• Journal of Welding and Joining
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• 제29권4호
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• pp.73-79
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• 2011

Friction stir welding (FSW) is a solid state joining method patented in 1991 by The Welding Institute (TWI). It is widely used for joining light metals such as Al and Mg alloys. Foreign railway vehicle manufacturing companies have been applying FSW to car body welding, but domestic companies are in the beginning of feasibility study. Therefore, lots of experimental and analytical study is needed. In this study, three-dimensional finite element modeling of the friction stir welding of two Al6061-T6 plates was carried out. And temperature field and residual stresses were obtained and compared to experimental results in the literature. It is found the analytic thermal field is in a good agreement with the experimental results, but there are some differences between numerical and experimental residual stresses.

• 대한통합의학회지
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• 제2권3호
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• pp.23-30
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• 2014

Purpose : The purpose of this study was to grasp the general status and trend of the driving rehabilitation research focusing on interested topics, study subjects, therapeutic approaches, study designs, etc. Methods : It targeted 18 papers published in the RISS (Research Information Service System) from 2000 to 2014, and performed a descriptive statistical analysis by classifying these papers to topics, study subjects, study forms, study designs, study fields, and researchers. Results : As a result of the analysis, for the study form in the driving rehabilitation field, the rate of experimental papers was 61.1%, the highest. Major study subjects turned out to be occupational therapists, the disabled, and the aged, in order. For the study quality and design, the rate of survey and non randomized-single experimental study, which correspond to stage IV, was the highest, and the general study quality was found to be low. For the study field, the rates of the roles and recognition of occupational therapists, evaluation on driving ability of the disabled, and institutional improvement and future measures were the highest, each of which being 16.7%. Conclusion : Through this study, major study subjects and study quality in the driving rehabilitation field could be grasped, and it could be found that for development of the driving rehabilitation field, higher quality researches on more various study subjects would be needed in the future.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2004년도 춘계학술대회 논문집
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• pp.1026-1032
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• 2004

The objective of this study is to confirm the field application of coarse aggregates technology mixtured with high strength mortar under the rail. In the present study, the field tests are performed to find the field state and aggregate gradations and the laboratory tests are performed to find the compressive strength of the pre packed concrete cylinder specimens and the core specimens obtained at the field.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2014년도 제49회 KOSCO SYMPOSIUM 초록집
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• pp.363-365
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• 2014

An experimental study on effect of AC electric field on upwardly spreading flame over electrical wire, which is insulated by Polyethylene(PE), was conducted. The result showed that upwardly spreading flame leaned toward unburned side with angle of inclination. With applied electric field, size of upwardly spreading flame increased significantly. Flame spread rate showed various trends with inclination, applied voltage and frequency.

• 한국자동차공학회논문집
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• 제4권3호
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• pp.1-9
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• 1996

This study investigated torque characteristics for Couette flow experimentally under circumstaces that ferrofluids were between two coaxial spheres. Torque measurement was obtained for the situation where the inner sphere was rotating while the outer sphere was kept stationary. The magnetic field was imposed on the fluid, using a bar magnet which was inserted in the inner sphere. In the laminar flow region the torque increase when the magnetic field is applied and the critical Reynolds number is increased. However, in the transition regime, the effect of the magnetic field on the torque characteristics decrease as Reynolds number increases. The value of torque were the same as those of glycerine solution beyond the cirtical Reynolds number. We also made experimental equation which could obtain coefficient of torque within critical Reynolds number in terms of sphere spacing Reynolds number and magnetic properties of ferrofluid.

• 한국어병학회지
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• 제30권1호
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• pp.51-61
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• 2017

The effect of electromagnetic field on aquatic organisms has received little attention. In the current study, the effect of 50Hz electromagnetic field on muscle histopathology of Caspian Sea Cyprinus carpio, a species of economic importance, was investigated. A total of 120 healthy fish were used in this study. They were classified randomly in one of two groups as follows: Control or unexposed EMF group and experimental group with 5 different magnetic field intensities (0.1, 1, 3, 5 and 7mT) at 2 different exposure times including 30 and 60 minutes. Fish in the experimental group were exposed only once. Two weeks after exposure, dorsal muscles sectioned transversely, stained and were examined using a light microscope. Histopathologic assessments showed significant difference between control and EMF exposed groups at both 30 min. (p<0.01) and 60 min. (p<0.001) exposure times. We report for the first time that electromagnetic field in interaction with muscular tissue of Cyprinus carpio exhibits a dual effect which depends on the field intensity, and exposure time. At short exposure time (30 min.), EMF stimulates muscle growth process. At longer exposure time (60 min.), EMF can damage muscle tissue and result in muscle necrosis. More research is required to elucidate precise mechanisms involved in muscle hypertrophy and pathologic changes.

• Wind and Structures
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• 제5권2_3_4호
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• pp.277-290
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• 2002

A two dimensional discrete vortex method (DIVEX) has been developed at the Department of Aerospace Engineering, University of Glasgow, to predict unsteady and incompressible flow fields around closed bodies. The basis of the method is the discretisation of the vorticity field, rather than the velocity field, into a series of vortex particles that are free to move in the flow field that the particles collectively induce. This paper gives a brief description of the numerical implementation of DIVEX and presents the results of calculations on a recent suspension bridge deck section. The results from both the static and flutter analysis of the main deck in isolation are in good agreement with experimental data. A brief study of the effect of flow control vanes on the aeroelastic stability of the bridge is also presented and the results confirm previous analytical and experimental studies. The aeroelastic study is carried out firstly using aerodynamic derivatives extracted from the DIVEX simulations. These results are then assessed further by presenting results from full time-dependent aeroelastic solutions for the original deck and one of the vane cases. In general, the results show good qualitative and quantitative agreement with results from experimental data and demonstrate that DIVEX is a useful design tool in the field of wind engineering.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• 제26권4호
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• pp.333-342
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• 2022

In this paper, we perform a direct comparison study of real experimental data for domain rearrangement and the Cahn-Hilliard (CH) equation on the dynamics of morphological evolution. To validate a mathematical model for physical phenomena, we take initial conditions from experimental images by using an image segmentation technique. The image segmentation algorithm is based on the Mumford-Shah functional and the Allen-Cahn (AC) equation. The segmented phase-field profile is similar to the solution of the CH equation, that is, it has hyperbolic tangent profile across interfacial transition region. We use unconditionally stable schemes to solve the governing equations. As a test problem, we take domain rearrangement of lipid bilayers. Numerical results demonstrate that comparison of the evolutions with experimental data is a good benchmark test for validating a mathematical model.

• Wind and Structures
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• 제1권4호
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• pp.337-349
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• 1998

A numerical and experimental study was performed for the wind flow field in one area, comprising a group of several pavilions separated by passageways, of the EXPO '98 - a World Exposition (Lisbon, Portugal). The focus of this study is the characterization of the flow field to assess pedestrian comfort. The predictions were obtained employing the Reynolds averaged Navier-Stokes equations with the turbulence effects dealt with the ${\kappa}-{\varepsilon}$ RNG model. The discretization of the differential equations was accomplished with the control volume formulation in a Cartesian coordinate system, and an advanced segregated procedure was used to achieve the link between continuity and momentum equations. The evaluation of the overall numerical model was performed by comparing its predictions against experimental data for a square cylinder placed in a channel. The predicted values, for the practical geometry studied, are in a good agreement with the experimental data, showing the performance and the reliability of the ${\kappa}-{\varepsilon}$ RNG model and suggesting that the numerical simulation is a reliable methodology to provide the required information.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2000년도 춘계학술대회논문집
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• pp.1002-1006
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• 2000

It is diffuse sound field that measuring condition of absorption ratio and sound transmission loss for material consist of building are measured in reverberartion room and on-site. In this study, for upkeeping diffuse sound field in reverberation room, it is measured and etimated that sound field is effected according to sound source lacation and characteristics of emission directivity for sound source.