• Korean Journal of Organic Agriculture
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• v.19 no.spc
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• pp.119-122
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• 2011

Among the developed bio-degradable polymer films as compared with transparent film(White), black polymer film was significantly more effective for controlling weeds in red pepper. Also, we found that white and black polymer mulching had 81.8% and 97.9% of managing weed controlling effects in rice, respectively. Compared to non-mulched rice paddy with water supply, the non-mulched rice paddy without any water supply has stopped its growth at 41 days after transplanting, while polymer-mulched rice paddy without water supply had about 60% of normally growing rice plants. This shows the polymer treatment has a remarkable effect on water and power saving, solution of herbicidal resistance, avoidance of herbicidal influence to eco-system etc. When the naturally decomposing polymer was used, a temperature was elevated as high as $4.7^{\circ}C$ on maximum and $2.6^{\circ}C$ on average. Also the naturally decomposing polymer accelerated rooting by 7 days and lowered a stress level from transplanting. The weed control effect mulched by polymer was remarkable as 98.7%. The polymer now, after 294 days treated on the rice paddy, has been completely decomposed.

• Journal of the Korea Society of Computer and Information
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• v.27 no.3
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• pp.79-90
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• 2022

'Trust' is 'believing and relying on people or things', and at the same time, it is the foundation and essential condition of existence of a specific community or society. How blockchain technology creates trust can be found in the fact that it is a technology shared by all participants. As a shared technology, blockchain itself shows three characteristics: transparency, immutability, and availability. Because it is shared, it is transparent, and because it is shared, it is immutable, which is difficult to modify or delete. In addition, since it is shared, the entire system operates normally even if some failure occurs. The significance of trust created based on this blockchain technology can be summarized in three aspects as follows. The first is to understand the problem of trust in connection with technology. Second, understanding the relationship between information and trust begins to pay attention. Third, based on the expanded information processing capability, it is possible to establish a large-scale, concrete relationship without central mediation.

• Journal of Korea Port Economic Association
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• v.37 no.4
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• pp.41-50
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• 2021

This study investigated what the general public thinks about the shipping industry and how important it is. As a result of the study, more than half of the respondents answered that they knew a little about the shipping industry or that they were normally knew about the shipping industry. Regarding the necessity of budget input to prevent bankruptcy of national shipping companies, it was found that more than half of the respondents answered that it was necessary or moderate. Regarding the necessity of maintaining a national shipping companies, 53% of respondents said it was necessary, and 23% of respondetns said it was normal. However, when asked if they thought that maintaining a national shipping companies would benefit me and my family, 39% of respondetns answered "normal" and 28% of respondetns answered "mostly". As for the cause of Hanjin Shipping's bankruptcy, 49% of respondents said that the owners' family members were immoral and incompetent, and 17.4% of respondetns said that the shipping market conditions deteriorated. Regarding the necessity of fostering the shipping industry, foreign currency acquisition and service balance improvement through export of shipping services accounted for 43.5%, and smooth transportation of import and export cargo accounted for 36.5%. When asked what kind of damage I suffered from Hajin Shipping's bankruptcy, 54.6% answered other (not much), and 14.5% said inflation. Abouve these results, this study gave implication in terms of public promotion and transparent business management.

• Restorative Dentistry and Endodontics
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• v.30 no.3
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• pp.178-183
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• 2005

This study was done to evaluate whether vital bleaching agents could influence on the translucency of the bovine enamel. The anterior bovine teeth that were extracted one day before and without any gross discoloration were obtained and then were preserved in physiologic saline. 6 mm cylindrical tooth specimens were fabricated with diamond puncher perpendicularly on labial surface of bovine tooth. After embedded in transparent acrylic resin with labial surface being exposed, they were cut to a thickness of 1.2 mm with low speed diamond saw (Isomat, Buehler Co., Lake Bluff, IL, USA). They were smoothly ground to 1 mm thickness of enamel with sandpaper. 24 specimens were randomly divided into 3 groups and control group respectively. Opalescence (10% carbamide peroxide, Ultradent, South Jordan, USA), Rembrandt (10% carbamide peroxide, DenMat, USA) and Opalescence F (15% carbamide peroxide with fluoride, Ultradent, USA) were applied on labial sides of the bovine enamel for 7 days (bleaching agents were reapplied every 24 hours) and the opposite surface was contacted to cotton that soaked in distilled water. The control group was soaked in distilled water. Three stimulus value X, Y and Z were evaluated with colorimeter (Color ' Color Differencerneter, Model TC-6FX, Tokyo Denshoku Co., Japan) on the labial surface of all specimen three times on white and black background plate before the bleaching agents were applied and on 3rd, 5th and 7th day after applied. The degree of translucency was normally assessed by measuring the inverse property, opacity (contrast ratio). 10% Opalescence, 15% Opalescence-F, and control group showed no significant variation in the translucency of bovine enamel, However Rembrandt decreased the translucency of it (p < 0.01).