• Journal of the Korean Society for Precision Engineering
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• v.14 no.6
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• pp.44-51
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• 1997

Crinding of stainless steel, aluminium alloy, copper alloy, and titanium alloy are difficult to obtain high quality finish, because they have the mechanical properties such as low hardness, high toughness. The low hardness and the high toughness result in the loading of wheel and the poor surface finish. In order to perform the grinding operations for these sorts of materials easily, the discontinuous grinding wheel wiht multi-porous grooves has been newly developed. The multi-porous grooves inthe discontinuous grinding wheel were formed during grinding wheel manufacturing process. In this paper, discontinuous grinding wheels having intermittent ratio 0.66, 0.81 and number of grooves 18,32 have been manufactured and grinding surface characteristics of these grinding wheels for SUS304 have been analyzed. Discontinuous grinding temperature according to intermittent ratiohas been also estimated by simulation. The discontinuous grinding wheels increase the grinding performance considerably. It is desirable to use the discontinuous grinding wheel in grinding the materials with high efficiency and accuracy.

• Ocean Systems Engineering
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• v.5 no.4
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• pp.319-329
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• 2015

Submerged breakwaters are used to prevent shore line erosion and sediment transportation. One of their advantages is low visual impact. In this paper, the effects of discontinuous submerged breakwaters over water surface elevation was numerically studied considering the extended Boussinesq equations as governing equations using MIKE21 software. The result of discontinuous breakwater was compared with a beach without breakwater. The results showed that the gap dramatically effects on surface elevation from shore line to offshore. It is also evident from results that with approaching the center of the gap, fluctuation of surface elevation is generated. It is because of passing longshore currents towards offshore through the gap which leads to an increase in sediment transportation rate. Nevertheless, transferring water mass from breakwater gap results in powerful rip currents leading to high changes on longshore wave profile.

• Journal of the Korean Society for Precision Engineering
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• v.13 no.8
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• pp.52-59
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• 1996

Conventionally, grinding of stainless steel, aluminium ally, copper alloy, and titanum alloy are difficult to obtain the high quality finish, because they have the mechanical properties such as low hardness, high toughness which result in the loading of wheel and the poor surface finish. Inorder to perform the grinding operations for these sorts of materials easily, the discontinuous grinding wheel with multi-porous grooves has newly been developed. The multi-porous grooves were formed during wheel production. This discontinous grinding wheel increases the grinding performance. It is desirable to use the discontinuous grinding wheel when grinding materials wiht high efficiency and accuracy which is impossible by conventional wheels. In this paper, the constructing and manufacturing method of grinding wheel with multi-proous grooves are explained, and the grinding charateristics of discontinuous grinding wheel are also illustrate.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1996.03a
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• pp.108-113
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• 1996

Conventionally, grinding of stainless steel, aluminium alloy, copper alloy, and titanum alloy is difficult due to the mechanical properties such as low hardness, high toughness which result in the loading of wheel and the poor surface finish. In order to grind this sort of materials easily, discontinuous grinding wheel with multi-porous grooves was newly developed. The multi-porous grooves were formed during wheel production. This discontinuous grinding wheel drastically increases the grinding performance. It is desirable to use the discontinuous grinding wheel when grinding materials with high efficiency and accuracy which is impossible by conventional wheels. In this paper, the construction and manufacturing method of grinding wheel with multi-porous grooves are explained. The grinding charateristics of discontinuous grinding wheel was also illustrated.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.04a
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• pp.857-861
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• 1997

In discontinuous wheel grinding, temperature is different form conventional grinding. The characteristics of discontinuous grinding with respect to various slotted wheel were compared with those of general grinding. Thermal conditions vary with intermittent ratio, direction of fluid supply for discontinous wheel. According to three direction of grinding fluid supply and intermittent ratio,temperature and surface roughness were analyzed.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.127.4-127
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• 2001

Inspection and shape measurement of three-dimensional objects are widely needed in industries for quality monitoring and control. A number of visual or optical technologies have been successfully applied to measure three dimensional surfaces. Especially, the shape measurement using an interferometric principle becomes a successful methodology. However, those conventional interferometric methods to measure surface profile have an inherent shortcoming, namely 2∏ ambiguity problem. The problem inevitably happens when the object to be measured has discontinuous shape due to the repetition of interferometric signal with phase period of 2∏. Therefore, in this paper, we choose as a shape measuring method, ...

• Journal of the Korean Geotechnical Society
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• v.25 no.5
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• pp.65-73
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• 2009

Large scale model tests and numerical analyses are performed to investigate the stress distribution of pillar due to surface loading nearby two-arch tunnel which is constructed in the regularly jointed rocks. It is observed that the influence of discontinuities on the stress distribution in the discontinuous rock mass and the underground stresses induced by surface loading are greater than those of linear elastic theory. Especially, lines of equal stresses are developed to the direction of inclination according to the inclined grade. In cases of discontinuities imbedded in parallel with or vertical to the ground, the pressure bulbs are formed symmetrically, however, the inclined ones result in stress distribution in parallel with and vertical to the planes of discontinuities. Results indicated that stress distribution is seriously affected by the angle of discontinuity. When stresses propagating to the pillar need to be estimated, relative location of surface loading, grade of discontinuous plane, and location of two-arch tunnel should be carefully considered.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1997.04a
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• pp.701-708
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• 1997

A direct boundary element method(DBEM) is developed for thin bodies whose surfaces are rigid or compliant. Th eHelmholtz integral equation and its normal derivative integral equation are adopted simultaneously to calculate the pressure on both sides of the thin body, instead of the jump values across it, to account for the different surface conditions of each side. Unlike the usual assumption, the normal velocity is assumed to be discontinuous across the thin body. In this approach, only the neutral surface of the thin body has to be discontinuous across the thin body. In this approach, only the neural surface of the thin body has to be discretized. The method is validated by comparison with analytic and/or numerical results for acoustic scattering and radiation from several surface conditions of the thin body; the surfaces are rigid when stationary or vibrating, and part of the interior surface is lined with a sound-absorbing material.

• Journal of the Korea Institute of Military Science and Technology
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• v.22 no.5
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• pp.607-615
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• 2019

In this paper, the electromagnetic effects on the discontinuity structures of the frequency selective radome in manufacturing process based on the X-band were analyzed. In order to fabricate a curved radome using a planar frequency selective surface structure, it is assumed that gaps, slanted gaps, pattern damage, and pattern misalignment between FSS patterns, which are discontinuous elements that can occur at the joint surface of the FSS panel. FSS specimens including continuous elements were fabricated and the frequency transmission characteristics were measured in a free space measurement environment. From the measurement results, resonance frequency shift, transmission performance degradation, and bandwidth variations were found to be the largest when the damaged pattern was bonded to the junction of FSS panels.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.04a
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• pp.353-358
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• 1998

The strain localization is a discontinuous phenomenon that addresses the formation of jumps of the field variables across a singularity surface. It has become widely accepted that the localization may occur as the result of discontinuous bifurcation which corresponds to the loss of ellipticity of the governing differential equations for elasto-plastic continua. In this paper, condition for strain localization in concrete based on bifurcation theory is studied and localization tensor analysis algorithm is employed to determine the directions of localization of deformations in concrete. By applying a plasticity model of concrete into the algorithm, localization analysis is performed concrete under uniaxial tension, pure shear and uniaxial compression.