• Computers and Concrete
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• v.8 no.3
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• pp.343-355
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• 2011

This paper presented the model to predict the chloride diffusion coefficient in tension zone of plain concrete under flexural cyclic load. The fictitious crack based analytical model was used together with the stress degradation law in cracked zone to predict crack growth of plain concrete beams under flexural cyclic load. Then, under cyclic load, the chloride diffusion, in the steady state and one dimensional regime, through the tension zone of the plain concrete beam, in which microcracks were formed by a large number of cycles, was simulated with assumptions of continuously straight crack and uniform-size crack. The numerical analysis in terms of the chloride diffusion coefficient, $D_{tot}$, normalized $D_{tot}$, crack width and crack length was issued as a function of the load cycle, N, and load level, SR. The nonlinear model as regarding with the chloride diffusion coefficient in tension zone and the load level was proposed. According to this model, the chloride diffusion increases with increasing load level. The predictions using model fit well with experimental data when we adopted suitable crack density and tortuosity parameter.

• Journal of Bio-Environment Control
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• v.32 no.1
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• pp.1-7
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• 2023

Understanding the light environment in greenhouse cultivation and the light utilization characteristics of crops is important in the study of photosynthesis and transpiration. Also, as the plant grows, the form of light utilization changes. Therefore, this study aims to develop a light extinction coefficient model reflecting the plant growth. To measure the extinction coefficient, five pyranometers were installed vertically according to the height of the plant, and the light intensity by height was collected every second during the entire growing season. According to each growth stage in the early, middle, and late stages, the difference between the top and bottom light intensity tended to increase to 69%, 72%, and 81%. When leaf area index and plant height increased, the extinction coefficient decreased, and it showed an exponential decay relationship. Three-dimensional model reflecting the two growth indexes, the paraboloid had the lowest RMSE of 1.340 and the highest regression constant of 0.968. Through this study, it was possible to predict the more precise light extinction coefficient during the growing period of plants. Furthermore, it is judged that this can be utilized for predicting and analyzing photosynthesis and transpiration according to the plant height.

• Journal of Ocean Engineering and Technology
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• v.11 no.2
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• pp.39-47
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• 1997

Creep rate the elevated temperature is known to be controller by the softening process of microstructure especially in the solid solution alloys such as 125 Cr rotor steel. The change of structure is a decreasing process of the free energy of the state including stress, diffusivity of the material, and tmeperature. This study shows that diffusion coefficient, D of 12% Cr rotor steel at 953K with 74.8 MPa is 1.084~3.140*$10^{15}mm^2sec^1$ compared to $1.658*10^{24}mm^2sec^1$at 963K without stress. During creep, the growth of martensite laths accelerates the diffusion coefficient under stress due to incoherency of interface between carbides and matrix.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.34 no.7
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• pp.289-296
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• 1985

The Townsend primary ionization coefficient a was measured by the luminous-flux method using the fact that the intensity of radiant light is proportional to electron density in the townsend discharge domain. The ranges of measurements were 15for He gas and 10

• Journal of Korean Society of Forest Science
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• v.95 no.1
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• pp.131-138
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• 2006

This study was conducted to assess the diameter growth patterns of Quercus mongolica and Quercus variabilis dominant species in natural deciduous forests in Korea. The diameter growth data were collected from 83 destructively sample trees for stem analysis in Gangwon-Do region. The relationship between diameter growth and 14 tree measurements was also analyzed. The average diameter growth rate of dominant trees for both species increased until ages of 15-20 years, and exhibited generally constant trend for subsequent ages. The diameter growth rate of both species ranged from 0.09-0.83 cm/yr across the all ages. Average annual diameter growth for last 5 measurement years was 0.28 cm/yr for Quercus mongolica and 0.27cm/yr for Quercus variabilis. The observed growth rate decreased with decreasing crown class. The difference between diameter growth rates for different crown classes was only statistically significant (p<0.0001) for Quercus mongolica. Pearson correlation coefficient between the diameter growth rate decreased with relative diameter (r=0.64), relative height (r=0.61), exposed crown area (r=0.58) and total crown area (r=0.56) for Quercus mongolica. For Quercus variabilis, Pearson correlation coefficient decreased with dbh (r=0.57), crown width (r=0.55), age (r=0.39), competition index (r=-0.39), and height (r=0.35).

• Journal of Life Science
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• v.15 no.1 s.68
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• pp.15-20
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• 2005

The unstructured model was tested to describe mycelial growth, exopolysaccharide formation, and substrate consumption in submerged mycelial culture of Paeeiliomyees tenuipes C240. The Logistic equation for mycelial growth, the Luedeking-Piret equation for exopolysaccharide formation, and Luedeking­Piret-like equations for glucose consumptions were successfully incorporated into the model. The value of the key kinetic constants were: maximum specific growth rate ${\mu}m,\;0.7281\;h^{-1};$ growth­associated constant for exopolysaccharide production $(\alpha),\;0.1743g(g\;cells)^{-1}$; non-growth associated constant for exopolysaccharide production $(\beta),\;0.0019g(g\;cells)^{-1}\;;$ maintenance coefficient $(m_s),\;0.0572g\;(g\;cells)^{-1}$. When compared with batch experimental data, the model successfully provided a reasonable description for each parameter during the entire growth phase. The model showed that the production of exopolysaccharide in P. tenuipes C240 was growth-associated. The model tested in the present study can be applied to the design, scale-up, and control of fermentation process for other kinds of basidiomycetes or ascomycetes.

• Journal of Forest and Environmental Science
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• v.34 no.3
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• pp.235-241
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• 2018

This study was conducted to find out the growth pattern of Pinus koraiensis plantation over 34 years, focusing on DBH, height, basal area and allometric change. Total increment (TI), mean annual increment (MAI) and correlation coefficient were calculated and compared with stand and dominants. Total increment and mean annual increment of both DBH and height of dominants were bigger than those of stand. The difference was apparently shown bigger in DBH than height. Unlike DBH and height the total increment and mean annual increment of basal area per hectare of dominants were distinctively smaller than those of stand. Furthermore MAI of dominant was increasing until age 42, while MAI of stand increased at early ages and then gradually decreased after culmination like MAIs of DBH and height. MAIs of basal area of dead trees at each measurement tended to increase until early age (18 years in this study), while it reached a peak and gradually decrease after that (21 years in this study). Correlation coefficient between DBH and height tended to decrease as both dominant and stand age and the difference between dominant and stand was not clearly shown over the measurement period. Correlation coefficients between DBH and crown width tended to decrease as the trees age and correlation coefficients of dominant were clearly shown smaller than that of stand. Correlation coefficients of height and crown width also was found to be similar to correlation coefficients between DBH and crown. Meanwhile correlation coefficient of height and crown width dropped more radically than coefficient of DBH and crown width as the trees age.

• Korean Journal of Community Nutrition
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• v.8 no.5
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• pp.763-769
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• 2003

The food-service industry in Korea has experienced remarkable growth during the past few decades. The objectives of this study were to analyze the influence of the food-service industry upon the national economy by using an input-output analysis and to find the industrial position of the food service industry. This paper analysed the economic effect of the food-service industry using 168 items arranged in a transaction table based on producer's prices in the 1995 input-output tables. The results of this study showed that the food-service industry had a major influence on the national economy of Korea. Based on the calculation of the following five coefficients; Korea's production inducement coefficient ranked as 50, its import inducement coefficient ranked as 28, its value added inducement coefficient ranked as 32, its worker inducement coefficient ranked as 2 and its employee inducement coefficient per final demand ranked as 5 in a total of 168 industries.

• Korean Journal of Remote Sensing
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• v.28 no.6
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• pp.653-660
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• 2012

This study classified paddy fields according to rice varieties and monitored temporal changes in rice growth using SAR backscatter coefficients (${\sigma}^{\circ}$). A growing period time-series of backscatter coefficients was set up for nine fine-beam mode RADARSAT-1 SAR images from April to October 2005. The images were compared with field-measured rice growth parameters such as leaf area index (LAI), plant height, fresh and dry biomass, and water content in grain and plants for 45 parcels in Dangjin-gun, Chungnam Province, South Korea. The average backscatter coefficients for early-maturing rice varieties (13 parcels) ranged from -18.17 dB to -6.06 dB and were lower than those for medium-late maturing rice varieties during most of the growing season. Both crops showed the highest backscatter coefficient values at the heading stage (late July) for early-maturing rice, and the difference was greatest before harvest for early-maturing rice. The temporal difference in backscatter coefficients between rice varieties may play a key role in identifying early-maturing rice fields. On the other hand, comparisons with field-measured parameters of rice growth showed that backscatter coefficients decreased or remained on a plateau after the heading stage, even though the growth of the rice canopy had advanced.

• Journal of Welding and Joining
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• v.23 no.6
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• pp.61-66
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• 2005

A probabilistic approach for evaluating failure risk is suggested in this paper. Probabilistic fracture analyses were performed for a pressurized pipe of a Cr-Mo steel reflecting variation of material properties at high temperature. A crack was assumed to be located along the weld fusion line. Probability density functions of major variables were determined by statistical analyses of material creep and creep crack growth data measured by the previous experimental studies by authors. Distributions of these variables were implemented in Monte Carlo simulation of this study. As a fracture parameter for characterizing growth of a fusion line crack between two materials with different creep properties, $C_t$ normalized with $C^*$ was employed. And the elapsed time was also normalized with tT, Resultingly, failure probability as a function of operating time was evaluated fur various cases. Conventional deterministic life assessment result was turned out to be conservative compared with that of probabilistic result. Sensitivity analysis for each input variable was conducted to understand the most influencing variable to the analysis results. Internal pressure, creep crack growth coefficient and creep coefficient were more sensitive to failure probability than other variables.