• 제어로봇시스템학회:학술대회논문집
• /
• 2005.06a
• /
• pp.2455-2458
• /
• 2005

In this paper, we analyzed the effect of a training system for improving equilibrium sense. This training system consists of an unstable platform, a force plate, a computer, and training programs. Using the system with training programs, we performed various experiments to train the equilibrium sense of fifteen subjects. To evaluate the effect of the training system, we measured the time a subject maintains a focus, the moving time to the target, and the absolute deviation of the trace. We analyzed these parameters obtained before and after the training using paired-samples T-test. The results showed that the subjects experienced a distinctive enhancement of their equilibrium senses through the training using our system.

• Journal of the Korean Ceramic Society
• /
• v.31 no.7
• /
• pp.715-722
• /
• 1994

Off-axis supttering using shielder was used to efficiently prevent negative oxygen ions from resputtering deposited films. In this method, the substrate was located vertically to the target and shielded by the semicircled steel plate. By using this method, the resputtering could be reduced, and 2223 high-Tc phase could be formed at the lower substrate temperature and in the broader temperature region. As increasing the substrate temperature, 2212, 2223, 2212 superconducting phases were formed by turns. 2223 phase was formed above 2$\times$10-2 torr, and 2212 phase was formed above 4$\times$10-2 torr.

• Proceedings of the Korea Concrete Institute Conference
• /
• 1995.10a
• /
• pp.293-298
• /
• 1995

This study experimentally evaluate the bonding performance of repair and strengthening materials. It is very important problem to justify bonding properties between repair and strengthening materials and old concrete. Many previous research and investigation showed that bonding strength of reinforcing materials determines the strengthening effect and the durability of repair work. Therefore, menifestation of bonding properties and the improvement of bonding performance of repair and strengthening materials are very important. In order to improve the perforamnce of repair work, it needs to investigate the behavior of bonding materials, such as stress distribution along the bonding area and the long term performance of the material. The target repair methods are steel plate addition technique and repair mortar method, and the test parameters studied in this paper include epoxy thickness, bonding surface texture, and bonding area.

• Bulletin of Food Technology
• /
• v.18 no.1
• /
• pp.91-98
• /
• 2005

Aims: As a preliminary experiment on new sanitizer delivery tools, the efficacy of aerosolizedsanitizer on foodborne pathogens was investigated in larger model chamber system.Methods: Peroxyacetic acid and hydrogen peroxide were aerosolized in a model system againstartificially inoculated target microorganisms on laboratory media. Cultures of 4 different foodborne pathogens were inoculated and affixed onto 3 different heights (bottom, wall, and ceiling), and 3different orientations (face-down, vertical, and face-down) inside a commercial semi-trailer cabinet(14.6 x 2.6 x 2.8 m). Sanitizer was aerosolized into 2 m droplet size fog and treated for 1 h atambient temperature.Results: Populations of Bacillus cereus, Listeria innocua, Staphylococcus aureus, and Salmonellatyphimurium were reduced by an average of 3.09, 7.69, 6.93 and 8.18 log units per plate, respectively.Interestingly, L. innocua, Staph. aureus, and Salm. typhimurium showed statistically not different (P$\leq$ 0.05) reduction patterns relative to height and orientation that were never expected in a sprayingsystemConclusion and significance: Aerosolized sanitizers diffuse like gaseous sanitizers, so it has greatpotential for use in commercial applications.

• Journal of Advanced Marine Engineering and Technology
• /
• v.27 no.2
• /
• pp.229-237
• /
• 2003

The flow and heat transfer characteristics at the surface of two-dimensional protruding heated blocks using confined impingement multiple slot jets were computationally investigated Numerical predictions were made for round-edged nozzles at several nozzle-to-target plate spacings and jet-to-jet distances, with turbulent jet Reynolds numbers ranging from 2000 to 7800. The commercial finite-volume code FLUENT was used to solve the heat transfer characteristics and flow fields using a RNG $\textsc{k}-\varepsilon$ model. The computed heat transfer characteristics at the surface of heated blocks were in good qualitative agreement with previous experimental data The results of heat transfer characteristics on the surface of protruding heated blocks are important considerations in electronics Packaging design.

• Proceedings of the KSME Conference
• /
• 2000.11b
• /
• pp.603-608
• /
• 2000

The characteristics of laminar and turbulent slot impinging jet flows are examined using segregated FEM with SUPG. Turbulent flows are modeled using $Wilcox^{(1)}$ $k-\;{\omega}$ turbulence model. The results are validated by comparing with velocity field of the existing experimental data. The distance of the target plate from the nozzle varies between 2, 4 and 5 times the slot jet width. Present study shows that the $k-\;{\omega}$ model gives results which agree well with the existing experimental data. In turbulence flows, the velocity profile of present calculation is more accurate than the existing numerical calculations. In laminar flows, We found tertiary vortex which was not found in the previous numerical study by M. $chen^{(6)}$ et al due to the numerical difference.

• Journal of Korean Association for Spatial Structures
• /
• v.17 no.4
• /
• pp.35-42
• /
• 2017

This study develops a new hybrid passive energy dissipation device for seismic rehabilitation of an existing structure. The device is composed of a friction damper combined with a steel plate with vertical slits as a hysteretic damper. Analytical model is developed for the device, and the capacity of the hybrid device to satisfy a given target performance is determined based on the ASCE/SEI 7-10 process. The effect of the device is verified by nonlinear dynamic analyses using seven earthquake records. The analysis results show that the dissipated inelastic energy is concentrated on the hybrid damper and the maximum interstory drift of the SMRF with damping system satisfies the requirement of the current code.

• Structural Monitoring and Maintenance
• /
• v.1 no.3
• /
• pp.339-356
• /
• 2014

This study has been motivated to evaluate the practicality of numerical simulation of impedance monitoring for damage detection in steel column connection. In order to achieve the objective, the following approaches are implemented. Firstly, the theory of electro-mechanical (E/M) impedance responses and impedance-based damage monitoring method are outlined. Secondly, the feasibility of numerical simulation of impedance monitoring is verified for several pre-published experimental examples on steel beams, cracked aluminum beams, and aluminum round plates. Undamaged and damaged steel and aluminum beams are simulated to compare to experimental impedance responses. An aluminum round plate with PZT patch in center is simulated to investigate sensitive range of impedance responses. Finally, numerical simulation of the impedance-based damage monitoring is performed for a steel column connection in which connection bolts are damaged. From the numerical simulation test, the applicability of the impedance-based monitoring to the target steel column connection can be evaluated.

• 한국전산유체공학회:학술대회논문집
• /
• 1997.10a
• /
• pp.49-54
• /
• 1997

Rice's monotone streamline upwind finite element method, which was proposed to treat convection-dominated flows, is applied to the linear triangular element. An alignment technique of unstructured grids with given velocity fields is used to prevent the interpolation error produced in evaluating the convection term in the upwind method. The alignment of grids is accomplished by optimizing a target function defined with the inner-product of a properly chosen side vector in the element with the velocity field. Two pure advection problems are considered to demonstrate the superiorities of the present approach in solving the convection-dominated flow on the unstructured grid. Solutions obtained with aligned grids are much closer to the exact solutions than those with initial regular grids. The capability of the present approach in predicting the appearance of the secondary vortex in the laminar confined jet impingement is shown by comparing streamlines to those produced by SIMPLE on a highly stretched grid toward the impingement plate.

• Journal of Welding and Joining
• /
• v.32 no.2
• /
• pp.43-47
• /
• 2014

Famous artificial neural network (ANN) is applied to predict proper process window of arc welding. Target weldment is variously combined lap joint fillet welding of automotive steel plates. ANN's system variable such as number of hidden layers, perceptrons and transfer function are carefully selected through case by case test. Input variables are welding condition and steel plate combination, for example, welding machine type, shield gas composition, current, speed and strength, thickness of base material. The number of each input variable referred in welding experiment is counted and provided to make it possible to presume the qualitative precision and limit of prediction. One of experimental process windows is excluded for predictability estimation and the rest are applied for neural network training. As expected from basic ANN theory, experimental condition composed of frequently referred input variables showed relatively more precise prediction while rarely referred set showed poorer result. As conclusion, application of ANN to arc welding process window derivation showed comparatively practical feasibility while it still needs more training for higher precision.