• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2012.07a
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• pp.185-187
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• 2012

단일주파수방송망을 이용하여 지상파 3D-HDTV 전송 시 단일주파수방송망에서 발생하는 다중경로채널은 지상파 3D-HDTV 수신성능을 열화시킨다. 최대 다중경로채널의 길이는 단일주파수방송망 내 송신기간 거리에 의해 결정되며, 최소 다중경로 개수는 수신기에 근접한 송신기 개수에 의해 결정된다. 이에 본 논문에서는 다중경로채널의 각 경로 입사각을 추정하기 위한 스마트안테나기반 수신기를 설계하고, beamforming과 nulling 기법 적용 시 지상파 3D-HDTV 수신성능을 분석하였다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39A no.7
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• pp.380-388
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• 2014

Transmission methods for terrestrial UHDTV broadcasting have been actively studied in order to provide enhanced broadcasting service in many countries. Most of the countries are considering multi-carrier transmission methods based on OFDM and some of them have performed UHDTV experimental broadcasting by using the DVB-T2 standard with the adoption of an improved data compression technique. However, since single carrier transmission methods, which are known to be susceptible to multi-path fading, could remedy this defect by using the SC-FDE method where a frequency domain equalizer is utilized in the receiver, they may achieve a similar transmission performance with multi-carrier transmission methods. In consideration of these circumstances, we compare the transmission performances of two-type methods to provide a decision criterion on a suitable transmission method for UHDTV broadcasting.

• Fire Science and Engineering
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• v.34 no.4
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• pp.36-44
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• 2020

It is necessary to predict the activation time of fire detectors accurately to improve the reliability for evaluating the required safe egress time (RSET) in performance-based fire safety design. In this study, problems of the plunge test, which is widely applied in assessing fire detectors, were examined through experiments and numerical simulations. In addition, a new shield-cup test method was proposed to address these problems. A fire detector evaluator (FDE) developed in a previous study was applied to ensure measurement accuracy and reproducibility. During the plunge tests, a significant measurement error was observed in the activation time of the smoke detector because of the rapid flow change when the detector was input. However, during the shield-cup tests, slight changes occurred in the flow inside the FDE when the detector as exposed to smoke. In conclusion, the proposed shield-cup test method is expected to be useful for evaluating the response characteristics of fire detectors more accurately in simulated fire environments.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.48 no.11
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• pp.9-16
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• 2011

We need to establish standard for the ICT based on train control system. In order to solve the ISI problem, this paper evaluate the performance of OFDM and FDE system. We seem that OFDM system is better than FDE system. In order to solve ISI problem, SC System is needed a equalizer. And another method is OFDM System. If system is used SC with a equalizer, It is better than OFDM in terms of PAPR, but this system is not easy to use Multi-Antenna technique, i.e., beam-forming and MIMO-multiplexing. And If system is used high-order modulation, BER performance is worse than OFDM. If we think about in terms of PAPR problem, considerations are considered not significant because the size of relays is not considered in the communication between trains and ground.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.5
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• pp.25-32
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• 2007

This paper proposes a distributed space-frequency block code (SFBC) for relay-assisted single carrier frequency-domain equalization (SC-FDE). The proposed technique achieves spatial diversity gain over fast fading channels without the complexity of multiple antennas. The mobile equipment of the proposed system has a very simple transmitter structure with constant amplitude transmit sequences, which is desirable especially for uplink communications. In order to obtain spatial diversity, the transmit sequence of relay is efficiently generated in the time domain, which is equivalent to the SFBC. Further, efficient implementation of relay and destination structures is also presented. Extensive simulation results show that the proposed system significantly outperforms the distributed space-time block code (D-STBC) SC-FDE over fast fading channels.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.1
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• pp.21-28
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• 2009

DFT-spread OFDM(Discrete Fourier Transform-Spread Orthogonal Frequency Division Multiplexing) is very effective for solving the PAPR(Peak-to-Average Power Ratio) problem. Therefore, the SC-FDMA(Single Carrier-Frequency Division Multiple Access) which is basically same to the DFT spread OFDM was adopted as the uplink standard of the 3GPP LTE ($3^{rd}$ Generation Partnership Project Long Term Evolution). Unlike the ordinary OFDM system, the SC-FDMA using DFT spreading method is vulnerable to the ICI(Inter-Carrier Interference) problem caused by the phase noise and IQ(In-phase/Quadrature) imbalance and effected FDE(Frequency Domain Equalizer). In this paper, the ICI effects from the phase noise and IQ imbalance which can be problems in uplink transmission are analyzed according the back-off level of HPA. Next, we propose the equalizer algorithm to remove the ICI effects. This proposed equalizer based on the FDE can be considered as up-graded and improved version of PNS(Phase Noise Suppression) algorithm. This proposed equalizer effectively compensates the ICI resulting from the phase noise and IQ imbalance. Finally, through the computer simulation, it can be shown that about SNR=14 dB is required for the $BER=10^{-4}$ after ICI compensation when the back-off is 4.5 dB, $\varepsilon=0.005$, $\phi=5^{\circ}$, and $pn=0.06\;rad^2$.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.18 no.4
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• pp.68-72
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• 2004

In this paper, the energy conversion theory of the linear actuator deals with the temperature characteristic analysis with verifying temperature of linear Actuator system This model of linear actuator has winding part and mechanical spring, and a plunger. This paper proposed and experimented the linear Actuator(LA) by using finite difference equation(FDE). The experimental result represented the temperature T1 and T2 which remarks Tl is a center of magnetic road inside of actuator winding part, and T2 is a surface of actuator winding part. And the temperature characteristic of the actuator winding part are experimented by the digital temperature meter TECPEL 322.

• Journal of the Korean Institute of Intelligent Systems
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• v.14 no.4
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• pp.487-492
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• 2004

This paper deals with modeling method and application of Fuzzy Discrete Event System(FDES). FDES have characteristics which Crisp Discrete Event System(CDES) can't deals with and is constituted with the events that is determined by vague and uncertain judgement like biomedical or traffic control. In general, the modeling method of CDES has been studied many times, but that of FDES hasn't been nearly studied by qualitative character and scarcity of applicated system. This paper models traffic system with FDES's character in FTTPN and designs a traffic signal controller.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.11
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• pp.5513-5529
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• 2016

Doppler Effect is a prominent obstacle in vehicular networks, which dramatically increase the Bit-Error-Rate (BER). This problem is accompanied with the presence of the Orthogonal Frequency Division Multiplexing (OFDM) systems in which the Doppler shift interrupts the subcarriers orthogonality. Additionally, Inter-Symbol Interference (ISI) and high Peak-to-Average Power Ratio (PAPR) are likely to occur which corrupt the received signal. In this paper, the single-carrier combined with the frequency domain equalizer (SC-FDE) is utilized as an alternative to the OFDM over the IEEE 802.11p uplink vehicular channels. The Minimum Mean Squared Error (MMSE) and Zero-Forcing (ZF) are employed in order to study the impact of these equalization techniques along with the SC-FDE on the propagation medium. In addition, we aim to enhance the BER, improve the transmitted signal quality and achieve ISI and PAPR mitigation. The proposed schemes are investigated and we found that the MMSE outperforms the ZF equalization under different Doppler shift effects and modulations.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.5A
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• pp.305-310
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• 2012

This paper proposes a selection combined hybrid sequential deconvolution and single carrier modulation with a zero forcing frequency domain equalizer for single carrier transmission system in order to enhance performance. Selection combining method is an algorithm of antenna space diversities, the receiver can choose the best channel environment only with the increase of the number of antennas, but a baseband structure is the same as the traditional receiver architecture. Simulation results show that the proposed algorithm has a better performance rather than the traditional single carrier transmission with a frequency domain equalizer.