• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.13 no.2
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• pp.112-120
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• 2008

A series of experiments were conducted to establish a marine ecotoxicological standard method using marine primary producers, Skeletonema costatum, Heterosigma akashiwo, Prorocentrum micans, Isochrysis galbana, Tetraselmis suecica as candidate test species. Marine diatom, S. costatum was selected as standard test species in terms of the ecological roles and international uses as test species. Test methods and test acceptability criteria are as follows; $72{\sim}96$ hr population growth inhibition $EC_{50}$ as endpoint. Static non-renewal method, and population growth rates over 0.04/hr in control as test acceptability criterium. S. costatum is widely distributed in the world ocean and used for standard species of marine toxicity test method by ISO (International Standardization Organization). Possible salinity ranges for this test method are $20{\sim}35\;psu$, and reproducibility and interlaboratory test results were consistent through the calibration tests. Sensitivity of the test method was comparable or better than other toxicity tests such as rotifer neonate mortality, bioluminescent bacterial inhibition, seaweed sporulation and sea urchin fertilization tests.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.13 no.2
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• pp.129-139
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• 2008

Marine ecotoxicological standard method was applicated using marine rotifer and benthic copepod as primary consumer of marine ecosystem. Marine rotifer, Brachionus plicatilis and benthic copepod, Tigriopus japonicus were designated as standard test species with the endpoints of 24hr neonate mortality (24hr $LC_{50}$) and 48hr population growth (48hr $EC_{50}$) for rotifer, and 48hr nauplius mortality (48hr $LC_{50}$) for benthic copepod. Tests method was referred to those of ASTM (American Society for Testing and Materials) with the replacement of test species which are widely distributed in Korean waters. The two species showed a wide tolerance on salinity ($5{\sim}35\;psu$) and can be easily cultured in small space even they were not as sensitive as in the mortality test using the nauplius of marine invertebrates. However, these species revealed the significant "concentrationresponse relationship" tested with ocean disposal wastes, and reproducibility using cadmium as standard reference material between laboratories. Accordingly, these two species have good potential as test species for marine ecotoxicological test species. Also, we strongly recommend that at least one of these species be included in the test species of "battery test" in marine bioassay.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.13 no.2
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• pp.147-155
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• 2008

A series of experiments were conducted to find standard test organisms and to develop test protocols for sediment toxicity tests using indigenous amphipods inhabited in Korean coastal environments. The indigenous amphipods Mandibulophoxus mai and Monocorophium acherusicum were well associated with various sediment substrates from sand to mud. The tolerance limits to various physico-chemical factors affecting bioassay results such as temperature, salinity and total ammonium as well as the sensitivities to contaminants in water and sediments were investigated using M. mai and M. acherusicum in the present study. These amphipods were tolerable to the adequate ranges of salinity ($10{\sim}30\;psu$), temperature ($10{\sim}25^{\circ}C$) and ammonia (<50 ppm). They have relevant sensitivities to the reference toxicants, dissolved cadmium as well as other metals and organic pollutants, when compared to the standard test species used in other countries. Field-sediment toxicity tests revealed that M. mai would be more sensitive to sediment-associated pollutants than M. acherusicum, while the sensitivity of M. acherusicum was comparable to those of other sediment test species in other countries. Overall results of this first attempt to develop an amphipod sediment toxicity test protocol in Korea indicated that M. mai and M. acherusicum should be applicable in the toxicity assessment of contaminated sediments, following the further evaluation encompassing various ecological and toxicological evaluation and the standardization of test method.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.13 no.2
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• pp.156-163
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• 2008

Luminescent bacterial toxicity test was first introduced in the early 1980s, registered as international standard method in 1998 and now widely used as a common toxicity test method. This toxicity test uses luminescent bacterium, Vibrio fischeri, originated from marine environment as a test organism. The degree of toxicity can be evaluated from the comparison of luminescent emission intensity between control and treatment groups to toxicants and materials from various environmental matrix for 30 min. This test can be carried out by using commercial products and its results are sensitive and precise. This research is on the feasibility of adopting luminescent bacterial test as a domestic standard test protocol. Using commercial products, a series of experiments were conducted to identify the precision and accuracy of injection volume and light emission, and to evaluate concentration-response relationship between chemical concentrations and light emissions. Also, the feasibility of the application to environmental media and quality assurance/quality control were checked. The results of serial toxicity tests revealed that the preliminary luminescent bacterial toxicity test was robust and suitable as a standard method.

• Journal of Industrial Convergence
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• v.22 no.5
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• pp.69-78
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• 2024

This study verified the relationship between marital conflict perceived by working mothers and the influence of children's cyber delinquency and the mediating effect of school life adaptation. For the analysis data, the 14th data of the Korean Children's Panel (2021) were used, and SPSS WIN 23.0 and PROCESS MACRO were used for analysis. The analysis method used the PROCESS MACRO Model Number 4 technique to verify the hypothesis, first, frequency analysis to understand the demographic and sociological characteristics of the survey subjects, second, technical statistics, correlation analysis to understand the technical statistics and correlations of major variables. As a result of the main analysis, first, it was found that marital conflict perceived by working mothers did not have a statistically significant effect on children's cyber delinquency. Second, in the relationship between marital conflict perceived by working mothers and cyber delinquency of children, school life adaptation had a complete mediating effect. Based on these results, it is significant in that it has presented basic data to prevent cyber delinquency problems before children who are active a lot online are exposed.

• Industry Promotion Research
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• v.9 no.1
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• pp.123-132
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• 2024

The purpose of this study was to improve the understanding of stress coping in the very old and elderly and to improve life satisfaction through stress reduction as the population ages. To this end, this study aimed to test the mediating effect of social support on the relationship between stress coping and life satisfaction among very old people. In particular, we paid attention to the differences in stress coping from the existing elderly population and took the view that they should be studied as an independent group. To confirm this, we analysed 275 men and women aged 85 years and older who responded to the fifth supplementary survey of the National Elderly Security Panel (KReIS) conducted by the National Pension Service. IBM SPSS 26 was used to test the mediating effect of social support on the effect of stress coping measures on life satisfaction in the very old elderly. The results of the significance test of the independent variables on the mediating variable showed that stress coping was positively significant, i.e., the higher the level of stress coping, the higher the life satisfaction. In addition, the results of the significance test of the effects of the independent variables and mediators on the dependent variable showed that coping with stress had a significant effect, and the mediator, social support, also had a significant effect on life satisfaction. Therefore, this study suggests the need for social support to improve the level of life satisfaction through coping with stress in the very old elderly.

• Information Systems Review
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• v.20 no.2
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• pp.87-110
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• 2018

This study reviews previous studies about the effects of RFID capabilities on strategic supply chain competence and business performance in the Chinese context. This study introduces a new perspective that measures the degree to which RFID capability levels contribute to business performance. Such an assumption is based on the fact that companies build their own capabilities through RFID capabilities and that these capabilities provide a competitive advantage for enterprises. Data on all sorts of logistics, distribution, and manufacturing companies that introduced RFID system in China were collected for data analysis. This study analyzes the structural equation modeling using Smart-PLS 2.0 program. This study confirms that internal reliability, convergent validity, and discriminant validity are satisfied. The hypothesis test result on the relationship between RFID capacity and strategic supply chain competence and strategic supply chain competence and company results is partially adopted. This study aids in establishing a RFID system construction strategy to enhance supply chain competence by suggesting guidelines for the successful introduction of RFID system through identifying the causal relationship between RFID capacity and strategic supply chain competence. This study also suggests the influence of RFID competency on visibility, agility, flexibility, and collaborations.

• The Journal of the Convergence on Culture Technology
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• v.10 no.2
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• pp.365-371
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• 2024

The purpose of this study was to investigate the effect of leisure satisfaction according to calligraphy activities of the elderly on self-efficacy and psychological well-being. In order to conduct this study, the researchers surveyed 306 elderly people aged 65-76 or older from late November to early December 2023 in Anyang City and Xinxiang City, Henan Province, China. In order to verify the research hypothesis, the researchers performed frequency analysis, descriptive statistics analysis, and Pearson correlation analysis using IBM SPSS Statistics 25, and then performed independent sample T-test and one-way analysis of variance (One-Way ANOVA). To verify the hypothesis through the measurement concept, related verification was conducted for Hayes PROCESS macro and Bootstrap. As a result of the study, first, there is a gender difference in leisure satisfaction, leisure satisfaction, self-efficacy, and psychological well-being, and leisure satisfaction and psychological well-being differ significantly according to age. Second, it was found that leisure satisfaction had a positive effect on self-efficacy. Third, it was found that leisure satisfaction had a positive effect on psychological well-being. Fourth, leisure satisfaction was found to have a positive effect on psychological well-being. Therefore, in order to increase the leisure satisfaction and psychological well-being of the elderly, it is necessary to carefully develop a calligraphy activity system to increase self-efficacy.

• Journal of the Korean Applied Science and Technology
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• v.40 no.6
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• pp.1278-1288
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• 2023

Hesperidin(HD) is a a potent antioxidant flavonoid found in various plants. In this study, the recovery of cell death, anti-inflammatory, and melanogenesis inhibitory activities of Hesperidin glucoside (HDG), a water-soluble HD, were compared with HD in vitro. HDG was prepared by an enzymatic glycosylation reaction from HD, and the water solubility of HDG was increased by more than 20,000 times compared to HD. Cell toxicity was significantly lower for HDG than HD. Both HD and HDG increase cell viability in UV damaged HaCaT cells. HD and HDG also reduced an inflammatory mediator such as nitric oxide (NO), and pro-inflammatory cytokines such as tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) in the cells irradiated with UV, and the reducing effect of HDG was slightly higher than that of HD. In the melanogenesis inhibition assay using the Melanoma B16F10 cells, HDG showed a superior inhibitory activity compared to HD. In conclusion, HDG, a glucosylated product of HD with high water solubility showed more than equal ability of cell recovery and anti-inflammatory potential, and higher melanogenesis inhibition activity compared to HD in vitro.

• Journal of the Korea Organic Resources Recycling Association
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• v.18 no.2
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• pp.45-54
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• 2010

Field study was conducted for 5 months to investigate the effect of leachate recirculation on aerobic landfill stabilization at active landfilling site. The area of field experiment was $24{\times}24m$ and 9 vertical air injection wells with screen ranging 3~9 m were installed. Aerobic landfill operation for 5 months increased average internal landfill temperature to $70^{\circ}C$ and 8 % of landfill height was settled down. $94m^3$ of leachate was recirculated for 1 month to increase moisture content of landfill to favor microbial degradation of organic matter, which resulted in temporary increase of groundwater level and anaerobic environment. But leachate recirculation triggered increase of internal landfill temperature of neighboring monitoring well. Because excessive leachate recirculation decreased internal landfill temperature by cooling effect, internal landfill temperature should be checked to avoid abrupt decrease of temperature during leachate recirculation. Also, to prevent anaerobic environment, intermittent leachate recirculation was recommended.