• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.4
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• pp.1227-1240
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• 2014

Abandoned mines often cause environmental problems, such as alteration of landscape, metal contamination, and landslides due to a heavy rainfall. Geotechnical and rheological tests were performed on waste materials corrected from Imgi waste rock dump, located in Busan Metropolitan City. Debris flow mobility was examined with the help of 1-D BING model which was often simulated in both subaerial and subaqueous environments. To determine flow curve, we used a vane-penetrated rheometer. The shear stress (${\tau}$)-shear rate (${\dot{\gamma}}$) and viscosity(${\eta}$)-shear rate (${\dot{\gamma}}$) relationships were plotted using a shear stress control mode. Well-known rheological models, such as Bingham, bilinear, Herschel-Bulkley, Power-law, and Papanastasiou concepts, were compared to the rheological data. From the test results, we found that the tested waste materials exhibited a typical shear shinning behavior in ${\tau}$-${\dot{\gamma}}$ and and ${\eta}$-${\dot{\gamma}}$ plots, but the Bingham behavior is often observed when the water contents increased. The test results show that experimental data are in good agreement with rheological models in the post-failure stage during shearing. Based on the rheological properties (i.e., Bingham yield stress and viscosity as a function of the volumetric concentration of sediment) of waste materials, initial flowing shape (5 m, 10 m, and 15 m) and yield stress (100 Pa, 200 Pa, 300 Pa, and 500 Pa) were input to simulate the debris flow motion. As a result, the runout distance and front velocity of debris flow are in inverse propositional to yield stress. In particular, when the yield stress is less than 500 Pa, most of failed masses can flow into the stream, resulting in a water contamination.

• IMMUNE NETWORK
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• v.3 no.3
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• pp.211-218
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• 2003

Background: Vitamin C is an essential nutrient, taken as a daily supplement by many people. Recently, high-dose vitamin C is considered as a therapeutic regimen in some clinical situations. Until now, few studies have been done with the effects of high-dose vitamin C on the immune response. Methods: In this experiment, the effects of high-dose vitamin C on cell-mediated immune response in immunologically competent mice were evaluated. After intraperitoneal injection of 2.5, 5, or 10 mg/day of vitamin C for 10 days, delayed type hypersensitivity (DTH) was provoked against DNFB in the pinnae as a model for cell-mediated immune response. Severity of DTH reaction was evaluated as the thickness of pinnae, and the vitamin C levels were measured in the serum, liver, kidney, lung, pinnae, and splenocytes. Results: After challenge, the thickness increased at its peak on the $2^{nd}$ day in all groups. On the first day, the pinnae were thicker in the injected groups than in the control. On the contrary, the increment of the pinnae thickness was attenuated and the number of cells infiltrated in the site of DTH decreased proportionately to the amount of vitamin C administered from the second day on. With vitamin C exogenously given, the serum level peaked at 30 min after injection, and returned abruptly to its basal level without accumulation. However, it accumulated in the liver, kidney, and especially in the pinnae inflamed and splenopcytes, proportionately to the amount administered. Conclusion: Based on these results, it is suggested that, in one hand, exogenously administered high-dose vitamin C accumulated in the splenocytes and presumably changed the function of them resulting in the augmented cell-mediated immune response, as was revealed in the first day of DTH reaction. On the other hand, it seems likely that the vitamin C also showed anti-inflammatory effects.

• Journal of Digital Convergence
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• v.15 no.6
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• pp.315-327
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• 2017

This study was carried out to examine the converging factors related to academic burnout in students from health-related majors who are involved in studying for the Test of English for International Communication (TOEIC). Research subjects included 291 randomly selected students from the J-region, who were enrolled in TOEIC classes. Data collection took place from April 3, 2017 to April 14, 2017, using anonymous self-administered questionnaires. The results of a multiple regression analysis in female students showed higher academic burnout pertaining to studying for the TOEIC when sleeping hours, self-worth, self-efficacy, school adaptation resilience, and study immersion were low, and job-seeking stress and test anxiety were high. The explanatory power of this model was 65%. Based on these results, to reduce academic burnout pertaining to studying for the TOEIC in health majors, it is first necessary to increase sleeping hours, self-worth, self-efficacy, school adaptation resilience, and study immersion, and to make efforts to manage self-competence, job-seeking stress, and test anxiety. The results of this study may be used to decrease the academic burnout caused by studying for the TOEIC in health major students and to increase their aptitude for studying English, to cultivate globalized capabilities. Future studies need to conduct an effect analysis on the control and mediation effect that these factors have on academic burnout.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.27 no.5
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• pp.345-352
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• 2014

In this paper, the CAD data for the optimal shape design obtained by isogeometric shape optimization is directly used to fabricate the specimen by using 3D printer for the experimental validation. In a conventional finite element method, the geometric approximation inherent in the mesh leads to the accuracy issue in response analysis and design sensitivity analysis. Furthermore, in the finite element based shape optimization, subsequent communication with CAD description is required in the design optimization process, which results in the loss of optimal design information during the communication. Isogeometric analysis method employs the same NURBS basis functions and control points used in CAD systems, which enables to use exact geometrical properties like normal vector and curvature information in the response analysis and design sensitivity analysis procedure. Also, it vastly simplify the design modification of complex geometries without communicating with the CAD description of geometry during design optimization process. Therefore, the information of optimal design and material volume is exactly reflected to fabricate the specimen for experimental validation. Through the design optimization examples of elasticity problem, it is experimentally shown that the optimal design has higher stiffness than the initial design. Also, the experimental results match very well with the numerical results. Using a non-contact optical 3D deformation measuring system for strain distribution, it is shown that the stress concentration is significantly alleviated in the optimal design compared with the initial design.

• Journal of dental hygiene science
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• v.14 no.4
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• pp.554-562
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• 2014

This study was conducted to identify the factors influencing toothbrushing behaviors of elementary school students by adding the variable of 'self-efficacy' to the behavioral model based on the theory of planned behavior. To collect the data for an analysis, the self-administered questionnaire was distributed to 443 students in 4th to 6th grades of elementary school placed in Inchon Metropolitan City. The statistical package of PASW 18.0 was employed for the analysis. Results of the analysis revealed that the toothbrushing intention was explained by the subjective norm (${\beta}=0.343$), the self-efficacy (${\beta}=0.171$), the perceived behavioral control (${\beta}=0.163$), and the attitude toward the tooth-brushing behavior (${\beta}=0.135$). The toothbrushing behavior was explained by the toothbrushing intention (${\beta}=0.355$) and the self-efficacy (${\beta}=0.113$). The synthesis of such results suggested that both parents and teachers in school who would be influential to students should guide elementary school students to be habituated to the right toothbrushing. Also it was estimated that the students should understand the importance of toothbrushing through proper oral health education, and they should also become confident in spontaneous toothbrushing by providing them with an environment that could help them practicing the toothbrushing easily.

• Progress in Medical Physics
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• v.20 no.1
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• pp.43-50
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• 2009

The 4 bank mico-MLC (mMLC; Acculeaf, Direx, Isral) has been commissioned for clinical use of linac based stereotactic radiosurgery. The geometrical parameters to control the leaves were determined and comparisons between measured and calculated by the calculation model were performed in terms of absolute dose (cGy/100 MU). As a result of evaluating calculated dose for various field sizes and depths of 5 and 10 cm in water in the geometric condition of fixed SSD (source to surface distance) and fixed SCD (source to chamber distance), most of differences were within 1% for 6 MV and 15 MV x-rays. The penumbral widths at the isocenter were approximately evaluated to 0.29~0.43 cm depending on the field size for 6 MV and 0.36~0.51 cm for 15 MV x-rays. The average transmission and leakage for 6 MV and 15 MV x-rays were 6.6% and 7.4% respectively in single level of leaves fully closed. In case of dual level of leaves fully closed the measured transmission is approximately 0.5% for both 6 MV and 15 MV x-rays. Through the commissiong procedure we could verify the dose characteristics of mMLC and approximately evaluate the error ranges for treatment planning system.

• Korean Journal of Social Welfare
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• v.61 no.4
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• pp.307-332
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• 2009

This study is about the development and effectiveness of the 'Empowerment Program' for the persons with disabilities caused by industrial accidents. The program was developed on the basis of the analysis of focus group interviews for the rehabilitation counselors who work with the persons with disabilities caused by industrial accidents. Also, it was based on Miley et al's empowerment model and the group social work practice. The goal of the program was to strengthen the level of empowerment and decrease emotional frustration for the persons with disabilities caused by industrial accidents. The program consisted of two different types: one for the hospitalized person and the other for the discharged person. The program practiced once a week for 6 weeks and 8 weeks by the choice of the rehabilitation counselors. In order to verify the effectiveness of the program, the participants included 11 persons for the experimental group and 10 persons for the control group. The empowerment scores of the two groups were estimated at the point of pre-test and post-test and were analysed through the Wilcoxon signed rank test and Mann-Whitney U test. As the results of the analyses showed, there were significant differences in the increases in the areas of total empowerment and self-image as a sub-scale between the two groups. In conclusion, the effectiveness of the program was confirmed. Also, it has been verified that the program can be an important social work practice tool for strengthening the empowerment level of the persons with disabilities caused by industrial accidents.

• Journal of Korean Society of Forest Science
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• v.101 no.2
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• pp.185-194
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• 2012

The purpose of this contribution is to develop the framework of a methodology for identifying potential errors in georeferencing and in an application of it using specimens of Ox-Knee, Achyranthes bidentata Blume in Korea. At infraspecific level, uncertainty of identification showed that 41% of A. bidentata var. japonica and 28% of var. bidentata were misidentified, suggesting that the uncertainty level was independent of the reliability of experts' identification. For georeference specimen records, 71 specimens out of total 303 were selected and utilized as occurrence data: Uncertainty was 32.4 km at maximum and was 0.1297 km at minimum (mean = 4,055 m, s.d. = 5,772 m). Var. japonica is common throughout most of the southeastern Korea and west coastal areas, while var. bidentata has been found as far north as Gyeonggi and Gangwon provinces. We modelled the potential distribution of two varieties using Bioclim approach in Korea based on several environmental factors. Our results indicated the most important region for var. japonica lies the west coast ranges and southern area, while for Chungcheongnam-do of potential high diversity occurs for var. bidentata. This study shows that the major factors to determine the distribution patterns of two varieties were thermal factors, rather than precipitation. The Bioclim model using geocode and georeferencing data makes the information increasingly useful and reliable. To improve data quality, it requires full management from data collection to final databases including data cleaning.

• Journal of the Korean earth science society
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• v.26 no.7
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• pp.611-623
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• 2005

The purpose of this study is to explore the effects of self-directed field learning practices on student’s academic achievement and self-directed learning characteristics regarding the level of learning ability. To conduct this study, 196 students of high school students in Busan were chosen and parted into either the experimental group (98 students) or control group (98 students). Each group is classified into three categories: high level (24 students), middle level (50 students), and low level (24 students) according to the level of learning ability by the academic achievement pre-test. The areas chosen for experimenting this study range from Dusong peninsula, Molundae in Saha-gu, Songdo in Seo-gu, Pusan. Then the inquiry-model of self-directed field learning which focuses on learner-centered activity was designed based on theories concerning field learning and self-directed learning, and was applied to the experimental group. In conclusion, this teaching method using self-directed field learning is expected to improve academic achievement in science subject and increase students’ self-directed learning characteristics regardless of the students' level of academic achievement.

• Journal of Environmental Science International
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• v.29 no.10
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• pp.989-996
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• 2020

This study was conducted to determine the effect of low temperature and low radiation conditions on the yield and quality of hot pepper at an early growth stage in Korea. In plastic greenhouses, low temperature, low temperature with covered shading treatments were set 17 to 42 days after transplanting. The pepper growing degree days decreased by 5.5% due to the low temperature during the treatment period. Radiation decreased by 74.7% due to the covered shading. After commencing treatments, pepper plant growth decreased with low temperature and low radiation. Analysis of the yield showed that the first harvest was delayed by low radiation. The cumulative yields of 119 days after transplanting were 1,956, 2,171, and 2,018 g/㎡ for control, low temperature, and low temperature with low radiation respectively. Capsaicin and dihydrocapsaicin concentrations in pepper fruit decreased with low temperature and low radiation. To investigate the photosynthetic characteristics according to the treatment, the carbon dioxide reaction curve was analyzed using the biochemical model of photosynthesis. Results showed that the maximum photosynthetic rate, V_cmax (maximum carboxylation rate), J (electric transportation rate), and TPU (triose phosphate utilization) decreased at low temperatures; the maximum photosynthetic rate, J, and g_m (dark respiration rate) were reduced by shading. These results indicate that low temperature and low radiation can retard early growth, yield, and quality, but these can also be recovered 119 days after planting. Based on the results, the yield and quality of pepper can recover from abiotic stresses with proper cultivation.