• Tribology and Lubricants
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• v.27 no.4
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• pp.218-223
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• 2011

To improve the performance of a bent-axis type axial piston pump driven by the tapered pistons, it is necessary to know the pressure ripple characteristics. The purpose of this paper is to understand the effect on the pressure ripple characteristics and the prediction by comparing experimental and theoretical results. The simulation model of the bent-axis type axial piston pump is developed in the AMESim environment using the geometrical dimension and the driving mechanism of the piston pump. The results can be obtained to predict the performance characteristics of the bent-axis type axial piston pump.

• Journal of Power Electronics
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• v.9 no.3
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• pp.430-437
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• 2009

This paper presents the dynamic characteristics of buck and buck-boost dc-dc converters with digital filters. At first, the PID, the minimum phase FIR filter and the IIR filter controls are discussed in the buck dc-dc converter. Comparisons of the dynamic characteristics between the buck and buck-boost converters are then discussed. As a result, it is clarified that the superior dynamic characteristics are realized in the IIR filter method. In the buck converter, the undershoot is less than 2% and the transient time is less than 0.4ms. On the other hand, in the buck-boost converter, the undershoot is about 3%. However, the transient time is approximately over 4ms because the output capacitance is too large to suppress the output voltage ripple in this type of converter.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08b
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• pp.1391-1394
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• 2007

In this work, the discharge characteristics and temporal distribution of surface charges on the Sidoped MgO have been investigated and elucidated with the results of photon-induced surface current. Even though the Si doped MgO shows lower static voltage margin, higher luminous efficacy, and shorter statistical delay time, its discharge characteristics become deteriorated as the timing of scanning is delayed from the ramp type reset pulse down. Overall features of Si-doped MgO in discharge characteristics are well correlated with surface current characteristics.

• Journal of IKEEE
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• v.20 no.4
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• pp.416-419
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• 2016

When the integration density and operating frequency increase in the electronic circuits, it is important to improve the signal transmission characteristics. In this paper, the signal transmission characteristics of the printed circuit boards are analyzed with the curvature of the pads. From the simulation results, signal transmission characteristics are improved when pad curvature increases. Pad curvature more effects on signal transmission characteristics when the thickness of the transmission line and the length of the transmission decrease.

• Wind and Structures
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• v.20 no.2
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• pp.293-314
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• 2015

In this paper, wireless monitoring of typhoon-induced variation of dynamic characteristics of a cable-stayed bridge is presented. Firstly, cable-stayed bridge with the wireless monitoring system is described. Wireless vibration sensor nodes are utilized to measure accelerations from bridge deck and stay cables. Also, modal analysis methods are selected to extract dynamic characteristics. Secondly, dynamic responses of the cable-stayed bridge under the attack of two typhoons are analyzed by estimating relationships between wind velocity and dynamic characteristics. Wind-induced variations of deck and cable vibration responses are examined based on the field measurements under the two consecutive typhoons, Bolaven and Tembin. Finally, time-varying analyses are performed to investigate non-stationary random properties of the dynamic responses under the typhoons.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.1
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• pp.58-64
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• 2016

In this paper, the design of rotor shape was performed for improvement of start-up characteristics and efficiency in single-phase LSPM. In order to improve the start-up characteristics, shape of rotor aluminium cage bar was changed. Through arrangement of permanent magnets and installation of flux barriers, it was performed torque ripple reduction and efficiency improvement. Cogging torque and back-EMF is calculated by the no-load analysis, start-up time is calculated by the start-up state analysis, efficiency and torque ripple is calculated by steady state analysis. The characteristics of the motor were calculated through FEM.

• KIEE International Transactions on Electrophysics and Applications
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• v.2C no.6
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• pp.321-326
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• 2002

This paper describes the mechanical and electrical characteristics of insulating paper impregnated with diluted varnish(W-128), according to Korean Standards. The varnish was diluted with a solvent of 6 different wt%. Kraft paper and Nomex paper were impregnated with the diluted varnish in a vacuum condition, and then completely dried. As the mechanical characteristics, the thickness of the completely dried varnish, the drying time and the tensile strength of the specimens were measured, and as the electrical characteristics, the permittivity, the tan $\delta$ and the specific resistance were evaluated as well.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.11
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• pp.34-41
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• 2001

This study is to investigate the energy absorption characteristics of CFRP(Carbon-Fiber Reinforced Plastics) tubes on static and dynamic tests. Axial static compression tests have been carried out using the static testing machine(Shin-gang buckling testing machine) and dynamic compression tests have been utilized using an vertical crushing testing machine. When such tubes are subjected to crushing loads, the response is complex and depends on the interaction between the different mechanisms that could control the crushing process. The collapse characteristics and energy absorption have been examined for various tubes. Energy absorption of the tubes are increased as changes in the lay-up which may increase the modulus of tubes. The results have been varied significantly as a function of ply orientation and interlaminar number.

• Transactions on Electrical and Electronic Materials
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• v.1 no.4
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• pp.16-19
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• 2000

Power transistors to be used in Power Integrated Circuits(PIC) are required to have low on resistance, fast switching speed, and high breakdown voltage. The lateral IGBTs(LIGBTs)are promising power devices for high voltage PIC applications, because of its superior device characteristics. In this paper, dual cathode LIGBT(DCIGBT) for high voltage is presented. We have verified the effectiveness of high blocking voltage in the new device by using two dimensional devices simulator. We have analyzed the forward blocking characteristics , the latch up performance and turn off characteristics of the proposed structure. Specially, we have focused forward blocking of LIGBT. The forward blocking voltage of conventional LIGBT and the proposed LIGBT are 120V and 165V, respectively. . The forward blocking characteristics of the proposed LIGBT is better than that of the conventional LIGBT. This forward blocking comparison exhibits a 1.5 times improvement in the proposed LIGBT.

• Journal of Power System Engineering
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• v.18 no.4
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• pp.72-77
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• 2014

The aim of this study to investigate polarization characteristics of WC-based alloy coatings fabricated by high velocity oxygen fuel(HVOF) process. The coatings were fabricated by HVOF process with WC-CrC-Ni, WC-Co-Cr, WC-Co composite powders. Corrosion tests were carried out using potentiostat/galvanostat at solution with pH 2 and pH 6. Corrosion potential(Ecorr) and corrosion current density(Icorr) could be analyzed from polarization curve. WC-Co-Cr coating showed more incorrodible characteristics than other coatings at solution pH 2. WC-CrC-Ni coating was more favorable anti-corrosion characteristics than other coatings at solution with pH 6.