• Progress in Superconductivity and Cryogenics
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• v.15 no.4
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• pp.21-25
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• 2013

In power grid, in order to level out the generation with demand, up-gradation of the system is occasionally required. This will lead to more fault current levels. However, upgrading all the protection instruments of the system is both costly and extravagant. This issue could be dominated by using Smart Fault Current Controller (SFCC). While the impact of Fault current Limiters (FCL) in various locations has been studied in different situations for years, the performance of SFCC has not been investigated extensively. In this research, SFCC which has adopted the characteristics of a full bridge thyristor rectifier with a superconducting coil is applied to three main locations such as load feeder, Bus-tie position and main feeder location and its behavior is investigated through simulation in presence and absence of small Distributed Generation unit (DG). The results show a huge difference in limiting the fault current when using SFCC.

• Proceedings of the KSR Conference
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• 2003.05a
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• pp.46-52
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• 2003

In this study, the full scale testing method of the geogrid-reiuorced soil Segmental Retaining Walll(SRW) under the simulated train loading were proposed in order to evaluate the applicability of reinforced soil SRW in railway embankment. The train loading was simulated by the design static wheel load and the impact coefficient due to the train passing velocity. This test was focused on the static performance of reinforced soil SRW in terms of the following measuring systems ; the horizontal earth pressure displacement acting on the facing block and the tensile strain along the geogrid. The data gathered from this full scale testing was compared with numerical analysis results by FLAC.

• Journal of Information Display
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• v.12 no.2
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• pp.85-87
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• 2011

The contrast ratio is one of the most important performance parameters for display devices. The general method of measuring the contrast ratio is to determine the ratio of the full-screen white pattern to the full-screen black pattern, according to the Video Electronics Standards Association standard. Real TV images seldom have these images, however, and the conventional method does not reflect the true performance of the display in actual use. In this paper, a new contrast ratio measurement method that uses image patterns is proposed, to demonstrate that active matrix organic light-emitting diode TVs have a higher contrast than LED (LCD) TVs.

• Journal of the Korean Institute of Navigation
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• v.14 no.2
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• pp.15-31
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• 1990

Recently, there is a tendency to design the large full ships with lower-powered engine as the means for energy saving in ship's navigation at seas. Such a lower-powered ship is anticipated to show the different propulsive performance in rough seas, because the fluctuation of main engine load of lower powered ship is relatively large as compared with higher-powered ship is relatively large as compared with higher-powered ship. The fluctuation of propeller load is nonlinear at racing condition in waves. It is due to the variation of inflow velocity into propeller, the propeller immersion and the characteristics of engine governor. In this paper, the theoretical calculation of the nominal speed loss and the numerical simulation for the nonlinear load fluctuation of a model ship in rough seas are carried out. From the results of calculation, the following are discussed. (1) The ratio of nominal speed loss to the speed in still water. (2) The manoeuvring ability of ship and the operational ability of main engine in a seaway. (3) A method of the evaluation for the fluctuation of propeller torque and revolution on the engine characteristics plane. (4) The effect of engine governor characteristics on the propeller load fluctuation.

• Computers and Concrete
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• v.24 no.2
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• pp.159-172
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• 2019

This paper presents an investigation into the flexural behavior of reinforced concrete (RC) beams retrofitted by ultra-high performance fiber-reinforced concrete (UHPFRC) layers. The experimental study has been conducted in two parts. In the first part, four methods of retrofitting with UHPFRC layers in both the up and down sides of the beams have been proposed and their efficiency in the bonding of the normal concrete and ultra-high performance fiber-reinforced concrete has been discussed. The results showed that using the grooving method and the pre-casted UHPFRC layers in comparison with the sandblasting method and the cast-in-place UHPFRC layers leads to increase the load carrying capacity and the energy absorption capacity and causes high bond strength between two concretes. In the second part of the experimental study, the tests have been conducted on the beams with single UHPFRC layer in the down side and in the up side, using the effective retrofitting method chosen from the first part. The results are compared with those of non-retrofitted beam and the results of the first part of experimental study. The results showed that the retrofitted beam with two UHPFRC layers in the up and down sides has the highest energy absorption and load carrying capacity. A finite element analysis was applied to prediction the flexural behavior of the composite beams. A good agreement was achieved between the finite element and experimental results. Finally, a parametric study was carried out on full-scale retrofitted beams. The results indicated that in all retrofitted beams with UHPFRC in single and two sides, increasing of the UHPFRC layer thickness causes the load carrying capacity to be increased. Also, increases of the normal concrete compressive strength improved the cracking load of the beams.

• Journal of the Korea institute for structural maintenance and inspection
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• v.27 no.2
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• pp.1-7
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• 2023

Durability was evaluated by performing a full-scale vertical load fatigue test and a wheel load performance test on the HRS, which reduces the replacement time of the existing expansion joint and improves serviceability to allow partial replacement by lane. As a result of the vertical load fatigue test, the maximum stress of the rail-type expansion joint is 170 MPa, which is about 47.8% of the yield strength of the HRS expansion joint rail 355 MPa. The vertical load fatigue test of the HRS expansion joint with improved serviceability set the size and load of the load plate according to the road bridge design standards, did not show any fracture behavior in the vertical load fatigue test and the wheel load performance test 2 million times, and its durability and safety were verified.

• 전자공학회논문지 IE
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• v.43 no.2
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• pp.49-53
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• 2006

A fast motion-estimation algorithm based on regulated partial block distortions is proposed. The proposed algorithm can obtain very accurate motion vectors with a small computational load. Simulation results show that the proposed scheme provides very close performance to the full search while it is about 6 to 28 times faster than the full search.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.16 no.3
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• pp.56-63
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• 2007

Modern diesel vehicle has to comply with the EURO IV, V regulation with low level of particulate matter and smoke emission Moreover, emission standards of each countries are becoming stringent in advanced countries such as USA and Europe. Because Bio-diesel is similar to diesel fuel, it is essential to judge the environmental and health effects deriving from the use of Bio-diesel in diesel engine. The deterioration characteristics of emission in accordance with aging vehicles must be regulated for Bio-diesel. Therefore, under 1200 driving hours, 220,000km driving distance condition and full load, the deterioration characteristics of emission were estimated. We could reduce sulfur contents of fuel, particulate matter and smoke emission by using Bio-diesel and conform the influence of engine performance, emission, and fuel consumption by Bio-diesel deterioration

• Transactions of the Korean Society of Automotive Engineers
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• v.8 no.6
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• pp.40-50
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• 2000

In this study, as a means of increasing engine power, turbocharging was applied to the gasoline engine of a light passenger car which was originally naturally aspirated. Also the catalytic convertor was applied to improve the exhaust emission characteristics. The comparison of the performance characteristics between the burbocharged engine with catalytic convertor and the naturally aspirated engine was made over the wide range of operating conditions. The results showed considerable increase of the output performances at full load condition by trubocharging while slight losses were observed at part load conditions.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.11a
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• pp.295-298
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• 2005

In General, post-installed dowel bars are used as a shear connector to ensure the composite actions between new slabs and existing slabs in an apartment remodelling constructions expecially for enlarging the interior space outward the existing buildings. But, it has not been checked that the connection performance between existing and new slab is satisfactory not only for the structural safety condition but also the for serviceability and dwelling requirements. In this research, an experimental works were presented to evaluate the load transfer capacity for the planar joints between existing and new slab. The existing slabs were obtained from the existing apartment housing which will be demolished. Test results showed that the planar joints with post-installed dowel bars behaved in full composite modes until ultimate capacity of test specimens, so sufficient ultimate and serviceability performance are confirmed.