• 전력전자학회:학술대회논문집
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• 전력전자학회 2010년도 하계학술대회 논문집
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• pp.129-130
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• 2010

For the high power demand and N+1 redundancy, this paper presents the digital load share (LS) controller design and the implementation of paralleled phase-shifted full-bridge converters (PSFBC) used in distributed power systems. By adopting the digital control strategy, separately used ICs for PSFBC and LS control functions in analog systems can be merged into a cost-effective digital controller. To compensate and stabilize both PSFBC and LS loops with the direct digital design approaches, small-signal model of the system is derived in discrete-time domain. The steady-state and dynamic load sharing performances are also investigated. Experimental results from two 1.2 kW paralleled PSFBC modules are shown to verify the proposed work.

• International Journal of Internet, Broadcasting and Communication
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• 제13권2호
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• pp.1-6
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• 2021

For competitive hotel business, the hotel must have a sound prediction capability to balance the demand and supply of hospitality products. To have a sound prediction capability in the hotel, it should be prepared to be equipped with a new technology such as quantum computing. The quantum computing is a brand new cutting-edge technology. It will change hotel business and even the whole world too. Therefore, we study the impact of quantum computing on supply chain management (SCM) and hotel performance. Toward the goal we have developed the research model including six constructs: quantum (computing) prediction, communication, supplier relationship, service quality, non-financial performance, and financial performance. The result of the study shows a significant influence of quantum (computing) prediction on hotel performance through the mediating role of SCM in the hotel. Quantum prediction is highly significant in enhancing the SCM in the hotel. However, the direct effect between the quantum prediction and hotel performance is not significant. The finding indicates that hotels which would install the quantum computing technology and utilize the quantum prediction could hugely benefit from the performance improvement.

• 한국전자파학회논문지
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• 제17권12호
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• pp.1212-1223
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• 2006

마이크로웨이브 대역은 무선 서비스의 수요가 많은 대역이지만 주로 장거리 고정 통신용으로 이용되어 전파 모델에 대한 연구가 VHF/UHF 대역보다 적게 이루어졌으나, 최근 마이크로웨이브 대역을 이용한 이동 통신 서비스가 증가됨에 따라 보다 정확성 있는 전파 예측 모델의 개발이 요구되어 왔다. 이동 전파 환경에서 신뢰성있는 전파 예측 모델을 개발하기 위해서는 다양한 전파 환경에서 신호의 반사, 회절 및 산란에 따른 전파 특성에 대한 측정 및 분석이 필요하다. 제시된 8 GHz 대역용 전파 예측 모델은 가시거리 영역과 비가시거리 영역에 맞는 모델을 구분하여 개발된다. 가시거리 영역용 예측 모델은 직접파, 지면 반사파 및 도로 양쪽 건물 반사파에 의한 해석적 결과에 측정된 경로 손실 지수를 적용하여 신호 세기를 예측하고, 비가시거리 영역용 예측 모델은 회절 후 신호 변화 현상에 대한 분석 결과를 이용하여 수신 전력을 예측한다.

• 국제지역연구
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• 제13권3호
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• pp.413-438
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• 2009

본 연구는 관광이 목적인 아웃바운드 관광객, 인바운드 관광객들의 출입국자수가 들어있는 패널 자료를 활용하여, 한국인 관광객의 해외관광수요와 외국인 관광객의 한국관광수요에 미치는 요인을 중력모형을 이용하여 분석하고자 한다. 그리고 한국인 관광객의 해외관광수요와 외국인 관광객의 한국관광수요를 비교 조사함으로써 한국의 관광발전과 관광학술연구에 기여하는데 목적을 둔다. 본 분석을 위해 한국의 관광서비스의 주요국들 간 출입국통계를 활용한다. 분석의 대상 국가는 한국의 관광서비스의 주요 교역국이며 자료의 수입이 가능한 국가이다. 이를 기준으로 본 분석에는 16개국 즉 중국, 일본, 미국, 러시아, 태국, 필리핀, 말레이시아, 베트남, 대만, 홍콩, 싱가포르, 호주, 캐나다, 영국, 독일, 프랑스가 포함 된다. 또한 2003년에서 2005년 통계자료를 대상으로 하였는데 이유는 통계자료 수집의 한계 때문이다. 특히 2006년 8월부터 출입국사무소의 목적별 출입국자수를 조사하는 통계처리 방식이 달라졌기 때문이다. 따라서 본 연구는 한국과 16개국의 관광서비스 무역통계를 이용한다. 분석을 위해 한국의 출입국통계와 무역통계 그리고 각국의 경제지표들을 활용한다. 한국의 출입국통계는 한국관광통계를 활용하고, 무역통계는 세계무역통계 자료를 그리고 각국의 인구수, GDP, GNI 등은 한국은행통계시스템 자료와 통계청통계자료를 활용한다. 그리고 양국 간 비행거리는 항공사와 여행사 사이트의 통계자료를 활용한다.

• Earthquakes and Structures
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• 제12권4호
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• pp.425-436
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• 2017

Vibration control using a tuned mass damper (TMD) is an effective technique that has been verified using analytical methods and experiments. It has been applied in mechanical, automotive, and structural applications. However, the damping of a TMD cannot be adjusted in real time. An excessive mass damper stroke may be introduced when the mass damper is subjected to a seismic excitation whose frequency content is within its operation range. The semi-active tuned mass damper (SATMD) has been proposed to solve this problem. The parameters of an SATMD can be adjusted in real time based on the measured structural responses and an appropriate control law. In this study, a stiffness-controllable TMD, called a leverage-type stiffness-controllable mass damper (LSCMD), is proposed and fabricated to verify its feasibility. The LSCMD contains a simple leverage mechanism and its stiffness can be altered by adjusting the pivot position. To determine the pivot position of the LSCMD in real time, a discrete-time direct output-feedback active control law that considers delay time is implemented. Moreover, an identification test for the transfer function of the pivot driving and control systems is proposed. The identification results demonstrate the target displacement can be achieved by the pivot displacement in 0-2 Hz range and the control delay time is about 0.1 s. A shaking-table test has been conducted to verify the theory and feasibility of the LSCMD. The comparisons of experimental and theoretical results of the LSCMD system show good consistency. It is shown that dynamic behavior of the LSCMD can be simulated correctly by the theoretical model and that the stiffness can be properly adjusted by the pivot position. Comparisons of experimental results of the LSCMD and passive TMD show the LSCMD with less demand on the mass damper stroke than that for the passive TMD.

• 한국태양에너지학회 논문집
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• 제32권2호
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• pp.42-49
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• 2012

In this article, the author carried out a theoretical study on the application techniques of a new Combined Passive Solar System (hereinafter referred to as the CPSS) of direct gain and trombe walls to get quick morning heating and to prevent afternoon overheating for office building. The numerical model proposed in this study can be used for the performance analysis of the CPSS in the winter and summer. Heating and Cooling loads are analysed for building energy consumption reduction using this numerical model. The results indicate that CPSS in the winter and summer modes could provide profitable conditions for improvement of indoor thermal comfort control and energy saving. consequently, the application of CPSS will not lead to significant reductions in the auxiliary air conditioning demand but also realize the environmentally friendly building.

• 가정과삶의질연구
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• 제7권1호
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• pp.15-25
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• 1989

The purpose of this study is to examine the factors affecting the consumer's search for information and the relationship between the amount of search and the final price paid. The model indicates the demand for search is affected by the market price of each durable good purchased, the tim available for search, family income, direct cost of search, the initial stock of information, effectiveness of search, and shopping attitudes. The final price savings are a function of search, price of dispersion in the market, the initial stock of information, and effectiveness of search. Data from the Pane Study on Consumer Decisions and Asset Management were used for the empirical testing of the theoretical model. The amount of information search as dependent variable is represented by two different measures, the level of discussion with others and the number of stores visited. The amount of discussion with others depends mainly on the respondent's shopping attitude. The higher the wife's desire to search, the higher the degree of husband's comparison shopping, the less the husband's perception of price-quality relationship, the higher the level of discussions with others. The number of stores visited depends on the average market price of product purchased and the level of family income. The higher the average market price and he higher the level of family income, the greater the number of stores visited. The final savings depend upon the level of information search. The greater the number of store visited, but the less the purchase is discussed with stores, the higher the final savings are.

• 대한가정학회지
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• 제29권4호
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• pp.151-165
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• 1991

The purpose of this study was to examine causal model of resources and demands, family financial management and subjective financial security among urban households based on system theory. For this purpose, the data were collected by the questionnaire sheets. 455 housewives participated this survey in Seoul. And the data were analyzed by various statistical methods such as Frequency, Percentile, ANOVA, F-test, Pearson's correlation analysis, Multipe Regression Analysis, and Path Analysis. The results of this research were as follows: 1. There were significant differences in the Subjective Financial Security according to resource variables and demand yariables. Those variables were such as housewive's age, education, occupation, househead's occupation, per capita income, aspiration, expectancy, perception of financial progress and relative deprivation. 2. The higher family financial management level, the higher level of Subjective Financial security. And the higher family financial management plan·implement level, the higher level of Subjective Financial security. 3. The lower debt/asset ratio, the higher level of Subjective Financial security. 4. Aspiration, per capita income an financial managemant variables showed direct effect on Subjective Financial security among all variables affecting the urban households' Subjective financial security. While housewive's education level, aspiration, per capita income and husband's occupation affected indirectly on the Subjective Financial security through family financial managemant.

• Industrial Engineering and Management Systems
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• 제13권2호
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• pp.163-171
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• 2014

Under amazing increase in markets and certain demand on qualified service in the delivery system, global logistic optimization is becoming a keen interest to provide an essential infrastructure coping with modern competitive prospects. As a key technology for such deployment, we have been engaged in the practical studies on vehicle routing problem (VRP) in terms of Weber model, and developed a hybrid approach of meta-heuristic methods and the graph algorithm of minimum cost flow problem. This paper extends such idea to multi-depot VRP so that we can give a more general framework available for various real world applications including those in green or low carbon logistics. We show the developed procedure can handle various types of problem, i.e., delivery, direct pickup, and drop by pickup problems in a common framework. Numerical experiments have been carried out to validate the effectiveness of the proposed method. Moreover, to enhance usability of the method, Google Maps API is applied to retrieve real distance data and visualize the numerical result on the map.

• International Journal of Computer Science & Network Security
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• 제21권6호
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• pp.222-230
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• 2021

Mobile wallets have been in continuous demand and developed over the past few years, especially during the COVID-19 pandemic. Several studies have examined user intentions and perspectives. This study develops a conceptual model combining behavioral factors with the technology acceptance model (TAM). The goal is to identify key factors that influence user's intention to adopt mobile payments. This study uses the TAM and the unified theory of acceptance and use of technology (UTAUT) models with additional factors. The additional factors are security, trust, facilitating conditions, and lifestyle compatibility. The study analyzes the results of a survey of 394 Saudi citizens conducted via an online survey. The results indicate that user attitudes and intentions are positively influenced by all of the factors. Perceived usefulness, perceived ease of use, lifestyle compatibility, and facilitating conditions are direct predictors of user behavior in accepting mobile wallet payments. This study provides an empirical contribution to the literature on mobile payment acceptance on the effect of perceived usefulness and lifestyle compatibility. The results demonstrate that about 26% of the respondents started using mobile wallet services because of the COVID-19 pandemic.