• Proceedings of the KIPE Conference
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• 2014.11a
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• pp.83-84
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• 2014

본 논문에서는 센서리스(Sensorless) BLDC 전동기의 출력 토크 능력을 향상시키기 위한 새로운 여자 방식을 제안하였다. 제안된 여자 방식은 기존의 2상 여자 방식에 3상 여자 방식을 혼합하여 12 스텝(Step)으로 운전한다. 제안된 혼합 구동 방식은 전통적인 2상 여자 방식의 6 스텝 운전 방식보다 더 큰 출력 토크를 얻을 수 있으며, 기존의 센서리스 제어에도 적용이 가능하다. 센서리스 BLDC 전동기에 대한 실험을 통해 제안된 기법의 유효성을 확인하였다.

• Proceedings of the KIEE Conference
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• 1997.07a
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• pp.187-191
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• 1997

In this paper, we show that the rotor position of the bifilar-wound hybrid stepping motors for the closed-loop drives is detected by the phase current measurement. We propose an instantaneous phase current equation, which is the function of electrical angle, by the modeling of the stepping motor including motor driving circuits. We also analyze the relationship between phase current and rotor position from the computer simulation results. It is shown that the information about the rotor position is obtained from the phase current amplitude and its derivatives at the instance of ${\pi}/2$ electrical angle of excitation voltage.

• Proceedings of the KIPE Conference
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• 2005.07a
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• pp.240-242
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• 2005

The linear hybrid stepping motors (LHSM) has been widely used due to its simple structure and low cost control. Despite of its attractive features, the conventional LHSM has the multiples of 4th times harmonic reluctance force from excitation current and cogging force from space harmonic of permeance. This paper propose a new LHSM, which the mechanical and electrical phase difference are 45$^{\circ}$. The proposed motor shows a unique ability to deliver low detent force and we propose a closed-loop control scheme to attack the ripple force for high performance applications. An analytical and experimental comparison between conventional and proposed LHSM is evaluated to confirm the effectiveness of the proposed modeling and control scheme.

• KCI Concrete Journal
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• v.11 no.3
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• pp.191-199
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• 1999

A Precast frame system with hybrid beam-column connections was proposed in this study. An analytical study evaluated the system under seismic loadings. Four buildings with different heights were modeled in which each building had three types of joint details (A. B, C). Thus, twelve buildings were examined with variables such as building height and joint detail. Four earthquake records were applied to the buildings as input ground motions. All the records were normalized to the intensity of 0.25g to assess behavior under the same intensity of seismic excitation. All the joint types showed almost identical results except for the Mexico earthquake which was scaled up from 0. 1g to 0.25g. Buildings with the type C joint exhibited the largest deflection for the Mexico earthquake. It was concluded that type B joint could be used in a high seismic zone and the type C joint could possibly be used in the regions of low to medium seismic activity.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.8
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• pp.1400-1406
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• 2016

This paper presents a new adaptive converter control approach for electric motor systems whose voltage source is excited from photovoltaic (PV) power generators. First, an electric model is represented with dynamic states and output velocity of such DC motor systems. We propose a hybrid converter control law in which a state feedback control is applied as an auxiliary control framework. Moreover, control parameter estimation is derived to realize adaptive converter systems for effective control performance against stochastic PV power excitation in practice. We carry out stability analysis for such converter system by using a well-known eigenvalue theory. Lastly, numerical simulation is conducted to test reliability of the proposed converter control approach and prove its superiority in the control point of view.

• Structural Engineering and Mechanics
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• v.77 no.6
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• pp.809-817
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• 2021

In this study, the dynamic behavior of a three-span hybrid continuous arch bridge under vehicle loading is investigated. The natural vibration characteristics of the bridge were analyzed through pulsation test. In the dynamic loading test, the vibrations of the bridge under different truck speeds and different pavement conditions were tested, and time histories of deflection and acceleration of the bridge were measured. Based on the dynamic loading test, the impact coefficient was analyzed. The results indicate that the pavement smoothness had more impacts on the vibration of the bridge than the truck's speed. The vertical damping of the bridge under the excitation of the trucks is larger than the transverse damping. Resonance occurs at the side span of the bridge under a truck at 10 km/h.

• Journal of the Korean Society for Precision Engineering
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• v.32 no.10
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• pp.865-871
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• 2015

This study was conducted in order to develop a finger exoskeleton system using ionic polymer metal composites (IPMCs) as the actuator and sensor in a hybrid structure. To use the IPMC as an actuator producing large force, a first order transfer function was obtained using results from a block force for DC excitation that applied to two IPMCs of 20mm-width, 50mm-length, and 2.4mm thickness together. After which the validation of 200gf control with anti-windup PI controller was confirmed. A 5mm-width, 50mm-length, 0.6mm-thickness of IPMC was also modeled as a sensor for tip displacement. As a result, the IPMC sensor could been utilized as a trigger role for the actuator. Finally, an IPMC sensor and actuator were installed on the joint of a single DOF exoskeleton in the hybrid structure, and test for the control of 40gf of block force and predefined sequence of motion was performed.

• Structural Engineering and Mechanics
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• v.46 no.2
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• pp.153-177
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• 2013

Pendulums can be used as passive vibration control devices in several structures and machines. In the present work, the nonlinear behavior of a pendulum-tower system is studied. The tower is modeled as a bar with variable cross-section with concentrated masses. First, the vibration modes and frequencies of the tower are obtained analytically. The primary structure and absorber together constitute a coupled system which is discretized as a two degrees of freedom nonlinear system, using the normalized eigenfunctions and the Rayleigh-Ritz method. The analysis shows the influence of the geometric nonlinearity of the pendulum absorber on the response of the tower. A parametric analysis also shows that, with an appropriate choice of the absorber parameters, a pendulum can decrease the vibration amplitudes of the tower in the main resonance region. The results also show that the pendulum nonlinearity cannot be neglected in this type of problem, leading to multiplicity of solutions, dynamic jumps and instability. In order to improve the effectiveness of the control during the transient response, a hybrid control system is suggested. The added control force is implemented as a non-linear variable stiffness device based on position and velocity feedback. The obtained results show that this strategy of nonlinear control is attractive, has a good potential and can be used to minimize the response of slender structures under various types of excitation.

• The Transactions of the Korean Institute of Power Electronics
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• v.10 no.6
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• pp.527-533
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• 2005

The linear hybrid stepping motors (LHSM) has been widely used due to its simple structure and low cost control. Despite of its attractive features, the conventional LHSM has the multiples of 4th times harmonic reluctance force from excitation current and cogging force from space harmonic of permeance. This paper propose a new LHSM, which the mechanical and electrical phase difference are $45^{\circ}$. The proposed motor shows a unique ability to deliver low detent force and we propose a closed-loop control scheme to attack the ripple force for high performance applications. An analytical and experimental comparison between conventional and proposed LHSM is evaluated to confirm the effectiveness of the proposed modeling and control scheme.

• Advances in concrete construction
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• v.8 no.1
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• pp.9-19
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• 2019

This paper describes an experimental investigation on hybrid fiber reinforced concrete (HYFRC) beams. And the main aim of this present paper is to examine the dynamic characteristics and damage evaluation of undamaged and damaged HYFRC beams under free-free constraints. In this experimental work, totally four RC beams were cast and analyzed in order to evaluate the dynamic behavior as well as static load behavior of HYFRCs. Hybrid fiber reinforced concrete beams have been cast by incorporating two different fibers such as steel and polypropylene (PP). Damage of HYFRC beams was obtained by cracking of concrete for one of the beams in each set under four-point bending tests with different percentage variation of damage levels as 50%, 70% and 90% of maximum ultimate load. And the main dynamic characteristics such as damping, fundamental natural frequencies, mode shapes and frequency response function at each and every damage level has been assessed by means of non-destructive technique (NDT) with hammer excitation. The fundamental natural frequency and damping values obtained through dynamic tests for HYFRC beams were compared with control (reference) RC beam at each level of damage which has been acquired through static tests. The static experimental test results emphasize that the HYFRC beam has attained higher ultimate load as compared with control reinforced concrete beam.