• Journal of Ecology and Environment
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• v.39 no.1
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• pp.51-60
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• 2016

This study was conducted to examine litter fall, litter decomposition, and a short-term nutrient (C, N, P, K, Ca, and Mg) status for one year at various levels of basal area (21.4, 27.0, 30.8, 37.0, 42.1, and 46.7 m² ha^-1) in approximately 40-yearold red pine (Pinus densiflora S. et Z.) stands in the Hwangmaesan mountain forest in Korea. Monthly fluxes of litter fall components such as needles, broad leaves, branches, bark and total litter fall followed a similar pattern at various levels of basal area. Mean annual needle, bark and total litter fall fluxes were positively correlated with increased basal area (p<0.05), but the woody litter such as branches and cones was not correlated with basal area. Carbon and K concentrations of needle litter were negatively correlated with increased basal area, while nutrient (C, N, P, K, Ca, and Mg) fluxes were positively correlated with the basal area treatments. Remaining mass, N and P concentration and remaining N and P stocks in decomposing needle litter were not affected by the basal area. However, the concentration and stocks remaining of K, Ca, and Mg from decomposing litter were positively correlated with increased basal area during the initial three months of decomposition. The results indicate that basal area has an impact on nutrient cycles through change in litter fall and litter decomposition processes; thus, the dynamics of nutrient cycles based on a stand scale could differ considerably with different levels of basal area in red pine stands.

• Korean Journal of Soil Science and Fertilizer
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• v.24 no.4
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• pp.302-305
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• 1991

Six low-molecular-weight organic acids from decomposing plant residues were analyzed, which were formic, acetic, succinic, malic, tartaric, and citric acids. Straws of rice, barley, wheat, and rye were put under acid- hydrolysis after decomposition for different periods of time. The contents of organic acids in the hydrolysates were determined. 1. The relative molarity of a low-molecular-weight organic acid varies with the passage of the time of decomposition. 2. In general, formic and acetic acids were the major low-molecular-weight organic acids in all samples. 3. Malic acid was found to be only in a trace amount in rice and barley straws, and in their decomposed residues. 4. The relative molarities of total monocarboxylic acids(formic and acetic) increased with the progressing time of decomposition, far exceeding those of dicarboxylic and tricarboxylic acids combined together. 5. Formic and acetic acids were compensatory for each other and they were supposed to persist for a long time in soil environment.

• Korean Journal of Soil Science and Fertilizer
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• v.33 no.4
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• pp.302-309
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• 2000

These experiments have been conducted to study the effect by microbial inoculums currently on the market of enhancing the decomposition of organic matters. As a result of studying the effect of enhancing the decomposition of rice straw and chicken manure mixed with saw dust treated with commercial inoculums, it was found that the use of inoculums have speeded up the rate of decomposing straws at the early stage. The decomposition rate of rice straws that have speeded up with the use of comcrial inoculums in at early incubation periods has slow down in the later stage while the decomposition rate of chicken manure that has slowed down in the early stage has speeded up at the later incubation. As a result, it is found that there have been no differences between the use of microbial inoculums and control. In the experiment, filamentous fungus is found to have played an important role in decomposing the rice straws and bacteria is considered to have played a greater role in the decomposition of chicken manure mixed with saw dust.

• Journal of Korean Society of Forest Science
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• v.80 no.3
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• pp.303-310
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• 1991

Seasonal patterns of decomposition and nutrient release from the needle litter were examined using litter-bags in coastal Pinus thunbergii forests in nothern Kyushu, Japan. Dry matter losses from decomposing needle litter were smillar in all standsover a experimental period. Mass loss in dry weight is lost rapidly during the first year, and thereafter the rate of loss slows. Litter lost approximately 40% of initial mass in 1 yr. The predicted decay constant, k values ranged from 0.5 to 0.6 Decomposition half-times($t_{0.50}$) ranged from 1.1 to 1.4 year. In the decomposing needle litter, the concentrations of N and P generally increased with time while the concentration of K decreased. A decrease in absolute amount was noted for K during decomposition while in an increase was found for N. The order of mobility of elements was K>P>N. Mineralization phase of N had not appeared during the experiment.

• Journal of Mushroom
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• v.8 no.1
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• pp.1-5
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• 2010

The multiple functions of mushrooms are production of antibiotics, fodder for animal stock, organic fertilizers, food nutrients, favorite food, physiologically active materials, and decomposing organic matters, and cleaning environmental pollutants. Of these first three functions were evaluated. The value of the muti-functions of mushrooms were estimated to be 112 trillion 922 one hundred million Won, and if non-evaluated ones added the estimation would be doubled. This value is similar to multi-functions value of rice, 100 trillion Won. Especially, the industrial value of antibiotics from B-glucans is estimated to be 112 trillion Won, while animal stock fodder value is 618 one hundred million Won, organic fertilizer 56 one hundred million Won and decomposer of ecology 360 one hundred million Won.

• Journal for History of Mathematics
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• v.21 no.4
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• pp.153-168
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• 2008

This study investigates how high achievers solve a given mathematical problem. The problem, which comes from 'SanHakIbMun', a Korean mathematics book from eighteenth century, is not used in regular courses of study. It requires students to determine the area of a gnomon given four dimensions(4,14,4,22). The subjects are 84 sixth grade elementary school students who, at the recommendation of his/her school principal, participated in the mathematics competition held by J university. The methods used by these students can be classified into two approaches: numerical and decomposing-reconstructing, which are subdivided into three and six methods respectively. Of special note are a method which assumes algebraic feature, and some methods which appear in the history of eastern mathematics. Based on the result, we may observe a great variance in methods used, despite the fact that nearly half of the subject group used the numerical approach.

• 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 Forest and Environmental Science
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• v.38 no.1
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• pp.48-54
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• 2022

This study was conducted to examine litter inputs and litter decomposition rates following thinning, which is among the most important forest management activities that enhance the beneficial functions in Korean forests. Litter inputs and litter decomposition rates following a 2-year elapse from thinning in Pinus densiflora and following a 7-year elapse from thinning in Quercus variabilis stands were measured for 2 years from 16 sites in three regions (Sancheong-gun, Uiryeong-gun, and Jinju-si) in Gyeongsangnam-do, Korea. Annual needle litter inputs in P. densiflora stands were significantly decreased following thinning, whereas annual broadleaved leaf litter inputs in Q. variabilis stands were not significantly different between thinned and unthinned treatments. The annual mean total litter inputs in both tree species were significantly lower in the thinned (P. densiflora: 3,653 kg ha^-1 year^-1; Q. variabilis: 4,963 kg ha^-1 year^-1) compared to the unthinned stands (P. densiflora: 5,138 kg ha^-1 year^-1; Q. variabilis: 5,997 kg ha^-1 year^-1) during the study period. The mass loss rates from decomposing needle litter in P. densiflora stands were significantly lower (p<0.05) in the thinned stands than in the unthinned stands for two sampling dates of the eight included in the study, whereas the decomposition rates from decomposing leaf litter in Q. variabilis stands were not affected by thinning. The results indicate that thinning effects on total litter inputs remained clear following a 2-year elapse from thinning in P. densiflora stands and following a 7-year elapse from thinning in Q. variabilis stands.

• Animal Bioscience
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• v.36 no.9
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• pp.1453-1464
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• 2023

Objective: This study investigated the changes in bacterial communities within decomposing swine microcosms, comparing soil with or without intact microbial communities, and under aerobic and anaerobic conditions. Methods: The experimental microcosms consisted of four conditions: UA, unsterilized soil-aerobic condition; SA, sterilized soil-aerobic condition; UAn, unsterilized soil-anaerobic condition; and San, sterilized soil-anaerobic condition. The microcosms were prepared by mixing 112.5 g of soil and 37.5 g of ground carcass, which were then placed in sterile containers. The carcass-soil mixture was sampled at day 0, 5, 10, 30, and 60 of decomposition, and the bacterial communities that formed during carcass decomposition were assessed using Illumina MiSeq sequencing of the 16S rRNA gene. Results: A total of 1,687 amplicon sequence variants representing 22 phyla and 805 genera were identified in the microcosms. The Chao1 and Shannon diversity indices varied in between microcosms at each period (p<0.05). Metagenomic analysis showed variation in the taxa composition across the burial microcosms during decomposition, with Firmicutes being the dominant phylum, followed by Proteobacteria. At the genus level, Bacillus and Clostridium were the main genera within Firmicutes. Functional prediction revealed that the most abundant Kyoto encyclopedia of genes and genomes metabolic functions were carbohydrate and amino acid metabolisms. Conclusion: This study demonstrated a higher bacteria diversity in UA and UAn microcosms than in SA and SAn microcosms. In addition, the taxonomic composition of the microbial community also exhibited changes, highlighting the impact of soil sterilization and oxygen on carcass decomposition. Furthermore, this study provided insights into the microbial communities associated with decomposing swine carcasses in microcosm.

• The Korean Journal of Ecology
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• v.27 no.3
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• pp.165-171
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• 2004

Weight loss and nutrients dynamics during decomposition of oak roots (diameter classes: R₁〈0.2㎝, 0.5㎝〈R₂〈1㎝, 1㎝〈R₃〈2㎝, 2㎝.〈R₄〈4㎝) (Quercus acutissima) were studied for 33-months in Kongiu, Korea. After 33-months, decomposition rate of R₁, R₂, R₃ and R₄ was 49.6%, 47.5%, 66.4% and 66.1%, respectively. The decomposition constant(k) for R₁, R₂, R₃, and R₄ was 0.249/yr, 0.234/yr, 0.397/yr and 0.393/yr, respectively. Larger diameter class of the root lost more weight than smaller diameter class. N concentration in decomposing oak roots increased in all diameter classes. After 33-months, remaining N in R₁, R₂, R₃ and R₄ was 66.5%, 80.7%, 84.4% and 44.4%, respectively. K concentration in decomposing oak roots decreased in early part of decomposition and then increased in later stage of decomposition. After 33-months, remaining P in R₁, R₂, R₃ and R₄ was 64.7%, 62.4%, 93.1% and 30.7%, respectively. K concentration in decomposing oak roots decreased rapidly in early stage of decomposition. Remaining K in R₁, R₂, R₃ and R₄ was 11.6%, 10.6%, 5.9% and 7.7%, respectively. Ca concentration in decomposing oak roots showed different among diameter classes. After 33-months, remaining Ca in R₁, R₂, R₃ and R₄ was 66.2%, 51.0%, 39.1% and 48.3%, respectively. Initial concentration of Mg in oak root was higher in smaller diameter class. After 33-months, remaining Mg in R₁, R₂, R₃ and R₄ was 15.3%, 29.9%, 24.5% and 69.4%, respectively.