• Transactions of the KSME C: Technology and Education
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• v.1 no.2
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• pp.179-186
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• 2013

Far-infrared radiation therapies are becoming more popular for blood circulation disorders, cardiovascular disease, skin diseases, inhibit cancer cell, etc replacing conventional operations. In this research, thermal characteristics of heating part in panel radiators, which is effective on the blood circulation disorders were experimentally analyzed. The heating line supplies heat energy to insulation coatings with heat flux of $150mW/m^2$ in normal status and as a result the coatings reached 20% of the heating line temperature. In other words, the insulation itself could increase surface temperature of heating plates by 20% and raise thermal time constant promote blood circulation effect. We also found that space arrangement of the heating lines was an important factor in designing heating parts and both coefficient of heat conduction and density of the heating plate should be also considered for superimpose of thermal diffusion.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.12
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• pp.1738-1746
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• 2002

In the FSI (Fluid-Structure Interaction) problems, two different governing equations are to be solved together. One is fur the fluid and the other for the structure. Furthermore, a kinematic constraint should be imposed along the boundary between the fluid and the structure. We use the combined formulation, which incorporates both the fluid and structure equations of motion into a single coupled variational equation so that it is not necessary to calculate the fluid force on the surface of structure explicitly when solving the equations of motion of the structure. A two-dimensional channel flow divided by a Bernoulli-Euler beam is considered and the dynamic response of the beam under the influence of channel flow is studied. The Navier-Stokes equations are solved using a P2P1 Galerkin finite element method with ALE (Arbitrary Lagrangian-Eulerian) algorithm. The internal structural damping effect is not considered in this study and numerical results are compared with a previous work fer steady case. In addition to the Reynolds number, two non-dimensional parameters, which govern this fluid-structure system, are proposed. It is found that the larger the dynamic viscosity and density of the fluid are, the larger the damping of the beam is. Also, the added mass is found to be linearly proportional to the density of the fluid.

• Polymer(Korea)
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• v.24 no.6
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• pp.837-844
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• 2000

The cure behavior of commercial epoxy molding compounds (EMC) commonly used for IC package was studied at constant cure temperatures as well as at constant heating rates using differential scanning calorimetry (DSC), rheometer, and dielectric analyzer (DEA). The cure kinetics were obtained using autocatalytic reaction model according to the Ryan Dutta method after assuming m+n equal to 2. The prediction of reaction rates by the model equation corresponded well to experimental data at all temperatures except for 10$0^{\circ}C$. The phase transitions such as gelation and vitrification occurred during network formation. At each isothermal cure temperature, $T_{g}$ was measured in accordance with cure time, and the vitrification point was attained when $T_{g}$ was equal to $T_{cure}$. The temperature dependence of gel points and vitrification points showed good agreement with Arrhenius relation. DEA using parallel plate electrode was effective for the monitoring of EMC cure. we knew that if the resin systems are materials of comparable quality, $_{gel}$$T_{g}$ is constant regardless of accelerator concentration in TTT (Time-Temperature-Transformation) diagram.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.11
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• pp.5930-5938
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• 2013

The sigmoid functionally graded mateiral(S-FGM) theory is reformulated using the nonlocal elatictiry of Erigen. The equation of equilibrium of the nonlocal elasticity are derived. This theory has ability to capture the both small scale effects and sigmoid function in terms of the volume fraction of the constituents for material properties through the plate thickness. Navier's method has been used to solve the governing equations for all edges simply supported boundary conditions. Numerical solutions of biaxial buckling of nano-scale plates are presented using this theory to illustrate the effects of nonlocal theory and power law index of sigmoid function on buckling load. The relations between nonlocal and local theories are discussed by numerical results. Further, effects of (i) power law index, (ii) length, (iii) nonlocal parameter, (iv) aspect ratio and (v) mode number on nondimensional biaxial buckling load are studied. To validate the present solutions, the reference solutions are discussed.

• International Journal of Highway Engineering
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• v.14 no.3
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• pp.49-58
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• 2012

In many countries including Korea, the design concept of pavement structure has been converted from empirical method to mechanisticempirical method since the advent of compaction control based on resilient modulus proposed by AASHTO in 1986. Studies of last decades indicates that the classical compaction control method based on relative compaction and plate bearing test(PBT) will necessarily move to the methods taking advantage of light falling weight deflectometer(LFWD) and dynamic cone penetrometer(DCP) in addition to PBT. In this study, the validity of resilient modulus prediction equation proposed by Korean Pavement Design Guide is verified by comparison with physical properties of subgrade soil and the results of structural analysis. In addition, correlational equations between elastic modulus measured by various field tests and resilient modulus estimated by empirical model are proposed. Finally, a field test-based compaction control procedure for subgrade is suggested by using proposed correlational equations.

• Journal of Korean Society of Steel Construction
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• v.21 no.3
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• pp.301-310
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• 2009

Steel has been widely used as a material in temporary structures. Corrosion attack often reduces the long-term durability of temporary steel members that are not protected from corrosion. In designing temporary steel structures, it is difficult to evaluate their long-term durability, since the thickness loss of steel members is not clear. In this study, laboratory and field exposure corrosion tests were performed on structural steel plate specimens, and the loss of thickness of specimens that were exposed to a subway construction site for 11 months and of specimens that were exposed to environments with controlled humidity and calcium chloride for six months were measured. Finally, a thickness loss equation was formulated based on the environmental conditions and the testing periods.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.380-383
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• 2006

The media transport system is used in a printer, a ATM(Automated Tellor Machine), and so on. The media transport system has many problems through miniaturization and rapid transportation of these machines. In the paper feeding mechanism, it is important to feed the sheet without jamming under any conditions. To avoid sheet jamming, first we need to predict the behavior of the sheet exactly. In this paper, the analysis of media behavior is based on J. Stolte's studies. In all of OA machines, a flexible beam or plate is pushed from the channel. The motion may be constrained by guides. This leads to a transient and geometrically nonlinear problem. The behavior of paper is simulated by dynamic elastica theory. The shape of guide is represented by parametric cubic curve. But J. Stolte's studies did not considered contact condition between sheet and guide. So Klarbring's Model. will be applied. And the analysis of flexible media has to include aerodynamic effect for more exact behavior analysis, because the flexible media can be deformed drastically by a little force. Therefore aerodynamic force must be applied to the governing equation. Lastly, the simulation of this model is performed, and the experiment is performed for verification of this model. The experimental results of low exit velocity are consistent with the simulation results, however experimental results of high exit velocity do not agree well with analytical results. The reason is that there may be other effects like nip Phenomena

• Applied Biological Chemistry
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• v.25 no.3
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• pp.111-118
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• 1982

A closed solar collector drying system by water exchange was evaluated for the drying of ginseng. The thermal efficiency of solar collector, drying efficiency, drying characteristics and product quality were investigated. The drying period was reduced by one-thirds in comparison with typical method. The maximum and minimum thermal efficiency of the solar collector during drying period were 14.42%, and 4.73%, respectively. The drying efficiency of solar collector and control system showed 28.34%, and 13.45%, respectively; net drying efficiency being 14.8%. The drying rate curve of red ginseng showed only falling rate period, and its equation was $Y=50.7023t.^{-0.4138}$ The brown color intensity of red ginseng was higher in solar collector drying system than in typical method, and reductivity by diphenyl picryl hydrazil solution in red ginseng extract showed similar result to brown color intensity.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.21 no.2
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• pp.151-156
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• 1985

In this paper, the plane stress fracture toughness of cold rolled 4.5mm thick SS41 steel plate was investigated for various crack ratios respectively in case of base metal, normalized and annealed heat-treated specimens using the method of J-integral. The specimen geometry used was double edge tension (DET) specimen. The experiments were performed on an Instron machine and all the crack lengths were measured by travelling microscope. The plane stress fracture toughness obtained by the method of Rice equation was J sub(1C)=22.8kgf/mm for the base metal, j sub(1C)-24.7kgf/mm for the normalized specimen and J sub(1C)=26.9 kgf/mm for the annealed. The J-integral computed at the limit load was found unsuitable for fracture toughness determination, because of large variation depending on the crack ratio.

• Transactions of the Korean Society of Automotive Engineers
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• v.7 no.8
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• pp.91-98
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• 1999

This paper describes the air flow characteristics inside the throttle valve. Tow-dimensional steady incompressible Navier-Strokes equation are solved numerically with embedding the conceopt of the artificial compressibility and adopting the Baldwin-Lomax turbulence model. With varying the valve opening angles(the Reynolds number )such as 15$^{\circ}$(5000) , 45$^{\circ}$(3000) , 75$^{\circ}$(7000) and 90$^{\circ}$(10000), respectively. tow cases, with a valve shaft and without one, are analysed. The pressure loss between the entrance and exit is severe at 15$^{\circ}$, 100 times as larger as that of 90$^{\circ}$ case, which also depends much on the existece of the valve shaft. The counter rotating vortices are formed over the valve plate with the shaft at only 75$^{\circ}$. They are smally and very large scale in front and back of the valve shaft , respectively. The velocity profiles of 15$^{\circ}$ and 90$^{\circ}$ at the exit are almost symmetric to the horizontal center line, however, the symmetricity is no longer maintained at 45$^{\circ}$ and 75$^{\circ}$ , and in addition, the flow at 75$^{\circ}$ is enforced a lot below center line. The pressure distribution on the walls is largely changed near the valve shaft, and its magnitude becomes great as the valve angle decreases.