• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.170.4-170
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• 2001

Safety and confidence of the communications network is the main purpose for the unmanned control systems, in terms of appling a satellite communications network to the water treatment and supply plant communication system. Since the unmanned control systems were applied in the industrial site, the lack of confidence on the communications network has been presented continuously as a main problem for the unmanned and automation systems. Therefore, satellite communications network was presented as one of the methods to solve this problem, supporting the wire used telecommunication. In addition to the safety of a communications network, there is the retrenchment of expenditure. This dual communications network has ...

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1996년도 Proceedings of the Korea Automatic Control Conference, 11th (KACC); Pohang, Korea; 24-26 Oct. 1996
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• pp.173-176
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• 1996

This paper deals with the problem of designing an adaptive regulator in order to improve transient performance in time-response when the linear state-space model of the plant contains unknown parameters which vary within prescribed bounds. The whole possible parameter space is divided into some subspaces and multiple models and controllers are established from the view point that each controller gives satisfactory transient behavior for systems corresponding to each parameter subspace. Based on time-response and an associated cost function, an appropriate controller is selected on-line out of multiple controllers.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 ITC-CSCC -1
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• pp.149-151
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• 2002

We had been developing the variety of parallel processing systems in order to improve the processing speed of visual media applications. These systems were using multi-access memory system(MAMS) as a parallel memory system, which provides the capability of the simultaneous accesses of image points in a line-segment with an arbitrary degree, which is required in many low-level image processing operations such as edge or line detection in a particular direction, and so on. But, the performance of these systems did not give a faithful speed because of asynchronous feature between MAMS and processing elements. To improve the processing speed of these systems, we have been investigated a pipelined parallel processing system using MAMS. Although the system is considered as being the single instruction multiple data(SIMD) type like the early developed systems, the performance of the system yielded about 2.5 times faster speed.

• Journal of information and communication convergence engineering
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• 제2권2호
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• pp.67-70
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• 2004

In this paper, we propose two novel high-rate high-performance space-time codes for multiple-input multiple-output (MIMO) systems. When $n_T$ transmit antennas and When $n_R$ ＝ When $n_T$ receive antennas are deployed, the two proposed codes respectively offer transmission rates of (When $n_T$ -1) and (When $n_T$ -2) symbols per channel use and diversity orders of 3 and 5. As a consequence, our proposed codes allow the MIMO systems to employ a simple detection technique based on QR decomposition. Moreover, for equal or even higher spectral efficiencies, our proposed codes always provide much better bit error rate (BER) performances than V-BLAST architecture does when When $n_R$ ＝ When $n_T$. Computer simulation is given to verify performances of our proposed codes.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제6권1호
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• pp.24-45
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• 2012

In this paper, we present a survey of security and privacy preserving issues in M2M communications in Cyber-Physical Systems. First, we discuss the security challenges in M2M communications in wireless networks of Cyber-Physical Systems and outline the constraints, attack issues, and a set of challenges that need to be addressed for building secure Cyber-Physical Systems. Then, a secure architecture suitable for Cyber-Physical Systems is proposed to cope with these security issues. Eventually, the corresponding countermeasures to the security issues are discussed from four aspects: access control, intrusion detection, authentication and privacy preserving, respectively. Along the way we highlight the advantages and disadvantages of various existing security schemes and further compare and evaluate these schemes from each of these four aspects. We also point out the open research issues in each subarea and conclude with possible future research directions on security in Cyber-Physical Systems. It is believed that once these challenges are surmounted, applications with intrinsic security considerations will become immediately realizable.

• Journal of Communications and Networks
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• 제4권4호
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• pp.336-343
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• 2002

A major challenge for next generation mobile communication is capturing the system architecture’s complexity with all its internal and external dependencies. Seamless integration of heterogeneous environments in all system parts is a key requirement. Moreover, future systems have to consider the different evolution cycles of individual system parts. Among those, services are expected to change the fastest. With respect to these considerations, we propose an overall architecture for next generation mobile communication systems. It covers all system parts from wireless transmission to applications including network and middleware platform. Our approach focuses on adaptability in terms of recon- figurability and programmability to support unanticipated system evolution. Therefore, we consider abstraction layers which consist of adaptable cooperating components grouped by open platforms rather than rigid system layers. In addition to that, we introduce cross-layer cooperation allowing an efficient use of the available resources. Specific scenarios illustrate the feasibility of our approach.

• 한국통신학회논문지
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• 제32권11A호
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• pp.1138-1145
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• 2007

In wireless communications, chaotic communications have been a field of interest due to its low complexity in hardware implementation and low power consumption in chaotic signal generation. Among the modulation schemes using the chaotic signal, Differential Chaos Shift Keying (DCSK) is a robust non coherent technique. As in the conventional communication systems, chaos-based systems are required to provide reasonable bit error performance in the presence of a narrow-band signal coming from any other systems. The frequency band of this foreign narrow band signal may lie within the bandwidth of the chaos-based systems. This situation may occur when chaotic signal transmission is done in the presence of other conventional communication system. This paper has evaluated the performance of the non coherent differential chaos shift keying (DCSK) system under the presence of conventional non-chaotic transmit reference system. Both systems are assumed to have same data rates. The mathematical expressions for the bit error rate (BER) are derived with computer simulations to verify the analytical results.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2002년도 ICCAS
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• pp.93.6-93
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• 2002

Many livings form groups that we consider as collective systems. Their collective behaviors are good model for the development of useful distributed systems. In this paper, We discussed the group of motile elements that is described by simple model. The dynamics of each element is described by simple kinematics, but the group shows various types of motions. In addition, we found out the formation of the group changes by modifying rc which is an optimum distance between each element. This modification shows us to observe close-packed structure, face-centered lattice, sim pie lattice and double file.

• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송공학회 2009년도 IWAIT
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• pp.108-113
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• 2009

Significant attention has recently been drawn to digital home photo albums that use face detection technology. The tendency can be found in home photo albums that people prefer to allocate concerned objects in the center of the image rather than the boundary when they take a picture. To improve detection performance and speed that are important factors of face detection task, this paper proposes a face detection method that takes spatial context information into consideration. Experiments were performed to verify the usefulness of the proposed method and results indicate that the proposed face detection method can efficiently reduce the false positive rate as well as the runtime of face detection.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2005년도 추계학술발표대회 및 정기총회
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• pp.155-158
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• 2005

본 논문에서는 MPEG 의 멀티미디어 응용 표준인 MAF(Multimedia Application Format)를 기반으로, 효율적인 비디오 콘텐츠의 검색 및 활용을 위한 통합 미디어 구조, 즉 비디오 MAF 를 제안한다. 제안하는 비디오 MAF 는 ISO 미디어 포맷을 기반으로 하고 단일의 비주얼 스트림과 다중 음성을 지원하기 위한 다수의 오디오 스트림, 내용기반의 정보를 포함하는 메타데이터, 그리고 비디오 콘텐츠의 대표 이미지를 동시에 포함하는 구조이다. 제안하는 파일포맷의 유용성을 검증하기 위해 비디오 MAF 로 생성 및 해석할 수 있는 부호기(encoder)와 복호기(decoder)를 설계하고 구현하여, 통합 미디어에 내재된 메타데이터를 이용한 효율적인 검색과 멀티트랙의 오디오 스트림을 활용한 다중 음성에 대한 지원이 가능함을 확인하였다. 또한 내재된 대표이미지는 비디오 콘텐츠에 대한 브라우징이 효과적으로 활용됨을 확인하였다.