• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.11
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• pp.1391-1397
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• 2012

A cam ring gear (CRG) system based on a hypotrochoid curve consists of a pinion with roller teeth and its conjugated internal CRG. In this study, we investigated contact forces, contact stresses, and load stress factors to predict the surface pitting life using an exact CRG profile by introducing the profile modification coefficient. The results show that the pitting life can be extended significantly by increasing the profile modification coefficient without any other change of parameters in the CRG system.

• 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.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.35 no.4
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• pp.372-376
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• 2022

Since the ZnO varistor is a semiconductor device, the internal thermal distribution during the varistor operation is recognized as an important factor in the performance and deterioration of the varistor. For an optimal varistor structure design, the thermal runaway phenomenon during the varistor operation was interpreted using the Comsol 5.2 analysis program by a finite element analysis. The maximum temperature of the center measured in the cross section of the ZnO varistor was confirmed to increase as the temperature moved from the lower electrode to the center towards the upper electrode up to 572.6 K. The electrodes are thinned so that the influence of the Schottky barrier is not great. The heat gradient balance is determined to be improved when the electrode of the hybrid form is introduced. The thickness, density, pore distribution, impurity uniformity, and particle size of the ZnO varistor are required, and it is determined that the pyrolysis gradient will be improved regardless of the electrode thickness. When these results are applied to design the ZnO varistor, the optimal structure of the ZnO varistor can be obtained.

• Journal of the Korea Society of Computer and Information
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• v.14 no.2
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• pp.59-68
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• 2009

This paper aims to explore the factors of learner's flow and to develop and validate a scale to measure the flow in Massive Multiplayer Online Role Playing Game(MMORPG) for education. First of all, potential factors were drawn through literature review. The potential stage comprises 6 factors(learner's psychological characteristics, learner's skill, importance of game, environment for learner, instructional design, and instructional environment) and 16 subfactors. With total 48 items developed. a survey was carried out among 293 elementary learners who had been participating in a commercial MMORPG for English skills to measure their flow in the MMORPG by utilizing the potential scale. Using the responses collected from 288 respondents, exploratory factor analysis, reliability analysis, and confirmatory factor analysis were performed. The expository factor analysis showed that items within each sub-factors could be bound into one factor. That is, the variables evaluating learner's flow were divided into six factors(learner's psychological characteristics, learner's skill, importance of game, environment for learner, instructional design, and instructional environment). And these factors were interpreted consisting of 16 sub-ones. Reliability estimates indicated that the evaluation tool had good internal consistency. The confirmatory factor analysis did confirm the model suggested by the expository factor analysis. Over fit measures(CFI, NFI, NNFI) showed the good suitability of the model. Findings of this study confirmed the validity and reliability of the scale to measure learner's flow in MMORPG.

• Journal of Distribution Science
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• v.12 no.3
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• pp.105-109
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• 2014

Purpose - Leadership style is an important factor in determining the attitude and behavior of employees and their satisfaction with an organization. Contributing the efficiency of an organization, Especially, servant leadership focusing on meeting employees' hopes and desires positively affect success of the organization and performance of employees. In the airline service industry it is necessary to conduct studies for an internal marketing on servant leadership that emphasizes the trust in the dignity of humans and spirit of service to subordinates as a factor affecting the job satisfaction. Research design, data, and methodology -Therefore, in this research, it is empirically analyzed that employees' perception of a supervisor's support plays mediating role in the relationship between employees' perception of servant leadership and perception of an organization's support using multiple and hierarchal regression analysis targeting 243 employees working in D Airline. Result - As a result, Employees' employees' perceived supervisor's support mediates the relationship between employees' perceived servant leadership of a supervisor and employees' perceived organizational support. Conclusions - This study suggests that the servant leadership of a supervisor perceived by employees constitutes an important preceding variable in enhancing the employees' perception on organizational support.

• The Journal of Information Systems
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• v.26 no.3
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• pp.25-46
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• 2017

Purpose The purpose of this study is to analyze the factors for continuous use intention of the simple payment service based on FinTech for Chinese residents in Korea. The Technology Acceptance Model(TAM) and the continuous use model of information system were applied to the AliPay service, which is the most used by Chinese people. Design/methodology/approach In this study, internal factors and external factors for the simple payment service were derived through previous studies and the effects of the users' perspectives on the intention of continuous use were analyzed. As a result, convenience, responsiveness, perceived usefulness, and suitability were supported as factors affecting ongoing intention to use simple payment service. Especially, convenience is a factor affecting the duration of the simple payment service and it is an important factor for the continuous use of the service. Findings As the number of foreigners living or working in Korea is increasing, understanding the perception of the simple payment service and analyzing the factors for the continuous use can be meaningful as a basic research for the market advancement and growth of domestic FinTech companies is.

• Journal of the Society of Naval Architects of Korea
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• v.53 no.5
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• pp.435-446
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• 2016

In this study, hydrodynamic and mooring analysis for LNG FSRU moored by an internal turret with 9 mooring lines are numerically performed using commercial softwares, Hydrostar and Ariane. Met-ocean combinations for screening method are taken from wave governed condition(BV Rule Note NR 493) with relative heading between wave and wind between −45° and +45° and relative heading between wind and current between −30° and +30°. Extreme mooring analysis and sensitivity analysis are performed for intact and damaged (=one line missing) conditions and the parameters for sensitivity analysis are wave peak period, peak enhancement factor and line pretension. In the viewpoint of the design tension in mooring line, chain diameter is designed to satisfy safety factor for each conditions. As the chain diameter is increased from 152mm to 171mm, the designtension is reduced while the minimum breaking load is increased.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.29 no.1
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• pp.57-66
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• 2019

Drones, which are used in various fields, are vulnerable to various security threats such as physical deodorization attacks and information leakage attacks because they operate in an unmanned environment and use wireless communication with weak security. In particular, research is needed to prevent damages such as leakage of stored information and unauthorized use due to illegal drone deodorization. In this paper, we propose a context - aware drone control mechanism that protects stored internal information and prevents unauthorized use when the drones are illegally deactivated. We also demonstrated the feasibility of the proposed mechanism as a prototype implementation and experiment.

• The Journal of Industrial Distribution & Business
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• v.14 no.12
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• pp.1-9
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• 2023

Purpose: As China's economic development enters new normal, employee happiness degree of small and micro enterprises will take on new features. The purpose of this paper is to discover the characteristics of changes in employee happiness, and provide reference and management suggestions. Research design, data and methodology: This paper determined the factors affecting employee happiness, established a measure model of happiness, measured and analyzed employee happiness by selecting more than 1,108 employees from 30 domestic small and micro enterprises. Results: First, the overall level of happiness in small and micro enterprises is relatively low. Second, there is no significant difference in happiness perception among employees in terms of the six factors. Third, the employees of small and micro enterprises have the highest happiness in three issues, including work distribution, internal interpersonal relationships, and less institutional constraints, the happiness on the two compensation benefits and a democratic management issue is the lowest. Fourth, gender factor has no significant effect on employee happiness, while age, working years, education, position, and the nature of employment have a significant impact on happiness. Conclusions: Employee happiness of small and micro enterprises will take on new features. Some human resource management suggestions are proposed from different perspectives based on the survey results.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.22 no.1
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• pp.138-144
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• 2013

The automation technology for overlay welding is needed due to the occurrence of severe corrosion and abrasion on the surface of internal contact in different shape of fittings. In Korea, different shapes of fittings have been manufactured by using the imported equipment of overlay welding automation at some companies. Thus the research on the development of overlay welding automation system (in short, OWAS) for a large L-type tube is urgently needed. In this paper, the investigation is focused on the optimal design of a supporting base for the (currently developing) OWAS of large L-type tube. Specifically we assume that the base which supports the equipment during the process of overlay welding is loaded as self-weight in the direction of gravity through static analysis especially when it is rotated 180 degree on the OWAS. For optimal design of a supporting base for OWAS of large L-type tube, Solidworks(R) (for 3-dimensional modelling) and ANASYS Workbench(R) (for structural analysis) are incorporated so as to proceed an optimization routines based on Response Surface Method (RSM) and Design of Experiment (DOE). In more specific, DOE finds out major factors (or dimensions) of the supporting base by using MINITAB(R). Then the regression equations between design variables (the major factors of supporting base) and response variables (deformation, stress and safety factor for the supporting base), which will be resulted in by RSM, verify the major factors of DOE. In the next step, Central Composite Design (CCD) plans 20 simulations of ANASYS Workbench(R) and then figures out the optimal values of design variables which will be reflected on the manufacturing of supporting base. Finally welding experiment is conducted to figure out the influence of overlay welding quality in applying the optimized design values of supporting base to the actual OWAS.