• Journal of the Korean Institute of Telematics and Electronics D
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• v.35D no.11
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• pp.10-22
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• 1998

In this paper, as a way of improving the availability and spectral efficiency of radio relay system, a co-channel radio relay system based upon the synchronous digital hierarchy is developed and its performance measured by 64-QAM with a never-seen multi-purpose ASIC chip is illustrated. This system provides a couple of transmission capacity compared with alternative channel arrangement. By adopting a powerful complex 13-tap adaptive time domain equalizer and cross-pol interference canceller, improvement of more than 1.5 ~ 2.0 dB in signature is obtained in comparison to 9 or 11-tap adaptive time domain equalizer, and about 22.5 dB in improvement factor of cross-pol interference canceller is achieved at C/N of 24.5 dB. In addition, digital filter makes it possible to optimize the occupied bandwidth by selecting an appropriate roll-off factor externally. It is expected that co-channel radio relay system with the powerful multi-purpose ASIC chip plays a key role in creating a value-added product, reliability, and reducing the outage time.

• Journal of the Korean Society of Safety
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• v.29 no.6
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• pp.166-171
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• 2014

Nuclear power plants are equipped with the reactor trip system (RTS) and the engineered safety features actuation system (ESFAS) to improve safety on the normal operation. In the event of the design basis accident (DBA), a various of post accident monitor(PAM)systems support to provide important details (e.g. Containment pressure, temperature and pressure of reactor cooling system and core exit temperature) to determine action of main control room (MCR). Operator should be immediately activated for the accident mitigation with the information. Especially, core exit temperature is a critical parameter because the operating mode converts from normal mode to emergency mode when the temperature of core exit reaches $649^{\circ}C$. In this study, uncertainty which was caused by exterior environment, characteristic of thermocouple/connector and accuracy of calibrator/indicator was evaluated in accordance with ANSI-ISA 67.04. The square root of the sum of square (SRSS) methodology for combining uncertainty terms that are random and independent was used in the synthesis. Every uncertainty that may exist in the hardware which is used to measure the core exit temperature was conservatively applied and the associative relation between the elements of uncertainty was considered simultaneously. As a result of uncertainty evaluation, the channel statistical allowance (CSA) of single channel of core exit temperature was +1.042%Span. The range of uncertainty, -0.35%Span ($-4.05^{\circ}C$) ~ +2.08%Span($24.25^{\circ}C$), was obtained as the operating criteria of core exit temperature.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.2B
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• pp.170-177
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• 2009

In this paper, we propose the structures of the NBTC (Narrow-Beam Trisector Cell) and the WBTC(Wide-Beam Trisector Cell) in which directional antennas both at the base station and at the relay station are used. We analyze and compare total capacity of the both systems taking the co-channel interference into consideration for two channel models. Through analysis, we find the effect of LOS (Lind of Sight) path to the total capacity of NBTC structure and that of WBTC structure. Our work may be useful as a guideline to control the interference for the next generation mobile communication and WiBro systems using multi-hop relays.

• Journal of Broadcast Engineering
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• v.5 no.2
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• pp.199-210
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• 2000

The IBAC (In-Band Adjacent-Channel) DAB (Digital Audio Broadcasting) system is to provide multichannel CD quality audio services and multimedia data services including text and picture in FM band (88~105 MHz). As the FM band is being used by the existing analog radio broadcasting, there must he an analysis of the interference effect between IBAC DAB and analog FM signal. Therefore, the protection ratio should be evaluated to verify the system compatibility and allocate the new IBAC DAB channel in FM band. In this paper, among the three types of interferences, FM-to-DAB, DAB-to-FM and DAB-to-DAB, that can be occurred, the Protection ratio of IBAC DAB system for co-channel FM interferer is analyzed by modeling the FM interferer and considering the multipath fading channel. The simulation results show that IBAC DAB system has far better sensitivity than Eureka 147 and needs a relatively high protection ratio for co-channel FM interferer, because of its narrow bandwidth, about one third of that of Eureka 147.

• Bulletin of the Korean Space Science Society
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• 2011.04a
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• pp.30.2-30.2
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• 2011

In this report, we present in-orbit radiometric performance prediction for the Amon-Ra (Albedo Monitor and Radiometer) energy channel instrument. The Integrated Ray Tracing (IRT) computational technique uses the ray sets arriving at the Amon-Ra instrument aperture orbiting around the L1 halo orbit. Using this, the variation of flux arriving at the energy channel detector was obtained when the Amon-Ra instrument including the energy channel design observes the Sun and Earth alternately. The flux detectability was verified at the energy channel detector (LME-500-A, InfraTecTM). The detector time response and RMS signal voltage were then derived from the simulated flux variation results. The computation results demonstrate that the designed energy channel optical system satisfies the in-orbit detectability requirement. The technical details of energy channel instrument design, IRT model construction, radiative transfer simulation and output signal computation results are presented together with future development plan.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.1
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• pp.85-90
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• 2006

This paper presents experimental results relating to the preliminary breakdown characteristics in $SF_6/CO_2$ gas mixtures under a highly non-uniform electric field. The impulse pre-breakdown developments are investigated by the measurements of corona current and light emission images. As a result, the preliminary breakdown development mechanisms for both the positive and negative polarities were fundamentally same. The first streamer corona was initiated at the tip of needle electrode, and the leaders developed with a stepwise propagation and bridged the test gap. The pause time of leader pulses in the positive polarity was significantly shorter than that in the negative polarity. Also, the time interval between the first streamer corona onset and breakdown in the negative polarity was much longer than that in the positive polarity. The discharge channel path in the positive polarity was zigzag, and the leader channel in the negative polarity was thicker and brighter than that in the positive polarity.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.11 s.102
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• pp.1138-1146
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• 2005

This paper makes a study of a formulation of net filter discrimination(NFD) and its computation for analyzing adjacent channel interference and suggests a systematic algorithm for calculating protection ratios of co-channel and adjacent channel applicable to frequency coordination in the fixed radio relay networks. It is shown that adjacent channel protection ratio can be derived from two factors: One is NFD depending upon receiver filter characteristic as well as transmitter spectrum mask and the other is co-channel protection ratio given by a function of fade margin, modulation scheme, and allowable interference. Actually to show the computing procedure from transmitter spectrum mask and receiver filter characteristic, NFD has been obtained for channel bandwidth of 29.65 and 40 MHz at 6.2 and 6.7 GHz band, respectively. According to the results, NFDs at the first adjacent channel of 29.65 and 40 MHz provide 27.4 and 28.9 dB, respectively. From these data, adjacent channel protection ratios corresponding to each channel bandwidth yield 47.5 and 46.3 dB for a given 64-QAM and 60 km. The proposed method gives some merits of an easy calculation, systematic extension, and applying the same concept to frequency coordination in millimeter radio relay networks.

• Journal of Advanced Navigation Technology
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• v.15 no.2
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• pp.213-220
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• 2011

In this paper, the channel preprocessor with an area-efficient architecture is proposed for the MIMO symbol detector which can support four transmit and receive antennas. The proposed channel preprocessor can shrink the channel dimension to reduce the hardware complexity of the MIMO symbol detector. Also, the proposed channel preprocessor is implemented with very low complexity by using QR decomposition (QRD) and log-number system (LNS). By applying QRD and LNS to the nulling matrix calculation block, the numbers of matrix-multiplications and matrix-divisions are decreased and thus the complexity of the proposed channel preprocessor is significantly reduced. The proposed channel preprocessor was designed in a hardware description language (HDL) and synthesized to gate-level circuits using 0.13um CMOS standard cell library. With the proposed channel preprocessor, the number of logic gates for channel preprocessor is reduced by 20.2% compared with the conventional architecture.

• The Plant Pathology Journal
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• v.32 no.3
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• pp.242-250
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• 2016

The aim of this study was to investigate antifungal activity of a range of different molecular weight (MW) chitosan against Penicillium italicum. Our results demonstrate that the antifungal activity was dependent both the MW and concentration of the chitosan. Among a series of chitosan derived from the hydrolysis of high MW chitosan, the fractions containing various sizes of chitosan ranging from 3 to 15 glucosamine units named as chitooligomers-F2 (CO-F2) was found to show the highest antifungal activity against P. italicum. Furthermore, the effect of CO-F2 toward this fungus was significantly reduced in the presence of $Ca^{2+}$, whereas its effect was recovered by ethylenediaminetetraacetic acid, suggesting that the CO-F2 acts via disruption of $Ca^{2+}$ gradient required for survival of the fungus. Our results suggest that CO-F2 may serve as potential compounds to develop alternatives to synthetic fungicides for the control of the postharvest diseases.

• Journal of the Institute of Convergence Signal Processing
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• v.20 no.4
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• pp.177-185
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• 2019

In this paper, we propose and evaluate a FDE combined with STBC transmission structure to cancellation of ISI in underwater acoustic communication. To achieve this purpose, underwater acoustic channels are modeled and the simulation results are presented. In case of STBC-FDE, the transmission rate is less about 4% than STBC-OFDM, but the SER performance is better than STBC-OFDM that is larger from 4.4% to 16.8% at the SNR of 15dB than STBC-OFDM.