• Journal of Microbiology and Biotechnology
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• v.32 no.1
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• pp.27-36
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• 2022

Ever since bioplastics were globally introduced to a wide range of industries, the disposal of used products made with bioplastics has become an issue inseparable from their application. Unlike petroleum-based plastics, bioplastics can be completely decomposed into water and carbon dioxide by microorganisms in a relatively short time, which is an advantage. However, there is little information on the specific degraders and accelerating factors for biodegradation. To elucidate a new strain for biodegrading poly-3-hydroxybutyrate (PHB), we screened out one PHB-degrading bacterium, Microbulbifer sp. SOL03, which is the first reported strain from the Microbulbifer genus to show PHB degradation activity, although Microbulbifer species are known to be complex carbohydrate degraders found in high-salt environments. In this study, we evaluated its biodegradability using solid- and liquid-based methods in addition to examining the changes in physical properties throughout the biodegradation process. Furthermore, we established the optimal conditions for biodegradation with respect to temperature, salt concentration, and additional carbon and nitrogen sources; accordingly, a temperature of 37℃ with the addition of 3% NaCl without additional carbon sources, was determined to be optimal. In summary, we found that Microbulbifer sp. SOL03 showed a PHB degradation yield of almost 97% after 10 days. To the best of our knowledge, this is the first study to investigate the potent bioplastic degradation activity of Microbulbifer sp., and we believe that it can contribute to the development of bioplastics from application to disposal.

• Journal of Microbiology and Biotechnology
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• v.32 no.5
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• pp.582-593
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• 2022

Among abiotic stresses in plants, drought and chilling stresses reduce the supply of moisture to plant tissues, inhibit photosynthesis, and severely reduce plant growth and yield. Thus, the application of water stress-tolerant agents can be a useful strategy to maintain plant growth under abiotic stresses. This study assessed the effect of exogenous bio-based 2,3-butanediol (BDO) application on drought and chilling response in tomato and turfgrass, and expression levels of several plant signaling pathway-related gene transcripts. Bio-based 2,3-BDOs were formulated to levo-2,3-BDO 0.9% soluble concentrate (levo 0.9% SL) and meso-2,3-BDO 9% SL (meso 9% SL). Under drought and chilling stress conditions, the application of levo 0.9% SL in creeping bentgrass and meso 9% SL in tomato plants significantly reduced the deleterious effects of abiotic stresses. Interestingly, pretreatment with levo-2,3-BDO in creeping bentgrass and meso-2,3-BDO in tomato plants enhanced JA and SA signaling pathway-related gene transcript expression levels in different ways. In addition, all tomato plants treated with acibenzolar-S-methyl (as a positive control) withered completely under chilling stress, whereas 2,3-BDO-treated tomato plants exhibited excellent cold tolerance. According to our findings, bio-based 2,3-BDO isomers as sustainable water stress-tolerant agents, levo- and meso-2,3-BDOs, could enhance tolerance to drought and/or chilling stresses in various plants through somewhat different molecular activities without any side effects.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.7
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• pp.33-40
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• 2021

Current industrial flow is directed toward reducing the usage of raw materials by reusing parts, which is referred to as a circular economy (CE). Repair is one of the most value-added approaches in CE, which can be efficiently accomplished via additive manufacturing. The repair technology of metallic parts via the directed energy deposition process, which includes the selective removal and redeposition of damaged regions of metallic parts. Residual stress characteristics depend on the shape of the part and the shape of the redeposition region. The objective of this study is to investigate the effects of the radius and corner position of the substrate on the residual stresses for repair by using finite element analysis (FEA). The residual stress distribution of the 45° angle groove at the edge of the circular shape models on the outer and inner radii was analytically investigated. The analysis was accomplished using SYSWELD software by applying a moving heat source with defined material properties and cooling conditions integrated into the FEA model. The results showed a similar pattern of concentrated stress distribution for all models except the 40-mm and 60-mm radii, for which the maximum stress locations were different. The maximum residual stresses are high but lower than the yield strength, suggesting the absence of cracks and fractures due to residual stresses.

• The Korea Journal of Herbology
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• v.28 no.1
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• pp.15-21
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• 2013

Objectives : To evaluate the safety of KOB, a polyherbal medicine for allergic rhinitis, we conducted a subchronic toxicology study. Methods : Dried extract of KOB(Lot. No. 11003, yield : 41.1%) was prepared from GLP company (Hanpoong Pharm & Food Co., Ltd). KOB was repeatedly administrated orally of male SD rats at daily dose levels of 500 (G2), 1250 (G3) and 5000 (G4) mg/kg/day for 13 weeks. We recorded the clinical signs of toxicity, body weight, food intake/consumption, optometry, urine analysis, organ weights, hematology, and conducted serum biochemical analysis, necropsy, gross and histological changes in target organs of Sprague-Dawley rats, and clinical chemistry analysis. Results : Neither death nor any toxicological signs were obserbed in KOB at all doses of 500, 1250 and 5000 mg/kg/day during the administration period for thirteen-week. Furthermore, there was no difference in body weight and food-take consumption, optometry, necropsy, organ weight, gross pathological findings, and urine analysis among the groups of rats treated with different doses of KOB, during at the observation period for thirteen-week. The hematological analysis and clinical blood chemistry data were revealed no toxic effects from repeated-dose administration of KOB in rats during the observation period. Conclusions : Based on these results, the no observable adverse effect level (NOAEL) of KOB was considered to be 5000 mg/kg/day for male rats under these study conditions.

• ALGAE
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• v.37 no.2
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• pp.105-121
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• 2022

Modern seaweed farming relies heavily on seedlings from natural beds or vegetative cuttings from previous harvests. However, this farming method has some disadvantages, such as physiological variation in the seed stock and decreased genetic variability, which reduces the growth rate, carrageenan yield, and gel strength of the seaweeds. A new method of seedling production that is sustainable, scalable, and produces a large number of high-quality plantlets is needed to support the seaweed farming industry. Recent use of tissue culture and micropropagation techniques in eucheumatoid seaweed production has yielded promising results in increasing seed supply and growing uniform seedlings in large numbers in a shorter time. Several seaweed species have been successfully cultured and regenerated into new plantlets in laboratories using direct regeneration, callus culture, and protoplast culture. The use of biostimulants and plant growth regulators in culture media increases the seedling quality even further. Seedlings produced by micropropagation grew faster and had better biochemical properties than conventionally cultivated seedlings. Before being transferred to a land-based grow-out system or ocean nets for farming, tissue-cultured seedlings were recommended to undergo an acclimatization process to increase their survival rate. Regular monitoring is needed to prevent disease and pest infestations and grazing by herbivorous fish and turtles during the farming process. The current review discusses recent techniques for producing eucheumatoid and other valuable seaweed farming materials, emphasizing the efficiency of micropropagation and the transition from laboratory culture to cultivation in land-based or open-sea grow-out systems to elucidate optimal conditions for sustainable seaweed production.

• Korean Journal of Materials Research
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• v.32 no.10
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• pp.419-424
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• 2022

Halide perovskite solar cells (PSCs) have improved rapidly over the past few years, and research on the optoelectrical properties of halide perovskite thin films has grown as well. Among the characterization techniques, photoluminescence (PL), a method of collecting emitted photons to evaluate the properties of materials, is widely applied to evaluate improvements in the performance of PSCs. However, since only photons emitted from the film in the escape cone are included, the photons collected in PL are a small fraction of the total photons emitted from the film. Unlike PSCs power conversion efficiency, PL measuring methods have not been standardized, and have been evaluated in a variety of ways. Thus, an in-depth study is needed of the methods used to evaluate materials using PL spectra. In this study, we examined the PL spectra of the perovskite light harvesting layer with different measurement protocols and analyzed the features. As the incident angle changed, different spectra were observed, indicating that the PL emission spectrum can depend on the measuring method, not the material. We found the intensity and energy of the PL spectra changes were due to the path of the emitted photons. Also, we found that the PL of halide perovskite thin films generally contains limited information. To solve this problem, the emitted photons should be collected using an integrating sphere. The results of this study suggest that the emission spectrum of halide perovskite films should be carefully interpreted in accordance with PL measuring method, since PL data is mostly affected by the method.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.29 no.2
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• pp.118-127
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• 1984

In order to find an appropriate model for rice crop-season, the possibility to utilize the geographical conditions instead of meteorological factors was examined on the data from the Local Adaptability Test(LAT) conducted over the country from 1962 to 1980. The mutiple regression model, $Y={\Upsilon}={\ss}{\sum}_{i=1}^n{\beta}^1X^iwas applied on seeding, transplanting, heading and marginal heading date, and multiple regression coefficients(\beta) and multiple correlation coefficients (R) were tested. Two varietal groups, japonica(1962-l971) and indica/japonica(l972-1980) were separately tested. The application of these established models, growth duration in nursery and paddy field, cultural season, and the relation between heading date and yield are reviewed.

• Journal of the Korean Society of Industry Convergence
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• v.26 no.1
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• pp.87-94
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• 2023

TMCP(Thermo Mechanical Control Process) steel was continuously cast (CC) by varying the argon gas flow rate and vacuum time in the Ruhrstahl Heraeus (RH) refining process. Using the CC specimens, the distribution of the inclusions and the mechanical properties were evaluated. A lot of oxides and Al-O type inclusions were observed. The average Vickers hardness did not show a constant, but showed dispersion in a certain range. The shape and scale parameters of the CC specimen with an argon gas flow rate of 160Nm³ and a vacuum time of 12 minutes was the best. Mechanical properties (tensile strength, yield strength and elongation) were consistent with the Weibull probability distribution analysis results. The impact resistance was the best for CC specimens with an argon flow rate of 140 Nm³ and a vacuum time of 12 minutes. Although the inclusions and mechanical properties of the CC specimens were evaluated according to the argon gas flow rate and vacuum time, these values were no significant difference.

• Microbiology and Biotechnology Letters
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• v.51 no.1
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• pp.43-52
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• 2023

The purpose of this study is to confirm the antioxidant, black hair, and hair growth effects of the N. jatamansi, O. basilicum, and C. sativus mixed extracts that pharmacological efficacy has been verified. Accordingly, four samples (NOC-1 to-4) produced under different extraction conditions were prepared and the results are as follows. First, all samples showed an increase in antioxidant content in a concentration-dependent manner from the results of antioxidant efficacy. In particular, NOC-4 extracted by steaming and ultrasonic methods showed the highest antioxidant effect among the four samples. As a result of analysis of the amount of melanin production in mouse melanoma cells, NOC-4 with concentration of 500 ㎍/ml showed higher melanin production compared to the control group, so the black hair efficacy was the best. Also, in the hair growth test results, it was found that the hair growth was the best at 0.94 ± 0.10 mm at experimental group orally administered with 500 mg/kg of NOC-4. In addition, as a result of cytotoxicity analysis in mouse melanoma cells, the safety of samples was demonstrated by maintaining cell viability of 95% or more at all concentrations. These results suggest that the steaming and ultrasonic extraction method increased the extraction yield of active ingredients for antioxidant, melanin, and hair generation, thereby affecting physiological activity. Based on these results, if the steaming and ultrasonic extraction methods are applied to the mixed extraction of N. jatamansi, O. basilicum, and C. sativus, it is judged that the practical potential as a natural material for black hair and hair growth agents will increase.

• Food Science of Animal Resources
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• v.43 no.3
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• pp.502-511
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• 2023

The use of nitrite as a conventional curing agent is decreasing because of the negative consumer perception of synthetic compounds in foods. Therefore, this study was conducted to investigate the efficacy of dongchimi as an alternative to synthetic nitrite and its effect on the qualitative properties of emulsion-type sausages. Under all tested fermentation conditions, both nitrite and nitrate contents were the highest when dongchimi was fermented at 0℃ for 1 wk. The fermented dongchimi was powdered and added to the sausages. Emulsion-type sausages were prepared with 0.25% (treatment 1), 0.35% (treatment 2), 0.45% (treatment 3), or 0.55% (treatment 4) dongchimi powder, with 0.01% sodium nitrite-treated (control 1) and 0.40% celery powder-treated (control 2) sausages as controls. There were not different (p>0.05) in the pH, cooking yield, CIE L^*, and CIE a^* between the control 1 and treatments 2, 3, and 4. CIE b^* was significantly higher (p<0.05) in the control 2 and lower (p<0.05) in the control 1 than that in the other groups. Treatment 4 and control 1 had similar contents of residual nitrite, nitrosyl hemochrome, and total pigment. Additionally, treatment 4 exhibited a significantly better (p<0.05) curing efficiency than the control 1. However, naturally cured sausages showed higher (p<0.05) lipid oxidation than the control 1. This study suggests that the use of more than 0.35% dongchimi powder could replace sodium nitrite or celery powder as curing agents for emulsion-type sausages.