• The Transactions of the Korean Institute of Power Electronics
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• v.15 no.2
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• pp.111-118
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• 2010

Recently, LCD TV using LED backlight has a great attention due to its low power consumption, slim construction, mercury free, wide color gamut and fast response. For the uniform brightness of the LCD panel, multi channel LEDs and DC/DC converter for each LED are required in conventional system. Therefore energy conversion efficiency is poor, the system size bulky and the cost of production high. To overcome these above mentioned drawbacks, a new current-balancing multi-channel LED driver is proposed in this paper. It can not only drive multi-channel LEDs with one DC/DC converter but also provide all LEDs with constant balanced current. To confirm the validity of the proposed driver, its operation and performance are verified on a prototype for 46" LCD TV.

• Journal of Digital Convergence
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• v.17 no.9
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• pp.399-406
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• 2019

The purpose of this study is to examine the relationship between corporate reputation and the profitability. In this study, Big Data Analysis was conducted for Hyundai Motor, Shinsegae Department Store, SK Telecom, and Amorepacific to solve research problems. The results of this study show that the effect of each corporate reputation on the profitability is different according to the company. For products such as Hyundai Motor and Amorepacific that are used directly by consumers, the corporate reputation formed by the comments was more influential. In addition, distribution Service company such as Shinsegae Department Store showed more influence by online news. On the other hand, SK Telecom did not have a significant effect on profitability. Based on the results, this study emphasizes the importance of online news and comments on corporate reputation management, and aims to contribute to establishing an efficient reputation management strategy by examining the relationship between corporate reputation and profitability.

• Journal of the Korean Electrochemical Society
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• v.24 no.4
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• pp.113-119
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• 2021

In this study, impurity free V^3.5+ electrolytes were prepared using formic acid as a reducing agent and PtD/C as a catalyst and it was applied to VRFB. The well-oriented 3D dendrite structure of the PtD/C catalyst showed high catalytic activity in formic acid oxidation reaction and vanadium reduction reaction. As a result, the conversion ratio of electrolyte using the PtD/C was 2.73 mol g^-1 h^-1, which was higher than that of 1.67 mol g^-1 h^-1 of Pt/C prepared by the polyol method. In addition, in the VRFB charging and discharging experiment, the V^3.5+ electrolyte produced by the catalytic reaction showed the same performance as the standard V^3.5+ electrolyte prepared by the electrolytic method, thus proving that it can be used as an electrolyte for VRFB.

• Journal of The Korean Association of Information Education
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• v.25 no.6
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• pp.987-994
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• 2021

Computational Thinking is an analytical thinking ability that is necessary for everyone and everywhere. The existing Computational Thinking development education provided in Practical textbooks leads to block-based programming languages from unplugged activities. Many unplugged activities focus on practicing sequential order, which may lack the learning of abstractions or automation concepts. In block-based programming languages, concepts such as coordinate planes, which are not introduced in elementary school curriculum, appear, making students feel burdened by the block-based programming language itself. In this study, a curriculum was designed for elementary student's computational thinking through game-based programming language education. The results and their effectiveness were analyzed through the beaver challenge. As a result of analyzing the pre-test and post-test scores, it was confirmed that students' computational thinking skills improved.

• Clean Technology
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• v.16 no.2
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• pp.95-102
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• 2010

Sulfonic acid (-SO3H) functionalized mesoporous silica containing HMS, SBA 15(S15), MCM 41(M41) were synthesized by post-synthesis and co-condensation method. Their catalytic performance is tested by dehydration reaction of D-xylose to furfural. As a result, good conversion and selectivity was obtained using water as an environmentally friendly solvent. Additionally, increased amounts of sulfuric acid in catalysts resulted in improved conversion of D-xylose. All of the acid-functionalized mesoporous silica showed higher selectivity than other solid acids such as ${\gamma}-Al_{2}O_{3}$ and zeolite.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2021.05a
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• pp.123-125
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• 2021

Pregnant women's psychological health affects the health of the fetus. Therefore, health care for pregnant women is essential for a healthy fetus. One of the symptoms of pregnancy among many pregnant women is the depression of emotional ups and downs. One way to relieve this depression is to use light therapy and color therapy by using lighting. Adjust the color temperature of the light so that it affects the emotions through color. For example, ceiling lights in car dealerships are set up like a sun-light, or low color temperature are used to create a comfortable mood in facilities like spas. In this paper, we use image sensors to identify the psychological state and change the color temperature of the lighting in real time. The study was conducted to relieve postpartum depression by using the psychological effects of pregnant women with easily purchased lighting devices.

• Design Convergence Study
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• v.13 no.5
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• pp.131-145
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• 2014

Considering the number of population commuting from Gyeonggi to Seoul, the development of the bus system is relatively slow. There are many problems to be solved but it has been overlooked, leaving the users in discomfort. The goal of this research is to improve the current system to satisfy the unmet needs, using HCI methods, which is composed of five steps, including Define, Find, Analyze & Synthesize, Ideation, Develop. In Define, we recruited the interviewees using the extreme user method to find their needs. In Find, we proceeded 'be the customer', shadowing for background research and in-depth interview. In Analyze & Synthesis, we analyzed the customer needs and clustered to similar needs to draw useful ideas. After that we suggested sophisticated ideas based on design principles from previous stage and visualized in user scenarios and mock-ups. Overall, the research suggests with text message service, informative light service and mobile application to improve the existing bus station.

• Korean Journal of Soil Science and Fertilizer
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• v.37 no.2
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• pp.116-123
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• 2004

This study was conducted to investigate the changes in physicochemical and microbiological properties during fermenting process of organic fertilizer which was made from the mixture of organic materials such as sesame oil cake, fish meal, blood meal, rice bran, ground bone meal, and natural minerals such as illite, crusted oyster shell and loess. They were mixed and fermented for 70 days. The sesame oil cake and rice bran, major ingredients for organic fertilizers, consisted of 7.6 and 2.6% total nitrogen, 3.6 and 4.6% $P_2O_5$, 1.4 and 2.2% $K_2O$, respectively. The ground bone meal included 29.2% $P_2O_5$ and illite included 3.8% $K_2O$. Temperature of organic fertilizer during the fermentation rapidly increased over $50^{\circ}C$ within 2 days after mixing and stabilized similar to outdoor temperature after 40 days. Moisture content decreased from 36.3 to 16.0% after 1 month. C/N ratio of organic fertilizer slightly increased until 30 days and thereafter, it slowly decreased, It resulted from the faster decrease of total nitrogen concentration compared with organic matter. Concentration of $NH_4-N$ in organic fertilizer rapidly increased from 1,504 to $5,530mg\;kg^{-1}$, the highest concentration after 10 days. Meantime, $NO_3-N$ concentration was low and constant about $150mg\;kg^{-1}$ over the whole fermenting period. This result seemed to be due to the high pH. The organic ferfilizer fermented for 70 days was composed of 2.7% N, 2.8% $P_2O_5$, 1.8% $K_2O$, and 35.9% organic matter. Total populations of aerobic bacteria, Bacillus sp. and actinomycetes, after fermenting process, were $12.5{\times}10^{10}$, $45.5{\times}10^{5}$ and $13.6{\times}10^{5}cfu\;g^{-1}$ respectively. Pseudomonas sp. was $71.9{\times}10^{7}cfu\;g^{-1}$ at first, but it rapidly decreased according to the rise of temperature. Yeasts played an important role in the early stage of fermentation and molds did in the late stage.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.20 no.1
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• pp.49-59
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• 1984

Optimizing investigation of characteristics of underwater welding by a gravity type arc welding process was experimentally carried out by using six types of domestic coated welding electrodes for welding of domestic marine structural steel plates (KR Grade A-1, SWS41A, SWS41B,) in order to develop the underwater welding techniques in practical use. Main results obtained are summarized as follows: 1. The absorption speed of the coating of domestic coated lime titania type welding-electrode became constant at about 60 minutes in water and it was about 0.18%/min during initial 8 minutes of absorption time. 2. Thus, the immediate welding electrode could be used in underwater welding for such a short time in comparison with the joint strength of in-atmosphere-and on-water-welding by dry-, wet-or immediate-welding-electrode. 3. By bead appearance and X-ray inspection, ilmenite, limetitania and high titanium oxide types of electrodes were found better for underwater-welding of 10 mm KR Grade A-1 steel plates, while proper welding angle, current and electrode diameter were 6$0^{\circ}C$, above 160A and 4mm respectively under 28cm/min of welding speed. 4. The weld metal tensile strength or proof stress of underwater-welded-joints has a quadratic relationship with the heat input, and the optimal heat input zone is about 13 to 15KJ/cm for 10mm SWS41A steel plates, resulting from consideration upon both joint efficiency of above-100% and recovery of impact strength and strain. Meanwhile, the optimal heat input zone resulting from tension-tension fatigue limit above the base metal's of SWS41A plates is 16 to 19KJ/cm. Reliability of all the empirical equations reveals 95% confidence level. 6. The microstructure of the underwater welds of SES41A welded in such a zone has no weld defects such as hydrogen brittleness with supreme high hardness, since the HAZ-bond boundary area adjacent to both surface and base metal has only Hv400 max with the microstructure of fine martensite, bainite, pearlite and small amount of ferrite.

• Cartoon and Animation Studies
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• s.41
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• pp.553-578
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• 2015

The Korean society was forcefully merged with the invasion of Japan in 20th century, and traditional culture of Korea was damaged severely by colonization from Japan. After liberation, Korean society experienced drastic social change with Korean War, and industrial economy and democratic system developed as modernization and democratization occurred. However, Korean traditional culture dissolved more severely as Korean society developed industrial economy and democracy. As criticism of existing Western center of society and the emphasis of cultural identity of non-western regions and third-world, world society preferred exchange of culture of diverse nations and people with each other in advent of postmodernism thoughts in mid-late 20th century. If the cultural identity of Korea was dissolving meanwhile, it was needed to be recovered again. Despite the research in Korean history, language, art, architecture was performed to recover cultural identity of Korea, it did not go in-depth with Korean mythology, for Korean mythology is considered as superstition or savage. Mythology shows subconscious group psychology of people who live in certain specific region. Studying Korean mythology is one of the ways to rediscover cultural identity of Korea. In order for Korean mythology to be known to many people, its stories should be told by media. There were movies, plays, drama, and novels produced based on existing Korean mythology as introduction, then these mythical stories are appear in subculture contents such as recent comics, animation, webtoon, games, and light novels. Then population of game players and webtoon readers increased as dissemination of PC and smart phones, and increasing market scale of subculture contents increased a population of consumers of comics, animation, and light novel. Consumers of sub-culture contents were interested as many of these contents were created, base on Korean mythology. Therefore, this paper is written as research on Korean mythology and its signification in sub-cultural contents which were produced base on Korean mythology.