• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.6D
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• pp.779-784
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• 2011

Freeway FFS (Free-Flow Speed) under the state of LOS (Level of Service) A has been regarded as a homogeneous state to all levels of traffic volume. The features of low-density FFS is served as the basic data for a decision on limited maximal speed, accident analysis, simulation modeling etc. A few researches for the macroscopic characteristics of design and operation speed have been reported, and any study for the microscopic features of freeway free-flow speed under the state of low density has not been done. Therefore, the characteristics of low-density FFS according to the level of traffic volume (1-3 veh/30 sec) and daily hour periods (0-5, 6-8, 9-11, 12-19, 20-23) is microscopically analyzed in this study with huge volume and speed data. It was found that speed distributions are changed and show different behaviors under the conditions of traffic volume levels and daily time periods. V85s (85th percentile speed) at early morning and night periods decrease when levels of traffic volume increase, whereas V85s at day time do not show considerable differences. Especially, FFSs of levels of traffic volume at early morning and night periods, despite low density, is analyzed as heterogeneity, but homogeneity at day time.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.1
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• pp.107-116
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• 2014

A volume density of roughness correction blocks in a channel is defined and the corresponding roughness coefficient(n) is estimated by analyzing the diverse hydraulic characteristics of VR, the product of the average velocity and the hydraulic radius, block Reynolds number ($Re^*$), drag coefficient ($\acute{C}_D$), and the roughness coefficient ($n_b$) of bottom shear. The increase of VR and block Reynolds number causes the exponential decrease of roughness coefficient converged to a constant value as expected. The drag coefficient also exponentially decreases as block Reynolds number increases as well. The drag force is governed by the block shape defined by volume density in high block Reynolds number of turbulent flow region. For more accurate estimation of roughness coefficient the use of the correlation equation of it is required by block Reynolds number and volume density. The regression equations for n-VR, $\acute{C}_D-Re^*$, and $n_b-\acute{C}_D$ are presented. The regression equations of roughness coefficient are also presented by block Reynolds number and volume density. The developed equation of roughness coefficient by block Reynolds number and volume density has practical use by confirming the coincidence between the experimental results and the results of HEC-RAS using the developed equation.

• The Journal of the Acoustical Society of Korea
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• v.24 no.8
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• pp.447-453
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• 2005

Laboratory measurements were performed in a uni-algae medium Cochlodinium polykrikoides (Phytoplankton, dinoflagellates) using an Underwater Ultrasound $(5\~15\;MHz)$ to study Characteristics of Acoustic Backscattering of Harmful algae. In an effort to detect the harmful algal scatterers with population density of less than 300 cells/ml that corresponds to the precaution stage of red tide, backscattered signals from various scatterer-density samples were obtained and analyzed. Correlations between volume backscattering strength (Sv) and population density (cells/ml) of scatterers in the medium have been investigated. Comparison of Volume Backscattering Strengths calculated with the fluid-sphere model [1] and the measured values showed an agreement.

• Journal of Korean Society of Forest Science
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• v.95 no.5
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• pp.595-600
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• 2006

The plot design influences the budgets and the precision of forest inventory results. The objective of this study is to determine the efficiency of estimating forest variables such as tree density, basal area, volume, and species richness based on various plot sizes using fixed-area plot sampling in the natural deciduous forest of Pyeong-Chang County, Gang-won Province, Korea. In this study, 108 reference plots were established with a fixed plot size and shape of 0.09 ha ($30m{\times}30m$). In order to determine the optimal plot size for the interest of variables, each sample plot was established using different shapes (square, circle, and rectangle) and was divided into different plot sizes from 100 to $900m^2$. The mean relative difference (MRD) for the sum of the basal area and volume, and tree density per hectare decreased as plot size increased. But the MRD for three variables were only below 13% at the plot size of $500m^2$. Species richness for each reference stand observed ranging from 2 to 15 species, demonstrated highly positive significant relationships with plot size. The minimum plot size for the estimation of tree density, the sum of the BA and volume was determined to be about $400m^2$, whereas the estimation of species richness required a minimum plot size of $500m^2$.

• Journal of Korean Society on Water Environment
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• v.27 no.1
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• pp.9-18
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• 2011

In this study the optimal volume for non-point source control retention is estimated considering spatio-temporal variation of land surface. The 3-parameter mixed exponential probability density function is used to represent the statistical properties of rainfall events, and NRCS-CN method is applied as rainfall-runoff transformation. The catchment drainage area is divided into individual $30m{\times}30m$ cells, and runoff curve number is estimated at each cell. Using the derived probability density function theory, the stormwater probability density function at each cell is derived from the rainfall probability density function and NRCS-CN rainfall-runoff transformation. Considering the antecedent soil moisture condition at each cell and the spatial variation of CN value at the whole catchment drainage area, the ensemble stormwater capture curve is established to estimate the optimal volume for an non-point source control retention. The comparison between spatio-temporally varied land surface and constant land surface is presented as a case study for a urban drainage area.

• Journal of Powder Materials
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• v.6 no.1
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• pp.81-87
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• 1999

Based on the pore filling theory, the microstructure evolution during liquid-phase sintering has been analyzed in terms of interrelationship between average grain size and relative density. For constant liquid volume fraction, the microsturucture trajectories reduced to a single curve in a grain size(x)-density(y) map, regardless of grain growth constant. The slope of curves in the map was inversely proportional to average pore size, while it increased fapidly with liquid volume fraction. Increase in pore volume fraction retarded the densification considerably, but showed marginal effect on the slope. The activation energy of densification was predicted to be the same as that of grain growth as long as the liquid volume fraction is constant for any temperature range studied. The present analyses on microstricture evolution may demonstrate the usefulness of pore filling theory and provide a guideline for process optimization of liquid-phase sintering.

• Magazine of the Korean Society of Agricultural Engineers
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• v.34 no.3
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• pp.33-42
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• 1992

The shear strength of cohesionless Soils results from particle-to-particle friction and structural resistance by interlocking. And, the shear strength of soils is subjected to vary depending on the internal states and external condtions. If the volume change occurring in the soils and stress-strain relationships under the internal and external changes can accrurately he described, it is possible to predict the behaviors of soils. To accomplish these objectives a series of drained triaxial compression tests and isotropic compression test was performed on the Banwol sand at different relative densities ranging from 20% to 80% and different confining pressures ranging from 0.4kgf/cm$^2$ to l2kgf/cm$^2$. The results and main conclusions of the study are summarized as follows; 1.When the relative density or the confining pressure is increased, the maximum deviator stress is increased. The ratio of the maximum deviator stress and the confining pressure is linearly proportional to the relative density. 2.It is observed that the dilatancy depends not only upon its relative density but also the confining stress, and that the maximum deviator stress is obtained after the diatancy occurs. 3.The volume of sands undergoes initial contraction prior to the dilatancy occurred by strain softening. The dilatancy rate eventually approaches the critical state or a constant volume. 4.At lower strains, Poisson's ratio approaches a certain minimum value regadless of the state of materials. At larger strains, however, the ratio is increased as the relative density is increased. 5.It is observed that the modulus of elasticity is linearly proportional to the relative density and the pressure. 6.When the relative density is increased, the friction angle of sands is linearly increased. 7.When the relative density is increased, the expansion index and the compression index are linearly decreased, and the ratio of the two is about 1/3.

• The Korean Journal of Physiology
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• v.4 no.2
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• pp.37-44
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• 1970

Human body volumes were calculated from the measurments of body height and body weight. Equations Suited to express the relations of height, weight, and surface area to show the body volume were derived from the body volume measurements by means of underwater. weighing method. Underwater body weights were corrected for the residual volume of long obtained by the Rahn's three breath method. Underwater weighing was performed on 173 male subjects aged between 13 and 51 years. Subjects were divided into 4 age groups, namely, 13-16 years group of 47 subjects, 16-19 years group of 46 subjects, adult group aged between 22 and 38 years comprising 45 subjects, and middle-aged group (40-51 years) of 35 subjects. The group division was made on .the basis of physical growth and development. The following results were obtained. 1. Body height (H, cm), body weight (W, kg), body surface area $S,\; m^{2})$, and body volume (V, liter.) interrelated closely. V/S showed a high correlation with W/H and the coefficient of correlation was r=0.97 irrespective of age group differences of the subjects. The coefficients of correlation between V/S and W/H in the total mate subjects as a single group was r=1.983. Subsequently the following regression equation was obtained. V = S X (54.84 W/H + 14.08) The agreement of body volume values obtained by the calculation and underwater weighing in the total subject group was better than that of the separate age group division. 2. The calculated values of body volume were: 40.4 l (euiqvalent to the body density value of 1.0562 kg/1) in 13-16 years group; 52.0 l (equivalent to density value of 1.0723 kg/l) in 16-19 years group; 55.3 l (equivalent to density value of 1.0570 kg/l) In the adult group; and 54. 0 l (equivalent to density value of 1.074 kg/l) in the middle-age group. The mean deviation of calculated from the measured volume value ranged between ${\pm}0.55$ and ${\pm}0.81$ liters. 3. The correlation between V/S and mean skinfold thickness of 4 sites (arm, back, iliac and chest) was high, namely, the coefficient of correlation was r=0.656. The coefficients of correlation between V./S and the $R\"{o}hrer$ index ranged between r=0.668 and r=0.810 affected by the difference in group age of the subject. The body volume (V) alone correlated poorly than V/S with mean skinfold thickness (r=0.606) and the $R\"{o}hrer$ index (r ranged between 0.274 and 0.588).

• Progress in Superconductivity and Cryogenics
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• v.16 no.1
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• pp.19-22
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• 2014

The effects of Mg content on the pore formation, density and critical properties were investigated in in-situ reacted $MgB_2$ superconductors. The $Mg_{1+x}B_2$, (x=-0.2, 0.0, 0.05, 0.3, 1.0) bulk samples with different Mg contents were heat-treated at $900^{\circ}C$ for 1 h in an Ar atmosphere. The dimensional changes of a pellet's mass and volume after heat-treatment were measured. After heat-treatment process, the sample mass was decreased by Mg evaporation, but the sample volume was expanded by pore formation at the Mg site; therefore, the apparent density was decreased. Spherical pores the same as Mg particles were developed after heat-treatment in all samples, and the pore density was increased with increasing Mg content. As the x of Mg content was increased to 1.0, the apparent density of $Mg_{1+x}B_2$ samples was decreased due to a relatively larger reduction in a mass change. The critical current density of Mg excessive sample of x=0.05 showed the highest values over the applied magnetic fields because the excessive Mg may compensate Mg loss and enhance grain connectivity.

• Journal of the Korean Wood Science and Technology
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• v.51 no.3
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• pp.222-237
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• 2023

Eucalyptus pellita is one of the fast-growing tree species and has become predominant in Indonesian forest plantations. Meanwhile, tree breeding programs with clone development are the best way to provide greater genetic advantages. A better understanding of genetic control on growth and basic density in E. pellita is important for increasing wood productivity and quality. In this study, growth characteristics (tree height, diameter, and volume), basic density and its genetic parameters (heritability, genetic gain and genetic correlation) were determined. The number of clones tested in both trials was 50, divided into 5 blocks, and 5 trees/plot. The results showed that there were significant differences in growth and basic density among clones. There was an interaction between genetics and the environment further indicating the existence of unstable clones. The high heritability was found in tree height (0.82-0.86), diameter (0.82-0.90), and basic density (0.91-0.93). This implies that E. pellita has good opportunities for genetic improvement to increase wood productivity and quality. In addition, the results of genetic correlations among growth characteristics (height, diameter, and volume) and basic density showed positive moderate to highly significant value. It is suggested that these characters may be used to the advantage of the breeder for bringing improvement in these traits simultaneously. Therefore, this study provides important information of the genetic improvement of wood quality in E. pellita in Indonesia.