• Steel and Composite Structures
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• v.26 no.1
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• pp.1-15
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• 2018

This study reported, the effect of random variation in system properties on bending response of single wall carbon nanotube reinforced composite (SWCNTRC) plates subjected to transverse uniform loading is examined. System parameters such as the SWCNT armchair, material properties, plate thickness and volume fraction of SWCNT are modelled as basic random variables. The basic formulation is based on higher order shear deformation theory to model the system behaviour of the SWCNTRC composite plate. A C0 finite element method in conjunction with the first order perturbation technique procedure developed earlier by the authors for the plate subjected to lateral loading is employed to obtain the mean and variance of the transverse deflection of the plate. The performance of the stochastic SWCNTRC composite model is demonstrated through a comparison of mean transverse central deflection with those results available in the literature and standard deviation of the deflection with an independent First Order perturbation Technique (FOPT), Second Order perturbation Technique (SOPT) and Monte Carlo simulation.

• Journal of the Korean Society for Advanced Composite Structures
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• v.3 no.2
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• pp.36-46
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• 2012

Structure Insulated Panel (SIP) is an wooden structure material with which structure and insulation functions are satisfied. Hence, it would be a cost-effective model to implement low energy house which has higher insulation and structure performance and which the wall thickness is able to be reduced. In this study, performance of thermal insulation and fire resistance were evaluated in order to verify applicability to low energy house. Fire resistance test is performed on vertical load bearing members for partitions, and the test results satisfy one hour of fire resistance condition according to KS F 2257. The members include two layers of fireproof gypsum board with thicknesses of 12.5mm attached to SIP. Thermal insulation performance is satisfied with the 2012 standard ($0.225W/m^2{\cdot}K$). As the performance of resistance and thermal insulation are satisfied, SIP is expected to be applied to low energy building materials. In the future, the structural safety will be confirmed by structural performance and seismic performance test and the guidelines for distribution will be drawn up.

• Journal of dental hygiene science
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• v.21 no.2
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• pp.79-85
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• 2021

Background: This study examines the relationship between the emotional labor and compassion competence of clinical dental hygienists. It attempted to provide basic data to establish a plan to increase the dental hygiene performance of clinical dental hygienists in the future by identifying the factors influencing the dental hygiene work performance. Methods: This study is aimed at clinical dental hygienists working at the Jeollabuk-do Dental Clinic from April to June 2020 by the Convenience Sampling Method. An online survey site program was used to explain the purpose and purpose of the study on social media including the dental hygienist community, and distribute a URL that allows you to participate in the survey only if you agree to the study. Results: In emotional labor, there was a significant difference in job satisfaction and marital status, and in compassion competence, there were significant differences in job satisfaction, final education, and marital status by group. In dental hygiene work performance, compassion competency showed a statistically significant positive correlation. In other words, it was found that the higher the compassion competence, the higher the dental hygiene work performance. It was found that the total number of years worked and the compassion competence that influenced dental hygiene work performance were statistically significant. Conclusion: In summary, in order to improve the dental hygiene work performance of clinical dental hygienists, it is necessary to compassion competence with the subject. To this end, it is believed that various supports, measures, and systematic management should be implemented to compassion competence of clinical dental hygienists.

• Journal of the Korean Society for Library and Information Science
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• v.13
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• pp.95-119
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• 1986

The objective of this study is to search for a theoretical and practical solution to the question of what is the most effective and qualitative method of information service for the college and university libraries in Korea. Assuming the maximum service or total service theory in information services, therefore, it appears natural that the subject specialist who is highly knowledgeable in his subject is indispensable in raising the quality of information librarians. The procedure of this research was as follows: There was no college and university library employing any full-time subject spceialist in Korea. This research, however, was proceeded on the assumption that subject specialists are already employed in all of the college and university libraries after the subject specialist system is established. The least qualification of subject specialist is limited, based on the criteria given by the foreign literature, to those who have master's degree in Library Science and bachelor's degree in any other subject area, those who have bacholor's degree in Library Science and master's degree in any other subject area, or those who have both bacholor's and master's degrees in Library Science with minor in any subject field . To prove the research hypothesis that the subject specialist will perform his role more efficiently than the generalist in effectively providing information service based on both accuracy and speed, this research as an obtrusive testing method analyzed the effectiveness by presenting information questions to the generalists and subject specialists who are information librarians in college and university libraries. For this study 20 librarians working at 12 university libraries were tested for performance levels of information services. The result showed $59.75\%$ an absolute performance rate and $75.20\%$ an adjust performance rate. Compared to Thomas Childer's 1970 study in which he used the unobtrusive testing method, these results were $5\%$ higher in the absolute performance rate and $11.36\%$ higher in the adjust performance rate. In comparing the generalist with the subject specialist in efficiency of information service, while the absolute performance rate was $57.08\%$ and the adjust performance rate was $73.08\%$ in the case of the generalist, the absolute rate was $63.75\%$ and the adjust rate was $78.38\%$ in the case of specialist, therefore, the efficiency of the subject specialist was $6.67\%$ higher in the absolute performance rate and $5.30\%$ higher in the adjust performance rate than that of generalist. But the factor of speediness was excluded from the analysis because of the difference between the time the interviewers recorded and the time the interviewee recorded. On the basis of the result of this research, it should be desirable to educate subject specialists and employ them as information librarians and for them to function as efficient subject specialists in order to improve the effectiveness of information services, the nucleus of the raison d'etre of college and university libraries.

• Journal of Environmental Science International
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• v.11 no.1
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• pp.75-83
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• 2002

The removal performance of copper ion was studied using Na-P1 zeolites synthesized from Jeju scoria. The scoria which is found in large amounts in Jeju Island, was sampled at four regions, Jeju-shi Bonggae-dong(A). Pukcheju-gun Hanlim-eup Sangmyong-ri Mangoreum(B), Pukcheju-gun Hanlim-eup Keumag-ri(C) and Namcheju-gun Andeok-myun Dongkwang-ri(D). Synthetic Na-P1 zeolites used in this study were more effective than natural zeolite and scoria for the removal of copper ion. The removal performances of copper ion decreased in the order of Na-P1(D) > Na-P1(C) > Na-P1(B) > Na-P1(A) among Na-P1 synthesized from the scoria according to region. These results showed the same trend with cation exchange capacity(CEC) for each synthetic zeolite, i.e., the synthetic Na-P1 zeolite with a higher CEC showed a higher removal performance. The effective diffusion coefficients of copper ion by synthetic Na-P1 zeolites were one hundred and ten times higher than those by a pure zeolite 4A and the zeolite A synthesized from coal fly ash, respectively.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.8 no.1
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• pp.7-12
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• 2012

This study proposes a hybrid geothermal system combined with heating mode and snow-melting mode for winter season in order to increase the annual operating efficiency of the GSHP(Ground Source Heat Pump). The purpose of this study is to get effectiveness of the hybrid geothermal system by the site experiments. In case of snow-melting only mode, the GSHP COP is 0.7 higher than system COP in average. And in case of hybrid mode, heating GSHP COP is 0.5 higher than snow-melting GSHP COP. And it is also found out that all COP obtained through measurement periods is higher than nominal COPs given by GSHP manufacturer. As a conclusion, it is clear that the proposed hybrid geothermal system is expected as a highly efficient system.

• International Journal of Fluid Machinery and Systems
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• v.8 no.1
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• pp.1-12
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• 2015

In cardiopulmonary support systems with a membrane oxygenation such as a percutaneous cardiopulmonary support (PCPS) or an extracorporeal membrane oxygenation (ECMO), blood pumps need to generate the pressure rise of approximately 200mmHg or higher, due to the high hydraulic resistances of the membrane oxygenation and of the cannula tubing. In order to realize the blood pump with higher pressure rise, higher anti-hemolysis and thrombosis performances, the development of novel centrifugal blood pump composed of two-stage has been conducted by the authors. In the present paper, effective attempts to decrease the wall shear stress and to suppress the stagnation are introduced for the prevention of hemolysis and thrombosis in blood pumps. The hemolysis test was also carried out and it was clarified that the decrease of wall shear stress is effective as a guideline of design of blood pumps for improving the anti-hemolysis performance.

• Nuclear Engineering and Technology
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• v.56 no.6
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• pp.2395-2403
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• 2024

With the rapid development of DC high voltage accelerator, higher requirements have been raised for the design of DC high voltage power supply, requiring more stable high voltage with lower output ripple. Therefore, it also puts forward higher requirements for the parameter design of the voltage doubling rectifier circuit, which is the core component of the DC high voltage power supply. In order to obtain output voltage with better performance, the effects of the working frequency, the stage capacitance and the load resistance on the output voltage of the voltage doubling rectifier circuit are studied in detail by simulation. It can be concluded that the higher the working frequency of the transformer, the larger the stage capacitance, the larger the load resistance and the better the output voltage performance in a certain range. Based on this, a 2.5 MV voltage doubling rectifier circuit driven by a 120 kHz frequency transformer is designed, developed and tested for the power supply of the neutron source device towards BNCT. Experimental results show that this voltage doubling rectifier circuit can satisfy the design requirements, laying a certain foundation for the engineering design of DC high voltage power supply of neutron source device.

• Journal of Korea Trade
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• v.24 no.6
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• pp.173-193
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• 2020

Purpose - This study aims to examine the effect of entrepreneurship of start-ups on export performance when the business closure rate is higher than business start-up rate in Korea. Thus, this study analyzes various factors for start-ups established within the past seven years and uses export performance as an indicator. Prior to analysis of factors, the study defines the concepts of start-up factors based on various studies. Design/methodology - In order to analyze the export performance of startups, this study conducted an empirical analysis using statistical analysis. Theories were established based on previous studies, and hypotheses and research models were designed based on the established theories. Subsequently, in order to verify the research hypothesis and research model, factor analysis such as validity and reliability, and structural equation modeling were analyzed. Findings - As a result of analysis based on previous studies, we found that there is a difference between theoretical and practical aspects. Whereas previous studies showed that market orientation, technology orientation, and social capital have a direct impact on export performance, the present study analyzed that there is no such impact, and that technology capabilities were important as a result of the unique traits of start-ups. Originality/value - Existing studies have limitations in understanding the overall characteristics of a company by using market orientation, technology orientation, and social capital as individual independent variables. In addition, the existing researches have been analyzed in relation to corporate performance, whereas this study has been limited to export performance, so it can be regarded as different from other studies.

• Journal of the Korean Society of Clothing and Textiles
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• v.18 no.1
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• pp.81-90
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• 1994

The purpose of this study is to understand the types of risk consumers feel when they shop at home and to compare their feelings with the perceived risk when they shop at stores and the kinds of clothing frequently purchased at home. For this study, the data were collected through the questionnaire distributed to 692 carried and unmarried women. The analysis was done through the t-test, ANOVA and regression. The results are as follows . 1) Compared to those shopping at stores, at-home shoppers perceived a higher risk in eight kinds of clothing. 2) Compared to shopping at stores, product performance risk, psychological risk and time loss risk increased dramatically Among these, the time loss risk showed the most noticeable increase. 3) When the perceived risk was low for a certain item, it was more often shopped at home. Among the perceived risk types, the lower the financial risk and the time loss risk, the item was more frequently shopped at home. 4) Together with store shopping, the perceived risks when shopping at home differed according the use of clothing. 5) The at-home purchase intentions were higher in the order of at-home wear, casual wear and dress/suit. The higher the price and the more important the fit was, shopping at home was more difficult.