• 한국정밀공학회지
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• 제30권8호
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• pp.839-846
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• 2013

Because the performance of a reciprocating compressor in refrigeration and air-conditioning systems is influenced by the lubrication characteristics of sliding components, the lubrication characteristics between the crankshaft and journal bearing have to be researched for the design and the performance improvement of reciprocating compressors. Thus, the proper supply of lubricant for a lubrication between the crankshaft and journal bearing is essential, and an oil path for lubricant supply is installed in the shaft or bearing. However, in order to guarantee the lubrication performance of the journal bearing, it is necessary to design the position of the oil path. Therefore, it is studied to find the optimum position of the oil path by the analysis of the pressure distribution in the journal bearing. The results show that the position of the oil path is significantly influenced by the pressure distribution of the oil film in the journal bearing.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1995년도 추계학술대회 논문집
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• pp.332-335
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• 1995

Electrification pipe modeled on the oil path of the high power transformer is designed and manufactured. Distributions of oil flow velocity are simulated as spacer form in the electrification pipe. Streaming currents are investigated as each electrification pipe. The surface oil velocity of spacer is small the streaming current.

• 한국식품저장유통학회지
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• 제16권2호
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• pp.246-252
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• 2009

회분식 반응기를 이용해 GMO와 CLA로부터 Lipozyme RMIM의 반응을 통해 DAG 함유 유지를 합성하였다. 합성된 DAG 함유 유지의 조성은 총 DAG의 함량이 61 area%로 나타났으며, MAG, FFA, 그리고 TAG가 각각 30, 3.4 그리고 5.4 area%로 나타났다. 합성된 DAG 함유 유지는 short path distillation을 이용하여 DAG를 분리하였고, DAG를 포함한 증류결과물인 residue부분(DAG oil)의 수율은 46%였다. DAG oil의 조성은 총 DAG 함량이 87.3 area%, MAG와 TAG는 각각 1.5와 6 area%로 나타났으며, FFA는 검출 되지 않았다. DAG oil의 지방산 조성은 oleic acid와 linoleic acid가 각각 54%, 7%로 나타났으며, 특히 반응 기질인 GMO에서는 볼 수 없었던 CLA함량이 31.1%로 나타났다. 또한 불포화도의 척도인 iodine value가 GMO는 82.5인데 반해 DAG oil은 108.8로 증가되었고, 이러한 결과로 효소적 반응을 통해 GMO에 불포화도가 높은 CLA가 결합된 DAG oil이 합성되었음을 알 수 있었다. Short path distillation을 통해 분리된 DAG oil의 황색도 값은 95.5였으나, 탈색 한 후 16.2로 감소하였다. DAG oil의 탈색 전 acid value와 peroxide value는 각각 0.3, 0 이었지만, 탈색 후에는 각각 1.0, 2.57로 다소 증가함을 보였다. SFI(%) 분석 결과 합성한 DAG oil은 $-50^{\circ}C$에서 고체지의 함량이 감소되기 시작하여 $15^{\circ}C$에서 모두 융해되었다. DAG oil은 세 개의 융점 피크를 $-41.2^{\circ}C$, $-25.9^{\circ}C$, $3.8^{\circ}C$에서 나타내었으며, $-17.8^{\circ}C$에서 하나의 결정화 피크를 나타내었다.

• 한국조명전기설비학회지:조명전기설비
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• 제6권5호
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• pp.38-44
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• 1992

In this paper, electrification pipe modeled on the oil path that insulating oil flow in the high power transformer is manufactured in order to prevent the accident cause from streaming electrification generated when insulating off flow at a solid-liquid interface, and the streaming current is measured and analyzed according to the shape of oil path in electrification pipe. From the result of this study, the streaming current increases linearly with increasing of a oil velocity and it increases at lower temperature and decreases at higher temperature than [$46^{\circ}C$]. The smoother the flow of insulating oil is the more the streaming current decreases.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 1997년도 제25회 춘계학술대회
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• pp.176-180
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• 1997

Evaluating an optimum seal design to minimize leakage is concerned in the aspect of flow control. Flow is characterized into five categories according to its leakage path. Effect of geometry and leakage path are evaluated according to variation of sealing geometry. To simulate an oil jet or oil mist type high speed spindle lubrication, the working fluid is regarded as two phases that are mixed flow of oil phase and air phase. Both of the turbulence and the compressible flow model were introduced in CFD(Computational Fluid Dynamics) analysis. This offers a methodological way of enhancement seal design for high speed spindle.

• 한국전기전자재료학회논문지
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• 제29권2호
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• pp.114-119
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• 2016

This paper dealt with the propagation characteristics of acoustic signal in insulation oil for the purpose of improving the reliability of AE (acoustic emission) method used for condition monitoring of oil-immersed transformers. A discharge source was placed in insulation oil and AE sensors ($f_c$ :140 kHz) were attached on the oil tank to study the changes of velocity and propagation path with the depth and distance. The average velocity was 1,436 m/s and the velocity decreased with the increase of depth from the oil surface to 430 mm. The propagation paths were classified into three sections by the shortest reflection path of the detected signal. The minimum distinguishable distance in each section was 70 mm. It was also verified that PD (partial discharge) with a magnitude over than 500 pC can be detected by the AE sensors.

• 대한전기학회논문지
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• 제43권4호
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• pp.594-600
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• 1994

The maximum charge accumulation in transformers caused by streaming electrification is commonly observed on the bottom area of transformer winding(i.e.the oil inlet of transformer winding). It is because turbulent flows occur in this portion of transformers. Consequently, if we are to reduce the maximum charge accumulation of transformers, it is important that we should have a good understanding of the conditions of the occurence of partial turbulent flows in the oil inlet of transformer winding. With this point in mind, a simple flow model was designed in this study in order to simulate oil flow in the insulation ducts of power transformers. As a method for mitigating charge accummulation, attention was given to (a) a flow path design for the improvement of flow conditions, and (b) the charge tendency of the material used this design. The results of this study show that the above method is useful for mitigating charge accumulation.

• 한국정밀공학회지
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• 제14권11호
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• pp.11-16
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• 1997

In the stroke sensitive shock absorber, the oil path is formed along the internal cylinder surface to make the oil flow during the piston's upper-lower reciprocation movement. In constrast with the conventional shock absorbesr which show one dynamic characteristic curve, stroke sensitive shock absorber shows two kinds of dynamic characteristics according to the stroke. In this study, in order to obtain more precise information about design and damping performance analysis, the analysis on the damping force generation process and dynamic behaviour characteristics of stroke sensitive shock absorber are performed by considering the valve characteristics.

• 로봇학회논문지
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• 제2권2호
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• pp.161-167
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• 2007

It is dangerous that an inspector overhauls defects and condition of the inner parts of an oil tanker because of many harmful gases, complex structures, and etc. However, these inspections are necessary to many oil tankers over old years. In this study, we proposed the design of mobile robot for inspection of CAS in oil tanker. The developed CAS inspection mobile robot has four modules, a measurement module of oil tanker's thickness, a corrosion inspection module, a climbing module of the surface on a wall, and a monitoring module. In order to get over at a check position, the driving control algorithm was developed. Magnetic wheels are used to move on the surface of a wall. This study constructed a communication network and the monitoring program to operate the developed mobile robot from remote sites. In order to evaluate the inspection ability, the experiments about performance of CAS inspection using the developed mobile robot have been carried out.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2004년도 학술대회지
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• pp.275-282
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• 2004

The engine bearing transmits the powers from cylinder to crankshaft with small clearance between con-rod and crankpin. The minimum oil film thickness is a significant parameter in the operation of bearing. The contact pressure of bearing should be considered for the reason that elastic deformation of bearing be caused by contact pressure of bearing. There are important factors which are maintaining of minimum oil film thickness expecting of the length of maximum and minimum oil film thickness with changing of the loads to keep running normally. Furthermore, this study is very crucial to develop the design of engine bearing and crankshaft system.