• 제목/요약/키워드: Empirical studies

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실험적 용량산정 방법 비교 연구 (Comparing Empirical Methods of Highway Capacity Estimation)

  • 문재필;조원범
    • 한국도로학회논문집
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    • 제16권1호
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    • pp.57-62
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    • 2014
  • PURPOSES : Capacity is a main factor of determining the number of lane in highway design or the level of service in road on operation. Previous studies showed that breakdown may occur before capacity is reached, and then it was concluded that capacity is a stochastic value rather than a deterministic one. In general, estimating capacity is based on average over maximum traffic volume observed for capacity state. This method includes the empirical distribution method(EDM) and would underestimate capacity. This study estimated existing empirical methods of estimating stochastic highway capacity. Among the studied methods are the product limit method(PLM) and the selected method(SM). METHODS : Speed and volume data were collected at three freeway bottleneck sites in Cheonan-Nonsan and West Sea Freeway. The data were grouped into a free-flow state or capacity state with speeds observed in the bottlenecks and the upstream. The data were applied to the empirical methods. RESULTS : The results show that the PLM and SM estimated capacity higher than EDM. The reason is that while the EDM is based on capacity observations only, the PLM and SM are based on free-flow high volumes and capacity observations. CONCLUSIONS : The PLM and SM using both free-flow and capacity observations would be improved to enhance the reliability of the capacity estimation.

수치 시뮬레이션 방법을 이용한 어업실습선 백경호의 조종성 추정 (Estimation of maneuverability of fisheries training vessel BAEK-KYUNG using numerical simulation method)

  • 김수형;이춘기;이유원
    • 수산해양기술연구
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    • 제57권3호
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    • pp.246-255
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    • 2021
  • Most fishing vessels are less than 100 m in length (LBP), which is not mandatory for the IMO standards for ship maneuverability. Therefore, research on estimating the maneuverability of fishing vessel hull shapes are somewhat lacking compared to that of merchant ship hull shapes, and at the design stage, the numerical simulation method developed for merchant ships are applied without modification to estimate the maneuverability. Since this can cause estimation errors, the authors have derived a modified empirical formula that can improve the accuracy of estimating the maneuverability of fishing vessels in a previous study. In this study, using the modified empirical formula, the IMO maneuverability evaluation items, the turning motion test and Z-test simulations were performed on the fisheries training vessel BAEK-KYUNG and compared with the sea trial test result to verify the validity of the modified empirical formula. In conclusion, the modified empirical formula was able to estimate quantitatively and qualitatively similar to the result of the sea trial test. Such a study on estimating the maneuverability of fishing vessels will be a good indicator for fishing vessel operators and will help them analyze marine accidents.

미얀마 노동자 의식의 실태와 조직몰입에 대한 영향 :제조업 생산직노동자의 경우 (The Reality and the Effect on Organizational Commitment of Myanmar Workers' Consciousness :A Case of Blue Collar Worker in Manufacturing Industry)

  • 윤영삼
    • 아태비즈니스연구
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    • 제10권3호
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    • pp.17-35
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    • 2019
  • This paper analyzes the reality of Myanmar workers' consciousness and reports the results of exploratory empirical studies that examined the influence of workers' consciousness on organizational commitment. To accomplish the purpose of the study, we performed conceptual and empirical research and mainly focused on empirical research through questionnaires on 262 workers in the manufacturing industry in Myanmar. Results of this empirical study are summarized as follow. First, the consciousness of the labor union of Myanmar labors such as 'Necessity of Union', 'Necessity of Strong Union', 'Militant Ideology' and 'Democracy' was high. The wage fair consciousness, which is a core consciousness related to the working conditions, is high, and class consciousness and collectivism, which are corporate and social consciousness, are also high but the 'growth ideology' and 'competitiveness ideology' are low. Second, the younger generation, less than high school graduates, and Yangon's workers have highly consciousness increasing the instability of industrial relations. Third, consciousness factors which have significant influence on organizational commitment were labor-management cooperation consciousness (+), democracy (-), competitiveness ideology (+), class consciousness (-) and authoritarianism (+). Lastly, implications and limitations of this empirical study, and suggestions for future research are suggested.

Application of CFD model for passive autocatalytic recombiners to formulate an empirical correlation for integral containment analysis

  • Vikram Shukla;Bhuvaneshwar Gera;Sunil Ganju;Salil Varma;N.K. Maheshwari;P.K. Guchhait;S. Sengupta
    • Nuclear Engineering and Technology
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    • 제54권11호
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    • pp.4159-4169
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    • 2022
  • Hydrogen mitigation using Passive Autocatalytic Recombiners (PARs) has been widely accepted methodology inside reactor containment of accident struck Nuclear Power Plants. They reduce hydrogen concentration inside reactor containment by recombining it with oxygen from containment air on catalyst surfaces at ambient temperatures. Exothermic heat of reaction drives the product steam upwards, establishing natural convection around PAR, thus invoking homogenisation inside containment. CFD models resolving individual catalyst plate channels of PAR provide good insight about temperature and hydrogen recombination. But very thin catalyst plates compared to large dimensions of the enclosures involved result in intensive calculations. Hence, empirical correlations specific to PARs being modelled are often used in integral containment studies. In this work, an experimentally validated CFD model of PAR has been employed for developing an empirical correlation for Indian PAR. For this purpose, detailed parametric study involving different gas mixture variables at PAR inlet has been performed. For each case, respective values of gas mixture variables at recombiner outlet have been tabulated. The obtained data matrix has then been processed using regression analysis to obtain a set of correlations between inlet and outlet variables. The empirical correlation thus developed, can be easily plugged into commercially available CFD software.

확산적 사고와 수렴적 사고: 좌뇌와 우뇌의 연관성 (Divergent and Convergent Thinking : The Connection of Right and Left-brain)

  • 이홍
    • 지식경영연구
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    • 제7권2호
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    • pp.1-11
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    • 2006
  • What is the role of right and left-brain in creative thinking? The current study is to address this question. Two empirical studies were performed to answer the question. First one is regarding the divergent thinking and right-brain connection. Second one is regrading the convergent thinking and left-brain connection. Empirical study showed that both of divergent and convergent thinking were asymmetrically related to creativity. Divergent thinking was connected to right-brain and convergent thinking was connected to left brain.

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결혼만족도 연구와 척도의 고찰을 통한 새로운 연구 방향과 척도의 모색 (Marital Relations: A Crithical Review and Development of Measurement)

  • 정현숙
    • 대한가정학회지
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    • 제35권1호
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    • pp.191-204
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    • 1997
  • Reserarch on marital satisfaction adjustment or quality has been one of the most frequently studies area of the investigation in the family field. Yet there has been many problems with the theory and empirical work in this area especially in the area of definitional ambiguity problems of dimensionality level of analysis and problems of measurement. This article is a critical review of this work including both theoretical and empirical problems that typically have occured with the previous research Also a section on suggested modifications for future research in this area and a section of suggestion of new marital satisfaction measurement are included.

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A Study on the Posterior Density under the Bayes-empirical Bayes Models

  • Sohn, Joong-K.Sohn;Kim, Heon-Joo-Kim
    • Communications for Statistical Applications and Methods
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    • 제3권3호
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    • pp.215-223
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    • 1996
  • By using Tukey's generalized lambda distribution, appoximate posterior density is derived under the Bayes-empirical Bayes model. The sensitivity of posterior distribution to the hyperprior distribution is examined by using Tukey's generalized lambda distriburion which approximate many well-knmown distributions. Based upon Monte Varlo simulation studies it can be said that posterior distribution is sensitive to the cariance of the prior distribution and to the symmetry of the hyperprior distribution. Also posterior distribution is approximately obtained by using the following methods : Lindley method, Laplace method and Gibbs sampler method.

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Bayesian small area estimations with measurement errors

  • Goo, You Mee;Kim, Dal Ho
    • Journal of the Korean Data and Information Science Society
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    • 제24권4호
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    • pp.885-893
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    • 2013
  • This paper considers Bayes estimations of the small area means under Fay-Herriot model with measurement errors. We provide empirical Bayes predictors of small area means with the corresponding jackknifed mean squared prediction errors. Also we obtain hierarchical Bayes predictors and the corresponding posterior standard deviations using Gibbs sampling. Numerical studies are provided to illustrate our methods and compare their eciencies.

임금만족 측정치 개발에 관한 실증적 연구 (A Empirical Study on the Developments of Pay Satisfaction Measurements)

  • 이광희
    • 산업경영시스템학회지
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    • 제23권54호
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    • pp.119-128
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    • 2000
  • This study develops the pay satisfaction questionnaire for Korean employees. Based upon the review of previous studies, 16 questionnaire items are developed. Exploratory factor analysis results in a modified measurement through item deletion, item-to-dimension reassignment, and dimension combination. The measurement model was good fit assessed by overall fit measures(GFI; goodness of fit index, AGFI; adjusted goodness of fit index, RMR; root mean square residual) criteria, lambda score, and squared multiple correlation with confirmatory factor analysis. Implication of this work for future theoretical and empirical development are suggested.

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A study on Customer satisfaction and Repurchase intention on Chinese Mobile service

  • SU, Shuai
    • 한국인공지능학회지
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    • 제7권1호
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    • pp.1-4
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    • 2019
  • This study to investigate Mobile service quality factors influencing on customer satisfaction and repurchase intention for the research purpose. This study collected data by a survey method for an empirical. A total of 340 replies were used for data analysis. While 340 replies were collected from Chinese users of Mobile e-commerce. Our results support previous researches to results of SPSS analysis all of the 7 hypotheses, 4 hypotheses are adopted and 3 are deleted. After an empirical analysis of this study, the academic implications are as follows. As there have not been many academic studies related to mobile commerce quality, this study can be a meaningful framework when quality factors associated with mobile commerce are being analyzed. This paper as the mobile commerce industry is very sensitive to environmental changes, academic research that can be used to cope with these changes is continuously required. Further studies should be carried out to overcome limitations that have not been analyzed by this study.