• 전산구조공학
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• 제9권4호
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• pp.219-228
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• 1996

힌지가 발생하는 철근콘크리트 골조구조물의 비선형해석시에 부재강성값을 사용하는 새로운 방법에 대한 연구이다. 본 연구에서는 부재의 비선형상태에서 힌지영역의 접선강성을 평가하고 효율적으로 이용하는 방법을 제시하였다. 비선형응답을 얻기위해 고유벡터를 이용하는 해석법은 비선형범위에서 시각증분에 따라 강성이 변하고 따라서 고유벡터군도 그 변하는 수만큼 재산정 하여야 하기 때문에 일반적인 해석방법이 아니다. 그러나 부재의 비선형상태를 나타내는 강성값, 즉 고유벡터의 산정횟수를 줄이며 산정된 기존값을 적절하게 재사용하여 해석의 효율성을 입증하였다. 지진하중을 받는 철근콘크리트 골조구조물의 비선형 해석의 경제성은 고유벡터의 산정횟수에 의존되기 때문에 고유벡터의 산정횟수를 감소시키며 신뢰성있는 응답을 구하여 본 해석법의 효율성을 입증하였다.

• Journal of Computing Science and Engineering
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• 제11권4호
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• pp.121-129
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• 2017

Feature selection has been widely established as an efficient technique for microarray data analysis. Feature selection aims to search for the most important feature/gene subset of a given dataset according to its relevance to the current target. Unsupervised feature selection is considered to be challenging due to the lack of label information. In this paper, we propose a novel method for unsupervised feature selection, which incorporates embedded learning and $l_{2,1}-norm$ sparse regression into a framework to select genes in microarray data analysis. Local tangent space alignment is applied during embedded learning to preserve the local data structure. The $l_{2,1}-norm$ sparse regression acts as a constraint to aid in learning the gene weights correlatively, by which the proposed method optimizes for selecting the informative genes which better capture the interesting natural classes of samples. We provide an effective algorithm to solve the optimization problem in our method. Finally, to validate the efficacy of the proposed method, we evaluate the proposed method on real microarray gene expression datasets. The experimental results demonstrate that the proposed method obtains quite promising performance.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2005년도 춘계 학술발표회 논문집
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• pp.627-632
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• 2005

In this study, a series of large-scale oedometer tests was performed to investigate the compressibility of rock fill materials. The testing samples were prepared to have three different grain size distributions and for each distribution, exist in two different states(dried and saturated). The test results indicated that particle breakages occurred mainly for the particles larger than 4.75mm in size and increased with increasing grain sizes. Also, it was found that, for a dry sample as it became well-graged, its compressibility decreased and accordingly, its tangent constrained modulus increased. A comparion between the samples in dry and saturated states revealed that compressibility of the materials increases with increasing water content. The values of tangent constrained modulus calculated for the tested dry samples were larger by about 10 to 20%, on average, than those for the saturated samples.

• 한국전산구조공학회논문집
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• 제18권2호
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• pp.169-179
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• 2005

탄성 및 비탄성좌굴 고유치해석법을 이용하여 강절프레임의 보-기둥부재의 유효좌굴길이를 산정하는 개선된 방법을 제시한다. 이를 위하여 먼저 설계기준에 제시된 압축재의 내하력 곡선식으로부터 접선계수이론(tangent modulus theory)에 근거하여 세장비-접선계수(tangent modulus), 응력-변형률 곡선식을 유도한다. 이때 안정함수를 이용하여 보-기둥요소의 접선강성행렬을 얻고, 비탄성 좌굴 고유치해석법을 제시하며 이를 이용하여 유효좌굴길이를 산정하는 방법을 제시한다. 해석예제를 통하여 강절프레임에 탄성 및 비탄성좌굴해석법에 의한 유효좌굴길이 비교결과를 제시하고, 매개변수 연구 결과를 제시한다.

• Structural Engineering and Mechanics
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• 제26권6호
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• pp.651-672
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• 2007

This study presents an improved method that uses the elastic and inelastic system buckling analyses for determining the K-factors of steel column members. The inelastic system buckling analysis is based on the tangent modulus theory for a single column and the application is extended to the frame structural system. The tangent modulus of an inelastic column is first derived as a function of nominal compressive stress from the column strength curve given in the design codes. The tangential stiffness matrix of a beam-column element is then formulated by using the so-called stability function or Hermitian interpolation functions. Two inelastic system buckling analysis procedures are newly proposed by utilizing nonlinear eigenvalue analysis algorithms. Finally, a practical method for determining the K-factors of individual members in a steel frame structure is proposed based on the inelastic and/or elastic system buckling analyses. The K-factors according to the proposed procedure are calculated for numerical examples and compared with other results in available references.

• Journal of Power Electronics
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• 제18권1호
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• pp.300-308
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• 2018

An online estimation method for wireless power transfer (WPT) systems is presented without using any measurement of the secondary side or the load. This parameter estimation method can be applied with a controlling strategy that removes both the receiving terminal controller and the wireless communication. This improves the reliability of the system while reducing its costs and size. In a wireless power transfer system with an LCCL impedance matching circuit under a rectifier load, the actual load value, voltage/current and mutual inductance can be reflected through reflected impedance measuring at the primary side. The proposed method can calculate the phase angle tangent value of the secondary loop circuit impedance via the reflected impedance, which is unrelated to the mutual inductance. Then the load value can be determined based on the relationships between the load value and the secondary loop impedance. After that, the mutual inductance and transfer efficiency can be computed. According to the primary side voltage and current, the load voltage and current can also be detected in real-time. Experiments have verified that high estimation accuracy can be achieved with the proposed method. A single-controller based on the proposed parameter estimation method is established to achieve constant current control over a WPT system.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 하계학술대회 논문집 Vol.6
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• pp.309-310
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• 2005

Generally, the dielectric constant and loss tangent are gotten by resonators. This paper presents analysis of the comparing the dielectric constant and loss tangent from the Ring, T and series gap structures. The T structure can be analyzed easily at wideband characteristic with simple design. the Ring can ignore the radiation loss from the open-ended effect. the Series gap can get more accurate permittivity than a Ring structure. The Used materials were dupont9599 LTCC ceramic and daeju0086 Ag.

• 대한조선학회논문집
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• 제31권2호
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• pp.15-21
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• 1994

전산기를 이용한 순정작업은 크게 두 가지로 구분할 수 있다. 첫번째는 단면곡선, 즉 2차원 곡선을 순정하고 다른 단면에서도 역시 부드러운가를 확인하는 전통적인 방법이다. 두번째는 곡면을 이용하는 것으로 전산기의 발달과 더불어 최근 많이 사용하고 있는 방법이다. 그러나 이 경우 먼저 선형을 곡면으로 정의하여야 하나 복잡한 선형의 경우 쉽지가 않다. 본 연구에서는 곡선의 순정기법을 확장하여 그물망 곡선(mesh curve)의 경우에 대해 비균일(non-uniform) B-Sp line 곡선을 이용한 Rong의 방법으로 선형의 순정작업을 행하였다. 그러나 Rong의 방법에는 곡선의 양 끝점에서의 기울기가 고정되어야 하는 제한이 있으며 곡면화 방법에 대한 기술이 명확하지 못하다. 본 연구에서는 곡선의 양끝의 기울기를 고정시키지 않고 순정작업을 할 수 있도록 하였으며, 순정된 결과를 곡면화하는 방법을 제안하였다.

• 한국컴퓨터정보학회논문지
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• 제11권3호
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• pp.107-115
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• 2006

본 논문에서는 캐스케이드 코릴레이션 학습 알고리즘을 위한 새로운 클래스의 활성화 함수를 소개한다. 이 함수는 코사인으로 모듈화된 가우스 함수로서 편의상 이 활성화 함수를 코스가우스(CosGauss) 함수라고 칭하기로 한다. 이 함수는 기존의 시그모이드 함수(sigmoidal function), 하이퍼볼릭탄젠트 함수(hyperbolic tangent function), 가우스 함수(gaussian function)에 비해서 등성이(ridge)를 더 많이 얻을 수 있다. 이러한 등성이들로 인하여 빠른 속도로 수렴하고 패턴인식 속도를 향상 시켜서 학습 능력을 향상시킬 수 있다. 캐스케이드 코릴레이션 네트워크에 이 활성화 함수를 사용하여 중요한 기준 문제(benchmark problem)의 하나인 이중나선 문제(two spirals problem)에 대하여 실험하여 다른 활성화 함수들과 결과 값을 비교하였다.

• 충청수학회지
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• 제34권1호
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• pp.37-53
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• 2021

In this paper we define scaled visual curvature and visual Frenet frame that can be visually accepted for discrete space curves. Scaled visual curvature is relatively simple compared to multi-scale visual curvature and easy to control the influence of noise. We adopt scaled minimizing directions of height functions on each neighborhood. Minimizing direction at a point of a curve is a direction that makes the point a local minimum. Minimizing direction can be given by a small noise around the point. To reduce this kind of influence of noise we exmine the direction whether it makes the point minimum in a neighborhood of some size. If this happens we call the direction scaled minimizing direction of C at p ∈ C in a neighborhood Br(p). Normal vector of a space curve is a second derivative of the curve but we characterize the normal vector of a curve by an integration of minimizing directions. Since integration is more robust to noise, we can find more robust definition of discrete normal vector, visual normal vector. On the other hand, the set of minimizing directions span the normal plane in the case of smooth curve. So we can find the tangent vector from minimizing directions. This lead to the definition of visual tangent vector which is orthogonal to the visual normal vector. By the cross product of visual tangent vector and visual normal vector, we can define visual binormal vector and form a Frenet frame. We examine these concepts to some discrete curve with noise and can see that the scaled visual curvature and visual Frenet frame approximate the original geometric invariants.