• Proceedings of the Korea Water Resources Association Conference
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• 2004.05b
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• pp.1103-1106
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• 2004

The objective of this study is to induce the design drought rainfall by the methodology of L-moment including testing homogeneity, independence and outlier of the data of annual minimum monthly rainfall in 57 rainfall stations in Korea in terms of consecutive duration for 1, 2, 4, 6, 9 and 12 months. To select appropriate distribution of the data for annual minimum monthy rainfall by rainfall station, the distribution of generalized extreme value (GEV), generalized logistic (GLO) as well as that of generalized pareto (GPA) are applied and the appropriateness of the applied GEV, GLO, and GPA distribution is judged by L-moment ratio diagram and Kolmogorov-Smirnov (K-S) test. As for the annual minimum monthly rainfall measured by rainfall station and that stimulated by Monte Carlo techniques, the parameters of the appropriately selected GEV and GPA distributions are calculated by the methodology of L-moment and the design drought rainfall is induced. Through the comparative analysis of design drought rainfall induced by GEV and GPA distribution by rainfall station, the optimal design drought rainfall by rainfall station is provided.

• Journal of Korea Water Resources Association
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• v.40 no.9
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• pp.735-742
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• 2007

In this study, a methodology which is based on segments and minimum outsets to estimate the reliability of a real water distribution system efficiently and accurately is suggested. The current reliability assessment models based on minimum cutset consider a pipe as only area impacted by a pipe failure which incurs underestimation of pipe failure impact. In contrary, the suggested methodology adopts "segment" and "unintended isolation" with the hydraulic pressure failure area to define the actual service interruption area in a water distribution system due to a pipe failure, which is different from the Previous reliability estimating methodologies. In addition, a minimum cutset is defined as a single segment incurring abnormal operating conditions and the success mode approach is used to account for the probability of multiple failure combinations of minimum outsets. The model considers numbers and locations of on-off valves when the service interruption area is defined. Once the methodology is applied to a real water distribution system, it is possible to define actual service interruption areas and using the defined areas, the reliability of the water distribution system is estimated reliably, compared with the previous reliability assessment methodologies.

• Journal of Korean Institute of Industrial Engineers
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• v.21 no.3
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• pp.313-327
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• 1995

This paper deals with ordering policies for a multi-echelon distribution system. The system we are concerned consists of one Central Distribution Center(CDC) and N nonidentical Regional Distribution Centers(RDCs) which have different demand rates, minimum filtrates, leadtimes, etc. We develop an algorithm for determining the optimal ordering policies of the CDC and the RDCs under the constraints of minimum filtrates of RDCs and maximum allowable delay of CDC.

• Magazine of the Korean Society of Agricultural Engineers
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• v.34 no.3
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• pp.43-52
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• 1992

Design low flows were derived from the decision of a best fitting probability distribution and of an optimum transformation method can be contributed to the planning of water utilization and management of various hydraulic structures during dry season in the main river systems in Korea. The results were analyzed and summarized as follows. 1.Basic statistics for the selected watersheds were calculated as one of means for the analysis of extremal distribution. 2.Parameters for the different frequency distributions were calculated by the method of moment. 3.Type m extremal distribution was confirmed as a best one among others for the frequency distribution of the low flows by x$^2$ goodness of fit test. 4.Formulas for the design low flows of the Type m extremal distribution with two and three parameters were dervied for the selected watersheds. 5.Design low flows for the Type m extremal distribution when a minimum drought is zero or larger than zero were derived for the selected watersheds, respectively. 6.Design low flows of the Type m extremal distribution with two parameters are appeared to be reasonable when a minimum drought approaches to zero and the observed low flows varied within a relating small range while those with three parameters are seemed to be consistent with the probability distribution of low flows when a minimum drought is larger than zero and the observed low flows showed a wide range.

• The Journal of Industrial Distribution & Business
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• v.12 no.3
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• pp.31-41
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• 2021

Purpose: The purpose of this paper is to analyze the impact of the minimum wage policy and the employment labor force in Myanmar by exploring firms' actions such as installing supplementary machines to substitute for labor resources and by addressing gender issues in employment. Research design, data, and methodology: This paper applies a fixed-effect estimation method by using the World Bank's enterprise panel data set surveyed in Myanmar. Results: Findings suggest that the minimum wage reduces both full-time and part-time employment, while the first minimum wage policy increases overall female employment. The adverse impacts are more pronounced for female employees of Joint Venture enterprises and enterprises located in the less-populated regions. Investment in capital such as equipment and machinery increase to substitute for labor after the minimum wage policy implementation; as a result, full-time employment slightly decreases. Conclusions: Appropriate measures concerning the minimum wage policy must be prepared by the government and institutions related to the labor union to serve the well-being of employees. Government of Myanmar should fix the minimum wage in a reasonable period based on the fiscal year for both employers and employees to prevent possible issues and losses resulting from the minimum wage being set.

• East Asian Economic Review
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• v.24 no.3
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• pp.253-273
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• 2020

This paper investigates the impact of the effective minimum wage, defined as the log difference between the minimum and the median wages, on wage inequalities in the OECD countries. Unlike the previous studies that focus on single countries in which the minimum wage has no cross-sectional variation and rely instead on within-country variations of wage distribution across regions or socio-economic characteristics, we use a country panel that allows for both cross-sectional and time-series variations in minimum wage. We also control for more factors than in the previous studies whose absence may cause endogeneity. Our results confirm the previous findings that increases in minimum wage alleviate the wage inequality at the lower tail of the wage distribution, while having little effect at the upper tail. The estimated effect is larger for women than for men, which is consistent with the fact that the share of workers who are directly affected by the changes in minimum wage is bigger among women than men. An application of the IVs of Autor, Manning and Smith (2016) supports the robustness of our findings.

• Communications for Statistical Applications and Methods
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• v.13 no.3
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• pp.657-667
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• 2006

The concept of entropy, introduced in communication theory by Shannon (1948) as a measure of uncertainty, is of prime interest in information-theoretic statistics. This paper considers the minimum variance unbiased estimation for the maximum entropy of the transformed inverse Gaussian random variable by $Y=X^{-1/2}$. The properties of the derived UMVU estimator is investigated.

• IE interfaces
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• v.16 no.spc
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• pp.39-44
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• 2003

As one of many design variables, the role of dimension tolerances is to restrict the amount of size variation in a manufactured feature while ensuring functionality. In this study, a nonlinear integer model has been modeled to allocate the optimal tolerance to each individual feature at a minimum manufacturing cost. While a normal distribution determines statistically worst tolerances with its symmetrical property in many previous tolerance allocation studies, a asymmetrical distribution is more realistic because its mean is not always coincident with a process center. A nonlinear integer model is modeled to allocate the optimal tolerance to a feature based on a beta distribution at a minimum total cost. The total cost as a function of tolerances is defined by machining cost and quality loss. After the convexity of manufacturing cost is checked by the Hessian matrix, the model is solved by the Complex Method. Finally, a numerical example is presented demonstrating successful model implementation for a nonlinear design case.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.53 no.10
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• pp.565-572
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• 2004

This paper proposes an expert system which can enhance the accuracy of real-time bus reconfiguration strategy by adopting local minimum tree search method and minimize the spreading effect of the fault by considering totally the operating condition when a main transformer fault occurs in the automated substation. The local minimum tree search method to expand the best-first search method. This method has an advantage which can improve the performance of solution within the limits of the real-time condition. The inference strategy proposed expert system consists of two stages. The first stage determines the switching candidate set by searching possible switching candidates starting from the main transformer or busbar related to the event. And, second stage determines the rational real-time bus reconfiguration strategy based on heuristic rules for the obtained switching candidate set. Also, this paper studies the generalized distribution substation modelling using graph theory and a substation database is designed based on the study result. The inference engine of the expert system and the substation database is implemented in MFC function of Visual C++. Finally, the performance and effectiveness of the proposed expert system is verified by comparing the best-first search solution and local minimum tree search solution based on diversity event simulations for typical distribution substation.

• Journal of the Korean Data and Information Science Society
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• v.22 no.6
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• pp.1217-1222
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• 2011

In this paper, we show that any circular density can be closely approximated by an exponential family of distributions. Therefore we propose an exponential family of distributions as a new family of circular distributions, which is absolutely suitable to model any shape of circular distributions. In this family of circular distributions, the trigonometric moments are found to be the uniformly minimum variance unbiased estimators (UMVUEs) of the parameters of distribution. Simulation result and goodness of fit test using an asymmetric real data set show usefulness of the novel circular distribution.