• Nuclear Engineering and Technology
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• v.47 no.6
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• pp.700-711
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• 2015

Sodium-cooled fast breeder reactors use liquid sodium as a moderator and coolant to transfer heat from the reactor core. The main hazard associated with sodium is its rapid reaction with water. Sodium-water reaction (SWR) takes place when water or vapor leak into the sodium side through a crack on a heat-transfer tube in a steam generator. If the SWR continues for some time, the SWR will damage the surface of the defective area, causing it to enlarge. This self-enlargement of the crack is called "self-wastage phenomena." A stepwise numerical evaluation model of the self-wastage phenomena was devised using a computational code of multicomponent multiphase flow involving a sodium-water chemical reaction: sodiumwater reaction analysis physics of interdisciplinary multiphase flow (SERAPHIM). The temperature of gas mixture and the concentration of NaOH at the surface of the tube wall are obtained by a numerical calculation using SERAPHIM. Averaged thermophysical properties are used to assess the local wastage depth at the tube surface. By reflecting the wastage depth to the computational grid, the self-wastage phenomena are evaluated. A two-dimensional benchmark analysis of an SWAT (Sodium-Water reAction Test rig) experiment is carried out to evaluate the feasibility of the numerical model. Numerical results show that the geometry and scale of enlarged cracks show good agreement with the experimental result. Enlarged cracks appear to taper inward to a significantly smaller opening on the inside of the tube wall. The enlarged outer diameter of the crack is 4.72 mm, which shows good agreement with the experimental data (4.96 mm).

• Nuclear Engineering and Technology
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• v.49 no.1
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• pp.1-5
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• 2017

The heavy water zero power reactor (HWZPR), which is a critical assembly with a maximum power of 100 W, can be used in different lattice pitches. The last change of core configuration was from a lattice pitch of 18-20 cm. Based on regulations, prior to the first operation of the reactor, a new core was simulated with MCNP (Monte Carlo N-Particle)-4C and WIMS (Winfrith Improved Multigroup Scheme)-CITATON codes. To investigate the criticality of this core, the effective multiplication factor ($K_{eff}$) versus heavy water level, and the critical water level were calculated. Then, for safety considerations, the reactivity worth of $D_2O$, the reactivity worth of safety and control rods, and temperature reactivity coefficients for the fuel and the moderator, were calculated. The results show that the relevant criteria in the safety analysis report were satisfied in the new core. Therefore, with the permission of the reactor safety committee, the first criticality operation was conducted, and important physical parameters were measured experimentally. The results were compared with the corresponding values in the original core.

• Journal of the Korean BIBLIA Society for library and Information Science
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• v.28 no.4
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• pp.341-362
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• 2017

This study is to analyze the applicability of new technologies to be applied to the foreseeable future's library. For this purpose, we measured the users' intention to accept the service by using the NFC based self-check out service as a new technology applicable to the library. Based on the Unified Theory of Acceptance Use of Technology (UTAUT), research models were derived, and the structural relationships between performance expectations, effort expectations, facilitation conditions, and perceived risks were analyzed. As a result of the analysis, perceived threats in the library did not affect the intention to use, and the performance expectation, effort expectation, and facilitation condition partially affected the intention to use. The gender of the moderator variable, there were some significant difference in promoting conditions.

• Human Ecology Research
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• v.56 no.5
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• pp.447-460
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• 2018

This study determines whether certain cognitive biases (i.e., time preference, goal attainment expectation, unrealistic optimism, and overconfidence) and a specific negative mood-state (i.e., anxiety) influence credit misuse among college students. Data were collected from fourth-year college students (N=1,146), all of whom attended the same university in the southwest United States. Hierarchical multiple regression analyses and moderator analyses were employed to test the research hypotheses. Results showed that specific cognitive biases and anxiety were directly associated with credit misuse. We found that the longer goal attainment was delayed, the greater the students' unrealistic optimism concerning future income; in addition, the more overconfident they became with respect to financial knowledge, the more frequently they engaged in credit misuse. The study also showed that the higher a student's level of anxiety, the more often that students engaged in credit misuse. We also found that cognitive bias factors and anxiety interact to influence credit misuse. Anxiety interacted with time preference and unrealistic optimism such that present-oriented time preference was negatively related to credit misuse while optimism toward future income was positively related to credit misuse, but only for students with high anxiety levels. The findings of this study are discussed in the context of understanding and preventing irresponsible financial behavior among young adults.

• Journal of the Korean Data and Information Science Society
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• v.23 no.3
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• pp.447-455
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• 2012

The purpose of this study is to examine the effect of reading development program on reading comprehension using meta-analysis method. The authors synthesized 70 studies regarding reading comprehension conducted during 2001 through 2011. The analyses revealed that 1) the average effect size of the reading development program yielded.763, which is regarded considerably large, 2) the effect size of elementary school group was the biggest, 1.030. There were statistically significant differences amongst school levels, 3) the average effect size of published journal articles was 1.250, which is statistically significantly larger than that of dissertation's.700, 4) regarding the methods to measure the effect of reading comprehension, the effect size of reading method was larger, and 5) the effect size of Korean reading development program was statistically larger than that of English reading development program. This study has limitation as it didn't include unpublished manuscripts, conference presentations, and the like, however this study is meaningful in terms that it tried to draw integrated conclusion about the effect of reading development programs using meta-analysis.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.12
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• pp.5550-5557
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• 2011

These days, the hospital management are paying more and more attention to the issue about the increasing employee's turnover ratio in hospital. Such issues are very important because the high turnover ratio reduce the productivity and morale of remaining workers, and means the unavoidable drainage of the accumulated know-how and technology of the hospital to the outsides. The result of such a negative development means the loss of competitive advantage compare to other hospitals. The purpose of this paper is to investigate how the management's leadership style influence on the job-satisfaction for the employees and the employee's turnover intension. At this time we will refer the effect of the hospital brand image as moderator. The result of this study could present the guide line to the hospital managers about the desirable leadership style to enhance the employee's productivity and also to reduce the turnover intention ratio.

• Analytical Science and Technology
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• v.16 no.1
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• pp.12-24
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• 2003

For the design and set-up of neutron induced prompt ${\gamma}$-ray spectroscopy system using $^{252}Cf$ neutron source, the effects of shielding and moderator materials have been examined. The $^{252}Cf$ source being used for TLD badge calibration in Korea Atomic Energy Research Institute was utilized for this preliminary experiment. The ${\gamma}$-ray background and prompt ${\gamma}$-ray spectrum of the sample containing Cl were measured using HPGe (GMX 60% relative efficiency) located at the inside of the system connected to notebook PC at the outside of the system (about 20 meter distance). The background activities of neutron and ${\gamma}$-rays were measured with neutron survey meter as well as ${\gamma}$-ray survey meters, respectively and the system was designed to minimize the activities. Prompt ${\gamma}$-ray spectrum was measured using ${\gamma}$-${\gamma}$ coincident system for reduce the background and the continuum spectrum. The optimum system was designed and set up using the experimental data obtained.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.10
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• pp.6102-6113
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• 2014

This is an empirical study of the factors impacting on supervisee's satisfaction on coaching and supervision in Korea. The study set four independent variables (supervisor, supervisee, contents, and organization), a moderator variable (relationship between the supervisor and supervisee) and a dependent variable (supervision satisfaction) based on the theoretical background on supervision. The data was collected from a survey of 112 certified coaches who had experienced supervision. As a results of the hypotheses tests, the supervisor and organization factors affected the supervision satisfaction. The relationship between the supervisor and supervisee moderates the impact of the supervisor and supervisee on the supervision satisfaction. They reported that the effectiveness of the coaching supervision in Korea was strongly dependent on the supervisors. These results were attributed to the short history of the coaching supervision and the lack of experience related to it. They also suggested that a great deal of research on coaching supervision will be needed to develop a clear identity/framework of coaching supervisor and its methods.

• Safety and Health at Work
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• v.9 no.1
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• pp.115-124
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• 2018

Background: Substantial empirical research has shown conflicting results regarding the influence of organizational external factors on construction risk management, suggesting the necessity to introduce a moderator into the study. The present research confirmed whether rules and regulations matter on the relationships between organizational external factors and construction risk management. Methods: Based on discouragement and organizational control theory, this research examined the effects of organizational external factors and rules and regulations on construction risk management among 238 employees operating in construction companies in Abuja and Lagos, Nigeria. A personally administered questionnaire was used to acquire the data. The data were analyzed using partial least squares structural equation modeling. Results: A significant positive relationship between organizational external factors and construction risk management was asserted. This study also found a significant positive relationship between rules and regulations and construction risk management. As anticipated, rules and regulations were found to moderate the relationship between organizational external factors and construction risk management, with a significant positive result. Similarly, a significant interaction effect was also found between rules and regulations and organizational external factors. Implications of the research from a Nigerian point of view have also been discussed. Conclusion: Political, economy, and technology factors helped the construction companies to reduce the chance of risk occurrence during the construction activities. Rules and regulations also helped to lessen the rate of accidents involving construction workers as well as the duration of the projects. Similarly, the influence of the organizational external factors with rules and regulations on construction risk management has proven that most of the construction companies that implement the aforementioned factors have the chance to deliver their projects within the stipulated time, cost, and qualities, which can be used as a yardstick to measure a good project.

• Nuclear Engineering and Technology
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• v.50 no.6
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• pp.989-995
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• 2018

Argonne National Laboratory of the United States and Kharkov Institute of Physics and Technology (KIPT) of Ukraine have cooperated on the development, design, and construction of a neutron source facility. The facility was constructed at Kharkov, Ukraine, and its commissioning process is underway. The facility will be used for researches, producing medical isotopes, and training young nuclear specialists. The neutron source facility is designed with a provision to include a cryogenically cooled moderator system-a cold neutron source (CNS). This CNS provides low-energy neutrons, which will be used in the scattering experiment and material structures analysis. Cold neutron guides, coated with reflective material for the low-energy neutrons, will be used to transport the cold neutrons to the experimental site. The cold neutron guides would keep the cold neutrons within certain energy and angular space concentrated inside, while most of the gamma rays and high-energy neutrons are not affected by the cold neutron guides. For the KIPT design, the cold neutron guides need to extend several meters outside the main shield of the facility, and curved guides will also be used to remove the gamma and high-energy neutron. The neutron guides should be installed inside a shield structure to ensure an acceptable biological dose in the facility hall. Heavy concrete is the selected shielding material because of its acceptable performance and cost. Shield design analysis was carried out for the CNS guide hall. MCNPX was used as the major computation tool for the design analysis, with neutron and gamma dose calculated separately. Weight windows variance reduction technique was also used in the shield design. The goal of the shield design is to keep the total radiation dose below the $5.0{\mu}Sv/hr$ guideline outside the shield boundary. After a series of iterative MCNPX calculations, the shield configuration and parameters of CNS guide hall were determined and presented in this article.