• Journal of the Korean Society of Safety
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• v.29 no.6
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• pp.166-171
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• 2014

Nuclear power plants are equipped with the reactor trip system (RTS) and the engineered safety features actuation system (ESFAS) to improve safety on the normal operation. In the event of the design basis accident (DBA), a various of post accident monitor(PAM)systems support to provide important details (e.g. Containment pressure, temperature and pressure of reactor cooling system and core exit temperature) to determine action of main control room (MCR). Operator should be immediately activated for the accident mitigation with the information. Especially, core exit temperature is a critical parameter because the operating mode converts from normal mode to emergency mode when the temperature of core exit reaches $649^{\circ}C$. In this study, uncertainty which was caused by exterior environment, characteristic of thermocouple/connector and accuracy of calibrator/indicator was evaluated in accordance with ANSI-ISA 67.04. The square root of the sum of square (SRSS) methodology for combining uncertainty terms that are random and independent was used in the synthesis. Every uncertainty that may exist in the hardware which is used to measure the core exit temperature was conservatively applied and the associative relation between the elements of uncertainty was considered simultaneously. As a result of uncertainty evaluation, the channel statistical allowance (CSA) of single channel of core exit temperature was +1.042%Span. The range of uncertainty, -0.35%Span ($-4.05^{\circ}C$) ~ +2.08%Span($24.25^{\circ}C$), was obtained as the operating criteria of core exit temperature.

• Transactions of the Korean Society of Mechanical Engineers
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• v.9 no.6
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• pp.750-756
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• 1985

Experimental investigation was carried out to study the natural convection of water and silicon oil due to end temperature differences in a horizontally insulated rectangular enclosure of aspect ratio 0.1 with a special attention on the core configuration in the laminar boundary-layer flow regime. Rayleigh number ranges covered herein are Ra=4.40 * 10$^{6}$ -9.64 * 10$^{7}$ for water and Ra=1.69*10$^{5}$ -3.80*10$^{6}$ for silicon oil, respectively. In the case of water, for Ra.geq.2.21 * 10$^{7}$ there appeared distinct horizontal thermal layers adjacent to the horizontal boundaries in the core and the temperature distribution outside the horizontal thermal layers, i.e., in the mid-core region, is vertically stratified. The core flow pattern was shown to be nonparallel with a weak back flow in the mid-core for Ra.geq.3.63 *10$^{7}$ . In the case of silicon oil, distinct horizontal thermal layers appeared along the core horizontal boundaries for Ra.geq.1.27 * 10$^{6}$ with a stratified temperature distribution in the mid-core, but the core flow pattern in this case was shown to be parallel. In addition, secondary flow appeared near the hot wall for Ra.geq.3.80 * 10$^{6}$ . Nusselt number, Nu, was found to be proportional to R $a^{0.3}$ for water and R $a^{0.28}$ for silicon oil in the boundary-layer flow regime. There also in an indication from the comparison with other results that Nu is independent of aspect ratio for water in the boundary-layer flow regime in low aspect ratio enclosures.res.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.198-203
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• 2008

In the present study, the deformation behavior of both of metal and polymer combination on impact was investigated. They have showed a different deformation behavior when the co-axially combined projectile was impacted on rigid target. The theory according to Taylor's simplified approach assumes an ideally rigid-plastic material model exhibiting rate-independent behavior and simple one-dimensional wave propagation concepts that neglect radial inertia. In the case of impact with polymeric materials, elastic strain in general are not negligible compared with plastic strain; and the rigid-plastic material behavior assumed by Taylor for metallic materials cannot be applied any more. Since, the sleeve and the core materials have widely different mechanical properties, they will produce a significant difference of mechanical impedance with each other. Therefore these impedance mismatch influences on the deformation behavior sleeved polymer projectile on impact. As a result, sleeved projectiles will generate a very interesting impact behavior. Therefore, the according to sleeved metal material and core polymer material can see expected. The objective of this study was to investigate the factors which influences on deformation behavior pattern of sleeve materials surface.

• Journal of Korea Society of Industrial Information Systems
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• v.11 no.3
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• pp.82-89
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• 2006

Optical transmission system related to network infra of ubiquitous is a essential bridge technique between metro network and access point. So, it is need to develop this technique. In this paper, we develop 1Gbps SNMP optical transmitter/receiver system based on 1 core ring-type WDM PON. The developed system can reduce number of optic fiber and doesn't need extra transmitter/receiver. Also, this system can extend nodes owing to many node per wavelength, acts rapidly against security cutting, and acts independent of protocols.

• The Journal of Information Systems
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• v.18 no.4
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• pp.1-18
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• 2009

Technology transfer has emerged as one of me important key issues for obtaining competitive advantage. To improve the chances of effective technology transfer, a strategic alliance between partners have to mirror respective objectives. The purpose of this study is to analyze the influence of core competences on organizational performance in domestic companies, including the moderating effect of technology transfer. This study adopted research variables such as technology competence, resource competence, marketing competence as independent variables, with organizational performance as a dependent variable, including the moderating variable of technology transfer. 113 companies data were collected from me survey. The result of this empirical study is summarized as follows. First, marketing, resource, and technology competence are the important determinants to influence organizational performance in direct effect model. Second, only marketing competence has positive influence to organizational performance in organizations with higher needs of technology transfer. Third, technology transfer as a moderating variable moderates me effect of the core competences on organizational performance.

• Korean Journal of Optics and Photonics
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• v.15 no.1
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• pp.12-16
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• 2004

We show that the extinction ratio is improved using slight asymmetry in two core refractive indices of polarization independent very short vertical directional couplers with the double-sided deep-ridge (DSDR) waveguide structure. The optimum asymmetry with the maximum extinction ratio and the tolerance of the refractive index of core with the extinction ratio larger 1ha]1 30 ㏈ increase as the thickness of inner cladding layer and the two cores decrease due to the increase of the coupling strength between the two cores. Also, the device length and the tolerance of the device length with the extinction ratio larger than 30 ㏈ decrease as the thickness of the inner cladding layer and the two cores decrease due to the increase of the coupling strength between the two cores. We show that polarization independent vertical directional couplers with the DSDR waveguide structure with the device length less than 100 ${\mu}{\textrm}{m}$ and the extinction ratio larger than 30 ㏈ could be implemented.

• The Journal of Korean Academic Society of Nursing Education
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• v.24 no.3
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• pp.279-289
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• 2018

Purpose: The study is to confirm the influence of self-efficacy, critical thinking disposition, self-leadership, and communication competency on the core competencies of the preceptor. Methods: Data were collected from August 27 to September 7, 2017 using structured questionnaires for 127 preceptors at a general hospital located in Korea. SPSS/Win 23.0 was used to analyze the frequency, percentage, mean, standard deviation, independent t-test, one-way ANOVA, Pearson's correlation coefficients, and stepwise multiple regression. Results: The mean score of the core competencies of the preceptors was $3.94{\pm}0.35$ (range 1-5); self-efficacy was $3.88{\pm}0.49$; critical thinking disposition was $3.54{\pm}0.36$; self-leadership was $3.66{\pm}0.39$; communication competency was $3.71{\pm}0.35$. There were no statistically significant differences between the core competencies of the preceptor and general characteristics. The core competencies of the preceptors were significantly correlated with self-efficacy (r=.61, p<.001), critical thinking disposition (r=.69, p<.001), self-leadership (r=.59, p<.001), and communication competency (r=.58, p<.001). The core competencies of the preceptors were affected by critical thinking disposition (${\beta}=.54$, p<.001), followed by communication competency (${\beta}=.24$, p<.001). The explanatory power by the factors was 51% (F=63.66, p<.001). Conclusion: The results suggest that critical thinking disposition and communication competency are important predictors of the core competencies of the preceptors.

• Journal of The Korean Society of Integrative Medicine
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• v.10 no.4
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• pp.93-102
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• 2022

Purpose : The purpose of this study was to analyze the change in thickness of transvers abdominis, internal oblique, and external oblique when virtual reality based ring fit adventure is applied to young adults in order to investigate the effect of ring fit adventure on core stabilization. Methods : 30 subjects participated in the experiment. Subjects were randomly assigned to two groups. 15 subjects performed ring fit adventure core exercise (experimental group) and 15 subjects bridge and dead bug exercise (control group). The ring fit adventure core exercise program consists of 6 types, 1) bow pull, 2) overhead lunge twist, 3) pendulum bend, 4) seated ring raise, 5) plank, 6) warrior III pose. Each exercise was performed for 5 minutes, for a total of 30 minutes. The bridege and dead bug exercise were performed for 15 minutes each for a total of 30 minutes. All interventions were performed 3 times a week for 4 weeks. Thickness of the abdominal muscles was measured with a ultrasound. The paired t-test was used to compare the thickness of the transverse abdominis, internal oblique, and external oblique before and after intervention, and the comparison between groups was analyzed using the independent t-test. Results : As a result, in the experimental group, thickness of transverse abdominis and internal oblique increased significantly (p<.05), but external oblique decreased significantly (p<.05), and in the control group, thickness of transverse abdominis, internal oblique, and external oblique increased significantly (p<.05). There was a significant difference in external oblique in the difference between groups (p<.05). Conclusion : These study results showed that core exercise using ring fit adventure can reduce external oblique and increased selective muscle activity of transverse abdominis and internal oblique of the deep abdominal muscles, so it is meaningful as an effective intervention for core stabilization.

• Journal of Engineering Education Research
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• v.27 no.2
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• pp.35-50
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• 2024

The purpose of this study is to identify the core competencies of graduate students at A research university in the context of graduate education in science and engineering, and to develop and validate a diagnostic tool to measure them. To achieve the research objectives, first, 6 factors and 18 sub-competencies of core competencies were derived based on a review of domestic and foreign studies, cases of excellent research-centered overseas universities, and interviews with members of A University. Second, a theoretical model was constructed by deriving behavioral indicators based on the core competencies and sub-competencies, and a preliminary survey was conducted on 188 graduate students of University A to verify the statistical validity of the theoretical model. Results of exploratory and confirmatory factor analysis, the core competencies of graduate students at A research university consisted of 6 factors, 16 sub-competencies, and 77 items. Specifically, it included "Independent research capability(13 items)", "Social Entrepreneurship(10 items)", "Academic agility(15 items)", "Ingenious Challenges(15 items)", "Collegial Collaboration(9 items)", and "Mueunjae leadership(15 items)". This study contributes to the development of theories related to core competencies of graduate students in science and engineering, and has practical significance as a basis for a data-driven competency-based graduate education system.

• Journal of the Earthquake Engineering Society of Korea
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• v.19 no.6
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• pp.273-282
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• 2015

In this study, shaking table test has been carried out for the dual frame passive control system for seismic performance verification of the proposed system. The proposed system was separated into two independent frameworks that are strength resistant core and frame structure by connecting to the damper. Moreover, the seismic performance improvement of the proposed system has been verified by comparing and analyzing the experimental results of the proposed system with an existing core system. As a result of the shaking table test, acceleration and displacement responses of dual-frame vibration control system are decreased than those of the existing strength resistant type core system. In the case of the core system, while the damage was concentrated on the column of first floor, the damage of the dual system was dispersed in each layer. The damage also was concentrated on the damper, almost no damage occurs to the structural members. It has been emphasized that installed dampers in the proposed dual system reduce the input energy of whole structure by absorbing seismic input energy, which leads overall system damage to be reduced.