• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2000년도 제1회 학술대회 논문집
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• pp.185-186
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• 2000

For the quantitative investigation of the erosion of MgO layers in real ac-PDP cells, we constructed a microscopic spectrophotometer which is capable of measuring transmission spectra from the area as small as 20 ${\times}$ 20 ${\mu}m^2$. In the test on the sputtered MgO films with a thickness gradient, we were able to probe the thickness variation of 1000 nm over $1000-{\mu}m$ distance. Using this instrument, we were able to determine not only the erosion rate at the particular position of ac-PDP cells but also the relative erosion rate at different positions in a single ac-PDP cell.

• 한국정밀공학회지
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• 제18권7호
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• pp.127-133
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• 2001

The effects of triangular and rectangular discharge current waveforms on anode erosion in wire electric discharge machining is investigated based on heat transfer analysis of half-space subject to time and space-dependent heat flux. The thermal load on the anode is simulated by a hear flux that is calculated from time-dependent discharge channel radius and energy. Evolution of the melting front during discharge, the molten volume at the experimental result for qualitative verification of the analysis. It is demonstrated that the triangular current waveform is more efficient in eroding the anode than the rectangular one.

• 대한금속재료학회지
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• 제49권9호
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• pp.708-714
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• 2011

The premature failure of a servovalve used for six months in a thermal power plant has been analyzed. The servovalve was made of stainless steel, containing 16Cr-0.44Mo, along with other elements. An overload of oil-supply pumping and an abnormal increase in the oil flux were observed during operation. A study revealed that erosion and corrosion could be the main causes of the failure. The visual examination of the servovalve did not show any appreciable damage. However, corrosion and erosion of the servovalve were observed using scanning electron microscopy (SEM). Upon examination of the servovalve, the corrosion was found to have occurred throughout the bushing and spool; however, erosion occurred at only the edge-side. In addition, the condition of the electrohydraulic control system (EHC) oil was investigated with respect to its satisfaction of the management standard.

• Corrosion Science and Technology
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• 제11권3호
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• pp.89-95
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• 2012

U.S. Electric Power Research Institute (EPRI) has developed CHECWORKS program and applied it to power plant piping lines since some lines were ruptured by flow-accelerated corrosion (FAC) in 1978. Nowadays the CHECWORKS program has been used to manage pipe wall thinning phenomena caused by FAC. However, various erosion mechanisms can occur in carbon-steel piping. Most common forms of erosion are cavitation, flashing, liquid droplet impingement erosion (LDIE), and Solid Particle Erosion (SPE). Those erosion mechanisms cause pipe wall thinning, leaking, rupturing, and even result in unplanned shutdowns of utilities. Especially, in two phase condition, LDIE damages a wide scope of plant pipelines. Furthermore, LDIE is the major culprit to cause such as power runback by pipe leaking. This paper describes the methodologies that manage wall thinning and also predict LDIE wall thinning area. For this study, current properties of two-phase condition are investigated and LDIE areas are selected. The areas are checked by B-Scan method to detect the effect of wall thinning phenomena.

• Corrosion Science and Technology
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• 제19권5호
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• pp.239-249
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• 2020

The characteristics of cavitation-erosion damage with changes in the amplitude of 5052-O aluminum alloy for ships were investigated in a seawater environment. In the cavitation-erosion experiment, the cavitation environment was created using a vibration-generating device with a piezo-electric effect. The amplitudes of 5 ㎛, 10 ㎛, and 30 ㎛ were created by changing the geometric shape of the cavitation horn. The resistance characteristics of cavitation-erosion damage were evaluated by weight loss and pitting area. The damaged surface was analyzed using scanning electron microscopy (SEM) and 3D optical microscopy. As the amplitude increased, the amount of damage and the area of the damaged surface increased, and the damage was concentrated at the center and edge of the specimen. The pit was created after the initial incubation period with increasing experimental time, and then the pits were merged to grow and propagate into craters, and eventually, the surface was detached and damaged. The cavitation-erosion damage after 30 minutes with amplitude of 10 ㎛ and 30 ㎛ was 1.48 and 2.21 times compared to 5 ㎛, respectively.

• Journal of Advanced Marine Engineering and Technology
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• 제28권2호
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• pp.332-337
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• 2004

The use of gas absorption refrigeration machine has considerably increased because of the shortage of the electric power in the summer and the regulation of freon refrigerant. Gas absorption refrigeration machine consists of a condenser, a heat exchanger. supplying pipes, a radiator etc, This system is likely to be corroded by acid. dissolved oxygen and gases, Cavitation erosion-corrosion by flow velocity of cooling water may happen in absorption refrigeration machine. In these cases. erosion and corrosion occur simultaneously. Then, it makes a serious damage with synergy effect. Therefore, this paper was studied on the cavitation damage of cupronickel(70/30) tube for gas absorption refrigeration machine, In the $30^{\circ}C$ tap water, linear polarization test and anodic polarization test were carried out for copper(C1220T-OL) and cupronickel(70/30) tube. Also, cavitation erosion-corrosion behavior of cupronickel (70/30) tube was considered, The main results are as following: (1) In the linear test, the corrosion current density of cupronickel(70/30) is higher than that of copper. (2) The erosion-corrosion rate of cupronickel(70/30) displayed later tendency than that of copper by vibratory cavitation in cooling water. (3) In cooling water, the progress mechanism of erosion-corrosion rate of copper and cupronickel(70/30) follows a pattern of incubation, acceleration, attenuation and a steady state period.

• 한국전기전자재료학회논문지
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• 제29권5호
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• pp.307-311
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• 2016

Although there are existing Residual Current Protective Device (RCD) including detect electric leakage and elements such as short circuit and surge, the occurrence of incidents caused by electric faults, including fire, are still constant. The purpose of this study is to analyze the causes of accidents through the electric field distribution in the interpretation of the fault contact breaker. Simulation results by the arc fault has shown the convergence of temperature and electric field to the defect. Through their simulation results, the main cause of erosion phenomena in circuit breaker bar is the electric arc by concentration of electric field not due to dissolve by temperature.

• 조명전기설비학회논문지
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• 제24권8호
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• pp.78-83
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• 2010

본 논문은 배전선으로 널리 사용되고 있는 비닐캡타이어 타원형코드(Polyvinyl chloride insulated cabtyre oval cord, VCTFK)의 끝단에서 발생되는 트래킹의 진전특성에 대하여 언급하고 있다. 트래킹은 VCTFK의 끝단에 전해액을 적하함으로써 발생시켰다. VCTFK 끝단에서 발생되는 트래킹 진전과정 및 그 특징은 다음과 같다. 방전으로 인해 VCTFK 끝단에서 탄화가 시작되었고 침식도 일어났다. 도체에서 가까운 절연층이 먼저 침식되었으며, 피복층은 그 이후에 침식되었다. 침식이 진행된 이후, VCTFK 끝단의 표면에서 탄화물의 적층이 시작되었다. 적층 단계에서 아크를 동반했으며, 트래킹 파괴로 이어졌다.

• 기술사
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• 제34권5호
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• pp.40-43
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• 2001

상암동 월드컵 주정기장은 축구 전용경기장으로서 2002년 월드컵 축구경기를 위한 꿈과 감동의 라이브 스테이지로서의 스타디움 시설로 각종 국내외 축구경기는 물론 문화행사를 효율적으로 운영할 수 있도록 계획되었다. 이에 효율적인 경기장 시스템 구성과 적정한 전기시설물 설치로 최상의 경기운영을 할 수 있도록 전력시스템을 안정화 하였으며, 월드컵 경기 이후 스포츠공간과 상업시설, 공공시설 등 복합화된 스포츠 문화시설에 부합할 수 있도록 수변전 설비 및 방재센타 등을 다분화하여 시설하였으며 국제적 행사의 장에 전기인으로서 일익을 담당할 수 있었음에 감사한 마음이다.

• 한국산림과학회지
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• 제102권4호
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• pp.571-577
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• 2013

이 연구는 계류에 설치되어 있는 사방공작물이 계류수질에 미치는 영향을 구명함으로써 계류복원을 위한 사방공작물의 설치방향을 정립하기 위한 기초자료를 제공하기 위하여 수행하였다. 북한산 우이동 계곡에서 사방공작물이 설치되어 있지 않은 상류지역의 평균pH는 6.32(5.73~6.90)로 사방공작물을 통과한 계류인 하류지역의 평균pH[6.53(6.25~6.82)]와 유사하였으며, 상류지역에서의 평균용존산소량은 10.3(9.6~10.6) mg/L로 사방공작물을 통과한 하류지역에서의 평균용존산소량 10.2(9.9~10.4) mg/L와 유사하였다. 평균전기전도도는 상류지역에서는 $62.2(40.3{\sim}89.5){\mu}S/cm$, 하류지역에서는 $63.9(32.6{\sim}120.4){\mu}S/cm$로 유사하였고, 평균음이온총량은 상류지역에서 4.51(2.56~4.29) mg/L, 하류지역에서 5.94(3.43~7.98) mg/L로 유사하였다. 산청군 홍계계곡에서 평균pH는 상류지점에서 6.89(6.61~7.12), 하류지점에서 6.86(6.50~7.10)으로 유사한 값을 나타내었고, 평균용존산소량은 상류지점에서 12.2(11.6~12.6) mg/L, 하류지점에서 11.9(11.5~12.3) mg/L로 유사하였다. 평균전기전도도는 상류지점에서 $32.7(31.4{\sim}34.3){\mu}S/cm$, 하류지점에서 $33.4(31.6{\sim}34.6){\mu}S/cm$로 유사하였고, 평균음이온총량은 상류와 하류지점에서 1.0(0.1~2.2) mg/L로 매우 유사한 값을 나타내었다. 북한산 우이동계곡과 산청군 홍계계곡을 대상으로 사방공작물이 설치되어 있지 않는 자연계류와 사방공작물이 설치된 하류지역에서의 계류수질을 분석한 결과 상하류간의 수질은 큰 차이가 나타나지 않았다. 사방공작물은 시공과정에서 계류수질에 영향을 미치므로 계류복원을 위하여는 각 개별 사방공작물에 대하여 시공 전후의 계류수질변화과정을 시계열적으로 심도 있게 연구할 필요가 있다.