• Current Optics and Photonics
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• 제1권4호
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• pp.289-294
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• 2017

A high-performance time-division multiplexing (TDM) -based multiuser (MU) multiple-input multipleoutput (MIMO) system for efficient indoor visible-light communication (VLC) is presented. In this work, a MIMO technique based on RGB light-emitting diodes (LEDs) with selection combining (SC) is utilized for data transmission. That is, the proposed scheme employs RGB LEDs for parallel transmission of user data and transmits MU data in predefined slots of a time frame with a simple and efficient design, to schedule the transmission times for multiple users. Simulation results demonstrate that the proposed scheme offers an approximately 6 dB gain in signal-to-noise ratio (SNR) at a bit error rate (BER) of $3{\times}10^{-5}$, as compared to conventional MU single-input single-output (SISO) systems. Moreover, a data rate of 66.7 Mbps/user at a BER of $10^{-3}$ is achieved for 10 users in indoor VLC environments.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 ITC-CSCC -1
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• pp.66-69
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• 2000

In this paper, we propose a progressive transmission of a video using a 2$\times$2$\times$2 DCT First of all, the video data is transformed into multiresolution represented video data using a 2$\times$2$\times$2 DCT. Then. it is represented by a 3-D EZT(Embedded Zero Tree) coding fur the progressive transmission with a bit-rate scalability. The proposed progressive transmission algorithm needs much less computations and buffer memories than the higher-order convolution based wavelet filter. Also, since the 2$\times$2$\times$2 DCT requires independent local computations, parallel processing can be applied.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 추계학술대회 논문집 학회본부
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• pp.434-436
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• 1996

This paper deals with the signal communication system for MAGLEV which is indispensible to train control with safety and high speed operation. Therefore it is necessary for signal system to ensure high speed transmission. massive transmission, low error rate, and reliability of information. And the ensured information should be transmitted between ground and on-board for safety and high speed operation. For these reasons, we have considered the guaranteed reliability by applying FSK method and HDLC protocol. Because HDLC has the advantages of high efficiency, high reliability, low bit rate, and bit transparency. HDLC is the appropriate method for data transmission in MAGLEV.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권8호
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• pp.3585-3601
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• 2016

The error rate performance of circularly distributed antenna system is studied over Nakagami-m fading channels, where a dual-channel receiver is employed for the quadrature phase shift keying signals detection. To mitigate the Co-Channel Interference (CCI) caused by the adjacent cells and to save the transmit power, this work presents remote antenna unit selection transmission based on the best channel quality and the maximized path-loss, respectively. The commonly used Gaussian and Q-function approximation method in which the CCI and the noise are assumed to be Gaussian distributed fails to depict the precise system performance according to the central limit theory. To this end, this work treats the CCI as a random variable with random variance. Since the in-phase and the quadrature components of the CCI are correlated over Nakagami-m fading channels, the dependency between the in-phase and the quadrature components is also considered for the error rate analysis. For the special case of Rayleigh fading in which the dependency between the in-phase and the quadrature components can be ignored, the closed-form error rate expressions are derived. Numerical results validate the accuracy of the theoretical analysis, and a comparison among different transmission schemes is also performed.

• The Journal of Asian Finance, Economics and Business
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• 제6권3호
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• pp.103-113
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• 2019

The effectiveness of monetary policy critically depends upon how well the transmission mechanism functions, so that the desired impact on output and inflation is achieved. The purpose of this paper is to study the transmission mechanism of monetary policy by analyzing the impact on inflation and output during multiple indicator regime (1998-99 to 2014) in an emerging economy-India. The Inflation Targeting Regime is also briefly outlined alongwith the impact on output and inflation. Using quarterly data for the period 1997 to 2017, the paper uses weighted average call money market rate as a proxy for the policy rate and evaluates the strength of the interest rate channel. We use a conventional Structural vector auto regression (SVAR) methodology to evaluate the efficacy and show the impluse response functions. Our results find that changes in the policy rate impact output growth steeply with a lag of about two quarters and the impact on inflation is maximized after three quarters. The study concludes that the monetary policy in India has a significant impact on output and inflation in the short-to-medium-run. After the policy shock, the fall in the output growth rate is of greater magnitude than the fall in inflation.

• 감성과학
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• 제7권4호
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• pp.67-75
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• 2004

본 논문에서는 ABR(Available Bit Rate) 트래픽의 흐름제어를 방식들을 분석하고, 지연이 큰 PNNI망에서 VS/VD 스위치를 이용하여 효율적으로 ABR 트래픽을 제어하여, 공평한 전송율을 계산할 수 있는 알고리즘을 제안하였다. 제안된 알고리즘에서는 전송률을 계산하기 위하여 정확하고 공평한 분배를 계산할 수 있는 ER(Explicit Rate) 방식의 FMMRA(Fast Max-Min Rate Allocation)를 사용하였다. 그리고, 지연이 많이 된 상태에서도 큐에 있는 셀을 서비스하고 드레인하기 위하여, VD에서 VS로 전달된 큐 길이 정보를 이용하여 전송율을 계산함으로서 공평한 셀 서비스 분배를 할 수 있었다. 컴퓨터 시뮬레이션을 통하여 제안된 알고리즘의 성능을 평가하였으며, 그 결과 만족할 만한 성능을 얻을 수 있었다.

• 한국통신학회논문지
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• 제22권5호
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• pp.939-948
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• 1997

본 논문에서는 ATM 네트워크에서의 접속된 ABR 서비스에 대해 공정한 대역폭을 할당하는 새로운 비율 기반 전송률 제어 알고려즘을 제안한다. 기존 ABR 서비스에서는 일정률로 전송률을 증가, 감소를 하면서 대역폭을 할당하나 제안된 알고리즘에서는 이용 가능한 대역폭을 퍼지 추론을 하여 접속된 호에 대해 전송률을 공평하게 분할하는 기법이다. 퍼지 추론은 입력 변수로 버퍼 상태, 버퍼 변화율을 사용하고 출력 변수로 전체 전송률을 사용한다. 이 추론된 결과값은 동작 중에 있는 ABR 서비스 호에 공평하게 분배되어 진다. 모의 실험 결과 기존의 E EPRCA 방식보다 제안된 방식이 링크 효율면에서 RIF, RDF가 1일 경우 0.17%, 1/4 경우 6%, 1/16 경우 38.6%, 1/32 경우 82.4%의 향상을 보였다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제7권3호
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• pp.446-458
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• 2013

Recently, energy-efficient cellular transmission has received considerable research attention to improve the energy efficiency of wireless communication. In this paper, we consider a cellular network consisting of one base station (BS) and multiple user terminals and explore the network coding for enhancing the energy efficiency of cellular downlink transmission from BS to users. We propose the network coded cellular transmission scheme and conduct its energy consumption analysis with target outage probability and data rate requirements in Rayleigh fading environments. Then, the energy efficiency in Bits-per-Joule is further defined and analyzed to evaluate the number of bits delivered per Joule of energy cost. Numerical results show that the network coded cellular transmission significantly outperforms the traditional cellular transmission in terms of energy efficiency, implying that given a Joule of energy cost, the network coded cellular transmission scheme can deliver more bits than the traditional cellular transmission.

• 전자공학회논문지SC
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• 제45권6호
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• pp.1-9
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• 2008

견마로봇의 통신시스템은 견마로봇이 경계작전을 통해 얻은 멀티미디어 데이터를 지휘국으로 전송하는 상향링크 위주의 시스템으로, 현재의 하향링크 위주의 와이브로 시스템을 견마로봇 통신시스템에 이용하기 위해서는 많은 데이터를 전송하는 상향링크 위주의 전송변수를 갖는 시스템으로 재설계해야 한다. 본 논문은 상향링크에 중점을 둔 견마로봇 시스템에 적합한 전송변수를 결정하였다. WiBre 프레임 내의 슬롯의 개수는 하향링크시 6개 상향링크시 30개로 하였고, AMC, PUSC 전송방식 등을 이용하여 견마로봇의 요구 데이터율을 만족하는 변조율과 부호화율에 맞는 Nep(실효부호패킷의 크기)를 결정하였다. 전산모의실험은 ITU-R. M1225 채널모델을 기반으로 각 전송방식별 Nep와 견마로봇의 이동속도에 따른 전산모의실험을 하였고 설계한 통신변수의 성능분석을 하였다.

• Parasites, Hosts and Diseases
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• 제39권2호
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• pp.185-192
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• 2001

To evaluate the factors that determine the transmission level of vivax malaria using vectorial capacity, entomological surveys were conducted from .lune to August, 2000. From 6 nights of human-bait collection in Paju, the human biting rate (ma) was counted as 87.5 bites/man/night. The parity of Anopheles sinensis from human baiting collections fluctuated from 41% to 71% (average 48.8%) of which the rate gradually increased as time passed on: 35.2% in Jun. ; 55.0% in July; 66.2% in Aug. From this proportion of parous, we could estimate the probability of daily survival rate of An. sinensis to be 0.79 assumed with 3 days gonotrophic cycle and the expectancy of infective life through 11 days could be defined as 0.073. Blood meal analysis was performed using ELISA to determine the blood meal source. Only 0.8% of blood meals were from human hosts. We could conclude that An. sinensis is highly zoophilic (cow 61.8%) Malaria is highly unstable (stability index < 0.5) in this area. From these data, vectorial capacity VC) was determined to be 0.081. In spite of a high human biting rate (ma), malaria transmission potential is very low due to a low human blood index. Therefore, we could conclude that malaria transmission by An. sinensis is resulted by high population density, not by high transmission potential. For this reason, we need more effort to decrease vector population and vector-human contact to eradicate malaria in Korea.