• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.1
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• pp.51-58
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• 2008

We propose a new duplex which does not require guard resources in MIMO environments. In the proposed duplex, two virtual channels in spatial domain are generated by preceding and postcoding MIMO channels, not to use guard resources in either the time or frequency domain. The capacity can be improved by properly selecting precoder and postcoder. We show the improved capacity of the proposed duplex outperforms conventional duplexes even without guard resources.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2011.04a
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• pp.652-655
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• 2011

건축, 구조, 기계, 전기, 토목, 조경 등 IT와 관련된 다양한 산업 분야에서는 각 산업의 기획, 생산, 운영등 단계별로 다양한 주제를 가지고 논의 및 시뮬레이션을 통하여 각 업체별로 의사를 개진해 나간다. 그러나 업종별 공정에 맞는 커뮤니케이션이 원활히 이루어져 나가기는 힘들다. 이러한 이유 중 가장 큰 부분은 데이터들이 다양한 뷰어(Viewer)들을 통하여 2차원적으로 보는 부분이 큰 비중을 차지하는 것에 비해 실제 결과물은 3차원적으로 다루어지고 있기 때문에 과정과 결과간의 격차로 인하여 벌어지는 문제가 크다. 각각 다양한 분야에서 생산되는 데이터들의 불확실성, 표현의 애매모호함으로 인하여, 이전 공정 단계에서 받은 데이터들을 현재의 공정 단계에 맞는 데이터로 변환되는 과정이 생긴다. 불필요한 과정들이 반복되는 사이 모든 공정이 지연되고, 많은 예산이 소모되는 등 많은 문제들이 발생되고 있다. 따라서 본 연구에서는 다채널을 활용한 VR 시뮬레이터로 몰입감을 높이고, 실제와 유사한 실감형 시뮬레이션으로 엔지니어링 VR 시뮬레이션이 가능함을 알 수 있었다. 향후에는 사용자의 용도와 목적에 따라 다양한 분야에서 활용의 범위가 넓을 것으로 기대되며, 많은 공간과 비용이 드는 현재의 다채널 시뮬레이터 형태를 보다 공간과 비용의 소모가 적고, 이동성을 갖춘 이동형 다채널 VR 시뮬레이터에 관한 연구가 필요하다.

• The Journal of the Acoustical Society of Korea
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• v.17 no.5
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• pp.63-68
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• 1998

광대역 정보통신망(B-ISDN)에 적합한 직접 제공법의 스트리밍모드 비연결형 서버 는 단일 셀의 전송시간 동안 셀의 송·수신 및 룩업(lookup)을 수행해야 한다는 시간적인 제약을 받기 때문에 버스트 트래픽(Burst Traffic)이 발생했을 경우 셀 손실이 많다는 단점 을 가지고 있다. 따라서 본 논문에서는 ATM 망의 스트리밍 모드 비연결형 서버가 고속으 로 데이터를 처리하여 셀 손실을 줄일 수 있도록 하기 위해 DBLCAM을 제안하였으며, 입 력 VPI(Virtual Path Identifier)/VCI(Virtual Channel Identifier)에 대한 연결 번호를 출력하 는 기능의 포워딩 테이블 VPC맵을 제안된 DBLCAM과 이중 포트 SRAM을 이용하여 설계 하였다.

• Korean Journal of Computational Design and Engineering
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• v.15 no.3
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• pp.167-177
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• 2010

In recent years, the use of high-resolution tiled display system which does not have restrictions on the size of the screen and implements various layout of tile is increasing in order to evaluate the digital mock-up in physical scale or explore large engineering data set in detail. In this study, we developed multi-channel distributed visualization system which provides a virtual reality-based visual contents using 3D open-source graphics engine. Efficient data structures and exchange methods were proposed as a scene synchronization technology in PC cluster environments. DLP-Cube based tiled visualization system which provides $5{\times}2$ layout of display wall was developed and we validated our approach using this system. In addition, we introduced integrated control program that administrates PC cluster environment in remote and controls the layout of display channels.

• The Transactions of the Korea Information Processing Society
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• v.6 no.11S
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• pp.3367-3378
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• 1999

ATM technology, which acts as a representative high-speed bandwidth technology, plays an important role in Internet environment. ATM network, supporting QoS(Quality of Service) and various traffic characters in high speed, configures many VPC(Virtual Path Connection)/VCC(Virtual Channel Connection). It is important to guarantee the QoS of each connection and it is necessary for the network manager to search element affecting the QoS of VPC/VCC and to control ATM network correctly. In the paper, the management information of VPC/VCC, that ATM network manager Using the fault notification for ATM switch, we can manage the configuration, fault and performance of ATM network. Thus, we extracted the configuration, fault and performance monitoring item from the ATM-MIB and SNMP M4 Network Element View MIB. And we designed the ATM network configuration, fault and performance management system based on the extracted item.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.842-847
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• 2005

This paper proposes a novel real-time EMG pattern recognition for the control of a multifunction myoelectric hand from four channel EMG signals. To cope with the nonstationary signal property of the EMG, features are extracted by wavelet packet transform. For dimensionality reduction and nonlinear mapping of the features, we also propose a linear-nonlinear feature projection composed of PCA and SOFM. The dimensionality reduction by PCA simplifies the structure of the classifier, and reduces processing time for the pattern recognition. The nonlinear mapping by SOFM transforms the PCA-reduced features to a new feature space with high class separability. Finally a multilayer neural network is employed as the pattern classifier. We implement a real-time control system for a multifunction virtual hand. From experimental results, we show that all processes, including virtual hand control, are completed within 125 msec, and the proposed method is applicable to real-time myoelectric hand control without an operation time delay.

• Proceedings of the KSME Conference
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• 2001.11b
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• pp.377-382
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• 2001

A suboptimal control law in turbulent pipe flow is derived and tested. Two sensing variables ${\partial}p/{\partial}{\theta}\;|_w\;and\;{\partial}{\upsilon}_{\theta}/{\partial}r\;|_w$ are applied with two actuations ${\phi}_{\theta}$ and ${\phi}_r$. To test the suboptimal control law, direct numerical simulations of turbulent pipe flow at $Re_r=150$ are performed. When the control law is applied, a $13{\sim}23%$ drag reduction is achieved. The most effective drag reduction is made at the pair of ${\partial}{\upsilon}_{\theta}/{\partial}r\;|_w$ and ${\theta}_r$. An impenetrable virtual wall concept is useful for analyzing the near-wall suction and blowing. The virtual wall concept is useful for analyzing the near-wall behavior of the controlled flow. Comparison of the present suboptimal control with that of turbulent channel flow reveals that the curvature effect is insignificant.

• Journal of Institute of Control, Robotics and Systems
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• v.6 no.4
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• pp.295-304
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• 2000

In the teleoperation system, force and velocity signals are communicated between a master and a slave robot. The addition of force feedback to a teleoperation system benefits the operator by providing more information to perform given tasks especially for tasks requiring contact with environment. When the master and slave arms are located in different places, time delay is unavoidable and it is well known that the system can become unstable when even a small time delay exists in the communication channel. The control scheme proposed in this paper is based on the estimator with virtual master model. Delayed signal from the master robot can be replaced by the estimated signal with the virtual master model. This control scheme makes the teleoperation system stable for the given time delay while the conventional scheme is not. This new control scheme is verified through numerical simulations and an experiments using the dual axis testbed of the teleoperation system.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.7
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• pp.1403-1410
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• 1997

Because streaming mode connection server suitable to wide area ATM networks performs transmission, reception and lookup with time restriction for the transmission time of a cell, it has demerits of large cell loss incase that burst traffic occurs. Therefore, in this paper to decrease cell loss we propose a high speed CAM (Content Addressable Memory) which is capable of processing data of streaming mode connections server at a high speed. the proposed CAM is applied to forwarding table VPC map which performs function to output connection numbers about input VPI(Virtual Path Identifier)/VCI(Virtual Channel Identifier). The designed high speed CAM consist of DBL(Dual Bit Line) CAM structure performed independently write operation and match operation and two-port SRAM structure. Also, its simulation verification and full-custom layout is performed by Hspice and Composs tools in 0.8 .$\mu$m design rule.

• The Journal of the Acoustical Society of Korea
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• v.31 no.6
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• pp.373-383
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• 2012

The performance of underwater acoustic communication system is sensitive to the Doppler shift and ISI(Inter-Symbol Interference). Therefore, the simulation algorithm needs to consider time-spread due to multipath arrivals which cause the ISI, and time-varying Doppler shift along with moving source and receiver. For this purpose, VirTEX(Virtual Time series EXperiment) based on Ray model has been developed. In this paper, VirTEX is used to compare the characteristics of ocean waveguide from the experimental data and illustrate the performance. The CIR(Channel Impulse Response) that characterizes the multipath arrivals with representative time-spread due to multipath arrivals is compared between numerically simulated and experimental probe signal. Also, the communication performance analysis for BER(Bit Error Rate) is compared between numerically simulated and experimental data signal. As a result, VirTEX can be useful as a simulation tool for evaluating the performance of underwater acoustic communication system.