• Membrane Journal
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• v.9 no.4
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• pp.221-229
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• 1999

The nominal pore size 0.2 ${\mu}m polytetrafluroethylene(PTFE, Satorius Co,) membrane was used for the filtration of 0.1 wt% kaolin, bentonite, yeast, and starch solution, respectively. After filtration, the membrane was cleaned and the pore size was measured by liquid displacement method(LDMl using water/iso-butanol system. The pore size for new PTFE membrane evaluated by LDM was comparable with those of which were measured by mercury porosimetry and scanning electron microscope. The membrane pores were severely fouled, and constricted to below 0.3 ${\mu}m in the cases of bentonite and starch solution which contained smaller particles than pores. However, in the case of kaolin - solution, only some parts of membrane pores above 0.35 ${\mu}m were slightly fouled. Hence, the phenomena of membrane fouling could be identified quantitatively by the evaluation of pore size using LDM.

• Journal of Korean Tunnelling and Underground Space Association
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• v.20 no.1
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• pp.39-53
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• 2018

Generally, the total ventilation resistance coefficient in a tunnel consists of inlet/outlet loss coefficient, wall friction coefficient, and other loss coefficient caused by sudden expansion and contraction of cross-section, etc. For the tunnel before opening, when the running ventilation fan is stopped, the wind speed in the tunnel is reduced by the total ventilation resistance drag. The velocity decay method is comparatively stable and easy to estimate the wall friction coefficient in the pre-opening tunnel. However, the existing study reported that when the converging wind speed is a negative value after the ventilation fan stops, it is difficult to estimate the wall friction coefficient according to the velocity decay method. On the other hand, for the operating tunnel in which the piston effect acts, a more complex process is performed; however, a reasonable wall friction coefficient can be estimated. This paper aims at suggesting a method to minimize the measurement variables of the piston effect and reviewing a method that can be applied to the operating tunnel. Also, in this study, a new method has been developed, which enables to calculate an variation of the piston effect if the piston effect is constant with a sudden change of external natural wind occurring while the wind speed in the tunnel decreases after the ventilation fan stops, and a programming logic has been also developed, which enables dynamic simulation analysis in order to estimate the wall friction coefficient in a tunnel.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.1355-1356
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• 2015

본 논문에서는 Convolution기법 기반 RBFNNs 패턴 분류기를 사용한 2차원 얼굴인식 시스템을 설계한다. 제안된 방법은 특징 추출과 차원축소를 하는 컨볼루션 계층과 부분추출 계층을 교대로 연결하여 2차원 이미지를 1차원의 특징 배열로 만든다. 그 후, 만들어진 1차원의 특징 배열을 RBFNNs 패턴 분류기의 입력으로 사용하여 인식을 수행한다. RBFNNs의 조건부에는 FCM 클러스터링 알고리즘을 사용하며 연결가중치는 1차 선형식을 사용하였다. 또한 최소 자승법(LSE : Least Square Estimation)을 사용하여 다항식의 계수를 추정하였다. 제안된 모델의 성능을 평가하기 위해 CMU PIE Database를 사용한다.

• The Korean Journal of Applied Statistics
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• v.22 no.3
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• pp.531-539
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• 2009

Logistic regression is widely used as a datamining technique for the customer relationship management. The maximum likelihood estimator has highly inflated variance when multicollinearity exists among the regressors, and it is not robust against outliers. Thus we propose the robust principal components logistic regression to deal with both multicollinearity and outlier problem. A procedure is suggested for the selection of principal components, which is based on the condition index. When a condition index is larger than the cutoff value obtained from the model constructed on the basis of the conjoint analysis, the corresponding principal component is removed from the logistic model. In addition, we employ an algorithm for the robust estimation, which strives to dampen the effect of outliers by applying the appropriate weights and factors to the leverage points and vertical outliers identified by the V-mask type criterion. The Monte Carlo simulation results indicate that the proposed procedure yields higher rate of correct classification than the existing method.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.44 no.1
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• pp.25-32
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• 2007

In this paper, a new method for first order plus dead time(FOPDT) model identification is proposed, which can identity multiple points on a process step response in terms of classification of time response. The process input and output to the test are decomposed into the transient part and the steady-state part. The steady-state part express one FOPDT model and the transient part express variously FOPDT model using least square estimation method. The optimum parameter tuning algorithm for PID controller of the Smith Predictor is proposed through ITAE as performance index. The Simulation results show the validity and improvement of performance for various processes.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.1A
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• pp.9-18
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• 2009

This paper introduces the application of DE (Differential Evolutionary) method for the estimation of tensile force of the externally prestressed tendon. The proposed technique, a SI (System Identification) method using the DE algorithm, can make global solution search possible as opposed to classical gradient-based optimization techniques. The numerical tests show that the proposed technique employing DE algorithm is a useful method which can detect the effective nominal diameters as well as estimate the exact tensile forces of the externally prestressed tendon with an estimation error less than 1% although there is no a priori information about the identification variables. In addition, the validity of the proposed technique is experimentally proved using a scale-down model test considering the serviceability state condition without and with the loss of the prestressed force. The test results prove that the technique is a feasible and effective method that can not only estimate the exact tensile forces and detect the effective nominal diameters but also inspect the damping properties of test model irrespective of the loss of the prestressed force. The 2% error of the estimated effective nominal diameter is due to the difference between the real tendon diameter with a wired section and the FE model diameter with a full-section. Finally, The accuracy and superiority of the proposed technique using the DE algorithm are verified through the comparative study with the existing theories.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.3B
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• pp.269-276
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• 2010

Climatic disasters are globally soaring due to recent acceleration of global warming. Especially the occurrence frequency of heavy rainfalls is increasing since the rainfall intensity is increasing due to the change of rainfall pattern, This study proposed the non-stationary frequency analysis for estimating design rainfalls in a design target year, considering the change of rainfall pattern through the climatic change scenario. The annual rainfalls, which are regionally downscaled from the BCM2 (A2 scenario) and NCEP data using a K-NN method, were used to estimate the parameters of a probability distribution in a design target year, based on the relationship between annual mean rainfalls and distribution parameters. A Gumbel distribution with a probability weighted method was used in this study. Seoul rainfall data, which are the longest observations in Korea, were used to verified the proposed method. Then, rainfall data at 7 stations, which have statistical trends in observations in 2006, were used to estimate the design rainfalls in 2020. The results indicated that the regional annual rainfalls, which were estimated through the climate change scenario, significantly affect on the design rainfalls in future.

• Journal of the Institute of Convergence Signal Processing
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• v.8 no.4
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• pp.255-265
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• 2007

In case of wavelet coefficients have correlation, in image signal denoising using wavelet shrinkage denoising method, the denoising effect for the image signal is reduced when the wavelet shrinkage denoising method is used. The coefficients of multiwavelet transform have correlation by pre-filters. To solve the degradation problem in multiwavelet transform, V Sterela suggested a new pre-filter for the Universal threshold or weighting factors to the threshold. In this paper, to improve the denoising effect in the multiwavelet transform, the coefficient normalizing method that the coefficient are divided by estimated noise deviation is adopted to the transformed multiwavelet coefficients in the course of wavelet shrinkage technique. And the thresholds of universal, SURE and GCV are estimated using normalized coefficients and tried to denoise by the wavelet shrinkage technique. We compared PSNRs of denoised images for each thresholds and confirmed the efficiency of the proposed method.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.20 no.2
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• pp.1-14
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• 2021

The exclusive bus lanes in the Yeongdong Expressway were implemented in the Singal to Yeoju section in 2017, but the capacity of both exclusive bus lanes and general-purpose lanes of the Yeongdong Expressway decreased and the travel time increased, reducing it to the Singal to Deokpyeong section. Therefore, it is necessary to increase the efficiency of exclusive bus lanes to revitalize public transportation and improve environmental problems. This study calculated the willingness to pay and the social benefits of permission for Green cars to drive on exclusive bus lanes in Yeongdong Expressway. A survey was conducted on two groups of Green car users and Expressway users, and the willingness to pay was estimated using the CVM method. As a result, the average WTP of Green car users were estimated to be 218.7(won/km·person), and that of Expressway users were estimated to be approximately 235.5(won/km·person). The direct benefits were estimated to be approximately 7.9 billion won for Green car users, and 8.5 billion won for Expressway users in 2019. Finally, the value of time saving was estimated to be approximately 8.0 billion won.

• Journal of Korea Society of Industrial Information Systems
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• v.23 no.2
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• pp.19-28
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• 2018

In this paper, we studied on the sampling of ocean meteorological data to analyze signature of naval ships. The newest ocean meteorological data, that was quality controled by the Korea Meteorological Administration(KMA), was collected. Outliers were removed from the data by setting the usable range of data. After that, the data size was reduced through the random sampling method, taking geopolitical significance and effective area of buoy, for probabilistic analysis. Moreover, the sample sizes were set at 100, 200, and 400 by considering the population size and a 95% confidence level. The final sample was obtained using the two-dimensional stratified sampling method based on highly correlated water temperature and air temperature. The sum of the squared errors and the confidence interval was calculated to compare the result of sampling. As a result, this study proposed reasonable sample size for infra­red signature analysis of naval ships.