• Structural Monitoring and Maintenance
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• 제4권3호
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• pp.221-236
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• 2017

In this study, the feasibility of vibration-based damage alarming algorithms are numerically evaluated for wind turbine tower structures which are subjected to harmonic force excitation. Firstly, the algorithm of vibration-based damage alarming for the wind turbine tower (WTT) is visited. The natural frequency change, modal assurance criterion (MAC) and frequency-response-ratio assurance criterion (FRRAC) are utilized to recognize changes in dynamic characteristics due to a structural damage. Secondly, a finite element model based on a real wind turbine tower is established in a structural analysis program, Midas FEA. The harmonic force is applied at the rotor level as presence of excitation. Several structural damage scenarios are numerically simulated in segmental joints of the wind turbine model. Finally, the natural frequency change, MAC and FRRAC algorithm are employed to identify the structural damage occurred in the finite element model. The results show that these criteria could be used as promising damage existence indicators for the damage alarming in wind turbine supporting structures.

• Journal of Computing Science and Engineering
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• 제2권4호
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• pp.412-427
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• 2008

We propose ID-exchange protocol for Connectionless Location-Awareness Service (CLAS) to locate mobile nodes in indoor sensor network. When adapting location-awareness service to sensor network, the target system must be designed in accordance with various metrics which reflect the system requirement. We especially consider sustainability of the existing service which has been provided for its original purpose, such as environmental monitoring. The detailed meaning of sustainability here is that, even if location-awareness service is newly added to the existing service, the system must be assured to retain a stable network condition, and to deal with newly caused traffic properly. The CLAS ID-exchange protocol is especially designed for fixture and mobile nodes communication to achieve these properties. The protocol operates on 802.15.4 MAC layer to make mobile node work independently of the procedure to build routing table of fixture node, so a stable routing condition can be achieved even if there are many mobile nodes. Moreover, the dedicated frequency channel is assigned only for this protocol, so that traffic caused by location-awareness service can be distributed to another channel. A real system adapting the protocol was implemented to monitor fire and authorities' positions. We verified the overhead and elapsed time for location-awareness. The result shows the proposed protocol has a high performance in detecting speed, traffic distribution, and stability of overall network.

• Annual Conference of KIPS
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• 한국정보처리학회 2002년도 추계학술발표논문집 (중)
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• pp.1415-1418
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• 2002

최근 정보 통신 기술의 발달에 따라 음성 서비스 등과 같은 단일 서비스를 제공하던 무선 통신망이 음성, 데이터, 고화질 정지화면, 동영상 및 다양한 정보형태의 멀티미디어 서비스를 추구하고 있다. 이처럼 다양한 종류의 멀티미디어 트래픽을 지원하기 위해서는 매체 접근 제어(MAC) 프로토콜이 필요하다. 본 논문에서는 서로 다른 종류의 트래픽이 혼재된 무선 ATM 환경에서 폭주제어 정보를 가지고 각 트래픽 클래스의 QoS를 만족할 수 있는 동적 자원 할당 방식 기반의 MAC 프로토콜을 제안한다. 각 트래픽 클래스의 데이터 전송 스케줄링을 제안함으로서 CBR이나 VBR의 실시간 데이터의 손실을 최소화하고 네트워크 상태에 따른 ABR 트래픽 클래스에 최소의 고정적인 대역폭을 할당함으로서 실시간 비실시간 데이터의 비효율성 문제 해결 방안을 제시한다. 그리고 각각의 트래픽 모델에 대한 허용 테스트 식을 제공함으로서 다른 실시간 또는 비실시간 채널에 영향을 수지 않고 새로운 채널을 설정한 수 있는 방안을 제시한다.

• Journal of the Korea Institute of Information and Communication Engineering
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• 제10권11호
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• pp.1996-2001
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• 2006

Open System Authentication Method, Shared Key Method, Mac Based Authentication Method are very hard to use in wireless network that needs security. So now, many researches have been performed about 802.1x and user authentication method applying PKI. but certificate verification protocol has been used abolished list called CRL since it's first usage of PKI, there were still has a problem about distribution point. This paper applied CVS to use CA direct not to use CRL and OSCP server in order to improve this problems. Also It suggested the system that can make authentication steps more shorter using authentication server and Mutual authentication system by public certificate(small size/low speed wireless terminal can access to wireless network fast and safely)

• Journal of Information Processing Systems
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• 제16권3호
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• pp.599-611
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• 2020

With the application and promotion of biometric technology, biometrics has become more and more important to identity authentication. In order to ensure the privacy of the user, the biometrics cannot be stored or manipulated in plaintext. Aiming at this problem, this paper analyzes and summarizes the scheme and performance of the existing biometric authentication system, and proposes an iris-based ciphertext authentication system based on fully homomorphic encryption using the FV scheme. The implementation of the system is partly powered by Microsoft's SEAL (Simple Encrypted Arithmetic Library). The entire system can complete iris authentication without decrypting the iris feature template, and the database stores the homomorphic ciphertext of the iris feature template. Thus, there is no need to worry about the leakage of the iris feature template. At the same time, the system does not require a trusted center for authentication, and the authentication is completed on the server side directly using the one-time MAC authentication method. Tests have shown that when the system adopts an iris algorithm with a low depth of calculation circuit such as the Hamming distance comparison algorithm, it has good performance, which basically meets the requirements of real application scenarios.

• Journal of Semiconductor Engineering
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• 제2권2호
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• pp.130-135
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• 2021

Recently, deep neural networks (DNNs) are actively used for action control so that an autonomous system, such as the robot, can perform human-like behaviors and operations. Unlike recognition tasks, the real-time operation is essential in action control, and it is too slow to use remote learning on a server communicating through a network. New learning techniques, such as reinforcement learning (RL), are needed to determine and select the correct robot behavior locally. In this paper, we propose an energy-efficient DNN processor with a LUT-based processing engine and near-zero skipper. A CNN-based facial emotion recognition and an RNN-based emotional dialogue generation model is integrated for natural HRI system and tested with the proposed processor. It supports 1b to 16b variable weight bit precision with and 57.6% and 28.5% lower energy consumption than conventional MAC arithmetic units for 1b and 16b weight precision. Also, the near-zero skipper reduces 36% of MAC operation and consumes 28% lower energy consumption for facial emotion recognition tasks. Implemented in 65nm CMOS process, the proposed processor occupies 1784×1784 um2 areas and dissipates 0.28 mW and 34.4 mW at 1fps and 30fps facial emotion recognition tasks.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• 제25권2호
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• pp.96-102
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• 2011

There are many problems with the fire detection devices being used in currently, because it is difficult to find location of the source of fire and determine where devices are working or not. In this paper, we proposed fire detection and rescue system using wireless sensor network that can be real-time monitoring and determine safe exit. Fire detection and rescue system based on ubiquitous sensor network can know exactly source of fire and help determine rescue tactics using sensing data from wireless sensor nodes. Transmitted wirelessly in real-time thermal sensor and gas sensor information to analyze the GUI to monitor the status information output to the screen by use of a system implemented in everyday life, looked at the possibility.

• Journal of the Korean Institute of Telematics and Electronics A
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• 제32A권5호
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• pp.42-53
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• 1995

Token bus protocols have been sidely accepted for Medium Access Control (MAC) in real-time networks such as those used in factory automation, distributed process control, nuclear power plant, aircraft and spacecraft. Token bus protocols provide timer-controlled priority mechanism, which offers multiple level of privilege of medium access to different type of traffic. This paper presents and approximate analytical model for the evaluation of variance of waiting time in the time-controlled proiority scheme of token bus protocols. Token bus system is assumed to be operated with singe-service discipline which is the practical case of real-time networks such as those used in distributed process control and factory automations. The approximate analytical model is validated by comparison with the simulation resuls.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 한국에너지공학회 1999년도 추계 학술발표회 논문집
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• pp.143-148
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• 1999

A distributed real-time system that is being wed now is usually divided into three level : higher level, middle level, and lower level. The higher level network is usually called an information network, the middle level is called a control network, and the lower level is called a field network or a divice network. This dissertation suggests and implements a middle level network which is called PICNET-NP (Plant Implementation and Control Network for Nuclear Power Plant). PICNET-NP is based partly on IEEE 802.4 token-passing bus access method and partly on IEEE 802.3 physical layer. For this purpose a new interface, a physical layer service translator, is introduced. A control network using this method is implemented and applied to a distributed real-time system.

• Journal of Korea Multimedia Society
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• 제11권6호
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• pp.835-844
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• 2008

ZigBee devices are limited in resources especially on power and computational capacity but also require real-time operation at MAC layer. Therefore, it is important to take those requirement into consideration of system software design. In this paper, we proposed a compact system software design to support simultaneously ZigBee and IEEE802.15.4. The design strictly respects the resource and real-time constraints while being optimized for specific functions of both Zigbee and IEEE802.15.4. Various evaluations are done to show significant metrics of our design.