• 산업기술연구
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• 제26권B호
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• pp.199-206
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• 2006

Internet telephony provides voice communication services with added flexibility for multimedia extension at a lower cost compared to traditional telephone systems. We implemented an internet telephony system as an overlay network without a centralized server, using a distributed hash table (DHT). Compared to the current server-based internet telephony system, our system is fault-tolerant, scalable, and can be flexible extended to various services and advanced to integrated service. To demonstrate the high flexibility of our DHT-based internet telephony system, we made our system cooperate with web servers. Web users can check up others' online stales and establish voice communication sessions to online users at a mouse click. This technology can be applied to more complex services such as multimedia messaging or video conference service.

• 한국콘텐츠학회논문지
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• 제5권5호
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• pp.228-237
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• 2005

본 논문은 호텔의 웹사이트에 대한 인터넷 사용자들의 평가는 호텔의 등급, 규모, 소유권, 그리고 고객의 유형에 따라서 다를 것이라는 가설을 갖고 연구하였다. 연구 결과에 따르면 호텔의 위치와 고객의 유형은 인터넷을 이용한 마케팅에서는 전략적 이점이 점차적으로 약해지고 있으나 호텔의 등급, 규모, 그리고 소유권 구조는 인터넷을 이용한 비즈니스 환경에서도 우위를 점하는 것으로 나타났다. 또한 연구를 통하여 알 수 있었던 것은 인터넷으로 하여 도심지 호텔과 지방호텔 간의 차이가 점점 좁혀지고 있으므로 지방 호텔의 마케팅의 기회가 확대될 가능성이 있다는 것이다.

• Journal of Information Technology Applications and Management
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• 제16권4호
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• pp.93-107
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• 2009

This study investigated consumer preferences for Internet medical information service in China using the multi-attribute utility theory. The multi-attribute utility theory is a compositional approach for modeling consumer preferences wherein researchers calculate the overall service utility by summing up the evaluation results for each attribute. We found that Chinese Internet medical information users consider the availability of information and quick response to be the most important attributes. Further, they think that the comment feature is less important as compared to other attributes such as costs and updates. In addition, we found that the Internet users having more Internet experience consider these attributes to be more important as compared to the people who are just beginning to surf the Internet. For any successful Internet business, Internet marketers should assess individual-level preference and accordingly organize a fresh campaign. As of now, Internet marketers need estimation methods to predict the market performance of new services in many different business environments. We believe that the multi-attribute utility theory is a useful approach in this regard.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제9권6호
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• pp.1996-2013
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• 2015

This paper considers a scenario that more D2D users exist in the cell, they compete for cellular resources to increase their own data rates, which may cause transmission interference to cellular users (CU) and the unfairness of resource allocation. We design a resource allocation scheme for selfish D2D users assisted by cooperative relay technique which is used to further enhance the users' transmission rates, meanwhile guarantee the QoS requirement of the CUs. Two transmission modes are considered for D2D users: direct transmission mode and cooperative relay transmission mode, both of which reuses the cellular uplink frequency resources. To ensure the fairness of resource distribution, Nash bargaining theory is used to determine the transmission mode and solve the bandwidth allocation problem for D2D users choosing cooperative relay transmission mode, and coalition formation game theory is used to solve the uplink frequency sharing problem between D2D users and CUs through a new defined "Selfish order". Through theoretical analysis, we obtain the closed Nash bargaining solution under CUs' rate constraints, and prove the stability of the formatted coalition. Simulation results show that the proposed resource allocation approach achieves better performance on resource allocation fairness, with only little sacrifice on the system sum rates.

• International Journal of Internet, Broadcasting and Communication
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• 제10권3호
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• pp.115-120
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• 2018

Current medical tourism is focused on the services of large hospitals and it is hard to find ways to attract the users. Users collect information for medical tourism through various paths in order to receive the medical consultations and customized tour services. To expand medical tourism to small and medium sized hospitals, it is necessary to have the customized medical consultations, tours and interpreter services, which are the key elements of medical tourism. This study suggests ways to provide the services based on information on medical consultations, tours and interpreter services that users had experienced directly, and also based on the platform for the essential items integrated from users, hospitals and guides' viewpoints. With information on hospitals that provide medical consultations and guides who are able to provide professional services in translation, interpretation and customized tour, users may accumulate and share the information about hospitals and customized tours verified by other users from the integrated platform. To match the contents provided by hospitals and guides with information experienced by users into a system, this study suggests the construction plan for the service model that can match the experience information between users and hospitals, between users and guides and between hospitals and guides systematically by operating the data in the universal container.

• 한국전자통신학회논문지
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• 제6권5호
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• pp.731-737
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• 2011

본 연구는 인터넷 이용자들을 대상으로 개인정보 유출 가능성에 따른 심리적 불안에 대해서 논의하였다. 성별, 인터넷 이용량, 사이트 가입 수, 전자상거래 빈도에 따라 개인정보 유출 가능성에 대한 심리적 불안이 어떠한 차이를 나타내는지 알아보았다. 분석 결과 여성이 남성보다 심리적 불안이 더 크게 나타났으며, 인터넷을 많이 이용할수록 심리적 불안이 크게 나타났다. 하지만 사이트 가입 수나 한 달 평균 전자 상거래 빈도에 따른 개인정보 유출 가능성에 대한 심리적 불안에는 차이가 나타나지 않았다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제18권6호
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• pp.1462-1477
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• 2024

With the evolving complexity of connected vehicle features, the volume and diversity of data generated during driving continue to escalate. Enabling data sharing among interconnected vehicles holds promise for improving users' driving experiences and alleviating traffic congestion. Yet, the unintentional disclosure of users' private information through data sharing poses a risk, potentially compromising the interests of vehicle users and, in certain cases, endangering driving safety. Federated learning (FL) is a newly emerged distributed machine learning paradigm, which is expected to play a prominent role for privacy-preserving learning in autonomous vehicles. While FL holds significant potential to enhance the architecture of the Internet of Vehicles (IoV), the dynamic mobility of vehicles poses a considerable challenge to integrating FL with vehicular networks. In this paper, a novel clustered FL framework is proposed which is efficient for reducing communication and protecting data privacy. By assessing the similarity among feature vectors, vehicles are categorized into distinct clusters. An optimal vehicle is elected as the cluster head, which enhances the efficiency of personalized data processing and model training while reducing communication overhead. Simultaneously, the Local Differential Privacy (LDP) mechanism is incorporated during local training to safeguard vehicle privacy. The simulation results obtained from the 20newsgroups dataset and the MNIST dataset validate the effectiveness of the proposed scheme, indicating that the proposed scheme can ensure data privacy effectively while reducing communication overhead.

• 한국산학기술학회논문지
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• 제11권9호
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• pp.3458-3464
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• 2010

최근 빠른 주기로 많은 양의 새로운 정보가 생성되기 때문에, 사용자 중심의 정보 검색을 위해 RSS라는 신디케이션 기술이 제공되고 있다. RSS는 새롭게 갱신된 콘텐츠를 자동으로 전달받을 수 있어 신규 정보를 찾기 위해 사이트에 지속적으로 접근하지 않아도 된다. 본 논문에서는 블로그 정보 검색을 위해 RSS 문서의 주소를 수집하는 수집기와 사용자 질의에 따른 RSS 문서의 순위결정 방법을 제안한다. 제안하는 정보 검색 기법을 이용하면 사용자가 RSS 문서를 효과적으로 검색할 수 있다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제5권11호
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• pp.2254-2271
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• 2011

Access control in dynamic environments needs the ability to provide more access opportunities of information to users, while also ensuring protection information from malicious users. Trust and risk are essential factors and can be combined together in access control decision-making to meet the above requirement. In this paper, we propose the combination of the trust and risk in access control to balance information accessibility and protection. Access control decision is made on the basis of trustworthiness of users and risk value of permissions. We use potential relations between users and relations between permissions in access control. Our approach not only provides more access opportunities for trustworthy users in accessing permissions, but also enforces traditional access control constraints such as Chinese Wall policy and Separation of Duty (SoD) of Role-Based Access Control (RBAC) model in an effective way.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제14권3호
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• pp.1280-1300
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• 2020

In the modern financial sector, interest in providing financial services that employ blockchain technology has increased. Blockchain technology is efficient and can operate without a trusted party to store all transaction information; additionally, it provides transparency and prevents the tampering of transaction information. However, new security threats can occur because blockchain technology shares all the transaction information. Furthermore, studies have reported that the private keys of users who use the same signature value two or more times can be recovered. Because private keys of blockchain identify users, private key leaks can result in attackers stealing the ownership rights to users' property. Therefore, as more financial services use blockchain technology, actions to counteract the threat of private key recovery must be continually investigated. Private key recovery studies are presented here. Based on these studies, duplicated signatures generated by blockchain users are defined. Additionally, scenarios that generate and use duplicated signatures are applied in an actual bitcoin environment to demonstrate that actual bitcoin users' private keys can be recovered.