• 한국실내디자인학회논문집
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• 제21호
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• pp.101-106
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• 1999

This study has been designed to explore the preferences of interior space for those living in apartment housing. It also examines the relationships between preferences of interior space, such as storage space, organization type of LDK(the living room, the dining room, and kitchen), space facing south, an interior garden, the concept of each room and the characteristics of the consumers, such as age, educational background employment status of homemakers, occupation of the primary income provider, family-life cycle, total household income, the size of floor space, and homeownership. In conclusion, this study suggests that at the time of designing apartment housing units, serious consideration should be given to the built-in closets or storage space in the anbang and to the location of a child's room facing to the south of the dwelling, especially for the families with a child attending primary school or younger and higher education level of homemaker. This study also recommends that the organization of the living room, the dining room, and the kitchen should be varied according to the housing size and the age of homemaker.

• 산업경영시스템학회지
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• 제35권4호
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• pp.162-170
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• 2012

We propose a new priority discipline called the strict T-preemptive priority discipline, and derive the waiting time distributions of each class in the strict T-preemptive priority M/G/1 queue. Using this queueing analysis, we evaluate the performance of an opportunistic spectrum access in cognitive radio networks, where a communication channel is divided into time slots, a licensed primary user is assigned to one channel, and multiple unlicensed secondary users may opportunistically exploit time slots unused by the primary user. We also present a numerical example of the analysis of the opportunistic spectrum access where the arrival rates and service times distributions of each users are identical.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제9권11호
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• pp.4720-4738
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• 2015

Proper management on user-driven virtual circuits (VCs) is essential for seamless operation of virtual networks. The Network Provisioning System (NPS) is useful software for creating user-driven VCs automatically and must take fault management into account for physical layer impairments on user-driven VCs. This paper addresses a user-driven and trusty protection management in an NPS with an open standard Network Service Interface (NSI), as a contribution to show how to implement the user-driven and trusty protection management required for user-driven VCs. In particular, it provides a RESTful web service Interface for Configuration and Event management (RICE) that enable management of a distinguished data and control plane VC status between Network Service Agents (NSAs) in the event of a node or link fault and repair in a domain. This capability represents a contribution to show how network and protection events in a domain can be monitored between NSAs (NPSs with the NSI) in multiple domains. The implemented NPS controls and manages both the primary and backup VC with disjoint path in a user-driven manner. A demonstration to verify RICE API's capability is addressed for the trusty protection in the dynamic VC network.

• 한국통신학회논문지
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• 제38B권10호
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• pp.832-842
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• 2013

Cognitive Radio has attracted intensive interests of the researchers, recently. The data rate always increases in the emerging technologies. The increased data rate poses mainly two challenges for spectrum sensing. One is that the state of primary user (PU) is fast and alternatively varying between "on/off" in a spectrum sensing window. The other is that the asynchronicity among the reports in a cooperative spectrum sensing setting becomes more apparent. Both of them would deteriorate the spectrum sensing performance. Thus, we propose an asynchronous cooperative spectrum sensing method to cope with these two challenges. A likelihood ratio test based spectrum sensing is developed for a single cooperator. The likelihood ratio is obtained in the setting of fast varying PU state. The likelihood ratio test is uniformly powerful according to the Neyman-pearson lemma. Furthermore, the asynchronicity among the cooperators are studied. Two sets of fusion weights are discussed for the asynchronous time among cooperators. One is designed based on the condition probability of the PU state variation and the other one is designed based on the queueing theory. The simulation results are provided with different fusion methods. The performance improvements are demonstrated.

• 대한산업공학회지
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• 제35권1호
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• pp.109-118
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• 2009

While driving, the manual use of a mobile phone is heavily restricted due to the interference with the primary driving task. An alternative would be the use of speech interface. The current study aims to provide a guideline to implementation of a speech interface to the mobile phone. To do so, an expert evaluation was made and it revealed that a speech interface requires less workload, less performance degradation of the driving task than that of the keypad interface. To make speech interfaces more usable, new improvements are suggested. Subjective workload can be reduced and user satisfaction can be improved without degrading the primary task performance, for instance, by letting the user interrupt the speech of the phone, eliminating the repetitive words, letting the user know clearly what makes an error, providing a way to go back to the previous state, reducing the usage of keypad buttons and reducing the amount of the information on the screen.

• Asia pacific journal of information systems
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• 제29권3호
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• pp.328-358
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• 2019

Business-to-Business electronic commerce websites are a common form of inter-organizational systems that span organizational boundaries and enables organizations to exchange information in a seamless fashion. To reap the desired benefits it is important that the website be used in the intended manner. The level and extent of use of a business-to-business website depends partly on the inclination to use the website by the users in the primary organization and in the user organizations independently and the combined inclination of the organizations together. This combined inclination is referred to as the System Inclination, with dominance playing a key role. Each organization has certain characteristics of its own and may differ significantly in their inclination to use. It is important to analyze the factors that determine this inclination to use, so that organizations can adopt appropriate management mechanisms to control it. This paper proposes a framework to explain the organizational factors and their influence on the inclination to use a website, based on study of four Indian buyer-supplier dyads. Inclination to use is found to be influenced by factors like top management support, website characteristics, adequate support mechanisms, user group orientation towards electronic commerce and basic IT drive among the employees, at both the primary and user organizations.

• 한국콘텐츠학회논문지
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• 제4권3호
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• pp.21-40
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• 2004

무역포탈사이트는 중소기업들이 최신의 정보와 통신기술을 통해 효율적으로 국제무역활동을 할 수 있게 하는 도구중 하나라고 할 수 있다. 따라서 중소기업들의 수출경쟁력 제고를 위해서는 무역포탈사이트를 적극적으로 활용할 필요가 있다. 이와 관련하여 본 논문은 기존의 서비스품질에 관한 문헌과 정보기술 이용만족도에 관한 연구 검토를 통해 무역포탈사이트를 사용하는데 있어 이용자들의 만족 요인을 분석하였다. 실증 연구를 위해 서비스품질, 정부정책, 기술, 기업, 비용이 이용만족도에 영향을 미치고 이용만족도는 향후 지속적 이용의도에 영향을 미치는 것으로 연구모형을 설정하였다. 대표적인 무역포탈사이트 이용자들에 대한 실종분석 결과 서비스품질, 정부정책, 비용이 이용자만족에 유의한 영향을 미치고, 이용자 이용만족은 지속적 사용의도에 유의적인 영향을 미치는 것으로 나타났다. 이러한 분석 결과는 기업의 무역포탈사이트 관리자, 전자무역시스템개발자, 정부정책자 등에게 여러 가지 시사점을 제공하고 있다.

• 한국통신학회논문지
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• 제40권2호
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• pp.253-263
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• 2015

최근 다수의 후 순위 사용자(Secondary User)가 각각의 검출 결과를 융합 센터(Fusion Center)에 보고하여 대역 검출의 성능을 향상시키기 위한 협력 대역 검출 기법이 이루어지고 있다. 또한 선 순위 사용자(Primary User)에게 할당된 주파수 대역을 융합 센터가 공유하는 인지 무선(Cognitive Radio)기술이 개발되고 있다. 이 논문에서는 분산 협력 대역 검출 환경에서 후 순위 사용자의 검출 정보가 융합 센터로 보고되는 채널의 오류 확률을 고려한 기존 분산 협력 대역 검출 기법의 성능 저하를 보완하는 새로운 분산 협력 대역 검출 기법을 제안하였다. 또한 분산 협력 대역 검출 기법의 오류 확률을 최소화 하는 검출 문턱값의 최적화 방법을 수식의 유도를 통해 제안하였다. 최적의 검출 문턱값은 분산 협력 대역 검출의 성능을 최대화 하는 것을 확인하였다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제7권9호
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• pp.2081-2100
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• 2013

In this paper, we propose a cooperative hybrid spectrum sharing protocol by jointly considering interweave (opportunistic) and underlay schemes. In the proposed protocol, secondary users can access the licensed spectrum along with the primary system. Our network scenario comprises a single primary transmitter-receiver (PTx-PRx) pair and a group of M secondary transmitter-receiver (STx-SRx) pairs within the transmission range of the primary system. Secondary transmitters are divided into two groups: active and inactive. A secondary transmitter that gets an opportunity to access the secondary spectrum is called "active". One of the idle or inactive secondary transmitters that achieves the primary request target rate $R_{PT}$ will be selected as a best decode-and-forward (DF) relay (Re) to forward the primary information when the data rate of the direct link between PTx and PRx falls below $R_{PT}$. We investigate the ergodic capacity and outage probability of the primary system with cooperative relaying and outage probability of the secondary system. Our theoretical and simulation results show that both the primary and secondary systems are able to achieve performance improvement in terms of outage probability. It is also shown that ergodic capacity and outage probability improve when the active secondary transmitter is located farther away from the PRx.

• Journal of Communications and Networks
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• 제14권5호
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• pp.471-480
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• 2012

Reliable detection of primary user activity increases the opportunity to access temporarily unused bands and prevents harmful interference to the primary system. By extracting a global decision from local sensing results, cooperative sensing achieves high reliability against multipath fading. For the effective combining of sensing results, which is generalized by a likelihood ratio test, the fusion center should learn some parameters, such as the probabilities of primary transmission, false alarm, and detection at the local sensors. During the training period in supervised learning, the on/off log of primary transmission serves as the output label of decision statistics from the local sensor. In this paper, we extend unsupervised learning techniques with an expectation maximization algorithm for cooperative spectrum sensing, which does not require an external primary transmission log. Local sensors report binary hard decisions to the fusion center and adjust their operating points to enhance learning performance. Increasing the number of sensors, the joint-expectation step makes a confident classification on the primary transmission as in the supervised learning. Thereby, the proposed scheme provides accurate parameter estimates and a fast convergence rate even in low signal-to-noise ratio regimes, where the primary signal is dominated by the noise at the local sensors.