• Transactions of the Korean Society of Automotive Engineers
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• v.19 no.2
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• pp.72-77
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• 2011

In this paper, we propose effective diagnosis algorithm for hub bearing fault in driving vehicle using acceleration signal and wheel speed signal measured in hub bearing unit or knuckle. This algorithm consists of differential, envelope and power spectrum method. We developed diagnosis system for realizing proposed algorithm. This system consists of input device including acceleration sensor and wheel speed sensor, calculation device using Digital Signal Processor (DSP) and display device using Personal Digital Assistant (PDA). Using this diagnosis system, a driver can see hub bearing fault(flaking) from the vibration in driving vehicle. With early repairing, he can keep good ride feeling and prevent accident of vehicle resulting from hub bearing fault.

• The Journal of the Acoustical Society of Korea
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• v.15 no.1
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• pp.10-16
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• 1996

Ultrasonic motor is a motor driven by the stator via frictional contact forces generated from ultrasonic vibration of piezoelectric elements. In order to control the ultrasonic motor, it is essential to measure accurately the motor characteristics with respect to driving parameters such as frequency, voltage, phase difference and duty ratio of the driving signals. In this paper, a PC-interfaced evaluation device is developed, and the characteristic curves of the fabricated ultrasonic motor are measured with those parameters. All driving parameters are processed digitally. The developed evaluation device can facilitate charateristics measurements effectively, and provide a base for digital control of the ultrasonic motor.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.10
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• pp.1540-1546
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• 2017

In piezoelectric device applications, it is important to improve a system efficiency because of the low generated power. In this paper, an optimal driving method is proposed to improve a system efficiency for a piezoelectric energy harvesting system. The proposed method considers disappear energy in input capacitors and the converter efficiency according to the input voltage magnitude to minimize energy losses. Experimental results based on various energy generation cases verify that the proposed method significantly improves the system efficiency; the efficiency is approximately 9.97% higher than that of the conventional method.

• Journal of the Korean Society of Industry Convergence
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• v.18 no.1
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• pp.37-44
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• 2015

In the research, we developed a device for cooling the drive section of the gripper of a robot for handling the high temperature material. In this study, By using a Peltier element, the high-temperature material is not affected and driving cylinder is cooled to prevent damage due to high temperatures. Hot part of the Peltier element is towards the robot gripper. Cool part of the Peltier element is towards the driving cylinder. The heat sink portion is made to keep the cooling effect. As the performance result, cooling-test is taken, and their result is satisfy.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.36 no.4
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• pp.397-402
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• 2023

We have developed inverted green phosphorescent organic light emitting diodes (OLEDs) using 1,1-bis[(di-4-tolylamino)phenyl]cyclohexane (TAPC) and bis(carbazole-9-yl)biphenyl (CBP) hole transport layers. The driving voltage, current efficiency, power efficiency, and emission characteristics of devices were investigated. While the driving voltage for the same current density was about 1~2 V lower in the devices with the TAPC layer, the maximum luminance was higher in the device with the CBP layer. The maximum current efficiency and power efficiency were 3.2 and 2.7 times higher in the device with the CBP layer, respectively. The higher efficiency in the CBP device resulted from the enhanced hole-electron balance although weak parasitic recombination takes place in the CBP hole transport layer.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.6
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• pp.576-581
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• 2005

We fabricated red organic light emitting diodes(OLEDs) utilizing tis(8-hydroxyquinoline) aluminum $(Alq_3)$ doped with $5\%$ of (4-(dicyanomethylene)-2-i-propyl-6-(1,1,7,7-tetramethyljulolidyl-9-enyl)-4H-pyran) (DCJTI) and investigated the driving and modulation characteristics for applying to the electro-optical conversion device. To improve the driving characteristics of red OLEDs, 3 V of offset voltage, which is equal to the turn on voltage, Is applied to the device. Offset voltage enhanced the optical EL output and reduced the rise time of EL waveforms of red OLEDs, and hence the cutoff frequency is increased with increasing applied voltage. The optical pulse of 100 MHz has been obtained from red OLEDs. Therefore, we confirmed that the red OLEDs can be applied to the fields of optical communication as an electro-optical conversion device.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2000.11a
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• pp.60-63
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• 2000

In this paper, 7-segment was implemented using AC powder EL. ZnS:Cu and BaTiO3 was used as a phosphor and dielectric respectively. The preparation of phosphor and dielectric layer was performed with screen printing. The implemented system of 7-segment was divided as following; EL display, driving circuit, software for driving. The properties of fabricated devices was measured with EL spectrum and brightness.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.17 no.3
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• pp.59-64
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• 2018

In general, tracked combat vehicles require excellent output performance of a power unit system to drive on special terrains and in extreme environmental conditions. However, high temperature and pressure are readily applied to the coolant hose in the power unit of the vehicles during high-speed driving under extreme road and weather conditions. These driving conditions can cause the separation phenomenon of the coolant hose in the power unit and consequentially engine overheating during driving. Therefore, a newly designed decompression device for the coolant hose has been proposed and manufactured to solve these problems in the present study. To validate of the newly proposed decompression device, the input and output pressures were measured under the before- and after-improvement conditions using experimental methods for different engine RPMs. In addition, the pre-heater temperature was measured under both conditions. From the experimental results, we expect that the current investigation can help to improve the driving performance of tracked combat vehicles.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.53 no.4
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• pp.237-246
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• 2004

The advantages of the Magnetic Fluid Linear Pump(MFLP) is that this device could Pump the non-conductive. non-magnetic liquid such as Insulin or blood because of the segregation structure of the magnetic fluid and pumping liquid. In this device. the sequential currents are needed to Produce pumping forces so that Pumping Forces and Pumping speed mainly depend on the current Patterns. The excessive forces at Pumping moment could cause the medical shock, and weak forces at intermediate moment could cause the back flow or the pumping liquid. So the ripples of the pumping forces need to be reduced for the medical application. In this research, the driving characteristics in the MFLP by operating current is analysed. The change of magnetic fluid surface according to the driving currents could be obtained be magneto-hydrodynamic analysis so that Pumping fortes could be computed by integration of the surface moving to the pumping direction at each moment. The actual MFLP with 13mm diameter was made and tested for experiments. The effects of driving current and frequency on the pumping forces and pumping speed were analyzed and compared with experimental measurements.

• Journal of Auto-vehicle Safety Association
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• v.12 no.1
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• pp.33-38
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• 2020

Since a diesel vehicle scandal related to the 'A' automobile company was issued in the United States in 2015, many countries have been interested in emission defeat devices. Being embedded in some diesel passenger cars sold in Korea, a defeat device for exhaust gas may have influence on both fuel economy and NOx emissions. In order to examine such effects, we carried out laboratory indoor tests as well as real road driving tests using four models of 'A' automobile company which may employ defeat devices. Those tests were performed observing the test modes of FTP-75, HWFET, and NEDC. Although fuel economy and NOx emissions according to indoor tests comply with the suggested tolerance, the findings in the real road driving tests do not satisfy the tolerance. Along with the results provided in this study, further evaluation may be necessary to investigate the noticeable difference between the indoor and real road tests.