• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.8
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• pp.69-76
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• 2003

For stable combustion and safety of a structure of the propulsion system, a cooling system to the liquid rocket engine should be incorporated. In this study, Eulerian-Lagrangian scheme for two phase combustion, nongray radiation and soot formation effect, and film-wall interaction have been introduced to study the effect of film cooling. After briefly introducing the governing equation, combustion characteristics with change of wall temperature has been investigated by varying such parameters as fuel mass fraction for film cooling, diameter of the fuel droplet, overall mixture fraction of oxygen to fuel. Also, radiative heat flux is compared with the conductive one at the combustor wall.

• Journal of Fashion Business
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• v.21 no.3
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• pp.29-42
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• 2017

This study investigates the impact of female consumer self-image on pursued fashion style. A survey was carried out among 717 women between the ages of 20 and 60 living in Seoul, Incheon, and Gyeonggi. Analysis was conducted in the following manner: SPSS 18.0 was used to perform an Exploratory Factor Analysis (descriptive analysis, principal factor analysis, Pearson correlation analysis, frequency analysis, and reliability analysis) and AMOS 21.0 was used to carry out a Confirmatory Factor Analysis. Based on a Structure Equation Model, results show that ideal self-image and realistic self-image, which are factors derived from psychology, affect pursued fashion style. By contrast, social self-image - derived from social contexts - does not. Therefore, the female consumers' self-image influences pursued fashion style; this is opposed to the relationship between the realistic self-image and ideal self-image of women, which is more unconscious and self-satisfying. The presented results indicate that we should respond to changes in the fashion industry and develop a deeper understanding of consumer niches to discover the factors that predict purchasing behavior. This knowledge can then be applied to establish market strategies. This study contributes to the literature by producing preliminary data that can help support such strategy formulation in the fashion and clothing industry.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.31 no.1
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• pp.107-119
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• 1995

Turbulent flow characteristics and heat transfer in a three-dimensional room with a desk-type heat generating obstacle have been investigated numerically by the k-$\varepsilon$ two equation turbulence model. The room mole has one supply opening on the ceiling and two exhaust openings on the side walls. Th results of the flow structure and heat transfer have been represented for air for the inlet velocities in the range 0.1-10.0m/s. As the results of the three dimensional simulations, the relationships between mean Nusselt number and Reynolds number are clarified.

• The Journal of Asian Finance, Economics and Business
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• v.7 no.3
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• pp.303-310
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• 2020

The study aims to evaluate the factors affecting the intention to use digital banking in Vietnam. Multivariate data analysis techniques (Cronbach's Alpha test, Confirmatory Factor Analysis, Structure equation model) are used for the survey data collected from 201 customers who have access to digital banking. The analysis results show that: (1) attitude towards the service, perceived usefulness has a positive impacts on the intention to use; (2) convenience does not affect the intention to use digital banking services; (3) perceived usefulness factor has a positive effect on the attitude towards the service; (4) The perceived risk has a negative impact on attitude towards the service; (5) trust has no effect on the attitude towards the service; (6) ease of use has a positive impact on perceived usefulness; (7) trust has a positive effect on perceived risk. From the results of this study, perceived usefulness has a positive effect on attitude and intention to use the service. Therefore, it is necessary to enhance the sense of the usefulness of customers through media advertising and consulting so that customers fully understand the benefits brought about by using digital banking services. Perceived risk has a negative impact on attitude towards the service.

• Macromolecular Research
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• v.14 no.2
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• pp.155-165
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• 2006

The present article describes the experimental and theoretical observations on the formation of holographic, polymer-dispersed, liquid crystals and electrically switchable, photonic crystals. A phase diagram of the starting mixture of nematic liquid crystal and photo-reactive triacrylate monomer was established by means of differential scanning calorimetry (DSC) and cloud point measurement. Photolithographic patterns were imprinted on the starting mixture of LC/triacrylate via multi-beam interference. A similar study was extended to a dendrimer/photocurative mixture as well as to a single component system (tetra-acrylate). Theoretical modeling and numerical simulation were carried out based on the combination of Flory-Huggins free energy of mixing and Maier-Saupe free energy of nematic ordering. The combined free energy densities were incorporated into the time-dependent Ginzburg-Landau (Model C) equations coupled with the photopolymerization rate equation to elucidate the spatio-temporal structure growth. The 2-D photonic structures thus simulated were consistent with the experimental observations. Furthermore, 3-D simulation was performed to guide the fabrication of assorted photonic crystals under various beam-geometries. Electro-optical performance such as diffraction efficiency was evaluated during the pattern photopolymerization process and also as a function of driving voltage.

• Journal of the Korea Society of Computer and Information
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• v.21 no.10
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• pp.167-174
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• 2016

This study aims to reveal the influence of praise effects of elementary school students on their self-esteem and school adjustment resilience. First, it conducted theoretical study and reviewed the preceding studies and assumed that verbal and physical praise which are sub-factors of praise effects in elementary school students affected their self-esteem and school adjustment resilience. It was also assumed that there was a mediating effects of self-esteem between praise effect and school adjustment resilience of elementary school students. As a result of study on praise effects of elementary school students, it was found that verbal praise had an influence on their self-esteem and school adjustment resilience and physical praise affected their learning attitude. Self-esteem of elementary school students had an influence on their school adjustment resilience. Verbal praise of elementary school students had the greatest influence on their learning attitude. This study proposed policy suggestions of self-esteem and school adjustment resilience as an alternative based on the results of the study.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.05a
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• pp.311-314
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• 2009

A two-dimensional thermal response and ablation simulation code for predicting charring material ablation and shape change on solid rocket nozzle is presented. For closing the problem of thermal analysis, Arrhenius' equation and Zvyagin's ablation model are used. The moving boundary problem and endothermic reaction in thermal decomposition are solved by rezoning and effective specific heat method. For simulation of complicated thermal protection systems, this method is integrated with a three-dimensional finite-element thermal and structure analysis code through continuity of temperature and heat flux.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.05a
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• pp.315-319
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• 2009

Investigation of the lateral force fluctuations in an axisymmetric overexpanded compressed truncated perfect (CTP) nozzle for the shutdown transient is presented. These nozzles experience side-loads during start-up and shut-down operations, because of the flow separation at nozzle walls. Two types of flow separations such as free shock separation (FSS) and restricted shock separation (RSS) shock structure occur. A two-dimensional unsteady numerical simulation has been carried out over an axisymmetric CTP nozzle to simulate the lateral force fluctuations in nozzle during shutdown process. Reynolds Averaged Navier-Stokes equations are numerically solved using a fully implicit finite volume scheme. Governing equations are solved by coupled implicit scheme. Two equation k-$\omega$ SST turbulence model is selected. Unsteady pressure is measured at four locations along the nozzle wall. Present pressure variation compared well with the experimental data. During shutdown transient, separation pattern varies from FSS to RSS and finally returns to FSS. Several pressure peaks are observed during the RSS separation pattern. These pressure peaks generate lateral force or side loads in rocket nozzle.

• Journal of Mechanical Science and Technology
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• v.17 no.9
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• pp.1249-1260
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• 2003

This present work focuses on the influence of nonlinearities associated with impact on the rocking behavior of a rigid body block subjected to a two-dimensional excitation in the horizontal and vertical directions. The nonlinearities in rocking system are found to be strongly dependent on the impact between the block and the base that abruptly reduces the kinetic energy. In this study, the rocking systems of the two types are considered : The first is an undamped rocking system model that disregards the energy dissipation during the impact and the second is a damped rocking system, which incorporates energy dissipation during the impact. The response analysis is carried out by a numerical method using a non-dimensional rocking equation in which the variations in the excitation levels are considered. Chaos responses are observed over a wide range of parameter values, and particularly in the case of large vertical displacements, the chaotic characteristics are observed in the time histories, Poincare sections, the power spectral density and the largest Lyapunov exponents of the rocking responses. Complex behavior characteristics of rocking responses are illustrated by the Poincare sections.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.33 no.7
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• pp.552-558
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• 2009

An experimental study using the combustor with branch tube was conducted in order to model the industry combustor with FGR (flue gas recirculation) system and to study a thermo-acoustic instability generated by a branch tube. The branch tube is a structure used to modify a system geometry and then to change its pressure field, and the thermo-acoustic instability, usually occurs in a confined geometry, can result in serious problems on industrial combustors. Thus understanding of the instability created by modifying geometry of combustor is necessary to design and operate combustor with FGR system. Pressure fluctuation in the combustion chamber was observed according to diameter and length of branch and it was compared with the solution of 1-D wave equation. It was found that branch tube affects the pressure field in the combustion chamber, and the pressure fluctuation in the combustion chamber was reduced to almost zero when phase difference between an incipient wave in the combustion chamber and a reflected wave in the branch tube is $\pi$ at the branch point. Also, the reduction of pressure fluctuation is irrespective of the installed height of branch tube if it is below $h^*=0.9$ in the close-open tube and open-open tube.