• 한국연소학회:학술대회논문집
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• 한국연소학회 1999년도 제19회 KOSCO SYMPOSIUM 논문집
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• pp.71-79
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• 1999

Numerical analysis on the characteristics of nitrogen oxides (NOx) formation in turbulent nonpremixed hydrogen-air flames was carried out. Lagrange IEM model and Assumed PDF model were applied to consider turbulence-chemistry interaction known to affect the production of NOx. Partial equilibrium assumption was used to predict nonequilibrium effect to which one-half power dependence between EINOx normalized by flame residence time and global strain rate is attributed. As a result. such one-half power dependence could be reproduced only by reaction model including $HO_{2}$and $H_{2}O_{2}$, which means its dependence on Damkohler number; nonequilibrium effect. This dependence was shown better in the region of higher global strain. Besides, the improvement of turbulence model is required to predict mean flow properties quantitatively in the radial direction.

• Transactions of the Korean Society of Mechanical Engineers A
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• 제30권7호
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• pp.809-815
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• 2006

The temperature and loading-rate dependence on the mechanical behavior of single-walled carbon nanotubes under axial compression and torsion is examined with classical molecular dynamics simulation. The critical buckling is found to depend on the temperature and loading-rate. The yielding under torsion is also found to depend on the temperature and loading-rate. But it is shown that the compression and torsional stiffness are independent of the varied temperatures and loading-rates.

• Journal of Institute of Control, Robotics and Systems
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• 제20권8호
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• pp.849-853
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• 2014

In micro-scale electromechanical systems, the power to perform accurate position sensing often greatly exceeds the power needed to generate motion. This paper explores the implications of sampling rate and amplifier noise density selection on the performance of a system identification algorithm using a capacitive sensing circuit. Specific performance objectives are to minimize or limit convergence rate and power consumption to identify the dynamics of a rotary micro-stage. A rearrangement of the conventional recursive least-squares identification algorithm is performed to make operating cost an explicit function of sensor design parameters. It is observed that there is a strong dependence of convergence rate and error on the sampling rate, while energy dependence is driven by error that may be tolerated in the final identified parameters.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2002년도 International Meeting on Information Display
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• pp.674-677
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• 2002

Vertically aligned CNTs were grown on Fe-deposited $SiO_2$ substrates using thermal CVD of acetylene gas. The size of Fe particle is controlled by the flow rate of $NH_3$ and pretreatment time, which leads to control the diameter of CNTs. As the diameter of CNTs decreases, the growth rate is enhanced with an inverse dependence of the CNT diameter. The growth rate of CNTs increases linearly as the growth time increases until 30 min but is rapidly decreased over 40 min. We found an inverse relation between the diameter and growth rate of carbon nanotubes. As the diameter of CNTs increases, the compartment layers of bamboo-shaped CNTs appear more frequently. A base-growth model is suitable to explain the dependence of growth rate and structure of CNTs on the diameter size of catalytic particles.

• Journal of the Korean institute of surface engineering
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• 제48권3호
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• pp.126-130
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• 2015

A high-pressure depletion method using plasma chemical vapor deposition (CVD) is often used to deposit hydrogenated microcrystalline silicon (${\mu}c-Si:H$) films of a low defect density at a high deposition rate. To understand proper deposition conditions of ${\mu}c-Si:H$ films for a high-pressure depletion method, Si films were deposited in a combinatorial way using a multi-hollow discharge plasma CVD method. In this paper the substrate temperature dependence of ${\mu}c-Si:H$ film properties are demonstrated. The higher substrate temperature brings about the higher deposition rate, and the process window of device quality ${\mu}c-Si:H$ films becomes wider until $200^{\circ}C$. This is attributed to competitive reactions between Si etching by H atoms and Si deposition.

• Korean Journal of Social Welfare
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• 제63권4호
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• pp.83-107
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• 2011

This study examines the duration dependence in the exit rate from National Basic Livelihood Protection Program(NBLP). If the length of time on welfare is negatively correlated with the exit rate after controlling for 'unobserved heterogeneity', the observed declining exit rates would provide evidence of true duration dependence. Data are drawn from Korean Welfare Panel study 2005~2008. A variety of discrete-time hazard models are estimated, including parametric/nonparametric hazard model, gamma frailty hazard model/mass point technique model. It is found that welfare dynamics in Korea does not show strong evidence of duration dependence after controlling for unobserved heterogeneity. All the models estimated show that this finding is quite robust. The observed declining exit rate is largely due to differences in the unobservable characteristics of recipients. Thus, the detrimental effect of the welfare on the preference and attitude among recipients is not likely to be strengthened as time on welfare increases.

• Journal of Acupuncture Research
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• 제19권4호
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• pp.16-26
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• 2002

Objective : This study was designed to evaluate the decreasing or stop-smoking effect of smoking patients who were given to the auricular acupuncture treatment. Methods : We investigated the smoking patients who serviced Korea Power Engineering Company from March 2002 to April 2002. And one month later we investigated result. Results : In the success rate of low nicotine dependence group, stop-smoking was 28.2%, Above good effect was 57.7%. In the success rate of high nicotine dependence group, stop-smoking was 12.5%, Above good effect was 23.1%. Conclusion : We found that the auricular acupuncture treatment has the decreasing or stop-smoking effect of smoking patients specially to low nicotine dependence group.

• Journal of Oriental Neuropsychiatry
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• 제24권2호
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• pp.179-188
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• 2013

Objectives : The purpose of this study was to compare three therapies - auricular acupuncture, transdermal nicotine patch and therapy - in combination with auricular acupuncture and nicotine patch. Methods : The subjects of this study included 188 male smokers in their 20s, 30s, 40s and 50s, who visited Wonmi Public Health Center. They were evaluated with the Fagerstrom test for nicotine dependence, amounts of daily smoking and success rate of smoking cessation. The subjects decided on a therapy method strictly of their own choice. They were divided into three groups according to the therapy; auricular acupuncture group (62 persons), nicotine patch group (69 persons) and combination therapy group (57 persons). Results : All three groups resulted in statistically significant reducing effects of nicotine dependence and amounts of daily smoking. In the combination therapy group, nicotine dependence was significantly decreased by more than those of the other groups. There were no statistically significant differences in decrements of daily smoking and success rate of smoking cessation among the three groups. Conclusions : The above results suggest that auricular acupuncture and transdermal nicotine patch have significant effects of smoking cessation. If they are combined, it is expected that therapies for smoking cessation would be developed.

• The Bulletin of The Korean Astronomical Society
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• 제45권1호
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• pp.65.3-66
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• 2020

We use the IllustrisTNG cosmological hydrodynamical simulation to study the evolution of star formation rate (SFR)-density relation over cosmic time. We construct several samples of galaxies at different redshifts from z=2.0 to z=0.0, which have the same comoving number density. The SFR of galaxies decreases with local density at z=0.0, but its dependence on local density becomes weaker with redshift. At z≳1.0, the SFR of galaxies increases with local density (reversal of the SFR-density relation), and its dependence becomes stronger with redshift. This change of SFR-density relation with redshift still remains even when fixing the stellar masses of galaxies. The dependence of SFR on the distance to a galaxy cluster also shows a change with redshift in a way similar to the case based on local density, but the reversal happens at a higher redshift, z~1.5, in clusters. On the other hand, the molecular gas fraction always decreases with local density regardless of redshift at z=0.0-2.0 even though the dependence becomes weaker when we fix the stellar mass. Our study demonstrates that the observed reversal of the SFR-density relation at z≳1.0 can be successfully reproduced in cosmological simulations. Our results are consistent with the idea that massive, star-forming galaxies are strongly clustered at high redshifts, forming larger structures. These galaxies then consume their gas faster than those in low-density regions through frequent interactions with other galaxies, ending up being quiescent in the local universe.

• Journal of the Korean Society for Precision Engineering
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• 제13권8호
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• pp.96-101
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• 1996

Glass fiber reinforced polymeric composites hold considerable promise for increased use in low cost high volume applications because of the potential for processing by solid phase forming. Unfortunately, because of the wide variety of such materials, inherent bariability in properties, and complex temperature and strain rate dependence, large strain behavior of these materials has not been well characterized. Of particular importance is failure during processing due to localized necking instability, and it is this phenomenon that is primary focus of this study. The strain rate and temperature dependence is used to predict limiting tensile strains, based on Mackinack imperfection theory. Excellent correlation was obtained between theory and experiment, and the results are summarized in the limit strains as a function of temperature and stain rate.