• Transactions of the Korean Society of Mechanical Engineers A
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• v.32 no.7
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• pp.541-548
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• 2008

To improve the operational stability of the 100 Watts class Micro Gas Turbine, the air foil bearing with additional damping material has been investigated. The key of structure is that a viscoelastic material is coated under the top foil. The compliant foil journal bearing and thrust bearing are designed to withstand high load of vibrations at the operational speed 870,000 rpm. Test is executed in room temperature. Rotor has stably operated above 480,000 rpm. It is over 55% of the designed speed 870,000 rpm. Synchronous and subsynchronous vibrations are both well controlled. Vibration amplitude diminished over 50%. With the help of increased damping resulting from the viscoelasticity, the rotor stability of Micro turbocharger has been improved.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.20 no.4
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• pp.490-494
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• 2011

In this paper, using by rapid heating and cooling systems for injection molding and temperatures to changes. In the process of molding temperature and pressure inside the mold was found. In addition, the tensile strength of test specimens were molded, mechanical properties of injection molded parts were identified on mold temperature. Copper could withstand more tensile force than NAK. Therefore, it can be concluded that materials with high heat conductivity must be used in thin walled products.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.10a
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• pp.523-528
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• 2000

In multi-span bridges, a shear key is often used to distribute the seismic force to the case, the shear key is sometimes required to be reinforced to withstand the seismic force. To improve the strength of shear key, the strength and failure mode of shear key have to be carefully estimated and the proper reinforcement scheme should be elaborated. The test results show that the strength of shear key is 2.5 times higher than the strength calculated by PCI design handbook. Also the strength of shear key is greatly improved by placing PT bars into shear key. In this study, the analytical method to evaluate the strength of sheat key and the reinforcement scheme are proposed.

• Proceedings of the KIEE Conference
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• 1999.11d
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• pp.1105-1107
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• 1999

The purpose of termination for high voltage tests of XLPE power cable is to prevent flashover during the breakdown test of specimen as well as to withstand the specified voltage between its conductor and screen without failure. For easier treatment and simpler construction of testing termination, resistivity grading method using semi-conductive material was employed. Based on the fundamental theory, its failure characteristics by changing the resistivity of semi-conductive material on the insulation surface was investigated. With two layers construction by difference resistivity on their surfaces, much improved result than that of one resistivity was obtained through the experiment for MV cable.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2002.05a
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• pp.98-102
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• 2002

As the nuclear power plant has been operated continuously and increased gradually, transportation and storage of spent fuel are seriously considered nowadays. The transportation cask which contains radioactive material needs to be inspected about structural safety. About safety verification, description of IAEA Safety Standards states that cask must withstand hypothetical accident conditions. In this paper, 9m free drop impact analysis was performed for transportation cask and impact limiter by using the finite element methods. Furthermore, we obtained the dynamic behavior of wood to as compared with safety test results, and verified the safety of transportation cask.

• 전기의세계
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• v.18 no.2
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• pp.7-14
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• 1969

From the first customer located right at the substation to the last customer at the end of the line, voltage must be held within close limits, so the voltage regulation is more important than the thermal limit. On a typical distribution system during the peak load period, the voltage drop may be serious enough to cause unsatisfactory operation of home appliances in the residential area, and present many problems to manufacturing industries, where the voltage must be maintained within close limits to insure smooth operation. Among all the factors contributing to voltage drop in the distribution system, the voltage drop in the distribution transformer may account for 30% of this figure. If we can eliminate this factor, the power companies can provide better quality electricity to more customers with the existing distribution facilities, thus saving on initial investment costs. Taking all these problems into consideration, the author undertook the design of a capacitive transformer which would give zero voltage drop at rated load and at 80% lagging power factor while incorporating overload features to withstand 400% overload for at least 100 seconds. The following are the results obtained through design, manufacture and test of an initial experimental transformer built with these specific purposes.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.04a
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• pp.163-167
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• 2007

Silver is widely used for catalytic decomposition of hydrogen peroxide, but start-up at room temperature is difficult and cannot withstand at high temperature. In this paper, to overcome these short-comings, a dual catalytic bed which consists of a vaporizer catalyst and a high temperature catalyst was studied. Platinum was selected as the vaporizer catalyst and perovskite type catalyst was selected for the high temperature catalyst. Preliminary test demonstrated start-up capability with non-preheating at room temperature and good thermal stability at high temperature.

• Proceedings of the KIEE Conference
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• 1994.07b
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• pp.1633-1635
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• 1994

This paper presents the development technology of standard resistor divider for full lightning impulse voltage. The ability of high voltage bulk power equipment to withstand lighting stroke is usually evaluated by means of full lightning impulse voltage. Lightning impulse voltage test has been essential to evaluate the insulation performance of electrical power apparatus. Recently International standard (IEC 60) on high voltage measurement techniques is being revised and requests a formal traceability of high voltage measurements. Therefore, general interest for this area has grown considerably during last years, and several international intercomparisions have been completed already worldwide, i.e. Europe, Japan, America etc.. In this viewpoint, we have also investigated the standard resistor divider with shield, which satisfies the IEC recommendation.

• Proceedings of the KIEE Conference
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• 2000.07c
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• pp.1843-1845
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• 2000

GIS(Gas insulated switchgear)내부에서 발생한 부분방전 신호를 검출 할 수 있는 UHF(Ultra-high frequency) 부분방전 검출 센서를 345 kV GIS의 AC 내전압 시험에 적용하였다. 부분방전 센서를 적용한 상태에서 각 상별로, bus별로 나누어 계통 최고전압의 1.0 p.u, 1.5 p.u, 1.73 p.u 전압을 단계적으로 인가하였으며 간헐적으로 부분방전 신호가 검출됨을 확인하였다. 간헐적인 부분방전 신호는 GIS 내부에 있던 이물질에서 약한 방전이 시작되고 인가전압을 높임에 따라 방전의 강도가 증가하다 소멸되었다. 방전을 일으킨 이물질이 모두 증발되었거나 위치 변화에 의해 방전이 소멸된 것으로 판단된다.

• Proceedings of the KIEE Conference
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• 2000.07c
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• pp.1894-1896
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• 2000

A Study on TOID system which can measure a degree of diagnosis oil Tr. TOID system uses porous ceramic sensor and accept a DC 2000V, this method is to accumulate carbon element generated from the both electrodes from the ingredients the sensor when being vaporized the oil. The main substance of our research were comparison between vaporizing detection result of the oil, gas analysis, withstand voltage, test of acid value, and to define a new technology of measurement.