• Journal of Power Electronics
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• v.16 no.1
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• pp.102-110
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• 2016

Contactless power transfer technology is gaining increasing attention in city transportation applications because of its high mobility and flexibility in charging and its commensurate power level with conductive power transfer method. In this study, an inductively coupled contactless charging system for a 48 V light electric vehicle is proposed. Although this study does not focus on system efficiency, the generic problems in an inductively coupled contactless power transfer system without ferromagnetic structure are discussed. An active load matching method is also proposed to control the power transfer on the receiving side through a load matching converter. Small signal modeling and linear control technology are applied to the load matching converter for port voltage regulation, which effectively controls the power flow into the load. A prototype is built, and experiments are conducted to reveal the intrinsic characteristics of a series-series resonant inductive power charger in terms of frequency, air gap length, power flow control, coil misalignment, and efficiency issues.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.7
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• pp.992-997
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• 2012

In this paper, we were analyzed the vibration characteristics of the three-phase cast resin transformer using less than 50% of load in the field. Most of the cast resin transformer is less than 50% in the domestic field is used for load conditions. Consisting of a solid insulator cast resin transformer is generating lots of noise and vibration. In addition, because it is affected by Joule 's heat is used in light load conditions. As a results, the transformer vibrations at frequencies below about from 200Hz to 500Hz were detected. Vibration velocity depends on the load variations were found. Load up to approximately 20-30% in most cases the vibration velocity was found at 4,000 ${\mu}m/s$ or less, 8,000 ${\mu}m/s$ or more. Vibration frequency at light load conditions were generated at the 120Hz, 240Hz, 360Hz and 480Hz. At the load condition of from 10% to 20%, vibration velocity is higher than another. Most of the vibration velocity were identified at the 1,000 ${\mu}m/s$ or less. Using the vibration frequency and velocity measurements data, the load on the cast resin transformer analyzed the correlation of the burden. Therefore, this data could be found in the vibration characteristics of the light-load conditions. If the field measurements using the data perform diagnostics on the transformer, it's expected to be very effective.

• Journal of the Korean Society of Safety
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• v.22 no.6
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• pp.13-19
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• 2007

Diesel car's smoke measurement equipment and method were investigated based on the exhaust gas regulations. Reflection photo method and light extinction method for measuring smoke were compared under conditions of both no load mode and Lug-down 3 mode. Free acceleration mode at no load condition was used for regular inspection of diesel car, and Lug-down 3 mode was used for fine inspection of the diesel car. A correlation between no load mode and Lug-down 3 mode was investigated in this research. The smoke measured with reflection photo method was 1.5${\sim}$2 times higher than that of light extinction method The correlation coefficient between reflection photo method and light extinction method for measuring smoke was 0.83, which shows comparatively high correlation between the two methods for measuring smoke in diesel engines.

• Journal of Korean Society of Steel Construction
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• v.16 no.4 s.71
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• pp.453-461
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• 2004

Since there are no specifications in Korea regarding the design of steel column baseplates that are subjected to concentric axial load, this paper proposes a more accessible stress design method for baseplates based on AISC specifications and guidelines.Some designs included in this paper were: (1) a full area ofconcrete bearing pressure under normal axial load and subsequent failure in external cantilevers at 0.95 d or 0.8 bf, and (2) a partial area of the pressure under a light axial load and subsequent failure as an internal cantilever model.

• Journal of Communications and Networks
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• v.17 no.4
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• pp.370-383
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• 2015

Effective link quality estimation is a vital issue for reliable routing in wireless networks. This paper studies the performance of expected transmission count (ETX) under different traffic loads. Although ETX shows good performance under light load, its performance gets significantly worse when the traffic load is high. A broadcast packet storm due to new route discoveries severely affects the link ETX values under high traffic load, which makes it difficult to find a good path. This paper presents the design and implementation of a variation of ETX called high load - ETX (HETX), which reduces the impact of route request broadcast packets to link metric values under high load. We also propose a reliable routing protocol using link quality metrics, which is called link quality distance vector (LQDV). We conducted the evaluation of the performance of three metrics - HETX, ETX and minimum hop-count. The simulation results show that HETX improves the average route throughput by up to 25% over ETX under high traffic load. Minimum hop-count has poor performance compared with both HETX and ETX at all of the different traffic loads. Under light load, HETX and ETX show the same performance.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.11a
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• pp.356-360
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• 2006

Recently, for the purpose of improving the isolation performance of impact noise, many resilient materials have been installed in a residential building. As one of the reduction method for improving the performance of light-weight impact noise, this study is focused on the load condition of floating layer over resilient material. We studied the correlation between the mass or load of the floating layer and the reduction of light-weight impact noise by experiments in reverberation chamber for testing the impact noise. The results show that the reduction of impact noise is improved by increasing the mass per unit area of floating layer until about $140kg/m^2$. But the reduction is not obvious by adding extra mass on the floating layer.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.09a
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• pp.219-224
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• 2009

In this study, the characteristics of pullout behavior of Pressurized light-weight steel Anchor was investigated through centrifuge model tests considering pull-out angle $0^{\circ}$ with changing undrained shearstrength(0~1, 2~4, 5~7kPa) of clay. According to the results of tests, the yield pullout load of clay ground was gradually increased up to 30% as undrained shear strength was increased. Therefore, it was known that the yield pullout load was affected by increasing the undrained shear strength, in addition, the pattern of behavior was not changed.

• Proceedings of the KSR Conference
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• 2006.11b
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• pp.238-244
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• 2006

The Light Collision Safety Device is used to protect the important part of trains and passengers at the low velocity accidents. The Light Collision Safety Device comprises mainly tension bolts, shear bolts and an energy absorber. The work mechanism of this device is that first, the tension bolts break at designed collapse load and second, the energy absorber absorb rest collision energy. In this paper, the tension bolt characteristics were validated by the simple tension test using the FEM(Finite Element Method) and the characteristic of the two types of energy absorber were compared by using the load-displacement curves and absorbed energy. Last, in order to determine integrated load-displacement curve of tension bolts and the energy absorber, the unified analysis was conducted by using the FEM.

• KIEE International Transactions on Electrophysics and Applications
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• v.4C no.3
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• pp.101-105
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• 2004

The efficient power MOSFET inverter applied for a simple and low cost power supply is proposed for driving the dielectric barrier discharge (DBD) lamp load. For decades, the DBD phenomenon has been used for ozone gas production in industry. In this research, the ultraviolet and visible light sources utilizing the DBD lamp is considered as the load for solid-state high frequency power supply. It is found that the simple voltage-source single-ended quasi-resonant ZVS inverter with only one active power switch could effectively drive this load with the output power up to 700 W. The pulse density modulation based control scheme for the single-ended quasi-resonant ZVS inverter using a low voltage and high current power MOSFET switching device is proposed to provide a linear power regulation characteristic in the wide range 0-100％ of the full power as compared with the conventional control based Royer type parallel resonant inverter type power supplies.

• Proceedings of the KIPE Conference
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• 2013.07a
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• pp.184-185
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• 2013

In this paper, design of a variable inductor using MR Fluid Gap is proposed for wide load range efficiency improvement of a bidirectional DC-DC converter. As compared to conventional constant value inductor designed to have negative current for ZVS at heavy load but suffers high losses at light load due to its small inductance, the proposed variable inductor not only have small inductance at high current for ZVS but also it has large inductance at low current to decrease light load losses.