• Journal of Korea Water Resources Association
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• v.46 no.6
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• pp.643-653
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• 2013

The most important procedure in frequency analysis is to determine the appropriate probability distribution and to estimate quantiles for a given return period. To perform the frequency analysis, the goodness-of-fit tests should be carried out for judging fitness between obtained data from empirical probability distribution and assumed probability distribution. The previous goodness-of-fit could not consider enough extreme events from the recent climate change. In this study, the critical values of the modified Anderson-Darling test statistics were derived for 3-parameter Weibull distribution and power test was performed to evaluate the performance of the suggested test. Finally, this method was applied to 50 sites in South Korea. The result shows that the power of modified Anderson-Darling test has better than other existing goodness-of-fit tests. Thus, modified Anderson-Darling test will be able to act as a reference of goodness-of-fit test for 3-parameter Weibull model.

• Journal of Ecology and Environment
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• v.43 no.4
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• pp.427-437
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• 2019

Background: Climate change is believed to be continuously affecting ticks by influencing their habitat suitability. However, we attempted to model the climate change-induced impacts on future genus Rhipicephalus distribution considering the major environmental factors that would influence the tick. Therefore, 50 tick occuance points were taken to model the potential distribution using maximum entropy (MaxEnt) software and 19 climatic variables, taking into account the ability for future climatic change under representative concentration pathways (RCPs) 4.5 and 8.5, were used. Results: MaxEnt model performance was tested and found with the AUC value of 0.99 which indicates excellent goodness-of-fit and predictive accuracy. Current models predict increased temperatures, both in the mid and end terms together with possible changes of other climatic factors like precipitation which may lead to higher tick-borne disease risks associated with expansion of the range of the targeted tick distribution. Distribution maps were constructed for the current, 2050, and 2070 for the two greenhouse gas scenarios and the most dramatic scenario; RCP 8.5 produced the highest increase probable distribution range. Conclusions: The future potential distribution of the genus Rhipicephalus show potential expansion to the new areas due to the future climatic suitability increase. These results indicate that the genus population of the targeted tick could emerge in areas in which they are currently lacking; increased incidence of tick-borne diseases poses further risk which can affect cattle production and productivity, thereby affecting the livelihood of smallholding farmers. Therefore, it is recommended to implement climate change adaptation practices to minimize the impacts.

• Journal of the Korean Data and Information Science Society
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• v.21 no.2
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• pp.219-229
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• 2010

There have been many researches on the risk management due to rapid increase of various risk factors for financial assets. Aa a method for comprehensive risk management, Value at Risk (VaR) is developed. For estimation of VaR, it is important task to solve the problem of asymmetric distribution of the return rate with heavy tail. Most real distributions of the return rate have high positive kurtosis and low negative skewness. In this paper, some alternative distributions are used to be fitted to real distributions of the return rate of financial asset. And estimates of VaR obtained by using these fitting distributions are compared with those obtained from real distribution. It is found that normal mixture distribution is the most fitted where its skewness and kurtosis of practical distribution are close to real ones, and the VaR estimation using normal mixture distribution is more accurate than any others using other distributions including normal distribution.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.11
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• pp.1272-1279
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• 2012

In this paper, models for the average-year rain rate distribution and the correlation between the worst-month and the average-year rain rate distribution in domestic environment were proposed, using the rainfall measurement data with 1-minute integration time of Korea Meteorological Administration. Comparison of the proposed model with the existing ITU-R model showed that the average rain rate of the proposed model for the exceed time rate of 0.01 % is about 28 % higher than that of the ITU-R recommendation. In addition, the correlation model between the worst-month and the average-year rain rate distribution was quite different from the ITU-R model. It is recommended that the domestic rain rate distribution model should be used for calculation of the statistical characteristics of rain attenuation(exceeded-time-rate distribution of rain attenuation) which is essential for the design of wireless communication systems in domestic environment.

• Journal of the Korea Safety Management & Science
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• v.13 no.2
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• pp.157-167
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• 2011

Currently, interest on physical distribution is increasing due to burden of oil cost increases as oil price rises day by day. As interest grows, there are number of studies have been conducting on saving the cost of distribution. On the other hand, number of study on service of distribution is insufficient. Actually, subject of service of physical distribution have been studied by number of survey organizations, research organizations and mass media. Although, configuration for each organization is different from each other and it is hard to measure objective satisfactory factor of customers. This means needs for constructing standardized measuring tool as well as research on measuring service quality of distribution is not active. Therefore, this research is to compare and analyze compatibility of service quality measuring using SERVQUAL and SERVPERF and trying to clarify differences affected by importance service quality by each level to actual service quality. Also, this research is to make basic and standardized measuring model to improve quality of physical distribution especially using analysis of service quality and customer satisfaction of pallet pool service which contributes rationalization of distribution and reduce the cost by standardizing specification and size of pallet, allowing sharing of pallet. To conduct this research, case study of a company A is used where it is in a pallet pool business. Using this example, the goal is to give help on pallet pool business a strategic exercise if the business by point out major factors that affect customer satisfaction by collecting customer assessment along with examination of SERVQUAL and SERVPERF in measuring service quality if pallet pool service.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.22 no.6
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• pp.639-646
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• 2009

High-flow steel-fiber reinforced mortar may induce a certain fiber orientation distribution in the process of placing and thus have an influence on the tensile properties. In this paper, the variation of the fiber orientation distribution according to the flow of high-flow steel-fiber reinforced mortar was estimated in numerical simulation. The analytical results present that the major variation of fiber orientation distribution is made within 150mm of flow distance, thereafter the tendency of the fiber orientation distribution is not noticeable even though the peak of distribution density in the orientation parallel to the flow direction get bigger along the distance. Considering the close relation between the fiber orientation and the tensile behavior of composite, prediction of fiber orientation distribution make it possible to predict the variation in the tensile behavior of high-flow steel-fiber reinforced mortar according to the flow.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39C no.11
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• pp.1050-1067
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• 2014

CAS(Close Air Support) is aircraft attack against hostile targets that are in close proximity to friendly forces. Immediate CAS is the mission that attack unplanned targets, and especially the distribution of suitable aircraft assets makes huge effect on the result of immediate CAS mission. But It is hard to find a previous studies on immediate CAS sortie distribution with aircraft suitability. This study suggests a methodology with aircraft suitability for immediate CAS sortie distribution. The methodology consists of 3 steps. Firstly, we analyze target information for situational awareness. Secondly, we calculate each aircraft's suitability value per each target based on the result of previous analysis. Lastly, we suggest immediate CAS sortie distribution based on the aircraft adoptability value to a decision maker. This methodology will provide not only quantitative analysis, but also decision making of immediate CAS sortie distribution more timely and effectively.

• Journal of the Korean Data and Information Science Society
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• v.22 no.6
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• pp.1175-1182
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• 2011

In this paper, properties of exact confidence interval and some approximate confidence intervals of hyper-geometric parameter, that is the probability of success p in the population is discussed. Usually, binomial distribution is a well known discrete distribution with abundant usage. Hypergeometric distribution frequently replaces a binomial distribution when it is desirable to make allowance for the finiteness of the population size. For example, an application of the hypergeometric distribution arises in describing a probability model for the number of children attacked by an infectious disease, when a fixed number of them are exposed to it. Exact confidence interval estimation of hypergeometric parameter is reviewed. We consider the approximation of hypergeometirc distribution to the binomial and normal distribution respectively. Approximate confidence intervals based on these approximation are also adequately discussed. The performance of exact confidence interval estimates and approximate confidence intervals of hypergeometric parameter is compared in terms of actual coverage probability by small sample Monte Carlo simulation.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.10
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• pp.84-88
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• 2008

This paper deals with the part of the surge protection method of the underground distribution system in Korea using arrestors by simulating with ATP-EMTP(Electro-Magnetic Transient Program) based on the "A Study on the Surge Propagation Property of Underground Distribution Cables by Field Tests" which was published in 2007. Although domestic underground distribution system is protected by arrester which installed at a riser pole, we need to additional protection method because lightning surge can be doubled and affect underground distribution facilities when it is injected into the mixed distribution line of overhead and underground through a riser pole. In this paper, it is proposed that scout method that arresters are attached to the sides of a riser pole is better than developing of a elbow arrester on a viewpoint of economics and maintenance, because of the situation of the domestic underground distribution system.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.11
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• pp.4718-4725
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• 2011

Intake-air flow and distribution characteristics of the 1600cc gasoline engine intake manifold have been studied using the computer simulation. Simulation has been conducted using both one-dimensional performance simulation and three-dimensional CFD software. Steady state flow simulation result of the intake manifold shows good distribution characteristics that the standard deviation of flow coefficients is below 1.0 percentage for both one- and three-dimensional simulation. Even though one-dimensional simulation result slightly overestimates compared with three-dimensional simulation result, both results show very good agreement in flow coefficient trend. Also, unsteady state simulation result shows consistent distribution characteristics with that of steady state. It is shown that unsteady state distribution characteristics might be able to be predicted through the steady state mass distribution result.