• Korean Institute of Interior Design Journal
• /
• no.21
• /
• pp.101-106
• /
• 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.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.35 no.4
• /
• pp.162-170
• /
• 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)
• /
• v.9 no.11
• /
• pp.4720-4738
• /
• 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.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.38B no.10
• /
• pp.832-842
• /
• 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.

• Journal of Korean Institute of Industrial Engineers
• /
• v.35 no.1
• /
• pp.109-118
• /
• 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
• /
• v.29 no.3
• /
• pp.328-358
• /
• 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.

• The Journal of the Korea Contents Association
• /
• v.4 no.3
• /
• pp.21-40
• /
• 2004

Trade portal site is one of the tools which make it possible for small and medium-sized enterprises(SMEs) to manage international trade activities more efficiently by using the newest information and telecommunication technology. So Korean SMEs should utilize trade portal sites more actively to promote global competitive power. Based on the theory of service quality and existing researches related to using information technology, this paper analyzed the primary factors which affect user's utilization satisfaction in using trade portal sites. According to the results of the empirical study on actual users of the representative trade portal sites by multiple regression analysis, the primary factors, such as service quality, government policy and cost factor have affected user's utilization satisfaction in using trade portal sites. And user's utilization satisfaction have positive effect on continuous using intention. These research results will provide many useful insights to trade portal site managers, e-trade system developers and government policy makers.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.40 no.2
• /
• pp.253-263
• /
• 2015

Lately, spectrum sensing performance has been improved by using cooperate spectrum sensing which each results of sensing of several secondary users are reported to the fusion center. Using Cognitive Radio, secondary user is able to share a bandwidth allocated to primary user. In this paper, we propose a new decentralized cooperative spectrum sensing scheme which compensates the performance degradation of existing decentralized cooperative spectrum sensing considering the error probability of the channel which sensed result of the secondary user is delivered to the fusion center in decentralized cooperative spectrum sensing. In addition, a sensing threshold optimization of minimizing the error probability of decentralized cooperative spectrum sensing is introduced by deriving the equation and the optimal sensing threshold has been confirmed to maximize the decentralized cooperative spectrum sensing performance.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.7 no.9
• /
• pp.2081-2100
• /
• 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
• /
• v.14 no.5
• /
• pp.471-480
• /
• 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.