• Journal of Mushroom
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• v.18 no.4
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• pp.398-402
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• 2020

This study was conducted to set up a proper replacement cycle of High Efficiency Particulate Air (HEPA) filters by observing the microbial populations in the air of the cultivation house of Pleurotus eryngii, before and after HEPA filter replacement at different periods. The density of bacteria and fungi in the air during each cultivation stage was measured using a sampler before the replacement of the HEPA filter. The results showed that airborne microorganisms had the highest density in the mushroom medium preparation room, with 169.7 CFU/㎥ of bacteria and 570 CFU/㎥ of fungi, and the removed old spaun had 126.3 CFU/㎥ of bacteria and 560 CFU/㎥ of fungi. The density of bacteria and fungi in the air at each cultivation stage before the replacement of the HEPA filter was 169.7 CFU/㎥ and 570 CFU/㎥, and 126.3 CFU/㎥ and 560 CFU/㎥, during the medium production and harvesting processes, respectively. After the replacement of the HEPA filter, the bacterial density was the lowest in the incubation room and the fungal density was the lowest in the cooling room. The microbial populations isolated at each period consisted of seven genera and seven species before the replacement, including Cladosporium sp., six genera and six species after 1 month of replacement, including Penicillium sp., 5 genera and 7 species after 3 months of replacement, including Mucor plumbeus, and 5 genera and 12 species, 5 genera and 10 species, and 5 genera and 10 species, 4, 5, and 6 months after the replacement, respectively, including Penicillium brevicompactum. During the period after replacement, the species were diversified and their number increased. The density of airborne microorganisms decreased drastically after the replacement of the HEPA filter. Its lowest value was recorded after 2 months of replacement, and it increased gradually afterwards, reaching a level similar to or higher than that of the pre-replacement period. Therefore, it was concluded that replacing the HEPA filter every 6 months is effective for reducing contamination.

• Korean Journal of Poultry Science
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• v.48 no.4
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• pp.267-275
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• 2021

The aim of this study was to analyze the effect of dietary supplementation with ginseng berry, stems, and leaves on the growth performance, organ development, and blood biochemical characteristics of broilers. One hundred twenty one-day-old male broiler chicks (Ross 308) were randomly allocated to five groups: control (CON), ginseng berry 0.5% (GB1), ginseng berry 1.0% (GB2), ginseng stems and leaves 0.5% (GLS1), and ginseng stems and leaves 1.0% (GLS2). During the grower period (1-21 d), the body weight gain of all ginseng by-product fed groups was significantly higher (p<0.05) than that of the control group. During the finisher period (22-35 d), the feed intake in GLS2 was significantly higher (p<0.05) than that in the other groups, but there was no significant difference in weight gain or feed conversion ratio. No significant differences were detected among treatments when the growth performance was analyzed throughout the entire period (1-35 d). There was no significant difference in the serum biochemical profile, except for blood glucose. Glucose levels were significantly lower (p<0.05) in GLS groups, and tended to be lower in GB groups when compared to the control. Major organ weights showed no significant differences among treatment groups when compared to each other. In conclusion, dietary supplementation of ginseng by-products may improve the early growth of broiler chickens and reduce blood glucose levels.

• Composites Research
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• v.36 no.1
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• pp.1-15
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• 2023

Demand for energy consumption reduction is increasing according to the development expectations of future mobility. Lightweight structural materials are known as a method to reduce greenhouse gas emissions and improve energy efficiency. In particular, fiber reinforced polymer composite (FRP) is attracting attention as a material that can replace existing metal alloys due to its excellent mechanical properties and light weight. In this paper, industrial applications and research trends of carbon fiber reinforced composites (CFRP, carbon FRP) and self-reinforced composites (SRC) were reviewed based on the reinforcement, polymer matrix, and manufacturing process. In order to overcome the expensive process cost and long manufacturing time of the epoxy resin-based autoclave method, which is mainly used in the aircraft field, mass production of CFRP-applied electric vehicles has been reported using a high-pressure resin transfer molding process including fast-curing epoxy. In addition, thermoplastic resin-based CFRP and interface enhancement methods to solve the recycling issue of carbon fiber composites were reviewed in terms of materials and processes. To form a perfect matrix-reinforcement interface, which is known as the major factor inducing the excellent mechanical properties of FRP, studies on SRC impregnated with the same matrix in polymer fibers have been reported. The physical and mechanical properties of SRC based on various thermoplastic polymers were reviewed in terms of polymer orientation and composite structure. In addition, a copolymer matrix strategy for extending the processing window of highly drawn polypropylene fiber-based SRC was discussed. The application of CFRP and SRC as lightweight structural materials can provide potential options for improving the energy efficiency of future mobility.

• Journal of The Korean Association For Science Education
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• v.29 no.2
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• pp.179-192
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• 2009

The purpose of this study was to examine the effects of Small-Scale Chemistry (below SSC) Lab Program with respect to students' extroversions and introversions. For this study, an SSC Lab Program was developed on the basis of analyzing the chemistry part of the high school science textbook in the 7th curriculum. The experimental group received SSC experiment lessons, and the comparison group received traditional experiment lessons based on textbook for 5 class periods. Afterwards, students were grouped into extrovert and introvert according to their personality test scores, the differences between the two groups were investigated using 2-way ANCOVA. Prior to the instructions, three test regarding the scientific attitude and academic self-efficacy were administered. After the instructions, the scientific attitude, academic self-efficacy, and students' perceptions on SSC Lab Program were examined. The scores in mid-term and end-of-term science exams were used as pre-test and post-test science achievement scores, respectively. Two-way ANCOVA results revealed that there were effects in the score of the academic achievement score, but there was no interactive effect between extroversion/introversion and treatment. In addition, a significant interactive effect was found in the scientific attitude, but there was no significant main effect. It was interpreted that extrovert students had many opportunities in SSC experiment classes and were able to experiment with initiative, but introverts would feel the responsibility and the pressure owing to the small group experiment. There were no main and interactive effects in the score of the academic self-efficacy test. Survey of students' perceptions on SSC Lab Program revealed that both over 90% extrovert and introvert students showed very positive perceptions in 'three-membered small group composition,' 'understanding,' and 'convenience' items. It was found to be a very different perception between extrovert and introvert students in 'comparing result with other students' item.

• Journal of Mushroom
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• v.22 no.2
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• pp.60-66
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• 2024

This study was conducted to selection and investigate appropriate conditions for mass production of antagonistic microbes to control cobweb disease caused by Cladobotryum mycophilum. A grampositive bacterium was isolated from spent substrate of Agaricus bisporus and showed significant antagonistic activity against Cladobotryum mycophilum. The bacterium was identified as Bacillus altitudinis. based on the cultural, biochemical and physiological characteristics, and 16S rRNA sequence. The isolate is saprophytic, but not parasitic nor pathogenic to cultivated mushroom whereas it showed strong inhibitory effects against C. mycophilum cells in vitro. The control efficacy of B. altitudinis HC7 against cobweb disease of C. mycophilum was up to 78.2% on Agaricus bisporus. The suppressive bacterium may be useful for the development of biocontrol system. To define the appropriate conditions for the mass production of the Bacillus altitudinis HC7, we have investigated appropriate culture conditions and effects of various nutrient source on the bacterial growth. The appropriate initial pH and temperature were determined as pH 6.0 and 30℃, respectively. The appropriate concentration of medium elements for the growth of pathogen inhibitor bacterium(Bacillus altitudinis HC7) was determined as follows: 3.0% soluble startch, 10% soytone, 1.0% (NH₄)₂HPO₄, 1.0 mmol KCl, and 0.5% L-asparagine.

• Journal of Food Hygiene and Safety
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• v.27 no.3
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• pp.233-246
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• 2012

In this study, we investigated the applicability of the photostimulated luminescence(PSL), thermoluminescence(TL) and electron spin resonance(ESR) methods for various foods which are not allowed to be irradiated in Korea. All 15 foods including sesame, almond, peanut, cocoa powder etc. were analyzed. Samples were irradiated at 1~10 kGy using a $^{60}Co$ gamma-ray irradiator. In PSL study, the photon counts of all the unirradiated samples showed negative(lower than 700). The photon counts irradiated(1 kGy) dried shrimp, roasted peanut and seasoned peanut showed positive(higher than 5,000) and the other samples were negative or intermediate(> 700 and < 5,000). In TL analysis, results showed that it is possible to apply TL method to all foods containing minerals. In ESR measurements, the ESR signal(single-line) intensity of irradiated foods was higher than non-irradiated foods. In particular, the specific ESR signals of irradiation-induced crystalline sugar, cellulose and bone radical were detected in dried plum, raisin, dried cherry, mango(dried, frozen), rambutan, cocoa(powder), cinnamon, parsley, carrot, broccoli, dried arrow squid, dried pollack and dried shrimp. According to the results, PSL, TL and ESR methods were successfully applied to detect the irradiated foods because TL method is not able to detect the irradiated foods rarely composed of minerals. ESR is also a difficult method to detect the changes of ESR signal patterns of food. It is concluded that TL analysis or ESR assay is suitable for detection of irradiated samples and a combined method is recommendable for enhancing the reliability of detection results.

• Journal of the Korean Society of Food Science and Nutrition
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• v.34 no.7
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• pp.987-999
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• 2005

The purpose of this study was to evaluate the effect of short-term nutrition education camp on food and nutrient intakes of obese children. The subjects of the study were 30 obese children in Gumi city who have obesity index over $130\%$. The food consumption of the subjects was surveyed for three days before the camp, for eleven days during the first camp and for three days after the second camp, by food record method. The mean intakes of energy and carbohydrates in obese children were significantly decreased during and after the nutrition education camp, and that of vitamin C was significantly increased after the camp. The mean daily total food intake of the subjects was gradually decreased from 1646.4g before the camp to 1438.6g during the camp and 1412.66g after the camp. Energy and fat intake ratios from grains and milks were significantly decreased after the camp compared with that before the camp, and the energy intake ratio from grains, milks and eggs was significantly low during the camp. The protein intake ratios from grains, potatoes, vegetables and fishes were significantly increased after the camp. The calcium intake ratios from potatoes and milks were significantly increased during and after the camp, and the ratio from eggs was significantly decreased after the camp. The iron intake ratios from potatoes and fishes were significantly increased during and after the camp, and the ratio from grains was significantly low during the camp. The results of the study demonstrated that the short-term nutrition education program positively affected the overall food consumption and nutrients intakes of obese children.