• 제어로봇시스템학회:학술대회논문집
• /
• 2004.08a
• /
• pp.509-514
• /
• 2004

This paper introduces the modified slip energy recovery system in order to improve its power factor and to reduce harmonics of line current waveforms. Twelve pulse line commutated converter with the chopper type IGBT is applied where the chopper is applied across the DC terminal and the chopped DC is fed to the converter operating as an inverter and then passed through the wye-wye and delta-wye transformer circuit. This scheme leads to be able to adjust the speed of the motor by the duty cycle of the chopper operating in PWM mode. The fuzzy logic controller is also introduced to the modified slip energy recovery system for keeping the motor speed to be constant when the load varies. The experimental results in testing the 0.22 kW wound rotor induction motor from no-load condition to rated condition show the effectiveness of the proposed control scheme.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.11 no.11
• /
• pp.963-968
• /
• 1998

The stress distribution in multilayer piezoelectric ceramic actuators was investigated by Finite element analysis. The y direction stress was concentrated at electrode tip. The y direction maximum stress was decreased to 4.9$\times10^ 7 N/m^2$ with internal electrode gap(a) until 0.4 mm and was not much difference with external electrode thickness(c). The stress distribution with internal layers was almost same and the stress distribution of load condition was higher than that of no load condition The y direction maximum stress increased with the number of layer and saturated at 260 layers. In the case of defective actuator, the stress distribution was disconnected around the defect and larger than that of normal actuator.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.36 no.3
• /
• pp.249-256
• /
• 2000

In order to investigate the effectiveness of methanol, which has high latent heat of evaporation and oxygen contents, for DI diesel engine performance and exhaust emission, the methanol was injected at the suction port of DI diesel engine. The injector used for test was conventional gasoline engine injector and controlled the quantity of methanol per cycle by the power supply controller which designed specially for injector. The results shown that the maximum pressure point was delayed, the value of maximum pressure was decreased, and the concentrations of both NOx and Soot were decreased, as the methanol injection quantity increased, and also the thermal efficiency of engine injected methanol under the high load condition was similar to no methanol injection but under the medium load condition was decreased within the experimental conditions.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1998.06a
• /
• pp.307-310
• /
• 1998

Finite element analysis was investigated on the stress distribution at the 2-D model of piezoelectric ceramic actuators. The y direction maximum stress decreased with a(internal electrode gap) size until 0.4 mm and is not much difference with c(external electrode thickness) size. The stress distribution with internal layers is almost same, and the stress distribution of load condition is higher than that of no load condition. The y direction maximum stress increased exponentially with the number of layer and saturated at 260 layers. In the case of defective actuator, the stress distribution is smaller than that of normal actuator.

• Journal of Wind Energy
• /
• v.2 no.2
• /
• pp.54-60
• /
• 2011

A PMSG in variable speed wind turbine needs to know the position of rotor for vector control. Since the position sensor has the disadvantage in terms of cost, complexity of the system, a sensorless algorithm is needed. The sensorless strategy using the back EMF estimation is used for PMSG Wind Turbine. This algorithm is comparatively easy to implement than other strategies. This paper introduces the application of stable sensorless control for 2MW direct drive PMSG. In order to confirm the sensorless algorithm, the implementation is proceeded using 2MW direct drive PMSG from no-load condition to full-load condition. To drive 2MW PMSG artificially, 2MW PMSG connected PMSG through the mechanical coupling.

• Journal of the Korean Society of Combustion
• /
• v.19 no.3
• /
• pp.1-7
• /
• 2014

Experimental study has been carried out to understand combustion characteristics of a swirl-stabilized premixed gas turbine combustor for power generation. $NO_x$ and CO emissions, extinction limit, pressure loss, and temperature distribution were measured for various operating conditions. Results show that, with increasing inlet air temperature, $NO_x$ is increased due to a higher adiabatic flame temperature while CO is increased or decreased for low or high A/F ratio regime, respectively. depending on the flame location. With decreasing load from the design condition, $NO_x$ is decreased as thermal load is reduced. With further decreasing load, however, $NO_x$ is increased due to a longer residence time. CO is decreased and then increased with decreasing load. Flame extinction limit is extended with increasing inlet air temperature as the recirculation strength is enhanced.

• Proceedings of the Korean Society For Composite Materials Conference
• /
• 2004.04a
• /
• pp.210-213
• /
• 2004

We study the fracture behavior of the lumbar No.4 and No.5 vertebra subjected to posteroanterior (PA) forces, a three dimensional finite element method (FEM). The lumbar spine was modeled 3-dimensionally using commercial software based on the principle of convert stacked two dimensional CT scan images into three dimensional shapes. Determination of the boundary conditions corresponding to actual surgical conditions was not easy, so that the simplified spine beam analyses were performed. The results were used in three dimensional finite element (FE) analysis. This FE analysis, indicates that the fracture loads of the lumbar No.4 and No.5 vertebra are respectively 1550 N and 1500 N. These fracture loads are for static loading, but in actual conditions the load on the lumbar spine varies dynamically. We found that the fracture load of lumbar No.4 vertebra is larger than that of lumbar No.5 vertebra, as a result of the total stress difference by the moment.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2008.11a
• /
• pp.91-98
• /
• 2008

Hypoid gears are widely used in rear drive and 4WD vehicle axles. Investigation of their sensitivity to deflections is one of the most important aspects of their design and optimization procedures. The deflection test is performed in the actual gear mounting using completely processed gear. This test should cover the fun operating range of gear loads from no load to peak load. Under peak load the contact pattern should extend to the tooth boundaries without showing a concentration of the contact pattern at any point on the tooth surface. Transmission error is tested on an axle assembly triaxial real car load condition.

• Proceedings of the KIEE Conference
• /
• 2001.07b
• /
• pp.939-941
• /
• 2001

An efficient control method of ZVS Full-bridge PWM converter with a periodic pulsed-load current is proposed. This novel control method can reduce the switching loss of switches during no load condition. Moreover, by using feed-forwarded load current information this method can obtain better transient dynamics compared to the system with only linear feedback control.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.61 no.11
• /
• pp.1565-1570
• /
• 2012

Nuclear power generation is increasing domestic power supply ratio by lower CO2 emission and fuel prices. Currently, nuclear power generator has been operated with maximum power output. Therefore, nuclear power generator could be no effect to managing the reactive power reserve on power system. The reactive power reserve is calculated to the difference between maximum facility and operation generation capacity of the power system. This paper was proposed that load following of nuclear power is control by using 15-bus power system model. In the simulation result, power system is shown to safety state by operating load following of nuclear power generator. This method has be improved the supplied reliability through economic and efficient operation.