• Journal of Powder Materials
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• v.22 no.2
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• pp.100-104
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• 2015

The porous metals are known as relatively excellent characteristic such as large surface area, light, lower heat capacity, high toughness and permeability. The Fe-Cr-Al alloys have high corrosion resistance, heat resistance and chemical stability for high temperature applications. And then many researches are developed the Fe-Cr-Al porous metals for exhaust gas filter, hydrogen reformer catalyst support and chemical filter. In this study, the Fe-Cr-Al porous metals are developed with Fe-22Cr-6Al(wt) powder using powder compaction method. The mean size of Fe-22Cr-6Al(wt) powders is about $42.69{\mu}m$. In order to control pore size and porosity, Fe-Cr-Al powders are sintered at $1200{\sim}1450^{\circ}C$ and different sintering maintenance as 1~4 hours. The powders are pressed on disk shapes of 3 mm thickness using uniaxial press machine and sintered in high vacuum condition. The pore properties are evaluated using capillary flow porometer. As sintering temperature increased, relative density is increased from 73% to 96% and porosity, pore size are decreased from 27 to 3.3%, from 3.1 to $1.8{\mu}m$ respectively. When the sintering time is increased, the relative density is also increased from 76.5% to 84.7% and porosity, pore size are decreased from 23.5% to 15.3%, from 2.7 to $2.08{\mu}m$ respectively.

• Journal of Digital Convergence
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• v.13 no.7
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• pp.293-304
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• 2015

Meta-analysis was conducted to examine effects of computer based virtual reality on clinical rehabilitation in Korea. The data were analyzed as the ICF categorizations. The papers used in this study were located through domestic data search engines. The fifteen studies were selected among the studies published between 1995 and 2014. The PEDro score was used for qualitative assessment. The sample size and the average and standard deviations of pre and post tests were analyzed through a meta-analysis. The PEDro scores of the selected studies were 6 points higher and 338 participants were involved. The effect size of combined data was 1.030, activities and participation 1.120, sensory function 1.199 as indicated by a "large effect size" and the effect size of mental function was 0.557 as indicated by a "medium effect size." As a result, virtual reality program as a adjunctive therapeutic methods has proven the effect. In particular, the effects were demonstrated in activities and participation, sensory function. However there was no evidence of the effectiveness of mental function.

• Journal of Ecology and Environment
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• v.38 no.4
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• pp.611-618
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• 2015

Spirogyra is a zygnematalean green algal genus that is ubiquitous in a broad range of freshwater habitats throughout the world. Samples collected throughout Korea from October 2004 to July 2015 were examined using light microscopy. Morphological characteristics (e.g., size of vegetative cells, number of chloroplasts in each cell, type of end walls of adjacent cells, details of conjugation, shape of female gametangia, dimensions and shape of zygospores, color and ornamentation of median spore walls) were used as diagnostic characteristics for species identification. In this study, five species of Spirogyra (i.e., S. emilianensis Bonhomme, S. jaoensis Randhawa, S. pascheriana Czurda, S. weberi var. farlowii (Transeau) Petlovany, and S. weberi var. grevilleana (Hassall) Kirchner) were described as newly recorded in Korea.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.28 no.12
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• pp.792-796
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• 2015

With high integration of electronic components, power inductors are also miniaturized. Recently, thick film processes for small size power inductors were developed and commercialized. However, the thick film process to prepare soft magnetic green sheets was not reported enough. In this study, we used Fe-Si magnetic and CIP (carbonyl iron powders) as starting materials to lead to a bimodal particle size distribution in the sheet. We proposed a newly developed 'Modified slurry preparation process' to get well dispersed condition even at high solid contents. Using the new process, it was possible to prepare a well dispersed slurry over 70 vol% of solid. BYK-103 was better than BYK-111 as dispersant in this slurry and the optimum amount was 0.6 wt%. The optimized slurry was formed into a sheet by tape casting process and then the sheet was laminated. We conformed that small size powder, large size powder, and epoxy resin were well dispersed in the green sheet.

• Educational Technology International
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• v.16 no.2
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• pp.231-247
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• 2015

The purpose of this study was to identify the factors of ICT literacy in the primary school students in South Korea and to examine the gender and city size difference on the factor of ICT literacy. To accomplish this goal, we have analyzed the data of Korea Youth Competency Measurement and International Comparative Study I: ICCS 2016 which is nationally collected from the primary school students, currently on the 5 ~ 6th grades in South Korea. 1,188 samples were used in the study excluding missing samples. The participants were 584 5^th grad and 604 6^th grad students, 620 males (52.2%) and 568 females (47.8%). The mean age was 13.49 years (SD=.52). The result of the study reveals the four factors of ICT literacy through cross-validating exploratory factor analysis and confirmative factor analysis; pleasure of using ICT, perceived usefulness of using ICT, learning ability with using ICT, and operating ability of ICT. This study found that the leaner differ in gender on learning ability with using ICT and pleasure of using ICT. The female students were significantly larger than male students on learning ability with using ICT. However, the male students were significantly larger than male students on pleasure of using ICT. This study found that the leaner differ in city size on the factors of ICT literacy excluding pleasure of using ICT. The students living in the big size city were significantly larger than the students living in the middle and small. That is, over all, female students were more learning with ICT, male students were more interesting about ICT, and the students living in the big size city were more ICT use for learning. Based on the results, some strategies were suggested on the proper use of the factors of ICT in education.

• Knowledge Management Research
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• v.16 no.3
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• pp.81-102
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• 2015

With the rapid development of digital media, there has been a huge change in a way of communication, a process of information diffusion and a role of traditional media. Not like mass media, social media enables users to generate and tap into the opinions of a larger world. From that reason, social media is impacting marketing strategies. However, still social media marketing researches just focus on case study, analysis of users motivation or analysis of power user's usage pattern. Word-of-mouth has always been important especially in marketing area. In social media, word-of-mouth depends on each user that's why this research focuses on individual user's activity in SNS. I defined 4 factors (produce, diffusion, network size, activity of network size enlarge) that are effect on activity and verified hypothesis by multiple regression analysis, hierarchical regression analysis and moderated multiple regression.

• Corrosion Science and Technology
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• v.14 no.6
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• pp.253-260
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• 2015

The pitting behaviours of 304L and 316L stainless steels were investigated at $3^{\circ}C$ to $90^{\circ}C$ in 1 M solutions of NaCl, NaBr and NaI by potentiodynamic polarization. The temperature dependences of the pitting potential varied according to the anion, being near linear in bromide but exponential in chloride. As a result, at low temperatures grades 304L and 316L steel are most susceptible to pitting by bromide ions, while at high temperatures both stainless steels were more susceptible to pitting by small chloride anions than the larger bromide and iodide. Thus, increasing temperature appears to favour attack by smaller anions. This paper will attempt to rationalise both of the above findings in terms of the point defect model. Initial findings are that qualitatively this approach can be reasonably successful, but not at the quantitative level, possibly due to insufficient data on the mechanical properties of thin passive films.

• Journal of information and communication convergence engineering
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• v.13 no.3
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• pp.189-196
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• 2015

In this paper, we present a rotating auto-zeroing offset cancellation technique, which can improve the performance of touch screen sensing circuits. Our target touch screen detection method employs multiple continuous sine waves to achieve a high speed for large touch screens. While conventional auto-zeroing schemes cannot handle such continuous signals properly, the proposed scheme does not suffer from switching noise and provides effective offset cancellation for continuous signals. Experimental results show that the proposed technique improves the signal-to-noise ratio by 14 dB compared to a conventional offset cancellation scheme. For the realistic simulation results, we used Cadence SPECTRE with an accurate TSP model and noise source. We also applied an asymmetric device size (10% MOS size mismatch) to the OP Amp design in order to measure the effectiveness of offset cancellation. We implemented the proposed circuit as part of a touch screen controller system-on-chip by using a Magnachip/SK Hynix 0.18-µm complementary metal-oxide semiconductor (CMOS) process.

• Journal of Forest and Environmental Science
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• v.31 no.1
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• pp.38-46
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• 2015

The stumpage price changes were calculated and analyzed from the data collected by Timber Mart-South from 1998 to 2007. We analyzed the relationship between pine sawtimber stumpage prices and timber sale characteristics using hedonic pricing method. Quadratic transformation was employed for sale size and contract length. Stumpage prices increased with sale size, contract length, bid sales, and the number of bidders. The presence of above average or excellent grade, market conditions, and logging conditions also are positively related to stumpage prices.

• Journal of the Korea Society of Computer and Information
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• v.20 no.7
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• pp.25-32
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• 2015

In this paper, we propose a license plate detection method of running cars in various road images. The proposed method first classifies the road image into day and night images to improve detection accuracy, and then the tail-light regions are detected by finding red color areas in RGB color space. The candidate regions of the license plate areas are detected by using symmetrical property, size, width and variance of the tail-light regions, and to find the license plate areas of the various sizes the morphological operations with adaptive size structuring elements are applied. Finally, the plate area is verified and confirmed with the geometrical and image features of the license plate areas. The proposed method was tested with the various road images and the detection rates (precisions) of 84.2% of day images and 87.4% of night images were achieved.