• Transactions of the Korean Society of Mechanical Engineers B
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• v.29 no.7 s.238
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• pp.861-867
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• 2005

In order to develop oxy-fuel combustor, the Flame length characteristic of $CH_4$ with oxidizer of air and oxygen has been experimentally investigated for tile nozzle diameters of 1.6mm, 2.7mm, 4.4mm and 7.7mm. The structure of $CH_4$ flame with oxidizer of oxygen was sharp in contrast with the $CH_4$ flame with oxidizer of air. The stability of $CH_4$ flame with oxidizer of oxygen was higher than $CH_4$ flame with oxidizer of air. In all $CH_4$ flames with oxidizer of air and oxygen, the flame length were dependent on the flowrate in laminar flame regime, and in turbulent flame dependent on the initial jet diameter. Using correlation equation of Delichatsios, the flame length has been expected exactly for $CH_4$ flame with oxidizer of air, but underestimated for $CH_4$ flame with oxidizer of oxygen. This paper proposed correlation equation of $CH_4$ flame with oxidizer of oxygen.

• Nuclear Engineering and Technology
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• v.44 no.6
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• pp.639-652
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• 2012

A three-dimensional discrete fracture network model was developed in order to simulate the hydraulic characteristics of a granitic rock mass at Korea Atomic Energy Research Institute (KAERI) Underground Research Tunnel (KURT). The model used a three-dimensional discrete fracture network (DFN), assuming a correlation between the length and aperture of the fractures, and a trapezoid flow path in the fractures. These assumptions that previous studies have not considered could make the developed model more practical and reasonable. The geologic and hydraulic data of the fractures were obtained in the rock mass at the KURT. Then, these data were applied to the developed fracture discrete network model. The model was applied in estimating the representative elementary volume (REV), the equivalent hydraulic conductivity tensors, and the amount of groundwater inflow into the tunnel. The developed discrete fracture network model can determine the REV size for the rock mass with respect to the hydraulic behavior and estimate the groundwater flow into the tunnel at the KURT. Therefore, the assumptions that the fracture length is correlated to the fracture aperture and the flow in a fracture occurs in a trapezoid shape appear to be effective in the DFN analysis used to estimate the hydraulic behavior of the fractured rock mass.

• Journal of Oral Medicine and Pain
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• v.7 no.1
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• pp.59-65
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• 1982

For the purpose of estimation of age based on changes in the human root dentin transparency, 173 extracted teeth in each part of upper & lower Lt. & Rt. central, lateral incisors to Lt. & Rt. 2nd premolars were evaluated and analized in terms of root dentin transparency. The results are as follows : 1. It was reconfirmed that there exisits coparatively close correlatonship between age and the root dentin transparency. 2. It was proved that the correlation between the changes in the length and the area of the root dentin transparecy in accordance with the ages of each tooth was highest at the upper central incisor, and next at the low central incisor and the upper second premoloar respectively. 3. In the analysis of the age of the transparency, the error was less in the measurement of the area than in the measurement of the length in regard to the estimation of age. 4. The results from the test of the upper central incisor were boiled down to the following linear equation about the correlation among the area and the length of the transparency, and the age: Y=6.94X+14.7(r=0.59) (Y:estimated age, X:length mm) Y=138.47X+12.31(r=0.72) (Y:estimeted age, $X:area\textrm{cm}^2$)

• Development and Reproduction
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• v.16 no.4
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• pp.309-314
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• 2012

This study was conducted to analyze the difference of body types within and between wild and farmed populations of olive flounder Paralichthys olivaceus using measured records of morphological traits. The results showed that surveyed traits and standard deviation were $1,355{\pm}742g$ of body weight, $48.01{\pm}7.79cm$ of total length, and $40.96{\pm}6.80cm$ of body length. Also body height, body shape index and condition factor were $17.19{\pm}3.43cm$, $9.99{\pm}0.74$ and $11.16{\pm}1.54$, respectively. As result of least squares mean and standard error for each trait assumed in this study, those of farmed population showed significantly higher than those of wild population in all traits, exclusively in total length and body length (p<0.01). Particularly, the values of the body height and the body weight of the farmed population were higher than those of the wild population in the same total length. And the phenotypic correlation coefficients of the body weight, the total length, the body length and the body height showed strong positive correlation in all populations. These result suggested that morphological differences exist in farmed and wild flounder. Therefore, introduction of wild flounder is essential for the future production to improve the body type of farmed flounder, and parental fish should be chosen by considering selection of commercially important traits in the production process.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.21 no.1
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• pp.29-35
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• 2015

Background: The purpose of this study was conducted to investigate the effect of incidence of ankle sprains on both leg length inequalities and range of motion of ankle joint in 20's female university students. Methods: 20's female university students were targeting 32 people attending K university in Gwangju. Both leg length inequality was measured using a tape measure, ranges of motion of ankles was measured using a goniometer. Results: The ankle sprain incidence was quite high, with 56.25% (n=18) for the right ankle, 34.38% (n=11) for the left ankle, and 9.38% (n=3) for both. As for the difference between the ankle sprain incidence and both leg length, the average value of the right leg was $83.08{\pm}3.69$, the average value of the left leg was $84.28{\pm}3.27$, making the right leg shorter than the left by 1.2cm with a higher incidence and showing a positive statistical correlation between the two (p<.05). Also showed that there was a negative statistical correlation between ankle sprain incidences and the inversion range of motion spread of the right ankle (p<.05). Conclusion: The incidence of ankle sprains was higher for the larger the difference between both leg length inequality. In addition, the smaller the inversion range of motion spread of the right ankle, the higher the incidence of ankle sprains. Therefore, The evidence suggests that the incidence of ankle sprains can be reduced by recommending stability and efficient exercises that take into consideration the both leg length as well as the ranges of motion of ankle joints.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.11
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• pp.513-520
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• 2018

This research concerns the characteristics of tank barrel inner flow according to the barrel length and the pressure of ammunition when fired. By analyzing the flow characteristics of the bore evacuator according to barrel length and ammunition pressure regarding ammunition design, it is possible to prevent the flareback phenomenon that may occur during ammunition operation. Through bore evacuator flow analysis by barrel length and ammunition pressure, we identified key design factors concerning barrel and ammunition compatibility including speed, accuracy, penetration performance and range. Test results found if barrel length is long and ammunition pressure is low, bore evacuator operation time is slow. Therefore, there is a high probability that propellant gas will enter the battle vehicle. Therefore, the correlation analysis method of bore evacuator flow characteristics based on barrel length and ammunition pressure is considered as a primary method to improve operational performance. When designing new ammunition, the correlation analysis method will be used to determine ammunition weight and select the propellant pressure.

• Journal of Sericultural and Entomological Science
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• v.28 no.2
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• pp.21-27
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• 1986

Since the estimate of the genetic relations between characters gave us effective basic informations about the selection of good strains of silkworm, the experiment was carried out to estimate the heritability and the genotypic correlation, etc. using the 21 combinations F1, 's by diallel crosses of seven strains of the silkworm. As the result of this experiment some conclusions obtained were as follows ; 1. The genotypic correlation is estimated highly positive in the heritability for all the 9 characters. 2. The correlations between all the characters are positive and the genotypic correlation is generally higher than the phenotypic one. 3. Since all the correlations between the have length and other characters are highly positive, it can be considered that the effects of the other characters on the have length are very important.

• Structural Engineering and Mechanics
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• v.20 no.3
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• pp.293-312
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• 2005

In this paper, free vibration of rotating beam with random properties is studied. The cross-sectional area, elasticity modulus, moment of inertia, shear modulus and density are modeled as random fields and the rotational speed as a random variable. To study uncertainty, stochastic finite element method based on second order perturbation method is applied. To discretize random fields, the three methods of midpoint, interpolation and local average are applied and compared. The effects of rotational speed, setting angle, random property variances, discretization scheme, number of elements, correlation of random fields, correlation function form and correlation length on "Coefficient of Variation" (C.O.V.) of first mode eigenvalue are investigated completely. To determine the significant random properties on the variation of first mode eigenvalue the sensitivity analysis is performed. The results are studied for both Timoshenko and Bernoulli-Euler rotating beam. It is shown that the C.O.V. of first mode eigenvalue of Timoshenko and Bernoulli-Euler rotating beams are approximately identical. Also, compared to uncorrelated random fields, the correlated case has larger C.O.V. value. Another important result is, where correlation length is small, the convergence rate is lower and more number of elements are necessary for convergence of final response.

• Geomechanics and Engineering
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• v.23 no.1
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• pp.15-30
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• 2020

The probabilistic bearing capacity of a strip footing placed on the edge of a purely cohesive reinforced soil slope is computed by combining lower bound finite element limit analysis technique with random field method and Monte Carlo simulation technique. To simulate actual field condition, anisotropic random field model of undrained soil shear strength is generated by using the Cholesky-Decomposition method. With the inclusion of a single layer of reinforcement, dimensionless bearing capacity factor, N always increases in both deterministic and probabilistic analysis. As the coefficient of variation of the undrained soil shear strength increases, the mean N value in both unreinforced and reinforced slopes reduces for particular values of correlation length in horizontal and vertical directions. For smaller correlation lengths, the mean N value of unreinforced and reinforced slopes is always lower than the deterministic solutions. However, with the increment in the correlation lengths, this difference reduces and at a higher correlation length, both the deterministic and probabilistic mean values become almost equal. Providing reinforcement under footing subjected to eccentric load is found to be an efficient solution. However, both the deterministic and probabilistic bearing capacity for unreinforced and reinforced slopes reduces with the consideration of loading eccentricity.

• Geomechanics and Engineering
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• v.17 no.6
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• pp.565-572
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• 2019

Spatial variability is an inherent characteristic of soil, and auto-correlation length (ACL) is a very important parameter in the reliability or probabilistic analyses of geotechnical engineering that consider the spatial variability of soils. Current methods for estimating the ACL need a large amount of laboratory or in-situ experiments, which is a great obstacle to the application of random field theory to geotechnical reliability analysis and design. To estimate the ACL reasonably and efficiently, we propose a micro-structure based numerical simulation method. The quartet structure generation set algorithm is used to generate stochastic numerical micro-structure of soils, and scanning electron microscope test of soil samples combined with digital image processing technique is adopted to obtain parameters needed in the QSGS algorithm. Then, 2-point correlation function is adopted to calculate the ACL based on the generated numerical micro-structure of soils. Results of a case study shows that the ACL can be estimated efficiently using the proposed method. Sensitivity analysis demonstrates that the ACL will become stable with the increase of mesh density and model size. A model size of $300{\times}300$ with a grid size of $1{\times}1$ is suitable for the calculation of the ACL of clayey soils.