• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년 학술대회 논문집 정보 및 제어부문
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• pp.416-418
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• 2006

In this paper, a new acoustic echo cancellation approach based on the DUET algorithm and scaling factor estimation is proposed to solve the scaling ambiguity in case of blind separation based acoustic echo cancellation in a noisy environment. In hands-free full-duplex communication system. acoustic noises picked up by the microphone are mixed with echo signal. For this reason, the echo cancellation system may provide poor performance. For that purpose, a degenerate unmixing estimation technique, adjusted in the time-frequency domain, is employed to separate undesired echo signals and noises. Also, since scaling and permutation ambiguities have not been solved in the blind source separation algorithm, kurtosis for the desired signal selection and a scaling factor estimation algorithm are utilized in this rarer for the separation of an echo signal. Simulation results demonstrate that the proposed approach yields better echo cancellation and noise reduction performances, compared with conventional methods.

• 한국환경보건학회지
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• 제10권1호
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• pp.87-92
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• 1984

Extraction method of ginseng saponin by Extrelut column was studied as compared with that by phase separation. The results obtained were as follows: 1. Extraction time consumed by Extrelut column was 2 ~ 3 hours and much shorter as compared with that by phase separation. 2. Recovery rates Of ginsenoside by Extrelut column method were 97.8 ~ 106.1% and much higher as compared with those by phase separation method.

• 가정과삶의질연구
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• 제25권1호
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• pp.183-207
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• 2007

The purpose of this study was to improve the understanding of the essential experience of Separated Families in South and North Korea in a socio-cultural context and to explore their post-separation adjustment process from the perspective of the families. Major findings in this study are summarized as follows. First, 'han' was the central phenomenon that the participants experienced following their separation. Second, the core issue in the process of post-separation adjustment was 'accepting the separation and rearrangement of reality for reunion', and over time the participants went through four stages in their adjustment process: the stage of being overwhelmed, the stage of conflict, the stage of awareness, and the stage of acceptance. Third, the main factors affecting the participants' adjustment were supportive systems, available resources(individual variables) and interaction with other separated families. fourth, four types were observed in the typology of adjustment and reunion of the participants.

• 한국해양환경ㆍ에너지학회지
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• 제12권3호
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• pp.197-201
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• 2009

다상유동의 상분리 시뮬레이션 기법으로 Lattice-Boltzmann방법(LBM)을 이용하였다. 기체와 액체상사이의 경계면에서 마이크로한 상호교환을 LBM의 등가함수에서 취급하고 있으며, Van-der-Walls의 free energy를 도입하였다. 표면에너지에 따라 상경계면의 기울기의 변화, 온도에 따른 상분리 특성등을 조사하고, 일정 온도상에서 기체와 액체의 상분리 시뮬레이션을 수행하였다.

• 한국자동차공학회논문집
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• 제10권5호
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• pp.235-241
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• 2002

The process of energy separation in a low pressure vortex tube with air as a working medium is studied In detail. Experimental data of the temperature of the cold and hot air leaving the vortex tube are presented. The variation of the maximum wall temperature along the inner surface of the vortex tube and the temperature distribution in the vortex tube provides useful information about the location of the stagnation point of the flow field at the axis of the vortex tube. In this study Outer tube is used for the application of Diesel engine exhaust. The hot gas flow is fumed 180° and passes the outside of the vortex tube a second time heating it. From this geometric setup of a vortex tube the effects of energy separation and the prediction of the ignition of Diesel Soot is presented by experimental data.

• 한국군사과학기술학회지
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• 제26권4호
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• pp.344-351
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• 2023

Static ejection tests were conducted using the 2,000lb-Class Store to provide ejector model for the store separation simulation. In this study, static ejection test device for 2,000lb-class store was constructed and reaction force applied to store was measured over time. In addition, the trajectories of the ejected store were obtained using photogrammetry and compared with the simulations using developed ejector model. The results of the static ejection test were analyzed to determine the cartridge-orifice combination to be used for store separation. Flight tests were performed by applying the analysis results and verified that the store was safely separated from the aircraft.

• 전기학회논문지
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• 제56권3호
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• pp.629-631
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• 2007

In hands-free full-duplex communication systems, acoustic signals picked up by the microphones can be mixed with echo signals as well as noises, which may result in poor performance of the corresponding communication system. Also, the system performance may decrease further if the reverberation occurs since it is harder to estimate the impulse response of the demixing system. For blind source separation (BSS) in such cases, a time-frequency masking approach can be employed to separate undesired echo signals and noises, but, permutation ambiguities also should be solved for the echo cancellation. In this paper, we propose a new acoustic echo cancellation (AEC) approach utilizing the time-frequency masking and higher-order statistics, whereby a desired signal selection, based on coherence and third-order statistics (i.e., kurtosis), is introduced along with output signal normalization. Simulation results demonstrate that the proposed approach yields better echo and noise cancellation performances than the conventional AEC approaches.

• Structural Engineering and Mechanics
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• 제78권3호
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• pp.369-378
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• 2021

This paper reviewed a few output-only system identification algorithms and identified the shortcomings of those popular blind source separation methods. To address the issues such as less sensors than the targeted modal modes (under-determinate problem), repeated natural frequencies as well as systems with complex mode shapes, this paper proposed a complex wavelet modified second order blind identification method (CWMSOBI) by transforming the time domain problem into time-frequency domain. The wavelet coefficients with different dominant frequencies can be used to address the under-determinate problem, while complex mode shapes are addressed by introducing the complex wavelet transformation. Numerical simulations with both high and low signal-to-noise ratios validate that CWMSOBI can overcome the above-mentioned issues while obtaining more accurate identified results than other blind identification methods.

• 보존과학회지
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• 제25권2호
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• pp.171-178
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• 2009

유구 이전의 안정성은 현재 개발되어 사용되고 있는 반수용성 우레탄 1 차 전사체와 2 차 최종 에폭시 생성물의 우수한 물성으로 볼 때, 박리제의 물성과 박리성에 의해 좌우된다. 본 연구에서는 계면활성제를 사용하지 않은 세 가지 형태의 자기분산형 박리제를 합성하여 이들이 나타내는 박리성과 물성, 박리 후의 상태에 대하여 연구하고자 하였다. 이 수용성 자기 분산형 에폭시의 그 간의 박리제에서 문제시 되었던 지속 기간을 5 시간에서 60 일 이상으로 개선하였으며, 30% 수용화 이상에서 안정한 박리성을 보이고 있고, 건조 전후의 표면 색도의 변화도 없었다. 계면활성화제를 사용한 박리제와 비슷한 결과로 박리압을 나타내어 15~50 kg/$cm^2$을 나타내고 있으며, 저점도의 폴리머 사용 시, 고형분의 함량을 높이더라도 백화 현상이 발생하지 않아 저점도형 박리제로 사용이 가능한 것으로 보인다.

• 한국한의학연구원논문집
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• 제9권2호
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• pp.17-27
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• 2003

Eumyang-ohaeng[陰陽五行-Eumyang and five phases], as a standing rule that establishes the theory of Oriental medicine and origin of the oriental philosophy, it provides the perspective of the oriental medicine's outlook of the world. Without knowing the Eumyang-ohaeng, we cannot discuss Oriental medicine, nor can we understand the oriental way of thinking. Time and Space is what the human being created in order to explain the existence and change of matters. There is a common denominator between this universal concept of time and space and the theory of Eumyang-ohaeng. Consequently this paper investigates how characteristics of Eumyang-ohaeng and that of time and space matches Eumyang represents all matter and its characteristic, by comparison with each other space, and Ohaeng shows the change of matter with time gradually and sequancely. But this separation is only a separation by words, they really melt into one like two sides of a coin is actually just one coin. After all the theory of Eumyang-ohaeng is a theory that leads us to realize time and space, matter and power are all just one. So consequently, despite the difference in mass or size or longevity of matters, Eumyang-ohaeng pulls all matter into one body. It's why Eumyang-ohaeng is defined as the unified theory of time and space.