• Korean Journal of Environmental Biology
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• v.37 no.1
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• pp.72-81
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• 2019

Bisphenol A (BPA), a representative endocrine disrupting chemicals, has adverse effects on growth, development and reproduction in aquatic organisms. The object of this study was to investigate the modulation of antioxidant enzyme-coding genes using quantitative real time RT-PCR (qRT-PCR), enzyme activity and total protein content, to understand oxidative stress responses after exposure to BPA for 48 h in brackish water flea Diaphanosoma celebensis. The BPA ($3mg\;L^{-1}$) significantly upregulated the expression of Cu/Zn-SOD, Mn-SOD, and catalase (CAT) mRNA. Three GST isoforms (GST-kappa, GST-mu, and GST-theta) mRNA levels significantly increased at the rate of $0.12mg\;L^{-1}$ of BPA. In particular, GST-mu showed the highest expression level, indicating its key role in antioxidant response to BPA. SOD activity was induced with a concentration-dependent manner, and total protein contents was reduced. These findings indicate that BPA can induce oxidative stress in this species, and these antioxidants may be involved in cellular protection against BPA exposure. This study will provide a better understanding of molecular mode of action of BPA toxicity in aquatic organisms.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.9
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• pp.255-261
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• 2019

This trial was conducted to determine the optimal supplementation level of Hermetia illucens (HI) on the growth performance, the apparent total tract retention of nutrients and the economic efficiency in weaning pigs. A total of 192 weaned pigs ($Landrace{\times}Yorkshire{\times}Duroc$; $6.51{\pm}0.15kg$) were randomly allotted to 4 treatments and 6 replicates on the basis of their initial body weight. The dietary treatments included a corn-soybean meal based diet supplemented with 0, 1, 2 or 3% HI. There were no significantly effects between the treatments in phases I, II and overall. But average daily gain was significant and linearly increased when HI was added to the diet in the overall group. Although digestibility of dry matter (DM) was increased by adding HI, digestibility responses were not observed by supplying HI in phase I. Also, all the parameters of economic efficiency were not significantly different according to the level of HI. The results showed that HI had beneficial effects on growth performance and digestibility of dry matter. However, there were no effects on economic efficiency by using HI in weaning pig diets.

• Animal Bioscience
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• v.34 no.11
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• pp.1811-1821
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• 2021

Objective: A trial was conducted to investigate the effects of supplemental levels of Mn provided by organic and inorganic trace mineral supplements on growth, tissue mineralization, mineral balance, and antioxidant status of growing broiler chicks. Methods: A total of 500 male chicks (8-d-old) were used in 10-day feeding trial, with 10 treatments and 10 replicates of 5 chicks per treatment. A 2×5 factorial design was used where supplemental Mn levels (0, 25, 50, 75, and 100 mg Mn/kg diet) were provided as MnSO₄·H₂O or MnPro. When Mn was supplied as MnPro, supplements of zinc, copper, iron, and selenium were supplied as organic minerals, whereas in MnSO₄·H₂O supplemented diets, inorganic salts were used as sources of other trace minerals. Performance data were fitted to a linearbroken line regression model to estimate the optimal supplemental Mn levels. Results: Manganese supplementation improved body weight, average daily gain (ADG) and feed conversion ratio (FCR) compared with chicks fed diets not supplemented with Mn. Manganese in liver, breast muscle, and tibia were greatest at 50, 75, and 100 mg supplemental Mn/kg diet, respectively. Higher activities of glutathione peroxidase and superoxide dismutase (total-SOD) were found in both liver and breast muscle of chicks fed diets supplemented with inorganic minerals. In chicks fed MnSO₄·H₂O, ADG, FCR, Mn balance, and concentration in liver were optimized at 59.8, 74.3, 20.6, and 43.1 mg supplemental Mn/kg diet, respectively. In MnPro fed chicks, ADG, FCR, Mn balance, and concentration in liver and breast were optimized at 20.6, 38.0, 16.6, 33.5, and 62.3 mg supplemental Mn/kg, respectively. Conclusion: Lower levels of organic Mn were required by growing chicks for performance optimization compared to inorganic Mn. Based on the FCR, the ideal supplemental levels of organic and inorganic Mn in chick feeds were 38.0 and 74.3 mg Mn/kg diet, respectively.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.35 no.2
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• pp.109-117
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• 2022

There has been an increasing number of studies on photovoltaic energy generation system in an offshore site with the largest energy generation efficiency, as increasing the researches and developments of renewable energies for use of offshore space and resources to replace existing fossil fuels and resolve environmental challenges. For installation and operation of floating photovoltaic systems in an offshore site with harsher environmental conditions, a stiffness of structural members comprising the total system must be reinforced to inland water spaces as dams, reservoirs etc., which have relatively weak condition. However, there are various limitations for the reinforcement of structural stiffness of the system, including producible size, total mass of the system, economic efficiency, etc. Thus, in this study, a floating breakwater is considered for reducing wave loads on the system and minimizing the reinforcement of the structural members. Wave reduction performances of floating breakwaters are evaluated, considering size and distance to the system. The wave loads on the system are evaluated using the higher-order boundary element method (HOBEM), considering the multi-body effect of buoys. Stresses on structural members are assessed by coupled analyses using the finite element method (FEM), considering the wave loads and hydrodynamic characteristics. As the maximum stresses on each of the cases are reviewed and compared, the effect of floating breakwater for floating photovoltaic system is checked, and it is confirmed that the size of breakwater has a significant effect on structural responses of the system.

• Journal of Korean Society of Forest Science
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• v.111 no.2
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• pp.319-329
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• 2022

Using the structural equation model (SEM), this paper investigated the relations between the recognition of forest ecosystem services and the pro-environmental behavior with personal environmental commitment and environmental consciousness. The research data was collected from April 11 to 21, 2019, as an online survey by residents in Korea. 425(91.4%) of the total 465 copies were used as final analysis data, excluding insincere responses. Results showed that most respondents recognized forest ecosystem services as positive and recognition of forest ecosystem services has a positive impact on both environmental commitment and environmental consciousness. Moreover, cultural services positively affected both constructs more than supply and control services. The most significant total effect was the path of 'cultural services-environmental commitment-pro-environmental behavior'. Environmental commitment is more effective in inducing the behavior than environmental consciousness to those who consider forest ecosystem services significant. Even if forest ecosystem services are recognized as important, those with experience of commitment to the natural environment would have more intention of pro-environmental behavior. In conclusion, this study is meaningful in that it identified the hypothesized path relationship between the recognition of forest ecosystem services and the pro-environmental behavior and analyzed the antecedent factors.

• The Korean Journal of Coaching Psychology
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• v.6 no.1
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• pp.33-55
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• 2022

This study examined the effects of 1:1 online coaching for college students on self-directed learning, learning motivation and time management. The coaching program consisted of motivation, behavior and cognitive control, which are sub-factors of self-directed learning. Total of 7 sessions(80 minutes per session) were progressed. Seven participants who wanted coaching, out of the total 16 participants, were assigned to the experimental group. A non-equal control group experimental design was applied. Dependent variables were measured by questionnaire before and after the coaching, and satisfaction survey and post-interview were also conducted after the coaching. ANCOVA was adopted to test the effectiveness of the program. The statistical results indicated that the learning coaching of this study has positive effect on self-directed learning and learning motivation of university students, and has partially positive effect on time management. In addition, the mean of satisfaction survey was 4.85 and participants showed positive responses on the program.

• Journal of the Korean Applied Science and Technology
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• v.38 no.6
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• pp.1512-1523
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• 2021

The purpose of this study was to investigate the effect of Saengmaeg-san intake on blood lipids and arteriosclerosis index in male tennis players. Seventeen male tennis players enrolled in university were assigned to a Saengmaeg-san intake group (n=9) and a placebo control group (n=8) according to whether they took Saengmaeg-san during 4-week high-intensity tennis training. Tennis training was conducted 5 times a week for 4 weeks, and the exercise intensity was performed at 70-90% of the spare heart rate. The intake of Saengmaeg-san was 110ml at a time before breakfast, before, during, during, and after exercise, and after dinner, a total of 7 times, 770ml per day. For all data, mean and standard deviation were used. Two-way repeated measures ANOVA was used to examine the effect of time and treatment, and Pearson's Correlation was used to examine the relevance of differences in blood lipid responses after treatment. As a result of this study, the Saengmaeg-san intake group significantly improved blood lipids (triglyceride, total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol) and arteriosclerosis index, and there was a significant correlation appeared between ∆TG, ∆LDL-C, and ∆TC. As a result, the intake of Saengmaeg-san during high-intensity training of male college student tennis players can have a positive effect on blood lipids and arteriosclerosis index, suggesting that it can be an effective sports drink as an exercise supplement.

• The Journal of Korean Medicine
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• v.44 no.2
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• pp.60-69
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• 2023

Objectives: This study provides basic data for activating the school doctor of Korean medicine (SDKM) program by conducting a questionnaire survey for public health doctor of Korean medicine (PHDKM) Methods: The survey questionnaire was produced by referring to the previous satisfaction survey studies for the Doctor of Korean medicine applying for the SDKM program (SDKMP). The survey questionnaire was composed of 10 questions regarding the satisfaction level, difficulties in progress, and suggestions for activation. The survey was conducted online for a total of 35 PHDKM applying for SDKMP, and 32 responses were collected. Results: Of the 32 subjects, 9 (28.1%) conducted the SDKMP. The total satisfaction level of the SDKMP was 3.69 ± 1.12 points. The lack of a standardized manual and information system was the most difficult in the program's progress (43.8%), followed by the bad cooperation of the public health centers (40.6%), and the lack of personal circumstances (40.6%). The establishment of a system to enlist cooperation with related institutions was suggested the most as a question for activating the SDKMP (71.9%), followed by the expansion of the SDKMP manual and guidance system (53.1%), and the expansion of publicity about SDKMP (37.5%). Conclusions: To activate the SDKMP in a public health environment, it is necessary to improve the system to enlist cooperation with related institutions. Also, the need to expand the standardized manual, the guidance system, and the education to PHDKM about SDKMP.

• Journal of Marine Life Science
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• v.3 no.2
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• pp.74-80
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• 2018

Mercury (Hg) poses a threat to marine ecosystem due to continuous inflow from various industries and bioaccumulation to higher trophic level via food web. Mercury can adversely affect growth, development, reproduction and metabolism to aquatic organisms. In the present study, acute toxicity and oxidative stress markers (total glutathione content, and activities of GST, GR and GPx) were investigated in brackish water flea Disphanosoma celebensis exposed to HgCl₂ for 24 h. As results, Hg showed negative effect in survival of D. celebensis. 24 h-LC₅₀ value was determined as 0.589 mg/l (95% C.I. 0.521~0.655 mg/l). After exposure to Hg (0.08 and 0.4 mg/l) for 24 h, total glutathione content was significantly decreased, whereas GST, GPx and GR activities were enhanced. These findings indicate that Hg induced oxidative stress in D. celebensis, and oxidative stress markers may be involved in cellular defense against Hg - mediated toxicity. This study provides a better understanding of molecular mode of action of Hg toxicity in this specie and potent of molecular markers for heavy metal monitoring in marine ecosystem.

• The Journal of the Korea Contents Association
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• v.22 no.5
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• pp.527-541
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• 2022

This study analyzed the structural relationship between motivation to participate in online lifelong education through YouTube, academic self-efficacy, and learning flow, where learners are rapidly increasing due to the spread of COVID-19. For this study, an online survey was conducted from July 16 to 30, 2021 for adult learners living in the metropolitan area. A total of 428 people participated in the survey, and a total of 409 copies of the results were analyzed, excluding 19 insincere responses. The main analysis results are as follows. First, The fitness of the research model was verified to be suitable for all analysis. Second, as a result of confirming the coefficients and statistical significance of each pathway in the research model, the motivation to participate in YouTube lifelong education was learning flow and academic self-efficacy, and academic self-efficacy also had a positive effect on learning flow. Third, it was confirmed that the effect of participation motivation in YouTube lifelong education on learning flow through academic self-efficacy was a statistically significant partial mediation. This study is meaningful in that it verified the structural relationship analysis between participation motive, academic self-efficacy, and learning flow in online lifelong education using YouTube reflecting the digital transformation of lifelong education due to COVID-19. Reflecting the need for re-regulation of lifelong education formed after COVID-19 and the flow of digital transformation through the research results, we discussed how lifelong education can enhance learners' motivation to participate and strengthen learning flow through academic self-efficacy as a medium.