• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.40 no.8
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• pp.647-654
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• 2012

Supercooled large droplet issues in aircraft icing have been continually reported due to the important safety considerations. In order to simulate the impingement behavior of large droplets, a two-dimensional and compressible Navier-Stokes code was developed to determine the flow field around the test model. Also, the Eulerian-based droplet impingement model including a semi-empirical approach for the droplet-wall interaction process and droplet break-up was developed. In particular, the droplet-wall interactions were considered as numerical boundary conditions for the droplet impingement simulation in the supercooled large droplet conditions. Finally, the present results were compared with the experimental test data and the LEWICE results. The droplet impingement area and maximum collection efficiency values between present results and wind tunnel data were in good agreements. Otherwise, the inclination of collection efficiency of the present result is over-predicted than the wind tunnel data around a lower surface of the NACA 23012 airfoil.

• Journal of Korean Society of Transportation
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• v.27 no.4
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• pp.127-135
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• 2009

Most traffic information that drivers receive while driving are stored in their short-term memory and disappear within a few seconds. Contemporary modeling approaches using a dummy variable can't fully explain this phenomenon. As such, this study proposes to use utility functions of real-time in-vehicle traffic safety information (IVTSI), analyzing its safety impacts based on empirical data from an on-site driving experiment at signalized intersection approach with a limited visibility. For this, a driving stability evaluation model is developed based on driver's driving speed choice, applying an ordered probit model. To estimate the specified utility functions, the model simultaneously accounts for various factors, such as traffic operation, geometry, road environment, and driver's characteristics. The results show three significant facts. First, a normal density function (exponential function) is appropriate to explain the utility of IVTSI proposed under study over time. Second, the IVTSI remains in driver's short-term memory for up to nearly 22 second after provision, decreasing over time. Three, IVTSI provision appears more important than the geometry factor but less than the traffic operation factor.

• Transactions of the Korean Society of Automotive Engineers
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• v.9 no.2
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• pp.107-115
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• 2001

It is required more precise analysis for practical load because of complexities and varieties of vehicle structure. To establish the numerical model, many researchers have been developed designing tools for linking F.E. Analysis results and experimental results. There studies have generally focused on each experimental method or analytical method separately. There are few studies based on both methods. This paper conceives new procedure for the determination of the load direction and magnitude applied on mechanical structures. New procedure is the combination of the analytical and empirical method with analyzed strain by F.E. Analysis under unit load and with measured principal stress by strain gages under driving load, respectively. In this paper, we theorize the procedure of practical load determination and make the validity and the practicality of the procedure with the application to T-shape jointed structure. F.E. Analysis is conducted to get the principal stress on arbitrary points in the F.E. model of T-shape joint under unit load. Then experiment is carried out to get the principal stress on the same points of F.E. model. To demonstrate the actual driving condition, the load conditions are bending and torsion. From these two data sets, the magnitude, the direction and the position of load can be obtained. Theory and practice do not always coincide; since there are some errors such as ill-poseness, measuring error and modeling error in experimental data, we examine the proper method of error minimization.

• The Journal of Engineering Geology
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• v.16 no.3 s.49
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• pp.227-233
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• 2006

Bedrock is inhomogeneous for its genetically diverse origins and geological conditions when it forms, and especially, conglomerates and core-stones are one of these typical composite geo-materials composed of weak matrixes and strong pebbles. Mechanical properties of these composite bedrocks, like a conglomerate, generally vary depending on the mechanical properties and distributions of pebbles and the matrix. Therefore, regarding the consequence of understanding mechanical property of bedrocks in the designing slopes, tunnels, and other engineering facilities, empirical rock classification methods generally applied in the mechanical property modeling may not be suitable and rather, we may need some other classification methods, or tests more specific for these inhomogeneous composite bedrocks. This study includes a series of analyses to see elastic behaviors and modulus of composite geo-materials using homogenization theory. Forty nine case models were made for the elastic analysis with considering 5 factors such as gravel content, gravel size, strength of matrix, sorting and dip angle. The results analyzed are applicable to calculate elastic modulus of composite geo-materials as conglomerates and core-stones.

• Journal of Digital Convergence
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• v.14 no.2
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• pp.83-98
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• 2016

This study attempted to test not only the influence of transformational leadership(TFL) on employees' unethical pro-organizational behavior(UPB), but also the mediating effect of organizational identification(OID) between TFL and employees' UPB. This study employed two research methods: literature review and empirical testing of the developed hypotheses. Data were collected through online questionnaire instruments from 229 employees working at companies in Korea. To test the hypotheses, structural equation modeling was employed. The model is shown as adequately fitting to the data. The results showed that there was not a positive and statistically significant relationship between TFL and employees' UPB, and OID played as a mediator in the relationship between TFL and employees' UPB. These findings provide a meaningful implication that the positive impact of TFL is linked to employees' UPB through OID.

• The Journal of the Korea Contents Association
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• v.12 no.2
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• pp.398-410
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• 2012

This study aims to investigate the effect of perceived supervisor support(PSS) on employees' in-role and extra-role performance by examining the mediating role of job-based psychological ownership(JBPO). Data were collected from 269 employees from a variety of companies. Both regression analysis and structural equation modeling were used. Previous research has found a positive relationship between PSS and job performance. However, empirical analysis has not yet demonstrated PSS-performance relationships mediated through JBPO. Thus, this study investigated this mediation in predicting in-role and extra-role performance. In the current study, JBPO was found to fully mediate the relationship between PSS and in-role performance and to partially mediate the relationship between PSS and extra-role performance. Future discussions and practical implications are discussed.

• Journal of Distribution Science
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• v.15 no.3
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• pp.49-60
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• 2017

Purpose - The aims of this study are follows. We investigated to find out how country image and brand image affect the consumer perceived value, consumer attitude, and purchase intention of foreign infant foods in China. Especially, we focused on investigate for the moderating role of consumer knowledge between national image, brand image and consumer perceived value of foreign infant foods in China. Research design, data, and methodology - This study analyzed the effect of national image and brand image on purchase intention through consumer perceived value and consumer attitude. This study collected data for empirical analysis of Chinese consumers who have been purchase experience infant foods in China. 256 copies of questionnaire data were used for substantial analysis. Before testing the hypothesis, factor analysis was conducted to test the construct validity of measurement items. Hypotheses about effects between variables were verified using structural equation modeling analysis and hierarchical regression analysis. Results - First, the country image had a positive effect on consumer perceived value of foreign infant foods. Second, the brand image had a positive effect on consumer perceived value of foreign infant foods. Third, the consumer perceived value had a positive effect on consumer attitude. Fourth, the consumer attitude had a positive effect on purchase intention. Fifth, the consumer knowledge was moderating roles between brand image and consumer perceived value of foreign infant foods. However, the consumer knowledge did not effect of moderating between country image and perceived value of consumers. Conclusions - First, the impact of country image and brand image on consumer perceived value of foreign infant foods in China can be seen as a universal psychology of consumers who trust pure foreign products such as high quality, technology, etc. Second, consumer perceived value of foreign infant foods has a positive effect on consumer attitude, and this attitude is leading to purchase intention. Third, the consumer knowledge between brand image and perceived value acts as a moderating variable. It means that the consumer's knowledge can shape the perception of the brand image more strongly.

• Journal of The Korean Astronomical Society
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• v.49 no.5
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• pp.193-198
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• 2016

Early-type galaxies (ETGs) are supposed to follow the virial relation $M=k_e{\sigma}^2R_e/G$, with M being the mass, σ_* being the stellar velocity dispersion, R_e being the effective radius, G being Newton's constant, and k_e being the virial factor, a geometry factor of order unity. Applying this relation to (a) the ATLAS^3D sample of Cappellari et al. (2013) and (b) the sample of Saglia et al. (2016) gives ensemble-averaged factors 〈k_e〉 = 5.15 ± 0.09 and 〈k_e〉 = 4.01 ± 0.18, respectively, with the difference arising from different definitions of effective velocity dispersions. The two datasets reveal a statistically significant tilt of the empirical relation relative to the theoretical virial relation such that $M{\propto}({\sigma}^2_*R_e)^{0.92}$. This tilt disappears when replacing R_e with the semi-major axis of the projected half-light ellipse, a. All best-fit scaling relations show zero intrinsic scatter, implying that the mass plane of ETGs is fully determined by the virial relation. Whenever a comparison is possible, my results are consistent with, and confirm, the results by Cappellari et al. (2013). The difference between the relations using either a or R_e arises from a known lack of highly elliptical high-mass galaxies; this leads to a scaling (1 - ϵ ) ∝ M^0.12, with ϵ being the ellipticity and $R_e=a\sqrt[]{1-{\epsilon}}$. Accordingly, a, not R_e, is the correct proxy for the scale radius of ETGs. By geometry, this implies that early-type galaxies are axisymmetric and oblate in general, in agreement with published results from modeling based on kinematics and light distributions.

• Journal of Digital Convergence
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• v.15 no.9
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• pp.155-165
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• 2017

The purpose of this study is to identify the direct effects of PSM on job satisfaction (JS) and perceived job performance (PJP) in public institutions and to identify indirect effects of the mediator. In particular, we define the person-organization fit (POF) used as the mediator as the fitness of the personnel system and identify the influence of POF in the relationship between PSM, JS, and PJP. The questionnaires used in this study were conducted for the members of Changwon Public Health Center and empirical analysis using structural equation modeling was conducted and the following results were obtained. First, PSM in the integrated public service organization has a positive effect on JS and PJP. Second, PSM shows that JS and PJP of organization members are improved through mediating effect of POF. It can be concluded that PSM can improve JS and PJP through institutional fit between members and organizations.

• The Journal of the Korea Contents Association
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• v.10 no.1
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• pp.353-364
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• 2010

The purpose of this study is to examine the effect of leader-member exchange(LMX) on employee's affective commitment and continuance commitment focusing on the mediating role of job stress. On the basis of theoretical linkages between the constructs, a conceptual model and hypotheses were established. The sample included 482 employees. Structural equation modeling(SEM) was employed to test the hypothesized relationships in the conceptual model. This study shows that the proposed model is reasonably fit to the actual data. Empirical results indicate that LMX has a negative impact on employee's job stress, has a positive impact on employees' affective commitment and continuance commitment. Employees' job stress has partially mediated effect on the relationship between LMX and employees' affective commitment, but has not mediated effect on the relationship between LMX and employees' continuance commitment.