• Proceedings of the KIEE Conference
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• 2006.04a
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• pp.144-146
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• 2006

The Data Matrix of two-dimensional bar codes is a new technology capable of holding relatively large amounts of data compared to the conventional one-dimensional bar code which is just a key that can access detailed information to the host computer database. A secret key is used to prevent a watermark from malicious attacks. We encoded copyright information into a Data Matrix bar code for encoding process and it was spread a pseudo random pattern using owner key. We embedded a randomized watermark into the image using watermark's embedding position, pattern generated with a secret key. The experimental results have shown that the proposed scheme has good quality and is very robust to various attacks, such as JPEG compression and noise. Also the performance of the proposed scheme is verified by comparing the copyright information with the information which is extracted from a bar code scantier.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1961-1962
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• 2008

Hybrid Peer-to-Peer structure is sharing resource in each peer, but various resource that is with go peer indexing and segment that search from attained in server who function is solidified that is not attained in peer itself be. Basis algorithm was based on Ethernet protocol and administration of each peer enabled in center server and peer does as can confirm breakdown existence and nonexistence through communication with center server and the internet through this directly expensive test expense and a lot of test times of existing test method of access method necessary problem effectively improve.

• 한국정보통신설비학회:학술대회논문집
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• 2006.08a
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• pp.47-52
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• 2006

In this paper, we suggested new network architecture to provide seamless service between the cellular system and new wireless broadband network such as IEEE 802.16e, called WiBro. The interworking technologies are very important issue because mobile operator should provide service connectivity between various wireless networks based on different access technologies. Moreover a change and modification on legacy network should be minimized for providing interworking with new wireless broad-band network. We implemented proposed interworking architecture between 3G cellular network and 802.16e network to provide seamless service including interworking unit in real test environment. Also, we performed performance evaluation in hybrid network environments.

• Journal of Korea Multimedia Society
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• v.20 no.9
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• pp.1519-1526
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• 2017

The existing DSRC(Dedicated Short Range Communication) scheme has a limitation in providing various services through short-range wireless communication. Therefore, it is necessary to develop an intelligent WAVE/DSRC hybrid wireless platform that can improve data transmission speed and extend the effective communication range. This paper introduces WAVE/DSRC integrated platform technology using WAVE(Wireless Access in Vehicle Environments) to overcome the disadvantages of DSRC. First, the desinged software configuration of the WAVE/DSRC integrated platform is described. Then each task operation scheme and WAVE software design are described. By applying the WAVE/DSRC integrated platform, we can compensate the shortcomings of DSRC. It can provide more accurate and reliable services.

• Annual Conference of KIPS
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• 2005.11a
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• pp.1247-1250
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• 2005

이 논문은 multicarrier CDMA 이동 통신 시스템에서 직-병렬 혼합 pseudo-noise (PN) 코드 동기 획득 기술을 제안 했으며 다중경로 페이딩 채널에서 multiple access interference (MAI) 의 영향을 분석하였다. 직-병렬 혼합 동기 획득 방식은 입력되는 코드 위상의 불확정 영역 전체를 직렬 획득 방식과 병렬 획득 방식을 조합하여 탐색하는 방식이다. 이러한 방식은 완전 병렬획득보다 MAI의 환경에서 mean acquisition time (MAT)이 조금 늦어지지만 하드웨어의 구조를 훨씬 단순화 할 수 있다. 검파 및 오경보 확률을 closed-form 표현으로 mean acquisition time (MAT)를 유도하였다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.11
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• pp.5290-5304
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• 2016

With the growth of the massive amount of data, the failure probability of the cloud storage node is becoming more and more big. A single fault tolerance strategy, such as replication and erasure codes, has some unavoidable disadvantages, which can not meet the needs of the today's fault tolerance. Therefore, according to the file access frequency and size, an adaptive hybrid redundant fault tolerance strategy is proposed, which can dynamically change between the replication scheme and erasure codes scheme throughout the lifecycle. The experimental results show that the proposed scheme can not only save the storage space(reduced by 32% compared with replication), but also ensure the fast recovery of the node failures(increased by 42% compared with erasure codes).

• Journal of the Semiconductor & Display Technology
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• v.3 no.4
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• pp.13-17
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• 2004

As the usage of wireless LAN becomes common in working environment, the number of database systems that support both wired and wireless users increases rapidly. The characteristics of wireless LAN that its speed is slow relatively comparing to wired network and the users in its environment connects to different communication points as they moves creates another challenge to be resolved in database systems. In the environment of hybrid communication systems, wired and wireless for voluminous data amount and a number of users, the two layer architecture of the conventional client-server database systems has limitation in the system performance. This is due to that server is the only point of data service in client-server database systems. In this paper, we discuss a new extended database system architecture that data services are distributed among servers and clients based on user database access patterns in order to improve system performance. We analyze the expected system performance by using simulation technique and prove the practical utilization of the system by demonstrating experimental results.

• Annual Conference of KIPS
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• 2017.11a
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• pp.403-406
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• 2017

지오펜스와 하이브리드 비콘을 이용한 입원환자 출입관리시스템은 모바일 앱, 관리자는 웹 화면을 이용해 입원 환자들의 병원 출입을 관리하는 시스템이다. 기존의 외출 시스템은 환자가 외출 신청서를 수기로 작성하고 주치의의 허락 하에 외출하는 형태이지만, 신청서 작성 과정을 거치지 않고 무단으로 외출하는 환자의 경우 외출 시점이나 현재 위치 등을 파악하기 어려운 문제가 있다. 무단 외출 환자를 즉각적으로 파악하지 못하는 경우 해당 환자들이 음주 또는 귀원하지 않는 등의 사고의 원인이 되는 문제가 발생할 수 있다. 본 논문에서는 지오펜스와 하이브리드 비콘을 이용해 환자들의 병원 출입 유무의 정확성을 높이고 무단 외출 환자를 즉각적으로 파악하는 방안을 제시한다.

• Proceedings of the IEEK Conference
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• 2002.07c
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• pp.1367-1370
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• 2002

This paper introduces a new web based method to remotely upgrade firmwares of Cable Modems (CM) which are integral part in providing high-speed Internet access through Hybrid Fiber Coaxial (HFC) networks. Also, it discusses various practical problems arising in the upgrading process. Traditional upgrade has been performed by modifying the CM configuration fie. This paper shows a new web based CM firmware upgrade method using SNMP and MIB which greatly reduces upgrading time, cost and man-hour than traditional firmware upgrade methods. This method has been shown to be very efficient and practical. This method will make significant impact especially because tens of million cable modems are currently waiting to be upgraded soon to the next version from the current version.

• ETRI Journal
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• v.40 no.1
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• pp.61-71
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• 2018

In this study, we developed hybrid control algorithms in smart base stations (SBSs) along with devised communication, caching, and computing techniques. In the proposed scheme, SBSs are equipped with computing power and data storage to collectively offload the computation from mobile user equipment and to cache the data from clouds. To combine in a refined manner the communication, caching, and computing algorithms, game theory is adopted to characterize competitive and cooperative interactions. The main contribution of our proposed scheme is to illuminate the ultimate synergy behind a fully integrated approach, while providing excellent adaptability and flexibility to satisfy the different performance requirements. Simulation results demonstrate that the proposed approach can outperform existing schemes by approximately 5% to 15% in terms of bandwidth utilization, access delay, and system throughput.