• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 C
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• pp.1781-1783
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• 1996

Recently, the necessity of establishing the way to diagnose the aging of insulation materials and to predict of insulation breakdown become important. The purpose of our work are to investigate the treeing phenomena with a artificial needle shape void by the charge of partial discharge and acoustic emission pulse in each phase angle area at the same time. We have analyzed the ${\Phi}-Q-n$ pattern and the insulation diagnosis of the samples using statistic operators such as charge magnitude and A.E pulse factor, skweness, kurtosis, G,C. Therefore, the relation between the charge of partial discharge and A.E pulse will be helpful and efficient to predict the breakdown just before the breakdown occure.

• Journal of Mechanical Science and Technology
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• 제14권7호
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• pp.773-781
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• 2000

The focus of this study is the development of a credible fault detection system of the cylindrical plunge grinding process. The acoustic emission (AE) signals generated during machining were analyzed to determine the relationship between grinding-related faults and characteristics of changes in signals. Furthermore, a neural network, which has excellent ability in pattern classification, was applied to the diagnosis system. The neural network was optimized with a momentum coefficient, a learning rate, and a structure of the hidden layer in the iterative learning process. The success rates of fault detection were verified.

• 한국환경과학회지
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• 제8권1호
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• pp.135-144
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• 1999

Air quality modeling about coastal urban region such as Pusan shoud be consider shipping source emmited from ships anchoraging and running. It has been proved at our previous studies that the ratios of air pollutants emission amount in coastal area to inland are 12.2% for NO$_2$ and 11.7% for $SO_2$ and the air qualify of coastal urban area consierably counts on ships. Also the dispersion pattern of the all pollutants followed local circulation system in this region. Therefore this study has been developed air quality model which can describe the formation, transport, transformation and deposition processes of air pollutants considering shipping source. Currently, restriction for emission amount of ships does not exist, so our study will be useful to set the omission standard and for devising air quality policy in coastal urban region.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1998년도 춘계학술대회 논문집
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• pp.223-226
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• 1998

In this paper, we have investigated how morphology and electrical properties in Polyphenylene sulfide(PPS) are changed by uniaxial elongation. XRD pattern shows that interplanar distance and crystallinities are decreased by increasing elongation ratio. Electrical conduction mechanism of PPS is explained as schottky emission from analysis of electrical current. The electrical current is decreased by increasing elongation ratio. The conductivity is changed remarkably above the glass transition temperature around $(82^{\circ}C)$. The band gap of PPS is evaluated as 3.9-4(eV) from the results of photoconductivity. Increarnent of elongation ratio gives us some information about deep trap formation from photocurrent.

• 한국전기전자재료학회논문지
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• 제11권10호
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• pp.763-767
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• 1998

In this paper, it is investigated how the morphology and electrical properties in Polyphenylene Sulfide(PPS) changed by uniaxial elongation. XRD(X-ray diffraction) pattern shows that interplanar distance and crystallinities are decreased by increasing elongation ratio. electrical conduction mechanism of PPS is explained as Schottky emission mechanism. the electrical current is decreased by increasing elongation ratio. The conductivity is changed considerably above the glass transition temperature around 82(>$^{\circ}C$). The band gap of PPS is evaluated as 3.7~4(eV)

• Journal of the Optical Society of Korea
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• 제6권3호
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• pp.83-86
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• 2002

Nanoscopic emission from periodic nano-hole arrays in thick metal films is studied experimentally. The experiments give direct evidence for SP excitations in such structures. We show that the symmetry of the emission is governed by polarization and its shape is defined the interference of SP waves of different diffraction orders. Near-Held pattern analysis combined with the far-Held reflection and transmission measurements suggests that the SP eigenmodes of these arrays may be understood as those of ionic plasmon molecules.

• 한국자동차공학회논문집
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• 제11권1호
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• pp.18-24
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• 2003

Vehicle emission is one of the major sources of air pollution, and provides some undesirable effects on the atmospheric environment and human health. In this study, the driving data were recorded during road tests in Seoul metropolitan wet and analyzed by statistical techniques. The objective of the study is to analyze the driving Patterns of passenger car that influence on emissions in urban driving. The results show that the average speed is around 29.2 km/h, and the average fuel economy is 10.23 km/$\ell$. The vehicle speed of Seoul metropolitan area is slower, and the stop-and-go operation is more frequent than CVS-75 test mode which is used far emission and fuel economy test.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 제6회 학술대회 논문집 일렉트렛트 및 응용기술연구회
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• pp.52-56
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• 2004

The movement of electron in the semiconductor-gap-semiconductor was observed by the variation of V-I characteristic as a distance two ZnO(1010) single crystals. When the resistance between two crystals was $10^2{\sim}10^4{\Omega}$, V-I characteristics had the pattern of the field emission or ohmic contact. On the other hand, when the resistance was larger than $10^7{\Omega}$ by increasing the distance between two crystals, the effect of surface barrier was prominent. This result leads to the conclusion that both the field emission (or ohmic contact) and the surface barrier effect including the tunneling have the influence on V-I characteristics of mechanically contacted crystals.

• 분석과학
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• 제14권4호
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• pp.311-316
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• 2001

본 연구는 한약재 중 우리 나라의 여러 지역에서 재배되고 있는 황기를 선택하여 유도결합 플라스마 분광분석법(inductively coupled plasma-atomic emission spectroscopy ; ICP-AES)을 이용한 미량성분을 분석하여 principal component analysis(PCA)와 pattern recognition의 원리를 이용한 chemometrics Analysis로 한약재에 함유된 미량 금속 성분 함량에 의한 원산지 판별의 가능성을 조사하였다. 황기와 토양시료는 각각 $HNO_3$와 $H_2O_2$ 그리고 $HNO_3$와 HCl를 첨가하여 microwave oven을 사용하여 전처리 하였다. ICP-AES를 사용하여 황기와 황기를 재배한 토양 속에 들어 있는 미량 금속 성분으로는 Mg, Al, K, Ca, Ti, Mn, Fe, Cu, Zn, and Ba 등이 있으며 그 중 Al과 Fe 그리고 Zn과 Ti의 함량으로는 PCA와 pattern recognition을 이용하여 각 재백지의 황기와 토양간의 연계성을 살펴보았다. 그 결과 국내산 황기와 중국산 황기를 PCA 방법으로 원산지 판별이 가능하였으며 구례, 예천, 제천, 그리고 정선의 국내산 황기의 원산지 판별이 가능하였다.

• 비파괴검사학회지
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• 제15권4호
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• pp.520-530
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• 1996

본 연구에서는 음향방출법을 이용하여 로터리 압축기의 인공 결함을 분류하기 위한 연구를 수행하였다. 이를 위해 프로그램을 개발하였고 선형 분류기, 경험적 Bayesian 분류기, 신경 회로망 분류기를 함께 사용하여 비교하였다. 그 결과 신경 회로망 분류기가 인식률 면에서 유리하였으며 신경 회로망 분류기의 경우 99%이상의 인식률을 얻을 수 있었다.