• The Journal of Fisheries Business Administration
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• v.46 no.1
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• pp.93-107
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• 2015

This study aims to analyze causalities among Hairtail prices by distribution channel using a vector autoregressive model. This study applies unit-root test for stability of data, uses Granger causality test to know interaction among Hairtail Prices by distribution channel, and employes the vector autoregressive model to estimate statistical impacts among t-2 period variables used in model. Analyzing results of this study are as follows. First, ADF, PP, and KPSS tests show that the change rate of Hairtail price by distribution channel differentiated by logarithm is stable. Second, a Granger causality test presents that the producer price of Hairtail leads the wholesale price and then the wholesale price leads the consumer price. Third, the vector autoregressive model suggests that the change rate of Hairtail producer price of t-2 period variables statistically, significantly impacts change rates of own, wholesale, and consumer prices at current period. Fourth, the impulse response analysis indicates that impulse responses of the structural shocks with a respectively distribution channel of the Hairtail prices are relatively more powerful in own distribution channel than in other distribution channels. Fifth, a forecast error variance decomposition of the Hairtail prices points out that the own price has relatively more powerful influence than other prices.

• Journal of Power System Engineering
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• v.17 no.4
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• pp.86-93
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• 2013

This paper deals with the effects of driving force and material properties on statistical distribution of fatigue crack growth rate (FCGR) for the friction stir welded joints of Al 7075-T651 aluminum plate. In this work, the statistical probability distribution of fatigue crack growth rate was analyzed by using our previous constant stress intensity factor range controlled fatigue crack growth test data. As far as this study are concerned, the statistical probability distribution of fatigue crack growth rate for the friction stir welded (FSWed) joints was found to evaluate the variability of fatigue crack growth rate for base metal (BM), heat affected zone (HAZ) and weld metal (WM) specimens. The probability distribution of fatigue crack growth rate for FSWed joints was found to follow well log-normal distribution. The shape parameter of BM and HAZ was decreased with increasing the driving force, however, the shape parameter of WM was decreased and increased with increasing the driving force. The scale parameter of BM, HAZ and WM was increased with the driving force.

• Journal of Applied Reliability
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• v.17 no.4
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• pp.332-342
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• 2017

Purpose: In this study, the lifetime distribution of a k-out-of-n system with heterogeneous components is suggested as Markov model, and the time-to-failure (TTF) distribution of each component is considered as phase-type distribution (PHD). Furthermore, based on the model, a redundancy allocation problem with a mix of components (RAPMC) is proposed. Methods: The lifetime distribution model for the system is formulated by the structured Markov chain. From the model, the various information on the system lifetime can be ascertained by the matrix-analytic (or-geometric) method. Conclusion: By the generalization of TTF distribution (PHD) and the consideration of heterogeneous components, the lifetime distribution model can delineate many real systems and be exploited for developing system operation policies such as preventive maintenance, warranty. Moreover, the effectiveness of the proposed RAPMC is verified by numerical experiments. That is, under the equivalent design conditions, it presented a system with higher reliability than RAP without component mixing (RAPCM).

• Journal of Integrative Natural Science
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• v.14 no.3
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• pp.123-129
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• 2021

This research examines the effect of positively skewed population distribution on the two sample t-test through simulation. For simulation work, two independent samples were selected from the same chi-square distributions with 3, 5, 10, 15, 20, 30 degrees of freedom and sample sizes 3, 5, 10, 15, 20, 30, respectively. Chi-square distribution is largely skewed to the right at small degrees of freedom and getting symmetric as the degrees of freedom increase. Simulation results show that the sampled populations are distributed positively skewed like chi-square distribution with small degrees of freedom, the F-test for the equality of variances shows poor performances even at the relatively large degrees of freedom and sample sizes like 30 for both, and so it is recommended to avoid using F-test. When two population variances are equal, the skewness of population distribution does not affect on the t-test in terms of the confidence level. However even though for the highly positively skewed distribution and small sample sizes like three or five the t-test achieved the nominal confidence level, the error limits are very large at small sample size. Therefore, if the sampled population is expected to be highly skewed to the right, it will be recommended to use relatively large sample size, at least 20.

• Communications for Statistical Applications and Methods
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• v.28 no.5
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• pp.425-445
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• 2021

A generalization of the log-logistic (LL) distribution called exponentiated log-logistic (ELL) distribution on lines of exponentiated Weibull distribution is considered. In this paper, based on progressive type-II censored samples, we have derived the maximum likelihood estimators and Bayes estimators for three parameters, the survival function and hazard function of the ELL distribution. Then, under the balanced squared error loss (BSEL) and the balanced linex loss (BLEL) functions, their corresponding Bayes estimators are obtained using Lindley's approximation (see Jung and Chung, 2018; Lindley, 1980), Tierney-Kadane approximation (see Tierney and Kadane, 1986) and Markov Chain Monte Carlo methods (see Hastings, 1970; Gelfand and Smith, 1990). Here, to check the convergence of MCMC chains, the Gelman and Rubin diagnostic (see Gelman and Rubin, 1992; Brooks and Gelman, 1997) was used. On the basis of their risks, the performances of their Bayes estimators are compared with maximum likelihood estimators in the simulation studies. In this paper, research supports the conclusion that ELL distribution is an efficient distribution to modeling data in the analysis of survival data. On top of that, Bayes estimators under various loss functions are useful for many estimation problems.

• Journal of Distribution Science
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• v.21 no.9
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• pp.67-79
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• 2023

Purpose: To investigate the intensity of bilateral international trade of the Silk Road Economic Belt (SREB) countries with Kazakhstan, its relationship with logistics (LPI), to assess their contribution to economic growth and distribution of commodity flows. Research design, data, and methodology: The method of analyzing the bilateral trade flow was applied by using the trade intensity index (TII) and a multidimensional regression model describing the relationship between LPI and its components, TII, the volume of exports and imports, GDP. Results: The nature and directions of the relationship between TII and the key components of logistics, the positive impact of LPI on the intensity of trade are established. It is revealed that the intensity of trade between the countries in the direction of the EAEU-Kazakhstan has a greater impact on the growth of LPI than in the opposite direction. At the same time, the higher the level of trade integration and the volume of GDP, the stronger their impact on the efficiency of logistics and distribution of commodity flows. Conclusions: Effective distribution of commodity flows will require the development of logistics components based on the direction of bilateral trade and the size of countries, the intensification of state reforms in the field of international trade and distribution logistics.

• Fourth Industrial Review
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• v.1 no.2
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• pp.9-16
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• 2021

Purpose - O2O (online to off-line) is a new economic concept being emerged in the 4^th industrial age. Automobile distribution is also undergoing a change to the O2O system. In overseas, vehicles are already being sold through various online platforms. The purpose of this study is to analyze the domestic and foreign automobile distribution structure and intends to suggest the desirable direction of automobile sales in the 4th industrial age. Research design, data, and methodology - Through the investigation of previous studies and the actual cases, the advantages and disadvantages and trends of different types of automobile distribution structures. Result - It can be seen that domestic and foreign automobile brands have quite diverse distribution structures such as direct managed system, agency system, dealer system, direct sales system, online system and online/offline parallel system. Each type has its own characteristics. Conclusion - The distribution structure of automobiles is very diverse, and in particular, it is rapidly changing to an online sales system thanks to the development of information and communication technology and Internet technology and the popularization of smartphones. Through the online system, consumers can quickly and conveniently obtain vehicle information. Although the online sales system has many advantages, it requires continuous management

• Fourth Industrial Review
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• v.2 no.1
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• pp.1-8
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• 2022

Purpose - O2O (online to off-line) is a new economic concept being emerged in the 4^th industrial age. Automobile distribution is also undergoing a change to the O2O system. In overseas, vehicles are already being sold through various online platforms. The purpose of this study is to analyze the domestic and foreign automobile distribution structure and intends to suggest the desirable direction of automobile sales in the 4th industrial age. Research design, data and methodology - Through the investigation of previous studies and the actual cases, the advantages and disadvantages and trends of different types of automobile distribution structures. Result - It can be seen that domestic and foreign automobile brands have quite diverse distribution structures such as direct managed system, agency system, dealer system, direct sales system, online system and online/offline parallel system. Each type has its own characteristics. Conclusion - The distribution structure of automobiles is very diverse, and in particular, it is rapidly changing to an online sales system thanks to the development of information and communication technology and Internet technology and the popularization of smartphones. Through the online system, consumers can quickly and conveniently obtain vehicle information. Although the online sales system has many advantages, it requires continuous management.

• Nuclear Engineering and Technology
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• v.55 no.12
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• pp.4678-4684
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• 2023

Using the Monte Carlo method, the impact of the angular distribution of the electron source on the dose distribution for the 2.5 MeV ELV electron accelerator was explored. The experiment measured the 3-D dose distribution in the irradiation chamber for electron energies of 1.0 MeV and 2.5 MeV. The simulation used the MCNP6.2 code to evaluate three angular distribution models of the source: a mono-directional beam, a cone shape, and a triangular shape. Of the three models, the triangular shape with angles θ = 30°, φ = 0° best represents the angle of the scan hood through which the electron beam exits. The MCNP6.2 simulation results demonstrated that the triangular model is the most accurate representation of the angular distribution of the electron source for the 2.5 MeV ELV electron accelerator.

• Kyungpook Mathematical Journal
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• v.23 no.2
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• pp.203-212
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• 1983