• Proceedings of the Korea Inteligent Information System Society Conference
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• 1999.03a
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• pp.253-260
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• 1999

The recycling cell formation problem means that disposal products are classified into recycling part families using group technology in their end of life phase. Disposal products have the uncertainties of product status by usage influences during product use phase and recycling cells are formed design, process and usage attributes. In order to treat the uncertainties, fuzzy set theory and fuzzy logic-based neural network model are applied to recycling cell formation problem for disposal products. In this paper, a heuristic approach for fuzzy ART neural network is suggested. The modified Fuzzy ART neural network is shown that it has a great efficiency and give an extension for systematically generating alternative solutions in the recycling cell formation problem. We present the results of this approach applied to disposal refrigerators and the comparison of performances between other algorithms. This paper introduced a procedure which integrates economic and environmental factors into the disassembly of disposal products for recycling in recycling cells. A qualitative method of disassembly analysis is developed and its aim is to improve the efficiency of the disassembly and to generated an optimal disassembly which maximize profits and minimize environmental impact. Three criteria established to reduce the search space and facilitate recycling opportunities.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.3C
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• pp.331-337
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• 2007

In this paper, we propose a novel Walsh coded training signal design and Walsh decoding method to estimate the channel response in MIMO-OFDM systems. The Walsh coded training signals are designed to have orthogonal property in time domain. Using the orthogonal property, the Walsh decoding process makes it possible to separate the desired training signal from the received signal and to estimate the channel response. The computer simulation results show that the proposed method exhibits almost the same performance as Li's original method using the optimal training sequence, even though the proposed method has much lower complexity.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2007.04a
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• pp.565-570
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• 2007

Fiber reinforced polymer(FRP) composite decks are new to bridge applications and hence not much literature exists on their structural mechanical behavior. As there are many differences between numerical displacements through static analysis of the primary model and experimental displacements through static load tests, system identification (SI)techniques such as Neural Networks (NN) and support vector machines (SVM) utilized in the optimization of the FE model. During the process of identification, displacements were used as input while stiffness as outputs. Through the comparison of numerical displacements after SI and experimental displacements, it can note that NN and SVM would be effective SI methods in modeling an FRP deck. Moreover, two methods such as response surface method and iteration were proposed to optimize the estimated stiffness. Finally, the results were compared through the mean square error (MSE) of the differences between numerical displacements and experimental displacements at 6 points.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.16 no.2
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• pp.113-122
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• 2016

In this paper, we suggest a approach which comprises fast Fourier transform inversion by wavelet noise attenuation. It represents an inverse filtering by adopting a factor into the Wiener filtering, and the optimal factor is chosen to minimize the overall mean squared error. in order to apply the Wiener filter, we have to compute the power spectrum of original image from the corrupted figure. Since the Wiener filtering contains the inverse filtering process, it expands the noise when the blurring filter is not invertible. To remove the large noises, the best is to remove the noise using wavelet threshold. Wavelet noise attenuation steps are consisted of inverse filtering and noise reduction by Wavelet functions. experimental results have not outperformed the other methods over the overall restoration performance.

• Journal of Information Technology Applications and Management
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• v.12 no.2
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• pp.1-13
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• 2005

This paper proposes a software-reliability growth model incoporating the amount of testing effort expended during the software testing phase after developing it. The time-dependent behavior of testing effort expenditures is described by a Logistic curve. Assuming that the error detection rate to the amount of testing effort spent during the testing phase is proportional to the current error content, a software-reliability growth model is formulated by a nonhomogeneous Poisson process. Using this model the method of data analysis for software reliability measurement is developed. After defining a software reliability, This paper discusses the relations between testing time and reliability and between duration following failure fixing and reliability are studied. SRGM in several literatures has used the exponential curve, Railleigh curve or Weibull curve as an amount of testing effort during software testing phase. However, it might not be appropriate to represent the consumption curve for testing effort by one of already proposed curves in some software development environments. Therefore, this paper shows that a logistic testing-effort function can be adequately expressed as a software development/testing effort curve and that it gives a good predictive capability based on real failure data.

• Structural Engineering and Mechanics
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• v.83 no.1
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• pp.79-92
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• 2022

In this paper, the impact of a vernacular pozzolanic kaolinite mine on concrete alkali-silica reaction and strength has been evaluated. For making the samples, kaolinite powder with various levels has been used in the quality specification test of aggregates based on the ASTM C1260 standard in order to investigate the effect of kaolinite particles on reducing the reaction of the mortar bars. The compressive strength, X-Ray Diffraction (XRD) and Scanning Electron Microscope (SEM) experiments have been performed on concrete specimens. The obtained results show that addition of kaolinite powder to concrete will cause a pozzolanic reaction and decrease the permeability of concrete samples comparing to the reference concrete specimen. Further, various machine learning methods have been used to predict ASR-induced expansion per different amounts of kaolinite. In the process of modeling methods, optimal method is considered to have the lowest mean square error (MSE) simultaneous to having the highest correlation coefficient (R). Therefore, to evaluate the efficiency of the proposed model, the results of the support vector machine (SVM) method were compared with the decision tree method, regression analysis and neural network algorithm. The results of comparison of forecasting tools showed that support vector machines have outperformed the results of other methods. Therefore, the support vector machine method can be mentioned as an effective approach to predict ASR-induced expansion.

• Korean Journal of Veterinary Research
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• v.43 no.3
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• pp.493-500
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• 2003

This study was performed to determine the optimal dose of ozone for wound healing. Twenty Korean black goats were allocated to 4 groups. The skin wound with $1{\times}1cm$ was induced over the hoof. For 5 minutes per day, 0.1 ppm (Group I), 1 ppm (Group II) and 6 ppm (Group III) ozone gas was applied. In control group, 5 ml of normal saline was applied daily on the wound. Wound square was determined using color image analyzer at day 0, 4 and 14. Soft tissue depth of wound was determined using radiograph. Before the application of ozone gas, $1{\times}1cm$ of skin tissue was resected and observed for histopathologic findings. To determine the healing effect, $2{\times}1cm$ of wound tissue was resected and observed for histopathologic findings at day 14. In mean squares of wound, all experimental groups revealed more reduced mean squares than control group at day 4, and especially Group II (p<0.05) and Group III (p<0.05) revealed significant reduction. At day 14, Group I and Group II (p<0.05) revealed more reduced mean squares than control group, but Group III revealed less reduced mean squares than control group. In soft tissue depth of wound, all experimental groups and control group revealed swelling at day 4, compared with day 0. At day 14, all experimental groups and control group revealed reduction, compared with day 4, and especially Group II (p<0.05) revealed significant reduction. In histopathological findings, inflammation findings in epidermis and dermis, hemorrhagic finding in epidermis were revealed in control group. In Group I, inflammation finding was reduced, compared with control group. Formation of scab and many reepithelialization of epidermis were revealed. In Group II, inflammation findings in epidermis and dermis which were observed in control group were not found, normal skin tissue was revealed. In Group III, inflammation findings in epidermis and dermis were revealed, reepithelialization of epidermis was not founded. Slow healing process was observed, compared with Group I and II. It was concluded that Group II has excellent promotion effect of wound healing.

• The Journal of Engineering Geology
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• v.14 no.1
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• pp.21-28
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• 2004

Three-dimensional (3-D) resistivity inversion including a topographic effect can be considered theoretically to be the technique of acquiring the most accurate image in the interpretation of resistivity data, because it includes characteristic image that the actual subsurface structure is 3-D. In this study, a finite-element method was used as the numerical method in modeling, and the efficiency of Jacobian calculation has been maximized with sensitivity analysis for the destination block in inversion process. Also, during the iterative inversion, the resolution of inversion can be improved with the method of selecting the optimal value of Lagrange multiplier yielding minimum RMS(root mean square) error in the parabolic equation. In this paper, we present synthetic examples to compare the difference between the case which has the toprographic effect and the other case which has not the effect in the inversion process.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.29 no.2
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• pp.259-269
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• 2019

Objective: This study was conducted to prepare fundamental data and assess the relationship between level of exposure to airborne respirable dust, chest radiation findings, and the results of pulmonary function tests among workers in a cloth manufacturing factory. Methods: The number of total subjects was 144 (124 female and 20 male) workers in a cloth manufacturing factory in the city of Busan. This study measured the concentration of airborne respirable dust by gravimetric analysis and performed pulmonary function testing, and got chest radiation findings from December 1, 2016 to March 31, 2017. Collected data was analyzed using the IBM SPSS statistical package program (ver. 24.0). Results: The mean concentration of respirable dust was the highest in the cutting process. The effecting factors on $FEV_1/FVC$ were age, sex, and working process. The effecting factors on chest radiation findings were doing no exercise and concentration of respirable dust. Conclusions: Based on the above results, the authors consider there to be a need to secure sufficient working space and improve the engineering systems, for example the overall or local ventilation, in order to minimize the exposure to respirable dust. Health education and health promotion activities should also be improved in order to maintain optimal health status. The authors expect further studies to be performed on pulmonary function testing, chest radiation findings, and symptoms related to pulmonary function, including continuous observation, among workers in a cloth manufacturing factory.

• Applied Chemistry for Engineering
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• v.34 no.2
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• pp.137-143
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• 2023

In this study, natural surfactants were extracted from Medicago sativa L. The O/W emulsification processes with the extracted natural surfactants were optimized using central composite design model-response surface methodology (CCD-RSM) and a 95% confidence interval was used to confirm the reasonableness of the optimization. Herein, independent parameters were the ratio of saponins to total surfactant (P), amount of surfactant (W), and emulsification speed (R), whereas the reaction parameters were the emulsion stability index (ESI), mean droplet size (MDS), and viscosity (V). Using the multiple reaction, the optimal conditions for the ratio of saponins to total surfactant, amount of surfactant, and emulsification speed for O/W emulsification were 49.5%, 9.1 wt%, and 6559.5 rpm, respectively. Under these optimal conditions, the expected values of ESI, MDS, and V as the reaction parameters were 89.9%, 1058.4 nm, and 1522.5 cP, respectively. The values of ESI, MDS, and V from these expected values were 88.7%, 1026.4 nm, and 1486.5 cP, respectively, and the average experimental error for validating the accuracy was about 2.3 (± 0.4)%. Therefore, it was possible to design an optimization process for evaluating the O/W emulsion process with Medicago sativa L. using CCD-RSM.