• Proceedings of the KSME Conference
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• 2003.04a
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• pp.1030-1035
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• 2003

The nanoimprint lithography technology makes higher density of semiconductor device and larger capacity of storage media. In this technology the induced damage while detaching polymer pattern from mold should be minimized. In order to analyze the problem, the basic knowledge of adhesion between the polymer and the mold is required. In this study a contact experiment of polyisobutylene specimen with spherical steel tip and polyisobutylene bead tip was conducted using nano indenter. During the contact experiment with various loading rate under load control the contact behavior of viscoelastic material was measured, i.e., the load and displacement between the tip and the specimen were measured. The data was analyzed by HBK model to obtain the stress intensity factor of contact edge and the contact radius as a function of time. Also the adhesion energies between steel/polyisobutylene and polyisobutylene/polyisobutylene were obtained employing the analysis of the crack of viscoelastic material by Schapery.

• Structural Engineering and Mechanics
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• v.36 no.3
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• pp.343-361
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• 2010

The Discrete Element Method adopting particles for the domain discretization has recently been adopted in fracture studies of non-homogeneous continuous media such as concrete and rock. A model is proposed in which the reinforcement is modelled by 1D rigid-spring discrete elements. The rigid bars interact with the rigid circular particles that simulate the concrete through contact interfaces. The DEM enhanced model with reinforcement capabilities is evaluated using three point bending and four point bending tests on reinforced concrete beams without stirrups. Under three point bending, the model is shown to reproduce the expected final crack pattern, the crack propagation and the load displacement diagram. Under four point bending, the model is shown to match the experimental ultimate load, the size effect and the crack propagation and localization.

• Earthquakes and Structures
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• v.3 no.6
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• pp.783-804
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• 2012

Because of its large contribution to the environmental instability of the planet, the building industry will soon be subjected to a worldwide scrutiny. As a consequence, all professionals involved in the building industry will need to create a professional media in which their daily work adequately solves the technical issues involved in the conception, design and construction of concrete and steel buildings, and simultaneously convey care for the environment. This paper discusses, from the point of view of a structural engineer involved in earthquake-resistant design, some of the measures that can be taken to promote the consolidation of a building industry that is capable of actively contributing to the sustainable development of the world.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2006.04a
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• pp.365-372
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• 2006

A new meshfree formulation is developed for material discontinuity problems. A local interfacial jump function which is defined as hyperplane function is embedded in the meshless approximation and the approximation accurately models functions with jumps in the displacement and the derivative fields. Diffuse derivative technique copes with difficulty due to complexity of derivative computation of meshfree approximation. Collocation method with diffuse derivative accelerates computing speed for numerical solution. By solving inclusion and composite material problems, the robustness and effectiveness of the method are verified.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 1995.06a
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• pp.137-141
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• 1995

MASF is a kind of temporal filter proposed for noise reduction and temporal band limitation. MASF uses motion vectors to extract temporal information in spatial domain. Therefore, inaccurate motion information causes some distortions in MASF operation. Currently, bilinear interpolation after MBA(Block Matching Algorithm) is used for the motion estimation sheme of MASF. But, this method results in unreliable estimation when the object in image sequence has larger movement than the maximum displacement assumed in BMA or the input images are severely corrupted with noise. In order to solve this problem, we propose a hierarchical motion estimation algorithm for MASF. Experimental results show that the proposed method produces reliable output under large motion and noisy situations.

• Analytical Science and Technology
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• v.8 no.4
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• pp.649-654
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• 1995

The reactivity of superoxide ion($O{_2}^{-.}$) with halogenated substrates is investigated by cyclic voltammetry and rotated ring-disk electrode method in aprotic solvents. The more positive the reduction potential of the substituted nitrile, the more facile is nucleophilic displacement by $O{_2}^{-.}$. The reaction rates of halogenonitriles with $O{_2}^{-.}$ vary according to the leaving-group propensity of halide (Br>Cl>F). The relative reaction rates of other substituted nitriles are in the order of electron-withdrawing propensity of the substituent group (CN> $C(O)NH_2$ >Ph, $CH_2CN$). The reaction of $O{_2}^{-.}$ with dihalocarbons indicates that five-membered rings can be rapidly formed by the cyclization of substrate and $O{_2}^{-.}$, and the relative rates of cyclization depend on the number of methylenic carbons {$Br(CH_2)_nBr$, [n=1<2<3>4>5]}. Mechanisms are proposed for the reaction of $O{_2}^{-.}$ with halogenated substrates.

• 정보저장시스템학회:학술대회논문집
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• 2005.10a
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• pp.195-196
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• 2005

We report the new design of a miniature electromagnetic actuator for probe-based data storage with anti-vibration mechanism. The actuator consists of a media substrate, silicon frame, 2 pairs of magnets, a spacer, and a printed circuit board (PCB). The total area of the device is $11.2{\times}11.2 mm^2$ while the data recording area is $7.4{\times}7.4 mm^2$. A net momentum fee structure was included for high vibration resistance. The simulation shows that the lateral vibration can be reduced to below 100 nm for 1 G acceleration if the counter mass is adjusted with $1\%$ difference. The peak power for ${\pm}50 {\mu}m$ displacement is below 50 mW for a actuator with a resonance at 200 Hz.

• Geomechanics and Engineering
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• v.21 no.1
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• pp.85-93
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• 2020

In this article, the generalized thermoelastic theory with fractional derivative is presented to estimate the variation of temperature, the components of stress, the components of displacement and the changes in volume fraction field in two-dimensional porous media. Easily, the exact solutions in the Laplace domain are obtained. By using Laplace and Fourier transformations with the eigenvalues method, the physical quantities are obtained analytically. The numerical results for all the physical quantities considered are implemented and presented graphically. The results display that the present model with the fractional derivative is reduced to the Lord and Shulman (LS) and the classical dynamical coupled (CT) theories when the fractional parameter is equivalent to one and the delay time is equal to zero and respectively.

• Journal of the Korean Society of Safety
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• v.25 no.2
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• pp.7-11
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• 2010

Difficulties associated with full-scale pipe tests are rather obvious. That is, it is not only difficult to perform them but also very expensive and it requires lots of experience. And the process of the fracture test for the pipe specimen is very difficult and complicated. Because the pipe specimen, the test jig and the test equipment are very large and heavy, it requires lots of costs and times. In this study, to easily perform the fracture toughness test for a pipe specimen, load line displacement data was obtained using the image processing method.

• Proceedings of the Korea Water Resources Association Conference
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• 2002.05b
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• pp.1027-1033
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• 2002

The solute transport in a two-dimensional heterogeneous porous medium is numerically studied by using a random walk particle tracking (RWPT) method. Lognormally isotropic hydraulic conductivity fields are generated by using the turning band methods with mean zero and four different values of standard deviation. The numerical transport experiments are carried out to investigate the large time and spatial effects of the variable pore velocity field on solute plumes. The behavior of the solute plume through numerical simulations is presented in terms of longitudinal and transverse spatial moments: displacement of center-of-mass, plume spread variance and skewness coefficient. It was observed that the dispersive behavior of the solute plume is strongly affected by the degree of heterogeneity in the flow domain.