• Journal of the Institute of Electronics Engineers of Korea TC
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• v.49 no.7
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• pp.23-31
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• 2012

Resource allocation, such as joint rate control and scheduling, is an important issue in cognitive radio networks. However, it is difficult to jointly consider the rate control and scheduling problem due to the stochastic behavior of channel availability in cognitive radio networks. In this paper, we propose an asymmetric joint rate control and scheduling technique under reliability constraints in cognitive radio networks. The joint rate control and scheduling problem is formulated as a convex optimization problem and substantially decomposed into several sub-problems using a dual decomposition method. An algorithm for secondary users to locally update their rate that maximizes the utility of the overall system is also proposed. The results of simulations revealed that the proposed algorithm converges to a globally optimal solution.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.43 no.3
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• pp.53-60
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• 2020

Evaluating the operational efficiency of electric vehicle charging stations (EVCSs) is important to understand charging network evolution and the charging behavior of electric vehicle users. However, aggregation of efficiency performance metrics poses a significant challenge to practitioners and researchers. In general, the operational efficiency of EVCSs can be measured as a complicated function of various factors with multiple criteria. Such a complex aspect of managing EVCSs becomes one of the challenging issues to measure their operational efficiency. Considering the difficulty in the efficiency measurement, this paper suggests a way to measure the operational efficiency of EVCSs based on data envelopment analysis (DEA). The DEA model is formulated as constant returns of output-oriented model with five types of inputs, four of them are the numbers of floating population and nearby charging stations, distance of nearby charging stations and traffic volume as desirable inputs and the other is the traffic speed in congestion as undesirable one. Meanwhile, the output is given by the charging frequency of EVCSs in a day. Using real-world data obtained from reliable sources, we suggest operational efficiencies of EVCSs in Seoul and discuss implications on the development of electric vehicle charging network. The result of efficiency measurement shows that most of EVCSs in Seoul are inefficient, while some districts (Nowon-gu, Dongdaemun-gu, Dongjak-gu, Songpa-gu, Guro-gu) have relatively more efficient EVCSs than the others.

• Journal of Korea Game Society
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• v.11 no.6
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• pp.115-125
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• 2011

Recently, a sharp increases of users of smartphone is not only cause an rapid growth smartphone-games market, but also secured it's position as a high value market. thus have to begets a multilateral study to the smartphone of newly-rising. however the earlier studies were researched previous smartphone, despite extended research is needed for smartphone-games. therefore the study's purpose is to draw a main factors it has a decisive effect for recommendation and sustainable-usage through recognizing the cause-and-effect relationship with purchase intention, purchase action, satisfaction, recommendation, and sustainable usage that based purchase-effect-factors of smartphone-games. for this study the questionnaire of 293 was taken. and structural equation model was adopted to analyze this study.

• Transactions of the Korean hydrogen and new energy society
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• v.27 no.6
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• pp.712-720
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• 2016

When bioethanol and water are mixed at a proper ratio, phase separation can occur because of the immiscibility of biobutanol with water. Phase separation in bioethanol blends fuels is a major problem for gasoline vehicle users due to effect of octane number and component corrosion. Thus, in this study, the phase separation of bioethanol was examined effect of bioethanol blends (E3 (3 vo.% bioethanol in gasoline), E5 and E10) in presence of water. The effect were evaluated behavior with phase separation test, simulation test of fuel tank in gas station according to water addition volume and it was investigated change of water content, bioethanol content and octane number for gasoline phase in bioethanol blends (E3, E5 and E10) every 1 week after water addition. The E3 occurred phase separation more easily than the E5 and E10 in small water contents because solubility of water on ethanol content difference in gasoline-ethanol. It was kept a initial level of water content, bioethanol content, and octane number by repeated sample replacing in simulation test of fuel tank.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.10a
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• pp.737-740
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• 2013

The widespread use of smart home appliances with smart home networking is leading to a next generation of a new technology that exploit user contextual information to provide a richer experience. However, in the most part of home networking systems the intelligent personalization services between user and home appliances have not been adequately supplied in respect of the long lifespan of the legacy home appliances. In addition, without installing smart home appliances when constructing new building the users can not use this service. To use this service, the legacy home appliance need to attach enabler equipped with the various sensors just as it is smart home appliances. The goal is to create a service that enables appliances to exchange information and control their actions through the IoT gateway to achieve nonintrusive behavior and customized services without human intervention. In this paper, we propose a ontology model to represent the user context to be able to induce right service automatically and use it to discover, utilize and enhance different services in real time that the user may be interested in.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2017.05a
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• pp.730-732
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• 2017

While the short term effect of diet and exercise therapy has been proven, there has still been a problem of its long term effect. So, researchers has utilized behaviour modification therapy. It is expected to lead to natural weight loss by modifying wrong dietary life patterns and practices. However, this approach has turned out to be a more effective method for weight maintenance than loss of weight. In spite of its strength, as a matter of fact, persistent and continuous effort for weight management has not worked properly. This study proposes an artificial intelligence approach with the advantages of behaviour modification therapy, overcoming current approaches which is goal-driven and too uniform. For this, we plan to develop a health management program in which users get the messages that are customized for themselves according to different situations so that it can promotes persistent effort for exercise. Here, customized messages are handled by AI techniques, which eventually promotes soft persuasion, encouragement, and motivation.

• Journal of Digital Contents Society
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• v.14 no.2
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• pp.135-142
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• 2013

In this study, I research about extensions and changes of user experience by using smartphone from the point of conceptual metaphor based on embodied cognition and the remediation characteristics. The result of this study is as follow; The first, container schema and path schema as center image schema of the conceptual metaphor are a proper theories to be mapped user experience by using smartphone because of including embodied schema structure by human physical experience. The second, user experience of smartphone in the point of remediation is remediated by smartphone. And physical space is rededicated and interacted to behavior space by the user experience. The third, the conceptual metaphor of smartphone UX activate container chema through implicit interaction and has transparent immediacy to ingenerate existence of media. The forth, path schema that is activated from explicit interaction makes users to experience hypermediacy. Conceptual metaphor and remediation in this study could be used to theoretical framework and to explain new user experience from using smartphone.

• Fashion & Textile Research Journal
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• v.22 no.4
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• pp.432-445
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• 2020

This study identified the utilization characteristics of individual fashion taste expression on Instagram, and examined the impact of the use of the media on the formation and change of fashion taste. The research method conducted 1:1 indepth interviews with 19 people in their 20s and 30s using 501 images for analysis. The results of this study are as follows. Posting, searching, and reading behavior on Instagram were identified in three dimensions (self-expression, information gathering, and relationship orientation). In the image of self-expression, clothes were displayed at the time so that they could be checked and applied in other ways. Accumulated posts inspired people to look back on past styles and use them to reflect on the present. A media environment that was constantly exposed to information in real time allowed people to try various styles by imitating other users' posts and share in a process of creatively exploring styles to help organize fashion tastes developmentally. Participants had selective relationships with people of similar tastes who experienced the pleasure of enjoying through the exchange of tastes in fashion. These taste mates directly influenced the formation or change of tastes, serving as a criteria for styles or presenting new styles. In this study, fashion taste was formed by individual efforts of pursuit (not a collective social class choice) and was a continuous process of constantly changing that also exploring discriminatory styles.

• Journal of the Korea Society of Computer and Information
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• v.23 no.4
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• pp.131-138
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• 2018

In the recent years, with a purpose to provide visual and psychological stability to patients and hospital users, Affordance design theory based on perceptual psychological thought has been applied as hospital design. In the past, hospital service design was focused on but Affordance design theory focuses on the patients' experience and methodological research on . The characteristics of the application of Affordance design in the case of patients' experience and service point is as follows:- Firstly, Affordance design is applied when the objective of the patient's experience and the functionality of the object are combined. In other words, affordance design is a condition that arises when encounter between service contact point and patients' experience takes place. Secondly, In the field of Hospital service design, Affordance concepts in and its application can be divided on the functions of experience, cognition and sense following the application of Affordance concepts in Hospital service design. Thirdly, Affordance design method sets meaning of the action received through information provided by morphological features. The condition and surrounding has to be designed in a way that it can induce active behavior of the patient. This study has significance as it has been studied from the perspectives of Affordance theory of design psychology in addition to the physical environment of the hospital, the point of interaction between the hospital and patient, along with the elements of experience design. This study proposes the necessity of analytical study in the field of service design implementation considering various stakeholders in the service contact points of small and medium hospitals in Korea. Furthermore, study of the application of Affordance design can be complemented by reflecting the size of hospitals, the characteristics of specialties, and the specific service environment of each hospital can also be conducted.

• Journal of Digital Convergence
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• v.15 no.2
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• pp.527-535
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• 2017

As interest increases in health promotion through sports, demand for public sports facilities is steadily growing. However, there is a lack of research on operation and management compared with the supply plan of public sports facility. In this context, the aim of this study is to address problems of management of public sports centers and suggest strategies for vitalizing the facilities through the big-data. The data are collected from web such as news, blog, and cafe for one year in 2015. From the big-data, We can find that the national sports centers and the open gyms showed similar users' behavior but showed different needs. Both facilities have been used as sports and leisure area and have a high percentage of visitors for other purposes such as walking, picnics, etc. However, while the national sports facilities which were used for more specialized programs, the open sports center were used as leisure space.