• The Journal of the Acoustical Society of Korea
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• v.43 no.2
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• pp.253-259
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• 2024

This paper proposes a new speech enhancement model based on a complex nested U-Net with a dual-branch decoder. The proposed model consists of a complex nested U-Net to simultaneously estimate the magnitude and phase components of the speech signal, and the decoder has a dual-branch decoder structure that performs spectral mapping and time-frequency masking in each branch. At this time, compared to the single-branch decoder structure, the dual-branch decoder structure allows noise to be effectively removed while minimizing the loss of speech information. The experiment was conducted on the VoiceBank + DEMAND database, commonly used for speech enhancement model training, and was evaluated through various objective evaluation metrics. As a result of the experiment, the complex nested U-Net-based speech enhancement model using a dual-branch decoder increased the Perceptual Evaluation of Speech Quality (PESQ) score by about 0.13 compared to the baseline, and showed a higher objective evaluation score than recently proposed speech enhancement models.

• Proceedings of the Korea Water Resources Association Conference
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• 2017.05a
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• pp.147-147
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• 2017

본 연구에서는 2003년 태풍 'MAEMI'에 의해 피해를 가장 많이 입은 경남 마산시를 중심으로 폭풍해일 범람도를 작성하였다. 해양과 하천 하류부가 만나는 마산시에서는 해일, 조석, 하천을 동시에 고려해야 하므로 이에 대한 단계적 적용을 통해 범람 중첩효과를 검토하였다. 본 연구에 사용된 수치모델은 네덜란드 Deltares사에서 개발한 준3차원 해수유동 모델 Delft3D이다. Delft3D는 폭풍해일 이외 지진해일, 부유물 이송, 오염물 확산 등 다양한 분야에 적용 가능하며, 파랑, 조석력, 바람에 의한 전단력, 온도, 염도에 의한 밀도류, 대기압 변화, 조간대 모의 등 다양한 영향을 고려할 수 있다. 수치모의시 모델의 안정성과 효율성을 높이기 위해 다중격자기법을 사용(최소 25m 격자)하였으며, 수심 자료는 국토지리정보원 수치지도와 국립해양조사원 수치해도의 수평 수직적 통합을 통해 구성하였다. 태풍 'MAEMI'의 Best Track은 기상청에서 제공하는 3시간 간격의 중심기압, 풍속, 중심위치를 Holland's Model에 적용하여 계산하였다. 조석효과를 고려하기 위해 개방경계에서 TPXO 7.2를 사용한 분조값을 입력하였다. 또한 하천의 흐름을 효과적으로 구현하기 위해 하천 단면에서의 동적 수위경계조건(또는 유량경계조건)을 추가적으로 부여하였다. 수치해석결과, 마산 수위 관측소에서 관측된 태풍 'MAEMI'의 해일고와 유사한 결과가 산출되었다. 범람역 해석결과는 해일, 조석, 하천을 동시적으로 고려하였을 경우에 실제 침수흔적도인 마산시재해침수지도와 가장 유사한 결과를 보였다.

• Journal of Korea Water Resources Association
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• v.37 no.3
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• pp.219-231
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• 2004

The use of air diffuser system to ameliorate the reservoir by breaking stratification is now widespread. This study focuses on the hydrodynamic behavior of bubble plumes, which is the major mechanism of destratification and their combined effect of adjacent plumes on destratification efficiency. By introducing 2-phase Computational Fluid Dynamics(CFD) technique, we could suggest the optimal diffuser spacing having optimal destratification efficiency by simply analyzing the complex destratification procedures varying with the seasonal stratification intensity and bubble flow rate. Lab experiments were also carried out to verify CFD model in thermally stratified fresh water which quite differs from former researches using salts. This study showed that the mixing efficiency strongly depends on the spacing of neighboring plumes. When diffuser spacing is lower than 1.5 times the depth, the combined effect is stronger; as Plume Number(PN) is increased, the efficiency is strongly affected by spacing. If the distance is shorter than the depth of water, the efficiency increases linearly in proportion to PN. Otherwise, the efficiency increases non-linearly. These findings suggest that the combined effect should be more quantitatively taken into consideration for design and operation of air-diffuser destratification system, and recommend that the optimal destratification efficiency will be when plume number is 1000 and the spacing between neighboring diffusers is 1.5 times the depth.

• Korean Journal of Microbiology
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• v.34 no.1_2
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• pp.58-63
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• 1998

Fragment assembly problem is to reconstruct DNA sequence contigs from a collection of fragment sequences. We have developed an efficient X-window program, XFAP, for assembling DNA fragments. In the XFAP, the dimer frequency comparison method is used to quickly eliminate pairs of fragments that can not overlap. This method takes advantage of the difference of dimer frequencies within the minimum acceptable overlap length in each fragment pair. Hirschberg algorithm is applied to compute the maximal-scoring overlapping alignment in linear space. The perfomance of XFAP was tested on a set of DNA fragment sequences extracted from long DNA sequences of GenBank by a fragmentation program and showed a great improvement in execution time, especially as the number of fragments increases.

• Journal of Broadcast Engineering
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• v.21 no.4
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• pp.493-505
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• 2016

Among modern computer vision and video surveillance systems, the pedestrian counting system is a one of important systems in terms of security, scheduling and advertising. In the field of, pedestrian counting remains a variety of challenges such as changes in illumination, partial occlusion, overlap and people detection. During pedestrian counting process, the biggest problem is occlusion effect in crowded environment. Occlusion and overlap must be resolved for accurate people counting. In this paper, we propose a novel pedestrian counting system which improves existing pedestrian tracking method. Unlike existing pedestrian tracking method, proposed method shows that average filter tracking method can improve tracking performance. Also proposed method improves tracking performance through frame compensation and outlier removal. At the same time, we keep various information of tracking objects. The proposed method improves counting accuracy and reduces error rate about S6 dataset and S7 dataset. Also our system provides real time detection at the rate of 80 fps.

• Journal of the Korean Geosynthetics Society
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• v.6 no.3
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• pp.9-16
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• 2007

Soil vapor extraction (SVE) is an effective and cost efficient method of removing volatile organic compounds (VOCs) and petroleum hydrocarbons from unsaturated soils. Incorporating PVDs in an SVE system can extend the effectiveness of SVE to lower permeability soils by shortening the air flow-paths and ultimately expediting contaminant removal. With this approach, the real bounded system is replaced for the purposes of analysis by an imaginary system of infinite areal extent. The boundary conditions for the contaminant remediation model test include constant head and no flow condition. Due to these parallel boundaries conditions, image wells should be developed in order to maintain the condition of no flow across the impermeable boundary. It is also assumed that the flow is drawdown along the constant head boundary condition. The factors contributing to the difference between the theoretical and measured pressure heads were also analyzed. The flow factor increases as the flow rate is increased. The flow rate is the most important factor that affects the difference between the measured and theoretical pressure heads.

• Environmental and Resource Economics Review
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• v.27 no.1
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• pp.29-66
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• 2018

This study constructs an energy-extended KLEM DB of 35 Korean industries, and estimates the elasticities of substitution under various nesting structures of production technologies. Unlike most existing studies that employed only three inputs, K, L, and E, we applied a dual approach where non-energy intermediate input M is also incorporated as a production input. Our dual approach which extended that of van der Werf (2008)'s 3-input model successfully identified and estimated the multi-nested production functions. We provide the estimates of the elasticities of substitution among 4 different energy sources as well. Our estimation results would be used for energy-environment model building for Korea.

• Journal of the Korea institute for structural maintenance and inspection
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• v.20 no.2
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• pp.74-85
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• 2016

Seismic design of modular structures is usually carried out under the assumption that their load-carrying mechanism is similar to that of traditional steel moment-resisting frames(SMRFs). However, the load carry mechanism of modular structures would be different with that of traditional SMRFs because of their overlapped structural elements and complicated details of connections for the assembly of the unit-modules. In this study, nonlinear static analyses of 3 and 5-story prototype modular structures have been carried out with four different analytical models, which are established in consideration for the effects of overlapped elements and the hysteretic behavior of connections. Prototype structures present different lateral stiffness and strength depending on the modeling of overlapped elements and the rotational behavior of connections. For modular structures designed under assumption that overlapped structural elements are fully composite each other and connections between unit-modules are fixed, their lateral strength and stiffness can be over-estimated. Furthermore, it is known from the analysis results that modular structures with more than 3-stories would possess relatively low overstrength compared to traditional SMRFs.

• Korean Journal of Social Welfare Studies
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• v.47 no.4
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• pp.43-69
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• 2016

This study explored whether there are differences in the lives of the poor when they reside in areas with different socioeconomic conditions. Especially the poor living in areas with high poverty are the main focus here, so this study demonstrated their levels of neighborship and mental health. In order to analyze it, 2012 Korean General Society Survey(94 areas, 1,396 individuals) was used and the interaction effect between area poverty and individual poverty was found. As a result, the poor living in deprived areas reported higher social ties with neighbors than the poor living in wealthy areas. Furthermore, double poverty status also increased their psychological well-being level so that it suggested the poor community could be the supportive base for the poor in terms of mental health as well. The meanings of relationships the poor have in poor areas were discussed, and the implications were followed.

• Journal of Astronomy and Space Sciences
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• v.10 no.2
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• pp.146-151
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• 1993

AZ Cas는 B형의 주계열 별과 확장 대기를 가진 만기형으로 이루어진 쌍성계이다. 근성점 근처에서 Roche lobe를 채운 초거성으로부터 일어나는 질량 흐름이 미치는 효과를 구하기 위해 궤도위상 0.05와 0.09에서 불투명도 계수에 따른 AZ Cas의 선윤곽을 계산하였다. 원천 함수는 Hempe(1982)의 방법을 따라 Sobolev 근사방법을 이용하였으며 불투명도 계수가 클수록 넓은 흡수 부분을 가진 강한 선윤곽을 보였다. 궤도 위상 0.05의 부분식이세 나타난 bump는 흡수선위에 포피의 산란에 의해 생긴 방출선이 중첩되어 나타난 재방출 효과인 것으로 설명된다.