• Geomechanics and Engineering
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• 제15권4호
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• pp.947-955
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• 2018

In this study, we propose a three-dimensional simplified slope stability analysis using a hybrid-type penalty method (HPM). In this method, a solid element obtained by the HPM is applied to a column that divides the slope into a lattice. Therefore, it can obtain a safety factor in the same way as simplified methods on the slip surface. Furthermore, it can obtain results (displacement and strain) that cannot be obtained by conventional limit equilibrium methods such as the Hovland method. The continuity condition of displacement between adjacent columns and between elements for each depth is considered to incorporate a penalty function and the relative displacement. For a slip surface between the bottom surface and the boundary condition to express the slip of slope, we introduce a penalty function based on the Mohr-Coulomb failure criterion. To compute the state of the slip surface, an r-min method is used in the load incremental method. Using the result of the simple three-dimensional slope stability analysis, we obtain a safety factor that is the same as the conventional method. Furthermore, the movement of the slope was calculated quantitatively and qualitatively because the displacement and strain of each element are obtained.

• 대한전기학회논문지:전력기술부문A
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• 제50권1호
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• pp.1-5
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• 2001

In this paper, a new method for calculating the penalty factors of all generators including the slack bus is presented. A simple transposition of the angle reference, from the conventional slack bus to another bus where no generation exists, enables the derivation of the loss sensitivity of the slack bus. Penalty factors are obtained without any physical assumption through a simple substitution of the bus loss sensitivities. Penalty factors calculated by proposed method are not dependent on reference bus and can also be directly substituted into the general ELD equation for computing the optimal dispatch. Equations for loss sensitivities, Penalty factors and ELD are calculated simultaneously in normal power flow computation. A case study on a test system has proved the effectiveness of the proposed' angle reference transposition' method.

• Journal of Mechanical Science and Technology
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• 제16권10호
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• pp.1201-1210
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• 2002

A penalty frame method is proposed for the coupled analysis of finite elements with independently modeled substructures. Although previously reported hybrid interface method by Aminpour et al (IJNME, Vol 38, 1995) is accurate and reliable, it requires non-conventional special solution algorithm such as multifrontal solver. In present study, an alternative method has been developed using penalty frame constraints, which results in positive symmetric global stiffness matrices. Thus the conventional skyline solver or band solver can be utilized in the solution routine, which makes the present method applicable in the environment of conventional finite element commercial software. Numerical examples show applicability of the present method.

• Journal of applied mathematics & informatics
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• 제33권3_4호
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• pp.387-399
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• 2015

In this paper, a new smoothing approximation to the l₁ exact penalty function for constrained optimization problems (COP) is presented. It is shown that an optimal solution to the smoothing penalty optimization problem is an approximate optimal solution to the original optimization problem. Based on the smoothing penalty function, an algorithm is presented to solve COP, with its convergence under some conditions proved. Numerical examples illustrate that this algorithm is efficient in solving COP.

• 대한수학회보
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• 제55권4호
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• pp.1303-1315
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• 2018

For principal component analysis (PCA) to efficiently analyze large scale matrices, it is crucial to find a few singular vectors in cheaper computational cost and under lower memory requirement. To compute those in a fast and robust way, we propose a new stochastic method. Especially, we adopt the stochastic variance reduced gradient (SVRG) method [11] to avoid asymptotically slow convergence in stochastic gradient descent methods. For that purpose, we reformulate the PCA problem as a unconstrained optimization problem using a quadratic penalty. In general, increasing the penalty parameter to infinity is needed for the equivalence of the two problems. However, in this case, exact penalization is guaranteed by applying the analysis in [24]. We establish the convergence rate of the proposed method to a stationary point and numerical experiments illustrate the validity and efficiency of the proposed method.

• 대한의용생체공학회:의공학회지
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• 제38권5호
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• pp.219-226
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• 2017

Penalized-likelihood (PL) reconstruction methods for transmission tomography are known to provide improved image quality for reduced dose level by efficiently smoothing out noise while preserving edges. Unfortunately, however, most of the edge-preserving penalty functions used in conventional PL methods contain at least one free parameter which controls the shape of a non-quadratic penalty function to adjust the sensitivity of edge preservation. In this work, to avoid difficulties in finding a proper value of the free parameter involved in a non-quadratic penalty function, we propose a new adaptive method of space-variant smoothing with a simple quadratic penalty function. In this method, the smoothing parameter is adaptively selected for each pixel location at each iteration by using the image roughness measured by a pixel-wise standard deviation image calculated from the previous iteration. The experimental results demonstrate that our new method not only preserves edges, but also suppresses noise well in monotonic regions without requiring additional processes to select free parameters that may otherwise be included in a non-quadratic penalty function.

• 한국음향학회지
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• 제43권3호
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• pp.314-323
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• 2024

최근 해양 포유동물의 수동 음향 추적을 위해 스코어-패널티 법이 사용되고 있다. 전통적인 시간영역 정합장 처리 기법은 손실함수에 측정신호와 손실신호간의 정합도만을 고려하는 반면, 스코어-패널티법은 측정 신호와 모의신호의 비적합도를 반영하는 페널티 항도 추가로 고려한다. 본 연구에서는 스코어-패널티법을 파형을 알고 있는 수동표적의 심도 추정에 적용했다. 수중 음속 구조의 불확실성을 갖는 심해 환경을 가정하고, 스코어-패널티법의 성능을 평가했다. 또한 시간영역 정합장 처리기법의 결과와 서로 비교했다. 약한 수중 음속 오정합 환경에서 스코어-패널티법은 시간영역 정합장 처리기법보다 높은 정확도를 보이고 효율적으로 동작했다. 그렇지만 수중 음속 구조의 오정합이 매우 큰 경우에는 두 기법 모두 표적의 심도 추정에는 실패했다.

• Journal of the Korean Data and Information Science Society
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• 제28권4호
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• pp.721-731
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• 2017

이 연구에서는 Lasso 페널티 방법을 이용한 주성분분석 방법을 소개한다. 주성분분석에 Lasso 페널티를 적용하는 방법으로 흔히 사용되는 방법은 크게 두 가지가 있다. 첫 번째 방법은 주성분을 반응변수로 놓고 원 자료행렬을 설명변수로 하는 회귀분석의 회귀계수를 이용하여 최적의 선형결 합 벡터를 구할 때 Lasso 페널티 (일반적으로 elastic net 페널티)를 부과하는 방법이다. 두 번째 방법은 원자료행렬을 비정칙값 분해로 근사하고 남은 잔차행렬에 Lasso 페널티를 부과하여 최적의 선형결합 벡터를 구하는 방법이다. 이 연구에서는 주성분 분석에 Lasso 페널티를 부과하는 이 두 가지 방법들을 자세하게 개관하는데, 이 방법들은 변수 숫자가 표본크기보다 큰 경우에도 적용가능한 장점이 있다. 또한 실제 자료분석에서 R 프로그램을 통해 두 방법을 적용하고 그 결과를 비교한다. 구체적으로 변수 숫자가 표본크기보다 큰 Ahamad (1967)의 crime 자료에 적용한다.

• Communications for Statistical Applications and Methods
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• 제20권6호
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• pp.481-490
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• 2013

Classification is an important research area as data can be easily obtained even if the number of predictors becomes huge. The support vector machine(SVM) is widely used to classify a subject into a predetermined group because it gives sound theoretical background and better performance than other methods in many applications. The SVM can be viewed as a penalized method with the hinge loss function and penalty functions. Instead of $L_2$ penalty function Fan and Li (2001) proposed the smoothly clipped absolute deviation(SCAD) satisfying good statistical properties. Despite the ability of SVMs, they have drawbacks of non-robustness when there are outliers in the data. We develop a robust SVM method using a weight function with the SCAD penalty function based on the local quadratic approximation. We compare the performance of the proposed SVM with the SVM using the $L_1$ and $L_2$ penalty functions.

• 기계저널
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• 제21권4호
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• pp.259-263
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• 1981

본고의 목적은 제한조건이 있는 최소화(constrained minimization) 문제를 해석하는데 있어서 효과적인 방법으로 받아 들여지고있는 Penalty method 에 대한 간단한 개념과 이러한 류의 문제를 해석하는데 이미 사용되어 온 Lagrange multiplier method 와의 연관성, 그리고 이의 유한요소법에의 적용시 고려사항 등에 대하여 간략하게 소개하는데 있다.