• Korean Journal of Environmental Agriculture
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• v.35 no.3
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• pp.223-233
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• 2016

BACKGROUND: This study was to develop a analytical reference material including twenty pesticides in tomato. To use it for proficiency test, the suitability of homogeneity, storage stability, assigned values and uncertainty for analytical reference material were important.METHODS AND RESULTS: In order to develop a analytical reference material of tomato for multi-residue analysis of pesticides, twenty-pesticides were treated in tomato and the samples were frozen and homogenized. The homogeneity, stability, assigned value and uncertainty were calculated according to the requirements of the KS A ISO Guide 35, KS Q ISO 13528 and EURL-PT protocol. The values of the within-bottle standard variation(s_wb) and the between-bottle standard variation(s_bb) were 0.9~6.5% of assigned value and the uncertainty(u*_bb) due to inhomogeneity was also calculated as 0.6~1.9% for all pesticides. This indicated that it was satisfactory to be used as a analytical reference material. The storage stabilities of twenty-pesticides at room temperature and freezing conditions were assessed according to the requirement of the KS Q ISO Guide 35. All pesticides were stable at room temperature (20~30℃) for 8 days and freezing (-20℃) for 23 days.CONCLUSION: The feasibility of analytical reference material for pesticide multi-residue analysis in a tomato matrix was investigated. Homogeneity of within/between-bottle, uncertainty and stabilities at room temperature and freezing condition were satisfactory for a use of proficiency test and quality control. From these results, a analytical reference material would be applicable to monitor the proficiency test of pesticide analysis organizations to improve the reliability and consistency.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.19 no.2
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• pp.136-140
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• 1986

The change of cell counts of Vibrio parahaemolyticus in fish muscle by the storage time and temperature was examined to get basic informations for precautionary steps against food poisoning of slices of raw fish (sashimi). There fore, we inoculated fish homogenate of oceanic bonito (Katsuwonus pelamis), yellow tail (Seriola quinqueradiata) with Kanagawa positive Vibrio parahaemolyticus and stored it at $30^{\circ}C,\;18^{\circ}C,\;4^{\circ}C\;and\;-20^{\circ}C$ for 24 hours. The number of the Vibrio parahaemolyticus upon fish homogenate stored at $30^{\circ}C\;and\;18^{\circ}C$ decreased for the first two hours and increased thereafter. When the fish homogenates inoculated with Vibrio parahaemolyticus at about $10^3$ per gram were stored at $18^{\circ}C\;and\;30^{\circ}C$ for 10 hours, the cell numbers increased about 10 times and 1,000 times initial cell numbers, respectively. The survival rate of Vibrio parahaemolyticus was about $20\%$, when the inoculated fish homogenates were stored at $-20^{\circ}C$ for 24 hours. Vibrio parahaemolyticus inoculated in fish homogenates was decreased by about $10\%$ of initial cell numbers by the storage at $4^{\circ}C$ for 4 hours and it was decreased by about $50\%$ after 24 hours storage of the samples at the same temperature. The decreasing rate of inoculated Vibrio parahaemolyticus in fresh fish muscle homogenate was higher than that in frozen fish muscle homogenate during the storage time at a refrigerator.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.2
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• pp.719-725
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• 2017

Frozen milk products are commonly made in small refrigeration machines. R-502 has long been used as a refrigerant for soft ice cream machines, but it is being replaced with R-404A due to the issue of ozone layer depletion. However, R-404A has high global warming potential, so it also needs to be replaced. In this study, a mixture of R-290 and R-32 was considered as a new refrigerant. An optimization and performance evaluation of the mixture were conducted for a freezer volume of 2.8 liters. The focus of the optimization was the appropriate refrigerant charge and the opening of the expansion valve. At the optimized conditions, ice cream was produced in 6 minutes and 24 seconds with the mixture, and the COP was 0.83. For R-404A, the ice cream production time was 6 minutes and 22 seconds, and the COP was 0.90. The results may be used for the design of food refrigeration machines and to optimize other refrigeration cycles.

• Clinical and Experimental Reproductive Medicine
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• v.30 no.3
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• pp.241-248
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• 2003

Objective: The purpose of this study was to evaluate the survival rate of vitrified blastocyst according to the freezing vessels, equilibration time in cryoprotectant and artificial dehydration method. Methods: Human blastocysts were vitrified after loading onto the plastic straw, open-pulled straw (OPS), electron microscopy grid (EM grid) for 1.5 min or 3 min. They also were directly plunged into LN2 within 30sec. For artificial shrinkage of blastocysts, 36 gauge fine needle was pushed at the cellular junction of the trophectoderm into the blstocoele cavity until it shrank without damage of inner cell mass. Results: The survival rate of vitrified blastocysts on plastic straw, OPS, EM grid as freezing vessels were 26.7, 13.0 and 60.5%, respectively. The survival rate of EM grid was significantly higher than that of plastic straw and OPS (p<0.05). For 1.5 min equilibrium, the survival rates of early blastocyst (EB), middle blastocyst (MB) and late blastocyst (LB) were 64.4, 81.0, and 20.0% respectively. For 3 min equilibrium, the survival rates of EB, MB, and LB were 69.9, 50.0 and 57.5% respectively. The survival rates of EB and MB were significantly higher than that of LB in 1.5 min equilibrium group (p<0.05), however, the significance was not observed in 3 min equilibrium groups. In cytoplasmic shrinkage before vitrification, the survival rates of EB, MB and LB were 92.9, 100 and 75.9% respectively. The survival rate of MB was significantly higher than that of LB (p<0.05). The survival rates of vitrified blastocysts by artificial dehydration and slow-frozen blastocysts were not significantly different as 88.9 and 66.7%, respectively. Conclusion: This study showed that the vitrification of human blastocysts using EM grid and artificial dehydration is an effective method. Therefore, these methods would be an useful techniques for blastocyst cryopreservation.

• Korean Journal of Veterinary Research
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• v.35 no.4
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• pp.793-807
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• 1995

This study was carried out to investigate the effects of diethyl maleate(DEM) on the carcinogenesis of forestomach and pyloric glandular stomach in rats caused by N-methyl-N'-nitro-N-nitrosoguanidine(MNNG). A total of 60 male 6-week-old Wistar rats were given twice intragastric injection of MMNG(200mg/kg BW), then were given diets containing 5% NaCl for 3 weeks until 4th week of the experiment. And then the animals of groups of 1 and 2 were placed on diets containing 0.2% DEM for 16 weeks until the end of 20 weeks of the experiment. On the other hand, the animals of groups of 3 and 4 were placed on basal diets for the same periods. The tissues of forestomach and liver of each group were frozen in liquid nitrogen and the activities of quinone reductase(QR) were determined by measurement of the dicoumarol-sensitive reduction of dichloro-indophenol by NADPH at 600nm. All rats were sacrificed at the end of 20 weeks of the experiment. Every animal was fasted for 24 hrs prior to sacrifice. The forestomach was fixed in 10% neutral phosphate buffered formalin for histology and the pyloric gland was fixed in sublimated formalin for immunohistochemistry of pepsinogen 1 altered pyloric gland(PAPG). The final body weight of the group given MNNG and treated with 5% NaCI and DEM was significantly decreased compared with that of the group 4(p<0.05). Food and water consumption rates were not significantly changed. The preneoplastic and neoplastic lesions of the forestomach given MNNG and treated with 5% NaCI and DEM were significantly increased compared to those of the group 4(p<0.0l). The incidence of PAPG in the groups treated with 0.2% DEM was significantly increased compared with that of the group 4(group 1:p<0.01, group 2:p<0.05). The activities of QR of forestomach in the groups treated with 0.2% DEM were significanitly increased compared with those of the group 4(p<0.001), but those of liver were not significant. These results indicate that DEM exert the enhancing effect of forestomach and glandular stomach carcinogenesis in rats pretreated with MNNG and NaCl.

• Journal of Wetlands Research
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• v.19 no.4
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• pp.409-422
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• 2017

In order to understand the environmental factors affecting the waterbird community in winter, we divided the watershed into 6 sections and investigated the size of the stream, the water quality, benthic invertebrates, and fish including birds. The influences on the community of water birds in Wonju stream were river structure, temperature and water quality. Among the structure of the river, the factors affecting the waterbird community in winter were the width of the stream and the width of the flowing water. The wider the width, the more species and the number of the winter waterbirds were. As the width of river water was wide, the smaller the width and width of the waterway, the fewer the population. The temperature changes of the wintering season affected the community of water birds because it led to freezing of rivers. The sections that were not frozen showed a significant increase and decrease in the temperature drop and rise. The values of pH, water temperature, COD, BOD, TN, TP and total E. coli increased with the increase of the downstream waterbirds population in the water quality survey. The water quality of S6 was affected by the downstream sewage treatment plant The number of wintering waterbirds was also highest. The effluent from the sewage treatment plant seems to have a considerable influence on the water quality. The increase of several items such as TN promotes the nutrition of the river, which leads to the accumulation of organic matter and the proliferation of aquatic organisms. This may be the cause of the increase in winter waterbirds as a food source. The benthic macroinvertebrate communities and fish communities did not show any correlation with the wintering water-birds communities.

• Journal of Life Science
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• v.22 no.1
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• pp.80-86
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• 2012

This study was conducted to improve quality of takju where natural honey is used to control the ripening fermentation and the amount of sediment derived from takju mash. A koji was prepared using rice starch and Aspergillus awamori var. kawachii. Takju mash was prepared by alcohol fermentation with Saccharomyces cerevisiae and a 3-step addition of steamed rice. The clean part of the mash (CPM) was separated from the sediment at $5^{\circ}C$ and 5% (w/v) of natural honey was added and then ripened for 23 days at 5, 10, or $15^{\circ}C$. Temperature, pH, acidity, and total sugar content showed no significant differences, but a 0.2 percent reduction in alcohol content occurred during storage. However, CPM ripened with honey had a comparatively higher score on sensory evaluation than did immature CPM with added honey added. Takju with 8% alcohol content was prepared by mixing the water from the mixed CPM ripened with honey together with 100, 50, and 25% of the frozen sediment. Several quality characteristics of the takju were checked over 37 days of fermentation at $10^{\circ}C$. The pH was sustained between 4.1 and 4.3, and changes in the number of viable yeast cells, acidity, total sugar amounts, and alcohol content showed similar patterns but differences in scale. Smaller amounts of sediment affected the stability of the takju. Mixing the CPM ripened with natural honey at low temperature moderately reduced the amount of sediment in the mash and resulted in a highly flavorful takju with an extended shelf life.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.22 no.5
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• pp.219-227
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• 1989

A new devised conductivity meter was used in the rapid and convinient determination of freshness of fish meats. Electric conductivity of frozen fishes like cod, tuna, flounder, Alaksa pollock were demonstrated about $6,100\pm200{\mu}u$ at the beginning of spoilage showed VBN content of $30\~35mg\%$ while that of fresh meat of yellow tail, rock trout, and mackerel were in the range of $5,100\~5,400{\mu}u$. The relationship between electric conductivity and freshness as measured by VBN content was direct proportion during the deterioration of fish meat. It was presumed that electric conductivity change of red muscled fish was more temperature dependence than that of white muscled fishes. $Q_{10}$ value of mackerel meat was about 2.34 at the temperature ranged from 15 to $30^{\circ}C(\pm1^{\circ}C)$). The electric conductivity obtained with conductivity meter could be a valuable criteria for the freshness test of fish meat determining in 10 seconds by handy compact portable meter.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.11 no.2
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• pp.85-90
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• 1978

In present study, the effect of various factors including the solvent concentration, extraction time, extraction temperature and the ratio of sample vs extraction solvent(w/v) upon the extractability of the NaOH soluble proteins of marine algae were investigated. Seven species of sun-dried algae, the major ones in consumption as food, namely Porphyra suborbiculata, Undaria pinnatifida(natural and cultivated), Sargassum fulvellum, Sargassum kjellmanianum, Ulva pertusa, Enteromorpha linza and Codium coarctatum were used for the extraction of the NaOH soluble protein. The frozen and masceratd samples were prepared by the same mettled described in previous paper(Lee, 1977). In case of the TCA insoluble protein, all samples reached maxima at 0.025M NaOH solution while the 0.05M for extractable total nitrogen. Variation of the ratio of sample vs solvent gave slight effect upon the extractability, 100 ml solvent added to 1 g dried sample was effective. The effect of extraction time on the extractability differed from species. The extractabilty of Enteromorpha linza, Ulva pertusa and Codium coarctatum reached maxima within 1 hour extraction and 2 hours for the cultivated Undaria pinnatifida while 3 flours for the natural Undaria pinnatifida, Sargassum fulvellum, Sargassum kjellmanianum and Porphyra suborbiculata. The most effective extraction temperature was $60^{\circ}C$ for all samples.

• Journal of the East Asian Society of Dietary Life
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• v.12 no.1
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• pp.7-14
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• 2002

This study investigated the effects of a 7 week nutritional educational program on the unbalanced dietary habits, tastes, dietary attitudes, and nutritional knowledge of 127 fourth grade students. The subjects were selected from seven elementary schools that were under the supervision of the Dongbu Office of Education in Incheon. Results showed that most of the subjects were fully aware of the fact that they were on an unbalanced diet. It was also revealed that the main reason for their unbalanced diet was that they tended not to eat foods that did not fit their tastes. After implementation of the 7 week nutritional education, the subjects'unbalanced dietary habits significantly decreased, but their desires to fix their unbalanced diet failed to increase. The subjects'tastes showed a positive change in their perception towards vegetables, seafood, and seaweed to a significant degree; however, their appetite far meat, eggs, beans, frozen floods, and processed goods did not show any noticeable change. A significant increase was also found on the level of the subjects'nutritional knowledge but not in their dietary habits and dietary attitudes.