• The KIPS Transactions:PartC
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• v.13C no.4 s.107
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• pp.455-460
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• 2006

Currently, the IETF group is working on service differentiation in the Internet. However, in wireless environments such as Ad-hoc networks, where channel conditions are variable and bandwidth is scarce, the Internet differentiated services are suboptimal without lower layers' support. The IEEE 802.11 standard for Wireless LANs is the most widely used WLAN standard today. 1t has a mode of operation that can be used to provide service differentiation, but it has been shown to perform badly. In this paper, we present a new service differentiation scheme for support QoS in the wireless IEEE 802.11, which is based on a multiple queuing system to provide priority of user's flow. We simulate and analyze the performance of our algorithm and compare its performance with the original IEEE 802.11b protocol. Simulation results show that our approach increases overall throughput in the MAC layer.

• Annual Conference of KIPS
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• 2019.05a
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• pp.204-207
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• 2019

DDoS(Distributed Denial of Service) 공격은 네트워크상에서 다수의 시스템 협업으로 하나의 표적 시스템을 공격하여 서비스의 가용성을 침해하는 공격이다. 이는 점차 지능적인 방법으로 진화하고 있으며 특히 IoT를 대상으로 한 DDoS 공격이 증가하고 있다. 이기종의 기기들이 연결된 IoT는 기존 IT디바이스와 비교하여 제한된 자원을 가지고 있어 IoT 네트워크 특성을 고려한 DDoS 보안 기법이 요구된다. 국제 인터넷 표준화 기구 IETF에서 IoT를 지원하기 위해 제정한 CoAP(Constrained Application Protocol)은 기존 IT 네트워크와 호환성을 가진 응용 계층 프로토콜이다. 본 논문은 CoAP의 DDoS 공격 취약점과 대응 방안을 정리하고 새로운 프로토콜을 추가할 시 고려해야 할 사항을 제시한다.

• Journal of Digital Contents Society
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• v.18 no.6
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• pp.1135-1142
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• 2017

In this paper, we propose IoT based smart CCTV security service to prevent crime in blind spot and prevent unexpected fire or danger. In the proposed method, a RC (Radio Control) car is made using Raspberry pie, and a camera and various modules are installed in an RC car. It was then implemented using Raspbian O / S, Apache Web Server, Shell script, Python, PHP, HTML, CSS, Javascript. The RC car provides a security service that informs the manager of the situation by judging the risk of the scene with modules such as video, voice and temperature. Experimental results show that the transmission time of video and audio information is less than 0.1 second. In addition, real-time status transmission was possible in AVG, emergency, and manual mode. It is expected that the proposed method will be applied to the development of smart city by applying it to unmanned vehicles, drones and the like.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.2
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• pp.959-962
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• 2005

Recently, business integration and interoperability of between the heterogeneous applications are requested by rapid growth of web. Web Services that self-contained for platform and programming language is appeared used to XML of standard data format. Such amid Fast Web Services attract attention at fields necessary to bring rapid communication like Mobile and RFID. In this paper, we inquired about ASN.1 of ITU-T and IS0/IEC standard that a central role of data transform. And we studied encoding process of between ASN.1 and XML for transform SOAP massage of a massage transfer mode of Web Services to binary data.

• Journal of the Korea Society for Simulation
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• v.28 no.4
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• pp.67-74
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• 2019

As the market for Internet of Things (IoT) service grows, the security issue of the data from IoT devices becomes more important. In this paper, we implemented a cryptographic library for confidentiality of sensor data from Android Things based IoT services. The library made use of the SEED algorithm for encryption/decryption of data and we verified the library by implementing a service environment. With the library, the data is securely encrypted and stored in the database and the service environment is able to represent the current sensing status with the decrypted sensor data. The contribution of this work is in verifying the usability of SEED based encryption library by implementation in IoT sensor based service environment.

• Proceeding of Spring/Autumn Annual Conference of KHA
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• 2004.11a
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• pp.393-397
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• 2004

The purpose of this study was to analyze the needs for managerial service for residents in multi-family housing. For the survey and statistical analysis, the questionnaires from 484 residents and 84 housing managers of multi-family housing within the Seoul metropolitan area were used. The analytical methods adopted in this study were frequency, percentage, t-test, and factor analysis. The results of this study are as follow : (1) Basic services within a multi-family housing included management, minimum residential self governance, basic etiquette, and community program. And additional service were categorized by the health and entertainment program, the consumer service program, the residential life services, the information and financial services program, and the children's program. (2) The favorite needs of residents' additional services were the market news and information, the programs related health, the mail services, the health diagnosis service programs etc. But, housing managers' needs were the market news and information, and the flea market. As to the results analyzing the needs for additional service fir residents, it was found there were differences between residents and housing managers.

• Annual Conference of KIPS
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• 2019.05a
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• pp.727-730
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• 2019

본 연구에서는 시맨틱 기반의 상호운용성을 지원하는 Fiesta IoT 온톨로지 모델을 기반으로 Protégé에서 새로운 온톨로지를 추가하여 모델링을 하였다. 이를 통해 KT IoTMakers에서 Open API를 통해 받은 JSON 형태의 데이터를 Jena 프레임워크를 이용하여 RDF 데이터로 변환하였다. 또한, 변환된 RDF 데이터를 Fuseki 서버로 전송하여 저장했으며, SPARQL 질의를 통한 결과를 Daum Map API를 사용하여 웹으로 표현하였다. 이를 통해 사람들이 시맨틱 IoT 매쉬업 서비스를 쉽게 접근할 수 있는 기회를 제공하여 다양한 응용 가능성을 가진다.

• Journal of the Korean Society for Library and Information Science
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• v.23
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• pp.127-163
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• 1992

The proper evaluation of reference services requires qualitative approach as well as quantitative one. The quality of a reference service can be evaluated by how promptly and accurately a librarian responds to the user's questions and also by how much the user is satisfied with the librarian's overall performance in providing the answer. In this study, the reference service of an university library was evaluated by the following procedure : 1. Identification of a group of the most frequently referred Korean government publications through two pre-tests of user surveys. 2. Preparation of 130 questions of bibliographic and factual type from the above publications. 3. Selection of 30 questions which can be answered from the collection of the evaluated library. 4. Mimic requests of reference service by 5 proxies trained on the unobtrusive test method with 30 questions asked at various times of the day and on various days of the week during a period of 5 months. 5. Drawing up of response sheets (by proxies) with descriptive comments on library staffs' question administration, response, attitude, etc. 6. Preparation and coding of data tabulation sheets and final analysis. The conclusions of this study are as follows : 1. The user serveys showed that needs for the library service for government publications were great. The $80\%$ of the government publications users were visiting more than two organizations for access to information and the $37\%$ were getting information directly from the publishers. 2. The librarians of the evaluated library could give correct answers to $53\%$ of 30 (bibliographic and factual) guestions. 3. The correctness of answer was independent of the length of the time spent the librarians. The librarians' grasp of the questions and direction of approach determined the success or failure of the service. 4. The librarians relied too much on the reference library catalog which doesn't include many of the government publications of their own collection. 5. The $79\%$ of the failure of the service were due to the librarians' lack of knowledge as to the information source for government publications and the unsystematic method of approach to it.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.10a
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• pp.123-126
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• 2007

This paper presents the SVC (Scalable Video Coding) scheme which enables the AT-DMB (Advanced Terrestrial - DMB) video service in enhancement layer, while keeping the current T-DMB video service in base layer. But, it is very complicate to implement the SVC encoder and so it is necessary to analyze the complexity and performance for SVC encoder's structures and coding parameters. In this paper, through computer simulations, SVC coding parameters are tested and then, based on these results, three types of SVC encoder models are compared from the viewpoint of the complexity and performance.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.11
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• pp.2015-2020
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• 2007

This paper presents the SVC(Scalable Video Coding) scheme which enables the AT-DMB(Advanced Terrestrial-DMB) video service in enhancement layer, while keeping the current T-DMB video service in base layer. But, it is very complicate to implement the SVC encoder and so it is necessary to analyze the complexity and performance for SVC encoder#s structures and coding parameters. In this paper, through computer simulations, SVC coding parameters are tested and then, based on these results, three types of SVC encoder models are compared from the viewpoint of the complexity and performance.