• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.2 no.4
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• pp.303-315
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• 1990

Uniformity of velocity is quite important design points of a vertical laminar flow type clean room. In the present paper, flows in a room with a bottom pannel are numerically simulated by using a low-Reynolds number $k-{\epsilon}$ model, and a new flow model of the pannel are suggested. Resistance coefficient of the pannel and size of the exhaust channel show considerable effects on flow pattern and uniformity of flow on the bottom. Reflection coefficient also has important roles. A possibility to obtain the uniform and unidirectional flow is tested by adjusting the distribution of resistance coefficient of the pannel. Such a numerical simulation of the flow will be a good method to get optimun design parameters.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.8
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• pp.1308-1316
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• 2001

A hybrid type master system is proposed to take the advantage of the link mechanism and magnetic levitation mechanism without using a force sensor. Two different types of electromagnetic actuators, moving coil type and moving magnet types are used to drive the master system which is capable of 4-DOF actuation. It is designed that the rotation motions about x-y axis are decoupled and the whole system is represented by simple dynamic equations. The force reflection is achieved by using the simple relation between the force and applied current and position. The simulation and experimental results are presented to show its performance.

• Water for future
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• v.19 no.3
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• pp.259-266
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• 1986

A numerical study of the process of wave deformation, such as reflection and transmission coefficients and wave forms with bottom change was carried out by Boundary Element Method using linear elements. It is assumed that the incident wave is normal and oblique to the bottom and the wave may be described by linear theory The accuracy of the computational scheme is investigated by comparing the results of other researchers in the following several cases. (1) Simple and sloping stepped bottom geometry (2) Submerged breakater type bottom geometry (3) Trench type bottom geometry

• Journal of Periodontal and Implant Science
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• v.28 no.2
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• pp.371-376
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• 1998

This study presents an evaluation of the effectiveness of nonsurgical subgingival scaling and root planing related to initial pocket depth, type of teeth, and individual root surfaces. A total of 110 teeth designated for periodontal surgery in 67 patients with marginal periodontitis were selected and received thorough scaling and root planing with standard rigid Gracey curettes. After a healing period of 4 to 8 weeks, residual calculus was assessed at the time of periodontal surgery following the reflection of mucoperiosteal flap. The results demonstrated a high correlation between the percentage of residual calculus and initial pocket depth. It was further noted that tooth type and involved root surface also influenced the rate of calculus remnant. The results of this study suggest that complete removal of subgingival calculus utilizing conventional instrumentation via closed approach is rare.

• Korean Institute of Interior Design Journal
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• v.15 no.6 s.59
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• pp.120-130
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• 2006

This study is about objectified spatial composition. The Interior Design field has grown and established its major trends dependent upon other related field of study. With this perspective in mind, esthetics on Interior Design has to be treated in similar manner. In modem architects or fine artists have defined the terminology 'objectification' theoretical principle where by unable to distinguish between 'object's type' and 'objects', Presently, the term 'objectified' became a trend word. In order to confront misconception of the idea of 'objectification', some people define as reflection of this complex society. There are five types in expression of objectified spatial composition in Interior Design. Which are free form spatial composition through artistry of artists, fantastic spatial composition by polysemous collision, symbolic spatial composition from the metaphorical of form, aggregate spatial composition by geometric collision and geometric superimposition, and cultural spatial composition. Therefore, this study aims to help understanding of tendency in various space expressions in Interior Design through searching how to express type of objectified spatial composition in Interior Design from 2000 through 2005.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.55 no.5
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• pp.267-271
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• 2006

A polymeric waveguide-type wavelength filter based on a Bragg grating has been proposed and fabricated using the simple nanoimpring technique, for the first time to our knowledge. An ultraviolet transparent stamp with the single-mode waveguide pattern incorporating a surface-relief-type Bragg grating was specially designed selective dry-etching process. Using this stamp, the device fabrication was substantially involving just a single-step process of imprint followed by polymer spin-coating. The achieved maximum reflection was higher than 25 dB at the center wavelength of 1569 nm. And the 3-dB bandwidth was 0.8 nm for the device length of 1.5 cm.

• Steel and Composite Structures
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• v.27 no.4
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• pp.439-451
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• 2018

In the present investigation, a plane P (longitudinal) wave is made incident upon a transversely isotropic magnetothermoelastic solid slab of uniform thickness, interposed between two different semi-infinite viscoelastic solids. The transversely isotropic magnetothermoelastic sandwiched layer is homogeneous with combined effects of two temperature, rotation and Hall current in the context of GN Type-II and Type-III (1993) theory of thermoelasticity. The amplitude ratios of various reflected and refracted waves are obtained by using appropriate boundary conditions. The effect of energy dissipation on various amplitude ratios of longitudinal wave with angle of incidence are depicted graphically. Some cases of interest are also deduced from the present investigation.

• Korean Journal of Metals and Materials
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• v.50 no.5
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• pp.389-393
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• 2012

Improvement in microwave absorbance has been investigated by insertion of a periodic air cavity in rubber composites filled with magnetic powders. A mixture of $Co_2Z$ hexagonal ferrite and Fe powders were used as the absorbent fillers in silicone rubber matrix. The complex permeability and complex permittivity of the magnetic composites were measured by reflection/transmission technique. In the grid-type magnetic absorbers, the equivalent permeability (${\mu}_{eq}$) and permittivity (${\varepsilon}_{eq}$) are calculated as a function of air volume rate (K) on the basis of effective medium theory. Reduction in the material parameters (especially, dielectric permittivity and magnetic loss) has been estimated with the increase of K. Plotting the ${\mu}_{eq}$ and ${\varepsilon}_{eq}$ on the solution map of wave-impedance matching, wide bandwidth microwave absorbance has been predicted in the magnetic composites with an optimum value of K.

• Journal of Ship and Ocean Technology
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• v.7 no.1
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• pp.13-18
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• 2003

The control performances for active re-reflecting wave control suggested in the previous paper have been verified in cases of regular and irregular waves in a real two dimensional wave basin. For regular waves, the control performances are investigated in terms of reflection coefficients, expected amplitudes of propagating waves and wave absorbing capabilities after cessation of wave generation, compared with those of no-control cases. For irregular waves similar verification procedures were adopted. Though there are certain constraints due to the geometrical non-linearity of wave maker and certain nonlinear characteristics due to the near field and gravity waves these experiments show that the control logic could be useful in realizing re-reflecting wave control in conditions of real wave basin.

• International Journal of Korean Welding Society
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• v.1 no.2
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• pp.45-50
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• 2001

This paper presents application of neutron diffraction technique to the measurement of residual stresses in the T-type 20 m thick welded stainless steel plates(100$\times$50 $mm^2$ and 50$\times$50 $mm^2$). The High Resolution Powder Diffractormeter of the Korea Atomic Research Institute was utilized in the measurement. The power of nuclear reactor was 24 MWt and the measured reflection in the 220 plane (2$\theta$）was $92.66^{\circ}$. Poisson ratio of 0.265 and elastic constant of 211 GPa were applied to the calculation of stresses and strains. Three directional components such as normal, transverse, and longitudinal stresses were measured. The results showed that three components were tensile and became compressive along the y axis in the zone away from the welded center. The compressive stresses became tensile in the zone away from the center line of x axis. This may be due to the balance effect caused by the net stress to keep the specimen shape flat.