• Journal of The Korean Astronomical Society
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• v.50 no.6
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• pp.167-178
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• 2017

We present a study of the inexplicit connection between radio jet activity and ${\gamma}$-ray emission of BL Lacertae (BL Lac; 2200+420). We analyze the long-term millimeter activity of BL Lac via interferometric observations with the Korean VLBI Network (KVN) obtained at 22, 43, 86, and 129 GHz simultaneously over three years (from January 2013 to March 2016); during this time, two ${\gamma}$-ray outbursts (in November 2013 and March 2015) can be seen in ${\gamma}$-ray light curves obtained from Fermi observations. The KVN radio core is optically thick at least up to 86 GHz; there is indication that it might be optically thin at higher frequencies. To first order, the radio light curves decay exponentially over the time span covered by our observations, with decay timescales of $411{\pm}85$ days, $352{\pm}79$ days, $310{\pm}57$ days, and $283{\pm}55$ days at 22, 43, 86, and 129 GHz, respectively. Assuming synchrotron cooling, a cooling time of around one year is consistent with magnetic field strengths $B{\sim}2{\mu}T$ and electron Lorentz factors ${\gamma}$ ~ 10 000. Taking into account that our formal measurement errors include intrinsic variability and thus over-estimate the statistical uncertainties, we find that the decay timescale ${\tau}$ scales with frequency ${\nu}$ like ${\tau}{\propto}{\nu}^{-0.2}$. This relation is much shallower than the one expected from opacity effects (core shift), but in agreement with the (sub-)mm radio core being a standing recollimation shock. We do not find convincing radio flux counterparts to the ${\gamma}$-ray outbursts. The spectral evolution is consistent with the 'generalized shock model' of Valtaoja et al. (1992). A temporary increase in the core opacity and the emergence of a knot around the time of the second ${\gamma}$-ray event indicate that this ${\gamma}$-ray outburst might be an 'orphan' flare powered by the 'ring of fire' mechanism.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.1
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• pp.101-107
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• 2012

When wireless devises for MICS(Medical Implant Communication Service) or ISM(Industrial Scientific and Medical) bands are designed, it is necessary to verify the performance by using a human body flat phantom. However, most of studies on the phantom are limited to the biological effects of mobile-phone EMF. In this paper, semi-solid phantoms having the electric properties suggested by FCC at MICS and ISM bands are fabricated. The manufactured phantoms satisfy the electric properties($\varepsilon_r=56.7$ and $\sigma=0.94$ at MICS band, $\varepsilon_r=52.7$ and $\sigma=1.95$ at ISM band) at each band. All the composing materials for phantoms are commercially available in domestic market. Two methods using both polyethylene powder and TX-151 and glycerin at each band are proposed for diverse purpose. The electrical properties of the fabricated phantoms are measured by a dielectric probe kit and network analyzer after the lapse of one day (24 hours).

• Journal of Distribution Science
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• v.14 no.12
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• pp.107-118
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• 2016

Purpose - In today's markets, new technologies such as social network systems and user generated contents have provided consumers with access to unlimited amounts of information and an ability to communicate with other consumers in the world. Specially, the massive of the internet and the development of online communities and interactive platforms offer the potential to cocreate with a large number of consumers. Significant changes in marketplace suggest that simply being consumer oriented is not enough, so firms must learn from and collaborate with consumers to create values that meet their individual and dynamic needs. In these sense, emergent perspectives in marketing highlight new opportunities for co-opting consumers as a means to define and cocreate value through their engagement. Although the importance of consumer co-creation with firms, the current literature lacks the respond to two questions: (1) who are the most competent consumers for creating the values with firm? and (2) what are the stimulaters to help the consumers engage for co-creation? To this answer the question, this research investigate how to structure consumer motivations to encourage consumers to be more engaged for co-creation and what drives a consumer to get involved to respond to a call for co-creation. Research design, data, and methodology - To empirically test the hypotheses, a survey was conducted among consumers who had experienced the co-creation including upstream, downstream, autonomous, and sponsored co-creation with the firms. We collected a total of 343 responses. After we excluded 37 questionnaire because of incomplete responses, a total of 306 questionnaire remained. Working with a sample of 306 responses in Seoul and Kwangju, hierarchical moderated regression is employed to test research hypotheses. Results - The results indicated that consumer creativity and emergent nature are positively related to engagement in co-creation including upstream, downstream, autonomous, and sponsored co-creation. Also, the relationships between consumer creativity/emergent nature and engagement in co-creation were moderated by intrinsic motivation in case of upstream and downstream co-creation. Finally, interaction effects between consumer creativity/emergent nature and extrinsic motivation were not significant. Conclusions - These results suggest that marketing managers have to consider the consumer personality such as creativity and emergent nature and stimulate the intrinsic motivation of consumer to achieve the co-creation project successfully.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.6
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• pp.209-218
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• 2018

The purpose of this study was to explore the relationship between the subjective consciousness and life satisfaction of the elderly, and to see how depression affects this relationship. This includes a new way of thinking about the causes of the elderly's life satisfaction, not only for individual factors, but also for subjective class consciousness. For this aim, we examine the degree of subjective class consciousness, life satisfaction and depression of the elderly, and verify mediation effects of depression between subjective class consciousness and life satisfaction. This study utilized data obtained from the 5th version of the Korea Longitudinal Study on Aging 2014, and considered data from 4,222 elderly aged 65 and over. As a means of study, a structural equation model analysis was conducted. The results were as follows: First, it was confirmed that the subjective class consciousness of the elderly may influence life satisfaction. It was also confirmed that the subjective class consciousness of the elderly also affected depression and life satisfaction among the elderly. When subjective class consciousness was high, depression was low and life satisfaction was high. When depression was low, life satisfaction was high. Second, depression had the mediation effect in which subjective class consciousness affects life satisfaction. Based on these results, this author suggests practical and political issues concerning social welfare to prevent and reduce depression and increase life satisfaction through improving the subjective class consciousness of the elderly. First, policy measures should enhance social capital through housing support policies and leisure use support to enhance the subjective class consciousness of the elderly. Second, the provision of services for the elderly through the establishment of a community-based network to reduce depression should be promoted.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.10
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• pp.517-529
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• 2020

Various facilities in the river working in a complex interdependence network result in both desired and adverse effects. Among these, the weir crossing the river continuously acts in various ways, such as securing river maintenance flow and water level during dry-period, and rising flood level during rainy period. Until now, weir planning was only limited to flood mitigation management. Recently, the demand for securing river environment functions is increasing. Therefore, the necessity for an environmental flow has emerged. Nevertheless, there is no analysis and evaluation of the ecological functional aspects applying the environmental flow when planning facilities. Therefore, this study aimed to develop and systematize an assessment method that considers not only flood control but also river environment. Environmental flow was applied to the weir named Dondaet-bo and hydraulic analysis was conducted for each retention, demolition, and re-installation case. Also, this research was conducted to minimize the impact on the surrounding river facilities and flood assessments from previous perspectives were performed. The study result demonstrated a plan to reinstall the weir as a natural riffle. Through this study, it is expected that the flood control and environmental functions of rivers can be secured in combination.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.13 no.4
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• pp.49-58
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• 2018

In recent years, various studies have been carried out on various types of entrepreneurship and comparative activities according to policy efforts and support such as the activation of a bachelor's degree in the establishment of a university, and attention has been paid to the fact that the participation and the educational effect of the students may be different depending on the type. The purpose of this study is to investigate entrepreneurial motivation, entrepreneurship, and entrepreneurial intention in the case of experiential entrepreneurship class focusing on the theoretical-oriented general entrepreneurship class, And the effect of entrepreneurship on entrepreneurial intention. The data were collected and empirical analysis was conducted to compare the difference between the two groups. The results of this study are as follows: First, out of the motivation factors of entrepreneurs, entrepreneurship education, achievement desire, human network, self - esteem, etc. We can confirm that the motivation of entrepreneurs is recognized more greatly. Second, the entrepreneurship factor was not significantly different from the perception between experiential entrepreneurship lecture and theoretical entrepreneurship learner. Third, experiential entrepreneurship learner perceived more willingness to start business than theoretical entrepreneurship learner. Finally, among the entrepreneurship motivation factors, among the entrepreneurship education, achievement desire and entrepreneurship factor, the risk sensitivity affects the entrepreneurial will. This study suggests that the direction of entrepreneurial education focused on quantitative expansion and the creation of qualitative effects of entrepreneurship education are needed. In the future, it will provide policy implications for revitalizing experiential entrepreneurship education In addition, it can contribute to the diffusion of research on the effect of entrepreneurship education.

• Journal of Korea Water Resources Association
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• v.42 no.7
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• pp.525-535
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• 2009

In this paper a heuristic method for identifying individual pipes in water pipe networks to determine specific sections of the pipes that need to be replaced due to deterioration. An appropriate minimum pipe length is determined by selecting the pipe length that has the greatest variance of the average cumulative break number slopes among the various pipe lengths used. As a result, the minimum pipe length for the case study water network is determined as 4 m and a total of 39 individual pipe IDs are obtained. The economically optimal replacement times of the individual pipe IDs are estimated by using the threshold break rate of an individual pipe ID and the pipe break trends models for which the General Pipe Break Prediction Model(Park and Loganathan, 2002) that can incorporate the linear, exponential, and in-between of the linear and exponetial failure trends and the ROCOFs based on the modified time scale(Park et al., 2007) are used. The maximum log-likelihoods of the log-linear ROCOF and Weibull ROCOF estimated for the break data of a pipe are compared and the ROCOF that has a greater likelihood is selected for the pipe of interest. The effects of the social costs of a pipe break on the optimal replacement time are also discussed.

• The KIPS Transactions:PartD
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• v.18D no.6
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• pp.481-492
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• 2011

Recently, various mobile services are provided by the spread of wireless network infrastructures and smart devices. The improvement of cloud computing technologies increases the interests for enterprise mobile cloud services in various IT companies as well. By increasing the interests for enterprise mobile cloud services, it is necessary to evaluate the use of enterprise mobile cloud services. Therefore, the factors which affect the user acceptance of enterprise mobile cloud services are analyzed on the basis of Davis' technology acceptance model in this research. As analysis results, four external variables have significant effects on perceived ease of use of mobile cloud services. Also, these variables indirectly affect attitude toward using cloud services. The results show that the security is the most important factor for attitude toward using enterprise mobile cloud services. The service users also consider the interoperability as an important factor for the user acceptance of cloud services. The perceived ease of use has more contribution than the perceive usefulness on attitude toward using enterprise mobile cloud services. This research has both industrial and academic contributions because it provides the guideline to companies for introducing the enterprise mobile cloud services and apply the technology acceptance model on new IT services.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.12
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• pp.636-644
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• 2019

The purpose of this study is to explore practical intervention strategies by identifying the relationships among digital informatization capacity, level of digital informatization accessability and life satisfaction of disabled people and to determine differences among these relationships depending on perceived level of social support networks. The participants were 1,639 disabled people from the 2017 digital information gap survey and the results, based on structural equation modeling and multi-group analysis, are as follows. First, digital informatization capacity has a positive influence on the level of digital informatization accessability(β=.65), and life satisfaction(β=.08). The level of digital informatization accessability also has positive influence on life satisfaction(β=.44). Second, the analysis result of the mediated effects of digital informatization accessability level between digital informatization capacity and life satisfaction was significant at a level (β=.29) even greater than the direct effect of digital informatization capacity on life satisfaction. Third, digital information capacity and digital informatization accessability have an influence on life satisfaction regardless of their perceived level of social support. The findings suggest that creating online environments where disabled people can enjoy leisure, culture, and social interaction with high accessibility and utility are as important as providing education for improving their digital informatization capacity.

• Journal of the Korean Society for Library and Information Science
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• v.48 no.4
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• pp.267-295
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• 2014

The purpose of this study is to analyze empirically relationships between learners' psychological factors, knowledge sourcing behavior and knowledge utilization outcomes and to analyze the mediation effect of social learning and relationships among learners. Another purpose is to understand learners' attitude on social learning and knowledge sourcing behavior. The main results of this study are as follows: First, regression results on relationships among learners' psychological factors, knowledge sourcing behavior, knowledge utilization outcomes show that learners' self-efficacy has a positive effect on social learning activity participation, and goal orientation has a positive influence on group knowledge sourcing and social learning activity participation. Users' experiences of social media has a positive effect on group knowledge sourcing, social learning activity participation and social learning interaction. From a knowledge utilization perspective, published knowledge sourcing positively affects knowledge reuse, knowledge application and knowledge innovation. Dyadic knowledge sourcing has positive influence on knowledge reuse. Group knowledge sourcing affects positively knowledge application and knowledge innovation. Second, social learning activity participation factor has full mediation effect on relationship between learners' goal orientation and group knowledge sourcing, and the relationship between users' experiences of social media and group knowledge sourcing. A relationship among members factor has full mediation effect on the relationship between published knowledge sourcing and knowledge reuse, and relationship between published knowledge sourcing and knowledge innovation. Third, the results of in-depth interview show that learners trust and easily collect knowledge from social network services in general. Also, they get a variety of idea for solving information problem from interaction among members in social learning community.