• Structural Engineering and Mechanics
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• v.70 no.1
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• pp.33-41
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• 2019

The influence of two parameters on fatigue damage predictions of a variably loaded cantilever beam has been examined. The first parameter is the geometry of the cantilever beam and the weld connecting it to a rear panel. Variables of the geometry examined here include the cantilever length, the weld width on the critical cross-section and the angle of the critical cross-section. The second parameter is the safety factor, as set out by the Eurocode 3 standard. An analytical approach has been used to calculate the stresses at the critical cross-section and standard rainflow counting has been used for the extraction of the load cycles from the load history. The results here suggest that a change in the width and angle of the critical cross-section has a non-linear impact on the fatigue damage. The results also show that the angle of the critical cross-section has the biggest influence on the fatigue damage and can cause the weld to withstand fatigue better. The second parameter, the safety factor, is shown to have a significant effect on the fatigue damage calculation, whereby a slight increase in the endurance safety factor can cause the calculated fatigue damage to increase considerably.

• Journal of the Korean Mathematical Society
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• v.51 no.1
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• pp.55-65
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• 2014

A graph G is called a fractional (g, f, n)-critical graph if any n vertices are removed from G, then the resulting graph admits a fractional (g, f)-factor. In this paper, we determine the new toughness condition for fractional (g, f, n)-critical graphs. It is proved that G is fractional (g, f, n)-critical if $t(G){\geq}\frac{b^2-1+bn}{a}$. This bound is sharp in some sense. Furthermore, the best toughness condition for fractional (a, b, n)-critical graphs is given.

• Journal of Korean Academy of Nursing
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• v.48 no.3
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• pp.323-334
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• 2018

Purpose: The purpose of this study was to develop a scale to measure person-centered critical care nursing and verify its reliability and validity. Methods: A total of 38 preliminary items on person-centered critical care nursing were selected using content validity analysis of and expert opinion on 72 candidate items derived through literature review and qualitative interviews. We conducted a questionnaire survey with 477 nurses who worked in intensive care units. The collected data were analyzed using exploratory factor analysis (EFA) and confirmative factor analysis (CFA) with SPSS and AMOS 24.0 program. Results: EFA was performed with principal axis factor analysis and Varimax rotation. The 15 items in 4 factors that accounted for 50.8% of the total variance were identified by deleting the items that were not meet the condition that the commonality should be .30 or more and the factor loading over .40. We named the factors as compassion, individuality, respect, and comfort, respectively. The correlation coefficient between this scale and the Caring Perception Scale was r=.57 (p<.001), which determined concurrent validity. The item-total correlation values ranged from .39 to .63, and the internal consistency for the scale was Cronbach's ${\alpha}=.84$. Conclusion: The reliability and validity of the 15 item person-centered critical care nursing scale were verified. It is expected that the use of this scale would expand person-centered care in critical care nursing.

• International Journal of Concrete Structures and Materials
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• v.18 no.3E
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• pp.191-198
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• 2006

The objective of this study is to examine fracture characteristics of concrete at early ages, i.g. critical stress intensity factor, critical crack-tip opening displacement, fracture energy, and bilinear softening curve based on the concepts of effective-elastic crack model and cohesive crack model. A wedge splitting test for Mode I was performed on cubic wedge specimens with a notch at the edge. By experimenting with various strengths and ages, load-crack mouth opening curves were obtained, and the results were analyzed by linear elastic fracture mechanics and FEM(finite element method). The results from the test and analysis showed that critical stress intensity factor and facture energy increased while critical crack-tip opening displacement decreased with concrete aging from 1 day to 28 days. Four parameters of bilinear softening curve from 1 day to 28 days were obtained from a numerical analysis. The obtained fracture parameters and bilinear softening curves at early ages from this study are to be used as a fracture criterion and an input data for the finite element analysis of concrete at early ages.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2011.11a
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• pp.15-16
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• 2011

Construction automation and robotics are being taken notice as an alternative to improve productivity and quality. Reflecting on these purpose, automation system, called RCA(Robotic-crane based Construction Automation) system, is developed and have been verified through a pilot project recently in Korea. To apply the RCA system in high-rise building effectively, each management factors of element technologies in the system is derived and assessed critical factor. The purpose of this study, management factors of element techniques, consisted of RCA system, is classified through questionnaires/interviews targeting system developers and construction managers in pilot project site, and critical factors is selected using AHP.

• Nuclear Engineering and Technology
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• v.50 no.7
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• pp.1138-1147
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• 2018

Delayed hydride cracking (DHC) is an important failure mechanism for Zircaloy tubes in the demanding environment of nuclear reactors. The threshold stress intensity factor, $K_{IH}$, and critical hydride length, $l_C$, are important parameters to evaluate DHC. Theoretical models of them are developed for Zircaloy tubes undergoing non-homogenous temperature loading, with new stress distributions ahead of the crack tip and thermal stresses involved. A new stress distribution in the plastic zone ahead of the crack tip is proposed according to the fracture mechanics theory of second-order estimate of plastic zone size. The developed models with fewer fitting parameters are validated with the experimental results for $K_{IH}$ and $l_C$. The research results for radial cracking cases indicate that a better agreement for $K_{IH}$ can be achieved; the negative axial thermal stresses can lessen $K_{IH}$ and enlarge the critical hydride length, so its effect should be considered in the safety evaluation and constraint design for fuel rods; the critical hydride length $l_C$ changes slightly in a certain range of stress intensity factors, which interprets the phenomenon that the DHC velocity varies slowly in the steady crack growth stage. Besides, the sensitivity analysis of model parameters demonstrates that an increase in yield strength of zircaloy will result in a decrease in the critical hydride length $l_C$, and $K_{IH}$ will firstly decrease and then have a trend to increase with the yield strength of Zircaloy; higher fracture strength of hydrided zircaloy will lead to very high values of threshold stress intensity factor and critical hydride length at higher temperatures, which might be the main mechanism of crack arrest for some Zircaloy materials.

• International Commerce and Information Review
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• v.8 no.3
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• pp.71-95
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• 2006

In recent, T-commerce is widely dispersed as alternative type of commerce. It is forecasted that t-commerce system is used more than e-commerce system. Therefore more and more t-commerce-related industries are also recognizing that t-commerce is a critical business model. It is needed to understand the concept of t-commerce and develop the t-commerce marketing strategy. CEO analyses consumer's behaviors according to the data about buyers and applies the advantage of t-commerce to the communication with customers. This t-commerce system plays an important role in maximizing customer satisfaction and affecting their intention to reuse it. Therefore this paper attempts to identify T-commerce critical success factors and divide between use-intention group and unuse-intention group by taking out a discriminant function by the discriminant analysis. This lays a foundation in developing T-commerce strategy. According to the discriminant function extracted, convenience factor, amusement factor, system quality factor, product perception factor are significant in the sequence of influential degree. However, usefulness factor and speedy connection factor are not significant. In result, the target hitting rate is 77.9% in the first unuse-intention group and it is 95.2% in the second use-intention group. The total discriminant target hitting rate is computed to higher value, 86.55%. The statistic package, SPSS 12.0, is used to survey and analyse data and test the hypothesis. The validity and reliability of variables are verified by both reliability analysis and factor analysis. The discriminant analysis is used to tell the difference between use-intention group and unuse-intention group.

• Proceedings of the KIEE Conference
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• 2001.07b
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• pp.1126-1128
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• 2001

A single-stage high-power-factor electron ic ballast operating in critical conduction mode is presented in this paper. The proposed topology is based on integration of a boost-like converter and a LCC Type half-bridge serial resonant inverter. The power-factor-correction(PFC) stage is a boost-like converter operating in critical conduction mode for positive and negative half cycle voltage respectively at line frequency (60Hz) so that a high power factor is achieved naturally. The simulated and experimental results for 100w fluorescent lamps operating at 42kHz switching frequency and 220V line voltage have been obtained.

• International Journal of Advanced Culture Technology
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• v.6 no.1
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• pp.23-31
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• 2018

The purpose of this study was to identify mediating effect of major satisfaction in the effect of critical thinking disposition on disaster recognition. For this study, 237 students of nursing students from universities in Jeollanam do participated in the study. The data collection was collected on Dec 1 to 7, 2017. The descriptive statistics was used to analyze general characteristics of participants, the differences in disaster recognition according to general characteristics were analyzed by t-test or ANOVA. Regression analysis was conducted to confirm the effect of critical thinking disposition on disaster recognition and Baron, R.M. And Kenny, D.A.'s mediation effect statistic analysis was used to confirm the mediating effect of major satisfaction in critical thinking disposition on disaster recognition. As a result, the critical thinking disposition affects the disaster recognition, and it was judged that the major satisfaction was mediating role. intellectual fairness sub-factor showed perfect mediating effect and confidence and general truth sub-factor showed partial mediating effect. Based on the above findings, it can be seen that not only critical thinking but also satisfaction with the major should be considered in order to increase the recognition of the sudden disaster. In this case, research for linking critical thinking disposition and major satisfaction is likely to be meaningful. Through the results of this study, we suggest the program development of a linkage between critical thinking disposition and major satisfaction to increase the recognition of disaster.

• Geomechanics and Engineering
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• v.1 no.1
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• pp.85-96
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• 2009

The radius and coordinate of sliding circle are taken as searching variables in slope stability analysis. Genetic algorithm is applied for searching for critical factor of safety. In order to search for critical factor of safety in slope stability analysis efficiently and in a robust manner, some improvements for simple genetic algorithm are proposed. Taking the advantages of efficiency of neighbor-search of the simulated annealing and the robustness of genetic algorithm, a hybrid optimization method is presented. The numerical computation shows that the procedure can determine the minimal factor of safety and be applied to slopes with any geometry, layering, pore pressure and external load distribution. The comparisons demonstrate that the genetic algorithm provides a same solution when compared with elasto-plastic finite element program.