• KSII Transactions on Internet and Information Systems (TIIS)
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• 제12권11호
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• pp.5344-5356
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• 2018

Nowadays with the help of Location-Based Social Networks (LBSNs), users of Point-of-Interest (POI) recommendation service in LBSNs are able to publish their geo-tagged information and physical locations in the form of sign-ups and share their experiences with friends on POI, which can help users to explore new areas and discover new points-of-interest, and promote advertisers to push mobile ads to target users. POI recommendation service in LBSNs is attracting more and more attention from all over the world. Due to the sparsity of users' activity history data set and the aggregation characteristics of sign-in area, conventional recommendation algorithms usually suffer from low accuracy. To address this problem, this paper proposes a new recommendation algorithm based on a novel Preference-Content-Region Model (PCRM). In this new algorithm, three kinds of information, that is, user's preferences, content of the Point-of-Interest and region of the user's activity are considered, helping users obtain ideal recommendation service everywhere. We demonstrate that our algorithm is more effective than existing algorithms through extensive experiments based on an open Eventbrite data set.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제15권1호
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• pp.302-322
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• 2021

In the system of ciphertext policy attribute-based encryption (CP-ABE), only when the attributes of data user meets the access structure established by the encrypter, the data user can perform decryption operation. So CP-ABE has been widely used in personal health record system (PHR). However, the problem of key abuse consists in the CP-ABE system. The semi-trusted authority or the authorized user to access the system may disclose the key because of personal interests, resulting in illegal users accessing the system. Consequently, aiming at two kinds of existing key abuse problems: (1) semi-trusted authority redistributes keys to unauthorized users, (2) authorized users disclose keys to unauthorized users, we put forward a CP-ABE scheme that has authority accountability, user traceability and supports arbitrary monotonous access structures. Specifically, we employ an auditor to make a fair ruling on the malicious behavior of users. Besides, to solve the problem of user leaving from the system, we use an indirect revocation method based on trust tree to implement user revocation. Compared with other existing schemes, we found that our solution achieved user revocation at an acceptable time cost. In addition, our scheme is proved to be fully secure in the standard model.

• International Journal of Computer Science & Network Security
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• 제22권2호
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• pp.327-333
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• 2022

Internet Protocol Television (IPTV) has emerged as a personal entertainment source for home users. Streaming IPTV content over a wireless medium with good Quality of Service (QoS) can be a challenging task as IPTV content requires more bandwidth and Wireless Local Area Networks (WLANs) are susceptible to packet loss, delay and jitter. This research presents the capacity of IPTV using User Datagram Protocol (UDP) and TCP Friendly Rate Control (TFRC) over IEEE 802.11ac WLANs in good and bad network conditions. Experimental results show that in good network conditions, UDP and TFRC could accommodate a maximum of 78 and 75 Standard Definition Television (SDTV) users, respectively. In contrast, 15 and 11 High-Definition Television (HDTV) users were supported by UDP and TFRC, respectively. Performance of UDP and TFRC was identical in bad network conditions and same number of SDTV and HDTV users were supported by TFRC and UDP. With background Transmission Control Protocol (TCP) traffic, both UDP and TFRC can support nearly the same number of SDTV users. It was found that TFRC can co-exist fairly with TCP by giving more throughput to TCP unlike UDP.

• 한국경영과학회지
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• 제28권1호
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• pp.63-77
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• 2003

Group buying is one of the most popular transaction patterns on the internet at least in Korea. Nevertheless, it is hard to find academic researches for it in view of consumer behavior. In this paper, we analyze factors which determine consumer's attitude toward and intention of participation in Internet group buying by comparison of Internet individual one. For this purpose, we propose “lowering price”, “decreasing risk” and “reducing transaction cost” as relative advantages and "lack of product assortment" and "delay of time" as relative disadvantages over individual buying on the Internet. For empirical test, Internet users who have some experiences of individual buying but not group ones on the Internet are surveyed and analyzed. In result, a satisfying model fitness for structural equation model is derived and most hypotheses except the relationship between "decreasing risk" and "attitude toward Internet group buying" are accepted. Our results provide not only academic contribution by suggestion of a research framework but also practical insight by discussion of diverse features in Internet group buying.verse features in Internet group buying.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권7호
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• pp.2972-2991
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• 2016

WLAN is the best choice in the place where complex network is hard to set up. Intelligent terminals are more and more assembled in some areas now. However, according to IEEE 802.11n/802.11ac, the access-point (AP) can only serve one user at a single frequency channel. The spectrum efficiency urgently needs to be improved. In theory, AP with multi-antenna can serve multiple users if these users do not interfere with each other. In this paper, we propose a user clustering scheme that could achieve multi-user selection through the mutual cooperation among users. We focus on two points, one is to achieve multi-user communication with multiple antennas technique at a single frequency channel, and the other one is to use a way of distributed users' collaboration to determine the multi-user selection for user clustering. Firstly, we use the CSMA/CA protocol to select the first user, and then we set this user as a source node using users' cooperation to search other proper users. With the help of the users' broadcast cooperation, we can search and select other appropriate user (while the number of access users is limited by the number of antennas in AP) to access AP with the first user simultaneously. In the network node searching, we propose a maximum degree energy routing searching algorithm, which uses the shortest time and traverses as many users as possible. We carried out the necessary analysis and simulation to prove the feasibility of the scheme. We hope this work may provide a new idea for the solution of the multiple access problem.

• 인터넷정보학회논문지
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• 제18권6호
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• pp.101-112
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• 2017

본 연구는 혁신확산이론과 혁신저항모델을 적용하여 소셜TV 혁신저항과 이용의도에 영향을 미치는 요인을 탐색하였다. 주요 결과를 중심으로 살펴보면, 첫째, 소셜TV 비이용자의 지각된 혁신특성 중 적합성과 복잡성은 혁신저항에 통계적으로 유의한 영향을 미치는 것으로 나타났다. 둘째, 소셜TV 비이용자의 인지된 위험은 혁신저항에 통계적으로 유의한 정적 영향을 미치는 것으로 나타났다. 셋째, 소셜TV 비이용자의 지각된 혁신특성 중 적합성과 복잡성은 이용의도에 통계적으로 유의한 영향을 미치는 것으로 나타났다. 넷째, 소셜TV 비이용자의 인지된 위험은 소셜TV 이용의도에 통계적으로 유의한 영향을 미치지 못한 것으로 나타났다.

• 통상정보연구
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• 제17권1호
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• pp.3-28
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• 2015

이용자의 집중을 이끌기 위한 웹광고의 자극들이 증가하는 가운데, 웹광고들이 오히려 이용자의 웹활동을 방해하는 경우가 많아졌다. 하지만 이용자들이 웹광고를 회피할수록 기업은 더욱 자극적인 광고로 이용자의 집중을 이끌고자 노력하고 있어 과연 기업이 원하는 웹광고 성과를 달성할 수 있을지에 대한 의문이 가중되고 있다. 이에 본 연구는 웹광고의 자극요소들이 웹광고에 대한 이용자의 태도와 이후 웹광고 성과에 이르는 과정을 살펴보았다. 연구결과, 웹광고의 과도한 자극이 오히려 웹광고와 해당 웹사이트에 대한 부정적인 성과를 초래할 수 있으며, 웹광고의 유용성 및 유희성에 의해 웹광고의 설득수준이 높아짐을 확인할 수 있었다. 또한, 웹사이트의 특성에 따라 인터넷신문 사이트와 전자상거래 사이트에서의 웹광고 자극과 그에 대한 성과의 차이를 비교 분석하였다. 그 결과, 전자상거래 사이트보다도 인터넷신문 사이트에서의 광고 자극이 더욱 침입성과 혼란성이 높아 웹사이트를 회피하게 됨을 확인할 수 있었다. 이러한 연구결과를 바탕으로 본 연구는 기업이 기대하는 성과를 얻을 수 있고 이용자의 편익도 증진할 수 있는 바람직한 웹마케팅의 방향을 논의하고자 한다.

• 한국컴퓨터그래픽스학회논문지
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• 제14권4호
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• pp.35-39
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• 2008

협업 시스템은 원거리의 다수 사용자들이 시간과 공간의 제약을 받지 않고 공동의 작업을 진행 할 수 있도록 서비스를 제공하는 시스템이다. 하지만 모든 시스템들이 그렇듯이 처음 사용할 때는 여러 가지 시행작오가 생기게 된다. 가상분자모델링 시스템인 VRMMS[1]는 여러 사용자들이 온라인상에서 분자 구조를 관찰하고 시뮬레이션 결과를 확인 할 수 있고 또한 피드백까지 줄 수 있는 협업시스템인데, 분자 모델을 연구하는 사람들에게는 유용한 시스템이지만 익숙하게 분자 구조를 조작하기 위해서는 인터페이스에 대한 학습이 필요하다. 가장 좋은 방법은 직접 만나서 교육을 시켜주는 것이지만 한 장소가 아닌 여러 장소에서 원격으로 실험을 진행하는 상황에서는 사용법에 대한 직접적인 교육이 힘들기 때문에 시행착오 기간이 길어질 수 있다. 본 논문에서는 이러한 시행착오를 줄이기 위해 가상의 현실세계인 세컨드라이프[2]를 통해 분자 구조를 관찰하고 시뮬레이션을 할 수 있는 협업시스템을 제안한다. 각각의 사용자들은 가상세계에서 자신의 아바타를 통해 가상분자모델링 시스템인 VRMMS를 사용하여 현실 세계에서와 같은 방식으로 실험을 진행할 수 있으며, 실험에 익숙하지 않는 사용자들은 실험방법을 직접 보고 따라 해 볼 수 있어서 좋은 학습효과를 기대할 수 있다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제5권7호
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• pp.1329-1345
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• 2011

After the 9.11 terror attack, lawful Interception (LI) has emerged as an important tool for anti-terrorist activity. Law enforcement agents and administrative government bodies effectively monitor suspicious target users of permanent IP-based network devices by LI in Packet Data Networks (PDNs). However, it is difficult to perform LI in monitoring migrating users from a location to another, who change their IPs due to the proliferation of portable Internet devices enabling 3G IP Multimedia Subsystems (IMS). The existing, manual handover technique in 3G IMS makes it even more difficult to continue the LI activities due to time-lag reissuance of LI authority warrants when the target users move to a new LI jurisdiction via a roaming service. Our proposed model is a seamless LI handover mechanism in 3G IMS to support mobility detection of the target users. The LI warrants are transferred to the new LI agent automatically with the target users when they move to a new LI jurisdiction. Thus, time-lag human intervention of reissuance of the LI warrants is removed and enables the LI authorities to continue monitoring. In the simulation of our proposed mechanism, the quality of lawful interception achieves a mean score of over 97.5% out of the possible 100% maximum score, whereas the quality of the existing mechanism has a mean score of 22.725%.

• 대한산업공학회지
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• 제39권2호
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• pp.119-128
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• 2013

Most internet users utilize internet portal search engines, such as Naver, Daum and Google nowadays. But since the results of internet portal search engines are based on universal criteria (e.g. search frequency by region or country), they do not consider personal interests. Namely, current search engines do not provide exact search results for homonym or polysemy because they try to serve universal users. In order to solve this problem, this research determines keyword importance and weight value for each individual search characteristics by collecting and analyzing customized keyword at external database. The customized keyword weight values are integrated with search engine results (e.g. PageRank), and the search ranks are rearranged. Using 50 web pages of Goolge search results for experiment and 6 web pages for customized keyword collection, the new customized search results are proved to be 90% match. Our personalization approach is not the way that users enter preference directly, but the way that system automatically collects and analyzes personal information and then reflects them for customized search results.