• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.274.1-274.1
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• 2013

We report the circumferential alignment of human aortic smooth muscle cells (HASMCs) in an orthogonally micropatterned circular microfluidic channel to form an in vivo-like smooth muscle cell layer. To realize a biomimetic smooth muscle cell layer which is aligned perpendicular to the axis of blood vessel, we first fabricated a half-circular polydimethylsiloxane (PDMS) microchannel by soft lithography using a convex PDMS mold. The orthogonally micro wrinkle patterns were generated inside the half-circular microchannel by stretching-releasing operation under UV irradiation. Upon UV treatment with uniaxial 40 % stretch of a PDMS substrate and releasing process, the microwrinkle patterns perpendicular to the axial direction of the circular microchannel were generated, which could guide the circumferential alignment of HASMCs successfully during cultivation. The analysis of orientation angle, shape index, and contractile protein marker expression indicates that the cultured HASMCs revealed the in vivo-like cell phenotype. Finally, we produced circular microchannels by bonding two half-circular microchannels, and cultured the HASMCs circumferentially with high alignment and viability for 5 days. These results are the first demonstration for constructing an in vivo-like 3D smooth muscle cell layer in the circular microfluidic channel which can provide novel bioassay platforms for in-depth study of HASMC biology and vascular function.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.22 no.1
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• pp.160-169
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• 1998

The purpose of this study for the prediction of fatigue crack propagation behavior, Stress Intensity Factor(F) of round bar with 3-Dimensional half circular, semi-elliptical icro surface crack under rotary bending stress for the variable aspect, size, rotation angle was analyzed by Boundary Element Method (BEM). It is predicted that behavior of crack growth is half circular or circular crack (b/a.geq.1) and propagate to b/a.leq.0.85.

• 전기의세계
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• v.18 no.4
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• pp.7-15
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• 1969

In this method the condenser excite winding has the phase angle of 90 electrical degree, with the load winding in stator. The condenser excite wing is connected with the condenser while the load winding is with the full rectifer. Direct and quardrature axis components of rotating field winding are composed, of balanced two phase winding, and each one of them is connected with half wave rectifiers. Initically, small amount of lead current can be induced at the condenser excite winding by residual magnetism of rotor. The induced lead current forces the rotating field winding to be excited by synchronous alternating magnetic field. The speed electromotive force, there for, induced in rotating field winding shall electro magnetize the rotating field pole by rotating half wave rectifiers. In the case of the charging generator directly coupled with engines at the operation of wide range speed, the generated region, such as vehicles, aircraft, ships etc, is occured. In conclusion, we can take the advantage of, omitting of voltage regurator and current limiter for charging load and reducing the consumption of fuel using the generated region which can be devided in to Impossible generated region, Generated region, and suspension generated region.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.10
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• pp.1832-1837
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• 2011

The fault current has increased due to the large power demand in power distribution system and network distribution system. To protect the power system effectively from the increased fault current, the superconducting fault current limiter (SFCL) has been notified. However, the conventional SFCL has some problems such as cost, operation, recovery, loss. To solve some problems, the hybrid superconducting fault current limiter using the fast switch was proposed. However, hybrid SFCL also has a problem that is protection coordination in power distribution system with hybrid SFCL. In this paper, the fault current limiting characteristics of hybrid SFCL with first half cycle non-limiting operation according to the fault angle, the resistance of superconducting element, and the magnitude of Current Limit Resistor (CLR) which are the components of hybrid SFCL were analyzed through the experiments.

• Korean Journal of Optics and Photonics
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• v.11 no.4
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• pp.279-288
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• 2000

The variations of output energy due to tilt output coupler for different types of pulsed Nd:YAG laser resonators were compared by measuring FWHM (full width at half maximum) which means the width of angle displacement where maximum output energy decreases to half value. We proposed a new configuration of pulsed solid-state laser resonator which had high FWHM for tilting of output coupler and which was little sensitive for tilting of rear optics. We proved that our laser resonator had high alignment stability using ABeD ray matrix method because the ray matrix of such a resonator corresponded to unit matrix. atrix.

• Solar Energy
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• v.9 no.1
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• pp.43-52
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• 1989

Heat transfer rate and heat flux from the condenser with internally triangular fins rotating heat pipe has been numerically studied by finite element method. The results of numerical and P.J. Martos' experimental showed good agreement and it was able to predict to the performance of a rotating heat pipe. By increasing fin half angle or fin height, heat transfer rate from condenser was increased slightly but heat flux was decreased. By increasing condenser radius or r.p.m. of rotating heat pipe, heat transfer rate and heat flux was increased rapidly. Heat transfer rate was rapidly increased with increasing fin numbers in case of few fm numbers but slowly increased at many fin numbers. So the optimum fin numbers were a half of maximum fin numbers which was able to install in the condenser of a rotating heat pipe.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1998.10a
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• pp.463-470
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• 1998

The boundary/finite element analysis for the seismic wave amplifications due to nonhomogeneous alluvial deposits was performed in this study. For numerical analysis, the homogeneous linear elastic soil half-space was modeled by using the 3-node isoparametric boundary elements and the inhomogeneous alluvial deposit was modeled by using the 8-node isoparametric finite elements. The two elements at interface were coupled together by the equilibrium condition of the tractions and the compatibility condition of the displacements. As a prarmetric variable, the incident angle and the dimensionsless frequency of the SH, P and SV-waves and the shear wave velocity ratio and the mass density ratio between the half-space and the alluvial deposit were selected.

• Structural Engineering and Mechanics
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• v.66 no.1
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• pp.113-124
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• 2018

In the present paper, we have considered a layered medium of two semi-infinite nonlocal elastic solids with intermediate transversely isotropic magnetothermoelastic solid. The intermediate slab is of uniform thickness with the effects of two temperature, rotation and Hall current and with and without energy dissipation. A plane longitudinal or transverse wave propagating through one of the nonlocal elastic solid half spaces, is made incident upon transversely isotropic slab and it results into various reflected and refracted waves. The amplitude ratios of various reflected and refracted waves are obtained by using appropriate boundary conditions. The effect of nonlocal parameter on the variation of various amplitude ratios with angle of incidence are depicted graphically. Some cases of interest are also deduced.

• Korean Journal of Optics and Photonics
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• v.2 no.3
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• pp.127-132
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• 1991

We have obtained the analytic solutions of the four spherical mirror system free from the Seidel third order aberratios which are spherical aberration, coma, astigmatism, and distortion, Vignetting. Petzval field curvature, and optical properties according to the design parameters are numerically investigated and optimized. The numerical aperture of this system is 0.2 and the half field angle is $1.5^{\circ}$.

• Earthquakes and Structures
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• v.18 no.6
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• pp.743-752
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• 2020

The phenomenon of reflection and transmission of plane waves at an interface between fluid half space and orthotropic piezothermoelastic solid half-space with two-temperature has been investigated. Energy ratios of various reflected and transmitted waves are computed with the use of amplitude ratios. The law of conservation of energy across the interface has been justified. It is found that the energy ratios are the functions of angle of incidence, frequency of independent wave and depend on the different piezothermoelastic material. A piezothermoelastic material has been considered which is in welded contact with water. Variations of energy ratios corresponding to the reflected waves and transmitted waves are computed and shown graphically for the two different models. A particular reduced case of interest is also discussed.