• 호남수학학술지
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• 제46권1호
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• pp.47-59
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• 2024

The purpose of the Nash embedding theorem was to take extrinsic help for studying the intrinsic Riemannian geometry. To realize this aim in actual practice there is a need for optimal relationships between the known intrinsic invariants and the main extrinsic invariants for Riemannian submanifolds. This paper aims to provide an optimal relationship for CR-warped product submanifolds of locally conformal Kähler manifolds.

• 응용통계연구
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• 제14권1호
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• pp.81-90
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• 2001

모집단의 변화를 효과적으로 추정하기 위한 반복조사 방법으로 겨체표본조사를 고려할 수 있다. 교체표본조사는 크게 일수준교체표본조사와 다수준교체표본조사로 나누어지며 모집단의 특성, 특성의 변화를 추정하기 위하여 복합추정량을 사용하고 있다. 본 논문에서는 다수준교체표본조사의 경우 교체그룹내 표본개체들의 상관관계를 고려한 일반화복합추정량과 추정량의 분산을 최소화시키는 최적계수를제시하였다. 또한 수치예에서는 교체그룹내 표본개체의 수, 교체그룹내 상관정도의 변화에 따라 표본개체들의 상관관계를 고려한 일반화 복합추정량의 효율성을 제시하였다.

• Fisheries and Aquatic Sciences
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• 제23권7호
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• pp.19.1-19.14
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• 2020

Three generalized additive models were applied to the distribution of anchovy eggs and oceanographic factors to determine the occurrence of anchovy spawning grounds in Korean waters and to identify the indicators of their occurrence using survey data from the spring and summer of 1985, 1995, and 2002. Binomial and Gaussian types of generalized additive models (GAM) and quantile generalized additive models (QGAM) revealed that egg density was influenced mostly by ocean temperature and salinity in spring, and the vertical structure of temperature, salinity, dissolved oxygen, and zooplankton biomass during summer in the upper quantiles of egg density. The GAM and QGAM model deviance explained 18.5-63.2% of the egg distribution in summer in the East and West Sea. For the principle component analysis-based GAMs, the variance explained by the final regression model was 27.3-67.0%, higher than the regular models and QGAMs for egg density in the East and West Sea. By analyzing the distribution of anchovy eggs off the Korean coast, our results revealed the optimal temperature and salinity conditions, in addition to high production and high vertical mixing, as the key indicators of the major spawning grounds of anchovies.

• 한국농공학회논문집
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• 제51권3호
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• pp.53-62
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• 2009

This study was carried out to select optimal probability distribution based on design accumulated monthly mean inflow from the viewpoint of drought by Gamma (GAM), Generalized extreme value (GEV), Generalized logistic (GLO), Generalized normal (GNO), Generalized pareto (GPA), Gumbel (GUM), Normal (NOR), Pearson type 3 (PT3), Wakeby (WAK) and Kappa (KAP) distributions for the observed accumulative monthly mean inflow of Chungjudam. L-moment ratio was calculated using observed accumulative monthly mean inflow. Parameters of 10 probability distributions were estimated by the method of L-moments with the observed accumulated monthly mean inflow. Design accumulated monthly mean inflows obtained by the method of L-moments using different methods for plotting positions formulas in the 10 probability distributions were compared by relative mean error (RME) and relative absolute error (RAE) respectively. It has shown that the design accumulative monthly mean inflow derived by the method of L-moments using Weibull plotting position formula in WAK and KAP distributions were much closer to those of the observed accumulative monthly mean inflow in comparison with those obtained by the method of L-moment with the different formulas for plotting positions in other distributions from the viewpoint of RME and RAE.

• 한국습지학회지
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• 제17권3호
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• pp.251-263
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• 2015

본 연구에서는 L-moment ratio diagram 기법과 지형정보시스템(GIS)을 동시에 활용하여 우리나라의 지속기간별 연 최대강우량의 최적확률밀도함수를 판별하는 새로운 기법을 제안하고, 결과 도출과정에 있어 발견된 연최대강우량의 통계값의 흥미로운 지형학적 특성을 살펴보았다. 이를 위하여 우리나라 기상청에서 운영하는 67개의 강우관측지점에서 관측된 강우자료의 연최대강우량을 1시간, 3시간, 6시간, 12시간, 24시간 누적시간에 대하여 산출하고, L-moment ratio diagram 기법을 활용하여 이들에 대한 최적확률밀도함수를 구한 후, 이를 관측지점에 해당하는 티센 다각형에 다른 색상으로 표현하여 그 공간적 분포를 살펴보았다. 또한, 각 후보 확률밀도함수의 적합도에 대한 지도를 작성하였다. 본 연구의 결과를 요약하면 다음과 같다: (1) 강우의 극한값의 특성을 대표할 수 있는 통계값인 L-skewness와 L-kurtosis는 뚜렷한 공간적 경향을 띠고 있다. 특히 산맥을 포함한 우리나라의 지형적 특성에 큰 영향을 받았다. 이는 발생빈도가 높고 강도가 낮은 평상시의 강우사상뿐 만 아니라, 연최대강우량 또한 지형의 영향을 크게 받는다는 것을 의미한다; (2) 우리나라의 산악지역에서는 연최대강우량의 통계적 특성에 대한 고도의 영향이 비산악지역보다 더 크며, 고도가 높은 지역일수록 발생 빈도가 낮고 강도가 강한 강우사상이 더 자주 발생하며, 강우의 누적기간이 증가할수록 이러한 경향은 작아졌다; (3) 우리나라의 연최대강우량을 가장 잘 대변할 수 있는 확률밀도함수는 Generalized Extreme Value (GEV) 분포와 Generalized Logistic (GLO) 분포이다. 단, 남해안의 중앙지역에 대해서는 Generalized Pareto (GPA) 분포가 가장 적합한 것으로 나타났다.

• 전자공학회논문지SC
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• 제43권5호
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• pp.68-79
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• 2006

ECT는 측정된 커패시턴스 값을 이용하여 유전 물체의 유전율 분포를 가시화하기 위해 사용되는 비접촉 영상 복원 기술이다. 영상 복원시 수렴 속도 개선과 영상의 질 향상을 위해 다양한 반복적 영상 복원 방법들이 있으며, Landweber 방법은 널리 사용되고 있는 ECT의 영상 복원 방법 중 하나이다. 본 논문에서는 ECT 영상 복원에서 수렴 속도를 개선하기 위해 수정된 generalized Landweber 방법을 제안한다. 특히, Shaping 행렬을 가지는 generalized Landweber 방법에 가속항을 추가하고 최적화 계수를 해석적으로 결정한다. 다양한 컴퓨터 모의 실험을 통해 제안한 방법의 타당성을 입증한다.

• International Journal of Precision Engineering and Manufacturing
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• 제3권2호
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• pp.15-21
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• 2002

A control-structure combined optimal design problem is discussed taking a 3-D truss structure as a design object. We use descriptor forms for a controlled object and a generalized plant because the structural parameters appear naturally in these farms. We consider not only minimum weight design problem for structure system, but also suppression problem of the effect of disturbances for control system as the purpose of the design. A numerical example shows the validity of combined optimal design of structure and control systems. We also consider the validity of sensor-actuator collocation for control system design in this paper.

• 품질경영학회지
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• 제31권3호
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• pp.185-192
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• 2003

In this paper, the properties on the optimal replacement policies for the general failure model are developed. In the general failure model, two types of system failures may occur : one is Type I failure (minor failure) which can be removed by a minimal repair and the other, Type II failure (catastrophic failure) which can be removed only by complete repair. It is assumed that, when the unit fails, Type I failure occurs with probability 1-p and Type II failure occurs with probability p, $0\leqp\leq1$. Under the model, the system is minimally repaired for each Type I failure, and it is repaired completely at the time of the Type II failure or at its age T, whichever occurs first. We further assume that the repair times are non-negligible. It is assumed that the minimal repair times in a renewal cycle consist of a strictly increasing geometric process. Under this model, we study the properties on the optimal replacement policy minimizing the long-run average cost per unit time.

• Journal of the Korean Statistical Society
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• 제30권1호
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• pp.163-178
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• 2001

We consider the experimental design problem of selecting values of design variables x for observation of a response y that depends on x and on model parameters $\theta$. The form of the dependence may be quite general, including all linear and nonlinear modeling situations. The goal of the design selection is to efficiently estimate functions of $\theta$. Three new criteria for selecting design points x are presented. The criteria generalized the usual Bayesian optimal design criteria to situations n which the prior distribution for $\theta$ amy be uncertain. We assume that there are several possible prior distributions,. The new criteria are applied to the nonlinear problem of designing to estimate the turning point of a quadratic equation. We give both analytic and computational results illustrating the robustness of the optimal designs based on the new criteria.

• 대한전자공학회논문지
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• 제26권11호
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• pp.1829-1838
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• 1989

This paper is proposed one method of the exact optimal switching pattern of Selected Harmonic Elimination(SHE) Pulse Width Modulation(PWM). It defined Harmonic Elimination Band (HEB) at Constant Voltage(CV) and sought all solutions which are included HEB. Then, it calculated the Generalized Klirr Factor(GKF) beling to this solution and decided the optimal switching pattern which is minimized GKF. This optimal switching solution is used as initial condition of Newto Raphson(NR) method of decided easily switching pattern at Variable Voltage(VV). We desined the inverter by Power Transister(PTR) and implemented variable speed drive of Induction Motor(IM) in order to verify the validity of this theoretical proposition, then shown this results by comparison and analysis.