• Communications for Statistical Applications and Methods
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• 제10권1호
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• pp.203-210
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• 2003

In a standard Metropolis-type Monte Carlo simulation, the proposal distribution cannot be easily adapted to "local dynamics" of the target distribution. To overcome some of these difficulties, Duane et al. (1987) introduced the method of hybrid Monte Carlo(HMC) which combines the basic idea of molecular dynamics and the Metropolis acceptance-rejection rule to produce Monte Carlo samples from a given target distribution. In this paper, using the HMC within Gibbs sampler, an asymptotical estimate of the smoothing mean and a general solution to state space modeling in Bayesian framework is obtaineds obtained.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2005년도 제24회 춘계학술대회논문집
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• pp.53-56
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• 2005

하이브리드 로켓은 기존의 고체, 액체 로켓에 비하여 많은 이점을 가지고 있다. 본 연구에서는 선회류 하이브리드 로켓을 설계 및 제작하여 regression rate의 증진 방안을 모색하고자 하였다. 산화제 선회강도의 변화에 따라 연소실 압력을 측정하여 추력을 계산하였으며, 연소과정의 가시화를 통해 근사적 regression rate를 측정하였다. 또한 하이브리드 로켓 시험 중 발생할 수 있는 문제점과 해결 방안도 제시하였다.

• 전기학회논문지
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• 제60권10호
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• pp.1817-1822
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• 2011

The fault current has been increasing due to expansive substation facilities for meeting the increase of demand. To limit increasing fault current in a power system, among methods the superconducting fault current limiter (SFCL) has been considered to be adopted in the power grid. However, in case of adopting SFCL in the power system, most of SFCLs need to solve problems such as recovery, cost. With efforts to solve those problems, the novel fault current limiting device which is called hybrid SFCL is developed. To apply the hybrid SFCL, it has to be needed to analyze application possibility and itself operation characteristics. In this paper, the fault current limiting and operation characteristics of hybrid SFCL with first half cycle the limiting operation in case of various resistances of superconducting element were analyzed through experiment.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2005년도 제25회 추계학술대회논문집
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• pp.311-317
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• 2005

하이브리드 로켓은 기존의 고체, 액체 로켓에 비하여 많은 이점을 가지고 있다. 본 연구에서는 선회류 하이브리드 로켓을 설계 및 제작하여 regression rate의 증진 방안을 모색하고자 하였다. 산화제 선회강도의 변화에 따라 연소실 압력을 측정하여 추력을 계산하였으며, 연소과정의 가시화를 통해 근사적 regression rate를 측정하였다. 또한 하이브리드 로켓 시험 중 발생할 수 있는 문제점과 해결 방안도 제시하였다.

• Wind and Structures
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• 제30권1호
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• pp.29-35
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• 2020

This paper presents a comparative structural analysis of lattice hybrid tower with six legs with conventional tubular steel tower for an onshore wind turbine using finite element method. Usually a lattice hybrid tower will have a conventional industry standard 'L' profile section for the lattice construction with four legs. In this work, the researcher attempted to identify and analyze the strength of six legged lattice hybrid tower designed with a special profile instead of four legged L profile. And to compare the structural benefits of special star profile with the conventional tubular tower. Using Ansys, a commercial FEM software, both static and dynamic structural analyses were performed. A simplified finite element model that represents the wind turbine tower was created using Shell elements. An ultimate load condition was applied to check the stress level of the tower in the static analysis. For the dynamic analysis, the frequency extraction was performed in order to obtain the natural frequencies of the tower.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2003년도 제21회 추계학술대회 논문집
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• pp.126-130
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• 2003

하이브리드 로켓은 기존의 고체, 액체 로켓에 비하여 많은 이점을 가지고 있다. 본 연구에서는 lab-scale의 하이브리드 모터를 설계 및 제작하여 regression rate의 증진 방안을 모색하고자 하였다. 산화제 유량의 변화에 따라 연소실 압력을 측정하여 추력을 계산하였으며, 연소과정의 가시화를 통해 근사적 regression rate를 측정하였다. 또한 하이브리드 로켓 시험 중 발생할 수 있는 문제점과 해결방안도 제시하였다.

• 한국경영과학회:학술대회논문집
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• 한국경영과학회 1996년도 추계학술대회발표논문집; 고려대학교, 서울; 26 Oct. 1996
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• pp.203-206
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• 1996

Prediction of firm bankruptcy have been extensively studied in accounting, as all stockholders in a firm have a vested interest in monitoring its financial performance. The objective of this paper is to develop the hybrid models for bankruptcy prediction. The proposed hybrid models are two phase. Phase one are (a) DA-assisted neural network, (b) Logit-assisted neural network, and (c) Genetic-assisted neural network. And, phase two are (a) DA-assisted Case based reasoning, and (b) Genetic-assisted Case based reasoning. In the variables selection, We are focusing on three alternative methods - linear discriminant analysis, logit analysis and genetic algorithms - that can be used empirically select predictors for hybrid model in bankruptcy prediction. Empirical results using Korean medium-sized firms data show that hybrid models are very promising neural network models and case based reasoning for bankruptcy prediction in terms of predictive accuracy and adaptability.

• Communications for Statistical Applications and Methods
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• 제18권5호
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• pp.645-655
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• 2011

Chandrasekar et al. (2004) introduced a generalized Type-II hybrid censoring. In this paper, we propose generalized doubly Type-II hybrid censoring. In addition, this paper presents the statistical inference on the scale parameter for the half logistic distribution when samples are generalized doubly Type-II hybrid censoring. The approximate maximum likelihood(AMLE) method is developed to estimate the unknown parameter. The scale parameter is estimated by the AMLE method using two di erent Taylor series expansion types. We compar the AMLEs in the sense of the mean square error(MSE). The simulation procedure is repeated 10,000 times for the sample size n = 20; 30; 40 and various censored samples. The $AMLE_I$ is better than $AMLE_{II}$ in the sense of the MSE.

• 한국정밀공학회지
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• 제23권2호
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• pp.172-180
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• 2006

Although there existed many types of manual/power hybrid wheelchairs, their use was not widespread because of their inconvenience in converting drive system and in folding frames. To carry a wheelchair in the car or to convert driving methods, some hard work of disassembling or exchanging wheels was required for most of currently available hybrid wheelchairs. In this study, the standard foldable manual wheelchair was reformed to a power wheelchair by installing the newly developed Axial Flux Permanent Magnet(AFPM) type of brush less direct current(BLDC) motor on each rear hub of wheelchair. This wheelchair could be driven by manual or electric power without exchanging. wheels, thus no additional work was needed for carriage or for power conversion. The developed wheelchair was evaluated for durability, stability, maneuverability, cost, and reliability in accordance with the Korean standards. The results indicated that the developed hybrid wheelchair was good enough for commercialization comparing to other imported wheelchairs.

• Structural Engineering and Mechanics
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• 제42권6호
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• pp.783-797
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• 2012

A new hybrid meta-heuristic optimization algorithm is presented for design of structures. The algorithm is based on the concepts of the charged system search (CSS) and the particle swarm optimization (PSO) algorithms. The CSS is inspired by the Coulomb and Gauss's laws of electrostatics in physics, the governing laws of motion from the Newtonian mechanics, and the PSO is based on the swarm intelligence and utilizes the information of the best fitness historically achieved by the particles (local best) and by the best among all the particles (global best). In the new hybrid algorithm, each agent is affected by local and global best positions stored in the charged memory considering the governing laws of electrical physics. Three different types of structures are optimized as the numerical examples with the new algorithm. Comparison of the results of the hybrid algorithm with those of other meta-heuristic algorithms proves the robustness of the new algorithm.