• KSCE Journal of Civil and Environmental Engineering Research
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• v.43 no.3
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• pp.321-335
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• 2023

Monitoring sediment loads in natural rivers is the key process in river engineering, but it is costly and dangerous. In practice, suspended loads are directly measured, and total loads, which is a summation of suspended loads and bed loads, are estimated. This study proposes a real-time sediment discharge monitoring system using the horizontal acoustic Doppler current profiler (H-ADCP) and support vector regression (SVR). The proposed system is comprised of the SVR model for suspended sediment concentration (SVR-SSC) and for total loads (SVR-Q_TL), respectively. SVR-SSC estimates SSC and SVR-Q_TL mimics the modified Einstein procedure. The grid search with K-fold cross validation (Grid-CV) and the recursive feature elimination (RFE) were employed to determine SVR's hyperparameters and input variables. The two SVR models showed reasonable cross-validation scores (R²) with 0.885 (SVR-SSC) and 0.860 (SVR-Q_TL). During the time-series sediment load monitoring period, we successfully detected various sediment transport phenomena in natural streams, such as hysteresis loops and sensitive sediment fluctuations. The newly proposed sediment monitoring system depends only on the gauged features by H-ADCP without additional assumptions in hydraulic variables (e.g., friction slope and suspended sediment size distribution). This method can be applied to any ADCP-installed discharge monitoring station economically and is expected to enhance temporal resolution in sediment monitoring.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2020.11a
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• pp.140-142
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• 2020

본 논문에서는 심층적 강화학습 기반 GOP (Group of Picture) 크기를 선택하여 HEVC/H.265의 인코더를 제어하는 방법을 제안한다. 기존 방법에서는 현재 비디오 신호를 부호화 하는 과정에서 이미 부호화한 정보를 사용해야하는 부호화 의존성에 관한 문제가 있었다. 제안 방법은 강화학습 방식을 도입하여 이러한 문제를 극복하고 입력 비디오의 시간적 상관도에 따라 GOP의 크기를 적응적으로 선택하여 부호화 한다. 본 논문에서는 GOP 선택을 위한 강화학습 환경을 새롭게 정의하고 부호화 성능에 따른 보상을 부여하는 방식으로 학습을 수행한다. 제안된 적응적 GOP 선택에 따라 인코더 제어 시, 부호화 방법의 부호화 효율이 -6.07% BD-rate 향상된 실험 결과를 보이며 본 방법의 우수성을 입증한다.

• KSBB Journal
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• v.15 no.2
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• pp.174-180
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• 2000

Pichia pastoris and Hansenula polymorpha, the methylotrophic yeasts have been widely used as a host for the production of e eudaryotic proteins due to the advantages related to their inherited characters. This paper describes the method to enhance t the productivity of recombinant proteins by P. pastoris and H. po$\psi$morpha. In the production of recombinant proteins using a f fed batch fermentation system, the effects of specific growth rate on the specific expression rate of re$\infty$mbinant proteins w were studied. In both species, the expression system of recombinant proteins using the fed batch fermentation was optimezed.

• Journal of Food Hygiene and Safety
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• v.34 no.1
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• pp.106-114
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• 2019

The effect of physical and chemical treatments to reduce staphylococcal phages was investigated. To determine impact of physical treatment on viability of phages, two staphylococcal phages (SAP84 and SAP89) were treated with multiple heat ($55^{\circ}C$ and $60^{\circ}C$) and pH (pH4, 7, 10) conditions. Viability of SAP 84 was dramatically reduced at 60C and SAP 89 was completely inactivated at 60C within 25 min. Overall, the two phages were stable under all the pH conditions tested except for the SAP 89 at pH 10. Treatments, a 10% FAS (Ferrous Ammonium Sulfate) solution and various density of ethanol and sodium hypochlorite were used to reduce the two phages. SAP 84 was unstable in 50% and 70% ethanol. However, SAP 84 and SAP 89 showed high tolerance after exposure to 100 ppm of sodium hypochlorite which is known as an effective sterilizer. As soon as the two phages were treated with 10% FAS, which is used as a virucidal agent, they were inactivated and did not form any plaque. The result of this study provides additional evidence that staphylococcal phages can be controlled by various physicochemical treatments.

• The Journal of the Korea Contents Association
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• v.9 no.4
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• pp.12-18
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• 2009

In this paper, we propose a novel method which efficiently codes $4{\times}4$ intra prediction modes in H.264/ AVC video encoding. There are nine optional prediction modes for each $4{\times}4$luma block and 4 modes for each $16{\times}16$luma block. To code each $4{\times}4$ intra prediction mode, lots of bits are required. To efficiently compress the intra mode bits in H.264/AVC, the most probable mode(MPM) is estimated by using the intra modes of the adjacent blocks, since intra modes for neighboring $4{\times}4$luma blocks are correlated. In this paper, a novel method for estimating the MPM is proposed by using the statistical distribution of intra modes of adjacent intra blocks. Experimental results show that the proposed method can achieve a coding gain of about 0.1dB.

• The KIPS Transactions:PartB
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• v.13B no.3 s.106
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• pp.197-204
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• 2006

Recent advances in information technology have resulted in rapid growth in the mobile communication. With this explosive growth, reliable transmission and error concealment technique become increasingly important to offer high quality multimedia services. In this paper, we propose an improved BMA(Boundary Matching Algorithm) method using gradient vectors to conceal channel errors in inter-frames of H.264 video images. General BMA method computes the sum of pixel differences of adjacent pixels of the candidate block and its neighbouring blocks, assuming that adjacent pixels have almost the same value. In real images, however, there exist some gradients, which means that the pixel values are increasing or decreasing in a specific direction. In this paper, we develop a precise estimation method of errors in candidates blocks using gradient information and try to recover lost blocks with this technique. Experimental results show the improvement of picture quality about $1{\sim}3dB$ compared to existing methods.

• Proceedings of the Korean Information Science Society Conference
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• 2001.10b
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• pp.403-405
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• 2001

한정된 대역폭의 통신망에서 다른 매체에 비해 자료량이 많은 화상의 압축은 중요한 문제로 떠올랐다. 대표적인 영상 압축방법으로 MPEG 시리즈와 H.26x 시리즈가 있다. 그중 H.263은 화상회의 표준안인 H.323와 최근 진행중인 차세대 이동통신이라 일컬어지는 IMT-2000에서 영상압축방법중의 하나로 채택되었다. 또한 현대에 이르러 Desktop상에서의 영상회의구축은 더 이상 불가능한 일이 아니며, 또 하나의 영상회의 활용분야로 급속히 떠오르고 있다. 이는 internet의 보급과 함께 internet방송, 다대다 화상회의, 원격 의료 진료 등, 수없이 많은 분야에 활용될 수 있는 계기가 마련되었다. 이에 본 논문에서는 H.261과 H.263, 그리고 H.263 version 2의 Desktop상에서의 실제적인 구현 및 비교를 기술한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.8C
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• pp.1055-1061
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• 2004

In this paper, we propose an efficient dynamic coding scheme by using multiple codewords in H.264/AVC entropy coding. The exponential Golomb (Exp-Golomb) codewords used in H.264/AVC do not reflect enough the symbol distributions of the combined syntax element in (7) due to their static probability distribution characteristics. However, the multiple codewords in this paper have different statistical characteristics. we propose a dynamic coding scheme by using selectively among multiple codewords to encode the combined syntax element according to given image sequences. Simulation results show that our proposed scheme outperforms the existing (7) method in compression efficiency without loss of quality.

• Journal of Broadcast Engineering
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• v.15 no.2
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• pp.280-289
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• 2010

The H.264/AVC standard uses efficient inter prediction technologies improving the coding efficiency by reducing temporal redundancy between images. However, since H.264/AVC does not efficiently encode a video sequence that occurs a local illumination change, the coding efficiency of H.264/AVC is decreased when a local illumination change happens in video. In this paper, we propose an improved motion compensation using adjacent pixels and motion vector refinement to efficiently encode local illumination changes. The proposed method always improves the BD-PSNR (Bj$\o$ntegaard Delta Peak Signal-to-Noise Ratio) of 0.01 ~ 0.21 dB compared with H.264/AVC.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.9C
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• pp.1244-1251
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• 2004

In this paper, we propose an efficient dynamic coding scheme by using multiple code words in H.264/A VC entropy coding. The exponential Golomb (Exp-Golomb) code words used in H 264/A VC do not reflect enough the symbol distributions of the combined syntax element in [7] due to their static probability distribution characteristics However, the multiple codewords in this paper have different statistical characteristics. we propose a dynamic coding scheme by using selectively among multiple codewords to encode the combined syntax clement according to given image sequences. Simulation results show that our proposed scheme outperforms the existing [7] me in compression efficiency without loss of quality.