• 한국컴퓨터정보학회논문지
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• 제8권3호
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• pp.144-149
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• 2003

멀티미디어 데이터는 실시간 제약을 갖고 있기 때문에 암호화/복호화로 인한 지연이 실시간 제약에 미치는 영향을 최소로 하면서 암호화를 하기 위해서는 네트워크 트래픽과 부하에 적응하여 암호화 알고리즘을 변경하기 위한 방법이 필요하다. 또한 다수가 참여하는 멀티미디어 서비스 진행 중에 서비스 이용을 중지한 사용자는 RTP payload의 암호화 키를 알고 있기 때문에 이 사용자로부터 RTP payload를 보호하기 위해서는 암호화 키를 변경하기 위한 방법이 필요하다. 따라서 본 논문에서는 RTP payload의 암호화를 위해 암호화 알고리즘과 암호화 키를 변경하기 위한 RPT 보안제어 프로토콜을 설계하고 구현하였다.

• 한국컴퓨터정보학회논문지
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• 제20권11호
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• pp.25-30
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• 2015

The enormous increase of data with the development of the information technology make internet users to be hard to find suitable information tailored to their needs. In the face of changing environment, the information filtering method, which provide sorted-out information to users, is becoming important. The data on the internet exists as various type. However, similarity calculation algorithm frequently used in existing collaborative filtering method is tend to be suitable to the numeric data. In addition, in the case of the categorical data, it shows the extreme similarity like Boolean Algebra. In this paper, We get the similarity in SNS user's information which consist of the mixed data using the Gower's similarity coefficient. And we suggest a method that is softer than radical expression such as 0 or 1 in categorical data. The clustering method using this algorithm can be utilized in SNS or various recommendation system.

• 융합보안논문지
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• 제2권1호
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• pp.49-57
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• 2002

멀티미디어 정보 전송을 위해 RTP(Real-Time Transport Protocol)을 사용하며, 멀티미디어 정보 보안을 위해서는 RPT의 페이로드를 암호화해야 한다. RPT 페이로드의 암호화를 위해서 암호화/복호화로 인한 지연이 멀티미디어 정보의 실시간 제약에 미치는 영향을 최소로 하면서 네트워크의 트래픽과 부하에 적응하며 암호화 알고리즘을 변경하기 위한 방법이 필요하다. 또한 멀티미디어 서비스 진행 중 서비스 이용을 중지한 사용자는 RPT 페이로드의 암호화 키를 알고 있기 때문에 페이로드를 보호하기 위해서는 암호화 키를 변경하기 위한 방법이 필요하다. 따라서 본 논문에서는 RPT 페이로드의 암호화를 위해, 암호화 알고리즘과 암호화 키를 변경하기 위한 SCPR(Security Control Protocol for RTP)를 설계하고 구현하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 추계학술대회 논문집 학회본부
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• pp.395-397
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• 1996

The existing CPC(Center Position Controller) has unstably performed because of dusts on reflection panel, CCD protector contamination due to high temperature in furnace or other parameters. The reason is that the existing CPC has a Z80 processor as a CPU and only performs low level image processing as a simple edge detector. So the improvement of control system through the development of robust edge detection algorithm overcoming changes of measuring environment is needed. For this, in this study we carefully analyze the image of the strip rolled in occasion that measuring environment is changing, develop the optimal edge detection algorithm to solve the problems, generate the control signal suitable for the existing CPC(Center Position Controller), and propose the capability of application to the actual environment.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 춘계학술대회 논문집 에너지변화시스템부문
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• pp.222-224
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• 2009

This paper proposes analysis data of generation efficiency with tracking method for solar tracking. Tracking algorithm of PV generation is divided the sensor method and program method. Generation efficiency is analyzed the three cases 1-high insolation, 2-low insolation, 3-rapidly changing insolation. Proposed data is possible to apply for development of novel algorithm with hybrid tracking method in this paper. Hereby, This paper is proved the benefit of analyzed data.

• 조명전기설비학회논문지
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• 제15권3호
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• pp.83-90
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• 2001

본 논문은 전력계통에 저주파수 동요현상을 제거하기 위한 목적으로 쓰이고 있는 전력계통 안정화 장치의 적정 파라메타 선정에 관한 알고리즘을 다루었다. 실측에 의한 발전기 시스템의 모델로부터 시스템 제 정수를 구하고, 극좌표 이동법으로 적절한 전력계통 안정화 장치의 파라메타를 Matlab으로 작성하여 구했다. 이 기법으로 선정된 전력계통 안정화 장치의 파라메타로 1기 무한대 계통에 적용한 시뮬레이션 결과는 만족한 만큼의 댐핑 효과를 보았다.

• 조명전기설비학회논문지
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• 제28권5호
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• pp.122-133
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• 2014

This paper deals with the rapid charger which is the mid-type between the slow and fast chargers in the aspect of charging time. In its functions, it can perform the Active Power Filter(APF) function without changing the topology besides the charging function. In addition, to perform the charging and APF function, this paper proposes the mode selection algorithm. The operation of the charger that has APF function and the mode selection algorithm are verified by the simulation and experiment.

• 한국지능정보시스템학회:학술대회논문집
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• 한국지능정보시스템학회 2003년도 춘계학술대회
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• pp.400-409
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• 2003

Collaborative filtering (CF) recommendation is a knowledge sharing technology for distribution of opinions and facilitating contacts in network society between people with similar interests. The main concerns of the CF algorithm are about prediction accuracy, speed of response time, problem of data sparsity, and scalability. In general, the efforts of improving prediction algorithms and lessening response time are decoupled. We propose a three-step CF recommendation model which is composed of profiling, inferring, and predicting steps while considering prediction accuracy and computing speed simultaneously. This model combines a CF algorithm with two machine learning processes, SOM (Self-Organizing Map) and CBR (Case Based Reasoning) by changing an unsupervised clustering problem into a supervised user preference reasoning problem, which is a novel approach for the CF recommendation field. This paper demonstrates the utility of the CF recommendation based on SOM cluster-indexing CBR with validation against control algorithms through an open dataset of user preference.

• Journal of Information Processing Systems
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• 제13권1호
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• pp.68-82
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• 2017

Nowadays, geographic information system (GIS) is developed and implemented in many areas. A huge volume of vector map data has been accessed unlawfully by hackers, pirates, or unauthorized users. For this reason, we need the methods that help to protect GIS data for storage, multimedia applications, and transmission. In our paper, a selective encryption method is presented based on vertex randomization and hybrid transform in the GIS vector map. In the proposed algorithm, polylines and polygons are focused as the targets for encryption. Objects are classified in each layer, and all coordinates of the significant objects are encrypted by the key sets generated by using chaotic map before changing them in DWT, DFT domain. Experimental results verify the high efficiency visualization by low complexity, high security performance by random processes.

• Journal of Information Processing Systems
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• 제14권1호
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• pp.101-128
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• 2018

Thanks to its potential in many applications, Blockchain has recently been nominated as one of the technologies exciting intense attention. Blockchain has solved the problem of changing the original low-trust centralized ledger held by a single third-party, to a high-trust decentralized form held by different entities, or in other words, verifying nodes. The key contribution of the work of Blockchain is the consensus algorithm, which decides how agreement is made to append a new block between all nodes in the verifying network. Blockchain algorithms can be categorized into two main groups. The first group is proof-based consensus, which requires the nodes joining the verifying network to show that they are more qualified than the others to do the appending work. The second group is voting-based consensus, which requires nodes in the network to exchange their results of verifying a new block or transaction, before making the final decision. In this paper, we present a review of the Blockchain consensus algorithms that have been researched and that are being applied in some well-known applications at this time.