• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 1994년도 가을 학술발표회 논문집
• /
• pp.127-132
• /
• 1994

This study attemps to investigate the influence of heat of hydration occured during hardening on the strength development of high strength concrete. The concrete design strengths of 500kg/$\textrm{cm}^2$ and 700kg/$\textrm{cm}^2$ were considered to simulated the square columns having $80\times80cm$ and $100\times100cm$, respectively. Both standard curing and field curing specimen were prepared at the specified ages, and the cores were drilled out from the structure. The thermal sensors were installed into the specimen to measure the heat of hydration process occurred during the hardening. This paper tries to uncover the relationship between the temperature history of the concrete and strength development. The correlation of core strength and specimen strength with curing condition is also discussed. Further research is desired to enlight the relationship between strength and heat of hydration of high strength concrete.

• 전기학회논문지P
• /
• 제58권1호
• /
• pp.44-47
• /
• 2009

This paper describes the information for quantitative simulation of weakly ionized plasma. We must grasp the meaning of the plasma state condition to utilize engineering application and to understand materials of plasma state. $SF_6$ gas is widely used in industrial of insulation field. In this paper, $N_2$ is mixed to improve pure $SF_6$ gas characteristics. Electron transport coefficients in $SF_6-N_2$ mixture gases are simulated in range of E/N values from 70 to 400 [Td] at 300K and 1 Torr by using Boltzmann equation method. The results of this method. which are ionization coefficient, attachment coefficient, effective ionization coefficient, and critical E/N, can be important data to present characteristic of gas for insulation. Specially critical E/N is a data to evaluate insulation strength of a gas and is presented in this paper for various mixture ratios of $SF_6-N_2$ mixture gases.

• 조명전기설비학회논문지
• /
• 제25권1호
• /
• pp.50-58
• /
• 2011

In this paper, potential distribution analysis through the six kinds of case studies examined in the environmental conditions change within a limited space, by the power supply system installed. To interpret the potential distribution using electromagnetic field analysis program and the parameters were state of the ground, the outer wall of the configuration state and the presence of human potential distribution was simulated. Potential distribution analysis, the size of nominal voltage, depending on the impedance of human body to be determined on the impact of surprise decision, but if equipped with appropriate protective equipment can be protected from lightning have been confirmed.

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 2002년도 ITC-CSCC -2
• /
• pp.1078-1081
• /
• 2002

In microcell or picocell mobile communication using cellular method, we suggested propagation prediction model which can accurately and rapidly interpret mobile communication propagation environment in urban, when subscriber service is done based on the main road in urban. Further, we simulated suggested propagation prediction model under the hypothesis of urban propagation environment of PCS mobile communication, analyzed receiving field strength by area within a cell, and finally suggested the optimal transmitting power and location condition of microcell or picocell mobile communication base station

• 한국전산유체공학회:학술대회논문집
• /
• 한국전산유체공학회 2003년도 The Fifth Asian Computational Fluid Dynamics Conference
• /
• pp.228-229
• /
• 2003

Complex flow field around the Darius turbine rotating stationally are simulated by solving the three dimensional incompressible Navier-Stokes equation numerically. The rotating coordinate system is employed so that the boundary conditions on the blades of the rotor become simple. In order to impose the boundary condition on the blades precisely, the boundary fitted coordinate system is employed. Fractional step method is used to solve the basic equations. The complex flow fields due to the three dimensionality of the geometry of the turbine and the rotation of the turbine are obtained and they are visualized effectively by using the technique of the computer graphics.

• 한국해양공학회지
• /
• 제10권1호
• /
• pp.65-74
• /
• 1996

Up to now, the existing crack growth modelling has used a mathematical approximation but an assumed function have a great influence on this method. Especially, crack growth behavior that shows very strong nonlinearity needed complicated function which has difficulty in setting parameter of it. The main characteristics of neural network modelling to engineering field are simple calculations and absence of assumed function. In this paper, after discussing learning and generalization of neural networks, we performed crack growth modelling on the basis of above learning algorithms. J'-da/dt relation predicted by neural networks shows that test condition with unlearned data is simulated well within estimated mean error(5%).

• 한국전산유체공학회:학술대회논문집
• /
• 한국전산유체공학회 2007년도 춘계 학술대회논문집
• /
• pp.116-119
• /
• 2007

In this study the unsteady aerodynamic analysis of a hovering helicopter rotor is performed. For the accurate flow field analysis Euler equations and the free wake method are coupled. The Euler equations are solved to find the pressure distribution around the rotor, and free wake method is used to give the boundary condition for the solution of Euler equations. Also, vortex strength and wake motion after the rotor are simulated by the free wake method. The accuracy of the present method is compared with the source sink model. The present method is applied to the hovering Caradonna-Tung rotor and compared with experimental results.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2000년도 춘계학술대회논문집B
• /
• pp.531-534
• /
• 2000

The objective of this investigation is to find effects of the pulsatile flow on the morphological changes of the endothelial cell(E.C.) in blood vessel. The shear flow experiment system is used to get the morphological changes of the E.C. The shapes of E.C. are simulated by the cosine curves and computer simulation is used to calculate the pressure and shear stress fields on the E.C. The inlet boundary condition is given from the measured velocity data of femoral artery. The endothelial cells reduce their heights in the flow field so as to reduce the pressure and wall shear stress on the surface. As the exposed time increases, the shear stress and pressure on the E.C. are reduced under the pulsatile flow. The shear stresses on the cell surface show the minimum values during the deceleration phase.

• 한국공간구조학회:학술대회논문집
• /
• 한국공간구조학회 2005년도 춘계학술발표회 및 정기총회 2권1호(통권2호)
• /
• pp.246-253
• /
• 2005

The design of structural engineering optimization is to minimize the cost. This problem has many objective functions formulating section and shape as a function of the included discrete variables. simulated annealing, genetic algerian and TABU algorithm are searching methods for optimum values. The object of this reserch is comparing the result of TABU algorithm, and verifying the efficiency of TABU algorithm in structural optimization design field. For the purpose, this study used a solid truss of 25 elements having 10 nodes, and size optimization for each constraint and load condition of Geodesic one, and shape optimization of Cable Dome for verifying spatial structures by the application of TABU algorithm

• 한국농공학회지
• /
• 제42권5호
• /
• pp.94-102
• /
• 2000

Investigated was the effectiveness of a constructed wetland system on water quality in Hwa-Ong estruarin reservoir, located in Hwasung-Gun, Kyunggi-Do. Procedures for estimation of pollutant loading from watershed and required area for natural systems, and simulation of corresponding reservoir water quality were reviewed. Generally, simulated reservoir water quality was within the reasonable range, and about 15% of total polder farmland was required to meet the agricultural water quality standards. The model was applied based on the current loading condition without additional treatment systems. Wetland system is an ecologically sound treatment system. Therefore, natural systems can be an alternative measure for water quality improvement in polder projects. The area for natural systems was estimated using literature value which might be acceptable at the planning stage. However, pilot system and its experimental data are requisite for large scale field application. WASP5 was proved to be a useful and versatile model, and its application to estuarine reservoir water quality simulation was thought to be appropriate.