• Journal of Broadcast Engineering
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• v.25 no.3
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• pp.338-345
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• 2020

Versatile Video Coding (VVC), which has been developing as a next generation video coding standard, has adopted various techniques to achieve more than twice the compression performance of HEVC (High Efficiency Video Coding). The recently released VVC Test Model (VTM) shows 38% Bjontegaard Delta bitrate (BD-rate) improvement and 9x/1.6x encoding/decoding complexity over HEVC. In order to reduce such increased complexity, various fast algorithms have been proposed. In this paper, gradient-based methods of fast intra mode decision and block splitting are presented. Experimental results show that, compared to VTM6.0, the proposed method gives up to 65% encoding time reduction with 3.54% BD-rate loss in All-Intra (AI) configuration.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.14 no.1
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• pp.1-6
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• 2014

Recently, orthogonal frequency-division multiplexing(OFDM), with clusters of subcarriers allocated to different subscribers(often referred to as OFDMA), has gained much attention for its ability in enabling multiple-access wireless multimedia communications. In such systems, carrier frequency offsets (CFOs) can destroy the orthogonality among subcarriers. And the mismatch in sampling frequencies between transmitter and receiver can lead to serious degradation due to the loss of orthogonality between the subcarriers. As a result, multiuser interference (MUI) along with significant performance degradation can be induced. In this paper, we present a scheme to compensate for the SFOs and CFOs at the base station of an OFDMA system. A novel sampling frequency offset estimation algorithm is proposed, which is based on the repetition of a symbol at the communication start-up. Then, circular convolutions are employed to generate the interference after the discrete Fourier transform processing, which is then removed from the original received signal to increase the signal to interference power ratio(SIR). Simulation result shows that the proposed scheme can improve system performance.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.5
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• pp.112-120
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• 2013

In this paper, we propose high-performance H.264/AVC CAVLC encoder for UD video real time processing. Statistical values are obtained in one cycle through the parallel arithmetic and logical operations, using non-zero bit stream which represents zero coefficient or non-zero coefficient. To encode codeword per one cycle, we remove recursive operation in level encoding through parallel comparison for coefficient and escape value. In oder to implement high-speed circuit, proposed CAVLC encoder is designed in two-stage {statical scan, codeword encoding} pipeline. Reducing the encoding table, the arithmetic unit is used to encode non-coefficient and to calculate the codeword. The proposed architecture was simulated in 0.13um standard cell library. The gate count is 33.4Kgates. The architecture can support Ultra Definition Video ($3840{\times}2160$) at 100 frames per second by running at 100MHz.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.9
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• pp.1023-1029
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• 2007

In this paper, we propose the method to solve the BLT equations using Laguerre polynomials in time domain. The solution of BLT equations is obtained by recursive, differential and integral properties of Laguerre polynomials. The verification of the proposed method is tested by applying it to the two-wired transmission line with resistors and capacitors, which is illuminated by the electromagnetic plane wave pulse. And the result is compared with the corresponding transient responses obtained from inverse fast Fourier transform(IFFT) of the frequency domain solutions of BLT equations.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.1C
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• pp.81-89
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• 2009

We propose a D-ATR UWB (Differential-Average Transmitted Reference Ultra Wide Band) system based on impulse radio. The TR-UWB systems including traditional TR (Transmitted Reference) and ATR (Average TR), exhibit a problem of reduced data rate, since reference signals are additionally transmitted. To tackle this issue, the transmitter of the proposed D-ATR system employs a differential coding like the conventional D-TR system. In addition, the receiver of the proposed system has the structure that can improve signal-to-noise ratio of the reference template used in the correlation process, by recursively averaging the received reference signals like the conventional ATR system. The simulation results in the IEEE 802.15.4a UWB multipath channel models reveal that the proposed D-ATR system achieves much better bit error rate performance as compared to the conventional D- TR system.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.4B
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• pp.394-402
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• 2009

In this paper, we present a new analytical model for estimating the blocking performance of multi-fiber WDM networt:s with sparse and limited wavelength conversion (SLWC). The proposed model is a reduced-load approximation model that can obtain accurate estimates of blocking probability of such networks. Our model employs three new recurrence formulae to obtain the free wavelength distribution on a multi-fiber link, the free wavelength distribution after limited-range wavelength conversion and the end-to-end blocking probability of a multi-hop path, respectively. From the numerical results on the NSFNET, we demonstrate that the blocking performance of two-fiber NSFNET with three wavelength-convertible nodes, each of which translates an input wavelength to its adjacent output wavelengths, closely approximates the blocking performance of full wavelength conversion.

• Korean Journal of Social Welfare Studies
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• no.36
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• pp.253-280
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• 2008

Previous research indicates that depressive symptoms and alcohol consumption are highly correlated with each other. However, there is lack of consensus on the causal relationship between depressive symptoms and alcohol use. In order to address this limitation, this paper examines causal relationship between the two variables using non-recursive structural equation modeling, controlling sociodemographic and psycho-socio-behavioral variables. Data included 14,469 community dwelling individuals who participated in Korea Welfare Panel Study in 2006. Results showed that the effects of alcohol consumption on depressive symptoms was statistically significant, whereas the effects of depressive symptoms on alcohol consumption was not. Significant portions of the effects of psycho-socio-behavioral variables on depressive symptoms were indirect through their effects on alcohol consumption. Based on the results, implications for intervention and future research were discussed.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.24 no.3
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• pp.349-354
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• 2020

The preliminary investigation to expand the green space requires a lot of cost and time. In this paper, we solve the problem by measuring the ratio of green space in a specific region through a convolutional neural network based the green space classification using Google Earth images. First, the proposed method collects various region images in Google Earth and learns them by using the convolutional neural network. The proposed method divides the image recursively to measure the green space ratio of the specific region, and it determines whether the divided image is green space using a trained convolutional neural network model, and then the green space ratio is calculated using the regions determined as the green space. Experimental results show that the proposed method shows high performance in measuring green space ratios in various regions.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.12
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• pp.1926-1933
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• 2022

Parameterized multichannel Wiener filter (PMWF) is a linear filter that can control the trade-off between residual noise and signal distortion using the embedded parameter. To apply the PMWF to noisy inputs, accurate noise estimation is important and multichannel minima-controlled recursive averaging (MMCRA) is widely used. However, in the case of the MMCRA, the accuracy of noise estimation decreases when a directional interference is involved into the array inputs. Consequently, the performance of the PMWF is degraded. Therefore, we propose a noise power spectral density (PSD) estimation method for the PMWF in this paper. The proposed method is based on a consecutive process of eigenvalue decomposition on noisy input PSD, estimation of the target component contribution using directional information, and exponential weighting for improved estimation of the target contribution. For evaluation, four objective measures were compared with the MMCRA and we verify that the PMWF with the proposed noise estimation method can improve performance in environments where directional interfereces exist.

• Journal of KIISE:Software and Applications
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• v.27 no.10
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• pp.1062-1071
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• 2000

한국어의 기반 명사구, 즉 비재귀적인 단순 명사구를 인식하는 비통계적인 규칙 기반 학습 기법을 제안한다. 학습 말뭉치에 기반 명사구에 대한 초기 예측이 표시되어 있고 목표 말뭉치에는 올바른 기반 명사구가 태그(tag)의 형식으로 표시되어 있다면, 규칙 기반 학습은 먼저 인접한 주위 형태소들의 다양한 문법적 정보를 나타내는 규칙 템플릿을 이용하여 기반 명사구 태그를 수정하는 규칙 후보들을 생성해 내고, 이 후보들 가운데 학습 말뭉치를 목표 말뭉치에 가장 가깝게 변환하는 일련의 규칙들을 차례로 얻어낸다. 국어정보베이스의 15만 단어 규모의 트리 태그 부착 말뭉치를 이용한 실험 결과 386개의 변환 규칙을 얻었으며, 이를 이용하여 90% 이상의 높은 기반 명사구 인식 정확도를 얻을 수 있다.