• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.10
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• pp.2093-2099
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• 2011

Speech signal and car noise signal such as muffler noise are segregated from the one which has both signals mixed using statistical method. To classify speech signal from the other in segregated signals, FFT coefficients were obtained for all segments of a signal where each segment consists of 128 elements of a signal. For several coefficients of FFT corresponding to the low frequencies of a signal, autocovariances are calculated between coefficients of same order of all segments of a signal. Then they were averaged over autocovariances. Linear equation was eatablished for the those autocovariances using the linear regression method for each siganl. The coefficient of the slope of the line gives reference to compare and decide what the speech signal is. It is what this paper proposes. The results show it is very useful.

• Applied Chemistry for Engineering
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• v.10 no.8
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• pp.1099-1103
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• 1999

The surface of an ${\alpha}$-alumina tube was coated with zirconium modified polycarbosilane(PZC) by dip-coating method. Then the tube was pyrolyzed at 573~823 K. The prepared inorganic composite membrane was in $1{\mu}m$ thickness and had no pinholes larger than several nm. For the pyrolyzed inorganic composite membrane, the permeation test of He, $N_2$, $CO_2$, and $O_2$ was performed at 303~423 K. The gas permeation and separation factor were increased with increasing permeation temperature. The permeation for gases was controlled by the activated diffusion mechanism. The separation factor of $CO_2$, to $N_2$was 4.9 at 363 K on the composite membrane pyrolyzed at 823 K and its value was higher than that of He and $O_2$.

• Korean Chemical Engineering Research
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• v.45 no.1
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• pp.81-86
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• 2007

Hollow fiber membrane G-L contactors are widely used to remove $SO_2$ emitted from industrial facilities. In this work, the mathematical modeling and computer simulation for hollow membrane G-L contactors is carried out to analyze $SO_2$ absorption behavior in hollow fiber membranes. The model is solved with the finite element method using a commercial software. Investigated is the dependency of $SO_2$ removal efficiency and mass transfer characteristics on gas velocities, membrane mass transfer coefficients and physical properties of contactors. The membrane mass transfer coefficients are estimated by fitting the experimental data with the simulated $SO_2$ removal efficiencies. In addition, a design methodology of membrane contactors is suggested.

• Proceedings of the Korean Nuclear Society Conference
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• 1996.05c
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• pp.385-390
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• 1996

Cs는 AW500 에서 높은 분배계수 값(K$_{Cs}$>$10^3$$m\ell$/g)을 얻었으며 , Sr은 13X, 평형 용액의 pH=10의 조건에서 최대의 분배계수값(K$_{Sr}$~$10^4$$m\ell$/g)을 보였고, 평형용액의 pH 증가에 따라서 급격히 증가하는 경향을 보였다. 또한 AW500-Cs와 13X-Sr계는 고액비, 즉 V/m=40, 및 초기용액의 pH가 3 이상에서 최대의 분배계수 값을 얻었으며, 혼합제올라이트의 비(AW500/13X)가 1.5인 조건에서 Cs과 Sr을 효과적으로 동시에 분리할 수 있음 보았다. 그리고 1,10$0^{\circ}C$에서 배소한 AW500-Cs는 CsAlSi$_2$O$_{6}$로 재결정되며 , 13X-Sr은 SrAI$_2$Si$_2$O$_{8}$ 및 SiO$_2$상(phase)으로 재결정한다.

• Proceedings of the Membrane Society of Korea Conference
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• 1997.10a
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• pp.51-52
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• 1997

1. 서론 : 폴리이미드는 우수한 기계적 강도와 열적, 화학적 안정성으로 인해 최근 막분리 재료로 많이 연구 검토되고 있다. 대부분의 폴리이미드는 비교적 높은 선택도를 가지고 있으나 투과계수가 떨어지는 단점을 지니고 있어소 이를 극복하기 위한 많은 연구가 진행되어 왔다. 그 결과 투과계수를 크게 증가시킨 폴리이미드를 함성하였으나 선택도는 감소하여 투과특성의 상위한계를 넘지는 못하였다. 이 한계를 극복하기 의해서 복합잴를 이용하거나 UV, 플라즈마 처리에 의한 고분자막의 수식 등 많은 방법들이 연구되고 있다. 본 연구는 NaX형 제올라이트를 폴리이미드에 혼화시킨 막으로 산소/질소의 분리투과특성의 개선을 시도하였으며, NaX형 제올라이트와 폴리이미드 혼화방법, 혼화비율 등이 기체투과특성에 미치는 영향을 고찰하였다. 본 실험에 사용된 NaX형 제올라이트는 직접 합성하여 사용하였다. 폴리이미드는 2,3,5,6-Tetramethyl-1,4-phenylenediamine(p-TeMPD)과 (3,3,4,4'-dicarboxyphenyl)-hexafluoropropene-dianhydride(6FDA)로 합성한 6FDA-p-TeMPD 폴리이미드를 사용하였고, 그 투과계수는 122Barrer, 선택도$\alpha$$_{N_2/O_2}$ = 3.4이다.

• Resources Recycling
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• v.25 no.6
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• pp.50-57
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• 2016

This work was examined the extraction and stripping behavior of rare earths (La, Ce, Pr, Nd, Sm) from the hydrochloric acid solution by Cyanex 572 and compared to the results that of PC88A. Experimental parameters such as equilibrium pH, extractant & strip reagent concentration were observed and extraction percentage, distribution coefficient, stripping percentage and the separation factor of the adjacent element were analyzed. The $pH_{50}$ values was more higher using Cyanex 572 than that of PC88A. As the increase of the extractant concentration, the distribution coefficient of rare earth elements was increased. Stripping percentage of rare earth elementss from the Cyanex 572 was 85% to 95% and PC88A showed 80% to 87%. Separation factor of Ce/La, Ce/Pr, Pr/Nd, Nd/Sm was enhanced about 1.0-5.0 using Cyanex 572 as an extractant in mixture solution.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.2
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• pp.237-245
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• 2012

This paper describes an acoustic echo canceller with double-talk by the blind signal separation. The acoustic echo canceller is deteriorated or diverged in the double-talk period. So we use the blind signal separation to estimate the near-end speech signal and to eliminate the estimated signal from the residual signal. The blind signal separation extracts the near-end signal with dual microphones by the iterative computations using the 2nd order statistical character. Because the mixture model of blind signal separation is multi-channel in the closed reverberation environment, we used the copied coefficients of echo canceller without computing the separation coefficients. By this method, the acoustic echo canceller operates irrespective of double-talking. We verified performances of the proposed acoustic echo canceller by simulations. The results show that the acoustic echo canceller with this algorithm detects the double-talk periods thoroughly, and then operates stably in the normal state without the divergence of coefficients after ending the double-talking. And it shows the ERLE of averagely 20dB higher than the normal LMS algorithm.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1993.10a
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• pp.607-612
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• 1993

원심분리기는 용액 속에 있는 물질을 크기와 밀도 및 모양의 다름을 이용하여 용액으로부터 분리, 정제 및 순화하는 과학기계이며 처리량의 규모에 따라 공업용과 실험실용으로 분류된다. 공업용은 처리량이 많은 반면 실험실용은 처리량이 적으나 분리효과가 좋은 특징을 갖으며 회전속도에 의해 저속, 고속 및 초고속의 원심분리기로 나뉘어진다. 초고속 원심분리기는 최초(30년대)에 침전계수의 측정을 목적으로 연구개발을 시작하였다. 이의 용도에서 사용되는 초고속원심기를 분석용 초고속원심기라 부르나 이는 50년대 이후에 점차적으로 기술적 발전을 가져와 미소물질 분리를 위한 분리용 초고속원심기로 변천이 되어 생물학분야 이외에 항공기,선박,고속철도,석유탐지,원자력,섬유공업과 반도체등 여러 분야에 이용이 되고 있다.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1995.09a
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• pp.211-219
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• 1995

블록-삼각(Block-angular)구조를 갖는 선형 제약식과 분리되지 않는 콘벡스 목적함수의 대규모 비분리 콘벡스 최적화 문제의 해법으로 번들-분해법 (Bundle Based Decomposition)을 이용한 알고리즘 SQA(Separable Quadratic Approximation)은 비분리 콘벡스 프로그램을 분리가능한 2차계획 법(Separable Quadratic Programming) 문제로 근사화시켜 번들-분해법을 축 차적으로 적용한다. 본 연구는 수렴성(local convergence & global convergence) 및 알고리즘 구현 [1]에 이어 이에 대한 수치적용 결과를 중심 으로 소개한다. 수치 적용은 ANSI C로 작성된 SQA 프로그램을 SUN SPARC II에서 실행하였으며 이때 대규모 비분리 최적화 문제의 비분리 목 적함수와 블록-삼각 구조의 선형 제약식들이 계수들은 ANSI C의 랜덤함수 로부터 임의의 값들을 이용하였다. 이와같은 다양한 비분리 콘벡스 최적화 문제에 대한 수렴성, 반복회수 및 처리시간등의 결과와 함께 GAMS/MINOS 의 최적해를 소개한다.

• Resources Recycling
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• v.14 no.6 s.68
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• pp.10-15
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• 2005

In this study, the separation of samarium to neodymium with Karr column was investigated. Separation properties of Sm/Nd binary system was estimated with experimental parameters such as flow rate, initial pH of aqueous phase, saponification of PC88A in organic phase and agitation speed. The extraction rate and distribution coefficient increased with increasing initial pH of aqueous phase at 16.5 ml/min(retention time 10 minute) of flow rate of organic and aqueous phase, and equilibrium pH of aqueous phase after extraction was maintained at 1.5 by saponified PC88A. Also, the extraction rate and distribution coefficient were drastically increased with increasing saponification degree of PC88A and agitation speed, and optimal saponification degree was $40\%$. Extraction rate of Nd and Sm was $19.6\%$ and $72.5\%$ respectively at retention time 10 minute, initial pH 1, saponification degree $40\%$ and agitation speed 120 rpm.