• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.6 no.3
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• pp.58-64
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• 1997

A micromechanics model to describe the elastic behavior of fiber or whisker reinforced metal matrix composites was developed and the stress concentrations between reinforcements were investigated using the modified shear lag model with the comparison of finite element analysis (FEA). The rationale is based on the replacement of the matrix between fiber ends with the fictitious fiber to maintain the compatibility of displacement and traction. It was found that the new model gives a good agreement with FEA results in the small fiber aspect ratio regime as well as that in the large fiber aspect ratio regime. By the calculation of the present model, stress concentration factor in the matrix and the composite elastic modulus were predicted accurately. Some important factors affecting stress concentrations, such as fiber volume fraction, fiber aspect ratio, end gap size, and modulus ratio, were also discussed.

• International Commerce and Information Review
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• v.12 no.4
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• pp.279-302
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• 2010

A better selection model on management innovative enterprises is needed since the Korean government provides multi benefits to those selected enterprises. However, the selection model's propriety is suspicious because of the shortage of consideration of assessment items. In particular, the most important two assessment items, strategy and performance are suspected of multicollinearity because of high correlation scores. No consideration on multicollinearity among those items leads to erroneous selection which doubly counts the same components with different item names. The principle component analysis is applied to factor out the uncorrelated items. Using the resulted principle components, the new estimations are carried out. The comparison between estimated results from using principle components and non principle components shows that the present selection model overly considers the performance items compared to the real effect of items, which is a result of multicollinearity between performance and strategy.

• Journal of the Korea Institute of Military Science and Technology
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• v.14 no.2
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• pp.321-325
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• 2011

After investigating the analytic model to predict penetration depth, we propose an analytical model which can be used in estimating the normal penetration characteristics of small projectiles, when they are impacted to the concrete targets with ordnance velocities. The major parameters of this model are nose factor of penetrator, compressive strength and density of targets, and impact velocity. We can predict accelerations, velocities, displacements of projectiles and applied forces by this proposed model. Estimated penetration depths were shown 5% error. We also verified the usefulness of the new method with laboratory impact test data.

• Journal of information and communication convergence engineering
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• v.7 no.3
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• pp.361-365
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• 2009

This paper has been presented the transport characteristics of FinFET using the analytical potential model based on the Poisson's equation in subthreshold and threshold region. The threshold voltage is the most important factor of device design since threshold voltage decides ON/OFF of transistor. We have investigated the variations of threshold voltage and drain induced barrier lowing according to the variation of geometry such as the length, width and thickness of channel. The analytical potential model derived from the three dimensional Poisson's equation has been used since the channel electrostatics under threshold and subthreshold region is governed by the Poisson's equation. The appropriate boundary conditions for source/drain and gates has been also used to solve analytically the three dimensional Poisson's equation. Since the model is validated by comparing with the three dimensional numerical simulation, the subthreshold current is derived from this potential model. The threshold voltage is obtained from calculating the front gate bias when the drain current is $10^{-6}A$.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.5
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• pp.508-513
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• 2009

Friction is an important factor for precise position tracking control of servo systems. Servo systems with highly nonlinear friction are sensitive to the variation of operating condition. To overcome this problem, we use the LuGre friction model which can consider dynamic characteristics of friction. The LuGre friction model is used as a feed-forward compensator to improve tracking performance of servo systems. The parameters of the LuGre friction model are identified through experiments. The experimental result shows that the tracking performance of servo systems with higherly nonlinear friction can be improved by using feed-forward friction compensation.

• Journal of Power Electronics
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• v.9 no.2
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• pp.275-287
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• 2009

This paper investigates analytical models of Conduction and Switching Losses (CASLs) of a matrix-Z-source converter (MZC). Two analytical models of the CASLs are obtained through the examination of operating principles for a Z-source inverter and ac-dc matrix converter respectively. Based on the two models, the analytical model of CASLs for a MZC is constructed and visualized over a range of exemplified operating- points, each of which is defined by the combination of power factor (pt) and modulation index (M). The model provides a measurable way to approximate the total losses of the MZC.

• Journal of the Korea Institute of Building Construction
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• v.8 no.4
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• pp.61-69
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• 2008

The size of the construction projects become huge and complex, and the depth of excavation for the underground structures become deeper. Also the working area is not enough for loading materials and temporary facilities. This is the most case of recent construction projects in downtown area. Top-down is the most useful method for this kind of construction projects. Top-down construction method consists of supporting method, retaining wall type, foundation type and construction direction such as up-down or up-up. construction managers have to select sub-elements for top-down construction method in planning phase. This study is to suggest the sub-elements selection model for the top-down construction method, and the case study is conducted for evaluating this model.

• 유체기계공업학회:학술대회논문집
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• 2005.12a
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• pp.742-747
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• 2005

A model, which can analyze the hydrological performance for small hydropower(SHP) plants having no flow duration characteristics has been studied and developed. System performance of existing SHP plant under operating was analyzed by using the developed model. The annual operational rate of SHP plant showed that the data were in good agreement with predicted results from the model. Based on these results, several SHP sites to be exploited were selected and the performance characteristics were analyzed by using the developed model. Also, primary design values such as design flow rate, plant capacity, and operational rate were suggested. As a result, it was found that the methodology used in this study is useful tool to predict the hydrological system performances of SHP sites.

• Journal of the Korean Society of Clothing and Textiles
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• v.25 no.7
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• pp.1215-1226
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• 2001

The purpose of this study is to develop a model of adolescent's conspicuous consumption on clothes. For this study, questionnaires were administered to 400 adolescents in Kwang-Ju. Employing a sample of 283, data were analyzed by using the structural equation model of the Lisrel analysis, in addition to cronbach's alpha coefficient for reliability and confirmatory factor analysis for validity. The results of this study was found that a conceptual model for adolescent's conspicuous consumption on clothes was judged to provide acceptable goodness of fit. Specifically, materialism and clothing conformity had a direct effect on conspicuous consumption on clothes, and materialism, hedonic shopping orientation and clothing interests had a indirect effect on conspicuous consumption on clothes. The results indicated that clothing conformity had important influence on conspicuous consumption and its influence on adolescent's conspicuous consumption was mediated by materialism, hedonic shipping orientation and clothing interests.

• The Journal of Asian Finance, Economics and Business
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• v.3 no.2
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• pp.67-76
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• 2016

The paper explores determinants of corporate adoption of social media and the role of technology acceptance model in the path. This paper assimilates some components of the technology acceptance dimension and social expectation theories to determine corporate intentions to use social media. Six hundred and forty-eight samples collected from hotel staff in Korea are analyzed using factor analysis, structural equation model techniques and one-way analysis of variance. The results show that corporate needs, social expectations, ease of use and usefulness should be viewed as important antecedents explaining the firm's behavioral intention to use social media. The study also finds that the ease of use and usefulness of the technology acceptance model have positive directional mediation effects in the path diagram.