• Advances in concrete construction
• /
• v.13 no.5
• /
• pp.367-376
• /
• 2022

Theoretical study of vibration distinctiveness of rotating cylindrical are examined for three volume fraction laws viz.: polynomial, exponential and trigonometric. These laws control functionally graded material composition in the shell radius direction. Functionally graded materials are controlled from two or more materials. In practice functionally graded material comprised of two constituent materials is used to form a cylindrical shell. For the current shell problem stainless steel and nickel are used for the shell structure. A functionally graded cylindrical shell is sanctioned into two types by interchanging order of constituent materials from inner and outer side for Type I and Type II cylindrical shell arrangement. Fabric composition of a functionally graded material in a shell thickness direction is controlled by volume fraction law. Variation of power law exponent brings change in frequency values. Influence of this physical change is investigated to evade future complications. This procedure is capable to cater any boundary condition by changing the axial wave number. But for simplicity, numerical results have been evaluated for clamped- simply supported rotating cylindrical shells. It has been observed from these results that shell frequency is bifurcated into two parts: one is related to the backward wave and other with forward wave. It is concluded that the value of backward frequency is some bit higher than that forward frequency. Influence of volume fraction laws have been examined on shell frequencies. Backward and forward frequency curves for a volume fraction law are upper than those related to two other volume fraction laws. The results generated furnish the evidence regarding applicability of present shell model and also verified by earlier published literature.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2001.05a
• /
• pp.859-864
• /
• 2001

For earthquake resistance design, a response modification factor is used to reduce the design strength and it reflects ductility, reserve strength, redundancy and damping effect. But this factor has not theoretical basis. In this study, two response modification factors are compared and analyzed for shear wall apartment building.; the one is introduced by ATC-19 Procedures, the other is suggested FEMA-273 and ATC-40 through nonlinear static analysis. For the results, ATC-19 procedure gives a reasonable estimation to R factor. But $R_{u}$ by using FEAM-273 and ATC-40 methods is estimated so small in case of a minor or moderate earthquake region. Due to this fact, response modification factor is smaller than suggested load criterion 3.0. So, it needs to decrease wall volume and reduce the global strength and system stiffness for proper ductile behavior matching to domestic load criterion.

• Structural Engineering and Mechanics
• /
• v.6 no.6
• /
• pp.613-632
• /
• 1998

A coupling system for a structure accelerating through a fluid is considered which is composed of the structure and the fluid in a finite surrounding volume. Based on the variational principle, the finite element equations of hydrodynamic pressure and structural elastic vibration are deduced. A numerical method is given for the dynamic character and response of the structure which takes the coupled fluid into account. The effect of axial inertial forces on the dynamic character and response of rapidly accelerating structures is also considered.

• Earthquakes and Structures
• /
• v.13 no.3
• /
• pp.241-253
• /
• 2017

In this paper, dynamic response of the horizontal nanofiber reinforced polymer (NFRP) strengthened concrete beam subjected to seismic ground excitation is investigated. The concrete beam is modeled using hyperbolic shear deformation beam theory (HSDBT) and the mathematical formulation is applied to determine the governing equations of the structure. Distribution type and agglomeration effects of carbon nanofibers are considered by Mori-Tanaka model. Using the nonlinear strain-displacement relations, stress-strain relations and Hamilton's principle (virtual work method), the governing equations are derived. To obtain the dynamic response of the structure, harmonic differential quadrature method (HDQM) along with Newmark method is applied. The aim of this study is to investigate the effect of NFRP layer, geometrical parameters of beam, volume fraction and agglomeration of nanofibers and boundary conditions on the dynamic response of the structure. The results indicated that applied NFRP layer decreases the maximum dynamic displacement of the structure up to 91 percent. In addition, using nanofibers as reinforcement leads a 35 percent reduction in the maximum dynamic displacement of the structure.

• Proceedings of the KSME Conference
• /
• 2000.04b
• /
• pp.829-834
• /
• 2000

This paper is primarily directed toward analyzing the transient response characteristics in hydraulic pipe lines. The exact solution to the transient response characteristics was obtained by using the complicated transfer function derived by Iberall. The discrepancy with the exact and approximate is small, so the approximate solution is adopted to the theoretical one. An equation was derived which describes the pressure times relationship Hat occurs at the end of volume terminated transmission line following a sudden pressure change at its inputs. As a result, It is found that the density has relationship about the Wave Propagation is very useful in analyzing the transient response characteristics of hydraulic pipe lines. The velocity of Pressure wave Propagation decreases as the density of fluid increased.

• Journal of Welding and Joining
• /
• v.15 no.6
• /
• pp.105-115
• /
• 1997

A numerical study is performed to predict the thermal response of a detailed card assembly during infrared reflow soldering. The card assembly is exposed to discontinuous infrared panel heater temperature distributions and high radiative/convective heating and cooling rates at the inlet and exit of the oven. The convective, radiative and conduction heat transfer within the reflow oven as well as within the card assembly are simulated and the predictions illustrate the detailed thermal responses. The predictions show that mixed convection plays an important role with relatively high frequency effects attributed to buoyancy forces, however the thermal response of the card assembly is dominated by radiation. The predictions of the detailed card assembly thermal response can be used to select the oven operating conditions to ensure proper solder melting and minimization of thermally induced card assembly tresses and warpage.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.5 no.6
• /
• pp.192-201
• /
• 1997

The feedback control scheme of the pressure control system of the rear wheel steering gear which has relatively large volume and sprung load was built up in order to improve th response characteristic of the system. The control algorithm chosen was a feedback compensator joined by a feedfoward compensator and the model matching method was used in the process of control system design. The structures and properties of the reference models were inspected and the parameters of the controller were decided. The improvement of the response characteristic of the pressure control valve by means of the feedback control is affirmed. Particularly, when the order of the system model is higher than the 2nd order, the effectiveness of the feedback control on the improvement of the response characteristic of the valve is distinct. And the convenience of the model matching method is the process of control system design is confirmed as well.

• Geomechanics and Engineering
• /
• v.25 no.4
• /
• pp.341-345
• /
• 2021

1D sand compression response to ko-loading experiences volume contraction from low to high effective stress regimes. Previous study suggested compressibility model with physically correct asymptotic void ratios at low and high stress levels and examined only for both remolded clays and natural clays. This study extends the validity of Enhanced Terzaghi model for different sand types complied from 1D compression data. The model involved with four parameters can adequately fit 1D sand compression data for a wide stress range. The low stress obtained from fitting parameters helps to identify the initial fabric conditions. In addition, strong correlation between compressibility and the void ratio at low stress facilitates determination of self-consistent fitting parameters. The computed tangent constrained modulus can capture monotonic stiffening effect induced by an increase in effective stress. The magnitude of tangent stiffness during large strain test should not be associated with small strain stiffness values. The use of a single continuous function to capture 1D stress-strain sand response to ko-loading can improve numerical efficiency and systematically quantify the yield stress instead of ad hoc methods.

• Advances in nano research
• /
• v.15 no.6
• /
• pp.579-585
• /
• 2023

This research delves into the intricate dynamics of the flight response exhibited by a golf ball that incorporates nanoparticles with the goal of enhancing its overall quality. The golf ball is meticulously modeled utilizing beam elements, and the impact of nanoparticles is intricately captured through the application of the Halpin-Tsai theory. Employing a numerical solution, the study thoroughly explores the flight response of the golf ball, taking into account the nuanced effects of the embedded nanoparticles. By scrutinizing the aerodynamic characteristics through advanced simulations, this investigation aims to provide valuable insights that could potentially revolutionize the design and performance of golf equipment, offering a pathway towards superior quality and enhanced functionality in the realm of golf ball technology. Results show that increase in the volume percent of nanoparticles, improves the flight response of the golf ball.

• Asian Pacific Journal of Cancer Prevention
• /
• v.15 no.6
• /
• pp.2501-2504
• /
• 2014

Background: Capecitabine is an oral fluoropyrimidine derivative which is frequently used alone or in combination regimens for the treatment of metastatic breast cancer. Although overall and progression free survivals have increased in recent years with the use of new generation drugs, predictive factors that would further improve the outcomes are needed. Previous studies have demonstrated the relation between post-treatment increase in mean corpuscular volume (MCV) and predicting therapy response as well as survival. The present study investigated the clinical impact of MCV elevation in metastatic breast cancer patients treated with capecitabine. Materials and Methods: The data of a total of 82 patients from three centers followed between June 2005 and June 2013 were retrospectively analyzed. The demographic data and hormone receptor status of the patients, as well as initial examination before and after treatment and data concerning progression were recorded. MCV ${\geq}100$ fl was considered as macrocytosis. Capecitabine was given at a dose of $2500mg/m^2$ daily for 14 days every three weeks. Pre-treatment and post-treatment MCV and other parameters of complete blood count were recorded. Post-treatment initial evaluation was performed after 2 cycles of therapy. Results: The median age of the patients was 46.5 years (range 26-72 years) and 54% were premenopausal. Performance status was ECOG 0 and 1 in 81 (99%) patients. The median number of cycles for capecitabine therapy was 5 (min-max: 2-18). The median ${\Delta}MCV$ level (post-treatment values at sixth week - baseline) was 6.4. Whilst ${\Delta}MCV$ was ${\geq}6.4$ in 42 patients, it was <6.4 in 40 patients. Clinical benefit (complete response+partial response+stable disease) was observed in 37 (88%) of 42 patients with a median ${\Delta}MCV$ ${\geq}6.4$ and in 30 (75%) of 40 patients with ${\Delta}MCV$ <6.4 with no statistically significant difference (p=0.158). No significant difference was determined between the group with ${\Delta}MCV$ ${\geq}6.4$ and the group with ${\Delta}MCV$ <6.4 in terms of progression-free survival (11 vs 12 months) (p=0.55) and overall survival (20 months vs. 24 months) (p=0.11). Conclusions: The identification of new predictive markers in metastatic breast cancer is very important. In some recent studies, increase in MCV has been suggested as a marker in tumor response. In the present study, however, no significant difference was determined between tumor response and increase in MCV. Further studies including higher numbers of patients are needed to determine whether increase in MCV is a predictive marker or not.