• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.2C
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• pp.229-237
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• 2010

The conventional detection methods developed for spatially-multiplexed MIMO systems such as OSIC and QRD-M show performance difference for each user depending on the order of detection when they are applied to detection of multi-user signals in uplink multiuser systems based on collaborative spatial multiplexing. In this paper, a signal detection method for uplink multiuser systems based on collaborative spatial multiplexing is proposed to provide similar performance for each user while its performance is close to the case of ML detection. Compared with QRD-M method, computational complexity of the proposed signal detection method is similar in the case of QPSK, and significantly lower in the case of high modulation order with 16-QAM and 64-QAM.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.8C
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• pp.713-719
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• 2010

Collaborative spectrum sensing has been found to be an effective means for detecting the activity of primary users in a fading environment. Most previous works on collaborative spectrum sensing are based on the assumption that the local spectrum sensing decisions of secondary users are statistically independent. However, it may not hold in some practical situations. In this paper, we consider a cognitive radio network where the local spectrum sensing decisions of secondary users are statistically correlated with the same level of correlation if they are next to each other in location and statistically independent, otherwise. Then, for the system, we analyzed the performance of the collaborative spectrum sensing with the AND and the OR fusion rules and found that the scheme with the AND fusion rule performs better than the one with OR fusion rule when the degree of correlation is significant.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.7C
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• pp.642-650
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• 2010

Collaborative spectrum sensing allows secondary users scattered in location to work together to detect the activity of primary users and has been shown to significantly reduce the performance degradation due to fading phenomenon. Most previous works on collaborative spectrum sensing are based on the assumption that local spectrum sensing decisions of secondary users are statistically independent. However, it may not hold in some practical situations with shadowing effect. In this paper, we consider the case that the secondary users are evenly spaced in the form of a linear array and only adjacent secondary users are statistically correlated, and analyze the effect of the statistical correlation on the performance of collaborative spectrum sensing and the throughput of a cognitive radio network. Here we assumed the AND and OR fusion rules for combining the local decisions of secondary users. The analysis showed that the AND fusion rule achieves higher throughput than the OR fusion rule.

• Communications of the Korean Institute of Information Scientists and Engineers
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• v.24 no.12 s.211
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• pp.84-91
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• 2006

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.10C
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• pp.1015-1026
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• 2002

As per increasing research interest in the field of collaborative computing in recent year, the importance of security issues on that area is also incrementally growing. Generally, the persistency of collaborative system is facilitated with conventional authentication and cryptography schemes. It is however, hard to meet the access control requirements of distributed collaborative computing environments by means of merely apply the existing access control mechanisms. The distributed collaborative system must consider the network openness, and various type of subjects and objects while, the existing access control schemes consider only some of the access control elements such as identity, rule, and role. However, this may cause the state of security level alteration phenomenon. In order to handle proper access control in collaborative system, various types of access control elements such as identity, role, group, degree of security, degree of integrity, and permission should be taken into account. Futhermore, if we simply define all the necessary access control elements to implement access control algorithm, then collaborative system consequently should consider too many available objects which in consequence, may lead drastic degradation of system performance. In order to improve the state problems, we propose a novel access control framework that is suitable for the distributed collaborative computing environments. The proposed scheme defines several different types of object elements for the accessed objects and subjects, and use them to implement access control which allows us to guarantee more solid access control. Futhermore, the objects are distinguished by three categories based on the characteristics of the object elements, and the proposed algorithm is implemented by the classified objects which lead to improve the systems' performance. Also, the proposed method can support scalability compared to the conventional one. Our simulation study shows that the performance results are almost similar to the two cases; one for the collaborative system has the proposed access control scheme, and the other for it has not.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.12B
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• pp.2283-2291
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• 1999

Most of collaborative applications use the Server-Client paradigm where all requests of clients will be delivered first to server and that server distributes again the requests to the rest of clients. This server-oriented operation and data transmission mechanism always presents end-to-end communications between the server and clients that can notably decrease the overall performance of applications. In this paper, we propose a new design approach to inhibit the inefficiency of applications using active networking concepts. We propose the ASM service that offers an application-specific in-network multicast functions, the AMTC service and its tree algorithm that builds anon-core based shared tree for multicast. These proposed services locate in active nodes performing its services as part of the overall system to improve the performance of collaborative applications.

• Journal of Society of Preventive Korean Medicine
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• v.12 no.1
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• pp.49-60
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• 2008

This study investigated the Oriental medicine knowledge and educational requirement of medical staff working in Oriental-Western collaborative medicine hospitals(except for Oriental and Western medicine doctors) based on the recognition that not only mutual understanding and cooperation between Oriental and Western medicine doctors but also the knowledge of Oriental medicine of medical support staff such as nurses, medical technologists, pharmacists and administrative staff are very important to promote Oriental-Western collaborative medical treatment. The study results are summarized as follows : First, it was found that the ratio of nurses who took Oriental medicine education was much higher than those of other groups. They took Oriental medicine education in the types of school curriculum (27.0%) and special lectures in workplace(20.4%). Second, many of the people who took Oriental medicine education were found to be not satisfied with the education in general - 32.7% of them answered the education content was "so so" and 48.4% of them answered "unsatisfactory." Third, the general necessity of Oriental medicine education was found to be an average of 3.60 out of 5, and the number was higher "after employment"(average=3.85) than "before employment"(average=3.04). Fourth, the study found that Oriental-Western collaborative medicine hospital staff are well aware of the necessity of the knowledge of Oriental medicine in the cases of communications between different occupational types, consultations with patients or their guardians, treatment and nursing and the establishment of the practice of specialized Oriental medicine institutes. Fifth, the levels of Oriental medicine knowledge showed a difference in average value according to the role range(p<0.000), and it was found that there is an interaction effect between occupation type and role range(p<0.015).

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.9B
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• pp.1049-1056
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• 2011

In the field of document editing, a real-time collaborative editing that multiple users edit a same document simultaneously has been actively studied. The co-editing session should be kept for the synchronization about the changes during the real-time collaborative editing of documents among the participants. If the session ends during collaborative editing, they wouldn't be able to continue co-editing anymore. The purpose of this study is to develop a framework for Continuous Real-time Collaborative Editing that disconnects the session in unintended situations. Participants should be able to terminate editing at any time in opened co-editing session, and certain participant is able to disconnected because of unstable networks. In this case, the editing session should be maintained without termination.

• Journal of the Korea Society of Computer and Information
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• v.13 no.5
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• pp.143-154
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• 2008

As internet users swiftly increased in number, both collaborations and communications on the Internet gradually increased. Accordingly, the importance of individualized service has been raised as user-centered service has been activated. As of now, there are many systems supporting collaboration based on the Web. Unfortunately, since the existing Web-based collaborative systems do not support individualized service, they do not provide effective collaboration for various kinds of users. In this paper, we describe the development of a collaboration portlet for the CoSlide collaborative system. The collaboration portlet provides various methods which control the resources of each workspace on the CoSlide server. As a component of a portal, the developed portlet provides effective collaborative environment satisfying various user requirements. Users can collaborate through the individualized interfaces which are composed by portlets on a portal for their own working environment.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.5
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• pp.914-923
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• 2015

Recently, as the number of smart devices (such as smart TV or Web based IPTV) increases, the way of digital broadcast contents is changed. This change leads that conventional broadcast media accepts Web platform and its services to provide more quality contents. Based on this change, in education field, education broadcasting also follows the trend. The traditional education broadcasting platforms, which just delivered the lecture in one-way, are utilized the Web technology to make interaction between teacher and student. Current education platforms, however, are insufficient to satisfy users' demands for two-way interactions. This paper proposes a new remote collaborative learning platform which able to provide high interactivity among users. Based on new functional requirements from original use case, the platform provides collaborative contents sharing and collaborative video streaming techniques by utilizing WebRTC (Web Real-Time Communication) technology. The implementation demonstrates the operability of proposed system.