• Journal of Ocean Engineering and Technology
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• v.17 no.5 s.54
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• pp.25-31
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• 2003

Numerical experiments have been conducted using the nonlinear combined refraction-diffraction model, in order to analyze the generation characteristics of stem wave, which is formed by the interaction between vertical structure and the oblique incident waves. The results of stem wave are discussed through the stem wave height distribution along/normal vertical structure, under the wide range of incident wave conditions-wave heights, periods, depths, and angles. Under the same wave height and period, the larger the incident wave angle, the higher the stem wave heights. According to the results of wave height distribution, in front of vertical structure, the maximum of stern wave heights occurs in the location bordering the vertical wall. Furthermore, the most significant result is that stem waves occur under the incident angles between $0^{\circ}\;and\;30^{\circ}$, and the stem wave height ratio has the maximum value, which is approximately 1.85 times the incident wave height when the incident wave angle becomes $23^{\circ}$.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.34 no.2
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• pp.27-36
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• 2022

The large uprush could be occurred when the waves hit the coastal structure and this uprush by wave could make the overtopping. The downfall of the wave overtopping water over the structure brought about the vertical impact loads. The vertical impact loads should be evaluated in order to design the pavement behind the crown wall however these loads were still unclear. In this study, the hydraulic model tests for the downfall impact loads by wave overtopping were performed and the various conditions were applied to the tests. The effect of the incident wave condition, the freeboard, the armour crest height and the height of the parapet were investigated. The test results showed that the parapet on the crown wall could reduce the wave overtopping however the inclusion of parapet could lead to the increased downfall wave pressures behind the crown wall. The empirical formulae were proposed for evaluating the maximum downfall pressures behind the crown wall of rubble mound structure.

• Journal of the Korean Society of Safety
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• v.19 no.3 s.67
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• pp.108-117
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• 2004

Dynamic analysis method is Presented for analyzing rectangular liquid storage structures excited by horizontal and vertical ground motions. The irrotational motion of invicid and incompressible ideal fluid in rigid rectangular liquid storage structures subjected to horizontal and vertical ground motions and the motion of fluid induced by structural deformation are expressed by analytic solutions. Analysis methods are obtained by applying analytic solutions of the fluid motion to finite element equation of the structural motion. The fluid-structure interaction effect is reflected into the coupled equation as added fluid mass matrix. The free surface sloshing motion, hydrodynamic pressure acting on the wall and structural behavior due to horizontal and vertical ground motions are obtained by the presented method.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2009.11a
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• pp.35-39
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• 2009

Recently, the flat-plate structure is widely used because it has many advantages such as reduction of story height, long span etc than the RC rahmen structure. Furthermore, application of the flat-plate is on the increase because of flexible plan unlike wall structure. Long span have been at a disadvantage for vibration serviceability evaluation, however studies about vertical direction vibration of flat-plate structure has not been carried out. This study analysis the characteristics according to slab structure to make an experiment on vibration and floor impact noise for the flat-plate structure in construction performance laboratory in Kolon E&C R&D center, the flat-plate structure applied to the post-tension method, and the wall structure in apartment houses.

• 한국전산유체공학회:학술대회논문집
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• 2008.03b
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• pp.671-674
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• 2008

We investigate the slippage effect in a micro-channel depending on the surface characteristics; hydrophilic, hydrophobic, and super-hydrophobic wettabilities. The micro-scale grooves are fabricated on the vertical wall to make the super-hydrophobic surfaces, which enable us visualize the flow fields near walls and directly measure the slip length. Velocity profiles are measured using micro-particle image velocimetry (Micro-PIV) and compared those in the hydrophilic glass, hydrophobic PDMS, and super-hydrophobic PDMS micro-channels. To directly measure the velocity in the super-hydrophobic micro-channel, the transverse groove structures are fabricated on the vertical wall in the micro-channel. The velocity profile near the wall shows larger slip length and, if the groove structure is high and wide, the liquid meniscus forms curves into the valley so that the wavy flow is created after the grooves.

• Journal of the Microelectronics and Packaging Society
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• v.22 no.4
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• pp.71-76
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• 2015

Recently, light emitting diodes (LEDs) have been studied to improve their efficiencies for the uses in various fields. Particularly in the aspect of chip structure, via hole type vertical LED chip is developed for improvement of light output power, and heat dissipations. However, current vertical type LEDs have still drawback, which is current concentration around the n-contact holes. In this research, to solve this phenomenon, we introduced isolation layer under n-contact electrodes. With this sub-electrode, even though the active area was decreased by about 2.7% compared with conventional via-hole type vertical LED, we could decrease the forward voltage by 0.2 V and wall-plug efficiency was improved approximately 4.2%. This is owing to uniform current flow through the area of n-contact.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.55-56
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• 2006

This paper describes a new concept of the robot that can climb on the vertical plane. The engineering design problem of the main structure is presented and the experimental results regarding a new mechanism of climbing on the vertical wall are discussed. The locomotive motion of the robot is realized by using a series chain of two caterpillar wheels on which 24-suction pads are installed. White each caterpillar wheel rotates on the vertical plane surface, the vacuum pads are activated in sequence based on the sequential opening by specially designed mechanical valves. The detail design feature of the valve is also described in this paper. The overall size of the robot is around 460 mm in width and length, respectively, and 200 mm in height. Its mass is slightly over 14 kg. The main mechanical structure of the robot consists of driving motors, vacuum caterpillar system, steering part, vacuum pump and battery. The performance of the robot is verified on the vertical wall.

• Journal of the Korean Professional Engineers Association
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• v.42 no.4
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• pp.55-61
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• 2009

Retaining wall is a structure to stabilize the land slope as vertical retaining wall have constructed to make efficiency use of downtown area. Recently to commune with nature and refine a apartment and structure, natural friendly relations for retaining walls are tried to construct. The surface of the concrete walls are weave in various figures and colours, and in some places plant a shrub. Laying a landscape stone which have disclose a plane nature one means keeping up the natural slope, constructively safely set a anchor in front side and rear side wall between the natural stone, plant shrub or ground coverings to give shape into a rock. Natural stone is exposed of surface and planting the gardening, to be a type of natural friendly relations however that will be recycled. The size of blasted nature stone which is irregular become more natural type of one.

• Structural Engineering and Mechanics
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• v.77 no.1
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• pp.37-46
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• 2021

In this study, a method for free vibration analysis of wall-frame systems built on weak soil is proposed. In the development of the method, the wall-frame system that constitutes the superstructure was modeled as flexural-shear beam. In the study, it is accepted that the soil layers are isotropic, homogeneous and elastic, and the waves are only vertical propagating shear waves. Based on this assumption, the soil layer below is modeled as an equivalent shear beam. Then the differential equation system that represented the behavior of the whole system was written for both regions in a separate way. Natural periods were obtained by solving the differential equations by employing boundary conditions. At the end of the study, two examples were solved and the suitability of the proposed method to the Finite Element Method was evaluated.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2005.10a
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• pp.135-140
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• 2005

There are cofferdam and watertight wall to prevent of circulation or pollution during building of ocean structures like a dam and bridge in the harbors area and the sea. Inflow fluid and base of structure is important thing as one of the structural design factors for this interception wall like a cofferdam and watertight wall. In this study, it is revealed that at least 500 instantaneous velocity field data are required for ensemble average to get reliable turbulence statistics. The turbulent shear flow around a surface-mounted vertical wall was investigated by using the two-frame PIV(CACTUS 3.1) system and Mean velocity distributions have also been measured in the whole flow field.