• Journal of the Korean Data and Information Science Society
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• 제25권5호
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• pp.1039-1055
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• 2014

검정통계량의 영가설 분포는 모집단 분포에 의존하는데 모집단의 분포를 모를 때 영가설 분포를 검정통계량의 조건부 분포로 대체하여 검정하는 방법을 순열 검정이라고 한다. Strasser와 Weber (1999)는 순열 검정을 통합하는 이론을 마련하였고, Hothorn 등 (2006, 2008)은 그 이론을 R에 내장된 coin 패키지에 구현하였다. coin 패키지에서 조건부 독립성 검정은 총괄적인 형태의 함수인 independence test를 통해서 할 수 있지만 대표적인 독립성 검정은 사용자가 편리하도록 간편한 함수를 별도로 제공하고 있다. 본 논문에서는 Strasser와 Weber (1999)의 순열 검정 방법에 대해 소개하고, coin 패키지에 내장된 15개의 간편 함수에 대해 independence test 함수로 변환하는 절차를 설명하고자 한다. 또한, 정의한 independence test 함수를 써서 실제 자료의 점근 분포와 순열 검정, 정확 검정에 기초한 p-값을 서로 비교하고자 한다.

• 대한전기학회논문지:전력기술부문A
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• 제52권7호
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• pp.401-406
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• 2003

Electric power industries in several countries are currently undergoing major changes, mainly represented by the privatizations of the power plants and distribution systems. Reliable operations of the power plants directly contribute to the revenue increases of the generation companies in such competitive environments. Strategic optimizations should be performed between the levels of the reliabilities to be maintained and the various preventive maintenance costs, which require the accurate estimations of the power plant reliabilities. However, accurate estimations of the power plant reliabilities are often limited by the lack of accurate power plant failure data. A power plant is not supposed to be failed that often. And if it fails, its impact upon the power system stability is quite substantial in most cases, setting aside the significant revenue losses and lowered company images. Reliability assessment is also important for Independent System Operators(ISO) or Market Operators to properly assess the level of needed compensations for the installed capacity based on the availability of the generation plants. In this paper, we present a power plant reliability estimation technique that can be applied when the failure data is insufficient. Median rank and Weibull distribution are used to accommodate such insufficiency. The Median rank is utilized to derive the cumulative failure probability for each ordered failure. The Weibull distribution is used because of its flexibility of accommodating several different distribution types based on the shape parameter values. The proposed method is applied to small size failure data and its application potential is demonstrated.

• 전기학회논문지
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• 제67권11호
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• pp.1455-1462
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• 2018

As the interests in eco-friendly energy has increased, the interests in Electric Vehicles(EVs) are increasing as well. Moreover, due to the government's economic support for EVs, penetration level of it has rapidly increased. These sharp increases, however, induce various problems in distribution system, such as voltage/frequency variations, peak demand increasement, demand control, etc. To minimize these possible matters, lots of research have conducted. Nevertheless, most of it assumed extremely important factors, such as numbers and charging patterns of EVs. It inevitably results in errors in their research, and thus make it difficult to prevent the possible matters from EVs. In this paper, therefore, we use actual EVs charging data from KEPCO, and analysis and deduction of it were conducted. The simulations were carried out for four aspect(season, region, purpose).

• 유통과학연구
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• 제12권5호
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• pp.71-80
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• 2014

Purpose - The object of this paper is to ascertain how Japan has become a powerful trader in the international grain market. A case in point is the world's third largest U.S. major grain trader, Gavilon, merged with general trading company Marubeni in 2012. What are Japan's strategies and their implications? Research design, data, and methodology - The study analyzed Japanese Ministry of Agriculture, Forestry, and Fisheries data, and data from daily and weekly papers. The paper employed various data and research methodologies. Results - The Lee Myeong-Bak government tried for three years to create a company similar to Cargill, but the project eventually failed. On the other hand, Japan has emerged as a leader in the international grain distribution market for the past 50 years, with the cooperation of government and private companies. Conclusion - The findings of this study show that Korea, China, India, and other countries' international major grain companies now compete to be powerful, major grain traders. South Korea could be the leader of the international grain market through the development of a more careful and long-term strategy.

• 상하수도학회지
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• 제27권3호
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• pp.351-361
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• 2013

In this study the Principal Component Analysis (PCA) was applied to flow data in a water distribution pipe system to analyze the relevance between the flow observation dates, which have the outliers of observed night flows, and the maintenance records. The data was obtained from four small size water distribution blocks to which 13 maintenance records such as pipe leak and water meter leak belong. The flow data during four months were used for the analysis. The analysis was carried out to identify an appropriate analysis period for a PCA model for a water distribution block. To facilitate the analyses a computational algorithm was developed. MATLAB was utilized to realize the algorithm as a computer program. As a result, an appropriate PCA period for each of the case study small size water distribution blocks was identified.

• 정보보호학회논문지
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• 제13권2호
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• pp.107-114
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• 2003

본 논문에서는 DIAMETER AAA(Authentication, Authorization and Accounting) 하부 구조를 가지고 Mobile IP 액세스 기법을 사용하는 cdma2000 패킷 데이터 서비스에서 W(mobile node)와 AAAH(home AAA server)간의 상호 인증과 Mobile IP 개체들간에 안전한 세션키 분배를 위한 방법을 제안한다. 제안된 프로토콜은 DIAMETER AAA 하부 구조를 가정하며 c의 비효율성을 개선하고, 인증과 키 분배 프로토콜의 안전성 요구 사항들을 모두 만족한다. 또한 1xEV-DO에 대한 패킷 데이터 세션 하이재킹 공격을 방지하기 위해 제안된 기법에 의해 분배된 키를 1xEV-DO 무선 인터페이스 패킷 데이터 보안을 위한 키 생성에 적용한다.

• 유통과학연구
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• 제20권3호
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• pp.23-31
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• 2022

Purpose: The purpose of this study is to analyze the Safety and Logistical Distribution Management system in Thailand's Highway Work Zone based on data from Logistics drivers. Accidents in highway construction zones have caused enormous casualties in Thailand yearly. Statistical data shows evidence of correlation between numbers of accidents and drivers' recklessness. Research design, data, and methodology: In this study, we conducted an in- depth interview with 414 logistics drivers and highway construction workers in Khon Kaen province, Thailand. The data was collected based on 63 questionnaires aiming at capturing factors contributing to the risk of safety and cause of accidents in logistic infrastructures such as Highway work zone. Results: The result reveals two significant factors affecting safety in highway work zone, which includes construction environment and safety management system. Moreover, the result shows that feeling of afraid and confused while driving within the construction zones significantly affecting driver's risk of having an accident. Conclusions: The findings of this study offer that a strategic planning and evaluation of the logistics drivers' satisfaction and construction workers' participation to mitigate highway accidents at construction zones and that drivers' knowledge and perception toward construction safety management plays a significant role in preventing highway accidents at the construction areas.

• 유통과학연구
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• 제22권7호
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• pp.83-94
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• 2024

Purpose: This article aims to investigate the influence of pricing and distribution on the level of satisfaction and purchase decisions among consumers of pharmaceutical products in Kazakhstan. Research design, data, and methodology: A mixed-methods research design was utilized, incorporating primary and secondary data. Primary data were collected through a survey administered to customers across various pharmacy types, with 100 valid responses analyzed. Secondary data involved an extensive review of existing literature and analysis of national statistics concerning the pharmaceutical market trends from 2008 to 2022. Results: The results reveal a complex relationship between price perceptions and customer satisfaction. A significant segment of the population views current drug prices as high, which affects their satisfaction levels and purchase decisions. The study also highlights the importance of service quality in enhancing customer satisfaction, suggesting that service improvements could mitigate some of the negative perceptions of pricing. Conclusions: This research contributes to the limited but growing body of knowledge on the impact of pricing strategies on consumer satisfaction in the pharmaceutical sectors of developing countries like Kazakhstan. Focusing on economic and behavioral aspects, this study provides a more holistic understanding of the factors driving consumer satisfaction and purchase behaviors in this critical sector.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2015년도 제46회 하계학술대회
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• pp.286-287
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• 2015

Currently, Studies on improving the reliability of power supply is becoming an important issue because of the increase in demand of the electric power system. Therefore necessity of automation in distribution system is increasing day by day. However, a measured voltage data from FRTU of distribution automation system is incorrect because of installation space limits. Therefore there is a need of system analysis method by considering the characteristics of the distribution system. For a distribution system, applying the power flow method of transmission system has some problems, as distribution is radial system and it has unbalanced load. Therefore power flow by considering the characteristics of the distribution system have been studied. Existing power flow analysis of the distribution system has different methods like direct analysis method, backward/forward sweep method, modified method of newton raphson etc. In this paper, an improved power flow analysis method based on backward/forward sweep method is proposed in order to efficiently operate the distribution automation system. The proposed method of power flow has been verified through the result of case study.

• 유통과학연구
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• 제18권11호
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• pp.5-13
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• 2020

Purpose: This research investigates the cost behavior of the distribution industry. Specifically, we investigate if the ratio of the increase in costs with an increase in sales is consistent with the ratio of the decrease in costs when sales decrease. Traditionally, cost is assumed to be symmetrical. In the case of the distribution industry, it was expected that the downward rigidity of the cost would be shown because it would be very difficult to decide to adjust resources when sales temporarily decrease. Therefore, studies have looked at Korean capital markets based on manufacturing and steel industries. However, no research has been done on the distribution industry. Research design, data, and methodology: To verify the hypothesis of this study, the asymmetry of cost was measured by Anderson et al. (2003). The sample used 28,695 firm-year data from 2002 to 2019 for the KOSPI and KOSDAQ stock markets. Results: The empirical analysis results are as follows. First, asymmetry of cost was observed in the case of the distribution industry. We confirm cost rigidity when sales decreased. Conclusions. This is the first study to look at cost behavior in the distribution industry, and the downward rigidity of cost in the distribution industry is observed.