• 한국통계학회:학술대회논문집
• /
• 한국통계학회 2002년도 춘계 학술발표회 논문집
• /
• pp.67-72
• /
• 2002

A Bayesian testing procedure is proposed for assessment of bioequivalence in both mean and variance which ensures population bioequivalence under normality assumption. We derive the joint posterior distribution of the means and variances in a standard 2 ${\times}$ 2 crossover experimental design and propose a Bayesian testing procedure for bioequivalence based on a Markov chain Monte Carlo methods. The proposed method is applied to a real data set.

• Journal of the Korean Data and Information Science Society
• /
• 제18권3호
• /
• pp.645-657
• /
• 2007

Several statistical procedures for assessment of bioequivalence of variabilities between two drug formulations in bioequivalence trials are reviewed and modified methods for assessing total variability are suggested. The problem of the current US FDA aggregate criterion for population bioequivalence and the necessity of disaggregate criterion are discussed with an illustrated example.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1997년도 추계학술대회 논문집 학회본부
• /
• pp.257-260
• /
• 1997

This paper designs the optimal PID controller for load frequency control on 2-area power system. Genetic algorithm is utilized to optimize parameters of PID controller which is applied to power system. Using two-point crossover, uniform crossover and one-point crossover, Search performance of genetic algorithm with each crossover method is considered. In case of load variation in 1-area, the dynamic characteristic of power system is considered. The simulation results show that the proposed PID controller is better control performance than PID controller using Ziegler-Nichols method.

• Communications for Statistical Applications and Methods
• /
• 제23권6호
• /
• pp.543-553
• /
• 2016

The validity of statistical inference depends on proper randomization methods. However, even with proper randomization, we can have imbalanced with respect to important characteristics. In this paper, we introduce a method based on ranked auxiliary variables for treatment allocation in crossover designs using Latin squares models. We evaluate the improvement of the efficiency in treatment comparisons using the proposed method. Our simulation study reveals that our proposed method provides a more powerful test compared to simple randomization with the same sample size. The proposed method is illustrated by conducting an experiment to compare two different concentrations of titanium dioxide nanofiber (TDNF) on rats for the purpose of comparing weight gain.

• Journal of the Korean Data and Information Science Society
• /
• 제28권4호
• /
• pp.743-754
• /
• 2017

두 제제의 생체이용률을 비교하여 동등성을 입증하는 생물학적 동등성 시험은 표준 $2{\times}2$ 교차설계를 원칙으로 하고 있으나, 최근에는 제제의 특성이 고변동성으로 인해 표준 $2{\times}2$ 교차설계를 사용할 경우 지나치게 많은 피험자가 필요하게 되면서, EMA나 MFDS 등에서는 $2{\times}2$ 교차설계를 확장한 $2{\times}4$, $4{\times}2$ 또는 $4{\times}4$ 등의 고차원 설계를 권장하고 있다. $2{\times}3$ 교차설계는 표준 $2{\times}2$ 교차설계에서 1기간을 확장한 설계로 불균형 설계이기는 하지만 $2{\times}4$ 교차설계와 비교해서 경제적, 윤리적 측면에서 장점을 갖고 있는 설계라 할 수 있다. 본 연구에서는 $2{\times}3$ 이중설계를 활용하는 생물학적 동등성 시험에서 설계의 통계적 특성을 고찰해 보고, 생물학적 동등성 평가를 위한 통계적 설계 및 추론 절차를 새롭게 개정된 의약품동등성시험기준을 적용하여 논의한다.

• 응용통계연구
• /
• 제20권1호
• /
• pp.39-52
• /
• 2007

협심증 치료의 신약에 대한 교차계획 임상시험(crossover clinical trials)에서 신약의 효능을 알아보는 운동테스트(treadmill exercise test) 결과는 중도절단 생존시간(censored survival times)으로 측정된다. 이 논문에서는 교차계획에서 수집된 중도절단 생존자료의 여러 가지 분석법에 대해 설명한다. 중도절단을 감안한 비모수적 방법들과 층화 Cox 비례위험모형 (stratified Cox proportional hazards model)에 근거한 분석법이 제시되었다. 한편, 교차계획의 두 시기에 걸쳐 수집된 생존시간의 차(difference)로부터 구간절단자료(interval censored data)가 생성되며 이에 근거한 분석법으로서 이 논문에서는 구간절단자료에 대한 Cox 비례위험모형 (proportional hazards model)의 가능성을 알아보며, 예제 자료로써 여러 방법들의 결과를 비교해 본다.

• International Journal of Fluid Machinery and Systems
• /
• 제3권1호
• /
• pp.11-19
• /
• 2010

The performance of the crossover system of a centrifugal compressor stage consisting of static components of $180^{\circ}$ U-bend, return channel vanes and exit ducting with a $90^{\circ}$ bend is investigated. This study is confined to the assessment of performance of the crossover system by varying the shape of the return channel vanes. For this purpose two different types of Return Channel Vanes (RCV1 and RCV2) were experimentally investigated. The performance of the crossover system is discussed in terms of total pressure loss coefficient, static pressure recovery coefficient and vane surface pressure distribution. The experimentation was carried out on a test setup in which static swirl vanes were used to simulate the flow at the exit of an actual centrifugal compressor impeller with a design flow coefficient of 0.053. The swirl vanes are connected to a mechanism with which the flow angle at the inlet of U-bend could be altered. The measurements were taken at five different operating conditions varying from 70% to 120% of design flow rate. On an overall assessment RCV1 is found to give better performance in comparison to RCV2 for different U-bend inlet flow angles. The performance of RCV2 was verified using numerical studies with the help of a CFD Code. Three dimensional sector models were used for simulating the flow through the crossover system. The turbulence was predicted with standard k-$\varepsilon$, 2-equation model. The iso-Mach contour plots on different planes and development of secondary flows were visualized through this study.

• Asia Marketing Journal
• /
• 제11권3호
• /
• pp.151-165
• /
• 2009

본 사례는 Crossover Utility Vehicle (CUV)의 선구자인 기아자동차 SOUL이 혁신적인 제품전략을 통하여 어떻게 새로운 시장을 개척하였는지를 분석하고 있다. 지금까지 대부분의 자동차 제조업체들은 전통적인 시장세분화 기준에 치중하여, 여러 소비자 계층들을 동시에 만족시킬 수 있는 신제품 개발의 기회를 놓치고 있었다. 기아자동차 SOUL은 여러 소비자 계층을 만족시킬 수 있는 제품에 대한 기회를 포착하고, 기존 소비자 계층별 가치를 통합적으로 제공하여 새로운 시장을 열었다. 본 사례는 포화상태에 있는 자동차 산업에서 혁신적인 제품전략을 통해 신시장을 개척하는 과정을 잘 보여주고 있다. 기아자동차 SOUL의 혁신적 제품전략을 크게 디자인 혁신, CUV 시장 개척, 고객을 위한 맞춤서비스 제공, 그리고 기능 혁신의 4가지 축으로 설명하고 있다. 기아자동차 SOUL의 혁신적인 제품전략은 블루오션 개척을 계획하고 있는 많은 기업에게 의미 있는 시사점을 제공해 준다.

• 한국CDE학회논문집
• /
• 제1권3호
• /
• pp.234-241
• /
• 1996

Recently, Genetic Algorithms(GAs), which consist of genetic operators named selection crossover and mutation, are widely adapted into a search procedure for structural optimization. Contrast to traditional optimal design techniques which use design sensitivity analysis results, GAs are very simple in their algorithms and there is no need of continuity of functions(or functionals) any more in GAs. So, they can be easily applicable to wide territory of design optimization problems. Also, virtue to multi-point search procedure, they have higher probability of convergence to global optimum compared with traditional techniques which take one-point search method. The introduction of basic theory on GAs, and the application examples in combination optimization of ten-member truss structure are presented in this paper.

• 상하수도학회지
• /
• 제12권1호
• /
• pp.70-80
• /
• 1998

Many algorithms to find a minimum cost design of water distribution network (WDN) have been developed during the last decades. Most of them have tried to optimize cost only while satisfying other constraining conditions. For this, a certain degree of simplification is required in their calculation process which inevitably limits the real application of the algorithms, especially, to large networks. In this paper, an optimum design method using the Genetic Algorithms (GA) is developed which is designed to increase the applicability, especially for the real world large WDN. The increased to applicability is due to the inherent characteristics of GA consisting of selection, reproduction, crossover and mutation. Just for illustration, the GA method is applied to find an optimal solution of the New York City water supply tunnel. For the calculation, the parameter of population size and generation number is fixed to 100 and the probability of crossover is 0.7, the probability of mutation is 0.01. The yielded optimal design is found to be superior to the least cost design obtained from the Linear Program method by $4.276 million.