• 한국연소학회:학술대회논문집
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• 2000.12a
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• pp.113-122
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• 2000

Dynamic structures of unsteady $CH_4$/Air jet diffusion flames with flame-vortex interaction were numerically investigated. A time-dependent, axisymmetric computational model was adopted for this calculation. Two step global reaction mechanism which considers 6 species, was used to calculate the reaction rates. The predicted results including gravitational effect show that the large outer vortices and the small inner vortex street can be well simulated without any additional disturbances in the downstream of nozzle tip. It was found that the temperature and species concentrations had various values for the same mixture fraction in flame-vortex interaction region. This unsteady jet flame configuration accompanying flame-vortex interaction is expected to give good implications for the structure of turbulent flames.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.43 no.4
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• pp.67-75
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• 2011

Sulfuric acid hydrolysis is a typical approach for producing cellulose nanocrystals. The method has been widely used, but it has a disadvantage of low yield of cellulose nanocrystals compared to mechanical method. To expand the application of cellulose nanocrystals in practical, we should be able to produce them with higher yield and the controlled properties. In this study, therefore, we intended to investigate the effect of sulfuric acid hydrolysis condition on the characteristics of the prepared cellulose nanocrystals. The concentration of sulfuric acid, temperature and hydrolysis time were varied, and the yield as well as diverse properties including the morphology, size and zeta potential were examined. We could obtain cellulose nanocrystals up to 70% of yield and found that the properties were dependent on the reaction condition. It would be helpful to select an appropriate condition for producing cellulose nanocrystals.

• Water for future
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• v.16 no.3
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• pp.181-185
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• 1983

The problem of hydrodynamic pressure on dams during transient earthquake is treated by considering water as being incompressible. A time dependent Green's function is introduced which allows surface waves. The formula of the hydrodynamic pressure due to horizontal and vertical earthquake is derived which permits quantitative determination of the effect of surface waves. Finally, it is found that surface waves may be ignored when the depth of reservoir is large.

• Archives of Pharmacal Research
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• v.13 no.1
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• pp.51-54
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• 1990

Effect of scoparone (6, 7-dimethoxycoumarin) on the hepatic cytosolic sulfotransferase activity was investigated. After treatment with scoparone, hepatic cytosolic sulfotransferase activity was increased with odse and time-dependent manner as compared to control. The $V_{max}$ value (control = 1.33 n moles/mg protein/min, scoparone = 2.39n moles/mg protein/min) without affecting the $K_m$ value for p-nitrophenol was increased by the scoparone treatment. Whereas, the hepatic cytosolic sulfotransferase was not changed by the addition of scoparone in vitro, and was strongly inhibited by the addition of metabolites of scoparone. The results obtained suggest that the characteristics of increase in the enzyme activity may include induction of enzyme proteins, and may be due to the metaboltes of scoparone.

• Proceedings of the KIEE Conference
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• 1989.11a
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• pp.114-118
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• 1989

Due to the increased integration density of VLSI circuits a highly reliable thin oxide film is required to fabricate a small geometry MOS device. The behavior of thermal $SiO_2$ under high electric field and current condition has a major effect on MOS device degration and also the practical use of MOS device under irradiation has cause the degration of thin oxide films. In this paper, in order to evaluate the reliability of thin oxides with no stress applied and stressed by the irradiation under low electric field, the tests of TDDB (Time-dependent-dielectric breakdown) are used. Failure times against electric field are examined and acceleration factor is obtained for each case. Based on the experimental data, breakdown wear out limitation for thin oxide films is characterised.

• Journal of the Korean Wood Science and Technology
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• v.37 no.2
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• pp.141-147
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• 2009

The fluctuation of physical properties in wood or wood composites is an important subject when the materials in building and construction. Sorption and desorption occur in wood when exposed to the open air, and the temperature distribution in wood can fluctuate as a result of changes in environmental temperature, solar radiation, humidity, and wind velocity. In this study, the temperature difference and fluctuation caused by outdoor environment among different wood species were analyzed using a numerical method. The effect on the process of heat transfer in wood caused by environmental factors was investigated using 1-dimensional partial differential equation with real boundary and initial conditions. The experimental data have been used to check the accuracy of programming code. Through analysis, it was found out that density and moisture content have a negative effect on thermal diffusivity of wood.

• Computers and Concrete
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• v.20 no.5
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• pp.511-519
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• 2017

The reliability of reinforced concrete structures is frequently compromised by the deterioration caused by reinforcement corrosion. Evaluating the effect caused by reinforcement corrosion on structural behaviour of corrosion damaged concrete structures is essential for effective and reliable infrastructure management. In lifecycle management of corrosion affected reinforced concrete structures, it is difficult to correctly assess the lifecycle performance due to the uncertainties associated with structural resistance deterioration. This paper presents a stochastic deterioration modelling approach to evaluate the performance deterioration of corroded concrete structures during their service life. The flexural strength deterioration is analytically predicted on the basis of bond strength evolution caused by reinforcement corrosion, which is examined by the experimental and field data available. An assessment criterion is defined to evaluate the flexural strength deterioration for the time-dependent reliability analysis. The results from the worked examples show that the proposed approach is capable of evaluating the structural reliability of corrosion damaged concrete structures.

• Journal of Korean Society for Atmospheric Environment
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• v.15 no.3
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• pp.257-266
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• 1999

In order to analyze the effect of meteorological elements on ozone concentration, we carried out cross-correlation of the elements with ozone concentraton, and time series analysis on them. As a result, it revealed that temperature, wind speed and humidity are not independent variables with ozone concentrations, and also, solar radiation and mixing height are the major elements that affect them. We developed models for ozone with solar radiation and mixing height as dependent variables to verify the effect of major meteorological elements. The predicted ozone concentration has strong correlation coefficients, So, We could conclude that we can predict ozone concentreation only with solar raidation and mixing height as dependents.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.1
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• pp.172-179
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• 1996

For mechanical systems operating at high tempertature, thermal fatigue phenomenon has been recognized as a major cause of mechanical component failures. To evaluate cumulative fatigue damage as a conesquence of thermal fatugue on real time, the stress tranfer function(Green's function) approach is popularly used. The objective of this paper is to investigate the effect of thermophsical properties on the stress tranfer function. For this purpose a modified Green's function approach considering temperature-dependent thermophysical properties is proposed. Two case studies were performed and the proposed approach agrees well with full finite element analysis.

• Herbal Formula Science
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• v.16 no.2
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• pp.155-162
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• 2008

Objectives : The present study was designed to investigate corelation between mix proportion of Scutellaria baicalensis (SB) and Coptis chinensis (CC) on lipopolysaccharide (LPS)-induced TYPE-1 interferon production. Methods : I examined TYPE-1 interferon, interferon regulating factor (IRF)-1,7 and interleukin(IL)-10 production on LPS-induced RAW264.7 cells to evaluate inhibitory effect of mix proportion of SB and CC using real time PCR. Results : Mixture of SB and CC regulated TYPE-1 interferon and IRF-1,7 mRNA expression with SB dose dependent manner, while maintained IL-10 mRNA expression on LPS-induced RAW264.7 cells. Conclusion : In mixture of SB and CC, SB plays a key role in reducing TYPE-1 interferon through inactivation IRF-1,7. Furthermore mixture of SB and CC maintained IL-10 mRNA level. Collectively, this results suggest that SB confer beneficial effects in autoimmune diseases clinically.