• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.1840-1845
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• 2005

The SoC and digital technology development recently enabled the emergence of information devices and control devices because the SoC present many advantages such as lower power consumption, greater reliability, and lower cost. It is required to use an embedded operating system for building control systems. So far, the Real-Time operating system is widely used to implement a Real-Time system since it meets developer's requirements. However, Real-Time operating systems reveal a lack of standards, expensive development, and license costs. Embedded Linux is able to overcome these disadvantages. In this paper, the implementation of control system platform using Real-Time Embedded Linux is described. As a control system platform, we use XScale of a Soc and build Real-Time control platform using RTAI and Real-Time device driver. Finally, we address the feasibility study of the Real-Time Embedded Linux as a Real-Time operating system for mobile robots.

• Journal of Electrical Engineering and Technology
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• v.10 no.1
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• pp.83-91
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• 2015

This paper presents preventive and emergency control measures for on line transient stability (security) enhancement. For insecure operating state, generation rescheduling based on a real power generation shift factor (RPGSF) is proposed as a preventive control measure to bring the system back to secure operating state. For emergency operating state, two emergency control strategies namely generator shedding and load shedding have been developed. The proposed emergency control strategies are based on voltage magnitudes and rotor trajectories data available through Phasor Measurement Units (PMUs) installed in the systems. The effectiveness of the proposed approach has been investigated on IEEE-39 bus test system under different contingency and fault conditions and application results are presented.

• Journal of Electrical Engineering and Technology
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• v.12 no.1
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• pp.249-255
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• 2017

Efficient operation of induction motor at light loads has been getting wide attention recently because the operating of induction motor at light loads occupies big portion of its operating regions in many applications such as environment friendly vehicle. As one of approaches to improve efficiency, Adaptive Maximum Torque Per Amp (Adaptive MTPA) control for induction motor drives has been proposed to achieve a desired torque with the minimum possible stator current. However, the Adaptive MTPA control was validated only at heavy load where, in general, control scheme tends to perform better than at light loads since the error in measurement of sensors is lower and signal to noise is better. Thus, although the performance of a control scheme is good at rated operating point, its performance at light load is somewhat in doubt in practice. This has led to considerable interest in efficiency of Adaptive MTPA control at light loads. This work experimentally demonstrates performance of Adaptive MTPA control at light loads regardless of rotor resistance variation, thus showing its good performance over all operating conditions.

• Smart Structures and Systems
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• v.19 no.5
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• pp.567-576
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• 2017

Design of piezoelectric energy harvester for a wide operating frequency range is a challenging problem and is currently being investigated by many researchers. Widening the operating frequency is required, as the energy is harvested from ambient source of vibration which consists of spectrum of frequency. This paper presents a new technique to increase the operating frequency range which is achieved by designing a harvester featured by a propped cantilever beam with variable over hang length. The proposed piezoelectric energy harvester is modeled analytically using Euler Bernoulli beam theory and the effectiveness of the harvester is demonstrated through experimentation. The results from analytical model and from experimentation reveal that the proposed energy harvester generates an open circuit output voltage ranging from 36.43 V to 11.94 V for the frequency range of 27.24 Hz to 48.47 Hz. The proposed harvester produces continuously varying output voltage and power in the broadened operating frequency range.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.49 no.1
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• pp.40-50
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• 2013

This study is aimed to find a control factor for the marine casualty of fishing vessel by using the risk quantitative method of marine casualty, and sequentially timed event analysis for the reason finding. The result is that collision, sinking, and capsizing took high risk need to be strongly controlled. And the accident reason and control factors distinguished are as follows. The 82.2% of collided fishing vessels have negligence of look out as a immediate cause, while it was judged that underlying causes were the characteristics of vessels and fishing method, lack of suitable complement, fatigue, the prejudice or ignorance on steering and sailing rules. So the control factors are; firstly needs educational control measures and in terms of systemic control approach expand the range of the certificate of competency more smaller tonnage.

• Journal of Electrical Engineering and Technology
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• v.12 no.2
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• pp.665-673
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• 2017

This paper proposes a field weakening control method for operating an induction motor with a variable DC input voltage condition. In the variable DC voltage condition such as a battery, the field weakening method are required for the maximum output power. The conventional field weakening control methods can be used for operating the induction motor over the rated speed in a constant DC-link voltage condition. However, the conventional methods for operating the motor with the variable DC voltage is not suitable for the maximum output power. To overcome this problem, this paper proposes the optimized field weakening control method to extend the operating range of the induction motor with a rated power in a limited thermal and a wide DC input voltage conditions. The optimized d-axis and q-axis current equations are derived according to the field weakening region I and II to extend the operating region. The experimental results are presented to verify the effectiveness of the proposed method.

• Advances in aircraft and spacecraft science
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• v.5 no.4
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• pp.431-444
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• 2018

Numerical simulations have been conducted to study the unstart/restart characteristics of an over-under turbine-based combined-cycle propulsion system (TBCC) inlet during the inlet transition phase. A dual-solution area exists according to the Kantrowitz theory, in which the inlet states may be different even with the same input parameters. The entire transition process was divided into five stages and the unstart/restart hysteresis loop for each stage was also obtained. These loops construct a hysteresis surface which separates the operating space of the engine into three parts: in which a) inlet can maintain a started state; b) inlet keeps an unstarted state; c) inlet state depends on its initial state. During the transition, the operation of the engine follows a certain order with different backpressures and splitter angles, namely control route, which may result in disparate inlet states. Nine control routes with different backpressures and transition stages were designed to illuminate the route-dependent behavior of the inlet. The control routes operating towards the unstart boundary can make the inlet transit from a started state into an unstarted one. But operating backward the same route cannot make the inlet restart, additional effort should be made.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.1655-1658
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• 2004

In this paper, we design and implement remote servo motor control system with real-time micro embedded operating system. The system, where controller and camera image grabber are mounted, handles control commands transmitted from a remote PC web browser. A hard real-time servo motor driver running on the real-time micro embedded OS and then a digital control application which confirms precise sampling time intervals is constructed. Frame grabber images transmitted from camera are saved in a image data format to view on remote PC web browser.

• Journal of the Semiconductor & Display Technology
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• v.16 no.3
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• pp.25-30
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• 2017

Arago's disk system consists of a speed controller of the DC motor (inner loop controller) and a position controller of the magnetic bar angle (main controller), which are implemented by the design of the PI and PID controller, respectively. First, we analyzed the nonlinear characteristics of the Arago disk system and found the operating point range of three locations as a result. In this paper, a gain scheduler method was applied to guarantee a constant control performance in the range of $0{\sim}130^{\circ}C$, and a structure to change the controller according to the control reference value based on the previously obtained operating points was experimentally implemented. The Distributed Control Systems (DCS) configuration using the Controller Area Network (CAN) was used to verify the proposed method by improving the operational efficiency of the entire experimental system. So, simplicity of the circuit and easy diagnosis were achieved through a single CAN bus communication.

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