• Journal of the Korean Statistical Society
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• 제29권2호
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• pp.155-168
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• 2000

Regarding to multiple comparison problem (MCP) of k normal population variances, we suggest a Bayesian method for calculating posterior probabilities for various hypotheses of equality among population variances. This leads to a simple method for obtaining pairwise comparisons of variances in a statistical experiment with a partition on the parameter space induced by equality and inequality relationships among the variances. The method is derived from the fact that certain features of the hierarchical nonparametric family of Dirichlet process priors, in general, make it amenable to solving the MCP and estimating the posterior probabilities by means of posterior simulation, the Gibbs sampling. Two examples are illustrated for the method. For these examples, the method is straightforward for specifying distributionally and to implement computationally, with output readily adapted for required comparison.

• 대한안전경영과학회지
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• 제15권2호
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• pp.217-221
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• 2013

I suggest a new method to determine the importance values of quality attributes which use the satisfaction index and dissatisfaction index of customer in Kano's model. A case study of TV set are solved by the proposed method and the result is compared with AHP pairwise comparisons and ASC(Average Satisfaction Coefficient). The results of the proposed method is similar with those of AHP pairwise comparisons and ASC. The proposed method is an effective tool to determine the importance values of quality attributes to supplement existing research's shortcomings.

• 대한교통학회지
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• 제14권2호
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• pp.89-118
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• 1996

The development and implementation of a real-time, traffic adaptive control scheme based on fuzzy logic through Video Image Detector systems (VIDs) is presented. Through VIDs based image processing, fuzzy logic can be used for a real-time traffic adaptive signal control scheme. Fuzzy control logic allows linguistic and inexact traffic data to be manipulated as a useful tool in designing signal timing plans. The fuzzy logic has the ability to comprehend linguistic instructions and to generate control strategy based on a priori verbal communication. The implementation of fuzzy logic controller for a traffic network is introduced. Comparisons are made between implementations of the fuzzy logic controller and the actuated controller in an isolated intersection. The results obtained from the application of the fuzzy logic controller are also compared with those corresponding to a pretimed controller for the coordinated intersections. Simulation results from the comparisons indicate the performance of the system is between under the fuzzy logic controller. Integration of the aforementioned schemes into and ATMS framework will lead to real-time adjustment of the traffic control signals, resulting in significant reduction in traffic congestion.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 1997년도 춘계학술대회논문집; 경주코오롱호텔; 22-23 May 1997
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• pp.669-674
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• 1997

A sound field in a reverberation room is analyzed by using numerical methods and the SPL distributions are compared to the measurements. In numerical predictions, the BEM is employed in the low frequency range, while sound ray tracing method is used for the high frequency range. In the BEM analysis, the surfaces of the empty reverberation room are assumed as rigid boundaries and the damping coefficients are estimated from the measured absorption coefficient. The comparisons with measurements for 100Hz shows good agreement. In the sound ray tracing analysis, the predicted energy decay are in excellent agreements with theoretical results. It is shown that the energy absorption by air damping plays an important role as frequency becomes higher.

• 한국가정과교육학회지
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• 제8권2호
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• pp.15-28
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• 1996

The purpose of this study is to investigate the family life participation and to analysis its related variables focusing on comparisons of male and female in the secondary students. The questonaire included school environmental variables, family environmental variables, the preference degree of Home Economics, sex role attitudes and the family life participation. The participants were 600 middle and high school students but the final data used on this study were 559. For the statistical analysis of this study, fequency, mean, Cronbach’s ${\alpha}$ coefficient, one way ANOVA, t-test and multiple regression were calculated. The results of this study were summarized as follows；1) The degree of family life participation was a little higher than middle level. While the highest participation degree was family activities participation, the participation degree of household work, communication and decision-making, leisure activities were low. 2) The variables that influence on the family life participation were the level of living and preference degree of Home Economics for both male and female.

• International Journal of Aeronautical and Space Sciences
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• 제11권1호
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• pp.41-48
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• 2010

In the present study, the turbulent flow fields around a circular cylinder at $Re=3.6{\times}10^6$ were investigated based on an unstructured mesh technique, and the comparisons between URANS(S-A, SST) and hybrid RANS/LES(DES, SAS) methods for the simulation of high Reynolds number flow have been conducted. For this purpose, unsteady characteristics of vortex shedding and time-averaged quantities were compared. A quasi-steady solution-adaptive mesh refinement was also made for the URANS and hybrid RANS/LES approaches. The results showed that the simple changes in the turbulent length scale or source term of turbulent models made the flow fields less dissipative and more realistic in hybrid RANS/LES methods than the URANS approaches.

• The Korean Journal of Ecology
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• 제14권1호
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• pp.113-117
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• 1991

Comparisons of the physico-chemical properties of earthworm(Lumbricus terrestris) soil casts and top soil of red pine forests in a limestone area were carried out. The casts production durign August and September in 1990 amounted to 6∼7t/ha. The particle of top soil and casts ranged 40∼50% and 10∼20% for sand , 25∼30% and 30∼35% for silt, and 20∼25% and 55∼65% clay, respectively. Significant difference in pH value was not observed between casts and top soil. The casts had 1.4times of organic matter, 1.5times of N, 1.8times of available P, 2times of exchangeable K, 1.3times of exchangeable Ca, and 1.6times of exchangeable Mg than the top 10cm of soil did. Earthworms have altered the soil texture and increased nutrient availability through production of the soil casts in this limestone area.

• Structural Engineering and Mechanics
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• 제5권1호
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• pp.51-58
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• 1997

The influence of bi-directional earthquake-induced loading on eccentric (plan-asymmetric) building systems has been investigated. In the first part of the study, comparisons have been made with equivalent results from uni-directional studies. The results are important in developing analytical models appropriate to the formulation of design recommendations. It is concluded that for valid comparisons, both perpendicular horizontal earthquake components must be considered when using models with transversely-orientated elements. In the second part of the study, an assessment has been made of a simplified, unidirectional (lateral) design approach. For stiffness-eccentric systems, the latter approach gives accurate and reasonably conservative estimates of the critical flexible-edge deformation, but may under estimate the stiff-edge element ductility demand by a factor of two in the short-period range.

• Nuclear Engineering and Technology
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• 제52권11호
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• pp.2499-2510
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• 2020

We performed 3-D (3-dimensional) IVR (In-Vessel Retention) natural convection experiments simulating the oxide layer in the three-layer configuration, varying the aspect ratio (H/R). Mass transfer experiment was conducted based on the analogy to achieve high Ra_H's of 1.99 × 10¹²-6.90 × 10¹³ with compact facilities. Comparisons with 2-D (2-dimensional) experiments revealed different local heat transfer characteristics on upper and lower boundaries of the oxide layer depending on the H/R. For the 3-D shallow oxide layer, the multi-cell flow patterns appeared and the number of cells was considerably increased with the H/R decreases, which differs with the 2-D experiments that the number of cells was independent on H/R. Thus, the enhancement of the downward heat transfer and the mitigation of the focusing effect were more noticeable in the 3-D experiments.

• 멤브레인
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• 제3권1호
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• pp.35-39
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• 1993

역삼투 및 투과 증발막 분리공정이 nylon 4 blended 막을 사용하여 물-에탄올 계에 대하여 실험적으로 비교되어졌다. 위 두 공저의 이론적 비교를 다루었던 전 논문과 마찬가지로 투과 증발 공정의 분리 효율이 역삼투 공저의 경우 보다 더 좋음을 알 수 있었다. 그러나 투과도 데이타는 막의 결함들로 인하여 엉뚱한 결과를 보였다.