• Geomechanics and Engineering
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• v.21 no.1
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• pp.11-21
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• 2020

The traditional formulations for estimation of bearing capacity in rock mechanics assume a homogeneous and isotropic rock mass. However, it is common that the rock mass consists of different layers of different rock properties or of the same rock matrix with distinct geotechnical quality levels. The bearing capacity of a heterogeneous rock is estimated traditionally through the weighted average. In this paper, the solution of the weighted average is compared to the finite difference method applied to a bilayer rock mass. The influence of different parameters such as the thickness of the layers, the rock type, the uniaxial compressive strength and the overall geotechnical quality of the rock mass on the bearing capacity of a bilayer rock mass is analyzed. A parametric study by finite difference method is carried out to develop a bearing capacity factor in function of the layer thickness and the rock mass quality expressed in terms of the geological strength index, which is presented in a form of a chart. Therefore, this correlation factor allows estimating the bearing capacity of a rock mass that is formed by two layers with distinct GSI, depending on the bearing capacity of the rock mass formed only by the upper layer and considered by that way as homogenous and isotropic rock mass.

• Journal of the Korean Solar Energy Society
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• v.33 no.1
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• pp.32-39
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• 2013

Effects of Weibull shape parameter, k, on capacity factors of wind turbines were investigated. Wind distributions with mean wind speeds of 5 m/s, 6 m/s, 7 m/s and 8 m/s were simulated and used to estimate the annual energy productions and capacity factors of a 2MW wind turbine for various Weibull shape parameters. It was found from the study that the capacity factors of wind turbines are much affected by Weibull shape parameters. When the annual mean wind speed at the hub height of a wind turbine was about 7 m/s, and the air density was assumed to be 1.225 $kg/m^3$, the maximum capacity factor of a 2 MW wind turbine having a rated wind speed of 13 m/s was found to occur with the shape parameter of 2. It was also found that as the mean wind speed increased, the Weibull k parameter which yielded the maximum capacity factor increased. The simulated results were also validated by predictions of capacity factors of wind turbines using wind data measured in complex terrain.

• Journal of the Earthquake Engineering Society of Korea
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• v.11 no.2 s.54
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• pp.11-17
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• 2007

In current seismic design practice, the response modification factor (R-factor) is used as a factor to reduce the elastic base shear demand to the design force level. As is well-known, the R-factor is a committee-consensus factor and, as such, highly qualitative and empirical. The relationship between the R-factor and the connection rotation capacity available in a particular structural system has remained a missing link. In this paper, a rational procedure to evaluate the R-factor is proposed. To this end, the relationship between the available connection rotation capacity and the R-factor is defined and quantified using nonlinear pushover analysis. An RRS steel frame designed according to IBC 2000 was used to illustrate and verify the proposed procedure. Nonlinear time history analysis results indicated that the R-factor definition proposed in this study is generally conservative from design perspective.

• Journal of the Korea institute for structural maintenance and inspection
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• v.5 no.1
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• pp.169-175
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• 2001

Bridge load rating calculations provide a basis for determining the safe load capacity of bridge. Load rating requires engineering judgement in determining a rating value that is applicable to maintaining the safe use of the bridge and arriving at posting and permit decisions. Load testing is an effective means in calculating the rating value of bridge. In Korea, load carrying capacity of bridge is modified by response modification factor that is determined from comparisons of measured values and analysis results. The response modification factor may be corrupted by vehicle location error that is defined as the gap of test vehicle location between load testing and analysis. In this study, the effects of vehicle location error to structural response and response modification factor are investigated, and a new method for evaluating response modification factor is proposed. The random data analysis shows that the proposed method is less sensitive to vehicle location error than the present method.

• Journal of the Korean Society for Railway
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• v.8 no.4
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• pp.367-371
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• 2005

Pile foundations are utilized when soil is so weak that shallow foundations are not suitable or point load is concentrated in small area. Such soil can be formed by the land reclamation works which have extensively been executed along the coastal line of southern and western parts of the Korean Peninsula. The working load at pile is sometimes subjected to not only compression load but also lateral load sad uplift forces. But in most of the practice design, uplift capacity of pile foundation is not considered and estimation of uplift capacity is presumed on the compression skin friction. This study was carried out to determine that the effect of embedment ratio and loading rate on uplift adhesion factor of concrete pile driven in clay. Based on the test results, the critical embedment ratio is about 9. Adhesion factor is constant under the critical embedment ratio, and decreasing over the critical embedment ratio. Also, adhesion factor is increased with the loading rate is increased.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.12 no.4
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• pp.129-134
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• 1992

This paper presents the relation between risk and safety factor for optimal storm sewer design in urban area. For reliability analysis of the storm sewer, uncertainty of the various parameters of constituting equation determining the capacity and load of storm" sewer is considered and risk is determined. In this study, reliability analysis method is applied to Seongsan detention reservoir basin which area is $381,000m^2$ Darcy-Weisbach equation is used for determining capacity of the storm sewer and rational formula is used for determining load. Safety factor representing ratio of the sewer capacity and design flowrate is calculated, and relating with risk. Then risk and safety factor with return period is obtained and it is used for optimal design of storm sewer.

• Wind and Structures
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• v.31 no.4
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• pp.311-319
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• 2020

India is a developing nation and heavily spends on the development of wind power plants to meet the national energy demand. The objective of this paper is to investigate wind power potential of Ennore site using wind data collected over a period of two years by three parameter Weibull distribution. The Weibull parameters are estimated using maximum likelihood, least square method and moment method and the accuracy is determined using R² and root mean square error values. The site specific capacity factor is calculated by the mathematical model developed by three parameter Weibull distribution at different hub heights above the ground level. At last, the wind energy economic analysis is carried out using capacity factor at 30 m, 40 m and 50 m height for different wind turbine models. The analysis showed that the site has potential to install utility wind turbines to generate energy at the lowest cost per kilowatt-hour at height of 50 m. This research provides information of wind characteristics of potential sites and helps in selecting suitable wind turbine.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.2
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• pp.203-210
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• 2003

A simulation study was carried to analyze the vehicle fuel consumption on component basis. Experiments was also carried out to identify the simulation results, under FTP-75 Hot Phase driving conditions. and arbitrary driving conditions. A good quantitative agreement was obtained. Based on the simulation, fuel energy was used in pumping loss(3.7%), electric power generation(0.7%), engine friction(12.7%), engine inertia(0.7%), torque converter loss(4.6%), drivetrain friction(0.6%), road-load(9.2%), and vehicle inertia(13.4%) under FTP-75 Hot Phase driving conditions. Using simulation program, the effects of capacity factor and idle speed on fuel consumption were estimated. A increment of capacity factor of torque converter resulted in fuel consumption improvement under FTP-75 Hot Phase driving conditions. Effect of a decrement of idle speed on fuel consumption was negligible under the identical driving conditions.

• Environmental Analysis Health and Toxicology
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• v.12 no.3_4
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• pp.75-84
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• 1997

Chromatographic retention behavior and separation of various phenol derivatives on a Partisil 10 ODS 3 column-with mobile phase containing $\alpha$-cyclodextrin-were systematically studied. The decrease in k' values caused by the addition of cyclodextrins in the mobile phase was based on the formation of an inclusion complex, resulting in weakening of the hydrophobic interaction between solutes and the stationary phase. The content of the organic solvent in the mobile phase also influenced k' values of the solutes, and k' values increased with a decrease of the content of organic solvent in the mobile phase. A simple equation has been derived that reveals the hyperbolic dependence of the capacity factor on the total concentration of cyclodextrin. A plot of the reciprocal of the capacity factor against (CD)$_T$ gives a straight line and the dissociation constant, K$_D$, of the inclusion complex can be calculated from the slope. The capacity factor decreased with increasing temperature. The enthalpy was calculated from the slope of van't Hoff plots. Under optimum conditions, some mixtures of phenol derivatives were able to separated successfully.

• Journal of the Korea institute for structural maintenance and inspection
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• v.1 no.1
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• pp.53-64
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• 1997

Recently, safety evaluation of structures has received great concern in this country. One major problem in safety evaluation is that the results are often quite different depending upon evaluation authority. This is mainly due to arbitrary selection of various modification factors when employing allowable stress method for safety evaluation, The purpose of the present study is, therefore, to establish a rational method to determine the modification factors, especially the stress modification factor and the deterioration modification factor based on visual examination. It is thought that the proposed method yields a rational and consistent result for safety evaluation and may efficiently be used for realistic evaluation of load capacity of bridge structures.