• Composites Research
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• v.33 no.6
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• pp.346-352
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• 2020

In mobility industries, the use of thermoplastic composites increased dynamically. In this study, the mechanical and impregnation properties of continuous glass fiber (GF)/polypropylene (PP) composite were evaluated with different GF contents. The GF/PP commingled fiber was manufactured with different GF contents and continuous GF/PP composite was manufactured using continuous compression molding process. Tensile, flexural, and impact test of specimens were evaluated with different GF contents. The fracture behavior of specimens was proved using field emission-scanning electron microscope images of fracture area and impregnation property was evaluated using dynamic mechanical analyzer and interlaminar shear strength. Finally, the GF/PP composite was the optimized mechanical and impregnation properties using 50 wt.% GF/PP commingled fiber.

• Journal of the Korea Organic Resources Recycling Association
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• v.29 no.1
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• pp.37-46
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• 2021

Nitrogen and phosphorus in livestock manure are environmental pollutants, but also could be valuable industrial resources. In the present study, we (1) introduced various nitrogen removal technologies such as stripping, thermal method, membrane, and electrodialysis, (2) reviewed relevant studies reported in 2011-2020, in particular, full-scale experiences, and (3) assessed each technologies based on the above survey results. In addition, we provided the information on the appropriate range of the pH, temperature, gas and liquid ratio, and so on in ammonia stripping process, and expected mass balance when it is connected to biogasification process. We hope the content herein can be helpful for making policy and operating full-scale plant in Korea.

• Journal of Ecology and Environment
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• v.45 no.4
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• pp.264-276
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• 2021

Background: Salt marshes provide a variety of ecosystem services; however, they are vulnerable to human activity, water level fluctuations, and climate change. Analyses of the relationships between plant communities and environmental conditions in salt marshes are expected to provide useful information for the prediction of changes during climate change. In this study, relationships between the current vegetation structure and environmental factors were evaluated in the tidal flat at the southern tip of Ganghwa, Korea, where salt marshes are well-developed. Results: The vegetation structure in Ganghwa salt marshes was divided into three groups by cluster analysis: group A, dominated by Phragmites communis; group B, dominated by Suaeda japonica; and group C, dominated by other taxa. As determined by PERMANOVA, the groups showed significant differences with respect to altitude, soil moisture, soil organic matter, salinity, sand, clay, and silt ratios. A canonical correspondence analysis based on the percent cover of each species in the quadrats showed that the proportion of sand increased as the altitude increased and S. japonica appeared in soil with a relatively high silt proportion, while P. communis was distributed in soil with low salinity. Conclusions: The distributions of three halophyte groups differed depending on the altitude, soil moisture, salinity, and soil organic matter, sand, silt, and clay contents. Pioneer species, such as S. japonica, appeared in soil with a relatively high silt content. The P. communis community survived under a wider range of soil textures than previously reported in the literature; the species was distributed in soils with relatively low salinity, with a range expansion toward the sea in areas with freshwater influx. The observed spatial distribution patterns may provide a basis for conservation under declining salt marshes.

• Korean Journal of Agricultural Science
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• v.49 no.3
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• pp.571-582
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• 2022

Cacao, a major ingredient for making chocolate, has been shown to have potent antioxidant effects. The consumption of raw cacao has beneficial effects on health. This study determined the fermentation properties of yoghurt that was manufactured with cacao nibs (Theobroma cacao L.). The pH of the yogurt containing the cacao nibs was lower than that of the control, and this reduction was both concentration and fermentation time-dependent. Furthermore, the number of lactic acid bacteria in the yogurt made with cacao and its viscosity increased in a cacao nibs dependent manner. In particular, the yoghurt with 5% cacao nibs added had the highest number of lactic acid bacteria at 48 hours at the end point of the fermentation. Whey protein degradation in yogurt containing cacao nibs increased with the fermentation time, and the organic acid production, especially lactic acid, in the yogurt containing cacao nibs increased significantly after 16 hours of fermentation. In addition, the total polyphenol content of the yogurt containing cacao nibs increased, which was proportional to the amount added. Sensory evaluations of the yogurts indicated that overall taste was less desirable as cacao nib loadings increased from 1 to 5% compared with controls. This result is due to the excessive acidity, which was strongly perceived in the absence of added sugar. The development of yogurts with cacao nibs is expected to contribute much to the appeal of fermented milk.

• Korean Journal of Agricultural Science
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• v.49 no.2
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• pp.215-226
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• 2022

This study aims to investigate the soil environment characteristics of the Abies koreana community, which is currently showing a continuous decline in its size, in order to provide fundamental data for the management and creation of a conservation plan for the Abies koreana communities at the Korean national parks of Sobaeksan, Deogyusan, and Jirisan. Soil depth investigations were conducted at depths deeper than 40 cm into the B horizon at most study sites, except for the Dwaejipyeongjeon and Byeoksoryeong sites. The soil water content exceeded 30% on average, and these soils showed low bulk density levels. The soil texture was found to be the loamy or silty loam type at most study sites. It was also found in a chemical characteristic assessment that the soil samples contained more than 10% organic matter at most study sites. The cation exchange capacity (C.E.C.) and total N concentration levels were also high at most study sites. However, the soil showed low exchangeable K⁺, Na⁺, Ca²⁺, and Mg²⁺ levels at most study sites. Finally, the pH values were 4.90, 4.53, and 4.60 at soil depths of 10 cm at the Sobaeksan, Deogyusan and Jirisan sites, respectively, outcomes that are notably lower than the average levels in soil from Korean forests according to the literature. This appears to be due to the cold and wet climate of these subalpine regions given the reduced leaf-litter decomposition rate and accumulation of organic acids.

• Clean Technology
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• v.16 no.4
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• pp.245-253
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• 2010

Optimum conditions for UV-radiated photopolymerization of unsaturated polyester that could be used as protecting layer of large diameter pipe were investigated in this paper. UV photopolymerization method was selected to solve the problems, arising when thermal polymerization by organic peroxide was used, such as the instability of peroxide initiator, the evolution of volatile organic compound, and thermal deformation of product. Two of the photo-initiators (Irgacure 819 and Darocure 1173) well known for its penetrating ability deep into the polymer layer were selected, and the optimum conditions for photopolymerization (1.5 phr initiator content, 1:1.2 initiator ratio, Ga lamp for UV source) were found from the thermal and mechanical test results of the resultant UP polymers. In addition, composite materials containing UP polymer and glass fiber were tested for hardness, impact strength, and flexural strength to find that the impact strength of composite significantly improved.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.12 no.3
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• pp.239-243
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• 2007

Presence of bottom water nitrite in the Ulleung Basin was remarkable because it is totally unexpected phenomenon at such an oxygen-rich environment. Yet no scientific explanation was set forward. Of several plausible explanations, following the Ockham's suggestion, a leaching of nitrite as an intermediate product of denitrification in the top sediment at the slope is most agreeable to given environmental settings. There seems no complementary process to make up the loss of N in the Ulleung Basin, which seems contribute to the characteristically low N:P ratio in the deep waters. If warming proceeds that weakens the thermohaline circulation, a current biological pump may stall and the phytoplankton assemblage might replaced drastically. If so this will pause an utmost challenge to the ecosystem of the East/Japan Sea. Still there remains a contradictory sedimentary signature that requests further explanation regarding the N (or organic C)-cycle such as extraordinarily high organic carbon content despite abundant oxidants in the overlying waters.

• Journal of the Korea Organic Resources Recycling Association
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• v.17 no.4
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• pp.29-35
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• 2009

Pyrolysis is recently used as one of alternative methods of animal waste treatment. In this study bio-oil was produced at $550^{\circ}C$ in an auger reactor through pyrolysis process. Two pig waste mixtures were used, pig feces mixed with rice husks and pig feces mixed with sawdust. The main compositions of hemicellulose, lignin, cellulose, protein, and fat were analyzed chemically. Based on the main composition results obtained, the contents of holocellulose (the sum of hemicellulose and cellulose) and lignin had a significant positive effect on bio-oil production, and there was a significant negative effect of ash content on bio-oil yield. The interactions between the different feedstocks were evaluated, and it was concluded that the interaction between pig feces and rice husks was minimal, whereas the interaction between pig feces and sawdust was significant.

• Journal of the Korea Organic Resources Recycling Association
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• v.18 no.2
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• pp.84-92
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• 2010

This research was conducted to investigate physico-chemical characteristics of municipal solid waste (MSW) generated from T City, Gangwon-do and leaching characteristics of the incineration ash. From the results, bulk density of MSW in T city was $231kg/m^3$. Combustible and incombustible components were in 94.0% and 6.0%, respectively. Food waste and papers in combustible component occupied 32.3% and 41.2%. Water, volatile solids, and ash content were 41.3%, 50.5%, and 8.2%. C, H, O, N, S, and Cl showed 51.4%, 6.3%, 26.7%, 1.1%, 0.2%, 0.5%, respectively. Low heating value (2,704 kcal/kg) of T city was similar to 2,764 kcal/kg of Chuncheon and was 1,000 kcal/kg higher than 1,467~1,584 kcal/kg of the past Kuro-gu and Koyang city. The specification of leaching characteristics of the incineration ash were within the Korean regulation standard.

• Culinary science and hospitality research
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• v.21 no.6
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• pp.103-119
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• 2015

This study was carried out to evaluate the quality of characteristics of Takju, Yakju, and spirit made from Bunkuk(flour), Phellinus linteus and Ginger kuk. The sacharogenic power of Nuruks and pH, brix, acidity, cell numbers of yeast, and alcohol content of Deotsuls were analysed; flavors, organic acids, and sensory evaluation of Takju, Yakju, and spirit were employed in the analysis of this current study. Results showed that the saccharogenic power of Phellinus linteus kuk after fermentation of Nuruks showed the highest level, and Phellinus linteus kuk and Ginger kuk showed the same level after dry Nuruks. During fermentation of Deotsuls, pH and brix decreased with increased fermentation time, while acidity increased with increased fermentation time. Cell numbers of yeast were found to be at the highest level in Phellinus linteus kuk on the first day of fermentation, and it was the same result in the final stage(p<0.05). Alcohol content increased with an increase in fermentation time, and showed no significant difference between control and test in the final stage of fermentation. In terms of analysis of flavor components, acetone and n-amyl alcohol were not detected in Takju, Yakju, and spirit. n-butanol was detected at the highest value, followed by i-amyl alcohol. Fusel oil was detected at the highest level in spirit fermented by Bunkuk. In analysis of organic acids, lactic acid showed the highest content followed by acetic acid. Very small amounts of acetic acid were detected in the spirit and other organic acids were not detected. In sensory evaluation, Takju, Yakju, and spirit made from Phellinus linteus kuk showed the highest score. As a result of this study, Phellinus linteus kuk presented the most desirable Nuruk in order to make Takju, Yakju, and spirit.