• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.9
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• pp.822-829
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• 2002

This paper deals with the distribution characteristics of the current density and axial magnetic flux density for each slits made on the contact electrode in the vacuum interrupter with axial magnetic field type using 3-dimension finite element analysis. It has been known that the presence of an axial magnetic field parallel to the current flow in the arc plasma can increase the high current breaking capacity of vacuum interrupter by carrying out the arc plasma from constricted mode to diffusion mode. The axial magnetic field is created of itself by current flow in the segments of coil electrode behind the contact electrode. The analyzed results show that if the slits are made in the contact electrode, they can increase the current density and axial magnetic flux density in the contact electrode surface and at the gap distance, which is due to decrease the effect of eddy currents flowing in the contact electrode. The phase shift due to eddy currents, defined 3s time difference between the maximum value of current and axial magnetic field, is decreased still more by increasing the number of slits made in the contact electrode at the center point of gap distance. These results demonstrate that 3-dimension finite element analysis has a great deal of merits in the development and evaluation of new electrode at the design of vacuum interrupter.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.543-544
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• 2006

This paper describes a simple real-time monitoring system for use in measurement subsystem of contact wire and geometry of overhead contact wire in electric railway. The system has been consists of a high speed CMOS camera with resolution $1024\;{\times}\;1280$ pixels, line type laser source with a power equal to 300 mW, and PC-based image acquisition system with PCI Express slot. National instrument LabVIEW (8.0) and vision acquisition software have been used in application programming interface for image acquisition, display, and storage with a frequency of sampling of 500 acquisitions per second.

• Journal of the Korean Ceramic Society
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• v.33 no.11
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• pp.1231-1236
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• 1996

The electrode resistance of semiconducting PTC BaTiO3 ceramic material was studied in some detail. Comme-rical In-Ag paste In-Ga alloy and electroless plated Ni as well as evaporated Al were chosen as electrode. The contact resistance of electroded samples were measured by both dc resistivity and ac impedance analysis. The aging effect on contact resistance under cyclic loading from -1$0^{\circ}C$ to 85$^{\circ}C$ was also monitored for the prolonged period of time. In case of Al electroded samples the heat treatment and protective coating had effects on the stability against contact resistance degradation. It was also found that the samples with commercial In-Ag paste and electroless plated Ni electrode had good properties of contact resistance against aging.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.16 no.6 s.111
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• pp.634-642
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• 2006

For the analysis of dynamic contact between a catenary and a pantograph of high-speed electrical train, the numerical solution of the equations of motion of the vehicle pantograph and the catenary system subjected to the contact condition is obtained. The whole equations of motion of the catenary and the pantograph are simultaneously time integrated with the strict application of the contact condition. For the stability of the numerical solution, with the cubic spline interpolation of the catenary displacement, the velocity and acceleration constraints as well as the displacement constraint are imposed on the contact point. Especially it is shown that the Coriolis and centripetal accelerations are critical for the accuracy and stability of the computation.

• Structural Engineering and Mechanics
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• v.82 no.5
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• pp.643-650
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• 2022

In this paper a novel mathematical model and its analytical solution of global buckling behaviour of slender elastic concrete-filled double-skin tubular (CFDST) columns with finite compliance between the steel tubes and a sandwiched concrete core is derived for the first time. The model is capable of investigating the influence of various basic parameters on critical buckling loads of CFDST columns. It is shown that the elastic buckling load of circular and slender CFDST columns is independent on longitudinal contact stiffness, but, on the other hand, it can be considerably dependent on circumferential contact stiffness. The increasing of the circumferential contact stiffness increases the critical buckling load. Furthermore, it is shown that analytical results can agree well with the experimental and numerical results if the calibrated values of circumferential contact stiffness are used in the calculations. Moreover, it is shown that the contact between the steel tubes and a sandwiched concrete core of tested large-scale CFDST columns used in the comparison is relatively weak. Finally, the proposed analytical results can be used as a benchmark solution.

• Polymer(Korea)
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• v.38 no.2
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• pp.220-224
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• 2014

Protein adsorption kinetics was studied with the amount of proteins adsorbed to contact lens hydrogels over time scales. Hydroxyethylmethacrylate (HEMA) and silicone hydrogels were dipped in protein solutions (albumin or IgG) and adsorption amounts were measured over time scales. The amount of protein adsorbed to both hydrogel types increased rapidly in 10 min, and remained consistently in 90 min. Decreasing interfacial energetics was taken slowly up to an hour in spite of rapid diffusion of protein molecules. This is due to the fact that water deprivation from three dimensional interphase initially formed by protein diffusion took over an hour. Interpretation of adsorption kinetics on contact lens hydrogels was discussed with understanding of relationship between surface energy and protein adsorption capacity.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2019.11a
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• pp.26-27
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• 2019

This study is to calculate the Real-Time contact point of ellipses between the vessels ships by Ship's Bumper Theory. The Real-Time contact point of ship's bumper ellipses can be used the important tool to feel the perceived risk evaluation of ship's collision risk by VTS operator. In this paper, The warning information to feel the risk of collision between the vessels in advance is able to help them for VTS operation, We will study the technique to certify the perceived risk of collision from several different angles by programming.

• Journal of Environmental Health Sciences
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• v.33 no.6
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• pp.493-496
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• 2007

The influences of contact time and ratio of food to microorganism (F/M) on uptake of wastewater organic matter in a short contact process were investigated using three activated sludge batch reactors fed with synthetic wastewater, sewage and livestock wastewater. About 64% of influent soluble chemical oxygen demand (SCOD) in the synthetic wastewater and 61% of SCOD in the sewage and 43% of SCOD in the diluted livestock wastewater were adsorbed into the activated sludge within 30 min. The specific mass of organic matter uptaken in the synthetic wastewater was 55 mg SCOD/g mixed liquor suspended solids (MLSS). In the same manner, 20 and 14 mg SCOD/g MLSS were calculated as the values in the sewage and livestock wastewater, respectively.

• IEMEK Journal of Embedded Systems and Applications
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• v.14 no.3
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• pp.123-131
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• 2019

In recent years, a non-contact respiration and heart rates monitoring via IR-UWB radar has been paid much attention to in various applications - patient monitoring, occupancy detection, survivor exploring in disaster area, etc. In this paper, we address a novel approach of real time heart rate estimation using IR-UWB radar. We apply sine fitting and peak detection method for estimating respiration rate and heart rate, respectively. We also deploy two techniques to mitigate the error caused by wrong estimation of respiration rate: a moving average filter and finding the frequency of the highest occurrence. Experimental results show that the algorithm can estimate heart rate in real time when respiration rate is presumed to be estimated accurately.

• Journal of Environmental Health Sciences
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• v.29 no.1
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• pp.74-83
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• 2003

Microcystin, stable compounds with circular heptapeptides, is presented inside cyanobacterial cell. So far, over 30 types have been known to exist and microcystin-LR, RR among them are the most potent toxin compound. By this reason, a strong oxidant, ozone was used in this study to remove the microcystins produced by cyanobacteria. Removal efficiency of microcystin at M water treatment plant was also evaluated. Microcystin concentration was determined by protein phosphatase inhibition assay. The results showed that dissolved microcystin in raw water detected in the range of 0.011-0.028 ㎍ Microcystin-RR equivalent/l. Above 98% of microcystin was removed through overall treatment system. Therefore, the water treatability of M treatment plant seemed to be excellent. Removal efficiency of microcystin according to unit process varied as characteristics of raw water such as DOC, UV/sub 254/ and turbidity. Removal efficiency of microcystin by ozonation was investigated in laboratory according to contact time and ozone dose. Dissolved microcystin was increased by twice fold according to ozone contact time, but increased by fifth fold according to ozone dose. So, changing of ozone dose more affected microcystin release than changing of ozone contact time. Behavior of microcystin by ozonation was similar to that of DOC, and residual ozone concentration gave influence to removal ratio of microcystin. In conclusion, single ozone treatment wasn't effective on microcystin removal in case of water containing a lot of cells. Therefore, it's more effective to use ozonation process after the removal of cyanobacterial cells in advance.