• Transactions of the Korean Society of Automotive Engineers
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• v.17 no.1
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• pp.80-86
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• 2009

Main bearing cap is one of the essential structural elements in internal combustion engine. Main bearing cap guides and holds the crankshaft, withstanding the full combustion and inertia loads of the engine. A seamless design methodology using FEA has been proposed to produce a reliable design of main bearing cap. A Levy's thick cylinder model was applied to calculate the contact pressure between bearing shell and housing bore. A calculated contact pressure at housing bore is within the allowed limit comparing with that from bearing shell model. An adequate FEA model was suggested to obtain reliable solutions for the durability of main bearing cap. 3D global model consists of engine bulkhead, main bearing cap, and bolts. Sub-model consisting of cap and part of bolts is used to get detailed solution of main bearing cap. A very careful contact modeling practice is needed to resolve the convergence problems frequently encountering during combined geometric and material non-linear problems. A proposed methodology has been applied to the main bearing cap model successfully and obtained reliable stress results and fatigue safety factors.

• Korea Journal of Hospital Management
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• v.11 no.4
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• pp.37-62
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• 2006

This study investigates the antecedents of knowledge sharing behavior focusing on the individual level factors in an assumption that the behavior is initiated from the individual level decisions. A hypothesis that the relation between personality trait and behavior is mediated by the social-cognitive constructs contained in the Theory of Planned Behavior(TPB) is tested. For the study, we suggest a TPB extended model that extends original TPB model by including conscientiousness facet of FFM(Five Factor Model). This study uses a cross-sectional design. Data were collected from a self-reported survey on 197 nurses in a tertiary hospital. The results showes a significant positive relationship between the conscientiousness facet of FFM and knowledge sharing behavior. In the TPB extended model, the conscientiousness facet has significant direct effects on all the constructs of original TPB model. Of the TPB exogenous constructs, the social norm construct alone has a significant effect on intention and the perceived behavioral has a direct significant effect on the knowledge sharing behavior. These results confirm the importance of conscientiousness in predicting knowledge sharing behavior and clarify the characteristics of knowledge sharing behavior as a contextual, job oriented behavior in a workplace. We conclude that personality trait as conceptualized in the FFM needs to be integrated into TPB model in explaining the knowledge sharing behavior. Based on these results theoretical and practical implications are discussed.

• Journal of Navigation and Port Research
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• v.34 no.2
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• pp.145-152
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• 2010

The management of safety at sea is based on a set of internationally accepted regulations and codes, governing or guiding the design and operation of ships. The regulations most directly concerned with human safety and protection of the environment are, in general, agreed internationally through the International Maritime Organization(IMO). IMO has continuously dealt with safety problems and, recognized that the human element is a key factor in both safety and pollution prevention issues(IMO, 2010). This paper proposes a human error analysis methodology which is based on the human error taxonomy and theories (SHELL model, GEMS model and etc.) that were discussed in the IMO guidelines for the investigation of human factors in marine casualties and incidents. In this paper, a cognitive process model, a human error analysis technique and a marine accident causal chains focused on human factors are discussed, and towing vessel collision accidents are analyzed as a case study in order to examine the applicability of the human error analysis technique to marine accidents. Also human errors related to those towing vessel collision accidents and their underlying factors are discussed in detail.

• Bulletin of the Korean Chemical Society
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• v.29 no.3
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• pp.555-561
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• 2008

In air stripping of ammonia from the aqueous solution, a new removal model was presented considering the equilibrium principles for the ammonia in aqueous solution and between the aqueous and air phase. The effects of pH, temperature and airflow rate on the ammonia removal were evaluated with the model. In addition, the saturation degree of ammonia in air was defined and used to evaluate the effect of each experimental factor on the removal rate. As pH (8.9 to 11.9) or temperature (20 to 50 oC) was increased, the overall removal rate constants in all cases were appeared to be increased. Our presented model shows that the degrees of saturation were about the same (0.45) in all cases when the airflow condition remains the same. This result indicates that the effect of pH and temperature were directly taken into consideration in the model equation. As the airflow increases, the overall removal rate constants were increased in all cases as expected. However, the saturation degree was exponentially decreased with increasing the airflow rate in the air phase (or above-surface) aeration. In the subsurface aeration the saturation degree remains a constant value of 0.65 even though the airflow rate was increased. These results indicate that the degree of saturation is affected mainly by the turbulence of the aqueous solution and remains the same above a certain airflow rate.

• Nuclear Engineering and Technology
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• v.33 no.4
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• pp.409-422
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• 2001

The dynamic character of a system of the governing differential equations for the one- dimensional two-fluid model, where the momentum flux parameters are employed to consider the velocity and void fraction distribution in a flow channel, is investigated. In response to a perturbation in the form of a＇traveling wave, a linear stability analysis is peformed for the governing differential equations. The expression for the growth factor as a function of wave number and various flow parameters is analytically derived. It provides the necessary and sufficient conditions for the stability of the one-dimensional two-fluid model in terms of momentum flux parameters. It is demonstrated that the one-dimensional two-fluid model employing the physical momentum flux parameters for the whole range of dispersed flow regime, which are determined from the simplified velocity and void fraction profiles constructed from the available experimental data and $C_{o}$ correlation, is stable to the linear perturbations in all wave-lengths. As the basic form of the governing differential equations for the conventional one-dimensional two-fluid model is mathematically ill posed, it is suggested that the velocity and void distributions should be properly accounted for in the one-dimensional two-fluid model by use of momentum flux parameters.s.

• Water for future
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• v.23 no.4
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• pp.499-507
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• 1990

Real-time reservoir operation models during flood period require optimization of hourly releases from the input data through on-line system. And predicted values. An algorithm of the simulation model to resolve the problem has already been reported with formulation of objectives to minimize the flood damage in downstream reaches and to conserve water at the end of operation for the later use. This paper presents an application of the model to a single reservoir system at the Daecheong Dam during flood and the results are reviewed. This paper also reviews measured inflows and releases in the past. The model is applied to the flood hydrographs of several return periods assuming different reservoir levels at the beginning of the operation. Also it demonstrates the simulation of test run with inflow forecasts obtained by rainfall-runoff model and compares the results. As a result, the model can use efficiently the flood control capacity with consideration of risk factor for the uncertainties associated with inflow forecasts.

• Journal of Korean Academy of Nursing
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• v.38 no.6
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• pp.779-788
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• 2008

Purpose: This study was designed to construct a structural model explaining depression in university students. Methods: Data were collected from 1,640 university students by questionnaire, and analyzed using AMOS 5.0 to test the hypothetical model. Results: Fitness statistics for the modified model were GFI=.93, AGFI=.89, NFI=.91, and RMSEA=.081. All the 12 paths in the modified model proved to be statistically significant. Depression of university students accounted for 52% of the covariance by the factors. The factor that had the most influence on depression was individual vulnerability, and followed by sequence order, stress, social support, coping, and self-efficacy. Depression was influenced directly by individual vulnerability, stress, social support, and coping, and indirectly by individual vulnerability, stress, social support, and self-efficacy. Conclusion: A screening and management system for the high risk group is needed to effectively prevent depression and reduce rate of depression in university students. Detailed support programs which specifically deal with prevailing stressors should be developed to effectively reduce the harmful effects of individual vulnerability and stress. It is anticipated that the model constructed in this study could be utilized as a reference in developing various strategies to prevent and intervene depression in university students.

• Fashion & Textile Research Journal
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• v.13 no.3
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• pp.390-397
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• 2011

This study investigates the influences of shopping enjoyment and risk reduction on customers' attitude and the behavioral intention in the Internet shopping mall using a moving virtual model. For this study, we produced a moving virtual model to present a fashion product. The virtual model walks for about one minute on the stage. After respondents viewed it, they completed a questionnaire. The questionnaire consists of online shopping enjoyment, risk reduction, customers' attitude and behavioral intention. Respondents are limited to females aged in their 20s and 30s, who have experienced Internet shopping and are highly interested in fashion products. 411 samples were used for the final analysis. Cronbach's alpha, factor analysis, and multiple regression analysis were conducted. The results are as follows. Online shopping enjoyment and risk reduction influenced the behavioral intention directly as well as through the attitude. However, the size of the influence indicated that online shopping enjoyment is larger than risk reduction. Therefore, Internet malls should utilize the moving virtual model to provide customers with enjoyment and risk reduction, which will increase customers' favorable attitudes and the behavioral intention such as purchase intention and word of mouth.

• Journal of the Korea Society for Simulation
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• v.13 no.1
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• pp.41-50
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• 2004

The purpose of this paper is to analyse the manager's policy to maximize the profit in a multiple-server queueing facility with a limited queue capacity. We assume that the level of advertizing effects on the arrival rate of customers to the facility. The model without ‘word of mouth effect’ is assumed that the arrival rate is independent on the qualify of service level. We estimate the service quality by the balking rate of customers from system. We extend this to the model with ‘word of mouth effect’. To achieve the maximum profit, the most important factor is the considerably high utilization of facility for both models. Given service rate, we should maintain an effective arrival rate to some extent. To this end, among the available options, an increase of advertizing effort is more desirable than reducing the fee if the service value of customers remains unchanged. We also investigate whether the variability of service time has a significant impact on determining the optimal policy. The cost of service variability is not so expensive as that in a single server model due to the reduced variability of service times in a multiple-server model.

• Journal of Applied Reliability
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• v.17 no.2
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• pp.168-180
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• 2017

Purpose: In this research, we develop an effectiveness analysis simulation model using Agent Based Modeling with Communication Effects for the development of a new weapon system. Methods: To describe the future battlefield that has more complexity, we develop Agent Based Modeling to describe communication Effects. We use the communication theory (Path-Loss Model) and the real map. Results: We have compared simulation model with real map and simulation model without real map. The Blue Survival Ratio of simulation model with real map is worse than one without real map since the performance of communication gets lower. Conclusion: There are many studies about the effectiveness analysis of a weapon system. Most of previous researches assumed no communication error. In the real world, however, it's not appropriate assumption. Therefore, this study considers the communication error and shows that it is important factor in the effectiveness analysis.