• Nuclear Engineering and Technology
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• v.49 no.1
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• pp.124-133
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• 2017

In-vessel retention by passive external reactor vessel cooling under severe accident conditions is a viable approach for retention of radioactive core melt within the reactor vessel. In this study, a new and versatile coating technique known as "cold spray" that can readily be applied to operating and advanced reactors was developed to form a microporous coating on the outer surface of a simulated reactor lower head. Quenching experiments were performed under simulated in-vessel retention by passive external reactor vessel cooling conditions using test vessels with and without cold spray coatings. Quantitative measurements show that for all angular locations on the vessel outer surface, the local critical heat flux (CHF) values for the coated vessel were consistently higher than the corresponding CHF values for the bare vessel. However, it was also observed for both coated and uncoated surfaces that the local rate of boiling and local CHF limit vary appreciably along the outer surface of the test vessel. Nonetheless, results of this intriguing study clearly show that the use of cold spray coatings could enhance the local CHF limit for downward-facing boiling by > 88%.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.11 no.6
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• pp.749-757
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• 1999

Holographic interferornetric tomography can provide reconstruction of instantaneous three dimensional gross flow fields. The technique however confronts ill-posed reconstruction problems in practical applications. Experimental data are usually limited in projection and angular scanning when a field is captured instantaneously or under the obstruction of test models and test section enclosures. An algorithm, based on a series expansion method, has been developed to improve the reconstruction under the ill-posed conditions. A three-dimensional natural convection flow around two interacting isothermal cubes is experimentally investigated. The flow can provide a challenging reconstruction problem and lend itself to accurate numerical solution for comparison. The refractive index fields at two horizontal sections of the thermal plume with and without an opaque object are reconstructed at a limited view angle of 80" The experimental reconstructions are then compared with those from numerical calculation and thermocouple thermometry. It confirms that the technique is applicable to reconstruction of reasonably complex, three-dimensional flow fields.elds.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2017.11a
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• pp.24-25
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• 2017

Gamma-C₂S (γ-C₂S) is a substance that is difficult to react with water under normal temperature but can absorb a large amount of CO₂ in the air. The addition of γ-C₂S to cementitious materials through the curing of CO₂ can improve the pore structure and improve the durability of the material. In this study, three kind of Ca-bearing materials : CaO, Ca(OH)₂, CaCO₃, were calcined 2.5h at 1450℃ to synthesize γ-C₂S after mixing with SiO₂ respectively. Among them, Ca(OH)₂ mixed with SiO₂ after calcining shows highest content. Synthesized γ-C₂S was added to the cement mortar, after water curing for 1 month, accelerated carbonation test was experimented. After 28d accelerated carbonation test, pore structure will be detectived by MIP. Based on the MIP result, following the calculation method of Fractal theory, the pore structure will be quantitative described.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.29 no.1
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• pp.17-22
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• 2016

The activation energy of a material is an important factor that significantly affects the lifetime and can be used to develop a degradation model. In this study, a thermal analysis was carried out to evaluate and collect quantitative data on the degradation of insulation materials like EPR and CSP used for nuclear power plant cables. The activation energy was determined from the relationship between log ${\beta}$ and 1/T based on the Flynn.Wall.Ozawa method, by a TGA test. The activation energy was also derived from the relationship between ln(t) and 1/T based on isothermal analysis, by an OIT test. The activation energy of EPR derived from thermal analysis was used to calculate the accelerated aging time corresponding to the number of years of use, employing the Arrhenius equation, and determine the elongation corresponding to the accelerated aging time.

• 한국IT서비스학회:학술대회논문집
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• 2003.11a
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• pp.713-721
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• 2003

The time to market and productivity of embedded system needs a quality measurement process management of embedded software. But, defect management without preemptive analysis or prediction is not useful for quality measurement process management. This subject is focused on the defect that is one of the most important attributes of software measure in the process. Defining of defect attribute and quality measurement process management is according to understanding of embedded sw characteristics and defect data. So, this study contributes to propose the good method of the quantitative based on defect management in the test phase of sw lifecycle.

• Korean Journal of Occupational Health Nursing
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• v.28 no.4
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• pp.242-252
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• 2019

Purpose: This study aimed to identify factors influencing depressive symptoms in public and private sector employees. Methods: Survey data on 23,602 workers who had worked in the public or private sector were obtained from the 2014 Korean Working Condition Survey (KWCS). Symptoms of depression were measured using the WHO-5 Well-being Index. Data were analyzed using a $x^2$ test, t-test, and multivariate stepwise logistic regression to determine the factors affecting the symptoms of depression. Results: First, the prevalence of depressive symptoms was 41.1 % in public sector employees and 43.4 % in private sector employees. Second, the factors commonly affecting depressive symptoms in public and private sector employees were residence area, cognitive demands, development opportunities, social support from colleagues, social support from supervisors, social community at work, job rewards, and work-family conflict. In addition, age, company size, atypical work, ergonomic risks, quantitative demands, emotional demands, influence, and job insecurity were found to be predictors of depressive symptoms unique to private sector employees. Conclusion: Mental health programs including the employee assistance program (EAP) should be developed and implemented after considering the risk factors affecting depressive symptoms.

• The Journal of Korean Physical Therapy
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• v.33 no.5
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• pp.258-263
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• 2021

Purpose: Myofascial syndrome is a chronic muscle pain caused by repetitive motions with stress-related muscle tension. This study aimed to investigate the validity and reliability of the evidence for diagnosing myofascial pain syndrome in trapezius muscle using a pressure algometer and surface electromyography. Methods: The experiments were performed using a total of 10 subjects, and the target locations were determined by means of a pressure algometer in the right upper trapezius muscle. The part with the lowest pain value as the trigger point and the part with the highest pain value as the non-pain trigger point were selected for measuring the locations. The median frequency and average frequency were measured in those locations with electromyography. To check the muscle fatigue, the upper trapezius muscle was moved up and down for 2 seconds at 5-second intervals in 30 seconds. The measured values were evaluated using the independent paired t-test and MannWhitney U-test. Results: The median frequency at the non-trigger point (13.7) was significantly higher than that at the trigger point (7.3). Furthermore, the mean frequency (14.7) at the non-trigger point was significantly higher than that at the trigger point (6.3). Conclusion: The results showed the correlations between the trigger points of the muscle pain and frequency analysis of surface electromyography. Thus, this study may be possible to use as a diagnostic tool for myofascial pain syndrome.

• Journal of Engineering Education Research
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• v.22 no.3
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• pp.18-31
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• 2019

In addition to technical skills and competencies, communication competence has been identified to be important to engineering students who will be drivers of innovation in a rapidly changing society. Drawing on the previous studies, this research examines the results of an empirical exploration of engineering students' perception of speaking ability and their communicative competence. To date, there has been most of the research conducted on 'writing' (e.g., its educational process, class designs, ability, etc.) for engineering students. However, relatively little attention has been paid to engineering students' speaking ability perception and their competence diagnosis. This study relies on quantitative data obtained from one survey questionnaire and one test conducted respectively. The sample consists of 386 engineering students as well as 481 non-engineering students for the 1st survey. And to measure communicative competence, 150 engineering students as well as 136 non-engineering students participated in the test. Our findings show that firstly, there were significant differences in perception of speaking ability by majors and gender. Whereas there was no difference in the same survey by grade. Secondly, there was a close and significant relationship between sub-factors of speaking ability. Thirdly, there were significant differences in communicative competence by majors. Whereas there was no difference by gender and grade. Fourthly, there was a close and significant relationship between sub-factors of communicative competence. These findings are expected to provide an explanation for the improvement on engineering students' speaking ability and to encourage the participation in extra-curricular activities and programs in engineering school.

• Health Communication
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• v.13 no.2
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• pp.175-183
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• 2018

Purpose: The purpose of this study was to compare communication competence, nursing professionalism, work environment and job satisfaction between outpatient nurses and ward nurses, and to identify the correlation among variables. Methods: The participants were 90 outpatient nurses and 98 ward nurses at the two general hospitals. Data were collected using self-administered questionnaires. Data were analyzed using descriptive statistics, ${\chi}^2-test$, independent t-test and Pearson's correlation coefficient. Results: There were statistically significant differences between two groups in nursing professionalism, possibilities for development, commitment to the workplace, social support from colleagues, social community at work and job satisfaction, outpatient nurses showed higher level than ward nurses except commitment to the workplace. The work environment variables and nurses' job satisfaction were mostly correlated. Job satisfaction showed significant negatively correlated with quantitative demands, emotional demands and role conflicts in both groups nurses. Conclusion: These findings showed that nursing work environments were the most important factor for job satisfaction of both group nurses. Therefore, it is necessary to put efforts in improving nursing work environment and to develop diverse strategies for human resource management.

• The Journal of Asian Finance, Economics and Business
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• v.8 no.5
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• pp.697-706
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• 2021

This quantitative study aims to examine the effect of family ownership on company performance empirically. Specifically, this study examines the moderating effect of corporate governance on the relationship between family ownership and company performance which has never been explored in the previous studies. This study's main target population was all listed companies in the Indonesian Capital Market Directory (ICMD) for 2008-2018. The study used criteria, namely data completeness, to measure research variables and obtained 2996 data or firm-year observations. The research contingency model to test the proposed hypothesis was the General Moment Method (GMM). The study presents the results of data descriptions shows the average, median, maximum, minimum, and standard deviation values for each variable. The descriptive data shows that family ownership is common in Indonesia: 64% of 244 companies in the sample. The inferential analysis results using a multiple regression model test show that family ownership significantly reduces company performance. However, corporate governance proxied by the board of directors, managerial risk profile, and independent commissioners significantly moderate the relationship between family ownership and company performance. Besides, the managerial risk profile and independent commissioners strengthened while the board of commissioners' presence weakened the effect of family ownership on performance.