• Journal of the Korean Society of Safety
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• v.32 no.6
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• pp.1-8
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• 2017

P-PIE is a program developed to estimate failure probability of pipes and pressure vessels considering fatigue and stress corrosion crack growth. Using the program, crack growth simulation was performed with an initially existing crack in order to examine the effects of initial crack depth distribution on the leak probability of pipes. In the simulation stress corrosion crack growth was considered and several crack depth distribution models were used. From the results it was found that the initial crack depth distribution gives great effect on the leak probability of pipes. The log-normal distribution proposed by Khaleel and Simonen gives lower leak probability compared other exponential distribution models. The effects of the number and the quality of pre-service and in-service inspections on the leak probability were also examined and it was recognized that the number and the quality of pre-service and in-service inspections are also give great effect on the leak probability. In order to reduce the leak probability of pipes in plants it is very important to improve the quality of inspections. When in-service inspection is performed every 10 years and the quality of inspection is above the very good level, the leak probability shows nearly constant value after the first inspection for an initially existing crack.

• The Korean Journal of Applied Statistics
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• v.28 no.6
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• pp.1245-1255
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• 2015

In this paper, we investigated the major 8 companies of Korean stock market, and carried out the goodness of fit and independence tests. We found out the distributions of absolute returns are closed to compressed exponential distribution. The parameters are dominant that 1 < ${\beta}$ < 2, followed by ${\beta}=1$(exponential distribution) and ${\beta}=2$(normal distribution). Meanwhile, we assured that most of the absolute returns for major 8 companies have relevance to each other by chi-square independence test.

• Journal of Electrical Engineering and Technology
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• v.11 no.1
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• pp.167-174
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• 2016

The Korean distribution line currently consists of overhead ground wires (OHGW), overhead distribution lines, neutral wires (NW), and messenger wires (MW). The MW is installed under the NW. The lightning protection system in Korea is focused on OHGW and lightning arrester and the MW are not considered. Therefore, this paper proposes the applicability of MW for purpose of lightning protection. For this, we analyzed the effects of lightning overvoltage according to the existence of OHGW and MW and the grounding conditions of the MW in the Korean distribution system. The grounding conditions of the MW that we took into consideration were the common or separate grounding of the MW and NW. The analysis based on the equivalent circuit of the distribution pole at each condition was performed. The distribution lines and lightning were modeled using the Electromagnetic Transients Program (EMTP). For each of the installation conditions of the OHGW and MW, the various lightning conditions were simulated and analyzed for both direct and indirect lightning. The simulation results showed that, if the OHGW was not installed in the Korean distribution system, the lightning overvoltage could be reduced by the common grounding of the MW and NW.

• Journal of the Korean School Mathematics Society
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• v.9 no.3
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• pp.309-316
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• 2006

This study examined the ambiguous using the terminology of statistics at mathematics textbook of highschool in Korea and proposed the correct using of sampling error and sampling distribution of sample mean with consistency. And this paper proposed that the concept of error have to teach in context of sampling action in school mathematics.

• Journal of Distribution Science
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• v.16 no.4
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• pp.17-20
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• 2018

Purpose - The purpose of this paper is to analyze and illustrate Amazon's business strategies and its success in terms of its distribution strategy and business practices. Research design, data, and methodology - This is an analytical case study that examines Amazon's business strategies to demonstrate the importance of technologies to the success and sustainability of its organization. Results - The analysis indicates that the business strategies, including technology, distribution infrastructure, and customer service, are the most vital factor for the success and rise of Amazon, and these strategies have separated Amazon from its competitors in both e-tail and brick and mortar retail industries. Conclusions - Given Amazon's continued growth that came with its constant strive for delivery and cost efficiency, technology innovation, and customer satisfaction, it was inevitable that Amazon would eventually venture into different types of businesses. The previous and current Amazon's business strategies demonstrate that Amazon will continue to focus on developing and implementing new and creative strategies to separate itself from the rest of the retail and e-businesses. Furthermore, retail businesses in the most high-tech countries in the world, including Japan, Korea, and Russia, may have to adopt business strategies that are similar to those of Amazon to maintain their competitiveness.

• ALGAE
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• v.22 no.1
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• pp.45-52
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• 2007

An intertidal marine benthic algal vegetation and vertical distribution at Kangnung and it’s vicinity, the eastern coast of Korea was investigated to clarify the community structure and vertical distribution by quadrat method. Marine algae identified from the area were 116 species; 15 green, 31 brown and 70 red algae. The dominant species were Ulva pertusa, Codium fragile, Undaria pinnatifida, Dictyota dichotoma, Gelidium amansii, Corallina pilulifera, Carpopeltis affinis, Grateloupia filicina, Pachymeniopsis elliptica and Chondrus ocellatus at study sites. The vertical distribution of intertidal marine algae was divided into three distinct zones. They were characterized by Porphyra tenera at the upper, Enteromorpha spp. and Ulva pertusa at the middle, and Sargassum thunbergii, Hizikia fusiformis and Pachymeniopsis elliptica at the lower zones, respectively. The vertical distribution of subtidal zone algae were characterized by Laminaria spp. at 15m depth and Kjellmaniella crassifolia at 15 to 25 m depths, whereas Agarum cribrosum was dominant at the lower zone than 25 m depth.

• Journal of the Korean Solar Energy Society
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• v.24 no.4
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• pp.11-18
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• 2004

A solar concentrator, named KIERDISH II, was built at KIER in order to investigate the feasibility of high temperature solar energy application system. The constructed concentrator is a dish type solar concentrator with a focal length of 4.68m and a diameter of 7.9m. To successfully operate KIERDISH II, optimal design of the absorber is very important and flux density distribution has to be known. The focal flux density distribution on the receiver was measured. We have observed the shape and size of flux images and evaluated percent power within radius. Flux density distribution is usually measured by a CCD(charge coupled device) camera and a radiometer. In this paper we present a flux mapping method to estimate the characteristic features of the flux density distribution in the focal region of solar concentrator. The minimum radius of receiver is found to be 0.15m and approximately 90% of the incident radiation is intercepted by receiver aperture.

• Journal of Distribution Science
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• v.12 no.5
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• pp.109-117
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• 2014

Purpose - The study investigates the history, production methods, market scale, and distribution of the traditional liquors of three countries: South Korean sokokju, Chinese shaoxing-chiew, and Japanese sake. These have similar production methods, being made from rice or cereal, cores of their respective food industries. Research design, data, and methodology - The study investigated the history of the three liquors, liquor classification in the three countries, and production methods. It examined the scale of the traditional liquor market and these countries' distribution structure. Results - Brand cognition of traditional liquors is affected by a focus on wellbeing and LOHAS (lifestyle of health and sustainability). Promotion and marketing strategies along with a high quality image, shelf life of draft liquor, traditional liquor identification systems, and high taxes on traditional liquor, and the need for continuous R&D and training of professionals all impacted the industry. Conclusions - These countries play important roles in world trade, seeking economic integration. By forming a free trade agreement (FTA), their traditional liquors, with a proud history, can be jointly branded in the world market.

• Journal of Distribution Science
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• v.16 no.7
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• pp.47-56
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• 2018

Purpose - This study aims to not only investigate spatial pattern of immigrants' residence and crime occurrences in South Korea, but shed light on how geographic distribution of immigrants and immigrant segregation affect crime rates. Research design, data, and methodology - Th unit of analysis is Si-Gun-Gu municipal level entities of South Korea. The crime data was obtained by Korea National Police Agency and two major types(violence and property) of crime were measured. Most demographic, social, and economic variables were derived from Korean Census Data in 2015. In order to examine spatial patterns of immigrants' distribution and crime rates in South Korea, the present study utilized GIS mapping technique and Exploratory Spatial Data Analysis(ESDA) tools. The causal linkage was investigated by a series of regression models using STATA. Results - Spatial inequality between urban metropolitan vs rural areas was visualized by mapping. Assuming large Moran's I value, spatial autocorrelation appeared to be quite strong. Several neighborhood characteristics such as residential stability and economic prosperity were found to be important factors leading to crime rate change. Residential distribution and segregation for immigrants were negatively significant in the regression models. Conclusions - Unlike the traditional arguments of social disorganization theory, immigrant segregation appeared to reduce violent crime rate and the high proportion of immigrants also turned out to be a crime prevention factor.

• Journal of Distribution Science
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• v.17 no.3
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• pp.21-30
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• 2019

Purpose - While many related prior studies have focused on the segregation by race and ethnicity, the academic interest in the separation of residence by income and social class is gradually increasing. This study aims to not only investigate spatial pattern of economic segregation and poverty rate in South Korea, but also shed light on what affect residential distribution of the poor. Research design, data, and methodology - The unit of analysis is Si-Gun-Gu municipal level entities of South Korea. Most demographic, socioeconomic, and residential variables were derived from Korean Census Data in 2015. In order to examine spatial patterns of economic segregation and poverty rate in South Korea, a series of measurements and visualization was conducted through the Geo-Segregation Analyzer and ArcGIS programs. Determinants of economic segregation and local poverty rates were investigated by regression analyses using STATA. Results - The spatial patterns of areas with high poverty rates were extremely clustered, while the distribution of areas with high economic segregation was relatively evenly distributed. Demographic, residential, and local factors appeared to affect whether the poor live in particular area or spread evenly. Conclusions - The factors that raise the poverty rate result in lower level of economic segregation, while factors that reduce the poverty rate lead to severe level of economic segregation.