• Journal of Korean Tunnelling and Underground Space Association
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• v.17 no.2
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• pp.75-90
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• 2015

As soil nails support a ground by the friction between nails and soils being reinforced, the length of soil nails is important factor for a ground stability. Thus, the soil nail length has to be accurately evaluated in order to secure a ground stability. The goal of this study is to suggest the applicability of the non-destructive method as the basic research for the evaluation of the soil nail length. First, the elastic and electromagnetic waves are adopted to select an applicable method for the soil nails connected by the coupler. Test results show that while the ultrasonic waves are not detected due to the coupler, the electromagnetic waves are free for the influence of the coupler. Second, electromagnetic waves are measured for combined soil nails with the length of 1 m~15 m for the investigation of the characteristics of electromagnetic waves. The travel time of the electromagnetic wave increases with an increase in the soil nail length. In addition, the ground cable is used to apply the electromagnetic waves to pre-installed soil nails. Test results show that the travel time of the electromagnetic wave by using the ground cable increases with an increase in soil nail length. This study demonstrates that the electromagnetic wave may be a promising method for the evaluation of the soil nail length.

• Polymer(Korea)
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• v.29 no.4
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• pp.403-407
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• 2005

In this work, the solid polymer electrolyte (SPE) composites, which are composed of poly(ethylene oxide) (PEO), mesoporous mobil crystalline material-41 (MCM-41), and lithium salt, are prepared in order to investigate the influence of MCM-41 contents on the ionic conductivity of the composites. The crystallinity of the SPE composites was evaluated using differential scanning calorimeter (DSC) and X-ray diffraction (XRD). The ionic conductivity of the SPE composites was measured by the frequency response analyzer (FRA). As a result, the addition of MCM-41 into the polymeric mixture prohibited the growth of PEO crystalline domain due to the mesoporous structures of the MCM-41. The $P(EO)_{16}LiClO_4$/MCM-41 electrolytes show an increased ion conductivity as a function of MCM-41 content up to 8 $wt\%$ and a slightly decreased conductivity over 8 $wt\%$. These ion conductivity characteristics are dependent on a change of polymer crystallinity in the presence of MCM-41 system.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.24 no.6
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• pp.413-427
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• 1991

Variability of sea levels at Mukho and Ullungdo and sea level difference(SLD) associated with current is investigated. Time series of adjusted sea levels at both places have very similar pattern of change. Two components appear to contribute to the correlation between sea level and SLD. Low frequency thermosteric effect causes the sea level to rise and fall at the same time. Geostrophic effect of major currents is responsible for the sea level change in opposite ways at both sides. Two contributions have a cancelling effect for sea level change at Mukho while they are additive at Ullungdo. Characteristics of time series in frequency domain are divided into two parts with respect to 0.01 cycles per day(cpd). At Mukho, the cancelling effect yields small values of coherence for low-frequency bands whereas the dominant geostrophic influence may be responsible for the phase relations of about $\pm 180^{\circ}$ between sea level and SLD at higher frequency. Bimonthly dynamic height difference(DHD) between Mukho and Ullungdo is very significantly correlated with SLD. This result suggests that DHD thus the average velocity of current through the Mukho-Ullungdo section can successfully be diagnosed by the sea level records at both locations. For the annual variations, maximum SLD occurs at Mukho-Ullungdo section about 40 days later than the Korea Strait.

• School Mathematics
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• v.16 no.1
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• pp.157-180
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• 2014

This study investigated relationships between academic stress and mathematics learning motivation focusing on the mediating effect of academic motivation types. It also tested differential structural relationship among the variables in the high vs. low academic achievement level groups and the boys vs. girls of middle schools. The participants were 952 second graders from five middle schools. Student scores from the standardized tests that were developed to assess the students' academic stress, mathematics learning motivation, and three types of motivation (amotivation, controlled motivation, and autonomous motivation) were used in this study. The results demonstrate that there were significant differences in the relationship patterns of the research variables. Correlation analysis provided evidences that academic stress was negatively related with mathematics learning motivation and autonomous motivation but positively related with amotivation and controlled motivation. Also, mathematics learning motivation was negatively related with amotivation and controlled motivation but positively related with autonomous motivation. Structural equation modelling analysis provided the evidence that the full mediation model was a significant, in that the students' types of academic motivation mediated the effect of academic stress on mathematics learning motivation. Multiple group analysis revealed that there were group differences in the path coefficients of the structural model. But the academic stress showed negative influence on the mathematics learning motivation via amotivation and autonomous motivation in all groups.

• Journal of the Korean Society for Library and Information Science
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• v.41 no.4
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• pp.93-111
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• 2007

The Internet is now an integral part of the everyday lives of a majority of people. Web users are becoming increasingly skeptical of the information and services offered online. They are demanding web sites that offer credible information. This study focused on what features of web sites affect the perception of web credibility. For this purpose, I took the responses from 648 people and extracted 49 factors that affect web credibility. I placed the individual factors - the specific questions asked in the survey - into one of four categories expertise. trustworthiness, ads and other and calculated the means for each of the 49 factors. As a result, 29 out of 49 factors increase the Perceptions of credibility and 20 factors decrease the web credibility. Sites with frequently update. the credentials of authors, strict content guides, search capabilities, clear connections to the real world fared good in credibility. Technical problems such as broken links, site sown, or typographical errors were rated the most negative on this scale On the other end of the scale, a domain name that ends in' .org' or' .or.kr' caused little change in perception of credibility.

• Physical Therapy Korea
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• v.24 no.1
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• pp.51-60
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• 2017

Background: In cerebral palsy (CP), parents' quality of life and rearing attitude are considered possible factors that influence patients' quality of life, function level, and performance in daily activities. Despite these facts, little attention has been given to demonstrate a relation between these factors. Objects: This study aimed to demonstrate the relationship between parents' quality of life, functional level, and performance in daily activities, the quality of life of school-aged children with spastic CP. Methods: This study included 24 parents of school-aged children with spastic CP. The KIDSCREEN-52 and World Health Organization quality of life (WHOQOL)-BREF questionnaires (including physical, psychological, social, and environmental domains) were used as research tools to assess the quality-of-life profiles of the children with spastic CP and those of their parents, respectively. In addition, the function levels and performance in daily activities of the children with CP were assessed by using the gross motor function measure (GMFM) and modified Barthel index (MBI). Correlation and multiple regression analyses were performed to clarify the determinants of the quality of life of the children with CP. Results: The KIDSCREEN-52 score correlated with the total score (r=.735, p<.01) and all domains of the WHOQOL-BREF questionnaire (physical: r=.542, p<.01; psychological: r=.690, p<.01; social: r=.568, p<.01; and environmental: r=.783, p<.01). In addition, significant correlation was found between the KIDSCREEN-52 and MBI scores (r=.411, p<.05), and between the MBI and GMFM scores (r=.427, p<.05). After controlling for age, gender, paralytic type, GMFM, and MBI, the WHOQOL-BREF score ($R^2=.621$), particularly in the environmental domain ($R^2=.699$), remained independently related to the quality of life of the children. Conclusion: These findings suggest that the quality of life of school-aged children with spastic CP can be influenced by the quality of life of their parents. This study provides useful information for future studies to investigate the quality of life of children with CP.

• Journal of the Korean Society for Railway
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• v.19 no.1
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• pp.38-45
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• 2016

The power transformation system of High Speed rolling stocks like KTX-Sancheon has shown excellent control capacities in the areas of riding comfortability, switching efficiency, safety and energy consumption due to technical developments in power-electronics, high speed & large scale integrated semiconductors and microprocessors. However, harmonics from IGBT, a high speed switching device used in the Convertor & Invertor equipment of rolling stocks have given rise to various problems in transformer substations, signaling systems, data transmission systems and facility monitoring systems. Especially, TI21 non-insulated track circuits have malfunctioned due to the influence of returning current harmonics which were generated at around of integer times of the number of power transformation equipment in the frequency domain. This paper, measures and analyzes various schemes to analyze the traveling path of the returning current harmonics generated due to the relationship between the rolling stocks and track circuits on site. Ultimately, theseschemes will be used to design high speed rolling stocks, AF track circuits and a common grounding network.

• Asia pacific journal of information systems
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• v.10 no.2
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• pp.71-95
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• 2000

Despite repeated exhortation about the importance of social and human dimensions of systems development, socio-organizational issues continue to be neglected and ignored in the current information systems practice. A review of the human information processing literature suggests that the reasons for this continuing lack of attention to social issues may be found in the limitations of human cognition and information processing capacities. Bostrom and Heinen(1978) and Kumar and Bjorn-Anderson(1990) also suggest that the inadequate attention to social problems and issues by the analyst could originate from the analysts limited problem perception. This research explores how the representation forms of information systems(IS) methodology used in understanding and modeling the problem situation affect such systems development problem perception. Typically, a system development methodology prescribes the use of system models(i.e., system representations) to understand, analyze, evaluate, and design the information system. Given the size and complexity of information systems, and the abstraction and simplification underlying the modeling process, system representations usually depict only a limited set of aspects of the system. Thus, a methodology whose representations are limited to technical aspects will tend to limit the analyst's perspective to a technical one only(Kumar & Welke, 1990). Following the same line of argument, in contrast, it is the conjecture of this study that a methodology which specifies both social and technical aspects of IS development will help the analyst develop a more comprehensive view of the IS problem domain. Based on the above concept, a theoretical model was first developed which explained the systems analysts cognitive process. Drawing on this model, a research model was developed hypothesizing the impacts of representation forms on problem identification. The model was tested using a laboratory experiment with 70 individual subjects. A special computer software was developed with a hypermedia authoring tool to conduct the experiments in order to avoid experimenter biases and to maintain consistency in administrating repeated experiments. The program, designed to replace the experimenter, consisted of functions such as presenting the subjects with problem material, asking the subjects questions, and saving the typed answers of the subjects. The results indicate that representation forms strongly influence problem identification. It was found that the use of the socio-technical representation form led to the findings of more social problems than the use of technical representation form. The results imply significant effects of representation forms on problem findings and also suggest that the use of adequate representation forms may help overcome dysfunctional effects of our limited information processing capacity.

• Geophysics and Geophysical Exploration
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• v.11 no.2
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• pp.93-98
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• 2008

Abstract: Surface topography has a significant influence on seismic wave propagation in a reflection seismic exploration. Effects of surface topography on two-dimensional elastic wave propagation are investigated through modeling using a weighted-averaging (WA) finite-element method (FEM), which is computationally more efficient than conventional FEM. Effects of air layer on wave propagation are also investigated using flat surface models with and without air. To validate our scheme in modeling including topography, we compare WA FEM results for irregular topographic models against those derived from conventional FEM using one set of rectangular elements. For the irregular surface topography models, elastic wave propagation is simulated to show that breaks in slope act as a new source for diffracted waves, and that Rayleigh waves are more seriously distorted by surface topography than P-waves.

• Journal of The Korean Association For Science Education
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• v.34 no.6
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• pp.593-599
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• 2014

The purpose of this study is to figure out the influence on the students' achievement of the cognitive and the affective domains by descriptive items assessment of teacher or peer and to obtain implications by analyzing the students' satisfaction and the reliability of the assessment. For this purpose, two classes of 11th grade students located in a small city were selected and took an exam related to the cognitive and the affective domains before and after the assessment. The assessment activities were carried out during 10 lessons and the teacher gave feedback to the students of the teacher assessment class in the lessons. In the peer assessment class, a small-size student group discussion and feedback were given to the students after the exam. The results show that higher level achievement group students represented relatively positive satisfaction on teacher assessment, and lower level achievement group students represented positive satisfaction on peer assessment. In spite of the same marker list, higher level achievement group students represent relatively high reliability than lower level achievement group students. The lower level achievement group students in the peer assessment class got statistically meaningful improvement of achievement than the students of teacher assessment class. The peer assessment activity was positively influenced on the affective domain of the lower level achievement group students, especially signigicant meaning of statistics was found on the students' perception about science.