• 한국정보통신학회논문지
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• 제17권8호
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• pp.1891-1898
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• 2013

3차원 그래픽 API인 OpenGL과 Direct3D를 효율적으로 처리하기 위해 sine, cosine, 역수, 역제곱근, 지수 및 로그 연산을 처리하는 부동소수점 연산회로를 설계하였다. 고속 연산과 2 ulp 보다 작은 오차를 만족시키기 위해 2차 최대최소 근사 방식과 테이블 룩업 방식을 사용하였다. 설계된 회로는 65nm CMOS 표준 셀 조건에서 2.3-ns의 최대 지연시간을 갖고 있으며, 약 23,300 게이트로 구성된다. 최대 400 MFLOPS의 연산 성능과 높은 정밀도로, 설계한 연산회로는 3차원 모바일 그래픽 분야에 효율적으로 적용 가능하다.

• Journal of the Korean Data and Information Science Society
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• 제17권2호
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• pp.543-557
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• 2006

This paper is concerned with the applicability of the chi-square approximation to the six disparity statistics: the Pearson chi-square, the generalized likelihood ratio, the power divergence, the blended weight chi-square, the blended weight Hellinger distance, and the negative exponential disparity statistic. Three dimensional contingency tables of small and moderate sample sizes are generated to be fitted to all possible hierarchical log-linear models: the completely independent model, the conditionally independent model, the partial association models, and the model with one variable independent of the other two. For models with direct solutions of expected cell counts, point estimates and confidence intervals of the 90 and 95 percentage points of six statistics are explored. For model without direct solutions, the empirical significant levels and the empirical powers of six statistics to test the significance of the three factor interaction are computed and compared.

• Journal of applied mathematics & informatics
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• 제10권1_2호
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• pp.245-250
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• 2002

Consider the Convex Polygon Pm={Al , A2, ‥‥, Am} With Vertex points A$\_$i/ = (a$\_$i/, b$\_$i/),i : 1,‥‥, m, interior P$\^$0/$\_$m/, and length of perimeter denoted by L(P$\_$m/). Let R$\_$n/ = {B$_1$,B$_2$,‥‥,B$\_$n/), where B$\_$i/=(x$\_$i/,y$\_$I/), i =1,‥‥, n, denote a regular polygon with n sides of equal length and equal interior angle. Kaiser[4] used the regular polygon R$\_$n/ to approximate P$\_$m/, and the problem examined in his work is to position R$\_$n/ with respect to P$\_$m/ to minimize the area of the symmetric difference between the two figures. In this paper we give the quality of a approximating regular polygon R$\_$n/ to approximate P$\_$m/.

• ETRI Journal
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• 제26권4호
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• pp.297-306
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• 2004

A plasma is a collection of charged particles and on average is electrically neutral. In fabricating integrated circuits, plasma etching is a key means to transfer a photoresist pattern into an underlayer material. To construct a predictive model of plasma-etching processes, a polynomial neural network (PNN) is applied. This process was characterized by a full factorial experiment, and two attributes modeled are its etch rate and DC bias. According to the number of input variables and type of polynomials to each node, the prediction performance of the PNN was optimized. The various performances of the PNN in diverse environments were compared to three types of statistical regression models and the adaptive network fuzzy inference system (ANFIS). As the demonstrated high-prediction ability in the simulation results shows, the PNN is efficient and much more accurate from the point of view of approximation and prediction abilities.

• 한국전산유체공학회지
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• 제11권1호
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• pp.21-28
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• 2006

Reliability Based Design Optimization(RBDO) is one of the optimization methods that minimize the product failure due to small changes of operating conditions or process errors. It searches the optimum that satisfies the safety margin of each constraint, and it gives stable and reliable designs. However, RBDO requires many times oj computational efforts compared with the conventional deterministic optimization(DO) to evaluate the probability of failure about each constraint, therefore it is hard to apply directly to large-scaled problems such as a flexible wing shape design optimization. For the efficient reliability analysis, the approximate reliability analysis method with the two-point approximation(TPA) is proposed In this study, the lift-to-drag ratio maximization designs are performed with 3-dimensional Navier-Stokes analysis and NASTRAN structural analysis, and the optimization results about the deterministic, FORM and SORM are compared.

• International Journal of Aeronautical and Space Sciences
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• 제16권4호
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• pp.510-519
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• 2015

Concerning the issue of high-dimensions, hybrid uncertainties of randomness and intervals including implicit and highly nonlinear limit state function, reliability analysis based on the hybrid uncertainty reliability mode combining with back propagation neural network (HU-BP neural network) is proposed in this paper. Random variables and interval variables are as input layer of the neural network, after the training and approximation of the neural network, the response variables are obtained through the output layer. Reliability index is calculated by solving the optimization model of the most probable point (MPP) searching in the limit state band. Two numerical cases are used to demonstrate the method proposed in this paper, and finally the method is employed to solving an engineering problem of the aerospace friction plate. For this high nonlinear, small failure probability problem with interval variables, this method could achieve a good analysis result.

• 기술혁신학회지
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• 제8권3호
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• pp.887-910
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• 2005

This paper attempts to approximate the distribution function for the number of innovation activities (NIA). To this end, the dataset of 2002 Korean Innovation Survey (KIS 2002) published by Science and Technology Policy Institute is used. To deal with zero NTI values given by a considerable number of firms in the KIS 2002 survey, a mixture model of distributions for NIA is applied. The NIA is specified as a mixture of two distributions, one with a point mass at zero and the other with full support on the positive half of the real line. The model was empirically verified for the KIS 2002 data. The mixture model can easily capture the common bimodality feature of the NIA distribution. In addition, when covariates were added to the mixture model, it was found that the probability that a firm has zero NIA significantly varies with some variables.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 추계학술대회 논문집 학회본부 B
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• pp.603-605
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• 1998

In recent years, chip delay estimation has had an increasingly important impact on overall design technology. The analysis of the timing behavior of an ASIC should be based not only on the delay characteristics of gates and interconnect circuits but also on the interactions between them. This model plays an important role in our CAD system to analyze the ASIC timing characteristics accurately, together with two-dimensional gate delay table model, AWE algorithm and effective capacitance concept. In this paper, we present an efficient algorithm which accounts for series resistance by computing a reduced-order approximation for the driving-point admittance of an RC-tree and an effective capacitance equation that captures the complete waveform response accurately.

• 터널과지하공간
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• 제25권1호
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• pp.56-67
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• 2015

본 논문에서는 횡등방성 매질에 적용 가능한 음원추적기법을 제안하고 이를 실험적으로 검증하였다. 분할근사법을 바탕으로 매질의 속도 이방성을 고려하였으며 이 방법은 단순한 계산을 통하여 음원추적을 가능하게 한다. AE 측정 결과로부터 P파 도달시간을 결정할 때 Two-step AIC 알고리즘을 적용하였고 이 실험결과와 분할된 요소를 비교하여 최소 오차 요소를 음원의 위치로 결정하였다. 개발된 알고리즘의 적용성을 검증하기 위하여 시멘트 모르타르를 이용한 인공 횡등방성 시험편을 제작하고 연필심 압절을 음원으로 하는 일련의 시험을 수행하였다. 연필심 압절 위치와 음원추적 결과 간의 거리를 절대오차로 정의할 때, 1.60 mm ~ 14.46 mm의 오차범위와 8.57 mm의 평균오차가 측정되었고 이는 시험편과 AE 센서의 크기를 고려할 때 수용할 만한 수준인 것으로 판단되었다. 또한, 서로 다른 검출한계 수준에 따른 음원추적 결과를 비교했을 때 비슷한 수준의 오차가 측정되어 본 기법은 실험 시 배경잡음의 영향을 적게 받는 것으로 판단된다. 측정된 절대오차를 각 축방향 오차로 분해하여 AE 센서 부착위치의 영향을 파악할 수 있었으며 센서의 최적 위치를 결정하면 더 정밀한 음원추적 결과를 얻을 수 있을 것으로 판단된다.

• Journal of the Korean Data and Information Science Society
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• 제9권2호
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• pp.345-355
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• 1998

다층전방향 신경망을 학습시키기 위해 역전파 알고리즘이 널리 사용되고 있으나 이 알고리즘은 긴 훈련시간, 극소점 문제, 이상치에 민감하다는 단점을 가지고 있다. 한편 실제문제에서는 많은 경우에 자료에 과대오차와 이상치가 포함되게 된다. 따라서 과대 오차에 민감하지 않고, 이상치의 영향을 최소화시키는 로버스트 역전파 알고리즘의 필요성이 대두되었다. 본 논문에서는 기존의 두종류의 로버스트 역전파 알고리즘을 이론적으로 비교하고 비선형 회귀 함수추정과 문자인식과 같은 패턴인식 문제에 적용하여 실험결과를 분석한다. 그리고 향후 연구과제로 신경망 학습을 위해 베이지안 기법의 사용을 제안한다.