• Journal of Communications and Networks
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• 제8권2호
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• pp.151-157
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• 2006

In a continuously expanding wireless world, the number of radio systems increases every day and efficient spectrum usage becomes a more significant requirement. Ultra-wideband (UWB) and cognitive radio are two exciting technologies that offer new approaches to the spectrum usage. The main objective of this paper is to shed the first light on the marriage of these two important approaches. The strength of orthogonal frequency division multiplexing (OFDM) based UWB in co-existing with licensed systems is investigated. The opportunity concept is defined, and the requirements of the opportunistic spectrum usage are explained. It is proposed to take the UWB-OFDM from the current underlay implementation, and evolve it to a combined underlay and opportunistic spectrum usage technology, leading to cognitive UWB-OFDM. This way, we aim at making UWB more competitive in the wireless market with extended range, higher capacity, better performance, and a wide variety of applications.

• 디지털산업정보학회논문지
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• 제12권4호
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• pp.135-143
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• 2016

The purpose of this study is to investigate the user's attitude and usage of smart banking application in terms of user's benefits and personalization. While the prior researches on mobile banking adoption focus on the characteristics of service itself, this paper intends to investigate the smart banking application in terms of user's benefits, which are personal value consumers attach to the product or service attributes. Based on prior studies functional benefits, social benefits, experiential benefits, and personalization are identified as affecting factors of the user's attitude and usage of smart banking application. According to the results of multiple regression analysis, all benefit factors(functional benefit, experimental benefit, social benefit) and personalization were found to be significantly related to the user's attitude. Users' attitude on smart banking was found to be significantly related to the real usage as well. This paper has value in that it investigates the attitude and usage of smart banking in terms of benefits.

• 한국산업정보학회:학술대회논문집
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• 한국산업정보학회 2003년도 추계공동학술대회
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• pp.251-275
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• 2003

Given the importance of adoption of the IOS (Interorganizational System) and the “much-slower-than-anticipated” growth of IOS adoption, especially in small- and midium firms, this study aimed to identify the key determinants of small- and midium-sized firms' ISO usage. Based on prior research on IT/EDI adoption in various organizations, the model that incorporates 9 factors that are hypothesized to have influence on the ISO usage decision was developed and empirically tested against data collected from 114 small- and midium-seized firms' top management. The results show that perceived financial costs are found to be major impediments to usage intention, and perceptions of relative advantage, compatibility, risk are also important determinants of ISO usage intention in small- and midium-sized firms. Implications of these findings are duscussed for researchers and practitioners.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.158-163
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• 2005

Competitive electricity markets necessitate equitable methods for allocating transmission usage in order to set transmission usage charges and congestion charges in an unbiased and an open-accessed basis. So in competitive markets it is usually necessary to trace the contribution of each participant to line usage, congestion charges and transmission losses, and then to calculate charges based on these contributions. A UPFC offers flexible power system control, and has the powerful advantage of providing, simultaneously and independently, real-time control of voltage, impedance and phase angle, which are the basic power system parameters on which sys-tem performance depends. Therefore, UPFC can be used efficiently and flexibly to optimize line utilization and increase system capability and to enhance transmission stability and dampen system oscillations. In this paper, a mathematical approach to allocate the contributions of system users and UPFCs to transmission system usage is presented. The paper uses a dc-based load flow modeling of UPFC-inserted transmission lines in which the injection model of the UPFC is used. The relationships presented in the paper showed modified distribution factors that modeled impact of utilizing UPFCs on line flows and system usage. The derived relationships show how bus voltage angles are attributed to each of changes in generation, injections of UPFC, and changes in admittance matrix caused by inserting UPFCs in lines. The relationships derived are applied to two test systems. The results illustrate how transmission usage would be affected when UPFC is utilized. The relationships derived can be adopted for the purpose of allocating usage and payments to users of transmission network and owners of UPFCs used in the network. The relationships can be modified or extended for other control devices.

• 디지털융복합연구
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• 제10권11호
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• pp.343-349
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• 2012

사용 조절 모델은 보호된 컨텐츠의 사용에 대한 포괄적인 기술을 허용하는 새로운 접근 조절 모델의 시초이다. 이 범례에서 객체로의 접근에 관련된 결정은 요청 시간에만 제한되어있지 않다. 그것은 보호된 객체의 사용과 결합되며 사용과 병렬식으로 진행되는 지속적 처리가 된다. 사용 조절의 실현은 오랫동안 보안 문서의 전파에 있어서 조절 능력을 잃게 되는 문제를 해결하려한 연구 과제이다. 클라우드 컴퓨팅의 발현으로 문서들이 클라우드에 저장이 되고 문서를 보거나 편집할 수 있는 프로세서들이 클라우드안에 상주하며 문서들은 브라우저와 같은 신 클라이언트에 의해 접근이 가능해진다. 우리는 그러한 시나리오가 이해 당사자의 정책에 기반을 둔 문서 사용 보안에 대한 사용 조절의 실행에 있어 이상적인 기회를 제공하는 사실에 주목한다. 본 논문에서는 클라우드 기반의 어플리케이션에서 더 나은 멀티미디어 컨텐츠를 실행하기 위한 멀티미디어 컨텐츠 관리(MCM)를 제안한다. 그리고 클라우드 컴퓨터의 발현과 사용을 통해 보안된 객체의 사용에 있어 매끄러운 조절을 제공하기 위한 강력한 구성을 설계한다. 우리는 이러한 실현을 위해 설계 원칙을 기술하고 제안 구조를 논한다.

• 한국IT서비스학회지
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• 제13권4호
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• pp.289-308
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• 2014

Mobile instant messaging (MIM) has been widely used in modern society due to its portability, speed and ease of use. In addition to simple text-based messaging, mobile instant message has now expanded to include graphics, images, and video. Many instant message service providers attempt to differentiate their service by providing an unique emoticon. Therefore, understanding the factors that affecting the continuous usage of emoticon is essential to capture users' interest. There is relatively little study on emoticon in information systems field. Hence, this study attempts to explore the continuous usage of emoticon through exploring the property of emoticon and usage motivation of emoticon. Based on the results, this study attempts to demonstrate practical implication of marketing on understanding user interest to mobile instant messenger service provider.

• 대한임베디드공학회논문지
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• 제6권1호
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• pp.32-40
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• 2011

For a NAND booting based embedded system, an application program on the NAND flash memory is downloaded to the RAM when the system is booted. In this case, the application program exists in both the RAM and the NAND flash so the RAM usage is increased. In this paper, we suggested the demand paging technique for the decreasing of the RAM usage for OS-less NAND booting based embedded systems. As a result of a benchmark test, 40~80% of the code memory usage was reduced with below 5% of execution time delay.

• 한국정보시스템학회지:정보시스템연구
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• 제19권3호
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• pp.35-58
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• 2010

Portal sites have been providing diverse services to attract new users and retain existing customers. Recently, they also added new services and increased quality of the services they provide to secure more customers. It is, however, not clear how people actually react to such activities. We wanted to understand the mechanism associated with users' continued usage intention of current Portal site. We assumed search, e-mail, information, community, e-commerce services as key services provided by most Portal sites and considered valuable by many customers. The quality of these services may directly affect users' continued usage intention. However, we can also assume that attractive alternatives and switching cost may have some influence on users' continued usage intention. Therefore, in this study, key variables pertaining to the quality of key services provided by Portal sites, attractive alternatives, and switching cost were examined to explain the dynamics of users' continued usage intention. An empirical study based on 891 survey responses showed the importance of the quality of key services for users' continued usage intention. Switching cost also demonstrated strong association with users' continued usage intention. However, attractive alternatives did not show a significant association with users' continued usage intention. We also found that the variable attractive alternatives moderated the relationship between the quality of search service and users' continued usage intention and the relationship between the quality of information service and users' continued usage intention. On the other hand, the variable switching cost showed a moderating effect on the relationship between the quality of e-mail service and users' continued usage intention and the relationship between the quality of community service and users' continued usage intention. This study implies that Portal sites need to make efforts not only to improve the quality of key services but also to consider attractiveness of other Portal sites' services and switching cost to secure more customers.

• 한국IT서비스학회지
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• 제7권4호
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• pp.21-43
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• 2008

This paper develops the research model for the understanding of learner's usage intention in web based collaborative learning(WBCL) system. This model is based on the Davis' Technology Acceptance Model(TAM) and Social Interactivity Theory. Data is collected 225 University students from two different institutions. They were divided into 46 groups and asked to complete an online TOEIC preparation module using WBCL systems over 4 weeks. Data were collected at three points for each participant-before, 3 weeks after, and at the end of the online module. The result show that TAM based Belief factors(Usefulness, Ease of use, Playfulenss) are important determinants of usage intention in WBCL systems. The study also found the external factors of the extended TAM to be subjective norm, leader's enthusiasm in WBCL context.

• 한국정보과학회논문지:컴퓨팅의 실제 및 레터
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• 제14권1호
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• pp.63-70
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• 2008

휴대폰 사용이 대중화됨에 따라 사람들이 때와 장소를 가지리 않고 휴대폰을 무분별하게 사용함으로써 나타나는 폐해가 심각하다. 특히, 휴대폰 사용이 병원의 전자 의료기기나 항공기 이착륙 시스템 등에 나쁜 영향을 끼친다는 연구 결과들이 발표되고 있다. 본 논문에서는 모바일 기기에 적용할 수 있는 상황인식 기반의 사용제어 모델을 제안한다. 즉, 위치와 시간, 주변소음 등의 상황정보에 따라 휴대폰 자체 및 모바일 콘텐츠의 사용을 제어하는 모델에 대해 연구하였다. 제안한 사용제어 모델은 '동적인 역할기반 접근제어' (Dynamic Role-based Access Control)을 포함한다. 제안한 시스템의 효용성을 확인하기 위해, PC 서버 및 임베디드 보드 상에 프로토타입 시스템을 구현하여 그 성능을 평가하였다.