• 조명전기설비학회논문지
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• 제18권1호
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• pp.73-77
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• 2004

전력 시스템의 오손에 의한 사고 방지를 위한 가장 효과적인 방법은 오손도를 정확하게 예측하는 것이다. 전력시스템은 옥외에 노출되어 있으므로 오손 및 열화가 불가피하며, 오손의 증가는 사고의 위험성을 악화시킨다. 한편, 오손의 주요소는 염분이며, 오손도는 등가 염분 부착 밀도(ESDD)로서 나타낼 수 있다. 기후 조건은 지속적으로 오손도를 증감시키고 있다. 기후와 오손도의 상관관계를 해석하여 오손도를 예측할 수 있으며, 다중 회귀 분석방법를 통하여 분석이 가능하다. 이와 관련된 선행연구에서는 높은 신뢰도를 확인할 수 있었다(0.874). 그러나 이러한 방법은 다른 시기에 적용한 경우 상관성이 상당히 하강하였다. 본 연구는 이와 같은 신뢰도를 더욱 향상 시키고(0.898), 정밀한 오손도 예측을 위한 통계처리를 수행하였다.

• 한국추진공학회지
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• 제23권6호
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• pp.87-94
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• 2019

본 논문에서는 P&WC 사 PT6A-67A 엔진의 연료 필터 오염에 대한 원인 탐구를 수행했다. 관련하여 PT6A-67A 엔진 연료 필터 오염 개요와 엔진 공급라인 구성에 대해서 명시했다. 다음으로, 분석방법을 공급 연료 성분 분석과 고형 침전물 분석(EDX, TGA, 광학현미경)으로 분류하여 비교분석했다. 결과들을 종합하면, 검출된 주요 성분은 연료 탱크 실런트의 황 성분이었다. 이 결과들의 후속조치로서 P&WC와 국방과학연구소는 엔진 운용에 있어서 엔진 연료 필터 주기 점검 및 연료 탱크 세척을 수행할 예정이다.

• 대한기계학회논문집B
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• 제31권6호
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• pp.522-530
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• 2007

The practical studies on the method of particle contamination control for yield enhancement in the cleanroom were carried out. The method of the contamination control was proposed, which are composed of data collection, data analysis, improvement action, verification, and implement control. The partition check method and the composition analysis for data collection and data analysis were respectively used in the main board and the cellular phone module production lines. And these methods were evaluated by the variation of yield loss between before and after improvement action. In case that the partition check method was applied, the critical process step was selected and yield loss reduction through improvement actions was observed. While in case that the composition analysis was applied, the critical sources were selected and yield loss reduction through improvement actions was also investigated. From these results, it is concluded that the partition check and the composition analysis are effective solutions for particle contamination control in the cleanroom production lines.

• 한국재료학회지
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• 제9권5호
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• pp.491-495
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• 1999

In this study, we focus on Ca contaminant which affects on the roughness Si substrate after thermal process. The initial Si substrates were contaminated intentionally by using a standard Ca solution. The contamination levels of Ca impurity were measured by TXRF and the chemical composition of that was analyzed by AES. Then we gre the thermal oxide to investigate the effect of Ca contaminants. The microroughness of the Si surface, the thermal oxide surface, and the surface after removing the thermal oxide were measured to examine the electrical characteristics. The initial substrates that were contaminated with the standard solution of Ca exhibited the contamination levels of 10\ulcorner~10\ulcorneratoms/$\textrm{cm}^2$ which was measured by TXRF. The Ca contaminants were detected by AES and exhibited the peaks of Ca, SI, C and O.After intentional contamination, the surface microroughness of this initial substrate was increased from $1.5\AA$ to 4$\AA$ as contamination levels became higher. The microroughness of the thermal oxide surfaces of both contaminated and bare Si substrates exhibits similar values. But the microroughness of the contaminated$ Si/SiO_2$ interface was increased as contamination increased. The thermal oxide of contaminated substrate exhibited the small minority carrier diffusion length, low breakdown voltage, and slightly high leakage current.

• 한국주조공학회지
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• 제24권1호
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• pp.3-9
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• 2004

Die casting is "a process in which molten metal is injected at high velocity and pressure into a mold(die) cavity". Casting with smooth surfaces, high dimensional precision, complicated shapes, and reduced weight can be obtained using this process. But this process is susceptible to casting defects such as porosities, scattered chilled layers, hard spots, etc. For preventing casting defects, we developed "low-velocity high pressure die casting technology", "squeeze die casting technology", "heat insulating sleeve lubricant technology", and "direct pouring technology". The "direct pouring technology" is useful for producing molten metal without oxide contamination. It consists of a pumping system which supplies pure molten metal to the die casting machine. By using this technology, we have successfully reduced oxide contamination in castings to 1/20 of that of our previous castings.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.3168-3172
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• 2007

As the minimum feature size decreases, control of contamination by nanoparticles is getting more attention in semiconductor process. Cleaning technology which removes nanoparticles is essential to increase yield. A reference wafer on which particles with known size and number are deposited is needed to evaluate the cleaning process. We simulated particle trajectories in the chamber by using FLUENT and designed a particle deposition system which consists of scanning mobility particle sizer (SMPS) and deposition chamber. Charged monodisperse particles are generated using SMPS and deposited on the wafer by electrostatic force. The experimental results agreed with the simulation results well in terms of particle number and deposition area according to particle size, flow rate and deposition voltage.

• 반도체디스플레이기술학회지
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• 제6권4호
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• pp.49-52
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• 2007

As the minimum feature size decrease, control of contamination by nanoparticles is getting more attention in semiconductor process. Cleaning technology which removes nanoparticles is essential to increase yield. A reference wafer on which particles with known size and number are deposited is needed to evaluate the cleaning process. We simulated particle trajectories in the chamber by using FLUENT. Charged monodisperse particles are generated using SMPS (Scanning Mobility Particle Sizer) and deposited on the wafer by electrostatic force. The Experimental results agreed with the simulation results well. We calculate the particles loss in pipe flow theoretically and compare with the experimental results.

• 한국농공학회지
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• 제45권6호
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• pp.144-152
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• 2003

Laboratory experiments were carried out to investigate the influence of pore water contamination on the treatment effect of sandy soil which was solidified by Portland cement. In the experiments, setting time of hydraulic cement that was mixed with contaminated mixing water was measured using Vicat equipment and observed the tendency of setting process with the kind of contaminants, organic or inorganic components. It was shown that organic contaminants of the mixing water affect largely on the initial setting process of hydraulic cement and inorganics, expecially heavy metals, did not affect on the initial setting process, otherwise it was appeared that setting time of the sandy soil that was contaminated with inorganic components was apparently faster than the sandy soil that did not include inorganic components even though organic concentrations was relatively low level (COD=200∼300) in the mixing water. The results of unconfined compression strength test (UCST) were well consistent with the results of Vicat equipment test.

• 한국전기전자재료학회논문지
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• 제16권7호
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• pp.569-572
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• 2003

In this study, we evaluated the dilute HF cleaning to reduce residual defects made by metal CMP process. The purpose of this test is to observe the existence of barrier metal damage during DHF cleaning on condition that it should not affect metal thin film reliability, so we will get rid of slurry residual particles as a main defect of the metal CMP process for the better yield. In-line defect data showed us that slurry residual particles were removed by DHF application. The HF rinse significantly reduced metal contamination levels and surface roughness. The best effect by additional oxide loss was discovered when Dilute HF condition is 10".

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
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• pp.205-206
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• 2006

A ball-shape alumina arc-tube for low-wattage lamp was developed by the PIM process. An ultra high purity translucentgrade alumina powder was used. In injection molding process, a hot-runner type mold was developed. The translucent-grade alumina powder was extremely sensitive to contamination so that the injection molding condition and atmosphere control in the furnace should be taken care of with extreme caution. Contamination sources were pinpointed with EPMA. The arc-tube was molded in half and two halves were bonded in the middle by a new bonding technique at room temperature developed in this study.