• 한국지능시스템학회논문지
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• 제23권5호
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• pp.418-422
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• 2013

본 논문은 비가우시안 노이즈가 존재하는 수중환경에서 비선형 필터 기법에 따른 2차원 위치 추정에 관한 연구 내용이다. 최근 위치 추정을 위한 필터로 확장형 칼만필터(EKF: Extended Kalman filter)가 많이 사용되고 있다. 하지만, 수중과 같은 비가우시안 노이즈가 존재하는 비선형 시스템에서는 많은 문제점을 가지고 있다. 따라서 본 논문에서는 상태변이의 예측을 기반으로한 EKF를 대신하여 통계적 발생인자 에 기반을 둔 분포 재해석 기법을 이용한 2차원 파티클필터 (TDPF: Two-Dimension Particle Filter)를 제안한다. 모의 실험을 통하여 Non-Gaussian Noise 가 존재하는 수중환경에서 제안하는 TDPF의 성능을 EKF와 비교분석하였으며 TDPF가 EKF보다 정확한 위치 추정결과를 제공하는 것을 확인하였다.

• 대한수학회보
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• 제54권4호
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• pp.1331-1336
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• 2017

Assume that R is a commutative Noetherian ring with non-zero identity, a is an ideal of R, X is an R-module, and t is a non-negative integer. In this paper, we present upper bounds for the injective dimension of X in terms of the injective dimensions of its local cohomology modules and an upper bound for the injective dimension of $H^t_{\alpha}(X)$ in terms of the injective dimensions of the modules $H^i_{\alpha}(X)$, $i{\neq}t$, and that of X. As a consequence, we observe that R is Gorenstein whenever $H^t_{\alpha}(R)$ is of finite injective dimension for all i.

• 대한기계학회논문집A
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• 제21권5호
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• pp.800-808
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• 1997

Decision process for length dimension in the mechanical system design process has been studied with a washing machine transmission as a model. The results are, (i) the length dimensions of the non-shaft elements are independent of other elements, (ii) the length dimensions of the shaft elements are dependent on the dimensions of the non-shaft elements located inside and outside of that elements, (iii) the length dimensions of the inner shaft elements are dependent on those of the outer shaft elements located parallel, (iv) the length dimensions of the shaft elements located serial are independent of each other.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2007년도 추계학술대회 논문집
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• pp.195-200
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• 2007

We analyzed a sequence of multi-stage automatic cold forging processes composed of four axisymmetric processes followed by a non-axisymmetric process using rigid-plastic finite element based forging simulators. The forging sequence selected for an example involves a piercing process and a heading process accompanying folding or overlapping, which all make it difficult to simulate the processes. To reduce computational time and to enhance the solution reliability, only the non-symmetric process was analyzed by the three-dimensional approach after the axisymmetric processes were analyzed by the two-dimensional approach. It has been emphsized that this capability is very helpful in simulating the multi-stage automatic forging processes which are next to axisymmetric.

• 대한수학회지
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• 제54권6호
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• pp.1759-1786
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• 2017

We examine the moduli space of oriented locally homogeneous manifolds of Type ${\mathcal{A}}$ which have non-degenerate symmetric Ricci tensor both in the setting of manifolds with torsion and also in the torsion free setting where the dimension is at least 3. These exhibit phenomena that is very different than in the case of surfaces. In dimension 3, we determine all the possible symmetry groups in the torsion free setting.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.1162-1168
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• 2008

This study provides how the Dimension Reduction (DR) method as an efficient technique for reliability analysis can acquire its increased efficiency when it is applied to highly nonlinear problems. In the highly nonlinear engineering systems, 4N+1 (N: number of random variables) sampling is generally recognized to be appropriate. However, there exists uncertainty concerning the standard for judgment of non-linearity of the system as well as possibility of diverse degrees of non-linearity according to each of the random variables. In this regard, this study judged the linearity individually on each random variable after 2N+1 sampling. If high non-linearity appeared, 2 additional sampling was administered on each random variable to apply the DR method. The applications of the proposed sampling to the examples produced the constant results with increased efficiency.

• 융합신호처리학회논문지
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• 제7권3호
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• pp.116-121
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• 2006

본 논문에서는 다양한 잡음환경에서의 실시간 적응화 기법을 적용하기 위한 선결 과제로 다차원 음성 특정 벡터를 저차원으로 축소하는 방법을 제안한다. 제안된 방법은 특징 벡터를 확률 우도 값으로 매핑시켜 비선형적으로 축소하는 방법으로 음성 / 비음성의 분류는 우도비 검증 (Likelihood Ratio Test; LRT) 을 이용하여 분류하였다. 실험 결과 고차원 특징 벡터를 이용하여 분류한 결과와 대등하게 분류됨을 확인할 수 있었다. 그리고, 제안된 방법에 의해 검출된 음성 데이터를 이용한 음성인식 실험에서도 10차 MFCC(Mel-Frequency Cepstral Coefficient)를 사용하여 분류한 경우와 대등한 인식률을 보여주었다.

• Wind and Structures
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• 제29권6호
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• pp.389-403
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• 2019

In this study, two original spectral representations of stationary stochastic fields, say the continuous proper orthogonal decomposition (CPOD) and the frequency-wavenumber spectral representation (FWSR), are derived from the Fourier-Stieltjes integral at first. Meanwhile, the relations between the above two representations are discussed detailedly. However, the most widely used conventional Monte Carlo schemes associated with the two representations still leave two difficulties unsolved, say the high dimension of random variables and the incompleteness of probability with respect to the generated sample functions of the stochastic fields. In view of this, a dimension-reduction model involving merely one elementary random variable with the representative points set owing assigned probabilities is proposed, realizing the refined description of probability characteristics for the stochastic fields by generating just several hundred representative samples with assigned probabilities. In addition, for the purpose of overcoming the defects of simulation efficiency and accuracy in the FWSR, an improved scheme of non-uniform wavenumber intervals is suggested. Finally, the Fast Fourier Transform (FFT) algorithm is adopted to further enhance the simulation efficiency of the horizontal stochastic wind velocity fields. Numerical examplesfully reveal the validity and superiorityof the proposed methods.

• 과학기술학연구
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• 제2권2호
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• pp.123-143
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• 2002

이 논문의 목적은 과학지식사회학의 대표적 사례 연구에 해당하는 보일의 공기펌프에 대한 세이핀의 연구를 중심으로 사회구성주의의 타당성을 검토하는 것이다. 나는 이 글에서 과학적 활동은 인식적 차원과 비인식적 차원을 갖고 있으며 사회구성주의는 후자를 강조한 나머지 전자의 중요성을 무시함으로써 과학적 지식에 대한 균형 잡힌 이해를 제공할 수 없다는 것을 주장한다. 논의 순서는 우선 진공펌프에 관한 보일과 홉스의 논쟁의 인식적 차원이 검토되고 이어서 비인식적 차원을 강조하는 세이핀의 설명이 검토된다. 이러한 논의를 바탕으로 세이핀의 사회구성주의의 한계점이 지적된다.

• The Journal of Asian Finance, Economics and Business
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• 제9권4호
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• pp.63-72
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• 2022

The study applied the non-financial dimensions of the Balanced Scorecard (customer dimension, internal processes dimension, learning, and growth dimension). It was done to evaluate performance and measure the effectiveness of these dimensions on performance evaluation at College of Science and Humanities Studies: Al Aflaj, Prince Sattam Bin Abdulaziz University. The researchers used the descriptive analytical approach to conduct the study to find the effect of these dimensions. Data was collected from the college staff and administrators; 120 questionnaires were distributed, out of which 112 were collected. The questionnaire data were analyzed using exploratory (EFA) and confirmatory factor analysis (CFA), hypotheses were tested using the structural equation modeling (SEM) through the (Spss) and (Amos) software. The study finding showed that the balanced scorecard had a positive contribution in evaluating the performance of the College of Science and Humanities Studies: Al Aflaj, Prince Sattam Bin Abdulaziz University through the dimensions of customers and internal processes, and the study finding revealed that the balanced scorecard has no contribution at performance evaluating the College of Science and Humanities Studies: Al Aflaj, Prince Sattam Bin Abdulaziz University through the dimension of learning and growth.