• IEMEK Journal of Embedded Systems and Applications
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• v.4 no.3
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• pp.126-133
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• 2009

There are already many researches providing u-Healthcare service, but they have left problems to be improved. First of all, the transmission range between sensor nodes and the gateway are restricted. Hence, patients feel uncomfortable because of they need to possess or locate closed to a gateway all the time when they aggregates their medical data. Also, the existing systems have not considered life environment that is important to analyze patient's diseases. Moreover, a guardian need to located close to patient or possess a mobile device that monitors a patients' status in real time when they are in outdoor. In this research, we present multi-hop packet transfer algorithm and compilation of life environment which help improve the problem of the existing researches. Likewise, we designed and implemented a medical information database and a real-time web monitoring system that manage patients' personal history and monitor a patients' status in real time. In this paper, we design and implement the u-Healthcare system based on mobile environment and we present a result when we tested our u-Healthcare system in scenario environment.

• Proceedings of the Korea Information Processing Society Conference
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• 2001.04a
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• pp.81-84
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• 2001

PC 환경이 아닌 무선 인터넷 환경에서 제공되는 Mobile GIS(Geographic Information System)는 시간과 공간의 제약을 극복하고 실시간으로 지리정보를 얻을 수 있는 장점을 가지고 있으나, 사용자의 무선단말기와 서버 사이에 접속이 유지되어 있어야만 무선으로 GIS 서비스를 이용할 수 있다. 이는 현재 국내 무선 네트워크의 느린 속도와 비싼 이용 요금을 감안하면 Mobile GIS 가 대중화되는데 장애요인이 되고있다. 그리고 무선 인터넷 서비스가 급격히 증가하면서 Mobile GIS는 보안상 약점을 드러낼 것으로 예측된다. 그러므로 본 논문에서는 공개된 불특정다수의 무선 네트워크 환경에서 발생할 수 있는 보안의 피해와 그에 따른 기본적 Mobile Security 서비스에 대해 알아보고, 정보보호 입장에서 Mobile Database 를 연구하였다. 또한 Mobile GIS 를 위한 WAP 게이트웨이에서 공간데이터의 유출 가능성을 발견하였고, 이를 위한 해결책으로 J2ME 의 Pre-verification 기능과 종단간 암호화 (End-to-End Security) 기능을 Mobile GIS 설계에 적용하여 무선 환경에서 동적인 지도서비스와 더불어 공간 데이터의 보안을 유지할 수 있는 기법을 제시하였다. 이 연구를 통해 대역폭(Bandwidth)의 한계를 지닌 개방적 무선환경에서 Mobile GIS와 같은 컨텐츠 프라이버시(Contents Privacy) 보호가 요구되는 분야에 응용될 수 있으리라 기대된다.

• KIISE Transactions on Computing Practices
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• v.24 no.1
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• pp.1-9
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• 2018

Low-power long-range networks (LoRa) has a comprehensive coverage of up to 30 km, so that long-range positioning is possible. However, the position error in the current LoRa environment is over 500 m. This makes it difficult to use practical location services in the LoRa environment. In this paper, we propose a method to improve the position accuracy by correcting an inaccurate visual error when sending a signal from a mobile node to a gateway through the reference node of each zone in the LoRa environment. Experiments were carried out using MATLAB, and a radio propagation algorithm, the Hata model, was used to cancel out the stationary noise and to evaluate the environmental noise. Experimental results showed that the error range decreased as the number of reference nodes increased and a mobile node approach the reference node.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38B no.1
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• pp.34-45
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• 2013

Due to its self-configuring nature, the tactical mobile ad hoc network is used for communications between tactical units and the command and control center (CCC) in battlefields, where communication infrastructure is not available. However, when a tactical unit moves far away from the CCC or there are geographical constraints, the data link between two communicating nodes can be broken, which results in an invalid data route from the tactical units to CCC. In order to address this problem, in this paper we propose a hierarchical connectivity maintenance scheme, namely ADLCoM (Autonomous Data Link Connectivity Maintenance). In ADLCoM, each tactical unit has one or more GW (gateway), which checks the status of data links between tactical units. If there is a possibility of link breakage, GWs request ground or aerial unmanned vehicles to become a relay for the data link. The simulation results, based on tactical scenarios, show that the proposed scheme can significantly improve the network performance with respect to data delivery ratio.

• Journal of Digital Contents Society
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• v.10 no.1
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• pp.87-96
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• 2009

Digital Broadcast Service is being very popular and the delivery mechanism for digital broadcast content through IP network has progressed constantly, due to the advance of video and audio compression and network technologies. From these trends, in Korea, the commercial IPTV service starts in this year after the law related to IPTV is enacted last year. Since IPTV service, which integrates broadcast and communication services, can give an infrastructure for fusion of communication and interactive multimedia data service, IPTV service is attractive. Recently, by the advent of various wireless connection technologies and the mobile devices of high capability, Mobile IPTV, which has an advantage of not only IPTV but also mobile TV, has gained much interest. In this paper, we review a necessary ingredient for Mobile IPTV in the next generation wired/wireless convergence network environment which consists of heterogeneous wireless access networks. In addition, we propose the scheme for user mobility and service session mobility management using RTSP protocol and introduce the service gateway concept to guarantee the extension of IPTV service platform.

• Journal of KIISE
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• v.43 no.6
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• pp.710-717
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• 2016

Recently, several research studies on things abstraction framework have been proposed in order to implement the multi-service Internet of Things (IoT) system, where various IoT services share the thing devices. Distributed things abstraction has an IoT service duplication problem, which aggravates power consumption of mobile devices and network traffic. On the other hand, cloud server-centric things abstraction cannot cover real-time interactions due to long network delay. Fog server-centric things abstraction has limits in insufficient IoT interfaces. In this paper, we propose Smart Fog which is a fog server-centric things abstraction framework to resolve the problems of the existing things abstraction frameworks. Smart Fog consists of software modules to operate the Smart Gateway and three interfaces. Smart Fog is implemented based on IoTivity framework and OIC standard. We construct a smart home prototype on an embedded board Odroid-XU3 using Smart Fog. We evaluate the network performance and energy efficiency of Smart Fog. The experimental results indicate that the Smart Fog shows short network latency, which can perform real-time interaction. The results also show that the proposed framework has reduction in the network traffic of 74% and power consumption of 21% in mobile device, compared to distributed things abstraction.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.4
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• pp.752-757
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• 2016

Machine to Machine (M2M) communications is communications between a business application and devices via a communication network without any direct human interaction. The aim of our research is to connect any M2M device with an M2M AS (Application server) through an IMS (IP Multimedia Subsystem) Network Core using a M2M Gateway, in order to develop an M2M Horizontal Services Platform over IMS. An IP Multimedia Subsystem (IMS) is an architectural framework defined by the wireless standards body of the 3rd Generation Partnership Project (3GPP) for delivering IP multimedia services to mobile users. This paper shows the design and implementation of a Horizontal M2M Network Services Platform over an IP Multimedia Subsystem (IMS) using the Message Session Relay Protocol (MSRP). We summarize the protocols and architectures that formed the basis for the creation of our architecture. We provide a detailed description of our architecture design, describing the call flow of the proposed architecture and the entities operating in each process. We also describe the design and implementation process detailing the different tools used, explaining the selection of each component and its importance; also how we designed and implemented the M2M gateway, M2M Application Server, Open IMS Core, business application and M2M devices.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.44 no.2 s.314
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• pp.47-59
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• 2007

Recently, Healthcare system has not been standardized and has been developed as an embedded system lacking interoperability. We are finally going to face such problems as having excessive load in using network caused by the uncontrolled spread of system and un-guaranteed interoperability among the heterogeneous systems. We suggest the possibility that OSGi and JADE can be accepted as a solution for the above problems.

• Journal of the Korea Society of Computer and Information
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• v.12 no.1 s.45
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• pp.33-42
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• 2007

Mobile ad-hoc network(MANET) can increase independence and flexibility of network because it consists of mobile node without the aid of fixed infrastructure. But, Because of unrestriction for the participation and breakaway of node, it has the difficulty in management and stability which is a basic function of network operation. Therefore, to solve those problems, we suggest a distributed weighted clustering algorithm from a manageable and stable point of view. The suggested algorithm uses distributed weighted clustering algorithm when it initially forms the cluster and uses a concept which is distributed gateway and sub-cluster head to reduce the re-clustering to the minimum which occurs mobile nodes after forming the cluster. For performance evaluation, We compare DCA and WCA with the suggested algorithm on the basis of initial overhead, resubscriber rate and a number of cluster.

• Journal of Digital Convergence
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• v.12 no.8
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• pp.265-270
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• 2014

This study in coping with the current trend is to propose the environment for training 3-Tier App development being focused on the system to develop mobile applications where its related developers are scarce. Design and implementation of training system for the development of 3-Tier App in this paper is to realize the environment for software development for colleges as same as that in IT companies. For 3-Tier App development training system, 3 students with 3 computers work as a group. The above-mentioned 3 computers include a computer for development, Gateway server, and DB server together with legacy system. Also, each of the 3 students shall be given roles of the foregoing sections. We have educated 3-Tier App training system as a practical class for 64 students in junior students of computer information major. Through training session, it was confirmed that we can foster the students as custom-made talents who understand company's development environment. Also, the Comparison of 3-Tier and Stand-alone App Development Training System for 10 distinct description, we know that 3-Tier app development training system was very superior to stand-alone app development training system in the educational effects.