• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.980-985
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• 2004

This paper shows a performance analysis for conical type sealless cylinders and rod bearings. The pistons without seal have partly cylindrical and conical shapes. 2 dimensional Reynolds equation and FD(finite differential) numerical techniques are utilized for the performance analysis. The relationship among self-centering forces and leakage flows are investigated. Also, optimal design values for a sealless cylinder are presented. A prototype of sealless cylinder which had rod bearing with four pockets, five pockets, and six pockets was manufactured respectively. Leakage flow test is conducted to evaluate performance of piston and rod bearing in sealless cylinder.

• Tribology and Lubricants
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• 제12권4호
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• pp.35-42
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• 1996

The labyrinth seal is one of the widely used non-contact type mechanical seal. Current work was emphasized on the investigation of the air jet effect on the labyrinth seal. To improve the sealing capability of conventional labyrinth seal, air jet was injected against through the leakage flow. In this study, both of the numerical analysis by CFD (Computational Fluid Dynamics) and the experimental measurement were carried out. Both of the turbulence aad the compressible flow model were introduced in CFD analysis. The sealing effect of the leakage clearance and the air jet magnitude were studied in the experiment. The reason of the enhanced sealing was explained as a reduction of effective clearance by jetting air. As a result, the air jet could reduce the effective clearance with a wide range of leakage clearance.

• 전기의세계
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• 제22권1호
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• pp.42-51
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• 1973

The contriving equivalent circuit of single phase induction motor which does not separate the primary leakage reactance and the secondary leakage reactance by the revolving field theory, and the graphically calculating method of the characteristics with T-type circle diagram of three phase induction motor which does not suppose the primary leakage reactance can be drawn up only by the no load test, the lock test, and measuring the resistance of stator winding are suggested in this paper. The method which can calculate the parameters of the equivalent circuit and the characteristics with no load test, lock test and measuring resistance of stator windings is suggested in this paper. Considered the exciting current in lock test, we could calculate very accurate characteristics of the single phase induction motor.

• 전자공학회논문지A
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• 제30A권8호
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• pp.34-41
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• 1993

Effect of high temperature annealing conditions on Ta$_{2}O_{5}$ thin films was investigated. Ta$_{2}O_{5}$ thin films were deposited on P-type silicon substrates by plasma-enhanced chemical vapor deposition (PECVD) using tantalum ethylate. Ta(C$_{2}H_{5}O)_{5}$, and nitrous oxide. N$_{2}$O. The microstructure changed from amorphous to polycrystalline above 700.deg. C annealing temperature. The refractive index, dielectric onstant and leakage current of the film increased as annealing temperature increased. However, annealing in oxygen ambient reduced leakage currents and dielectric constant due to the formation of interfacial SiO$_{2}$ layer. By optimizing annealing temperature and ambient, leakage current lower than 10$^{-8}$ A/cm$^{2}$ and maximum capacitance of 9 fF/${\mu}m^{2}$ could be obtained.

• 한국정밀공학회지
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• 제22권8호
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• pp.42-49
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• 2005

Our purpose is to develop a precision magnetic displacement sensor that has sub-micron resolution and small size probe. To achieve this, we first have tried to establish mathematical models of a magnetic sensor in this paper. The inductance model that presents basic measuring principle of a magnetic sensor is based on equivalent magnetic circuit method. Especially we have concentrated on modeling of magnetic flux leakage and magnetic flux fringing. The induced model is verified by experimental results. The model, including the magnetic flux leakage and flux fringing effects, is in good agreement with the experimental data. Subsequently, based on the augmented model, we will design magnetic sensor probe in order to obtain high performances and to scale down the probe.

• ETRI Journal
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• 제13권2호
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• pp.21-27
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• 1991

Effects of annealing on the dielectric properties and microstructures of thin tantalum oxide film(25nm) deposited on p-type Si substrate with rf reactive magnetron sputtering were investigated. The leakage current density was remarkably reduced from $10^-8$ to $10^-12$ A/$\mum^2$at the electric field of 2MV/cm after rapid thermal annealing(RTA) in $O_2$at $1000^{\circ}C$, while little leakage reduction was observed after furnace annealing in $O_2$ at $500^{\circ}C$. The structural changes of thin tantalum oxide film after annealing were examined using high resolution electron microscope(HREM). The results of HREM show that substantial reduction in the leakage current density after the RTA in $O_2$ can be attributed to crystallization and reoxidation of the thin amorphous tantalum oxide film.

• 에너지공학
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• 제23권4호
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• pp.183-188
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• 2014

Solenoid operated electromagnetic control valve (ECV) using in an external variable displacement swash plate type compressor is widely used for air conditioning control system because of its low energy consumption and high efficient characteristics. ECV controls the entire vehicle air conditioning system by means of a pulse width modulation (PWM) system that supplied from an external controller. Different pressure ports located within ECV has important functions to control the air/refrigerant flow through its internal passages. The flow paths are preciously maintained with acceptable ranges of leakage (gap) between the parts inside it which is followed by effective design and critical dimensioning of its internal features. Therefore, it saves energy losses from the solenoid operation as well as ensures the balance of forces within it. The research paper highlights analysis of the leakages (at different pressure ports) and dimensioning tolerance factors that affects the ECV performance.

• 산업기술연구
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• 제19권
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• pp.101-105
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• 1999

Ultra thin $Ta_2O_5$ gate dielectrics were prepared by RTMOCVD (rapid thermal metal organic chemical vapor deposition) using Ta source $TaC_{12}H_{30}O_5N$ and $O_2$ gaseous mixtures. As a result, $Ta_2O_5$ thin films showed significantly low leakage current compared to $SiO_2$ of identical thickness, which was due to the stabilization of the interfacial layer by NO ($SiO_xN_y$) passivation layer. The conduction of leakage current in $Ta_2O_5$ thin films was described by the hopping mechanism of Poole-Frenkel (PF) type.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2017년도 춘계 학술논문 발표대회
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• pp.240-241
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• 2017

In this stduy, we will references to provide reasonable basis for the test environments applicable to the chemical resistance test covered by KS F 4935 『Injection-type Sealing Materials for Water Leakage Crack of Adhesive and Flexible Rubber Asphalt』, analyze the problems with the current test methods in consideration of the features of materials. As a result, we assured more objective data in improved chemical resistance test methods.

• Tribology and Lubricants
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• 제12권2호
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• pp.20-31
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• 1996

Pressures in compression pockets consists of two identical spiral scrolls are influenced by gas flow resistance in discharge process and leakages in radial and tangential directions between two scroll wraps. In this paper, considering geometrical characteristics of these members, flow resistance and refrigerant gas leakage losses, pressure variations in compression pockets are calculated. For a scroll compressor model with fixed crank mechanism, acting load on crankshaft is analyzed. And, for a vertical type crankshaft-journal bearing system used in scroll compressor, nonlinear transient response is calculated including nonlinear fluid film reaction forces of journal bearings.