purpose, the oil pressure fluctuation and oil aeration in the main gallery are measured at various engine tilting angles. In addition, the oil flow is visualized by using transparent oil pan to investigate the cause of the formation of oil aeration. The test results show there is a strong correlation between the main gallery oil pressure fluctuation and oil aeration. It is also found that the visualization technique is helpful to stabilize the oil supply system at severe driving conditions.

• The Journal of the Korea institute of electronic communication sciences
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• v.9 no.1
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• pp.83-90
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• 2014

In this paper, we address the problem of designing and implementing an oil pump control system driven by a brushless DC (BLDC) motor. The proposed oil pump plays the role of providing fuel to the engine clutch and transmission of hybrid vehicles. Main consideration is given to enhancing response feature and accuracy of the oil pump by simplifying the controller that is driven by a BLDC motor under PWM voltage control, which is a standard control method for BLDC motors. The proposed control scheme also helps to increase efficiency and reliability of the oil pump system. To validate the performance of the proposed system, we conduct experiments on BLDC motor speed control and oil pump operations.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.1
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• pp.585-591
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• 2017

Turbocharging is widely used in diesel and gasoline engines as an effective way to reduce fuel consumption. But turbochargers have turbo-lag due to mechanical friction losses. Bearing friction losses are a major cause of mechanical friction losses and are particularly intensified in the lower speed range of the engine. Current turbochargers mostly use oil bearings (two journal bearings and one thrust bearing). In this study, we focus on the bearing friction in the lower speed range. Experimental equipment was made using a drive motor, load cell, magnetic coupling, and oil control system. We measured the friction losses of the turbocharger while considering the influence of the rotation speed, oil temperature, and pressure. The friction power losses increased exponentially when the turbocharger speed increased.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2007.11a
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• pp.991-994
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• 2007

Since the year of 2003, the overseas plant market has grown by an average of 6% per year. It is because of the increase of oil-money, economic growth of BRICs, and the result of heavy competition among the countries which demands a great amount of resources for the purpose of resource securing. Such a situation is expected to be continued for a while. The procurement is one of critical functions for successful completion of a plant project. For effective procurement, it is required to manage vendor's information efficiently. But most of the vendor management systems deal with simple general information and performance data about vendors. In this sense, this paper proposes a vendor management system which can be used within a decision-making system. The system uses existing DB and makes the close relationship with the vendors. This paper will also reduce risks and difficulties in the process of selecting the proper vendors and will increase efficiency of procurement process in electronic bidding between companies.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.7
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• pp.9-15
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• 2018

The turbochargers, which are used widely in diesel and gasoline engines, are an effective device to reduce fuel consumption and emissions. On the other hand, turbo-lag is one of the main problems of a turbocharger. Bearing friction losses is a major cause of turbo lag and is particularly intense in the lower speed range of the engine. Current turbochargers are mostly equipped with floating bearings: two journal bearings and one thrust bearing. This study focused on the bearing friction at the lower speed range and the experimental equipment was established with a drive-motor, load-cell, magnetic coupling, and oil control system. Finally, the friction losses of turbochargers were measured considering the influence of the rotating speed from 30,000rpm to 90,000rpm, oil temperature from $50^{\circ}C$ to $100^{\circ}C$, and oil supply pressure of 3bar and 4bar. The friction power losses were increased exponentially to 1.6 when the turbocharger speed was increased. Friction torques decreased with increasing oil temperature and increased with increasing oil pressure. Therefore, the oil temperature and pressure must be maintained at appropriate levels.