• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2018.10a
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• pp.457-460
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• 2018

The mobile communication based train control is the train control system by utilizing wireless communication rather than conventional wired communication. Traditional train control operates train occupation, safety integrity and moving authority using fixed block wired railway signal system. Since introduction of mobile communication in railway area, railway operators can provide improved passager services. Futhermore, it can replace inefficient train onboard equipments and railway ground facilities for economic benefits. In this paper we introduce mobile communication based railway system currently in operation around the world. Moreover, we provide the minimum requirements of the radio communication performance. Proposed minimum requirements of the radio communication improve more secure and efficient mobile communication based train control system.

• The Transactions of the Korea Information Processing Society
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• v.6 no.11
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• pp.2845-2862
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• 1999

As the technical advances in portable computers and wireless communication technologies, mobile computing environment has been rapidly expanded. The mobile users on mobile host can access information via wireless communication from the distributed heterogeneous multidatabase system in which pre-existing independent local information systems are integrated into one logical system to support mobile applications. Hence, mobile transaction model should include not only the features for heterogeneous multidatabase systems but also the ones for mobile computing environment. In this paper, we proposed a mobile flex transaction model which extends the flexible transaction model that previously proposed for heterogeneous multidatabase systems is extended to support the requirements of mobile heterogeneous multidatabase systems. We also presented the execution control mechanism of the mobile flex transaction model. The proposed mobile flex transaction model allows the definition of location-dependent subtransactions, the effective support of hand-over, and the flexibility of transaction executions. Hence, the proposed mobile flex transaction model can be suit to mobile heterogeneous multidatabase systems that have low power capability, low bandwidth, and high communication failure possibility.

• Proceedings of the Korea Society of Information Technology Applications Conference
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• 2005.11a
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• pp.7-12
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• 2005

In this paper, we implemented an e-mail and chat program (client) for communication between mobile devices and PCs based on WIPI a South Korea's open wireless platform form developing device and content independent software to break from the way of developing contents that is dependent on different wireless platforms to each mobile communications company. While traditional e-mail and chat programs are written for PC-to-PC communication, we develop them for mobile-to-PC and mobile-to-mobile communications, and we expect to see various mobile contents in the future.

• Information Systems Review
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• v.12 no.1
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• pp.145-164
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• 2010

Since the third generation (3G) mobile communication service has been launched by most mobile communication operators in Korea, the portion of data service in mobile communication service becomes one of the most important factors in mobile communication service market. In past mobile communication market, most mobile communication operators made their profit mostly from voice communication service. However, the portion of profit from data service has gradually increased based on both video phone call and mobile Internet service. In this situation, LG telecom launched the full browsing mobile Internet service. This service provides a new type of mobile Internet service platform which enables to access the World Wide Web using mobile browsers, so we generally access the Web using web browsers in the desktop computer. Under the open network structure of mobile Internet like situation, it is very important to analyze the factors which can affect the competition between mobile communication service companies. So, in this paper, we first present the current state of full browsing service, followed by the expectation of its growth potentials and barriers. Then, we analyze the advantages and disadvantage of LG telecom as a first-mover and SK telecom/KTF as followers. Finally, based on this analysis, we predict the future competition among these companies and the market.

• Proceedings of the Korea Society of Information Technology Applications Conference
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• 2005.11a
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• pp.277-280
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• 2005

With the proliferation of mobile terminals, use of the Internet in mobile environments is becoming more common. To support mobility in these terminals, Mobile IPv4 is proposed and represents the standard in IPv4 environments. Authentication should be mandatory, because mobile terminals can utilize Internet services in any foreign domain. Mobile IPv4 provides symmetric key based authentication using the default HMAC-MD5. However, symmetric key based authentication creates a key distribution problem. To solve this problem, public key based authentication mechanisms have been proposed. In this paper, the performance of each of these mechanisms is evaluated. The results present that, among these mechanisms, partial certificate based authentication has superior performance, and certificate based authentication has the worst performance. Although current public key based authentication mechanisms have lower performance than symmetric key based authentication, this paper presents the possibility that public key based authentication mechanisms may be used for future mobile terminal authentication.

• Journal of information and communication convergence engineering
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• v.14 no.2
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• pp.89-96
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• 2016

In mobile communication, there are various types of handoff for the support of all forms of mobility. Proxy mobile IPv6 (PMIPv6) enables local network-based mobility management of a mobile node without any effect of mobility-related signaling. Recently, PMIPv6 has been considered for supporting mobility management in LTE/SAE-based mobile networks. To support seamless mobility in heterogeneous mobile networks, the overall cost of handoffs needs to be minimized and the procedure should be guaranteed to be secure. However, the reduction of the authentication cost has not been fully investigated to provide seamless connectivity when mobile users perform a handoff between the PMIPv6 domains. This paper proposes secure pre-authentication schemes, completing an authentication procedure before performing a handoff, for a fast handoff in PMIPv6. Analytic models have been used for measuring the authentication latency and for the overhead cost analysis. In addition to providing fast authentication, the proposed pre-authentication schemes can prevent threats such as replay attacks and key exposure.

• International Journal of Contents
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• v.9 no.1
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• pp.11-17
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• 2013

Recently, online real-time web accessible mobile devices such as smartphones, tablet PCs and application services have been developing rapidly. Hospitals also need to adopt an efficient information system that can provide decent medical services under mobile computing environments to complete future medical services. This study proposes a system in which a doctor can examine a patient and make out a prescription in a ward on a real-time based on the current Order Communication Systems (OCSs) through mobile interfaces. The proposed system implements mobile web pages using HTML5, instead of a mobile app. Web processing speed can be enhanced using the web socket and web storage functions of HTML5.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.22 no.11
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• pp.1511-1517
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• 2018

Mobile Device-to-Device (D2D) caching networks can transmit multimedia data to users directly without passing through any network infrastructure by storing popular multimedia contents in advance that are popular among many mobile users at caching server devices (CSDs) in distributed manners. Thus, mobile D2D caching networks can significantly reduce backhaul traffic in wired networks and service latency time of mobile users. In this paper, we propose an efficient transmission scheme that can enhance the transmission efficiency of mobile D2D caching networks by using multiple CSDs that are caching the contents that are popular among mobile users. By sorting the multiple CSDs that are caching a content that mobile users want to receive according to their channel gains, the proposed scheme can reduce the complexity of algorithm significantly, compared to an optimal scheme based on Brute-force searching, and can also obtain much higher network transmission efficiency than the existing Blanket and Opportunistic transmission schemes.

• International Journal of Internet, Broadcasting and Communication
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• v.11 no.3
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• pp.8-19
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• 2019

Since their emergence in 2007, smart phones have advanced up to the point that 5G mobile communication in 2019 started to be commercialized. Accordingly, now it is possible to share 3D modeling files and collaborate by means of a mobile web. As the recently commercialized 5G mobile communication network is so useful in sharing 3D modeling files and collaborating that even large-size geometry files can be transmitted at ultra high speed with ultra low transfer delay. We examines characteristics of major 3D file formats such as STL, OBJ, FBX, and glTF and compares the existing 4G LTE (Long Term Evolution) network with the 5G NR (New Radio) mobile communication network. The loading time and packets of each format were measured depending on the mobile web browser environments. We shows that in comparison with 4G LTE, the loading time of STL and OBJ file formats were reduced as much as 6.55 sec and 9.41 sec, respectively in the 5G NR and Chrome browsers. The glTF file format showed the most efficient performance in all of the 4G/5G mobile communication networks, Chrome, and Edge browsers. In the case of STL and OBJ, the traffic was relatively excessive in 5G NR and Edge browsers. The findings of this study are expected to be utilized to develop a 3D file format that reduces the loading time in a mobile web environment.

• 한국HCI학회:학술대회논문집
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• 2008.02b
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• pp.239-244
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• 2008

We lead a life in our community, beginning a new relationship with a stranger or maintaining or stopping existing relationships. Relationships with others are sustained through social activities based on communication. Generally speaking, by exchanging feelings and information through communication, relationships are formed and continued, and strengthened through active communication As a result of the development of technologies and information technology over the recent 10 years, a mobile phone has stood as a communication channel, and now it has become such a universal, and highly intimate and important means of communication that almost all the Koreans use more often than wired phones. Today, people have their communication channel available for others, by using a mobile phone at any time and anywhere. Like this, mobile phones have been playing a key role in helping people maintain, repair and strengthen their personal relationship, but from the perspective of personal relationship management, they still remain as an aid to help communication, failing to provide a positive help for actual relationship management. This study was designed to provide services supporting user's personal relationship management, focusing on the use of mobile phones as a major tool of communication, aiming to enable users to understand current state of their relationship and make relationship management efforts, or communication behaviors, by informing who needs communication, on the basis of data on mobile phone calls. To this end, the study established a method to extract intimacy between users and callers and develop a prototype of services supporting personal relationship management, using relationship characteristics in terms of mobile communication.