• 한국정보통신학회논문지
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• 제9권8호
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• pp.1656-1662
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• 2005

본 논문에서는 기존의 UWB 통신 시스템에서 많이 사용되는 펄스 위치 변조와 펄스 진폭 변조를 사용하여 하나의 펄스로서 여러 비트의 데이터를 전송할 수 있는 M-PPAM(M-ary Pulse Position and Amplitude Modulation) 구조를 소개하였다. 이 방법은 동일한 데이터 전송율을 얻기 위하여 보다 긴 펄스 반복 주기를 사용할 수 있는 장점이 있다. 따라서 실내 환경에서와 같은 다중 경로 페이딩이 심한 경우 대용량의 데이터를 전송하기에 적합하리라고 생각한다. 이때, 다중 사용자를 수용하기 위하여 DS(Direct Sequence) 기법을 사용하였다. 이와 같이 고려된 M-PPAM DS-UWB 수신기의 성능을 가우시안 채널 조건하에서 다중 사용자 간섭을 포함하여 표준 가우시안 근사(Standard Gaussian Approximation)를 사용하여 모델링 하였다. 또한, 수신기의 성능을 시뮬레이션을 통하여 확인하였다.

• 한국정보처리학회논문지
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• 제4권8호
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• pp.1921-1929
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• 1997

본 논문은 멀티미디어 데이타 스트림이 시스템 메모리를 거치지 않고 멀티미디어 데이타 처리기와 통신망 접속기 간에 직접 전달될 수 있는 방법에 대한 연구이다. 멀티미디어 플랫폼에서 통신망 접속기와 멀티미디어 데이타 처리기 간에 추가적인 데이타 전송로 도입이 없이 기존의 단일 데이타 전송로를 통한 양자간의 직접 데이타 전달방법을 제안한다. 그리고 직접전달을 위해 필요한 하드웨어적 구조와 기능을 정의하고, 멀티미디어 데이타가 상호간 전송/반입되는 과정을 제어 흐름도로 기술한다. 제안된 방법과 기존의 일반적인 방법과의 비교 검토를 위해, 직접전달 방법이 시스템 버스의 사용 회수와 사이클을 줄일 수 있음을 보인다.

• 전자통신동향분석
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• 제36권4호
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• pp.23-33
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• 2021

Wireless communication for train control is an active research field. The World Railway Federation in Europe developed GSM-R, which integrates the GSM-based voice call standard and train control signals. To provide advanced railway services, the LTE-R wireless communication system was developed in Korea for passenger services and wireless image information required by the railroad industry. Recently, direct communication technology for autonomous train driving has been studied to decrease the driving interval, and research is being conducted on a hyperloop train control system that runs at a maximum speed of 1,220km/h in a subvacuum environment of 0.001 atmosphere. In this paper, we summarize the trends in wireless communication technologies used for GSM-R/LTE-R railway systems. For future wireless communication in railway systems, we discuss autonomous train driving and the hyperloop railway control system, define wireless communication technology, and discuss trends in domestic and foreign technologies.

• International journal of advanced smart convergence
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• 제4권2호
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• pp.103-108
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• 2015

The electric utility has the responsibility of reducing the impact of peaks on electricity demand and related costs. Therefore, they have introduced Direct Load Control System (DLCS) to automate the external control of shedding customer load that it controls. Since the number of customer load participating in the DLC program are keep increasing, DLCS operators a re facing difficulty in monitoring and controlling customer load. The existing DLCS needs constant operator intervention, e.g., whenever the load is about to exceed a predefined amount, it needs operator's intervention to control the on/off status of the load. Therefore, DLCS operators need the state-of-the-art DLCS, which can control automatically the on/off status of the customer load without intervention as much as possible. This paper presents an intelligent DLCS using the active database. The proposed DLCS is applying the active database to DLCS which can avoid operator's intervention as much as possible. To demonstrate the validity of the proposed system, variable production rules and intelligent demand controller are presented.

• 한국음향학회:학술대회논문집
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• 한국음향학회 1998년도 학술발표대회 논문집 제17권 1호
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• pp.357-360
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• 1998

DS/CDMA system rejected narrow-band interference and additional White Gaussian noise which are occured at multipath, intentional jammer and multiuser to share same bandwidth in mobile communication systems. Because of having not sufficiently obtained processing gain which is related to system performance, they were not effectively suppressed. In this paper, an matched filter channel model using backpropagation neural network based on complex multilayer perceptron is presented for suppressing interference of narrow-band of direct sequence spread spectrum receiver in DS/CDMA mobile communication systems. Recursive least square backpropagation algorithm with backpropagation error is used for fast convergence and better performance in matched filter receiver scheme. According to signal noise ratio and transmission power ratio, computer simulation results show that bit error ratio of matched filter using backpropagation neural network improved than that of RAKE receiver of direct sequence spread spectrum considering of con-channel and narrow-band interference.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2000년도 추계종합학술대회
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• pp.176-179
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• 2000

통신회로에서 많이 사용되는 PLL 방식에 의한 주파수 합성기는 여러 장점이 있지만 위상잡음 특성이 나쁘고 긴 주파수 도약 시간을 갖기 때문에, 최근의 고속(1$\mu\textrm{s}$이하)으로 주파수 호핑(Frequency Hopping)을 요구하는 디지털 통신 시스템에서는 사용이 어렵다. 본 연구는 디지털 영상 패턴 발생기에서 1600hops/s로 600개 이상의 랜덤한 주파수를 발생하는 주파수합성기를 DDS (Direct Digital Synthesis) 방식을 이용하고, CPLD에 의해 구현하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 심포지엄 논문집 정보 및 제어부문
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• pp.78-80
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• 2005

The pattern recognition of automobile and parking line for the automatic car parking system was processed based on statistical method for reducing the processing time. The command of driving for parking at the vacant parking lot was transmitted from processor to motor driven actuator using direct sequence spread spectrum communication, which enables the multiple transmission in CAN(controller area network). The test-bed which has CCD camera, processor, radio transceiver and FPGA was implemented and demonstrated to be operated well.

• International Journal of Internet, Broadcasting and Communication
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• 제7권2호
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• pp.161-167
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• 2015

The performance of high power LEDs highly depends on the junction temperature. Operating at high junction temperature causes elevation of the overall thermal resistance which causes degradation of light intensity and lifetime. Thus, appropriate thermal management is critical for LED packaging. The main goal of this research is to improve thermal resistance by optimizing and comparing nano-pore silicon-based thermal substrate to insulated metal substrate and direct bonded copper thermal substrate. The thermal resistance of the packages are evaluated using computation fluid dynamic approach for 1 W single chip LED module.

• 한국통신학회논문지
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• 제21권4호
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• pp.1077-1088
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• 1996

In this paper, we propose a new method to analyze the performance degradation by timing jitters in the receivers of intensity modulation/direct detection digital optical communication systems where pulse-shaping filters are used to minimize intersymbol interference. The results obtained from the proposed analytical method show that conventional analytical methods underestimate the influence of timing jitters on the receiver performance. Using the proposed anlaytical method, we derive an analytic equation for approximated power penalty due to timing itters and obtain an exact power penalty by numerical analyses. Assuming Gaussian or uniform probability density function for timing jitters, we also show that assumption of Gaussian distribution for timing jitters yields more performance degration than that of uniform distribution.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1987년도 한국자동제어학술회의논문집; 한국과학기술대학, 충남; 16-17 Oct. 1987
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• pp.242-248
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• 1987

Recently, a quite large number of investigation is published on the subject of Flexible Manufacturing System which can cope with the volatile market demand and the variety of product. Minimum requirement of designing FMS is depicted and by investigating the communication system between the machine tool and the cell control computer, ana between the central computer and the cell control computer, when it is formed as a sub-system of an FEM, the software can be evolved to the control software of the total Flexible Manufacturing System. It is developed the communication system between the central computer and the cell control computer which is the basic structure of the control architecture of FMS under the concept of DNC (Direct Numerical Control). It is used CYBER 180-830 as the central computer, and GMC-1100 computer as the cell control computer, and the main basic program is developed and tested, thus forming a DNC system which can be used in educational environment.