• Computers and Concrete
• /
• 제3권1호
• /
• pp.17-28
• /
• 2006

Replacement of actual stress distribution in a reinforced concrete (RC) flexural member with a simpler geometrical shape, which maintains magnitude and location of the resultant compressive force, is an acceptable conceptual trick. This concept was originally perfected for normal strength concrete. In recent years, high strength concrete (HSC) has been introduced and widely used in modern construction. The stress block parameters require updating to account for special features of HSC in the design of flexural members. In future, more varieties of concrete may be developed and a corresponding design procedure of RC flexural members will be required. The usual practice is to conduct large number of experiments on various sizes of specimen and then evolve an empirical relation. This paper presents a numerical procedure through which the stress block parameters can be numerically derived for a given strain ratio variation. The material model for concrete is presented and computational procedure is described. This procedure is illustrated with several variations of strain ratio. The advantages of numerical procedure are that it costs less and it can be used with new material models for any new variety of concrete.

• Structural Engineering and Mechanics
• /
• 제58권1호
• /
• pp.181-197
• /
• 2016

In this paper, we investigated the propagation of surface waves in a nonhomogeneous rotating fibre-reinforced viscoelastic anisotropic media of higher order of nth order including time rate of strain. The general surface wave speed is derived to study the effect of rotation on surface waves. Particular cases for Stoneley, Love and Rayleigh waves are discussed. The results obtained in this investigation are more general in the sense that some earlier published results are obtained from our result as special cases. Also results for homogeneous media can be deduced from this investigation. For order zero our results are well agreed to fibre-reinforced materials. Also by neglecting the reinforced elastic parameters, the results reduce to well known isotropic medium. It is also observed that, surface waves cannot propagate in a fast rotating medium. Comparison was made with the results obtained in the presence and absence of rotation and parameters for fibre-reinforced of the material medium Numerical results are given and illustrated graphically. The results indicate that the effect of rotation and parameters for fibre-reinforced of the material are very pronounced.

• Smart Structures and Systems
• /
• 제18권5호
• /
• pp.931-953
• /
• 2016

In this paper, the effects of mass eccentricity of superstructure as well as stiffness eccentricity of isolators on the amplification of seismic responses of base-isolated structures are investigated by using mathematical near-fault pulse models. Superstructures with 3, 6 and 9 stories and aspect ratios equal to 1, 2 and 3 are mounted on a reasonable variety of Triple Concave Friction Pendulum (TCFP) bearings considering different period and damping ratio. Three-dimensional linear superstructure mounted on nonlinear isolators are subjected to simplified pulses including fling step and forward directivity while various pulse period ($T_p$) and Peak Ground Velocity (PGV) amounts as two crucial parameters of these pulses are scrutinized. Maximum isolator displacement and base shear as well as peak superstructure acceleration and drift are selected as the main engineering demand parameters. The results indicate that the torsional intensification of different demand parameters caused by superstructure mass eccentricity is more significant than isolator stiffness eccentricity. The torsion due to mass eccentricity has intensified the base shear of asymmetric 6-story model 2.55 times comparing to symmetric one. In similar circumstances, the isolator displacement and roof acceleration are increased 49 and 116 percent respectively in the presence of mass eccentricity. Furthermore, it is demonstrated that torsional effects of mass eccentricity can force the drift to reach the allowable limit of ASCE 7 standard in the presence of forward directivity pulses.

• 제어로봇시스템학회논문지
• /
• 제6권1호
• /
• pp.66-72
• /
• 2000

As the demand for the design of modular manipulators or special purpose manipulators has increased, task based design to design an optimal manipulator for a given task become more and more important. However, the complexity with a large number of design parameters, and highly nonlinear and implicit functions are characteristics of a general manipulator design. To achieve the goal of task based design, it is necessary to develop a methodology to solve the complexity. This paper addresses how to determine the kinematic parameters of a two-degrees of freedom manipulator with parallelogram five-bar link mechanism from a given task, namely, how to map a given task into the kinematic parameters. With simplified example of designing a manipulator with five-bar link mechanism, the methodology for task based design is presented. And it introduces formulations of a given task and manipulator specifications, and presents a new dexterity measure for manipulator design. Also the optimization problem with constraints is solved by using a genetic algorithm that provides robust search in complex spaces.

• Structural Engineering and Mechanics
• /
• 제36권6호
• /
• pp.715-727
• /
• 2010

An experimental investigation is conducted here to study the effects of applying frictional sliding fuses (FSF) in concrete infilled steel frames. Firstly, the influences of some parameters on the behavior of the sliding fuse are studied: Methods of adjusting the FSF for a certain sliding strength are explained and influences of time duration, welding and corrosion are investigated as well. Based on the results, time duration does not significantly affect the FSF, however influences of welding and corrosion of the constitutive plates are substantial. Then, the results of testing two 1/3 scale single-storey single-bay concrete infilled steel frames having FSF are presented. The specimens were similar, except for different regulations of their fuses, tested by displacement controlled cyclic loading. The results demonstrate that applying FSF improves infill behaviors in both perpendicular directions. The infilled frames with FSF have more appropriate hysteresis cycles, higher ductility, much lower deteriorations in strength and stiffness in comparison with regular ones. Consequently, the infills, provided with FSF, can be regarded as an engineered element, however, special consideration should be taken into the affecting parameters of their fuses.

• 대한원격탐사학회지
• /
• 제21권5호
• /
• pp.371-382
• /
• 2005

We present a processing system for the Atmospheric Infrared Sounder (AIRS) sounding suite onboard Aqua satellite. With its unprecedented 2378 channels in IR bands, AIRS aims at achieving the sounding accuracy of radiosonde (1 K in 1-km layer for temperature and $10\%$ in 2-km layer for humidity). The core of the processor is the International MODIS/AIRS Processing Package (IMAPP) that performs the geometric and radiometric correction for generation of Level 1 brightness temperature and Level 2 geophysical parameters retrieval. The processor can produce automatically from received raw data to Level 2 geophysical parameters. As we process the direct-broadcast data almost for the first time among the AIRS direct-broadcast community, a special attention is paid to understand and verify the Level 2 products. This processor includes sub-systems, that is, the near real time validation system which made the comparison results with in-situ measurement data, and standard digital information system which carry out the data format conversion into GRIdded Binary II (GRIB II) standard format to promote active data communication between meteorological societies. This processing system is planned to encourage the application of geophysical parameters observed by AIRS to research the aqua cycle in the Korean peninsula.

• Coupled systems mechanics
• /
• 제11권2호
• /
• pp.107-119
• /
• 2022

The aim of the work presented in this paper is development of numerical model for prediction of temperature distribution in pavement according to the measured meteorological parameters, with introduction of non-linear heat transfer coefficient which is a function of temerature difference between the air and the pavement. Developed model calculates heat radiated from the pavement back in the air, which is an important part of the heat trasfer process in the open air surfaces. Temperature of the pavement surface, heat radiation together with many meteorological parameters were measured in series during two years in order to validate the model and calibrate model parameters. Special finite element method for temperature heat transfer towards the soil together with the time integration scheme are used to solve the governing equation. It is proved that non-linear heat transfer coefficient, which is a function of time and temperature difference between the air and the pavement, is required to decribe this phenomena. Proposed model includes heat tranfer coefficient callibration for specific climate region, through the iterative inverse procedure.

• Asian-Australasian Journal of Animal Sciences
• /
• 제22권12호
• /
• pp.1609-1613
• /
• 2009

The objective of this study was to estimate genetic parameters for racing performance traits of thoroughbredracehorses, using a total of 58,124 racing records of 4,200 horses at Gwacheon Racing Park collected from January 2002 to December 2006. This study measured start one furlong time, last three and last one furlong times, and the resulting furlong time averages were 14.2 seconds, 39.9 seconds and 13.9 seconds, respectively. Furlong time means a split time measured based on a 1/8-mile (or approximately 201 m) distance and finished time means total racing time measured from start position to finish line. In the shortest distance races of 1,000 m, the average last three and last one furlong time was fastest at 38.7 seconds and 13.6 seconds, respectively. The correlation between finished time and start one furlong time decreased as the race distance increased, and the same trend was recognized from the correlation between finished time and last three furlong time. In short distance races of 1,400 m or less, the starting ability was found to be an important trait. The average speed was highest at 56 km/h for a 1,000 m race and lowest at 53.2 km/h for a 1,700 m race. Heritabilities of the start one furlong time, the last three and last one furlong time were estimated to be 0.337, 0.245 and 0.210, respectively; and repeatabilities for them were 0.452, 0.353 and 0.309, respectively. Phenotypic and genetic correlations between the start and the last one furlong time were negative at -0.141 and -0.155, respectively.

• 한국해양공학회지
• /
• 제27권2호
• /
• pp.59-68
• /
• 2013

Because of the recent increase in maritime cargo capacity, the production and price of crude oil have been rising. As oil prices have risen, many problems have occurred in the industry. To solve these problems, marine resources are being actively developed, and there has been an increase in the orders for special vessels and marine structures for the development of marine resources. However, consequently, various kinds of accidents have also occurred in these special vessels and structures. One of the major types of accidents involves fire and explosion, which cause many casualties and property damage. Therefore, various studies to estimate and prevent such accidents have been carried out. In this study, as basic research for the prevention of fire and explosion, numerical simulations on combustion were carried out by using a commercial grid generation program, Gridgen, and a CFD program, ANSYS-CFX. The influences of some parameters, such as the grid system, turbulence model, turbulent dissipation rate, and so on, on the simulation results were investigated, and optimum ones were chosen. It was found that the present results adopting these parameters agreed moderately well with other experimental and numerical ones.

• Nuclear Engineering and Technology
• /
• 제56권2호
• /
• pp.552-557
• /
• 2024

The actual swelling of AgInCd absorber might exceed the predicted swelling value after years of service in pressurized water reactors, and the chemical and microstructural changes of AgInCd absorber induced by transmutation reactions are the main reason for the swelling acceleration of AgInCd absorber. In the present study, a model for calculating the irradiation swelling of AgInCd absorber in nuclear control rods is developed according to chemical and microstructural changes of AgInCd absorber. In this model, the chemical compositions of AgInCd absorber as a function of the thermal neutron fluence are firstly calculated, and then the volume of AgInCd absorber after irradiation is obtained on the basis of the crystallographic parameters of phases in the AgInCd absorber, and the irradiation swelling of AgInCd absorber is finally calculated. The crystallographic parameters can be obtained by preparing the simulated AgInCd alloys and fitting the experimental data. The model calculating results of irradiation swelling are in good agreement with the actual swelling data in literature. More importantly, the present model can well explain the EPRI results of the acceleration in the diametral swelling rate above 6-8 × 10²⁰ n/cm² and the decrease in the diametral swelling rate above about 2 × 10²¹ n/cm².