• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.4
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• pp.464-473
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• 2016

The air temperatures of the coast and inland are rising due to an increase in carbon dioxide emissions and abnormal climate phenomena caused by global warming, El Nino, La Nina and so on. The sea levels of the Earth are rising by approximately 2.0 mm per year (global average value) due to the thermal expansion of sea water, melting of glaciers and other causes by global warming. On the other hand, when it comes to designing a hydraulic structure or coastal hydraulic structure, the standard of the design water level is decided by analyzing four largeness tide values and a harmonic constant with the observed tidal water level or simulating numerical model. Therefore, the design tidal water level needs to consider an increasing speed of the seawater level, which corresponds to the design frequency. In the present study, the observed tidal water levels targeting 46 tidal stations operated by the Korea Hydrographic and Oceanographic Administration (KHOA) from the beginning of observations to 2015 per hour were collected. The variation of the monthly and yearly and increasing ratio were performed and divided into 7 seas, such as east and west part of the Southern Sea, south part and middle of the East Sea, south part and middle of the Western Sea, and Jeju Sea. The current study could be used to determine the cause of local seawater rises and reflect the design tidal water level as basic data.

• Korean Journal of Social Welfare
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• v.66 no.4
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• pp.53-75
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• 2014

The current status of Korean social work can be summarized as multiple complexities and ambiguities not only in ideological but in practical aspects. Although they have long been considered as an unique feature of social work as one of representative human service professions, the extent of such complexities are now reaching the culmination enough to raise the questions about the very nature of social work practice. This study aims to analyse such ambiguities and complexities around the field of social work in a systematic ways with the theory of liquid modernization, an creative framework for modern society, coined by Zygmunt Bauman who is now considered as one of the leading sociologist and thinker. The study shows clearly that social work in Korea is nowadays entering the phase of liquid modern society and specific features of liquidity of modern society such as consumerism, privatization, corruption of publicity etc are founded in the areas of social work. To make it worse, social work are thinking about the anachronical response to this flow of liquidity by selecting the strategies useful in solid modern era, not in the liquid one. In this context, the study suggests that social work practice have to prepare to adequate measures to secure its own autonomy and sustain genuine identification from the ruthless melting power of liquid modern society.

• Fire Science and Engineering
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• v.25 no.6
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• pp.83-88
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• 2011

This study presented the structure and characteristics of vinyl cords used for wiring electric equipment and appliances and analyzed the photographs of damaged flat-type vinyl cords (VFF, $1.25mm^2$) and the metallic cross-sectional structure of melted conductors. Normal VFFs were made by twisting several strands together and the surface of the conductor was red brown. In addition, from the analysis of the metallic structure of the conductor, it was found that its grains had been elongated. The surface of a VFF damaged by normal flame showed no sheen with carbonized insulation material fused on the conductor surface. In addition, from the analysis of the cross-sectional structure of the melted area, it was found that voids of a certain shape were formed on it but that the cord's own elongation structure could not be checked. The cross-sectional analysis of the melted conductor damaged by the external flame applied to a VFF to which electric current was being applied showed no elongation structure for each cord, and revealed that irregular voids and a columnar structure had grown. The surface of the VFF damaged by overcurrent was uniformly carbonized and the cross-sectional structure analysis of the melted conductor revealed that the dendritic structure had grown. The analysis of the characteristics of the VFF melted by short-circuit showed that even though some part of the surface was contaminated, it showed little sheen and that the area rebounded by melting was round in shape. In addition, the cross-sectional structure analysis using a metallurgical microscope showed the boundary surface and columnar structure and revealed an amorphous structure like normal copper at areas other than the melted conductor.

• Resources Recycling
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• v.18 no.1
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• pp.38-43
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• 2009

In this study, binderless consolidation processes of ultra foe Si powder, by-products of making high purity poly-Si in the current method, were systematically investigated for use as economical solar-grade feedstock. The average diameter of the silicon powder was $7.8{\mu}m$. The main contaminants of the fine silicon powder were $SiO_2$ type oxide and humidity. The chemical pretreatment using the HF solution was observed to be effective for the improvement of the compactability of the silicon powder and the density ratio and the strength of the silicon powder compacts. The yield of the binder-free consolidation process increased by 20% under a vacuum condition. In as-received state, the silicon powder were not pure enough to be used as solar grade feed-stock material. After the dry chemical treatments, a sufficiently high purity above solar-grade was able to be achieved.

• Journal of Welding and Joining
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• v.28 no.3
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• pp.92-98
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• 2010

Ferritic stainless steels, which have relatively small thermal expansion coefficient and excellent corrosion resistance, are increasingly being used in vehicle manufacturing, in order to increase the lifetime of exhaust manifold parts. But, there are limits on use because of the problem related to cosmetic resistance, corrosions of condensation and high temperature salt etc. So, Aluminum-coated stainless steel instead of ferritic stainless steel are utilized in these parts due to the improved properties. In this investigation, Al-8wt% Si alloy coated 409L ferritic stainless steel was used as the base metal during Gas Tungsten Arc(GTA) welding. The effects of coated layer on the microstructure and hardness were investigated. Full penetration was obtained, when the welding current was higher than 90A and the welding speed was lower than 0.52m/min. Grain size was the largest in fusion zone and decreased from near HAZ to base metal. As welding speed increased, grain size of fusion zone decreased, and there was no big change in HAZ. Hardness had a peak value in the fusion zone and decreased from the bond line to the base metal. The highest hardness in the fusion zone resulted from the fine re-precipitation of the coarse TiN and Ti(C, N) existed in the base metal during melting and solidification process and the presence of fine $Al_2O_3$ and $SiO_2$ formed by the migration of the elements, Al and Si, from the melted coating layer into the fusion zone.

• Journal of Plant Biotechnology
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• v.48 no.3
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• pp.131-138
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• 2021

We reviewed current research trends for discriminating between species of the Angelica genus, a group of important medicinal plants registered in South Korea, China, and Japan. Since the registered species for medicinal purposes differ by country, they are often adulterated as well as mixed in commercial markets. Several DNA technologies have been applied to distinguish between species. However, one of the restrictions is insufficient single-nucleotide polymorphisms (SNPs) within the target DNA fragments; in particular, among closely-related species. Recently, amplification refractory mutation system (ARMS)-PCR and highresolution melting (HRM) curve analysis techniques have been developed to solve such a problem. We applied both technologies, and found they were able to discriminate several lines of Angelica genus, including A. gigas Nakai, A. gigas Jiri, A. sinensis, A. acutiloba Kitag, and Levisticum officinale. Furthermore, although the ITS region differs only by one SNP between A. gigas Nakai and A. gigas Jiri, both HRM and ARMS-PCR techniques were powerful enough to discriminate between them. Since both A. gigas Nakai and A. gigas Jiri are native species to South Korea and are very closely related, they are difficult to discriminate by their morphological characteristics. For practical applications of these technologies, further research is necessary with various materials, such as dried or processed materials (jam, jelly, juice, medicinal decoctions, etc.) in commercial markets.

• Journal of the Korean earth science society
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• v.42 no.6
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• pp.717-733
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• 2021

This study is aimed to provide basic data to set the direction of polar literacy education and to raise awareness of the importance of polar research. Elementary, middle, and high school students' perception of the polar region was examined in terms of current status of polar information, impression regarding polar regions, and awareness of related issues. The study included 975 students from nine elementary, middle, and high schools, who responded to 16 questions, including close-ended and open-ended items. The results suggest that students had more experiences regarding the polar region on audiovisual media, but relatively limited learning experiences in school education. The impression they had of the polar region was confined to the monotonous image of a polar bear in crisis, following the melting of the glacier due to global warming. The students formed powerful images by combining scenes they saw in audiovisual media with emotions. In terms of recognizing problems in the polar region, the students were generally interested in creatures, natural environment, and climate change, but their interests varied depending on their school level and their own career path. The students highly valued the scientist's status as agents to address the problems facing the region, and gave priority to global citizenship values rather than practical standards. Based on the results, we suggest the following: introducing and systematizing content focusing on the polar region in the school curriculum, providing a differentiated learning experience through cooperation between scientists and educators, establishing polar literacy based on concepts that are relevant to various subjects, earth system-centered learning approach, setting the direction for follow-up studies and the need for science education that incorporates diverse values.

• Korean Journal of Food Science and Technology
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• v.37 no.3
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• pp.405-411
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• 2005

Chitosan, second largest biomass after cellulose on earth, has potential for use as functional food package due to its antibacterial activity. However, due to high melting temperature of chitosan, chitosan films have been made by casting method. Because gelatin has relatively low molting temperature depending upon amount of plasticizer added, it was added to chitosan to produce commercially feasible film. The objective of the current study was to determine optimum blend ratio and amount of chitosan/gelatin blend solutions against antibacterial activities for extruder resin. Gram-positive bacteria (Bacillus cereus ATCC 14579 and Listeria monocytogenes ATCC 15313) and -negative bacteria (Escherichia coli ATCC 25922 and Salmonella enteritidis IFO 3313) were used. Paper (8 mm) diffusion and optical density methods were used to evaluate effect of different blending ratio solutions on the inhibition of bacterial growth. Measured clear none size ranged from 8 mm to 18.07 mm in paper diffusion test. For B. cereus, E. coli, and S. enteritidis, addition of $50\;{\mu}L$ blend solution (chitosan/gelatin = 2/8: 0.3 mg) resulted in clear zone on paper disc. In L. monocytogenes, inhibition effect was observed with 0.6 mg chitosan (chitosan/gelatin=4/6). Minimum inhibitory concentration (MIC) values of B. cerues, L. monocytogenes, E. coli, and S. enteritidis with addition of chitosan were 0.1461, 0.2419, 0.0980, and 0.0490 mg/mL, respectively, These results indicate possibility of producing commercially feasible film with addition of optimum chitosan/gelatin amount.

• Journal of Animal Science and Technology
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• v.55 no.5
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• pp.451-460
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• 2013

The feed value of sesame meal, a main agricultural by-product from the northern area of Gyeongsangbuk-do province, was assessed in Hanwoo steers. A total of twelve Hanwoo steers (average BW = 412.08 kg) were allocated into a Control (fed no sesame meal) or Treatment (fed sesame meal from 14.6 months of age) group, considering BW and ages, and the animals were fed for a total of 480 days. The final BW, total gain and ADG for the Control and Treatment groups were 741.17 kg and 762.67 kg, 331.84 kg and 347.84 kg, and 0.69 kg and 0.72 kg, respectively, showing better performances in sesame meal-fed animals. Feed requirements during the whole experimental period improved by feeding sesame meal (15.31 and 14.87 for Control and Treatment group, respectively). Hanwoo steers fed sesame meal also showed a 22.83 kg heavier cold carcass weight (424.17 kg and 447.00 kg in the Control and Treatment group, respectively), and 2.41% improved dressing percentages (58.60% and 57.22% for the Control and Treatment group, respectively). The area of the M. longissimus dorsi was $91.83cm^2$ and $88.33cm^2$ in the Control and Treatment group, respectively. The final yield of A and B grade meat were 50 : 50% and 33.3 : 66.7% from the Control and Treatment group, respectively. The average marbling score was 4.83 and 5.50, and the numeric values for quality grade was 2.17 and 2.67 for the Control and Treatment group, respectively, showing better beef quality in sesame meal-fed Hanwoo steers. In fact, there were two animals with beef quality $1^{{+}{+}}$ in the sesame meal-fed group. The melting point of lipid extracted from the M. longissimus dorsi of Hanwoo steers was significantly (p<0.05) lower in the Treatment group ($28.28^{\circ}C$) compared to the Control group ($30.65^{\circ}C$). The composition of saturated fatty acids, $C_{14:0}$ (myristic acid) and $C_{16:0}$ (palmitic acid), were significantly lower in sesame meal-fed animals, 4.70% and 2.20% for myristic acid, and 30.55% and 27.12% for palmitic acid, in the Control and Treatment group, respectively. In contrast, there were no significant differences in C18:0 (stearic acid) composition between the groups. The composition of a representative unsaturated fatty acid, $C_{18:1}$ (oleic acid), was significantly higher in Treatment animals (49.89%) than Control animals (44.29%) (p<0.05). The ratio of total monounsaturated fatty acids / saturated fatty acids; M/S) was 1.10 and 1.36 for the Control and Treatment groups, respectively, showing remarkably higher ratios in sesame meal-fed group. The content of glutamic acid, related to beef flavor, was significantly higher in the Treatment group (3.35 mg/100 g) compared to the Control group (1.88 mg/100g) (p<0.05). The tenderness score, evaluated by an eight-point scale in the panel test, and overall palatability (based on juiciness, flavor, oiliness, and umami) were significantly higher in the Treatment group (5.67 and 5.23, respectively) than the Control group (3.83 and 4.60, respectively) (p<0.05). In conclusion, the current results imply that sesame meal could serve as a good supplement for Hanwoo steers for producing high quality beef.