• Journal of Korea Multimedia Society
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• v.24 no.9
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• pp.1261-1267
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• 2021

Currently, the application of virtual reality technology is becoming more and more popular in all aspects of life. From virtual entertainment to industrial simulation, the new operation and working methods brought by virtual reality visualization technology have greater appeal and advantages. With the renewal and iteration of related equipment, more and more functions make its limitations continue to decrease, but its applicability continues to improve. Take the optically transparent head-mounted device as an example. It integrates more computer functions, presents and interacts in a virtual way, further integrates with daily behaviors, and shortens the distance between users and digital information.

• Journal of the Korean Society of Systems Engineering
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• v.17 no.1
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• pp.85-96
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• 2021

Radioactive mixed waste (RMW) means waste mixed with radioactive substances and hazardous substances. In Korea, there are definitions and disposal restrictions on RMW in the Nuclear Safety Management Act, but it is difficult to apply because the contents are insufficient, so this paper proposed applicable management standards. The main RMW generated from nuclear power plants is waste oil, waste asbestos, PCB, and waste fluorescent liquid, and their radiation characteristics are mostly at very low levels and some are estimated at low levels. In addition to nuclear power plants, RMW also occurs in research institutes, industries, and hospitals. The acceptance criteria of all disposal facilities in the world basically prohibit disposal of RMW unless the hazardous substances of RMW are removed or mitigated below the standard value. Cases in Korea, the United States, Japan and Europe were reviewed to propose the RMW management standards in Korea. With reference to the results of the above review, this paper clearly defined RMW and proposed detailed management standards for the separation, storage, treatment and disposal of hazardous substances by applying the Waste Control Act. It also mentioned legislation of management standards, regulatory methods, and acceptance criteria of disposal facility operator.

• Communications for Statistical Applications and Methods
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• v.12 no.2
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• pp.335-348
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• 2005

The rapid development of microarray technologies enabled the monitoring of expression levels of thousands of genes simultaneously. Recently, the time course gene expression data are often measured to study dynamic biological systems and gene regulatory networks. For the data, biologists are attempting to group genes based on the temporal pattern of their expression levels. We apply the consensus clustering algorithm to a time course gene expression data in order to infer statistically meaningful information from the measurements. We evaluate each of consensus clustering and existing clustering methods with various validation measures. In this paper, we consider hierarchical clustering and Diana of existing methods, and consensus clustering with hierarchical clustering, Diana and mixed hierachical and Diana methods and evaluate their performances on a real micro array data set and two simulated data sets.

• Journal of the korean academy of Pediatric Dentistry
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• v.33 no.2
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• pp.253-261
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• 2006

Estimating the size of unerupted teeth is an essential aspect of orthodontic diagnosis and treatment planning in the mixed dentition. Several methods were introduced and used for the prediction. The most common methods among these would be Moyers probability chart and Tanaka and Johnston equations. These are currently used widely, but they were developed for Caucasians. Because there are clear racial differences in teeth size, the objectives of this study were to produce correlation coefficients between the combined mesiodistal widths of the permanent mandibular incisors and those of the canines and premolars for each quadrant, and prediction tables with regression equations, specifically for Korean. 178 young adults (70 women, 108 men, mean age 21.63 years) were selected from the College of Dentistry, Yonsei University, Seoul, Korea. The mesiodistal crown diameters of the permanent teeth were measured with calipers. Significant sexual dimorphism was found in tooth sizes. The correlation coefficients between the total mesiodistal width of the mandibular permanent incisors and those of the maxillary and mandibular canines and premolars were found to be between 0.52 and 0.64. The standard error of the estimatation was better (0.60) for women and the ${\gamma}^2$ values ranged from 0.27 to 0.41 for both sexes Prediction tables were prepared for Korean. This study showed larger canine and premolar diameters than Tanaka and Johnston's and Moyers' studies which might be due to the racial differences. Further investigations with a larger sample size will be needed for more representative data on the Korean population.

• Corrosion Science and Technology
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• v.21 no.6
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• pp.423-433
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• 2022

The objective of this study was to determine whether Cymbopogon citratus extract as a corrosion inhibitor from natural tropical resources could prevent corrosion of carbon steel in sulfuric acid solution. Inhibitory action of this extract was investigated using electrochemical methods such as potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). Those methods revealed corrosion rate, efficiency of inhibition, and adsorptions isotherm values when the extract was added to the sulfuric acid solution at concentration up to 500 ppm with various immersion time at ambient temperature. Results revealed that higher concentration of the extract and longer immersion time decreased the corrosion rate of carbon steel whereas the inhibition efficiency of the extract was increased up to 97.25%. The value of charge transfer resistance was increased significantly by adding the extract at concentration up to 500 ppm with an immersion time of 60 minutes. The type of the extract was a mixed inhibitor. It could inhibit the corrosion process in both anodic and cathodic sides electrochemically. Results of this study suggest that the mechanism of adsorption on the surface of carbon steel is related to Langmuir adsorption isotherm.

• Journal of Intelligence and Information Systems
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• v.9 no.1
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• pp.71-89
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• 2003

Although many studies demonstrate that one technique outperforms the others for a given data set, there is often no way to tell a priori which of these techniques will be most effective in the classification problems. Alternatively, it has been suggested that a better approach to classification problem might be to integrate several different forecasting techniques. This study proposes the linearly combining methodology of different classification techniques. The methodology is developed to find the optimal combining weight and compute the weighted-average of different techniques' outputs. The proposed methodology is represented as the form of mixed integer programming. The objective function of proposed combining methodology is to minimize total misclassification cost which is the weighted-sum of two types of misclassification. To simplify the problem solving process, cutoff value is fixed and threshold function is removed. The form of mixed integer programming is solved with the branch and bound methods. The result showed that proposed methodology classified more accurately than any of techniques individually did. It is confirmed that Proposed methodology Predicts significantly better than individual techniques and the other combining methods.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.5D
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• pp.671-677
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• 2011

A diversity of railway network function enhancement projects such as the double tracking, electrification, and direct operation have been actively executed to improve the railway service. When the new rapid transit is provided, how many people will use it instead of other transports? How will the railway choice behavior be changed? Accordingly, in this paper, the applicability of diverted travel demand forecast methods, by Revealed Preference(RP) and Stated Preference(SP) data was reviewed for Daegu metropolitan rail rapid transit service. As the result of combining RP and SP data, including the sequential and simultaneous approach, the total travel time and travel cost parameters are of the right sign and are highly significant. The simultaneous approach is more efficient in terms of the estimation of coefficients. In particular, methods to improve validity of the Mixed RP/SP models, when RP data is used proportionally, the diverted travel demand can be easily identified by railway fare and travel time service level. Therefore, it is considered that this will practically apply even in other regions as well as Daegu metropolitan railway.

• Journal of the Korean Society of Clothing and Textiles
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• v.31 no.8
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• pp.1286-1296
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• 2007

Hanji, the korean traditional papers were mostly made from mulberry paper. But the production and demand of hanji have decreased rapidly because mulberry paper yields were insufficient and handworked hanji procedures were complicated. Recently, the researches on hanji were carried out to improve the properties of hanji. Kenaf fibers have been interested as a substitute resource of mulberry paper for hanji production. In this research, Kenai pulps were manufactured with removal methods of lignin or hemicellulose from kenaf fibers and paper mulberry pulps with traditional alkali methods. Kenaf papers, paper mulberry, and kenaf/paper mulberry mixed papers were manufactured with their pulps. The crystallinity, fiber length, color of the pulps and tensile strength, tear strength, water absorption of the papers were investigated. The results were as follow: The removal rates of lignin of chemical retted kenaf fibers with sodium chlorite reaction for 40 minutes were 70% and were higher than 40% of double retted fibers. Paper mulberry pulps has less lignin and hemicellulose than kenaf differently. The crystallinity of paper mulberry pulps were very low with 60%, but kenaf pulps were 90%. The chemical retted CR-40-1 pulps were similar with paper mulberry pulps on fiber length & fibrilation of fibers. Tensile strength of paper mulberry were higher than kenaf papers because of fibrilation of paper mulberry, but tear strength were lower. Tensile strength and tear strength were improved on kenaf/paper mulberry 30/70 mixed papers.

• The Korea Journal of Herbology
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• v.35 no.3
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• pp.33-45
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• 2020

Objective : The present study aimed to evaluate the change of the content of 7 active components in decoctions produced by various proportional pairs of Coptis chinensis Franch and Scutellaria baicalensis Georgi in 'Mixed decoction (MD)' and 'Single decoction mixture (SDM)'. Methods : The samples of MDs were prepared by decocting C. chinensis : S. baicalensis with the ratios of 10 g:10 g, 10 g:20 g, and 20 g:10 g. Those of SDMs were prepared by blending each single decoction from C. chinensis and S. Baicalensis with the ratios of 1:1, 1:2, and 2:1. The samples were evaluated by high-performance liquid chromatography with statistical analyses. Results : The analytical methods, which were optimized and validated, were reliably applied to present research. The content of all components in both MDs and SDMs at C. chinensis : S. baicalensis = 1:1 ratio were reduced compared with single herb decoction. The components from each compositional herb in MDs were proportionally increased with the ratio of original herb increased, but inversely proportional to paired herb. The contents of components in MDs were significantly lower than those in SDMs at all ratios, except for high content of baicalin at C. chinensis : S. baicalensis = 2:1. Conclusion : It was concluded that MDs and SDMs as well as the proportions of herbs could affect the contents of the components from original herbal medicines. These results provide the information for the quality control of herbal medicine combined C. chinensis with S. baicalensis.

• Composites Research
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• v.33 no.5
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• pp.268-274
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• 2020

This paper analyzed the degradation behaviors of silica nano epoxy composite based on the isoconversional method. The size of the silica nano particle was about 12 nm and the particles were mixed by three different weight ratios to make the degradation test samples. The thermogravimetric analyses were performed under six different temperature increase rates to measure the weight changes. Four different methods, Friedman, Flynn-Wall-Ozawa, Kissinger and DAEM (Distributed Activation Energy Method), were employed to calculate the activation energies depending on the conversion ratios, and their calculation results were compared. The results represented that the activation energy was increased when the silica nano particles were mixed up to 10%, indicating the definite contribution of the particles to the degradation behavior enhancements. However, the enhancement was not proportional to the particle mixture ratio by demonstrating the similar activation energies between 10% and 18% samples. The calculation results by the different methods were also compared and discussed.