• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.3
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• pp.624-629
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• 2018

The current study was conducted to develop a portable composite gas detector allowing the detection of both $CO_2$ and $CH_4$ gases by means of the Non Dispersive Infra-Red (NDIR) method. The gas detector is configured to radiate infrared waves using infrared lamps, where the wavelength of the infrared light is reduced due to absorption throughout the chamber, and this reduction (absorption) is detected by the absorption detector, before being converted and amplified to a 3.5V~6V electrical signal, providing as accurate a measurement as possible. The conventional singe sensor method measures the relative measurement by absorbing only specified wavelengths of infrared radiation, which in the case of gas detection leads to problems with accuracy due to the lack of a reference sensor when detecting light with a wavelength of only $4.26{\mu}m$. The dual sensor employed in this study provides a comparative measurement between the reference value derived from the wavelength of $3.91{\mu}m$, which is not influenced by other gas sources, and the measurement value derived from the wavelength of $4.26{\mu}m$, in order to reduce the errors and enhance the reliability, thereby allowing low power consumption for portable devices and multi-gas detection for both $CO_2$ and $CH_4$ gases. The portable composite gas detector developed herein provides a measurement rage of 0ppm~5,000ppm for $CO_2$ gas, and 0.5%vol for $CH_4$, which allows the determination of whether the $CO_2$ and $CH_4$ contents in indoor air are less than 1,000ppm or not. The current study established that the composite gas detector can be interlinked with firefighting appliances through portable devices or home automation, and is anticipated to be very effective in fire prevention.

• The Korean Journal of Applied Statistics
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• v.22 no.5
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• pp.1115-1129
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• 2009

Previous research has recently shown that non-cognitive factors such as attitudes toward statistics contribute positively to statistics learning, Hence, helping students develop positive attitudes toward statistics has become one of the essential goals of statistics teaching. A wide variety of instruments assessing attitudes toward statistics were developed and validated in foreign countries, but not many in Korea. The SATS-36(Survey of Attitudes Toward Statistics-36; Schau et al., 1995) has been regarded as one of the most valid measures of attitudes toward statistics. Therefore, this study was designed to validate a Korean version of Survey of Attitudes Toward Statistics(K-SATS). Instead of six factors of the original scale, a five-factor structure including interests, value, cognitive competence, difficulty, and effort was empirically supported by the Korean student sample. The results evidenced high reliability and construct validity of K-SATS. In addition, students' attitudes towards statistics differed across gender, level of statistics courses, degree programs, and major. These findings were discussed in terms of their implications for future research and statistics teaching.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.36 no.4
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• pp.637-644
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• 2016

This study sought to reevaluate the water supply capacities of the Nakdong river dams, and identify measures to remedy any shortages using weirs, focusing on 5 multipurpose dams and 8 weirs. The reevaluation of the dams was performed by the HEC-5 program using the original design criteria and inflow data recorded for each dam. The results show that the capacities of the 3 dams has decreased to 73~87%. Three simulations were performed to determine the effect of coordinating the dams and weirs. The first simulation was based on individual operation of the dams; the second on coordinated operation of the dams; and the third on coordinated operation of the dams and weirs. To obtain a water supply reliability of 95%, the annual water shortage was calculated for a 20-year period (1992~2011). In addition, long-term runoff simulation data used in the national river basin investigation by the Ministry of Land, Infrastructure and Transportation were used with the dam discharge data, because long-term inflow data for the weirs were not available. The simulations were performed by the HEC-ResSim program, with the reservoir network divided into 2 groups based on the Waegwan water station. The results show that water supply capacity for the 3 simulations to be $2424Mm^3/yr$, $2612Mm^3/yr$ and $2734Mm^3/yr$, respectively. This indicates that coordinated operation of the dams and weirs could provide an additional water supply of $122Mm^3/yr$.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.16 no.2
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• pp.81-89
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• 2002

The Battery Energy Storage System (BESS) has lots of advantages such as load leveling, quick response emergency power (spinning reserve), frequency and voltage control, improvement of reliability, and deferred generation and transmission construction. However, it is very critical that economic feasibility requires justification from the customer side of meter to promoting the dissemination of BESS in nation widely. In this paper, we proposed the economic assessment model of customer owned BESS which is complemented and improved the existing model. The proposed model is applied to the typical customer types, i.e. light industrial, commercial, and residential, which are taken from the statistical analysis on the load profile survey of Korea Electric Power COmpany (KEPCO). The economic viability performed for each customer load type to justifying their economic feasibility of BESS installation from the economic measures such as payback period, Net Present Worth (NPW), Rate Of Return (ROR). The results show that the BESS has economic benefits to the specific customer type, i.e. residential customer. Therefore, the government and the energy agency should be committing the support program, such as tax incentive, financial support, to disseminate the BESS nation widely. The results of this paper are useful to the customer investment decision-making and the national energy policy & strategy in Korea.

• Journal of Distribution Science
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• v.14 no.5
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• pp.97-106
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• 2016

Purpose - Social commerce is a certain way of how people buy some products together with others through the internet sites with mutual interactions among customers with the benefits of SNS when buying some products. At present, China market has some problems due to its rapid growing. However, empirical research or academic approach to social commerce has not been made enough. So, it is important for Chinese social market to develop and enlarge the customers with stability under the reliability and satisfaction. Also it is important for them to have repurchase intention. Nowadays, it is necessary to find the factors on customer satisfaction and trust, whereas consumers' dissatisfaction and unreliability are increasing on social commerce recently. In addition, researches on social commerce have been actively pursued by a variety of domestic and foreign scholars. However, researches on social commerce and Chinese market are short of, and they have some limitations because of the rapid growth of the market even though it is the early stage. The current situation requires researches on consumers' repurchase intention for continuing growth in the future according to the growth of Chinese social commerce. Research design, data, and methodology - The literature and the empirical studies are combined in order to achieve the purpose of the study. Deriving social commerce features and consumer properties as factors affecting the repurchase intention through the literature, and these factors have modeled a series of assumptions about the impact on satisfaction and trust, and have established hypotheses to verify them. The survey which is conducted to test the hypothesis and questionnaires are derived based on the variables discussed in the previous study. Appropriate measures were developed and tested on 227 respondents in China with a cross-sectional questionnaire survey. The path relationships of the research model were analyzed by SPSS 23.0 and Amos 23.0. Results - Research results about social commerce characteristics and factors affecting the repurchase intention are presented to Chinese market companies that adopt business models and consumer characteristics. In addition, this study focuses on the characteristics of social commerce, from two-dimensional characteristics of the consumer satisfaction, trust and the impact on the repurchase. Therefore, social commerce features and consumer properties based on the results of this study may lead the strategic implications that may increase the repurchase intention. Conclusions - The classification reviewing the previous findings related to social commerce and social commerce features affects social commerce repurchase (price discount, interactivity) and consumer characteristics (impulsivity, innovation, collectivism). It affects repurchase on factors and analyzes empirically. The empirical results identify major characteristics (social commerce characteristics, attributes) that affect the repurchase intention, and give the practical implications as well as the business strategies that are able to enhance social commerce repurchase consumers. Social commerce is a certain way of how people buy some products together with others through the internet sites with mutual interactions among customers with the benefits of SNS when buying some products.

• Journal of Distribution Science
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• v.17 no.2
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• pp.77-89
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• 2019

Purpose - This study presents the relationships between parent brand-self image congruence, parent brand -functional congruity, perceived fit between parent brand and extension product, and consumer's attitude toward extension product using the structural equation model. As for preceding concepts having a direct effect on consumer's attitude toward brand extension, the study focuses on parent brand-self image congruence and parent brand-functional congruity. It also looks at the effect of parent brand-self image congruence and parent brand-functional congruity on the consumer's attitude toward extension product and identifies if the perceived fit between parent brand and extension product is a concept playing a mediating role between parent brand-self image congruence or parent brand-functional congruity and consumer's attitude toward brand extension product. Research design, data, and Methodology - SPSS for Windows 18.0 and AMOS 18.0 were used for data analysis. Then, the Cronbach's α coefficient was obtained using SPSS for Windows 18.0 to measure reliability. In addition, the convergence and discriminative measures of the measured items were statistically verified using AMOS 18.0. Finally, we have validated a path model and a parameter model in which brand personality-self-matched attitude toward brand extension. Results - Studies have shown that the impact of parent brand-self image consistency and parent brand-functional consistency on the attitude of extended products was positive. Perceived fit between parent brand and extension products has been shown to play a role of intermediary between parent brand-self image congruence and consumer attitudes to extended products. However, perceived fit between parent brand and extension products did not play a role as intermediary between the parent brand-functional congruity and the attitude toward the extended product. Finally, in relation to the causal relationship between parent brand-congruity (self image/functionality) and attitudes to extended products. The effect of parent brand-functional coherency on attitudes toward extended products was found to be greater in groups with higher involvement than in those with lower involvement. Conclusions - Although few studies have been done on what variables mediated when parent brand-self image consistency and parent brand-functional coherency affect consumer attitude, this paper is significant in finding whether perceived fitness between the parent brand-congruity and the extension product is mediated.

• The Journal of the Korea Contents Association
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• v.20 no.10
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• pp.654-678
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• 2020

Job crafting has gained prominence in organizational practice as an important factor to cultivate positive performance, the purpose of this study is to present theoretical and practical implications of job crafting by examination of the effective variables that induce job crafting. We verify the correlation between shared leadership and job crafting and the mediating effect of learning goal orientation and knowledge sharing in the relationship between these two variables. Hypotheses were established on the basis of precedent research and various theories including social cognitive theory and affective events theory. The data were collected by conducting online surveys of 318 office workers who have served in various domestic organizations. The reliability and validity of the collected data were verified by SPSS 25.0 and AMOS 25.0, and the hypotheses were analyzed by SPSS process macro 3.0. The study found that shared leadership yields positive effects on the learning goal orientation, knowledge sharing and job crafting of participants respectively and that learning goal orientation and knowledge sharing have a mediating effect in the relationship between shared leadership and job crafting. The results of this study present the effectiveness of shared leadership to facilitate the job crafting and implications and future research measures for the organization to develop a system for activating shared leadership, and for strengthening learning goals orientation and knowledge sharing.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.5
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• pp.681-688
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• 2018

As environmental regulations have been strengthened and high fuel efficiency has been in demand in recent years, the number of ships using natural gas as a fuel is increasing. The demand for ships using LPG or methanol, which are emerging as eco-friendly vessel fuels, is also increasing. In this perspective, ME-LGI engines using LPG or methanol as a fuel have attracted considerable attention. Ships equipped with an ME-LGI engine are required to check the reliability of the fuel injection valve during shipping. This means that the development of a fuel injection valve tester is essential for the commercialization of ME-LGI engine. This study conducted the conceptual design of a fuel injection valve tester for ME-LGI engines using a system engineering process in the order of requirements analysis, functional analysis, and design synthesis. In the requirement analysis stage, the operating process of fuel injection valve was analyzed, and the necessity of checking the sealing oil leakage was then derived. In the functional analysis stage, the functions and flow of them were defined at each functional level. In the design synthesis stage, the equipment for each function was set and the process block diagram based on it was derived. In addition, preliminary risk analysis was performed as a part of system analysis and control, and safety measures were added to the conceptual design. This study is expected to be a good reference material for the concept design of other systems in the future because it shows the application process of a system engineering process to the conceptual design in detail.

• Korean Security Journal
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• no.22
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• pp.65-90
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• 2010

Recently, alarmed by the frequent international terrorism or safety accidents, the host countries of world sports events are focusing on security activities for the sake of the participants, facilities, events and competitions. They are alarmed because in case any happenings like international terrorism or safety accident, the contest itself can be criticized to be a failure as much as the international reliability of the host nation may well crash. We can see that any failure in coping with terrorism or safety matters can lead to a nation-wise crisis in the case of Indonesia where the October 12th of 2002 terrorist bomb attack in Bali damaged the image of the nation followed by the similar case in Philippine (Oct. 20th, 2002) where the same terrorist attack dramatically scared away the tourists to the nation. Korea is scheduled to hold the World Championship in Athletics in Daegu Metropolitan City in 2011. Also, it is slated to host various world sports events such as Yeosu International Exposition and Incheon Asian Games. In these contexts, this study analyzes counter-terrorism cases related with the recent international sports events that have been organized in a variety of manners in the era of globalization. This study aims to show alternatives for the safety management in these events. In other words, it is focusing on giving directions to the safety policies of the nation -which may become the future hub of north-east Asia and the world - for more perfect guard and defense, and counter-terrorism activities in all the conferences, sports events and international festivals where any private defense and guard companies are allowed to cooperate with the police force or public security agencies.

• Geophysics and Geophysical Exploration
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• v.23 no.3
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• pp.131-140
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• 2020

In training a classification model using machine learning, the acquisition of training data is a very important stage, because the amount and quality of the training data greatly influence the model performance. However, when the cost of obtaining data is so high that it is difficult to build ideal training data, the number of samples for each class may be acquired very differently, and a serious data-imbalance problem can occur. If such a problem occurs in the training data, all classes are not trained equally, and classes containing relatively few data will have significantly lower recall values. Additionally, the reliability of evaluation indices such as accuracy and precision will be reduced. Therefore, this study sought to overcome the problem of data imbalance in two stages. First, we introduced weighted accuracy and weighted precision as new evaluation indices that can take into account a data-imbalance ratio by modifying conventional measures of accuracy and precision. Next, oversampling was performed to balance weighted precision and recall among classes. We verified the algorithm by applying it to the problem of facies classification. As a result, the imbalance between majority and minority classes was greatly mitigated, and the boundaries between classes could be more clearly identified.