• Journal of the Korea Concrete Institute
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• v.21 no.4
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• pp.457-464
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• 2009

Fiber is an important ingredient in fiber-reinforced cement composite (FRCC) which can control fracture of cement composite by bridging action. In compliance with the action of the fiber and the aggregate size, it also showed a different failure mechanism. For practical application, it is needed to investigate the fracture behavior of the FRCC and to understand the micro-mechanism of cement matrix with reinforcing fiber. In order to evaluate a characteristics of fracture process in the FRCC, acoustic emission (AE) technique was used for the analysis and evaluation of FRCC damage by acoustic emission under flexural and cyclic compressive loadings. The AE signals were monitored by AMSY4 AE instrument during the entire loading period. The specimens are reinforced with 0, 1.0, 1.5 and 2.0% (by volume) Polyvinyl alcohol (PVA) fiber. The test results showed that the damage progress of the FRCC was characteristic for the fiber replacement ratio. As a result of analyzing the felicity ratio (FR) values, it is shown that this values can be used for evaluating the degree of FRCC damage. On the whole the felicity ratio values of FRCC are shown between 0.4 and 1.1. And, the AE kaiser effect was shown in the all FRCC specimen. In addition, the damage behavior and the microscopic fracture process of the FRCC are evaluated using the AE parameters, such as calm ratio, b-value and felicity ratio. The purpose of this reserch was to advance the state of knowledge regarding the applicability of acoustic emission as an evaluation method for FRCC.

• Korean Journal of Occupational Therapy
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• v.26 no.4
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• pp.43-55
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• 2018

Objective : The purpose of this study was to investigate the effects of fidget spinner training on the hand function and handwriting legibility of lower grade elementary school studens. Methods : This study randomly assigned a study group of 12 children and control group of 12 children from 24 children in grade 1 and 2 (ages 7 through 8), whose are dominantly right handed. The study used was a pre-post process. The intervention was conducted only on the study group twice a week for 5 weeks and for 40 minutes per session, for a total of ten sessions. The measuring instruments used to compare the hand functions and handwriting legibility were the Jebsen-Taylor Hand Function Test, Grip Strength Test, and Legibility Test. The data analysis used a Wilcoxon signed rank, Mann-Whitney U and Chi-Square cross analysis. Results : The fidget spinner training showed significant improvement in the study group's hand function(grip strength and handwriting legibility) and a significant difference was shown between the control and study groups. Conclusion : This study confirmed the value and utility of a fidget spinner as a tool for improving the hand function and handwriting legibility of elementary school students in lower grades. Future studies are expected to verify the effectiveness of the fidget spinner training based on the present study.

• The Journal of the Korea Contents Association
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• v.17 no.2
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• pp.449-466
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• 2017

This research is to find structural relationships among psychological anxiety, appearance-oriented attitude, and self-esteem of youth and investigates how the structural relationships show by genders and different school classes. For the investigation, a collected data for the research of 'adolescent's misbehaviors and tendency of their young average age and political subject' were used from SPSS 22.0 program and AMOS 22 statistical program provided by Korea youth and children's data archive. First of all, the research determines as the psychological anxiety gets higher, youth have lower self-esteem level and more behavior problems. In addition, when adolescents show stronger appearance-oriented attitude they have higher self-esteem level and more behavior problem. The study also indicates that as youths have higher self-esteem their behavior problem levels are reduced. Secondly, by examining the relationships of youth's psychological anxiety and appearance-oriented attitude based on their self-esteem, the self-esteem gives a positive mediated effect on psychological anxiety and behavior problem whereas the self-esteem affects as negative mediated effect on the appearance-oriented attitude and behavior problem. Lastly, the study indicates there is a causal interaction between youth's appearance-oriented attitude and behavior problem which differs by genders and different school classes. Based on the results of the research, the theoretical and practical applications were suggested to prevent and relax the adolescent's behavior problems.

• 한국해양학회지
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• v.27 no.3
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• pp.210-227
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• 1992

KODOS-89 area, the northwestern part of Clarion-Clarion-Clipperton fracture zones in the Northeast Pacific, was surveyed in order to study the occurrence and distribution of manganese nodules. Variations in the nodule characteristics are related mainly to seafloor topography. Nodules from abyssal plain have high Mn/Fe ratio and high Mn, Cu, Ni and Zn concentrations, whereas those from seamount are characterized by low Mn/Fe ratio and high Fe and Co concentrations. These compositional characteristics are attributed to toxic diagnosis and hydrogenesis, respectively. Nodules of the early diegenetic origin tend to accurate crystalline Mn-oxides uniformly within the topmost sediment layers and maintain a regular spheroidal, ellipsoidal to discoidal shape with rough surface textures. On the other hand, those of hydrogenetic origin are characterized by polynucleation, irregualr shape, and smooth surface textures. Nodule abundance is high (avg. 13.4 kg/m$^2$) in seamount area, resulting from ample supply of nucleating materials by auto-fragmentation of older nodules. Nodule abundance in abyssal plain is relatively low (avg. 3.9 kg/m$^2$) and tends to increase southward. This phenomenon results from facilitation of taking seed materials from adjacent seamount and enhancement of the early diagenesis by sufficient supply of organic materials. Nodule abundance is considered to be controlled primarily by seeding effects and secondly by supplies of organic materials.

• Journal of Life Science
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• v.34 no.7
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• pp.485-492
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• 2024

Sea cucumbers contain more than 50% protein in their solid content, and they also possess various bioactive substances such as saponins and mucopolysaccharides. This study analyzed the activities of various enzymes derived from Bacillus and lactic acid bacteria and determined to degrade the components of sea cucumbers. Among the analyzed strains, B. subtilis K26 showed the highest activities in protease and xylanase and relatively high activity in cellulase. Accordingly, samples of sea cucumber and water were mixed in equal proportions, sterilized, and then fermented by inoculating them with B. subtilis K26. Following this, a higher amino acid content was observed between 1.5 and 7.5 hr, a lower residual solid content in this time, and a lesser fermentation odor. The saponin content in fermented sea cucumber powder extracted with butanol was measured to be 1.12 mg/g. The chondroitin sulfate content was evaluated to be 5.11 mg/g in raw sea cucumber. The total polyphenol content, flavonoid content, and antioxidant activities were 6.95 mg gallic acid equivalent/g, 3.69 mg quercetin equivalent/g, and 3.69 mg quercetin equivalent/g in raw sea cucumber, respectively. Moreover, the DNA damage protective effect of fermented sea cucumber extract was found to be concentration-dependent, with a very strong effect at very low concentrations. Overall, we suggest that sea cucumber fermented with B. subtilis K26 has a high potential as a food for inhibiting oxidation, enhancing immunity, and improving muscle function in the human body thanks to its high free amino acid content.