• The Transactions of the Korean Institute of Electrical Engineers B
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• v.51 no.6
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• pp.285-291
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• 2002

In general, utility voltage is maintained at a relatively low level of Phase unbalance since a low level of unbalance can cause a significant power supply ripple and heating effects on the power system equipment. Voltage unbalance more commonly emerges in individual customer loads due to phase load unbalanced, especially where single phase power loads are used. Under unbalanced input voltages large lower order harmonics appears at the input and output ports of Power conversion devices. As the application of adjustable -speed drives (ASDs) and their integration with complex industrial processes increase, so does the need to understand how ASDs perform during voltage This paper describes a real load test to investigate the performance of 3-HP adjustable speed drives by an unbalanced voltage at the low-voltage system.

• Journal of Advanced Marine Engineering and Technology
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• v.26 no.6
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• pp.631-637
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• 2002

Two stroke low speed diesel engines are used as a power supplier not only for marine vessel but also diesel power plant with a benefit of its higher mobility and durability than the other thermal engines. However, there are some disadvantages such as the bigger vibrating excitation forces generated by high combustion pressure in cylinders which various kinds of vibrations are caused. In this paper, it is theoretically studied to control engine body vibration using dynamic vibration absorber. As an actual case, dynamic absorbers are designed for controlling X-mode vibration of 9K80MC-S engine on the diesel power plant and its performance is identified by the vibration test both in shop and site

• Journal of Power Electronics
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• v.8 no.1
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• pp.51-59
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• 2008

This paper addresses several issues concerning the analysis, design, modeling, simulation and development of single-phase, single-switch, power factor corrected AC-DC high frequency switching converter topologies with transformer isolation. A detailed analysis and design is presented for single-switch topologies, namely forward buck, flyback, Cuk, Sepic and Zeta buck-boost converters, with high frequency isolation for discontinuous conduction modes (DCM) of operation. With an awareness of modem design trends towards improved performance, these switching converters are designed for low power rating and low output voltage, typically 20.25W with 13.5V in DCM operation. Laboratory prototypes of the proposed single-switch converters in DCM operation are developed and test results are presented to validate the proposed design and developed model of the system.

• Journal of Power Electronics
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• v.7 no.4
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• pp.318-327
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• 2007

The design and performance analysis of a power factor corrected (PFC), single-phase, single switch flyback buck-boost ac-dc converter is carried out for low power battery charging applications. The proposed configuration of the flyback buck-boost ac-dc converter consists of only one switch and operates in discontinuous current mode (DCM), resulting in simplicity in design and manufacturing and reduction in input current total harmonic distortion (THD). The design procedure of the flyback buck-boost ac-dc converter is presented for the battery charging application. To verify and investigate the design and performance, a simulation study of the flyback buck-boost converter in DCM is performed using the PSIM6.0 platform. A laboratory prototype of the proposed single switch flyback buck-boost ac-dc converter is developed and test results are presented to validate the design and developed model of the system.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.11C
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• pp.1098-1105
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• 2009

In this paper, we propose an asynchronous UWB (Ultra Wide Band) Positioning scheme that can provide precise positioning performance with low complexity and low power consumption. We also present the residual test to improve the positioning performance in multipath channels having heavy NLoS (Non-Line of Sight) components. As compared to conventional ToA (Time of Arrival) positioning scheme that requires round-trip transmissions as many as the number of beacons, the proposed UWB positioning scheme effectively decrease power consumption and processing delay since a single round-trip transmission is only required. Also, as compared to conventional TDoA (Time Difference of Arrival) positioning scheme requiring precise synchronization among the beacons, asynchronous nature of the proposed scheme achieves very low system complexity. Through simulations in LoS (Line of Sight) channel models, we observe that the proposed scheme requires low system complexity, low power consumption, while providing positioning performance of almost the same accuracy as the conventional ToA and TDoA positioning schemes. In addition, the proposed scheme by employing the residual test achieves accurate positioning performance even in multipath channels having heavy NLoS components.

• Journal of Drive and Control
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• v.19 no.3
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• pp.32-38
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• 2022

The in-wheel drive gearbox for military special vehicles converts the high-speed & low-torque output generated by the electric servomotor, into low-speed & high-torque mechanical power. As the vehicle is remotely maneuvered in mountainous terrain, wet fields, rough terrain, etc., the gearbox must generate a maximum input speed exceeding 5,000 rpm, a maximum torque of 245 Nm, and MTBF of 9,600 km. The purpose of this study was to analyze the failure mode of the gearbox, to ensure the durability of the in-wheel drive gearbox. Also, the field load test data of the vehicle was analyzed, the acceleration durability test standards were established, the acceleration durability test was conducted, and the durability test results were analyzed as well.

• 전자공학회논문지 IE
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• v.45 no.3
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• pp.5-12
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• 2008

We propose efficient scan testing method capable of reducing the test data and power dissipation for digital logic circuits. The proposed testing method is based on a hybrid run-length encoding which reduces test data storage on the tester. We also introduce modified Bus-invert coding method and scan cell design in scan cell reordering, thus providing increased power saving in scan in operation. Experimental results for ISCAS'89 benchmark circuits show that average power of 96.7% and peak power of 84% are reduced on the average without fault coverage degrading. We have obtained a high reduction of 78.2% on the test data compared the existing compression methods.

• Proceedings of the KIEE Conference
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• 2005.07d
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• pp.3040-3042
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• 2005

During the last several years, interest in broad-band power line communications (PLC) has been grown over medium voltage(MV) power distribution lines as well as low voltage lines. This paper introduces a medium voltage PLC test field that is set up in the suburbs of Euiwang city in Korea. This test field could be used not only for the measurement of communication channel environment but also for internet service. This paper shows the configuration of medium voltage test field with network devices like MV signal coupler and the results of channel environment like noise and impulse response. It also shows the service performance of PLC access network through network management system.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.53 no.12
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• pp.678-684
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• 2004

Automatic reclosing is a typical protection method in power distribution systems for clearing the temporary faults. However, it has a fatal weakness in regards to voltage sags because it produces successive voltage sags. In this paper, we explored successive impact of voltage sag due to the automatic reclosing of power distribution systems. The actual tests of low voltage loads were accomplished for obtaining the susceptibility of voltage sags. The final results of the test yielded power acceptability curves of voltage sag, and the curves were transformed the 3-dimensional CBEMA(Computer Business Equipment Manufacturer Association) format. For the quantitative evaluation of the impact of successive voltage sags, an assessment formulation using the voltage sag contour was proposed. The proposed formulation was tested by using the voltage sag contour data of IEEE standard and the results of the test. Through the case studies, we verified that the proposed method can be effectively used to evaluate the actual impact of successive voltage sans.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.32 no.7
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• pp.105-116
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• 2004

The design of pico-/nano-satellites is particularly challenging due to constraints in mass, volume, power, and surface area. An efficient low-cost picosatellite HAUSAT-1 Electrical Power Subsystem (EPS) is developed to supply the power for various loads during the full mission life. This paper addresses design and analysis results of solar arrays, batteries, power conditioning and distribution units. The component selection, manufacturing and test results are presented by considering appropriate development cost and performance. The simulation results of power system are also illustrated, according to operational modes, through energy balance analysis. Finally, the EFS design feasibility is verified by comparing analysis results with functional and environmental test results at the system and component levels, respectively.