• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.04a
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• pp.55-56
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• 2008

The photo leakage currents of a conventional hydrogenated amorphous silicon(a-Si:H) thin film transistor(TFT) were investigated and analyzed in the case of illumination from various lightsources such as halogen lamp, cold cathode fluorescent lamp(CCFL) backlight, and white light emitting diode(LED) backlight The photo leakage characteristics showed the apparent differences in the leakage level and in the $I_{on}/I_{off}$ ratio in spite of the similar luminances of light sources. This leakage level is expected to be related to the wavelength of the lowest intensity peak from spectral analysis of light sources.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.11
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• pp.908-913
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• 2000

CoSi$_2$/p+/n diodes(bilayer diodes) were fabricated by using epitaxial CoSi$_2$grown from Co/Ti bilayer as a diffusion source. The I-V characteristics of p+/n diodes were measured and compared with those of diode made from Co monolayer (monolayer diode). Monolayer diodes showed typical p+n junction characteristics with the leakage current of as low as 10$^{-12}$ A and forward current 6-orders higher than the leakage current, when drive-in annealed at 90$0^{\circ}C$ for 20 sec.. On the other hand, bilayer diodes showed the Schottky-like behaviors with forward currents rather higher than those of monolyer diodes, but with too high leakage currents, when drive-in annealed at $700^{\circ}C$ or higher. However, when the annealing temperature was lowered to $700^{\circ}C$ and annealing time was increased to 60 sec., the leakage current was reduced to 10$^{-11}$ A and thus sho3wed typical diode characteristics. The high leakage currents for diodes annealed at $700^{\circ}C$ or higher was attributed to Shannon contacts formed due to unremoved Co-Ti-Si precipitates. But when annealed at 50$0^{\circ}C$, B ions diffused in the direction of the surface layer, and thus the leakage currents were reduced by removing Shannon contacts.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.1
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• pp.37-45
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• 2012

This study investigates the pressure leakage characteristics of a desiccant rotor with a brush-type air seal. Through a pressure leakage experiment, a correlation equation for the leakage air flow rate is obtained as a function of the air seal area and pressure difference. Using this equation, an air leakage model for the desiccant rotor is developed. By comparing simulation results with the experimental results for the desiccant rotor, the accuracy of the air leakage model is demonstrated. A performance test of a desiccant rotor with various air flow rates is carried out. Using the air leakage model, the effective mass flow rate and air leakage rate are found. In addition, the characteristics of the air leakage are analyzed for a desiccant cooling system using the developed air leakage model.

• 전기의세계
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• v.25 no.4
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• pp.59-62
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• 1976

This study on the characteristics of the leakage circuit breakers handles the rolls of each itemized parts of the mentioned apparatus and their influence in determining of the characteristic curve of leakage circuit breaker. Furthermore the differential current transforms in the mentioned apparatus for detecting the fault is handled as a heavy point.

• Tribology and Lubricants
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• v.20 no.4
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• pp.204-208
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• 2004

This paper presents the oil leakage characteristics of the valve stem system in gasoline engines. For the oil leakage investigation, four study models have been prepared as functions of used poppet valve and used valve stem seal, used poppet valve and unused valve stem seal, unused poppet valve and used valve stem seal, and unused poppet valve and unused valve stem seal. With four models, the experimental study on the oil leakage has been investigated for the oil temperature, intake pressure, and camshaft speed. The experimental results show that the sealing performance of the valve stem seal plays an important role on the leakage of the valve stem system. And the appropriate replacement of a stem seal with used poppet valve shows good sealing performance in oil leakage in compared with a new valve system.

• The KSFM Journal of Fluid Machinery
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• v.14 no.4
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• pp.57-63
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• 2011

Regenerative blower is suitable for hydrogen recirculation in fuel cell vehicle due to its capability of high pressure rise in single stage. Numerical models were applied to investigate inner gap leakage flow characteristics. A leakage flow in the inner gap is dominantly affected by pressure gradient. Therefore a blower with concentric channel type was suggested as one of modified models for reducing the inner gap pressure gradient. Also numerical results such as pressure rise, efficiency, leakage flow rate and torque were compared between modified and reference models. The performance of concentric channel type was improved as a result of reduced leakage flow.

• Tribology and Lubricants
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• v.13 no.3
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• pp.56-62
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• 1997

Sealing an oil-air mixture plays important roles to have an enhanced lubrication for high speed spindle. High speed spindles require non-contact type sealing mechanism. In this study, an optimum seal design to minimize leakage is concerned in the aspect of flow control. This paper categorizes geometries of mostly used non-contact type seals and analyzes each leakage characteristics to minimize a leakage on sealing area. Effect of minimum clearance and its position are considered according to variation of detail geometry. The estimation of non-leaking property is determined by amount of pressure drop in the leakage path assuming constant leakage flow. 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. Design parameters has been induced to minimize leakage in limited space, and a methodological study on geometrical optimization has been conducted.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07b
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• pp.1125-1128
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• 2004

This paper presents the temperature characteristics with structure of 18 kV lightning arresters for distribution. Three types of polymer arresters were fabricated and ceramic type arrester was also ready to investigate. Below $100^{\circ}C$, three types of polymer arresters exhibited almost the same leakage current value, but above $100^{\circ}C$, polymer arrester that arrester module was injected into polymer housing with grease exhibited the highest leakage current and the arrester with the lowest leakage current was the arrester that silicon rubber was directly injected to arrester module. The rising of leakage current of polymer arrester with grease was because of existing grease between FRP winding and silicon housing, and reducing the insulation characteristics of the grease. All polymer arresters exhibited the same temperature characteristics but ceramic typr arrester was slower than polymer arrester in heat emission despite lowest leakage current. It was thought that the air layer between ZnO varistor blocks and ceramic housing prevented the heat emission. However, in spite of the difference of the structure, the variation of the surface temperature of all arresters exhibited the same result.

• Journal of Power Electronics
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• v.15 no.1
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• pp.256-267
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• 2015

Grid-connected transformerless photovoltaic (PV) inverters (TPVIs) are increasingly dominating the market due to their higher efficiency, lower cost, lighter weight, and reduced size when compared to their transformer based counterparts. However, due to the lack of galvanic isolation in the low voltage grid interconnections of these inverters, the PV systems become vulnerable to leakage currents flowing through the grounded star point of the distribution transformer, the earth, and the distributed parasitic capacitance of the PV modules. These leakage currents are prohibitive, since they constitute an issue for safety, reliability, protection coordination, electromagnetic compatibility, and module lifetime. This paper investigates a wide range of multi-kW range power rating TPVI topologies and classifies them in terms of their leakage current attributes. This systematic classification places most topologies under a small number of classes with basic leakage current attributes. Thus, understanding and evaluating these topologies becomes an easy task. In addition, based on these observations, new topologies with reduced leakage current characteristics are proposed in this paper. Furthermore, the important efficiency and cost determining characteristics of converters are studied to allow design engineers to include cost and efficiency as deciding factors in selecting a converter topology for PV applications.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.10b
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• pp.421-422
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• 2002

The purpose of this paper is to investigate the leakage characteristics of the valve stem in the gasoline engines. Especially, three factors affecting oil leakage are the power cylinder, engine head system, and the positive crankcase ventilation system. Which is the most variables, analysis difficulty is the valve stem seal characteristics. The testing system is used with oil motoring system. The leakage of an engine is analyzed for the cylinder temperature, atmosphere pressure, positive pressure, negative pressure, revolution of the camshaft and the surface roughness of the valve stem.