• 한국광학회지
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• 제3권2호
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• pp.92-100
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• 1992

회전검광자형의 분광타원해석기를 제작하였다. 각 부품의 미소결함에 의한 오차를 고려하여 이들이 타원해석상수들에 미치는 영향을 최소로 하는 배치를 결정하였다. Straight through operation의 성능평가 결과 300nm~850nm의 파장대역에 걸쳐 tan$\psi$와 cos$\Delta$의 편차는 0.2%내외로 만족할 만한 것으로 판단되었다. SE를 사용하여 불화박막의 굴절율및 void분포상태를 측정하였고 응용성에 관하여 논의하였다.

• Tribology and Lubricants
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• 제10권1호
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• pp.78-88
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• 1994

For the study of chemical and mechanical properties of the synthetic and mineral oil added with two different Zn-DTPs, base and formulated oils were analyzed and compared. Kinematic viscosity and total acid number (TAN) were tested at high temperature for formulated oils. Also the oils added with different alkyl groups of Zn-DTP were tested for thermal stability and TAN changes. The 4-ball machine was used to test for the mechanical properties, such as the coefficient of friction and wear. The worn areas after sliding test were analyzed with microscope and EDX, too. From the study, mineral and synthetic oil have different effects according to the various added ratio of the primary and secondary alkyl groups of Zn-DTP. Also the temperature of test oil affected the anti-wear and friction property of the formulated oils. For synthetic oil, the primery alkyl group of Zn-DTP made better friction properties than that of secondary, while, for mineral oil, secondary alkyt group was better only at low temperature for mineral oil.

• 공업화학
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• 제5권4호
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• pp.722-730
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• 1994

전기절연체로 사용되는 가교폴리에틸렌(XLPE)의 내후성에 미치는 산화방지제(Antioxidant)와 카본블랙의 효과를 살펴 보았다. 산화방지제와 카본블랙을 조합하여 16가지의 시료를 제작하고 xenon-arc lamp type의 Weather-Ometer로 500, 1000, 1500, 2000 시간 촉진열화시켰을 때 촉진열화 각 시간대별로 열화거동을 관찰하였다. 인장강도, 신장율, 절연파괴전압, tan ${\delta}$로 XLPE의 내후성을 평가한 결과, 산화방지제보다는 카본블랙이 더 효과적이었고 두 첨가제를 조합해서 사용할 때 내후성이 우수한 synergistic effect를 나타냈다.

• 한국측량학회지
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• 제5권2호
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• pp.24-33
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• 1987

본 논문은 원격탐사 Data를 이용한 분야에서 보다 효과적인 좌상처리 기법 및 보다 정확한 분류화상을 얻는 것을 목적으로 하고 있다. 이의 실행을 위해 여름 좌상과 겨울 화상을 합성한 토지이용 분류결과와 여름 화상만의 분류결과를 비교분석 하였다. 위의 분석결과로부터 Bitemporal Classification 기법과 $tan^{-1}$변환이 유효함을 알아내었다. 특히 Bitemporal Classification 기법을 적용함으로써 농경지를 논과 밭으로 구별하여 분류하는 것이 보다 가능하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1987년도 정기총회 및 창립40주년기념 학술대회 학회본부
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• pp.304-306
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• 1987

The dielectric loss ($tan{\delta}$) and the Capacitance (C) of the PPMKA(plasma-polymerized methyl metacrylate) films were measured in the frequency range of 1KHz - 5MHz at $25^{\circ}C$. The effects of the oxidation and the heating and the plasma treatment for $tan{\delta}$ and C of PMMA were investigated. Dielectric loss of PPMMA films was inceased with the oxidized products like CO and OH. As condidates for their origin the existence of low molecula moieties and free radicals in the PPMMA, and the crosslinking made by the heating and plasma treatment have been considered.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 D
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• pp.2497-2499
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• 2002

This raper proposes a simple robust nonlinear controller design method based on Lyapunov stability for tracking reference welding trajectory and velocity of a three wheel welding mobile robot (WMR). Control law is obtained from Lyapunov control function to ensure asymptotical stability of the system. The effectiveness of the proposed controller is shown through simulation results.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 E
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• pp.2101-2103
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• 1999

The insulation condition of stator windings was measured by dissipation factor($tan{\delta}$) test in the six high voltage motors(rated 6.6kV) which had been in service for two years. The ${\Delta}tan{\delta}$ of motor D and E was higher than that of the rest motors. The specimens were drawn out from stator windings of the high voltage motor and their were analyzed using scanning electron microscope (SEM). SEM result shows that large voids are present in the interface both turn insulation and groundwall insulation.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1994년도 하계학술대회 논문집 C
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• pp.1265-1267
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• 1994

EPDM has excellent electric characteristics and so that it has been rapidly finding use is high voltage applications in recent years. At present EPDM is widely used for insulator of cable and accessories, and further the commercial use of Premolded housing for elbow surge arrester is started. In this paper, we have measured the temperature, pressure and voltages dependence of $tan{\delta}$ in EPDM. As a results, dielectric characteristics($tan{\delta}$) increases slightly with increasing the temperature. However, it is almost independent of the pressure and voltages.

• 한국농공학회지
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• 제42권
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• pp.68-77
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• 2000

Analyses, in which load was regarded as instant load and gradual step load, respectively, were performed with data measured on a gradually loaded field, and the results were inspected to find the effect of load conditions, and the final settlements which were predicted by Hyperbolic, Tan's, Asaoka's, and Monden's methods were compared with each other. Settlement curves in which load was regarded as instant load and gradual step load being to coincide at twice the time of duration of embankment. On the ground installed vertical drain, from the results of Hyperbolic, Tan's, Asaoka's, Monden's, Curve fitting I, and Curve fitting II (simple, carrillo) methods it was concluded that Asaoka, Curve fitting I, and Curve fitting II methods are reliable for prediction final settlement with back analysis.

• 한국정보과학회:학술대회논문집
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• 한국정보과학회 2004년도 봄 학술발표논문집 Vol.31 No.1 (A)
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• pp.91-93
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• 2004

정확한 $\pi$값의 계산은 자연과학의 여러 분야에 도움을 준다 이와 같이 $\pi$값을 계산하는 여러 가지 방법이 제안되어 있으며 널리 사용되고 있으나, 본 논문에서는 MPI 라이브러리를 활용한 $\pi$값 계산의 병렬화 알고리즘을 소개한다. tan$^{-1}$($\chi$)의 정의를 이용하는 $\pi$값 계산 방법은 다항식의 계산과정에서 각 항(term)들의 종속성으로 인하여 병렬화 수행이 힘든 단점이 있다. 본 논문에서는 tan$^{-1}$($\chi$)를 맥클로린 수열(Maclaurin Series)을 통하여 다항함수로 표현하고, 병렬화 수행에 적합한 적분형태로 변형한다. 따라서. MPI 환경에서 수행하기 적합한 $\pi$값 계산의 병렬화 알고리즘을 제안하고 8노드 클러스터 환경에서 성능을 비교해본다. 또한, 직렬화된 방법에 대한 성능향상(speedup)을 측정한다.