• Proceedings of the Korea Information Processing Society Conference
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• 2009.04a
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• pp.1247-1249
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• 2009

최근 첨단 IT 분야 기반 기술들의 상용화가 시작되고 있다. 이들 기술들을 바탕으로 이동 단말에서 다양한 서비스를 즐길 수 있는 시대로 진입하고 있다. 이동 중인 사용자는 핸드오프가 빈번히 발생되는 환경에서 스트리밍 서비스를 받게 된다. 이러한 환경에서 스트리밍 미디어의 QoS를 만족시키기 위해서는 이동성이 고려된 미디어 데이터선인출이 사용되어야 한다. 본 논문에서는 미디어 서버에서 사용자 단말로 스트리밍 미디어가 서비스 될 때 빈번한 핸드오프에 의한 기지국(Base Station : BS) 스트리밍 서버의 자원낭비를 연구한다. 논문에서는 BS의 버퍼용량을 속도와 이동거리에 따라 변화하는 량을 조사하여 선인출 용량 변화가 버퍼 사용률에 영향을 미침을 지적한다.

• Proceedings of the Korea Information Processing Society Conference
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• 2009.04a
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• pp.889-892
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• 2009

최근 자동차 에어백 장치와 노트북 하드디스크에 사용되던 가속도센서가 크기가 작아지고 가격이 내려가면서 휴대폰 디지털 카메라, PMP, 네비게이션, 등 모바일 단말기 쪽으로 적용대상을 넓혀가고 있다. 휴대폰에 적용된 가속도센서는 주로 화면 자동회전, 셔터 손떨림 방지, 게임 등의 응용개발에 활용되고 있다. 본 논문에서는 휴대형 통신기기에 필수적으로 장착되는 베이스밴드 프로세서를 이용하여 보다 정밀하고 전력 소모 또한 줄일 수 있는 건강, 의료 응용에 사용이 가능한 기술을 제시 한다.

• Proceedings of the Korea Information Processing Society Conference
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• 2022.11a
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• pp.1031-1033
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• 2022

본 논문에서는 모든 사람들이 더 안전하고 편리하게 대중 교통을 이용하기 위해 탑승할 버스를 미리 예약할 수 있는 예약 버튼 시스템과, 단말기에 카드를 찍지 않아도 탑승 버튼을 통해 요금을 자동 결제하는 시스템, 그리고 버스 내에서 직접 stop 버튼을 누르지 않아도 앱의 하차 버튼을 누르면 자동으로 벨이 울리는 어플리케이션 시스템을 제안했다. 기존 버스 관련 앱 대부분이 버스 도착 예정시간, 경로, 정류소 정보들만 있다. 본 논문에서는 여기서 더 나아가 탑승할 버스 예약, 요금 결제, 하차벨 기능을 더한 어플리케이션 기술을 제안했다.

• Proceedings of the Korea Information Processing Society Conference
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• 2008.11a
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• pp.1254-1257
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• 2008

새로운 웹 정보를 얻기 위해 웹 사이트에 빈번히 방문하는 것은 시간 낭비이며 비효율적이다. 이러한 문제를 해결하기 위해 사용자가 웹 사이트의 정보를 인터넷으로 정기 구독하는 웹 신디케이션 기술이 최근에 도입되었다. 이를 통해 사용자는 웹 사이트에 대한 낭비적인 네비게이션을 하지 않고도 비교적 빠른 시간 내에 최신 정보를 획득할 수 있다. 그러나 현재 웹 신디케이션 기술은 주로 PC 환경에서 구현 활용되고 있기 때문에 이동성에 대한 고려가 되어 있지 않다. 본 논문에서는 웹 신디케이션 기술을 모바일 단말기와 모바일 인터넷으로 확장하는 시스템을 제안한다.

• Journal of the Korea Society of Computer and Information
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• v.17 no.8
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• pp.41-50
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• 2012

Most of the developed countries and Korea have continued to invest much money in developing low-carbon vehicles such as electric car, methanol car and hydrogen car to replace the conventional fossil fuel vehicles. Government and local governments of each country, however, grope to construct roads for bicycle and public bicycle rental systems because bicycle is the only ultimate and feasible non-pollution transportation. Most of the current bicycle monitoring systems have achieved automation of rental process in bicycle stations, but they can not monitor bicycles in use. This paper develops GPS-CDMA modem combined terminals and implements a LBS-based bicycle monitoring system using them for public bicycle rental system. The monitoring system collects location information from GPS-CDMA modem combined terminals attached on bicycles and presents the moving tracks of bicycles on a GIS map for easy return and redistribution of bicycles. Also, the system helps to prevent from theft and vandalism of bicycles and to recommend the nearest bicycle station.

• Journal of the Korea Society of Computer and Information
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• v.15 no.11
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• pp.125-133
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• 2010

A policy based resource management framework is proposed, that supports the optimal QoS by applying resources management function which is changed according to the status of mobile terminal and heterogeneous connections to hand-over process of mobile terminals based on heterogeneous network. To assess the performance of policy based resource management framework proposed in this thesis, in case of applying weighted policy for selecting optimal cell in hand-over occurring among duplicated heterogeneous connections, the transmission delay was remarkably enhanced as the number of multimedia sessions increased. This means, in case of QoS deterioration of multimedia session occurring in service connection, hand-over was executed with the optimal connection.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.9
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• pp.1748-1758
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• 1994

Recently, the demand of mobile communication is rapidly increasing. Also, not only the voice service but also the nonvoice services such as data, FAX, and image service are required. Therefore, in this paper, the voice/data intergraed service methods that will be utilized as a basic core technology of the PCS systems are proposed and their performances are analyzed and compared by computer simulation. According to the simulation results, it could be seen that the performance of voice/data integrated PR-CDMA method is better than that of voice/data integrated broadband CDMA method using a dedicated terminal or a voice/data integrated terminal. The reason is that the voice/data integrated PR-CDMA method can overcome the weak points of CDMA protocol, such as a limitation of the fixed CDMA logical channel number and a falling-off in channel utilization, by using PRMA protocol as a multiple access method that the terminals to which a CDMA logical channel is assigned compete.

• Journal of the Korea Society of Computer and Information
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• v.11 no.1 s.39
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• pp.251-258
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• 2006

When producing a wireless web contents by using wire web contents for PC environment, we should consider how to represent lots of information being suitable with PC environment to wireless devices having narrow performance. Therefore, we propose mobile page editor for manager to select and modify specific contents with the existing wire web page. Also, we try to define an intermediate language based on DID(Digital Item Declaration) of MPEG-21 multimedia framework which defines source of converting information and wireless web contents generating at mobile editor in considering real time service problem when transcoding multimedia information in a web server into wireless device having low resolution, narrow performance of media process, memory, and so on.

• Journal of the Korea Society of Computer and Information
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• v.15 no.6
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• pp.65-72
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• 2010

In ad-hoc network, the technique to efficiently consume the limited amounts of energy is an important issue since the wireless terminal node is operated on batteries as their energy resource. In order to extend the system lifetime, through a balanced energy consumption, we must delay the situation in which a particular terminal node's energy is depleted and results in system disconnection. Also, the link, which has low reliability due to the mobility of the node, should be avoided considering the key element when setting up the route. The proposed CMLR method in this paper enables to increase the efficiency of energy consumption with a new cost function considering the residue energy of node, error rate of link, and transmission energy consumption. This method is extending the network lifetime and increasing the energy efficiency by compromising the value between the minimization of the transmission energy consumption and maximization of the node's lifetime. Through the simulations the proposed CMLR algorithm was verified by showing better performance over the conventional methods in terms of network lifetime and path efficiency.

• Journal of the Korea Society of Computer and Information
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• v.25 no.2
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• pp.113-122
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• 2020

In this paper, we propose the terminal authentication system using blockchain and TOTP(Time-based One-time Password Algorithm) to sustain a continuous authentication between user device and service device. And we experiment this system by using door-lock as a terminal of IoT(Internet of Things). In the future, we can apply this result to several devices of IoT for convenience and security. Although IoT devices frequently used everyday require convenience and security at the same time, it is difficult for IoT devices having features of the low-capacity and light-weight to apply the existing authentication technology requiring a high amount of computation. Blockchain technology having security and integrity have been used as a storage platform, but its authentication cannot be performed when the terminal cannot access any network. We show the method to solve this problem using Blockchain and TOPT.