• 대한전기학회논문지
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• 제34권9호
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• pp.341-348
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• 1985

This paper deals with a surface charge simulation method of calculating three-dimensional electric fields and capacitance. The principle is to divide the electrode surface into rectangular or triangular elements of which charge density is the linear function of the electrode coordinate and to formulate a linear equation for the coefficients of charge density function and to determine those coefficients by boundary conditions. It has been shown that the method can give satisfactory results for thin rectangular plates where the other methods is difficult to be applied.

• Journal of the Korean Data and Information Science Society
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• 제10권2호
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• pp.415-428
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• 1999

In this paper, we study the saddlepoint approximations for the ratio of two independent sequences of random variables. In Section 2, we review the saddlepoint approximation to the probability density function. In section 3, we derive an saddlepoint approximation formular for the tail probability by following Daniels'(1987) method. In Section 4, we represent a numerical example which shows that the errors are small even for small sample size.

• Journal of the Korean Data and Information Science Society
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• 제23권1호
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• pp.219-225
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• 2012

We derive approximate maximum likelihood estimators of two parameters in a weighted exponential distribution, and derive the density function for the ratio Y=(X+Y) of two independent weighted exponential random variables X and Y, and then observe the skewness of the ratio density.

• 한국정보통신학회논문지
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• 제24권1호
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• pp.1-7
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• 2020

FCM(Fuzzy C-Means)으로 대표되는 퍼지 클러스터링은 간단하면서도 효율적인 클러스터링 방법이지만, FCM에서 사용하는 목적 함수에서는 밀도가 높은 클러스터가 클러스터링 결과에 많은 영향을 미치도록 함으로써 클러스터 사이의 밀도 차에 의해 클러스터링 결과에 왜곡이 발생할 수 있다. 이러한 밀도 문제를 완화하는 방법의 하나로 FCM의 목적 함수에 밀도 차이를 보정할 수 있는 항을 추가한 EDI-FCM(Extended Density-Independent FCM)이 있다. 이 논문에서는 레귤러라이제이션을 이용하여 EDI-FCM을 보완한 Regularized EDI-FCM을 제안한다. 레귤러라이제이션은 해공간을 평탄화하고 잡음 민감성을 줄이기 위해 흔히 사용되는 방법으로, 클러스터링에서는 특정 클러스터가 클러스터링 결과에 미치는 영향을 줄이는 역할을 한다. 제안하는 방법은 FCM이나 EDI-FCM과 비교했을 때 실제 클러스터 중심에 빠르고 정확하게 수렴한다는 것을 실험 결과를 통해 확인할 수 있다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2010년도 추계학술대회 논문집
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• pp.340-341
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• 2010

Noise reduction is an important factor to design low noise sensor array. In this paper three layers of the de-coupler in the conformal sensor array were used to investigate noise reduction. Conformal sensor array is positioned in the layers and the distance from the layer is 0.25cm~1.5cm. Transfer function in the frequency density function is investigated according to the three different positions. When increasing the embedded distance the flow noise decreased in the region of the kx>10.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 추계학술대회논문집
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• pp.298-303
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• 2003

The eccentric rotor system has various problems by vibration of unbalance mass. Specially, it is difficult to analyze vibration problem for the drum washing machine due to correlation of transmission paths. We analyze the mechanical structure by multidimensional spectral density to identify the maximum vibration magnitude at the frequency domain. It estimates the coherence function of the signals to pass the transmission paths. In case of the drum washing machine, because the transmission paths are correlated partially it needs to determinate the priority ranking. And the correlated parts are eliminated using conditioned spectral density function. Finally the shielding effect method confirms the reasonability of the modeling.

• 천문학회보
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• 제38권1호
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• pp.37.2-37.2
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• 2013

We present the galaxy luminosity function (LF) of the Abell 119 cluster. Deep images in u, g, r bands were taken using MOSAIC 2 CCD on a Blanco 4-m telescope at CTIO. Based on scaling relations at faint magnitudes and spectroscopy at bright magnitudes, accurate membership of galaxies is determined. The LF is fitted by a single Schechter function and a two components (Gauss + Schechter) function. Blue galaxies are well fitted by a single Schechter function with steep slope ${\alpha}$ ~ -1.55). Red galaxies in the inner, high density region are fitted by single Schechter function with shallow slope (${\alpha}$ ~ -1.30), while red galaxies in the outer, low density region are well fitted by a two components function. The different slope of LFs between the inner and outer seems to stem from the luminosity segregation of A119 indicating larger number ratio of luminous to faint ratio towards the cluster center. The different shape of LFs seems to be resulted from the different composition of luminous and faint galaxies among main-cluster, sub-cluster, and infall region.

• 한국전자파학회논문지
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• 제23권7호
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• pp.822-830
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• 2012

클러터는 레이더로 수신되는 불필요한 신호로 표적 탐지에 영향을 준다. 레이더 클러터는 진폭 분포, 주파수 스펙트럼 등과 같은 특성으로 정의되며, 이러한 특성을 충분히 고려하여 클러터 모델링 및 신호 생성이 되어야 한다. 본 논문에서는 다양한 클러터의 모델링에 광범위하게 사용되는 Weibull 분포 함수를 균일 분포 함수를 이용하여 단순화한 근사적 모델링 기법에 대하여 제안한다. 제안된 Weibull 분포 함수 근사 해에 의해 발생된 데이터가 원 Weibull 확률 밀도 함수를 만족하며, 생성 시간은 약 20 % 감소함을 실험 결과를 통하여 입증한다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 하계종합학술대회 논문집(2)
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• pp.221-224
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• 2002

Recently, simulation of Chemical Mechanical Polis hing is becoming more important because Process parameters on the material removal rate are complicated. And pattern-depent effects are a key concern in CMP processes. In this paper, we have been studied the changes of pattern density vs. oxide thickness with Stine's simulation model. We also have estimated the effective density using optimal window size with density mask, and have made a study of the change of oxide thickness as a function of polishing time.

• Journal of the Korean Statistical Society
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• 제24권2호
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• pp.349-360
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• 1995

This paper deals with the robustness properties of the minimum disparity estimation in linear regression models. The estimators defined as statistical quantities whcih minimize the blended weight Hellinger distance between a weighted kernel density estimator of the residuals and a smoothed model density of the residuals. It is shown that if the weights of the density estimator are appropriately chosen, the estimates of the regression parameters are robust.