• Journal of Power Electronics
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• v.4 no.2
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• pp.96-101
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• 2004

This paper presents an application of SRM drive for LSEV(Low Speed Electric Vehicle). In this paper, a 5〔㎾〕 SRM for a traction of a LSEV is to design and investigate the characteristics of the drive system. The main design parameters and control strategy are given. In the control method, a current control, for the soft-starting technique at a starting operation, is adopted. In the high speed range, an angle control technique is implemented, for a high efficiency drive of SRM. Some experimental tests are executed to find the drive performances.

• Journal of Power Electronics
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• v.19 no.5
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• pp.1193-1202
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• 2019

A SMPMSM drive system is a typical nonlinear system with time-varying parameters and unmodeled dynamics. The speed outer loop and current inner loop control structures are coupled and coexist with various disturbances, which makes the speed control of SMPMSM drive systems challenging. First, an ultra-local model of a PMSM driving system is established online based on the algebraic estimation method of model-free control. Second, based on the backstepping control framework, model-free adaptive integral backstepping (MF-AIB) control is proposed. This scheme is applied to the permanent magnet synchronous motor (PMSM) drive system of an electric vehicle for the first time. The validity of the proposed control scheme is verified by system simulations and experimental results obtained from a SMPMSM drive system bench test.

• Transactions of the Korean Society of Automotive Engineers
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• v.19 no.1
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• pp.17-24
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• 2011

TMED(Transmission Mounted Electric Device) parallel hybrid configuration can realize EV(Electric Vehicle) mode by disengaging the clutch between an engine and a transmission-mounted motor to improve efficiencies of low load driving and regenerative braking. In the EV mode, however, jerk can be induced since there are insufficient damping elements in the drive-train. Though the jerk gives demoralizing influence upon driving comport, adding a physical damper is not applicable due to constraints of the layout. This study suggests the jerk reduction control, composed of active damping method and torque profiling method, to suppress the jerk without hardware modification. The former method creates a virtual damper by generating absorbing torque in the opposite direction of the oscillation. The latter method reduces impulse on the mated gear teeth of the drive-train by limiting the gradient of traction torque when the direction of the torque is reversed. To validate the effectiveness of the suggested strategy, a series of vehicle tests are carried out and it is observed that the amplitude of the oscillation can be reduced by up to 83%.

• The Transactions of the Korean Institute of Power Electronics
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• v.5 no.1
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• pp.95-103
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• 2000

In this paper, a novel indirect rotor position sensing method is proposed to improve the performClIlce of sensorless drive of brushless DC motors. The fast mode change to the sensorless operation is difficult in the existing indirect rotor position sensing methods because a precise rotor position can not be obtained when an excessive input is applied to the drive during synchronous operation mode. To cope with this problem, the relationship between terminal voltage and back-emf waveform is analyzed in this paper, also a novel indirect position sensing method which can detect a precise rotor position at low speed range is proposed. The effectiveness of the proposed method is verified through the experimental results.

• Proceedings of the KIEE Conference
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• 2005.10b
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• pp.270-272
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• 2005

In this paper, we proposed a new method detecting actions of some components driven by the coil excitation. Nuclear power reactors are typically controlled by the movement of several neutron-absorbing control rods into or out of the reactor core. For moving control rods, we use an electromagnetic-jack-typed mechanism, which is called Control Rod Drive Mechanism. This mechanism moves control rods by the step composed of sequential actions of components. In case any mechanical problems happen in the mechanism, the orders for the control rod movement from the higher system cannot be performed properly. This abnormal state must be monitored and the sequential actions of the components can be the monitoring target. The actions of components generate some deviations in the profiles of the currents flowing into the coils in the mechanism. We focused on this phenomena and devised a new method of detecting the actions of the components in Control Rod Drive Mechanism by using the wavelet transform for observing the current profile.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.11
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• pp.2004-2009
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• 2007

A new high-speed drive method for the plasma display panel is proposed. In this method, the address period is inserted for the rest period of the sustain pulses and the priming pulse is applied on the entire panel at the same time overlapping with the sustain period. The ramp shaped priming pulse can be made with a simple drive circuit in this technology and the stable sustain discharge can be induced even by a narrow scan pulse in help of the space charge generated from the address discharge. From the experiments, it is ascertained that the priming pulse hardly influences the sustain discharge. Moreover, the voltage margin of the sustain discharge is almost constant though that of the address discharge broadens with narrowing the scan pulse width. And, if the time interval between the scan pulse and the sustain pulse is within $6{\mu}s$, the voltage margin of the address and the sustain discharges are unaffected though the applied position of the scan pulse is changed. High-speed driving with the address pulse of $0.7{\mu}s$ width was achieved and the address voltage margin of 20V and the sustain voltage margin of 10V were obtained.

• The Journal of the Korea institute of electronic communication sciences
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• v.16 no.1
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• pp.109-116
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• 2021

Since RDF (Resource Description Framework) triples are modeled as graph, we cannot directly adopt existing solutions in relational databases and XML technology. In order to store, index, and query Linked Data more efficiently, we propose a convergence indexing method combined R*-tree and K-dimensional trees. This method uses a hybrid storage system based on HDD (Hard Disk Drive) and SSD (Solid State Drive) devices, and a separated filter and refinement index structure to filter unnecessary data and further refine the immediate result. We perform performance comparisons based on three standard join retrieval algorithms. The experimental results demonstrate that our method has achieved remarkable performance compared to other existing methods such as Quad and Darq.

• Journal of Power System Engineering
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• v.12 no.2
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• pp.41-47
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• 2008

This article deals with the stress analysis of the friction drive, which transmits the power via the rolling resistance on the contract area between the two rotating bodies. On the contact area, friction drives are normally involved with shear stress due to the transmitted force, as well as normal stress. Thus the stress analysis including the shear stress is necessary for the design of the friction drive. Hertzian results can be used to estimate the normal stress distribution and elastic deflection of the contact area, although the shear stress distribution is not well defined. In order to investigate the shear stress distribution and its effects in a friction drive, we have performed the stress analysis of the spherical continuously variable transmission(CVT) using finite element method. The spherical CVT is one of friction drives, which is used in small power applications. The numerical results show that the normal stress distribution is not affected by the transmitted shear force, and the maximal shear stress is increased in small amount along with the shear force.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11b
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• pp.570-575
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• 2002

Servo performance of a disk drive is greatly affected by the mechanical resonance frequencies of the head gimbal assembly (HSA). It is important factor to allow broader bandwidths for servo system in improving overall drive performance. In this paper, an optimal design for ODD suspension is attempted to increase resonance frequencies in tracking direction. Initial model was designed and the design parameter was defined to the model. The mode frequency variation for the change of design parameter was observed by modal analysis using the finite element method(FEM). The sensitivity matrix was calculated from the observed data and so through sensitivity analysis, an optimized ODD suspension was designed to have the higher resonant frequency than the initial model.

• 제어로봇시스템학회:학술대회논문집
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• 1988.10b
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• pp.1014-1017
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• 1988

Direct-drive robots have excellent features including no backlash, small friction, and high mechanical stiffness. However, dynamic coupling among joints as well as nonlinear effects become more prominent than traditional robots with reducers. Another critical issue is that the robot becomes more sensitive to the change of load. In this paper, we develop a simple current feedback scheme for reducing the influence of dynamic coupling and load sensitivity on the direct-drive robots. The method is implemented on a 2 d.o.f. planar direct-drive robot. Then the validity of the method is demonstrated through experiments.