• Annual Conference of KIPS
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• 2010.11a
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• pp.1233-1236
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• 2010

클라우드 컴퓨팅 시스템은 방대한 정보와 자료를 가진 컴퓨팅 시스템으로 해커의 공격 대상이 되기쉽다. 또한 복잡한 구조를 가지기 때문에 취약점이 발생하기 쉬워 체계적인 보안 분석이 필요하다. 현재 클라우드 컴퓨팅 보안 요구사항 분석이나 권고 사항 연구를 위해 많은 국제 협의기구가 활발히 활동 중이다. 하지만 협의기구들의 연구 활동은 서비스 유형에 따라 사업자 기준에서 보안 분석이 이루어지고 있다. 클라우드 컴퓨팅 서비스가 보다 활발히 발달하기 위해서는 클라우드 컴퓨팅 서비스를 이용하는 사용자들을 세분화하고 그들에 맞는 보안 서비스가 제공되어야 한다. 본 논문에서는 기존의 보안 분석들과 다르게 사용자 기준에서 분석한 클라우드 컴퓨팅 서비스의 보안 분류를 제시한다.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.13 no.3
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• pp.1-7
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• 2013

We perform simulation. It is that LED panels is fixed and moving the terminal with PD in order to analyze the performance of visible-light wireless communication system based on MIMO under variety of the interference environment. And, based on the technology MIMO, we analyzed whether the interference caused by external light to give what effect changes in the quality of the communication channel. The distortion due to time delay in channel transmission must be compensated by using the equalizer. Especially, use of equalizer is need absolutely as data rate becomes high speed. Therefore, in this paper, the system VLC, were analyzed BER performance using channel equalization.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.9
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• pp.1-8
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• 2007

In this paper, the new beamforming is proposed for an orthogonal frequency division multiplexing(OFDM) system with multi-input multi-output(MIMO). Through the proposed Pre-FFT beamforming technique for MIMO-OFDM, the multibeams are formed toward each multi-transmitter antenna of the desired user. The proposed beamforming for MIMO-OFDM can reduce cochannel interference and get diversity gain in the multi-user environment. Therefore, the performance of MIMO-OFDM system is very improved. BER performance improvement of the proposed approach is investigated through computer simulation by applying it to MIMO-OFDM system in the multi-user environment.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.4 no.3
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• pp.193-198
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• 2003

A rotor dynamic analysis is implemented to confirm the vibration stability of the high speed centrifugal chiller coupled with gear system. As the rotating speed of the centrifugal chiller under investigated is increased up to 17,605 rpm at the pinion rotating part, the bearing instability is getting higher and, furthermore, the rotor-bearing system might experience a few critical speed which lead to system failure due to the excessive vibration. In this study, considering the loading capacity and stability conditions, offset journal bearings are adopted for the pinion rotating system and general cylindrical bearing are used for motor part. From the modal analysis, the system is found to be stable as the synchronous rotating frequency does not come across with any whirl natural frequency and, in addition, the critical damping ratio which shows the damping characteristics of the system are positive over the all operating ranges. From these results the authors confirm the vibration stability of the rotor-bearing system suggested in this study.

• Proceedings of the KIEE Conference
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• 2001.07c
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• pp.1861-1863
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• 2001

본 연구에서는 국내에서도 아직 초기단계 기술이라고 할 수 있는 간섭계를 이용한 주요 시설물(변전소등) 안전 감시 혹은 항만 감시 및 방어용 광섬유 격자 그물망 구현을 위한 광섬유 시스템 적용성을 연구한 것이다. 연구에서는 마흐젠더 간섭계의 구성에 비해 구성이 용이한 Sagnac간섭계를 구성 실험하였다. 이 간섭계의 성능 검증을 위하여 1550nm의 중심파장을 방사하는 레이저, 싱글모드 광섬유, 3${\times}$3 커플러 등의 광소자를 사용하였고, 광섬유의 길이의 변화를 주기 위하여 PZT 위상 변조기에 교류 전원을 인가하여 PZT 위상 변조기의 진동을 유도하였다. 또한, 전체 길이 약 180cm, 17${\times}$7, 철봉의 직경 6m의 철망 구조물을 제작후, 센서 부분의 역할을 담당한 광섬유 케이블을 일정한 간격으로 철망 구조물에 케이블 타이로 고정하였다. 철망 구조물에서 발생할 수 있는 각종 외부 가진에 대해, 철망 구조물에 가속도계를 설치하여, Sagnac 간섭계에서의 광 간섭 신호와 가속도계의 신호를 비교 검증 하였다. 본 실험결과를 통하여 광섬유 펜스는 주요 시설물(변전소등) 안전 감시 혹은 항만 감시 및 방어용 경보 시스템에 적합하다고 판단된다.

• The Journal of the Korea institute of electronic communication sciences
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• v.11 no.5
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• pp.459-464
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• 2016

The mobile communication service is widely used and the repeaters is rapidly increasing because of the extending service areas. we propose a new Signed CMA(: Constant Modulus Algorithm) algorithm for ICS(: Interference Cancellation System) as a larger service area of mobile communication service. The proposed Signed CMA algorithm improved performances by adjusting step size values. We showed that the proposed algorithm could improve the Mean Square Error(: MSE) performance of Signed CMA. MATLAB(: Matrix Laboratory) is employed to analyze the proposed algorithm and to compare it with the experimental results. At the convergence of 1000 iteration state, the MSE(: Mean Square Error) performance of the proposed Signed CMA algorithm with step size of 0.0065 is about 5 dB better than the conventional CMA algorithm.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2005.11a
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• pp.203-206
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• 2005

차량 진단 기능이 탑재된 원격 서버, 제어 신호 중계 기능을 가진 휴대폰용 어플리케이션, 그리고 신호 변환을 위한 converting 보드를 사용하여 기존의 차량진단기(scanner)와 동일한 기능을 가지는 원격차량진단 시스템을 제안한다. 원격 서버에서 직접 차량 진단 기능을 수행함으로써 진단 이력에 대한 자동 관리가 가능하며 다양한 부가 서비스를 연계하여 제공할 수 있다. 또한 신규 차종에 대하여 원격 서버 프로그램의 변경으로 대응이 가능하므로 기존 방식처럼 신규 차종에 대한 개별 upgrade가 필요 없다. 제안한 방식은 저가의 진단 시스템 구축이 가능하므로 영업소에서만 사용되던 차량 진단기를 개별 사용자가 사용할 수 있게 해준다. 또한 bluetooth의 Serial Port Profile을 기반으로 휴대전화기와 converting 보드간의 선을 제거함으로써 사용자가 간단하게 진단 어플리케이션이 탑재된 bluetooth handset에서 진단을 할 수 있다. 실험을 통하여 제안한 방식의 실제 환경에서 잘 동작함을 검증하였다.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.17 no.2
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• pp.161-169
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• 2004

This paper deals with system identification of a three-story building model with active mass damper (MID) for the controller design. Observer Kalman filter identification (OKID) technique is applied to find the relationship between the experimental results of the input and output. The inputs to the building model with MID are ground accelerations and motor command signal, which are, respectively, simulated earthquake and equivalent control force. The outputs are each floor acceleration and MID acceleration. The MID controller is designed based on the experimentally identified building system. Finally it is shown that experimental results agree accurately with simulated results.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.30 no.2
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• pp.159-167
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• 2017

The purpose of this study is to accurately estimate the wind-induced responses of a tall building structure for using the estimated responses in the process of calculating the optimal force of an active control device. Kalman filter was used for the estimation process and a 3-storied model structure on a shaking table was tested for the verification of the estimation accuracy. The system matrices of the model were constructed based on the mode parameters obtained by the system identification. The estimated displacement matched up well with the measured one. Finally, the wind-induced responses of a real 39-storied building structure excited by the typhoon MUIFA were estimated.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.12
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• pp.2140-2150
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• 2006

The RSS Reader is a software application that assist users easily to read and collect contents which are frequently changeable syndicated contents of RSS format that published on the web. This paper presents a formula software design based on RUP object-oriented design method for implementing the RSS Reader. We extract a use case based on requirements for implement of the RSS Reader and propose a domain concept model by. Using above artifacts, we extract event to generate between users and, the RSS Reader and logical architecture. So, we design classes and packages of the RSS Reader. As proposed a formula software design about the RSS Reader in early stage, it can make the RSS Reader with a variety of characters easily based on these.