• 소음진동
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• 제9권2호
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• pp.273-284
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• 1999

The cylindrical shells are used as primary components of complex structures such as airplane fuselages and nuclear pressure vessels. Recently the free vibration analysis of these structures are investigated by many researchers. The engineering informations on experimental validation of the free vibration behavior on the simply supported cylindrical shells are very few. The experimental methods for realizing the physical boundary condition of simply supported edges are examined. Natural frequencies and mode shapes of the isotropic and plain weave composite simply supported shells are obtained by modal tests. A theoretical and finite element analysis are also performed in order to validate the experimental results. The experimental results indicate that the simply supported boundary conditions with bolts along the circumferential direction of shell in both ends are well achieved. Those are shown to agree with the analytical results and with the finite element analysis results. These methods can be used to realize other experimental simple support boundary conditions.

• Interaction and multiscale mechanics
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• 제1권2호
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• pp.177-190
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• 2008

In this paper, both experimental measurement and theoretical analysis are used to investigate the out-of-plane resonant characteristics of a cantilevered piezoceramic plate in air and three different kinds of fluid. The experimental method, amplitude-fluctuation electronic speckle pattern interferometry (AF-ESPI), is the major technique used in this study to measure the resonant characteristics of the cantilivered piezoceramic plate. Both resonant frequencies and full-field mode shapes are obtained from this experimental technique. Numerical computations based on the finite element analysis are presented for comparison with the experimental results. Good quality of mode shapes for the cantilevered piezoceramic plate in air is obtained from the AF-ESPI technique. However, the quality decreases as the viscosity of fluids increases. From the results provided from experimental measurements and numerical computations, it is indicated that the resonant frequencies of the cantilevered piezoceramic plate in fluid decrease with the increase of the viscosity of fluids. Good agreements between the experimental measured data and the numerical calculated results are found for both resonant frequencies and mode shapes of the cantilevered piezoceramic plate in fluid.

• 한국초등과학교육학회지:초등과학교육
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• 제24권5호특별호
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• pp.518-530
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• 2005

The purpose of this study was to investigate the characteristics of pre-service primary teachers' justifying their hypotheses about the brightness of electric bulbs. They conducted their experiments and wrote their experimental results and ideas on their worksheets. The worksheets for generating and evaluating scientific hypothesis were analyzed. Most of them generated the consumption hypothesis and designed the experiments to confirm their hypotheses or directly measure without the change of experimental conditions. The responses for valid experimental designs were $74\%$ of total responses. The $62\%$ of total responses was valid prediction for experimental results. The $60\%$ of pre-service teachers described the experimental results correctly. But other teachers described the biased results or inappropriate results. The $54\%$ of them refuted hypotheses and the $36\%$ confirmed their hypotheses. The theory-based responses were $51\%$ and the evidence-based responses were $47\%$. The $64\%$ of them proposed the possibility of the alternative hypothesis after testing their hypotheses. This study also discussed the implications of these findings for teaching and Loaming in science education.

• 동의생리병리학회지
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• 제26권4호
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• pp.462-468
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• 2012

The present study was conducted with the object of examining how ST36 and LR3 electro acupuncture affects the injured side and the intact side in rats with sciatic nerve injury. For this study, we divided rats into a control group that were injured but not treated, experimental group I that were injured and had electro acupuncture on the intact side, experimental group II that were injured and had electro-acupuncture on the injured side, and experimental group III that were injured and had electro-acupuncture on both the intact side and the injured side, and performed behavioral and immunohistochemical tests. The results of this study are as follows. In the results of hot plate test, on Day 1 of experiment, experimental group I did not show a statistically significant difference but experimental group II and III showed a statistically significant difference, and on Day 2 and 3, all of experimental group I, II and III showed a statistically significant difference. In the results of SFI test, on Day 7 of experiment, experimental group I did not show a statistically significant difference but experimental group II and III showed a statistically significant difference, and on Day 14 and 21, all of experimental group I, II and III showed a statistically significant difference. In the results of immunohistochemical test, the expression of c-fos decreased gradually on Day 1, 2 and 3 in all the experimental groups, and the decrease was larger in the experimental groups that had electro-acupuncture than in the control group. In the results of immunohistochemical test, the expression of BDNF increased gradually on Day 7, 14 and 21 in all the experimental groups, and the expression was higher in the experimental groups than in the control group. Summing up the results, ST36 and LR3 electro acupuncture was effective when it was applied to the injured side and to both sides after sciatic nerve injury, but it was also effective in pain relief and nerve regeneration when it was applied to the intact side.

• Wind and Structures
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• 제25권6호
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• pp.537-549
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• 2017

In this study, the turbulent flow around a bluff body for different wind velocities was investigated numerically by using its two- and three-dimensional models. These models were tested to verify the validity of the simulation by being compared with experimental results which were taken from the literature. Variations of non-dimensional velocities in different positions according to the bluff body height were analysed and illustrated graphically. When the velocity distributions were examined, it was seen that the results of both two- and three-dimensional models agree with the experimental data. It was also seen that the velocities obtained from two-dimensional model matched up with the experimental data from the ground to the top of the bluff body. Particularly, compared to the front part of the bluff body, results of the upper and back part of the bluff body are better. Moreover, after comparing the results from calculations by using different models with experimental data, the effect of multidimensional models on the obtained results have been analysed for different inlet velocities. The calculation results from the two-dimensional (2D) model are in satisfactory agreement with the calculation results of the three-dimensional model (3D) for various flow situations when comparing with the experimental data from the literature even though the 3D model gives better solutions.

• 한국입자에어로졸학회지
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• 제5권1호
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• pp.17-27
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• 2009

Particle deposition on a semiconductor wafer larger than 100 mm was studied experimentally and numerically. Particularly the electrostatic effect on particle deposition velocity was investigated. The experimental apparatus consisted of a particle generation system, a particle deposition chamber and a wafer surface scanner. Experimental data of particle deposition velocity were obtained for a semiconductor wafer of 200 mm diameter with the applied voltage of 5,000 V and PSL particles of the sizes between 83 and 495 nm. The experimental data of particle deposition velocity were compared with the present numerical results and the existing experimental data for a 100 mm wafer by Ye et al. (1991) and Opiolka et al. (1994). The present numerical method took into consideration the particle transport mechanisms of convection, Brownian diffusion, gravitational settling and electrostatic attraction in an Eulerian frame of reference. Based on the comparison of the present experimental and numerical results with the existing experimental results the present experimental method for a 200 mm semiconductor wafer was found to be able to present reasonable data.

• Steel and Composite Structures
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• 제20권6호
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• pp.1305-1322
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• 2016

This paper presents the results of experimental and numerical model analyses on partially encased composite columns under concentric loads. The main objective of this study is to evaluate the influence of replacing the conventional longitudinal and transverse steel bars by welded wire mesh on the structural behavior of these members under concentric loads. To achieve these goals experimental tests on four specimens of partially encased composite columns submitted to axial loading were performed and the results were promising in terms of replacing the traditional reinforcement by steel meshes. In addition, a numerical FE model was developed using the software DIANA$^{(R)}$ with FX+. The experimental results were used to validate the numerical model. Satisfactory agreement between experimental and numerical results was observed in both capacity and deformability of the composite columns. Despite of the simplifying assumptions of perfect bond between steel and concrete, the numerical model adequately represented the columns behavior. A finite element parametric study was performed and parameters including thickness of the steel profile and the concrete and steel strengths were evaluated. The parametrical study results found no significant changes in the partially encased columns behavior due to variations of the steel profile thickness or yield strength. However, significant changes in the post peak behavior were observed when using high strength concrete and these results suggest a change in the failure mode.

• Journal of Mechanical Science and Technology
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• 제17권9호
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• pp.1371-1379
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• 2003

The effects of change in injection pressure on spray structure in high temperature and pressure field have been investigated. The analysis of liquid and vapor phases of injected fuel is important for emissions control of diesel engines. Therefore, this work examines the evaporating spray structure using a constant volume vessel. The injection pressure is selected as the experimental parameter, is changed from 22 MPa to 112 MPa using a high pressure injection system (ECD-U2). Also, we conducted simulation study by modified KIVA-II code. The results of simulation study are compared with experimental results. The images of liquid and vapor phase for free spray were simultaneously taken by exciplex fluorescence method. As experimental results, the vapor concentration of injected fuel is leaner due to the increase of atomization in the case of the high injection pressure than in that of the low injection pressure. The calculated results obtained by modified KIVA-II code show good agreements with experimental results.

• Structural Engineering and Mechanics
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• 제47권2호
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• pp.247-263
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• 2013

It is evident that torsional resistance of a reinforced concrete (RC) member is attributed to both concrete and steel reinforcement. However, recent structural design codes neglect the contribution of concrete because of cracking. This paper reports on the results of an experimental and numerical investigation into the torsional capacity of concrete beams reinforced only by longitudinal rebars without transverse reinforcement. The experimental investigation involves six specimens tested under pure torsion. Each specimen was made using a cast-in-place concrete with different amounts of longitudinal reinforcements. To create the torsional moment, an eccentric load was applied at the end of the beam whereas the other end was fixed against twist, vertical, and transverse displacement. The experimental results were also compared with the results obtained from the nonlinear finite element analysis performed in ANSYS. The outcomes showed a good agreement between experimental and numerical investigation, indicating the capability of numerical analysis in predicting the torsional capacity of RC beams. Both experimental and numerical results showed a considerable torsional post-cracking resistance in high twist angle in test specimen. This post-cracking resistance is neglected in torsional design of RC members. This strength could be considered in the design of RC members subjected to torsion forces, leading to a more economical and precise design.

• Biomaterials and Biomechanics in Bioengineering
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• 제3권1호
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• pp.1-14
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• 2016

Well-ordered porous materials are very promising in orthopedics since they allow tailoring the mechanical properties. Finite element (FE) analysis is commonly used to evaluate the mechanical behavior of well-ordered porous materials. However, FE results generally differ importantly from experimental data. In the present article, three types of manufacturing irregularities were characterized on an additive manufactured porous titanium sample having a simple cubic unit-cell: strut diameter variation, strut inclination and fractured struts. These were included in a beam FE model. Results were compared with experimental data in terms of the apparent elastic modulus (Eap) and apparent yield strength (SY,ap). The combination of manufacturing irregularities that yielded the closest results to experimental data was determined. The idealized FE model resulted in an Eap one order of magnitude larger than experimental data and a SY,ap almost twice the experimental values. The strut inclination and fractured struts showed the strongest effects on Eap and SY,ap, respectively. Combining the three manufacturing irregularities produced the closest results to experimental data. The model also performed well when applied to samples having different structural dimensions. We recommend including the three proposed manufacturing irregularities in the FE models to predict the mechanical behavior of such porous structures.