• Proceedings of the KIEE Conference
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• 1998.07f
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• pp.2142-2144
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• 1998

We proposed the speed control of the SLIM(Single-sided Linear Induction Motor) for conveyance system by the decoupled thrust control. The voltage equations of SLIM are expressed on the suitable $\alpha-\beta$ axis by the proposed equivalent circuit, which can analyze the characteristics of the thrust and the normal force and so on. These control methods, which are the slip angular frequency control and the decoupling control for the thrust and normal force by analyzing these parameters can be successfully driven without interfering of each axis. These results exemplified the linear drive of SLIM with the reference value.

• Journal of Institute of Control, Robotics and Systems
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• v.19 no.10
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• pp.873-878
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• 2013

An EOTS (Electro-Optical Tracking System) provides stabilized images while tracking a moving target. This paper presents a novel concept of driving the outer gimbal first for improving the maneuverability of an EOTS, contrary to the conventional inner gimbal mode. It has the advantages of faster positioning performance and stable operation in Nadir-point. Analysis of frequency responses reveal that the present scheme results in a wider control bandwidth and larger gain margin, compared to those of the previous one. The actual experimental results confirm that the maneuvering is stable although the input command has a large angular acceleration.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.7 no.1
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• pp.5-8
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• 1977

The author has observed 906 full mouth roentgenograms in Korean young man who had the impacted and supernumerary teeth. Impacted and supernumerary teeth were analysed upon several items, such as incidences and positions in the dental arch. The result were as follows; 1. The incidences of impacted teeth were 59.05% and the ratio of upper jaw to lower one was 1:3. 2. The frequency of the supernumerary teeth were 5.52% and the ratio of maxilla to mandible was 49:1. 3. No significant differences between right and left side in both jaws, but incidence rate of the supernumerary teeth was 74% in the maxillary central incisor area. 4. The positions of impacted and supernumerary teeth were vertical and inverted shapes in maxilla, whereas horizontal and mesio-angular forms in mandible.

• Proceedings of the KIEE Conference
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• 1998.11b
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• pp.685-688
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• 1998

In this research project, two aspects of small signal stability are studied: improvement in Hessenberg method to compute the dominant electromechanical oscillation modes and siting FACTS devices to damp the low frequency oscillation. Fourier transform of transient stability simulation results identifies the frequencies of the dominant oscillation modes accurately. Inverse transformation of the state matrix with complex shift equal to the angular speed determined by Fourier transform enhances the ability of Hessenberg method to compute the dominant modes with good selectivity and small size of Hessenberg matrix. Any specified convergence tolerance is achieved using the iterative scheme of Hessenberg method. Siting FACTS devices such as SVC, STACOM, TCSC, TCPR and UPFC has been studied using the eigen-sensitivity theory of augmented matrix. Application results of the improved Hessenberg method and eigen-sensitivity to New England 10-machine 39-bus and KEPCO systems are presented.

• Journal of Institute of Control, Robotics and Systems
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• v.12 no.6
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• pp.608-613
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• 2006

Any input acceleration that bends RLG dithering axis causes flexure error, which is a source of the noncommutative error that can not be compensated by simply using integrated gyro sensor output. This paper introduces noncommutative error equations that define attitude errors caused by flexure errors. In this paper, flexure error is classified as sensor level error if the sensing axis coincides with the dithering axis and as system level error if the two axes do not coincide. The relationship between gyro output and the rotation vector is introduced and is used to define the coordinate transformation matrix and angular motion. Equations are derived for both sensor level and system level flexure error analysis. These equations show that RLG based INS attitude error caused by flexure is directly proportional to time, amount of input acceleration and the dynamic frequency of the vehicle.

• Proceedings of the KIEE Conference
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• 2000.11b
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• pp.372-374
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• 2000

This paper presents a study on the indirect FOC (field oriented control) of induction motor using TMS320F240. This DSP has become possible to design and implement a highly efficient and accurate AC induction drive control. This paper describes a pulse width modulator based on the voltage space vectors technique that accepts voltage demands in dq coordinates and generates three-phase PWM waveforms to drive a variable frequency voltage-source inverter. The Current Model lock is added to generate the rotor flux angular speed.

• Proceedings of the KIEE Conference
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• 1998.11a
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• pp.365-368
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• 1998

In this research project two aspects of small signal stability are studied: improvement in Hessenberg method to compute the dominant electromechanical oscillation modes and siting FACTS devices to damp the low frequency oscillation. Fourier transform of transient stability simulation results identifies the frequencies of the dominant oscillation modes accurately. Inverse transformation of the state matrix with complex shift equal to the angular speed determined by Fourier transform enhances the ability of Hessenberg method to compute the dominant modes with good selectivity and small size of Hessenberg matrix. Any specified convergence tolerance is achieved using the iterative scheme of Hessenberg method. Siting FACTS devices such as SVC, STACOM, TCSC, TCPR and UPFC has been studied using the eigen-sensitivity theory of augmented matrix. Application results of the improved Hessenberg method and eigen-sensitivity to New England 10-machine 39-bus and KEPCO systems are presented.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11b
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• pp.609-616
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• 2001

The vibrational characteristics of nonuniform circular rods have been studied theoretically and experimentally in this paper. The differential equation of torsional motion expressed in terms of the angular displacement has been solved exactly and approximately for a stepped circular rod and for a conically-tapered rod. Solutions of the boundary-value problem have yielded the natural frequencies, mode shapes and forced responses of the rods. The theoretical solutions of forced response have been verified by comparing them with experimental ones.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.11a
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• pp.279-282
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• 2004

In this paper, A new type of piezoelectric step motor using piezoelectric torsional actuator and a pair of one-way clutch bearing is designed, manufactured and tested. The torsional actuator consists of 16-polygonal tube that can produce angular displacement using shear mode of piezoceramic. One-way clutch bearing convert oscillation of torsional actuator into continuous rotation. After performance testing of torsional actuator, the optimum condition for driving motor is investigated in terms of wave shape, excitation frequency and electrical field. The performance of the motor is experimentally evaluated. As a result, square wave has larger rotation speed than sin wave, and the maximum rotation speed of 57 rpm is measured at 3850 Hz and 100V/mm.

• Earthquakes and Structures
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• v.10 no.3
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• pp.681-697
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• 2016

The model of two-temperature magneto-thermoelasticity for a non-simple variable-thermal-conductivity infinitely-long solid cylinder is established. The present cylinder is made of an isotropic homogeneous thermoelastic material and its bounding plane is traction-free and subjected to a time-dependent temperature. An exact solution is firstly obtained in Laplace transform space to obtain the displacement, incremental temperature, and thermal stresses. The inversion of Laplace transforms has been carried out numerically since the response is of more interest in the transient state. A detailed analysis of the effects of phase-lags, an angular frequency of thermal vibration and the variability of thermal conductivity parameter on the field quantities is presented.