• Communications for Statistical Applications and Methods
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• v.6 no.2
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• pp.601-610
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• 1999

Crossover design is officially except for special occasions recommended by KFDA and FDA for assessing Bioequivalence between two drugs one for reference and the other for innovator. Such design is regarded as a special case of latin square split-polt or repeated measurement design and its main difference with other designing methods is that each subject in an experiment is exposed two drugs in sequence. Therefore general statistical analysis is not suitable since the model for this experiment includes carryover effect in addition to period and sequence effect. in this paper analysis for crossover model with two drugs and its interpretation are mainly discussed and an example is given for illustration.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.39 no.4
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• pp.81-89
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• 2016

Distributed genetic algorithm (DGA), also known as island model or coarse-grained model, is a kind of parallel genetic algorithm, in which a population is partitioned into several sub-populations and each of them evolves with its own genetic operators to maintain diversity of individuals. It is known that DGA is superior to conventional genetic algorithm with a single population in terms of solution quality and computation time. Several researches have been conducted to evaluate effects of parameters on GAs, but there is no research work yet that deals with structure of DGA. In this study, we tried to evaluate performance of various genetic algorithms (GAs) for the famous symmetric traveling salesman problems. The considered GAs include a conventional serial GA (SGA) with IGX (Improved Greedy Crossover) and several DGAs with various combinations of crossover operators such as OX (Order Crossover), DPX (Distance Preserving Crossover), GX (Greedy Crossover), and IGX. Two distinct immigration policies, conventional noncompetitive policy and newly proposed competitive policy are also considered. To compare performance of GAs clearly, a series of analysis of variance (ANOVA) is conducted for several scenarios. The experimental results and ANOVAs show that DGAs outperform SGA in terms of computation time, while the solution quality is statistically the same. The most effective crossover operators are revealed as IGX and DPX, especially IGX is outstanding to improve solution quality regardless of type of GAs. In the perspective of immigration policy, the proposed competitive policy is slightly superior to the conventional policy when the problem size is large.

• Journal of Preventive Medicine and Public Health
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• v.46 no.1
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• pp.10-18
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• 2013

Objectives: We investigated the association between particulate matter less than $10{\mu}m$ in aerodynamic diameter ($PM_{10}$) exposure and non-accidental mortality in Asian populations by meta-analysis, using both time-series and case-crossover analysis. Methods: Among the 819 published studies searched from PubMed and EMBASE using key words related to $PM_{10}$ exposure and non-accidental mortality in Asian countries, 8 time-series and 4 case-crossover studies were selected for meta-analysis after exclusion by selection criteria. We obtained the relative risk (RR) and 95% confidence intervals (CI) of non-accidental mortality per $10{\mu}g/m^3$ increase of daily $PM_{10}$ from each study. We used Q statistics to test the heterogeneity of the results among the different studies and evaluated for publication bias using Begg funnel plot and Egger test. Results: Testing for heterogeneity showed significance (p<0.001); thus, we applied a random-effects model. RR (95% CI) per $10{\mu}g/m^3$ increase of daily $PM_{10}$ for both the time-series and case-crossover studies combined, time-series studies relative risk only, and case-crossover studies only, were 1.0047 (1.0033 to 1.0062), 1.0057 (1.0029 to 1.0086), and 1.0027 (1.0010 to 1.0043), respectively. The non-significant Egger test suggested that this analysis was not likely to have a publication bias. Conclusions: We found a significant positive association between $PM_{10}$ exposure and non-accidental mortality among Asian populations. Continued investigations are encouraged to contribute to the health impact assessment and public health management of air pollution in Asian countries.

• Korean Journal of Microbiology
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• v.49 no.1
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• pp.1-7
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• 2013

During meiosis, genetic recombinants are formed by homologous recombination accompanying with the programmed double-strand breaks (DSBs) and strand exchanges between homologous chromosomes. The mechanism is generated by recombination intermediates such as single-end invasions (SEIs) and double-Holliday junctions (dHJs), and followed by crossover (CO) or non-crossover (NCO) products. Our study was focused on the analysis of meiotic recombination intermediates (DSBs, SEIs, and dHJs) and final recombination products (CO and NCO). We identified these meiotic recombination intermediates using DNA physical analysis under HIS4LEU2 "hot spot" system in budding yeast, Saccharomyces cerevisiae. For DNA physical analysis, when the hot spot locus is recognized by restriction enzyme from synchronous meiotic cells, the fragmented DNA that are forming recombination intermediates can be detected and quantified through Southern hybridization analysis. Our study suggests that this system can analyze the structural change of recombination intermediates during DSB-SEI transition, double-Holiday junctions and crossover/non-crossover products in meiosis.

• Korean Journal of Chemical Engineering
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• v.35 no.11
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• pp.2290-2295
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• 2018

An acceleration stress test (AST) was performed to evaluate the durability of a polymer membrane in a polymer electrolyte membrane fuel cell (PEMFC) for 500 hours. Previous studies have shown that hydrogen crossover measured by linear sweep voltammetry (LSV) increases when the polymer membrane deteriorates in the AST process. On the other hand, hydrogen crossover of the membrane often decreases in the early stages of the AST test. To investigate the cause of this phenomenon, we analyzed the MEA operated for 50 hours using the AST method (OCV, RH 30% and $90^{\circ}C$). Cyclic voltammetry and transmission electron showed that the electrochemical surface area (ECSA) decreased due to the growth of electrode catalyst particles and that the hydrogen crossover current density measured by LSV could be reduced. Fourier transform infrared spectroscopy and thermogravimetric/differential thermal analysis showed that -S-O-S- crosslinking occurred in the polymer after the 50 hour AST. Gas chromatography showed that the hydrogen permeability was decreased by -S-O-S- crosslinking. The reduction of the hydrogen crossover current density measured by LSV in the early stages of AST could be caused by both reduction of the electrochemical surface area of the electrode catalyst and -S-O-S- crosslinking.

• Proceedings of the PSK Conference
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• 2003.04a
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• pp.117.2-118
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• 2003

Sample size calculations plays an important role in a bioequivalence trials and is determined by considering power under the alternative hypothesis. The regulatory guideline recommends that $2{\times}2$ crossover design is conducted and raw data is log-transformed for statistical analysis. In this paper, we discuss the sample size calculation in $2{\times}2$ crossover design with the log-transformed data.

• Journal of Korean Society of Transportation
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• v.22 no.2 s.73
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• pp.43-54
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• 2004

This study analyzes characteristics and applicability of genetic algorithms and genetic operators to optimize highway alignments. Genetic algorithms, one of artificial intelligence techniques, are fast and efficient search algorithms for generating, evaluation and finding optimal highway alignment alternatives. The performance of genetic algorithms as an optimal search tool highly depends on genetic operators that are designed as a problem-specific. This study adopts low mutation operators(uniform mutation operator, straight mutation operator, non-uniform mutation operator whole non-uniform mutation operator) to explore whole search spaces, and four crossover operators(simple crossover operator, two-point crossover operator, arithmetic crossover operator, heuristic crossover operator) to exploit food characteristics of the best chromosome in previous generations. A case study and a sensitivity analysis have shown that the eight problem-specific operators developed for optimizing highway alignments enhance the search performance of genetic algorithms, and find good solutions(highway alignment alternatives). It has been also found that a mixed and well-combined use of mutation and crossover operators is very important to balance between pre-matured solutions when employing more crossover operators and more computation time when adopting more mutation operators.

• Journal of Preventive Medicine and Public Health
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• v.55 no.3
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• pp.289-296
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• 2022

Objectives: Integrating retail and manufacturing enables limitless potential for food businesses, but also creates challenges for navigating within complex food safety regulations. From public health inspectors' (PHIs) perspective, this study aimed (1) to describe the characteristics of crossover businesses in Louisiana, and (2) to evaluate regulation awareness and food safety education needs for business owners and PHIs who inspect crossover businesses. Methods: A self-administered questionnaire was administered to Louisiana Department of Health PHIs using Qualtrics^®. A descriptive analysis was performed, focusing on the frequency of each item. Results: In total, 1774 retailers were conducting or planned to conduct specialized processes, while 552 food manufacturers were performing or planned to perform retail functions. Reduced oxygen packaging, the use of additives such as vinegar as a method of preservation, and smoking food as a method of preservation were observed by 62%, 36%, and 35% of the PHIs, respectively. The PHIs perceived crossover businesses as "not aware" or "somewhat aware" of the food safety regulations. The current food safety training level for these businesses was reported to range from "no training" to "some training but not sufficient." When asked for a self-assessment, the majority of PHIs reported themselves as being "familiar" with the variance requirement for specialized processing. Their confidence in inspecting crossover businesses, however, leaned towards "not confident" or "somewhat confident." Conclusions: To better guard public health, food safety training is needed for crossover food business owners, as well as PHIs, on regulations and conducting or inspecting specialized processes.

• Proceeding of EDISON Challenge
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• 2013.04a
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• pp.37-52
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• 2013

무어의 법칙에 따르면, 반도체의 집적도 2년마다 2배씩 증가한다고 한다. 무어의 법칙은 지금까지는 집적회로 기술의 발전을 잘 예측했다. 하지만 트랜지스터의 사이즈를 줄일수록 누수전류와 회로의 저항을 조절하기 어렵기 때문에 트랜지스터의 소형화에는 한계가 있다. 우리는 곧 무어의 법칙의 한계를 맞이할 것이다. 그래서 트랜지스터를 더욱 소형화시키기 위해서는 bottom-up analysis가 필요한 시점이다. Top-down analysis가 초기의 커다란 트랜지스터에서 점점 소형화를 시켜 작은 트랜지스터를 만든다는 개념인 반면, Bottom-up analysis는 처음부터 작은 분자를 조작하여 트랜지스터와 같은 성질을 띄도록 만드는 개념이다. 분자가 기억소자로서 이용되려면 저항이 다른 2가지 안정한 상태가 필요하다. 이번 연구에서 나는 기억소자를 디자인 하기 위하여 high spin state와 low spin state 두 가지 안정한 상태를 가지는 spin crossover complex를 이용하기로 했다. 이전의 연구에서 spin crossover 는 전기장을 이용해서도 유도될 수 있다고 확신하였고, 이를 이용해서 기억소자를 디자인하기로 하였다. 이번 연구를 위해서 symmetry를 가지는 octahedral spin crossover complex를 디자인하였고 이를 '기억 분자'라고 명명했다. 그리고 이 분자의 high spin state와 low spin state가 전기장을 이용하여 서로 바뀔 수 있는지 가능성을 DFT with B3LYP functional을 이용해서 비교했다. 그 결과로 전기장을 이용하여 기억분자의 spin crossover을 일으킬 수는 있지만 abnormally strong electric field를 써야 한다는 사실을 알아냈다. 이번 연구를 토대로 추후의 연구를 위해, 기억소자가 되기 위하여 분자가 어떤 특징을 만족시켜야 하는지를 분석했다.

• International journal of advanced smart convergence
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• v.11 no.4
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• pp.104-119
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• 2022

Life safety awareness level diagnosis is necessary for customized safety education and continuous safety awareness. As the starting stage of safety education for each life cycle, a scale that has verified the reliability and validity of high school students' life safety awareness has not yet been developed. In this context, the purpose of this study is to develop and validate the life safety awareness scale of high school students and to analyze interindividual differences. Questionnaire data was collected from April to June 2022 from 834 students in the first, second, and third grades of high schools in △△ city in Jeollabuk-do. A final 25-item scale was developed using the preliminary survey, preliminary test, the main test, descriptive statistical analysis, and exploratory and confirmatory factor analysis. This scale consists of four sub-factors: 'safety prevention', 'safety knowledge', 'safety preparation', and 'safety protection'. Good reliability and validity were verified by analysis of content validity and construct validity. The generalizability of the scale was verified by crossover validation between the search group and the crossover group. Based on the interindividual differences analysis, although there was a difference between genders in life safety awareness, there was no difference by grade level and academic achievement. This study is significant in developing the first valid scale that can measure high school students' life safety awareness and providing the necessity and rationale for life safety education by life cycle considering individual gender differences.