• Journal of the Korea Society of Computer and Information
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• v.28 no.1
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• pp.121-127
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• 2023

In this study, the design conditions and CFD analysis results are compared and reviewed in SCR that can optimally reduce nitrogen compounds. To this end, it was analyzed and compared using CFD to see if the design criteria were satisfied for the shell and tube areas of the boiler. In the SCR system, the analysis area is the gas/air heat exchanger on the shell side, and eight tubes of the gas/air heat exchanger on the tube side. Through CFD analysis, the gas velocity distribution on the primary catalyst side of the SCR system was designed to be 2.4%, and the NH3/NOx molar ratio distribution was 3.7%, which satisfied the design criteria. In addition, the uniformity of the temperature distribution was confirmed and the required condition of 260℃ or higher was satisfied. The angle of the gas entering the catalyst met the design conditions at 2.9 degrees, and the pressure loss that occurred also satisfied the design requirements. Through this CFD analysis, it was confirmed that it was designed and operated by satisfying the design conditions required for each area.

• Journal of Microbiology and Biotechnology
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• v.32 no.12
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• pp.1527-1536
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• 2022

Escherichia coli can use allantoin as its sole nitrogen source under anaerobic conditions. The ureidoglycolate produced by double release of ammonia from allantoin can flow into either the glyoxylate shunt or further catabolic transcarbamoylation. Although the former pathway is well studied, the genes of the latter (catabolic) pathway are not known. In the catabolic pathway, ureidoglycolate is finally converted to carbamoyl phosphate (CP) and oxamate, and then CP is dephosphorylated to carbamate by a catabolic carbamate kinase (CK), whereby ATP is formed. We identified the ybcF gene in a gene cluster containing fdrA-ylbE-ylbF-ybcF that is located downstream of the allDCE-operon. Reverse transcription PCR of total mRNA confirmed that the genes fdrA, ylbE, ylbF, and ybcF are co-transcribed. Deletion of ybcF caused only a slight increase in metabolic flow into the glyoxylate pathway, probably because CP was used to de novo synthesize pyrimidine and arginine. The activity of the catabolic CK was analyzed using purified YbcF protein. The V_max is 1.82 U/mg YbcF for CP and 1.94 U/mg YbcF for ADP, and the K_M value is 0.47 mM for CP and 0.43 mM for ADP. With these results, it was experimentally revealed that the ybcF gene of E. coli encodes catabolic CK, which completes anaerobic allantoin degradation through substrate-level phosphorylation. Therefore, we suggest renaming the ybcF gene as allK.

• Fisheries and Aquatic Sciences
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• v.26 no.8
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• pp.470-481
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• 2023

Algal overgrowth in shrimp culture ponds can affect the quality of the aquatic environment, thereby adversely affecting the shrimp and causing economic losses. The objective of this study was to evaluate the variation in phytoplankton composition in intensive shrimp ponds in Bac Lieu province, Vietnam. Phytoplankton samples were collected in three black tiger shrimp (Penaeus monodon) ponds and three whiteleg shrimp (Litopenaeus vannamei) ponds. The collected data were analyzed using SPSS and canonical correlation analysis softwares. In total, 75 species of phytoplankton were recorded in black tiger shrimp ponds and 64 species in whiteleg shrimp ponds. Diatoms had the highest species diversity with 29-30 species (39%-47%), followed by green algae with 9-19 species (14%-25%); species numbers of other phyla varied from 5-12 (8%-16%). The total number of phytoplankton species throughout the study varied from 34-50 species. Algal density was relatively high and ranged from 497,091-2,229,500 ind./L and 1,301,134-2,237,758 ind./L in black tiger shrimp and whiteleg shrimp ponds, respectively. The diatom density tended to increase during the final stage of the production cycle in black tiger shrimp ponds. Blue-green algae and dinoflagellates also increased in abundance at the end of the cycle, which can affect shrimp growth. Diatoms were significantly positively correlated with pH, salinity, total ammonia nitrogen, and nitrate (NO₃^-) concentrations (p < 0.05). Blue-green algae and dinoflagellates were positively correlated with salinity, phosphate (PO₄^3-), and NO₃^-. Algal species diversity was lower in the whiteleg shrimp ponds than in the black tiger shrimp ponds. Several dominant algal genera were recorded in the shrimp ponds, including Nannochloropsis, Gyrosigma, Chaetoceros, Alexandrium, and Microcystis. The results of this study provide basic data for further investigations, and they contribute to the management of algae in brackish-water shrimp ponds.

• Korean Journal of Agricultural Science
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• v.48 no.4
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• pp.965-973
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• 2021

The intention of this research is to analyze the effects of lactulose (LAC) supplementation on the growth performance, nutrient digestibility, microbial shedding, and fecal noxious gas emissions on weaning pigs in a 42-day trial. Based on the initial body weight and sex, a total of 255 piglets (21 day old) were randomly allocated into one of three dietary treatments with 15 replications and five pigs (two female and three male) per pen. The dietary treatments were as follows: a corn-soybean meal-based basal diet (CON) supplemented with 0, 1, and 2 g·kg^-1 of LAC. During phase 1, significant (p < 0.05) increases in the average daily feed intake and average daily gain (ADG) were observed, whereas during phase 2 and overall experimental period, significant improvements (p < 0.05) in the body weight, ADG, and gain to feed ratio were observed in pigs fed a graded level of LAC compared to those fed the CON diet. Additionally, dietary LAC supplementation significantly improved (p < 0.05) the nutrient digestibility dry matter, nitrogen, and gross energy in both phase 1 and phase 2. Moreover, the inclusion of LAC supplementation significantly increased (p < 0.05) the fecal Lactobacillus counts and reduced (p > 0.05) the E. coli counts in pigs. Furthermore, LAC supplementation reduced (p > 0.05) fecal ammonia and hydrogen sulfide gas emissions during phase 2. The results here indicate that the addition of lactulose at 1 g·kg^-1 and/or 2 g·kg^-1 would be optimal to improve the performance outcomes of weaning piglets.

• Animal Bioscience
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• v.36 no.12
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• pp.1842-1852
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• 2023

Objective: Hairy vetch is considered to improve the nutritional value of corn because of its high protein and mineral levels. To better understand the mechanism underlying hairy vetch regulated whole-plant corn silage fermentation, this experiment investigated the fermentation quality and bacterial community of whole-plant corn and hairy vetch mixture. Methods: Whole-plant corn and hairy vetch were mixed at ratios of 10:0 (Mix 10:0), 8:2 (Mix 8:2), 6:4 (Mix 6:4), 4:6 (Mix 4:6), 2:8 (Mix 2:8), and 0:10 (Mix 0:10) on a fresh weight basis. After ensiling 60 days, samples were collected to examine the fermentation dynamics, ensiling characteristics, and bacterial communities. Results: Mix 0:10, Mix 2:8, and Mix 4:6 showed poor fermentation characteristics. Mix 8:2 and Mix 6:4 silages showed high quality, based on the low pH, acetic acid, and ammonia nitrogen levels and the high lactic acid, crude protein, and crude fat contents. The bacterial diversity was affected by the mixing ratio of the two forage species. The genus Lactobacillus dominated the bacterial community in Mix 10:0 silage, whereas with the addition of hairy vetch, the relative abundance of unclassified-Enterobacter increased from 7.67% to 41.84%, and the abundance of Lactobacillus decreased from 50.66% to 13.76%. Conclusion: The silage quality of whole-plant corn can be improved with inclusion levels of hairy vetch from 20% to 40%.

• Animal Bioscience
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• v.37 no.4
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• pp.655-667
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• 2024

Objective: This study aimed to assess the impact of a hydroethanolic extract of walnut green husks (WGH) on rumen fermentation and the diversity of bacteria, methanogenic archaea, and fungi in sheep fed a high-concentrate diet. Methods: Five healthy small-tailed Han ewes with permanent rumen fistula were selected and housed in individual pens. This study adopted a self-controlled and crossover design with a control period and an experimental period. During the control period, the animals were fed a basal diet (with a ratio of concentrate to roughage of 65:35), while during the treatment period, the animals were fed the basal diet supplemented with 0.5% hydroethanolic extract of WGH. Fermentation parameters, digestive enzyme activities, and microbial diversity in rumen fluid were analyzed. Results: Supplementation of hydroethanolic extract of WGH had no significant effect on feed intake, concentrations of total volatile fatty acids, isovalerate, ammonia nitrogen, and microbial protein (p>0.05). However, the ruminal pH, concentrations of acetate, butyrate and isobutyrate, the ratio of acetate to propionate, protozoa count, and the activities of filter paper cellulase and cellobiase were significantly increased (p<0.05), while concentrations of propionate and valerate were significantly decreased (p<0.05). Moreover, 16S rRNA gene sequencing revealed that the relative abundance of rumen bacteria Christensenellaceae R7 group, Saccharofermentans, and Ruminococcaceae NK4A214 group were significantly increased, while Ruminococcus gauvreauii group, Prevotella 7 were significantly decreased (p<0.05). The relative abundance of the fungus Pseudomonas significantly increased, while Basidiomycota, Fusarium, and Alternaria significantly decreased (p<0.05). However, there was no significant change in the community structure of methanogenic archaea. Conclusion: Supplementation of hydroethanolic extract of WGH to a high-concentrate diet improved the ruminal fermentation, altered the structure of ruminal bacterial and fungal communities, and exhibited beneficial effects in alleviating subacute rumen acidosis of sheep.

• Journal of the Korean Society of Industry Convergence
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• v.27 no.2_2
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• pp.475-485
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• 2024

In many regions of Korea, including the Four Major Rivers, the seriousness of the problem of algal blooms due to eutrophication of water quality is being raised.In this study, in order to solve these social problems, we manufactured a filter using natural mineral fusion (red illite, zeolite, germanium ceramic, selenium ceramic, carbon ceramic) and independently developed a tank system for green algae experiments to observe and determine the stages of change in water quality. In order to study ways to improve water quality through quantitative analysis, 1 ton of severely polluted green algae water from the Nak dong River region was stored in a water tank and exposed to ultraviolet rays in the same environment as the Nak dong River. Then, the same environment as the Nak dong River was created. The results were derived from a 5-week water quality test. The results of this experiment confirmed that green-colored cyano bacteria were significantly reduced just by the turbidity results. The results were obtained through a request to the Korea Testing & Research Institute located in Changwon-si, Gyeong sang nam-do. CI-(chlorine ion) and NH3-N(ammonia nitrogen) had the effect of saving every week. The device used in this study was made of natural minerals free of heavy metals that are harmless to the human body and nature through long-term consideration and exploration to kill and prevent various strains living in water. Green purification system using natural hydrogen generating mineral filter were effective a non-chemical and physical methods. The results of this study are one way to contribute to the serious problems caused by green algae in many countries, and will contribute to the water quality environment by preventing the waste of environmental resources, improving the health of the people, and increasing the ability to purify environmental water quality at home and abroad.

• Journal of the Korean Electrochemical Society
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• v.27 no.1
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• pp.8-14
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• 2024

Austenitic stainless steel 316L has been used a lot of applications because of its high corrosion resistance and formability. In addition, copper brazing is employed to create complex shape of 316L stainless steel for various engineering parts. In such system, copper-based filler metals make galvanic cell at metal/filler metal interface, and it accelerates corrosion of stainless steel. Furthermore, Cu-rich region formed by diffused copper in austenitic stainless steel can promote a pitting corrosion. In this study, we used an ammonia (NH₃) gas to nitride the 316L stainless steel for improving the corrosion resistance. The thickness of the nitride (nitrogen high) layer increased with the treatment temperature, and the surface hardness also increased. The potentiodynamic polarization test showed the improvement of corrosion resistance of 316L stainless steel by enhancing the passivation on nitride layer. However, in case of high temperature nitriding, a chromium nitride was formed and its fraction increased, so that the corrosion resistance was decreased compared to the intact 316L stainless steel.

• The Korea Journal of Herbology
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• v.39 no.3
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• pp.97-105
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• 2024

Objective : This study examined the effects of yaksun recipe on the anti-fatigue and endurance enhancement properties in the forced swimming test (FST). Methods : The treatment groups were divided randomly into three groups: water-treated FST (control), 200 mg/kg of red ginseng-treated FST (RG200), 200 mg/kg of water extract of yaksun recipe-treated FST (YS200). After FST, an autopsy was performed, and the tissue and serum were collected. Results : The swimming exhaustion time in the RG200 and YG200 groups were significantly increased compared to the control group. The YG200 group fatigue indicators, D-Lactate, LDH(lactate dehydrogenase), creatine kinase, and ammonia content, significantly decreased compared to the control group. In addition, liver glycogen content significantly increased in the YG200 and tended to increase in RG200. Likewise, the glucose contents were significantly increased compared to the control group. The muscle damage indicators GPT (glutamic pyruvic transaminase) and BUN (blood urea nitrogen), a protein metabolite, in the YG200 group significantly decreased compared to the control group. Furthermore the concentration of liver lipid peroxidation, MDA(malondialdehyde) levels significantly decreased in the RG200 and YG200 compared to control group. Conclusions : These results suggest that YG200 can increase the endurance exercise capacity by decreasing the fatigue indicators, saving glycogen, and elevating the antioxidant defense system.

• The Journal of the Korea institute of electronic communication sciences
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• v.19 no.3
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• pp.531-538
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• 2024

While the importance of the water quality environment is being emphasized, the water quality index for improving the water quality of urban rivers in Gwangju Metropolitan City is an important factor affecting the aquatic ecosystem and requires accurate prediction. In this paper, the XGBoost and LightGBM machine learning algorithms were used to compare the performance of the water quality inspection items of the downstream Pyeongchon Bridge and upstream BanghakBr_Gwangjucheon1 water systems, which are important points of Gwangju Stream, as a result of statistical verification, three water quality indicators, Nitrogen(TN), Nitrate(NO3), and Ammonia amount(NH3) were predicted, and the performance of the predictive model was evaluated by using RMSE, a regression model evaluation index. As a result of comparing the performance after cross-validation by implementing individual models for each water system, the XGBoost model showed excellent predictive ability.