• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.3
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• pp.230-236
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• 2020

A trash screen is installed in front of the inflow channel of a drainage pumping station, sewage treatment plant, and a power plant to block floating contaminants. The bottleneck phenomenon, which decreases the water inflow, causes damage to the damper as a result of clogging in between the screen if string type obstacles are not removed. In this paper, the apron was removed, and the screen was expanded, to prevent breakage of the bottleneck phenomenon and string type obstacles. This was designed using an extended rake by adding an inner rake in between the screen interspace to remove the bottleneck phenomenon and string type obstacles. To design the inner rake that satisfies the allowable stresses of the existing damper rake, the experiment points were determined according to the experimental design method using the inner rake vertical length and the thickness of the reinforced section as parameters. The use of the ANSYS static structural module and statistical analysis tool R software gives the optimized shape according to the response surface method. The relative error between the response surface analysis results and the simulation results was 1.63% of the determined optimal design-point rake length of 210.2 mm and the reinforcement section thickness of 2 mm. Through empirical experiments, a test rake was constructed to the actual size, and approximately 97% of the bottleneck phenomenon and string type obstacles could be removed.

• Analytical Science and Technology
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• v.29 no.6
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• pp.255-260
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• 2016

Based on the Korean Health Functional Food Act, health functional foods are dietary supplements containing nutrients or other substances that have nutritional or physiological effects. Since generic health functional food items have been expanded, this project was performed to develop a standardized analytical method of examining such sale items. The method exhibited high linearity in the quercetin calibration curve ($R^2$ > 0.999) over concentrations of $0-40{\mu}g/mL$. The limits of detection and quantitation for quercetin were $0.12{\mu}g/mL$ and $0.36{\mu}g/mL$, respectively, while quercetin recovery was 97.1-105.4 % with standard deviations of 1.15-3.11 %. To verify the accuracy of the analytical methods, the labeled amounts of purchased health functional foods were monitored. The recovery rate for multiple quercetin concentrations ranged from 82.5-105.1 % of the labeled amounts. Thus, the new method was suitable for all cases.

• Communications of Mathematical Education
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• v.34 no.3
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• pp.393-419
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• 2020

Trigonometry allows us to recognize the usefulness of mathematics through connection with real life and other disciplines, and lays the foundation for the concept of higher mathematics through connection with trigonometric functions. Since international comparisons on the trigonometry area of textbooks can give implications to trigonometry teaching and learning in Korea, this study attempted to compare trigonometry in textbooks in Korea, Australia and Finland. In this study, through the horizontal and vertical analysis presented by Charalambous et al.(2010), the objectives of the curriculum, content system, achievement standards, learning timing of trigonometry content, learning paths, and context of problems were analyzed. The order of learning in which the three countries expanded size of angle was similar, and there was a difference in the introduction of trigonometric functions and the continuity of grades dealing with trigonometry. In the learning path of textbooks on the definition method of trigonometric ratios, the unit circle method was developed from the triangle method to the trigonometric function. However, in Korea, after the explanation using the quadrant in middle school, the general angle and trigonometric functions were studied without expanding the angle. As a result of analyzing the context of the problem, the proportion of problems without context was the highest in all three countries, and the rate of camouflage context problem was twice as high in Korea as in Australia or Finland. Through this, the author suggest to include the unit circle method in the learning path in Korea, to present a problem that can emphasize the real-life context, to utilize technological tools, and to reconsider the ways and areas of the curriculum that deal with trigonometry.

• Journal of the Korean Data and Information Science Society
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• v.24 no.4
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• pp.689-699
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• 2013

This paper studies the partial credibility application method by assuming the empirical prior or noninformative prior informations in auto insurnace business where intensive rating segmentation is expanded because of premium competition. Expanding of rating factor segmetation brings the increase of pricing cells, as a result, the number of cells for partial credibility application will increase correspondingly. This study is trying to suggest more accurate estimation method by considering the Bayesian framework. By using empirically well-known or noninformative information, inducing the proper posterior distribution and applying the Bayes estimate which is minimizing the error loss into the credibility method, we will show the advantage of Bayesian inference by comparison with current approaches. The comparison is implemented with square root rule which is a widely accepted method in insurance business. The convergence level towarding to the true risk will be compared among various approaches. This study introduces the alternative way of redcuing the error to the auto insurance business fields in need of various methods because of more segmentations.

• The KIPS Transactions:PartA
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• v.11A no.5
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• pp.365-372
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• 2004

Recently, the studies for mesh simplification have been increased according to the application area of the complicate 3D mesh models has been expanded. This paper introduces a novel method for mesh simplification which uses the properties of the mesh model in addition to the geometric locations of the model. The information of the 3D mesh model Includes surface properties such as color, texture, and curvature information as well as geometic information of the model. The most of current simplification methods adopt such geometric information and surface properties individually for mesh simplification. However, the proposed simplification method combines the geometric information and solace properties and applies them to the simplification process simultaneously. In this paper, we exploit the extended geometry based quadric error metric(QEM) which relatively allows fast and accurate geometric simplification of mesh. Thus, the proposed mesh simplification utilizes the quadric error metric based on geometric information and the surface properties such as color, normal, and texture. The proposed mesh simplification method can be expressed as a simple quadric equation which expands the quadric error metric based on geometric information by adding surface properties such as color, normal, and texture. From the experimental results, the simplification of the mesh model based on the proposed method shows the high fidelity to original model in some respects such as global appearance rather than using current geometry based simplification.

• The KIPS Transactions:PartB
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• v.14B no.6
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• pp.453-460
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• 2007

In this paper, we present a method to extract the text lines in poorly structured documents. The text lines may have different orientations, considerably curved shapes, and there are possibly a few wide inter-word gaps in a text line. Those text lines can be found in posters, blocks of addresses, artistic documents. Our method based on the traditional perceptual grouping but we develop novel solutions to overcome the problems of insufficient seed points and vaned orientations un a single line. In this paper, we assume that text lines contained tone connected components, in which each connected components is a set of black pixels within a letter, or some touched letters. In our scheme, the connected components closer than an iteratively incremented threshold will make together a chain. Elongate chains are identified as the seed chains of lines. Then the seed chains are extended to the left and the right regarding the local orientations. The local orientations will be reevaluated at each side of the chains when it is extended. By this process, all text lines are finally constructed. The proposed method is good for extraction of the considerably curved text lines from logos and slogans in our experiment; 98% and 94% for the straight-line extraction and the curved-line extraction, respectively.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.12 no.3
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• pp.321-326
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• 2019

Image denoising methods based on block matching are founded on the experimental observations that neighboring patches or blocks in images retain similar features with each other, and have been proved to show superior performance in denoising different kinds of noise. The methods, however, take into account only neighboring blocks in searching for similar blocks, and ignore the characteristic features of the reference block itself. Consequently, denoising performance is negatively affected when outliers of the Gaussian distribution are included in the reference block which is to be denoised. In this paper, we propose an expanded block matching method in which noisy images are first decomposed into a number of bit-planes, then the range of true signals are estimated based on the distribution of pixels on the bit-planes, and finally outliers are replaced by the neighboring pixels belonging to the estimated range. In this way, the advantages of the conventional Gaussian filter can be added to the blocking matching method. We tested the proposed method through extensive experiments with well known test-bed images, and observed that performance gain can be achieved by the proposed method.

• Clean Technology
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• v.27 no.2
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• pp.132-138
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• 2021

Research is being conducted on graphene to provide graphene having both excellent physical as well as electrical properties in addition to unique physical properties. In this study, Hummer's method, which is a representative method for chemical exfoliation, was applied in order to investigate the possibility of the mass production of high-quality graphene oxide. Three types of graphite (graphite, crystalline graphite, and expanded graphite) were used in the preparation of graphene oxide with variations in the amount of potassium permanganate added, reaction temperature, and reaction time. Then a Fourier transform infrared spectroscopy (FT-IR), a Raman spectrometer, and a transmission electron microscope (TEM) were used to measure the quality of the prepared graphene oxide. Of the three types of graphite used in this experiment, crystalline graphite showed the highest quality. The prepared graphene oxide was then purified with an organic solvent, and an analysis conducted using energy dispersive X-ray spectroscopy (EDS). From the results of the residual values, we were able to confirm that both acid wastewater and wastewater were best purified using cyclohexane. The method for manufacturing graphene oxide as well as the method of purification using organic solvents that are presented in this study are expected to have less of an environmental impact, making them environmentally friendly. This makes them suitable for use in various industrial fields such as the film industry and for heat dissipation and as coating agents.

• Journal of Korean Tunnelling and Underground Space Association
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• v.12 no.6
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• pp.407-416
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• 2010

A new tunnel auxiliary method is proposed in this paper which utilizes the concept of cavity expansion for tuunel reinforcement by forming an umbrella arch on the roof of tunnel. When an inflatable pipe is inserted and expanded by pressure in the bore hole of umbrella arch, the ground around the bore hole can be compacted so that the stress condition above the tunnel perimeter is favorably changed. In order to verify the reinforcement effect of new concept, pilot-scale chamber test, trapdoor test and numerical analysis were performed and compared. In pilot-scale chamber test, three types of inflatable pipes are tested to verify the capability of expansion, and the results arc compared with analytical results obtained by applying cavity expansion theory and with results obtained from finite clement analysis, and the experimental results showed agreeable matches with analytical and numerical ones. Numerical analysis of a tunnel and trapdoor test applied with the inflatable pipes are also performed to figure out the reinforcement effect of the proposed techniques, and the results implied that the new method with 3 directional inflatable pipe (no pressure to downward direction) can contribute to reduce tunnel convergence and face settlement.

• Environmental and Resource Economics Review
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• v.33 no.3
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• pp.203-239
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• 2024

The introduction of a regional differential electricity rate system is being discussed, and the LMP (Locational Marginal Price) method is mentioned as a promising alternative. Under this background, this study analyzed a mathematical model and suggests that the LMP method produces results that maximize social welfare. The analysis was conducted separately for long-term decision-making where transmission capacity can be expanded, and for short-term decision-making in which transmission capacity is given. The analysis for short-term decision-making was conducted for peak load situations where capacity is insufficient and for non-load situations with spare capacity. The results of the analysis suggested that the price to maximize social welfare is equal to the marginal power generation cost by region, and the difference in marginal cost by region reflects the value lost due to transmission loss and compensation for transmission network investment. In addition, if the transmission capacity is less than the optimal capacity, the compensation for transmission network investment exceeds the incremental cost, providing an incentive to invest in the transmission network. If the transmission capacity exceeds the optimal capacity, the compensation for transmission network investment becomes lower than incremental cost or zero and the investment is not recovered, suppressing the investment in transmission networks. The results are the same as the LMP method suggests, and this means that this method maximizes social welfare and provides an optimal transmission network investment signal. The above analysis results contribute to understanding the characteristics of LMP. In addition, this study discussed what changes are needed in the electricity market when introducing the LMP concept.