• Journal of the Korean Society for Precision Engineering
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• v.15 no.6
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• pp.15-21
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• 1998

Mostly a ride comfort and handling performance of vehicle is influenced by dynamic behavior control of vehicle. We are focusing on development of a semi-intelligent suspension system with continuously variable damper(HS-SH type). only using absolute velocity of sprung mass without using the relative velocity besides having lower system prices and a little energy requirement. In this paper, the system is realized in consideration to control strategy (sky-hook control, hybrid filter, etc.) and has been proved to have improvement of behavior control of vehicle by quarter car and Vehicle test, respectively.

• Proceedings of the KIEE Conference
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• 1995.11a
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• pp.287-289
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• 1995

In this paper, We applied the $\mu$-stepping method on the Phase Excitation Sequence of Hybrid type LPM. Linear Pulse Motor can opeate in an open loop control as an effective positioning actuator. PWM driver was used for low power loss and automatically adjusted voltage at rate current. Finally we find that through the position-velocity for timing Triangular and Trapezoidal Profile are very affected by velocity and acceleration parameter.

• Proceedings of the KIEE Conference
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• 1999.07b
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• pp.501-503
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• 1999

In this paper, the design method of a hybrid fuzzy controller with an optimal auto-tuning method is proposed. The conventional PID controller becomes so sensitive to the control environments and the change of parameters that the efficiency of its utility for the complex and nonlinear plant has been questioned in transient state. In this paper, first, a hybrid fuzzy logic controller(HFLC) is proposed. The control input of the system in the HFLC is a convex combination by a fuzzy variable of the FLC's output in transient state and the PID's output in steady state. Second, a powerful auto-tuning algorithm is presented to automatically improve the Performance of controller, utilizing the improved complex method and the genetic algorithm. The algorithm estimates automatically the optimal values of scaling factors and PID coefficients. Controllers are applied to the plants with time-delay and the DC servo motor Computer simulations are conducted at the step input and the system performances are evaluated in the ITAE.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.41 no.1
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• pp.40-47
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• 2013

The similarity in internal flow of solid and hybrid rocket suggests that hybrid rocket combustion can be susceptible to instability due to vortex sheddings and their interaction. This study focuses on the evolution of interaction of vortex generated in pre-chamber with other types of vortex in the combustor and the change of combustion characteristics. Baseline and other results tested with disks show that there are five different frequency bands appeared in spectral domain. These include a frequency with thermal lag of solid fuel, vortex shedding due to obstacles such as forward, backward facing step and wall vortices near surface. The comparison of frequency behavior in the cases with disk 1 and 3 reveals that vortex shedding generated in pre-chamber can interact with other types of vortex shedding at a certain condition. The frequency of Helmholtz mode is one of candidates resulting to a resonance when it was excited by other types of oscillation even if this mode was not discernable in baseline test. This selective mechanism of resonance may explain the reason why non-linear combustion instability occurs in hybrid rocket combustion.

• Journal of the Korea Convergence Society
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• v.11 no.11
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• pp.203-209
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• 2020

A hybrid mount featuring rubber element and piezoelectric actuator is devised to reduce vibration when starting a vehicle engine. As a first step, a passive mount adopting rubber element is manufactured and its dynamic characteristics are experimentally evaluated. After evaluating dynamic characteristics of the manufactured inertial piezoelectric actuator, the proposed hybrid mount is then established by integrating the piezoelectric actuator with the rubber element for performance improvement at non-resonant high frequencies. A mathematical model of the established active vibration control system is formulated and expressed in the state space form. Subsequently, sliding mode controller (SMC) is designed to attenuate the vibration transmitted from the base excitation. Finally, control performances of the proposed hybrid mount are evaluated such as transmissibility in frequency domain and time responses.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.18 no.1
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• pp.36-41
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• 2009

This paper presents the development of a micro punching system with modified cymbal mechanism. To realize the micro punching, we introduced the hybrid system with a macro moving part and micro punching part. The macro moving part consists of a ball screw, a linear guide and the micro step motor and micro punching part includes the PZT actuators and displacement amplification device with modified cymbal mechanism. The PZT actuator is capable of producing very large force, but they provide only limited displacements which are several micro meters. Thus the displacement amplification device is necessary to make those actuators more efficient and useful. For this purpose, a cymbal mechanism in series is proposed. The finite element method was used to design the cymbal mechanism and to analyze the mode shape of the one. The displacement and mode shape error between the FEM results and experiments are within 10%. A considerable design effort has been focused on optimizing the flexure hinge to increase the output displacement and punching force.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.1
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• pp.29-36
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• 2014

Hybrid rocket displays many different low frequency pressure oscillations during combustion. Thermal lag between solid and gas phase is the primary mechanism to trigger low frequency pressure oscillations of around 10Hz, and Helmholtz or $L^*$ mode also produces other types of low frequency oscillations above 10 Hz which is associated with the change in combustion volume. Since the flow characteristics in hybrid rocket is very similar to those in solid rocket combustion, it is not surprising to observe similar pressure oscillation behaviors. Experimental test shows that combustion pressure suddenly turns into to a big amplitude oscillation around 10Hz then followed by returning to an original pressure level after a short period combustion. Further investigations show that this instability is independent of the change in O/F ratio at all. One of the possible candidates is the vortex shedding dynamics over the backward step in the post combustion chamber. It is required to investigate the low frequency oscillation mechanism in the future study.

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.760-762
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• 2000

Hybrid type LPM can be widely applied in the precise position controlled devic because precise linear motion can be directly obtained by the simple control circuit without backlash in the rotary-type stepping motor. Also, LPM can increase the Position resolution, which was limited by mechanical manufacturing limit and characteristic of magnetic material. using micro-step drive method to decrease the noise and vibration further. Especially, Double-side LPM may be replaced the solenoid as the valve driving device without difficulty and give full play to control the valve accurately. Hence, In this paper, magnetic circuit of double-side LPM was confirmed and static thrust force curve according to the relative displacement between stator and mover, was analyzed by the two dimensional finite element method. From this results, we can suppose the excitation current to be controlled optimally.

• Proceedings of the KIPE Conference
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• 2017.07a
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• pp.409-410
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• 2017

마이크로 스텝제어를 적용한 스텝 모터는 가격대비 성능이 다른 전동기에 비하여 우수하기 때문에 다양한 산업분야에 광범위하게 사용된다. 큰 감속비를 갖는 응용분야에서는 1000 [rpm]이상의 고속운전이 필요한 경우가 빈번하게 발생하며 이 경우 마이크로 스텝제어가 현실적으로 불가능하다. 본 논문에서는 고속운전이 가능한 고정밀 위치제어용 스텝 모터 제어 알고리즘에 대한 연구를 진행한다. S커브 형태의 위치 프로파일을 적용한 고성능 위치 제어를 위해 마이크로 스텝제어를 적용하여 위치제어를 수행하며 고속 이동시에는 기본 스텝제어로 제어방식을 절환하는 하이브리드 운전 기법을 제안한다.

• Journal of Electrical Engineering and Technology
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• v.8 no.4
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• pp.911-919
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• 2013

This paper reports the development of test bed with the energy recovering technique using two-step boost converter. The device is utilized for LDC aging test of Hyundai Motor's LPI AVANTE HEV in mass production. The developed power recycle type test bed is designed as 1.5 kW class to test up to the maximum load power of LDC and is also designed to supply scant power supply up to 500 W after power recycle. The theoretical design analysis and operational characteristics analysis results of test bed are reported, and its practicality and reliability are verified through the test result. Also, the finally developed test bed confirms approximately 79~85 % energy saving effect compared to the usual traditional aging test system.