• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2018.11a
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• pp.210-211
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• 2018

In general, the dam break problem is demonstrated to simulate open-channel disturbance due to large violent waves. These days, the large violent waves at shore and coastline can be seen frequently such like tsunami. The conventional computational fluid dynamics program based on Grid system, can be used to simulate this problem with large deformation of free surface in the restricted condition due to its limitation. The particle method based on fully Lagrangian approach is able to simulate large deformation of free surface by tracking each particles. In this study, the simulation of disturbance of mobile-bed due to large violent waves was investigated by using particle method.

• ETRI Journal
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• v.28 no.4
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• pp.506-508
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• 2006

A frequency selective surface (FSS), whose unit cell consists of a ternary tree loop loaded with a modified tripole, is proposed to block multiple frequency bands. Target frequency bands correspond to Korean personal communication services, cellular mobile communication, and 2.4 GHz industrial, scientific, and medical bands. Through the adjustment of inter-element and inter-unit cell gaps, and adjustment of the length of elements, we present an FSS design method that makes the precise tuning of multiple resonance frequencies possible. Additionally, to verify the validity of our approach, simulation results obtained from a commercial software tool and experimental data are also presented.

• Atmosphere
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• v.31 no.5
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• pp.525-537
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• 2021

Black ices on road surfaces in winter tend to cause severe and terrible accidents. It is very difficult to detect black ice events in advance due to their localities as well as sensitivities to surface and upper meteorological variables. This study develops a methodology to detect the road sections vulnerable to black ice with the use of road surface temperature data obtained from a mobile road weather observation vehicle. The 7 experiments were conducted on the route from Nam-Wonju IC to Nam-Andong IC (132.5 km) on the Jungang Expressway during the period from December 2020 to February 2021. Firstly, temporal road surface temperature data were converted to the spatial data with a 50 m resolution. Then, the spatial road surface temperature was normalized with zero mean and one standard deviation using a simple normalization, a linear de-trend and normalization, and a low-pass filter and normalization. The resulting road thermal map was calculated in terms of road surface temperature differences. A road ice index was suggested using the normalized road temperatures and their horizontal differences. Road sections vulnerable to black ice were derived from road ice indices and verified with respect to road geometry and sky view, etc. It was found that black ice could occur not only over bridges, but also roads with a low sky view factor. These results are expected to be applicable to the alarm service for black ice to drivers.

• Transactions on Electrical and Electronic Materials
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• v.8 no.6
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• pp.289-292
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• 2007

Polymethly methacrylate(PMMA) and polydimethlysiloxane(PDMS) surfaces were treated to improve adhesiveness by irradiation of a Nd:YAG pulse laser beam($\lambda=266nm$). A pulse laser beam was directed on a polymer surface in air, and the number of pulses was controlled by mobile velocity of a motorized stage. The laser treated surfaces were investigated using an optical microscope and a contact angle measuring instrument. It was thereby revealed that the contact angles were decreased in the laser treated surface. This in turn led to an increase of oxygen content and improved adhesiveness on the modified surface. With improved surface adhesion, a fluid channel could be formed on the laser treated surface region.

• Journal of the Korean Chemical Society
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• v.64 no.3
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• pp.153-158
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• 2020

With the recent popularity of mobile devices, the demand for lithium-ion batteries is increasing. In this study, the surface treatment process for the development of the Al (aluminum) lead tab for positive electrode, a key component of the pouch-type lithium-ion battery, was investigated. Anodizing and sealing processes were tested as surface treatment techniques. It was found that only a sealing process is needed to obtain sufficient adhesive strength. In the present study, an adhesive strength of 17 N/12 mm was achieved by degreasing and etching pretreatment, followed by a sealing process of 10 min duration. This adhesive strength was greater than that achievable using Cr (chromium) surface treatment. Using various surface analysis techniques, the shape and composition of the surface before and after being subjected to the surface treatment were compared and analyzed. The results of this study are expected to contribute to the development of an eco-friendly lead tab.

• Wind and Structures
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• v.12 no.4
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• pp.349-381
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• 2009

Since 1998, several institutions have deployed mobile instrumented towers to collect research-grade meteorological data from landfalling tropical cyclones. This study examines the wind flow characteristics from seven landfalling tropical cyclones using data collected from eight individual mobile tower deployments which occurred from 1998-2005. Gust factor, turbulence intensity, and integral scale statistics are inspected relative to changing surface roughness, mean wind speed and storm-relative position. Radar data, acquired from the National Weather Service (NWS) Weather Surveillance Radar - 1988 Doppler (WSR-88D) network, are examined to explore potential relationships with respect to radar reflectivity and precipitation structure (convective versus stratiform). The results indicate tropical cyclone wind flow characteristics are strongly influenced by the surrounding surface roughness (i.e., exposure) at each observation site, but some secondary storm dependencies are also documented.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.3 no.2
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• pp.206-214
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• 2003

In this paper, we propose a method to avoid obstacles that have unstable limit cycles in a chaos trajectory surface. We assume all obstacles in the chaos trajectory surface have a Van der Pol equation with an unstable limit cycle. When a chaos robot meets an obstacle in an Arnold equation or Chua's equation trajectory, the obstacle reflects the robot. We also show computer simulation results of Arnold equation and Chua's equation and random walk chaos trajectories with one or more Van der Pol obstacles and compare the coverage rates of each trajectory. We show that the Chua's equation is slightly more efficient in coverage rates when two robots are used, and the optimal number of robots in either the Arnold equation or the Chua's equation is also examined.

• Journal of the Korean institute of surface engineering
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• v.27 no.5
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• pp.303-311
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• 1994

In this study, the factors, such as coating temperature T(K), reaction time t(sec) and mobile carbon content $C^*$ (wt%) of steels affecting, the growth rate of carbide layer were investigated in the reactive deposition and diffusion coating using the fluidized bed. From the results, the coating thickness d(cm) can be expressed by an equation. d=$C^*$$(KT)^{1/2}$, where K=K$\circ$exp(~Q/RT), KTEX>$\circ$ = 1.4$\times$$10^{-2}cm^{-2}$/sec, and Q=46Kcal/ mol. It was in a good aggrement with the experimental results, reguardless of the diffusion coating method and the carbide layer. Therefore, if the mobile carbon content of carbon steels and alloyed steels is known, the thickness under coating conditions can be predicted from the previous equation.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2003.10a
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• pp.297-302
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• 2003

Recently, Flood hazard has been increased frequently in urban area by rainfall and Typhoon. To manage flood hazard effectively, it needs to construction of flood information management system. Especially, run-off by flood in urban area must be considered not only surface outflow by topographic gradient and elevation but also conduits outflow along conduit network. This paper suggests the flood hazard management system for analyzing flood outflow in urban area using conduits outflow simulation by ILLUDAS model and providing quickly flood hazard information using WebGIS and MobileGIS.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.91.3-91
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• 2001

A sensor fusion scheme for mobile robot environment recognition that incorporates range data and contour data is proposed. Ultrasonic sensor provides coarse spatial description but guarantees open space with no obstacle within sonic cone with relatively high belief. Laser structured light system provides detailed contour description of environment but prone to light noise and is easily affected by surface reflectivity. Overall fusion process is composed of two stages: Noise elimination and belief updates. Dempster Shafer´s evidential reasoning is applied at each stage. Open space estimation from sonar range measurements brings elimination of noisy lines from laser sensor. Comparing actual sonar data to the simulated sonar data enables ...