• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 하계학술대회 논문집 Vol.5 No.2
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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.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 A
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• pp.277-280
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• 1999

We fabricated a resistive superconducting fault current limiter of two stripe meander type based on a YBCO film, and performed current limitation experiments. In order to disperse the heat generated at hot spots in the YBCO film the film was coated with a gold shunt layer. At $0^{\circ}$ fault angle the minimum quench current was $9.6 A_{peak}$(meander line cross section: $5{\times}10^{-6}cm^2$) and the fast quench time was 0.63 msec. The resistance of the limiter continued to increase for three cycles due to heat generation in the gold layer and was stabilized afterwards. At $45^{\circ}$ and $90^{\circ}$ the fast quench time were 0.56 msec and 0.26 msec, respectively. The quench time is believed to be reduced because faults occurred when the current was increasing or was at the peak value. With the limiter we could effectively limit the fault current about 1/5 times right after the fault and about 1/8.5 times three cycles after.

• 전력전자학회논문지
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• 제10권6호
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• pp.618-625
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• 2005

본 논문은 CRT 표시장치에서 고전류밀도를 구현하기 위한 전자총의 히터와 캐소드의 최적의 저전력설계와 실험을 수행하였다. CRT 표시장치에서 밝기, 고휘도, 고해상도와 대화면화를 위해서는 전자총 캐소드(cathode)의 고전류밀도가 필수적이다. 이를 위해서는 함침형 캐소드가 사용되며, 고전류밀도를 얻기 위해 히터의 동작온도를 높여야하는데 이에 비례하여 소비전력도 증가한다. 본 논문에서는 고전류밀도 캐소드 히터의 저전력 설계를 위하여 히터의 리드형태(Lead Type), 코팅(Coating)법, 발열부의 1차 및 2차 코일링의 피치와 권선수를 달리한 샘플을 제작, 시험하였다.

• 열처리공학회지
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• 제32권5호
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• pp.224-229
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• 2019

PVD coating is a technology that can be applied to various industries, and is widely used for processing molds and machinery, improving performance of core parts, and extending the life. Therefore, there is a need for a research on a device and a process technology that can adjust the performance to suit each application. In this study, a PVD coating device with ion density control was used to deposit a coating layer on SKD 11, a cold die steel, with magnetron currents of 1 A, 2 A, 3 A at arc currents of 80 A, 100 A, 130 A. It examined the mechanical properties for each condition. Increasing the arc current and magnetron current could improve the thickness, adhesion, and hardness of the coating layer. Especially, When the magnetron current was high, it suppressed the droplets that could be generated by the high arc current, showing excellent surface uniformity and adhesion of the coating layer.

• 동력기계공학회지
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• 제20권5호
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• pp.29-36
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• 2016

Aluminum alloys have been widely used in engine materials, cold & hot-water storage vessels and piping etc., Furthermore, the aluminum alloy of AC8A have been widely used in mold casting material of engine piston for various vehicles because of its properties of temperature, wear and corrosion resistance. Therefore, it is considered that evaluation of corrosion resistance as well as wear resistance of AC8A material is also important to improve its property and to prolong its lifetime. In previous paper, the effect of solution($510^{\circ}C$:4hrs) and tempering($190^{\circ}C$: 16, 24, and 36 hrs)heat treatments to corrosion resistance and hardness were investigated using electrochemical method. In this study, in order to examine completely the effect of the tempering hours to hardness variation and corrosion resistance, the results of solution($510^{\circ}C$:4hrs) and tempering($190^{\circ}C$: 2, 4, 8 and 12hrs)heat treatments to hardness and corrosion resistance were investigated using electrochemical method. The hardness decreased with solution heat treatment compared to mold casting condition, but its value increased with tempering heat treatment. Furthermore, the corrosion resistance increased with decreasing of the hardness, and decreased with increasing of the hardness reversely. And the tempering heat treatment temperature at $190^{\circ}C$ for 8 hrs exhibited the highest value of the hardness and also indicated the highest corrosion current density. However, the values of hardness and corrosion current density was again increasingly decreased with increasing of tempering hours than 8 hrs, Consequently, it is suggested that decision of the optimum. tempering hours is very important to improve the corrosion or wear resistance.

• 한국구조물진단유지관리공학회 논문집
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• 제16권2호
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• pp.40-48
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• 2012

콘크리트내의 철근의 부식은 열화와 콘크리트 구조물의 조기파괴의 주된 원인이 된다. 본 연구에서는 비파괴 기법 중 전자기적 열유도방법과 적외선 열화상기법을 이용한 철근부식평가가 시도되었는데, 부식 또는 비부식된 철근의 열특성 차이를 이용한 것이다. 본 논문은 이러한 개념을 배경으로 수행한 실험적 연구이며, 유도전류를 통해 콘크리트 표면으로부터 내부 철근을 가열하고 외부의 적외선 카메라를 이용하여 표면의 온도변화를 관측한다. 피복두께가 다른 콘크리트 시편은 앞면과 배면의 피복두께를 동일하게 제조하여 앞면에서 가열과 배면에서의 온도측정을 동시에 할 수 있도록 고안되었다. IC (Impressed Current) 방법을 통하여, 철근 부식을 촉진하였으며, 적외선 화상을 통하여 온도가열과 냉각을 전 시험과정에 걸쳐 측정하였다. 본 실험을 통하여 부식/비부식 철근의 뚜렷한 온도변화를 확인하였으며, 부식된 시편에서 빠른 온도증가속도 및 냉각속도를 평가하였다. 본 연구는 콘크리트 매립철근의 비파괴적인 부식탐지의 가능성을 보여주고 있다.

• Journal of Welding and Joining
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• 제14권5호
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• pp.113-121
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• 1996

The arc sensor has been most widely used for weld seam tracking through welding current or voltage variation. In this work, the relation between the arc light intensity and welding condition is investigated using heat balance in the Plasma for its possible application to seam tracking in the GMAW process. The arc light intensity is derived to be the function of the arc length and welding current Experiments are carried out to verify the proposed heat balance model. Performances of least square and integration methods to process the signals for seam tracking are compared experimentally. Predicted arc light intensity shows reasonably good agreement with experimental results. The weld seam is successfully tracked through the arc light intensity. The least square and integration methods demonstrate almost same performance of seam tracking with $CO_2$gas shielding.

• 한국초전도ㆍ저온공학회논문지
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• 제6권1호
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• pp.1-5
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• 2004

Long length of Bi-2223/Ag superconducting wives were fabricated by stacking and drawing process with advanced heat-treatment schedules. Intermediate annealing was carried out to increase the homogeneity and uniformity of the superconducting filaments embedded in the silver matrix. Phase modification from tetragonal to orthorhombic Bi-2212 by pre heat treatment(PHT) was executed to improve the texture and phase transformation of Bi-2223. Drawing stress was measured to predict the sausaging and stress limit. Rolling Parameters such as thickness. width and winding tension were investigated to roll the tape with uniformity. 1 km length of Bi-2223/Ag superconducting wires were fabricated without any breakage. Critical current (Je) of 270 m length of superconducting tapes was measured over than $70 A/cm^2$ continuously after final sintering.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.1699-1704
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• 2005

In this research the energy degrader, which is the most fragile part of the security of a target, has been newly designed to improve the performance of the gas target. Also, the numerical analysis of the heat movement and mechanical movement during the operation of the target has been accomplished. The heat analysis and structure analysis which are using the cooling water flow and pressure in the energy degrader and the Nastran mediocrity finite element analysis program, has been considered with the heat movement and mechanical movement according to the current capacity of proton beam which determines the production yield of the radioactive isotope. Also the possible use range has been determined, and at the same time the most suitable running condition according to the current capacity of proton beam has been suggested.

• 한국전기전자재료학회논문지
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• 제31권2호
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• pp.107-111
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• 2018

In this study, we designed the temperature coefficient of resistance (TCR) and heat radiation properties of shunt fixed resistors by adjusting the atomic composition of a metal alloy resistor, and fabricated a resistor that satisfied the designed properties. Resistors with similar atomic composition of copper and nickel showed low TCR and excellent shunt fixed resistor properties such as short-time overload, rated load, humidity load, and high temperature load. Finally, we expect that improved sensor accuracy will be obtained in current-distribution-type shunt fixed resistor for IoT sensors by designing the atomic composition of the metal alloy resistor proposed in this work.