• Journal of the Korean Geosynthetics Society
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• v.18 no.2
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• pp.1-10
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• 2019

This study was intended to evaluate the water permeability and structure for calcium bentonite-sand mixtures to utilize calcium bentonite as a liner. This study conducted physico-chemical properties tests, compaction tests, permeability test and Scanning Electron Microscopy analysis (SEM) analysis. It was found the higher the ratio of calcium bentonite, the lower the dry density with coefficient of permeability, and the higher the optimum moisture content. In particular, SEM analysis was found the higher the ratio of calcium bentonite, the higher the area of the montmorillonite particles. In conclusion, the optimum coefficient of permeability that finds the landfill liner condition (must be less than $1{\times}10^{-7}cm/sec$) was obtained when the ratio of calcium bentonite was 40% or higher. These findings may improve the understanding of the calcium bentonite as a liner. Calcium bentonite shows a similar permeability to sodium bentonite 7% when mixed at 40% or more. Therefore, it is considered that calcium bentonite can be utilized as a liner.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.41 no.1
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• pp.48-53
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• 2013

Polynomial response surface model has been widely used as approximation model which replace physical or numerical experiments in various engineering fields. Generally, low-order model is used to reduce experimental points required to construct the response surfaces, but this approach has limit to represent the highly non-linear phenomena. In this paper, we developed the method to expand modeling capabilities of polynomial response surfaces by increasing order of polynomial and selecting optimum polynomial basis functions. Genetic algorithm is used to choose optimal polynomial basis functions. Developed method was applied to analytic functions with 1 or 2 variables and wind tunnel test data modeling. The results show that this method is applicable to building response surface models for highly non-linear phenomena.

• Journal of Wetlands Research
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• v.13 no.3
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• pp.385-394
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• 2011

In this study, optimal parameters of diffusion-analogy GIUH were calculated by separating channel and hillslope from drainage structures in the basin. Parameters of the model were composed of channel and hillslope, each velocity($u_c$, $u_h$) and diffusion coefficient($D_c$, $D_h$). Tanbu subwatershed in Bocheong river basin as a target basin was classified as 4th rivers by Strahler's ordering scheme. The optimization technique was applied to the SCE-UA, the estimated optimal parameters are as follows. $u_c$ : 0.589 m/s, $u_h$ : 0.021 m/s, $D_c$ : $34.469m^2/s$, $D_h$ : $0.1333m^2/s$. As a verification for the estimated parameters, the error of average peak flow was about 11 % and the error of peaktime was 0.3 hr. By examining the variability of parameters, the channel diffusion coefficient didn't have significant effect on hydrological response function. by considering these results, the model is expected to be simplified in the future.

• Proceedings of the Acoustical Society of Korea Conference
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• 1993.06a
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• pp.75-79
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• 1993

본 논문에서는 변화가 심한 음원파형을 추정하는 새로운 순차처리 알고리듬을 제안한다. 먼저, 1) 기존의 순차처리 분석법중 대표적인 분석법인 RLS(recursive least square)의 문제점들을 검토하고, 2) 이를 개선하기 위해서 관측행렬(observation matrix)을 최적차수의 SVD(reduced-rank singular value decomposition)로 재구성하고, 3) 이에 견실개념(robustness concept)을 적용해서 최적의 성도변수(vocal tract parameter)를 찾아내고 역필터를 적용해서 음원(voice source)을 효과적으로 구분해낸다. 본 논문에서 제안된 방법으로 음원을 추정할 경우, 변화가 심한 음원파형을 잘 추정할 수 있으며, 음원의 특성을 구분해낸 성도 파라미터도 효과적으로 추정할 수 있다. 본 연구내용은 음성합성에서 자연성 개선 및 개인성 구현을 위해서 필수적이며, 다양한 형태의 음성을 표현하기 위해 사용되어질 수 있다. 또한, 음성코딩, 화자인식, 음성인식에서도 사용되어질 수 있다.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2004.10a
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• pp.429-432
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• 2004

본 논문은 기존의 퍼지 다항식 뉴럴 네트워크 (Fuzzy Polynomial Neural Networks ; FPNN) 모델을 이용하여 비선형성 데이터에 대한 추론을 제안한다. 복잡한 비선형 시스템의 모델동정을 위하여 생성된 GMDH 방법에 기초한 FPNN의 각 노드는 퍼지 규칙을 기반으로 구축되었으며, 층이 진행되는 동안 모델 스스로 노드의 선택과 제거를 통해 최적의 네트워크 구조를 생성할 수 있는 유연성을 가지고 있다. FPNN 각각의 활성노드를 퍼지다항식 뉴론(Fuzzy Polynomial Neuron ; FPN)이라고 표현한다. FPNN의 후반부 구조는 입출력 변수 사이 의 간략과 회귀다항식 (1차, 2차, 변형된 2차식) 함수에 의해 구현된다. 규칙의 전반부 멤버쉽 함수는 삼각형과 가우시안형의 멤버쉽 함수가 사용된다. 또한 유전자 알고리즘을 사용하여 각노드의 부분표현식을 구성하는 입력변수의 수, 입력변수와 차수의 선택 동조를 통하여 최적의 Genetic Algorithms(GAs)을 이용한 FPNN모델을 설계하는 것이 유용하고 효과적임을 보인다.

• KSBB Journal
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• v.6 no.1
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• pp.99-103
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• 1991

The optimum conditions and rates of absorption of isobutylene in aqueous para-toluene sulfonic acid(PTSA) were studied experimentally in a stirred reactor. The effects of acid concentration(30-70 wt%), acid loading (0.3-5), mixing intensity(400-1000 rpm), and temperature ($20-80^{\circ}C$) on the absorption conditions were examined. The absorption rate of isobutylene was first order in isobutylene and variable order in PTSA concentrations. The apparent energy of activation was found to be 13 Kcal/mole.

• Proceedings of the Korea Water Resources Association Conference
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• 2004.05b
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• pp.719-723
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• 2004

본 연구에서는 일 최고, 최소치 유출량 계열을 확충하기 위해 ARIMA(p,d,q) 모형을 이용하였으며, 분석 자료의 경향성 유무를 파악하기 위해 Mann-Kendal 비모수적 검정을 실시하였다. 분석 결과, 최고 최소 유출량 자료 모두 경향성이 없는 것으로 분석되었다. ARIMA(p,d,q) 모형의 최적 차수를 결정하기 위해 ACF, PACF, AIC, 그리고 SBC(Schwarz Bayesian Criterion) 검사를 실시하였으며 이를 통해 최적의 ARMA 모형을 결정하였다. 일 최대치 자료의 경우 추계학적 경향 보다는 무작위적 특성을 보였으며, 일 최소치 자료계열 경우, ARMA(1,0) 모형이 최적 모형으로 선정되었다.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.36S no.4
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• pp.83-92
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• 1999

본 논문에서는 Jue Chang 과 John R. Glover 가 1993년에 제안한 회귀적 적응 주기 신호 검출기[1]를 소개하고 이를 구현하기 위한 최적의 실시간 알고리즘을 제안하여 회귀적 주기 신호 검출기의 실용적인 응용 예를 제시하였다. 회귀적 적응 주기신호 검출기(FALE:Feedback Adaptive Line Enhancer)는 기존의 적응 주기 신호 검출기에 회귀 경로를 달아줌으로써, 필터 차수를 같게 했을 때 낮은 신호 대 잡음비 환경 하에서 더 높은 필터 이득과 더 낮은 추정 오차를 얻을 수 있다. 회귀 경로를 통해 들어오는 필터 출력 신호는 회귀 이득 상수 값에 따라 전체 시스템의 성능이 달라지므로 최적의 회귀 이득 상수를 찾아내는 것이 중요하며 이는 회귀 이득 상수를 변화시키며 최적의 결과값(최소 추정오차)을 유도하는 실험을 통해 얻을 수 있다. 한편, 이를 구현하는 문제에 있어서는 일잔 최적의 회귀 이득 상수 값이 정해지면 회귀 이득 상수가 초기 값으로부터 최적 값에 도달하는 변화율과 변화 유형이 시스템의 실시간 구현 및 성능에 중요한 영향을 미치게 된다. 본 논문에서는 실험을 통해 최적의 구현 알고리즘을 찾아냄으로써 Jue Chang 과 John R, Glover가 제시한 이론적인 수렴율과 수렴 성능을 유지하면서 실시간으로 동작하는 시스템을 구현하고 모의실험을 통한 성능분석 결과를 제시하였다.

• The Journal of Engineering Geology
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• v.5 no.3
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• pp.289-300
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• 1995

At the initial stage of the underground reservoir design one should thoroughly consider surface and subsurface hydrology, hydrogeologic characteristics of aquifer system, and the function of cut - off wall because it is linked to the effective management. In this study, three dimensional finite difference model was applied to analyse the function of Ian underground reservoir at Kyungbuk Province. The steady and unsteady state conditions after construction of the underground dam were simulated through the model, and from these results the groundwater budget and the safe yield were determined. The model simulation indicates the infiltration of irrigation water to be one of the major factors of seasonal fluctuation of groundwater level. The recharge rates of irrigation water were estimated as 4.3mm/d during May and June, and 1.7mm/d during July and Agust. Groundwater recharge from the watershed area estimated to about $0.04m^3/s$, almost consistent through the year. In 1984, groundwater discharge through the transverse section of the dam was $0.002m^3/s$ and the optimum yield for two momths(July and Aguest)was $254000m^3$, however, the discharge became $0.013m^3/s$ in1993, implying the failure of cut -off function. without appropaiate of the cut - off wall, optiumum yield during the irrigaton period would be $93, 000m^3$.

• Journal of the Korean GEO-environmental Society
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• v.7 no.6
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• pp.45-56
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• 2006

Recently, the more potential waste sites are being required as increasing the demand of better human life. But the construction of waste disposals has many restrictions because of lack of good quality clay and high cost of liners. So, in this study, we studied the liner materials to develop more cheaper soil liner that can be satisfied the environmental criterion for the coefficient of permeability and shear strength. A series of compaction test and triaxial (consolidation, permeability, and shear) tests were performed to obtain the optimized weight ratio of Bentonite-Soil mixture (B/S) including the least amount of bentonite. A series of soil tests were performed to acquire the appropriate weathered granite soil-bentonite mixture that is satisfied the environmental criterion of soil liner($k=1{\times}10^{-7}cm/sec$). At first, weathered granite soils were classified with four different particle-size soils, and B/S ratio was increased as 5% step for each particle-size. The test results showed that in case of weathered granite soil passing through No. 100 sieve, B/S=15% satisfied the soil liner criterion. The measured coefficient of permeability and the Chapuis's two equations were also compared. And a predicting equation for the coefficient of permeability was suggested, which is suitable for the mixture soil with the B/S ratio used in this study. The optimal weight ratio for the mixture soils used in this study was 15% in the both cases of permeability and shear strength.