• Journal of the Korean earth science society
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• v.42 no.4
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• pp.390-400
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• 2021

Ocean biogeochemistry plays a crucial role in sustaining the marine ecosystem and global carbon cycle. To investigate the oceanic biogeochemical responses to iron parameters in the tropical Pacific, we conducted sensitivity experiments using the Nucleus for European Modelling of the Ocean-Tracers of Ocean Phytoplankton with Allometric Zooplankton (NEMO-TOPAZ) model. Compared to observations, the NEMO-TOPAZ model overestimated the concentrations of chlorophyll and dissolved iron (DFe). The sensitivity tests showed that with increasing (+50%) iron scavenging rates, chlorophyll concentrations in the tropical Pacific were reduced by approximately 16%. The bias in DFe also decreased by approximately 7%; however, the sea surface temperature was not affected. As such, these results can facilitate the development of the model tuning strategy to improve ocean biogeochemical performance using the NEMO-TOPAZ model.

• The Journal of Asian Finance, Economics and Business
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• v.8 no.12
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• pp.75-83
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• 2021

Variation in demand, natural resource availability, and technological advancement within a country are the main reasons for necessitating export and import activities between nations. Accordingly, this paper aims to analyze the effect of economic openness on Multifactor Productivity (MFP) in selected Asian countries (Vietnam, Thailand, The Philippines, Indonesia, Cambodia, China, Japan, Malaysia, South Korea, and Singapore) based on data for the period 1990-2018. The analysis conducted in the study employed the panel ARDL approach based on the estimation by Pooled Mean Group (PMG), Mean Group (MG), and Dynamic Fixed Effect (DFE). The Hausman test conducted indicates that the PMG estimation is better than that of MG and DFE since it has a higher variability value than the significance value. The results revealed that economic openness is able to elicit significant and positive effects on short-term and long-term MFP growth. In addition, the study established that other variable, such as the number of schooling years, are also able to produce a positive and significant effect on MFP growth in the long term. Since economic openness can impact MFP growth, every country should thus increase its export activities through more capital and worker inputs that will stimulate greater production.

• Journal of Nutrition and Health
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• v.40 no.5
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• pp.428-434
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• 2007

Cham-dang-gui (Angelica gigas nakai) has been used in traditional Korean medicine to treat hemotological disorders. The purpose of this study is to investigate the hematological effects of water extracts of Cham-dang-gui in rats with anemia induced by iron-free diets. Rats were divided into two groups, a regular diet group (RD) and an iron-free diet group (FeD). The iron-free diet group was then subdivided into the following three treatment groups: saline (1.0 ml/kgBW/day, FeDS), Cham-dang-gui (1.0 g/kgBW/day, FeDA), and iron (iron succinylate 14 mg/kgBW/day, FeDFe) groups. Rats were fed an iron-free diet for 6 weeks to induce iron-deficient anemia, and subsequently underwent the treatments, during which they were fed an iron-free diet for 3 weeks followed by a regular diet for 3 weeks. Body weights of the iron-diet groups (FeDS, FeDA, FeDFe) were lower than that of RD group. The blood levels of Hgb, Hct, MCV, MCH and TIBC were significantly higher in RD and FeDFe groups than those of other groups. The water extract of Cham-dang-gui with iron-free diet has no hematological effects. A regular diet followed by iron-free diets significantly increased blood levels of Hgb, Hct, and MCH.

• Journal of Broadcast Engineering
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• v.4 no.2
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• pp.103-118
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• 1999

This paper analyzes the performance of symbol timing recovery and equalizer in 8VSB digital terrestrial TV receiver under various multipath signals and proposes equalization techniques which improve indoor reception performance. Data segment sync is used for symbol timing recovery and timing offset is measured for echoes of various delays and amplitudes by using symbol timing detection filter whose pattern is +1. +1. -1. and -1. Measured timing offsets were below 10% for long echoes with more than 5 symbol delay and above 30% for short echoes with around 1 symbol delay. Indoor reception is always more challenging than outdoor reception due to lower signal strength. large and short multipaths. and moving interfering objects. So it is considered to use FSE (Fractionally Spaced Equalizer) which is very robust to timing offset and blind equalizer which can update equalizer tap coefficients even by information data. We compare the performance of conventional DFE (Decision Feedback Equalizer) and FSE-DFE using LMS algorithm and Stop and Go algorithm for the indoor reception. Experiments reveals FSE has excellent performance for large timing offset and Stop and Go algorithm shows good performance for Doppler shift. so we propose to use FSE-DFE structure with Stop and Go algorithm for the reliable indoor reception.

• Journal of Broadcast Engineering
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• v.15 no.1
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• pp.63-75
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• 2010

In this paper, the equalizer techniques that is able to adopt the digital on-channel repeater for 8VSB-based DTV system has been analyzed and we propose an effective equalizer structure which can reduce the error propagation phenomenon by the feedback signal and improve the receiver performance at the same time. In order to confirm the effective cancellation of the feedback signal, the multi-level Correlation LMS scheme is proposed through the analysis of conventional basic LMS based DFE and Correlation LMS algorithm and as compared with the conventional method, we can confirm the reduction of error propagation. When performing the computer simulation, as the Brazil channel model which is very popular for DTV broadcasting system is adopted, the result is drawn by comparing and analysing the equalizer algorithm. We have examine the symbol error rate which is in the range of 15~25dB of operation receipt SNR and MSE(Mean Square Error) in the DTV broadcasting system. As a result of comparing with the existing method, the signal-noise ratio which is necessary for maintain the bit error correction ability that the means of proposal is same is reduced by about 2~5dB, and in the rate of convergence through the MSE, we found the reduction of needed time.

• Information and Communications Magazine
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• v.15 no.12
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• pp.85-96
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• 1998

본 논문에서는 현재 연구 개발되고 있는 HDSL/ADSL 시스템의 동작환경과 채널(선로감쇄(propagation loss), NEXT, 충격잡음 등)에 관하여 언급한 후, 전체 시스템의 구조 및 동작 원리를 기술하였다. 연구 개발된 HDSL/ADSL 전체시스템은 64-CAP 전송방식을 기반으로 Tomlinson precoder, Trellis코드, modulo Viterbi복호기, Convolutional-interleaved R-S 부호기/복호기, Hybrid-DFE, 반향 제거기, 타이밍 복원회로 등으로 구성되어 있다. HDSL/ADSL 전송시스템의 모든 기능들은 디지털로 구현되었으며, 칩 구현을 위하여 각 기능들의 VLSI 시스템 파라메터들을 추출하고 성능시험을 실시하였다.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.32A no.8
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• pp.11-18
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• 1995

This paper proposes a nonlinear adaptive equalizer which is based on fuzzy rules and fuzzy inference of several affine mapping for the received channel data. The proposed nolonlinear adaptive equalizers with the significantly lower computational complexity. Also it can be applied to the on-line adaptation environments owing to its fast convergence characteristics and the lower computational load. When using the decision feedback vectors, this equaalizer can be easily realized in the form of the DFE structure with out the requirement for the perfect channel knowledge as in the case of the fuzzy adaptive filter.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.8B
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• pp.1100-1108
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• 2001

PC-BLRNN을 이용한 무선 비동기 전송 채널 등화기가 본 논문에서 제안되었다. BLRNN은 쌍선형 다항식에 기초한 것으로 MLPNN 형태의 신경망보다 비선형 시스템의 모델링에 탁월한 성능을 보여왔으므로, 매우 비선형적이고 시계열적 특성을 가지는 무선 비동기 전송 채널 등화기에 이용될 수 있다. PC-BLRNN 등화기가 QPSK 신호에 대해 C-DFE, C-MLPNN 등화기 등과 실험적으로 비교되었는데 그 결과, 기존의 등화기들 보다 제안된 PC-BLRNN 등화기가 MSE와 BER의 성능에서 모두 매우 향상된 결과를 보여주었다.

• Proceedings of the Korea Institute of Convergence Signal Processing
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• 2001.06a
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• pp.25-28
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• 2001

A new decision-feedback equalization technique for a filter bank-based orthogonal frequency division multiplexing (OFDM) data transmission system operating in a frequency selective multipath fading channel is presented in this paper. At the cost of relatively increased computational complexity in comparison to the conventional OFDM systems, the proposed system achieves a better performance in terms of bit error rates. The simulation results confirm the superiority and robustness of our method, particularly, in the low SNR channel environment.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.6B
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• pp.625-637
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• 2002

This study extends the modified linear feedback equalizer (MLFE), normally used for differentially coherent DPSK systems, to the equalization of double differentially coherent PSK (DDPSK) signals. By feeding back into the feedback part after modifying the equalizer output using decision feedback-based demodulation, the proposed equalizer can operate like an equalizer with a decision feedback structure. Simulation results showthat performances of the decision feedback demodulation-based feedback equalizer (DFD-FE) approach those of the DFE/coherent.