• Journal of the Korean Society for Precision Engineering
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• v.27 no.3
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• pp.118-126
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• 2010

The automated mechanical transmission(AMT) is composed of electronic control management(ECM) and automatic shift gear(ASG). The AMT has advantages which are high efficiency of manual transmissions(MT) and offer operation convenience similar to automatic transmissions(AT). However, it has defects that are the torque gap during gear shift transients and shift time is long. To reduce such defects, it is necessary practically to evaluate error and characteristics as developing simulation model before the control algorithm is applied. In this paper, models are composed of vehicle model and AMT shift control model. Particularly AMT shift control model consists of main clutch management model (MCM) and shift control management model(SCM). The developed models were verified by comparing the simulated and experimental results under the same operational conditions. It can also be used to evaluate shift algorithm.

• Transactions of the Korean Society of Automotive Engineers
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• v.15 no.4
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• pp.41-46
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• 2007

This article deals with the design and prototyping of Shift-By-Wire system for an automatic transmission equipped vehicle. In order to manipulate the shifting action electronically, Shift-By-Wire system consists of an electronic shift lever, an electric shift actuator and position sensors. The shift lever is designed to transform the driver's shifting command into an electric signal; it includes the position sensor using non-contact type hall sensor and an additional shifting switch acting as Tip-tronic. For the design of an electric shifting actuator, we investigated the stroke angles and shifting efforts of the manual control lever in each shifting section. And the position sensor of the shifting actuator is designed by using a potentiometer with an optical encoder. Finally the prototype of Shift-By-Wire system was built in a conventional 2.4L class SUV vehicle, and we performed road tests in order to verify its performance.

• International Journal of Automotive Technology
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• v.7 no.2
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• pp.161-166
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• 2006

This paper presents shift characteristics of a dual clutch transmission(DCT). To obtain the shift force, dynamic models of the DCT are constructed by using MATLAB/Simulink and considering the rotational inertia of every component and the target pre-select time. Dynamic models of the shift and clutch actuators are derived based on the experimental results of the dynamic characteristics test. Based on the dynamic model of the DCT synchronizer, control actuator and vehicle model, a DCT vehicle performance simulator is developed. Using the simulator, the shift force and speed of the relevant shafts are obtained. In addition, the torque and acceleration of actuators are calculated during the shift process by considering the engaging and disengaging dynamics of the two clutches. It is observed from the performance simulator that uninterrupted torque can be transmitted by proper control of the two clutches.

• Smart Structures and Systems
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• v.9 no.2
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• pp.189-206
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• 2012

This paper focuses on the actuation system combined with a piezoelectric transducer and an electric circuit, which leads to a new insight; the electric actuation system is equivalent to mechanical variable-stiffness actuation systems. By controlling the switch in the circuit, the electric status of the piezoelectric transducer is changed, and consequently a variable-stiffness mechanism is achieved on the electric actuator. This proposed actuator features a shift in the equilibrium point of force, while conventional electrically-induced variable-stiffness actuators feature the variation of the stiffness value. We intensively focus on the equilibrium shift in the actuation system, which has been neglected. The stiffness of the variable-stiffness actuator is periodically modulated by controlling the switch, to suppress the vibration of the system in an open-loop way. It is proved that this electric actuator is equivalent to its mechanical counterpart, and that the electrical version has some practical advantages over the mechanical one. Furthermore, another kind of electrically-induced variable-stiffness actuator, using an energy-recycling mechanism is also discussed from the viewpoint of open-loop vibration control. Extensive numerical simulations provide comprehensive assessment on both electrically-induced variable-stiffness actuators employed for open-loop vibration control.

• Journal of the Korean Society for Precision Engineering
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• v.24 no.10
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• pp.75-82
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• 2007

The AMT(Automated Manual Transmission) has been developed by utilizing the auto clutch system and the automatic shift mechanism, to automate the clutch operation and shift operation of the existing MT(Manual Transmission). The use of hydraulic actuator for each actuator of the clutch and gear has realized a reduction of fuel consumption and exhaust emission. In this paper, we develop a simulator for the transmission control system of the AMT using AMESim. The developed simulator can be applied to design the hydraulic select actuator system of an AMT.

• Transactions of the Korean Society of Automotive Engineers
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• v.8 no.1
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• pp.63-71
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• 2000

A shift control algorithm of a newly developed two-speed gear shift system is proposed for electric vehicle applications. The algorithm is formulated according to the motor torque map and optimized to obtain the adequate propulsion characteristics for vehicle. Two speed gear system with shift control algorithm has proved greater efficiencies in terms of energy economy with its simplified hardware and software structures. The gear shifting is designed to be carried out by an actuator and the control signal from a vehicle control unit equipped with $\mu$-processor. The results of performances and efficiency of the algorithm by simulation and vehicle test are described.

• Journal of KSNVE
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• v.7 no.2
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• pp.311-317
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• 1997

In this paper the active vibration control system using a linear oscillatory actuator(LOA) is studied to suppress structural vibration. In the LOA, the AC-power-energized armature generates a shift field in an air gap, which produces a oscillating force to the mover in the magnetic field generated by high density permanent magnets. LOA has relatively simple structure with almost maintenance free, compared with a hydraulic actuator. Performance test of the active vibration control system using a LOA is carried out on a steel test structure under base excitation. From this test, it is confirmed that the acceleration level of the test structure is drastically reduced near the resonant region.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.24 no.11
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• pp.1506-1512
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• 2000

Control of shock may be important in the hydraulic system and necessary to avoid failure and to improve the efficiency of operation. This study addresses the design and use of an orifice to provide the desired control of the hydraulic actuator system. The experimental apparatus is an idealization of an automobile shift system. Control is accomplished by installing three different types of orifices at appropriate locations in the system. Experimental results show that the orifice can be used to obtain the control of shock and control level depends on the orifice size, orifice type, operating pressure and flow rate.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.1282-1285
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• 2004

The high voltage driving system with multi-phase shifter including piezoelectric actuators comprised a driving power unit for outputting the driving power by converting input alternate current into direct current, a frequency shifting unit for supplying the direct current power and shifting or generating a frequency, a high-voltage amplification unit for amplifying the input signal outputted from the driving power unit and the frequency shifting unit into a high-voltage signal, and a phase shifting unit for shifting the phase difference of the amplified signal applied to the high-voltage amplification unit and driving plural piezoelectric actuators sequentially. The results that the operating voltage was stable, the voltage loss ratio was low and the response velocity was fast could be obtained. An experiment on performance of the high voltage driving system with multi-phase shifter designed and manufactured as above described was conducted by using a piezoelectric pump having 3 sheets of round unimorph piezoelectric actuators laminated respectively in a rectangular case. It sucks any fluid by causing the first piezoelectric actuator to shift from the inlet porter side, the phase delay of 60$^{\circ}$ causes the second piezoelectric actuator to begin to shift, and the phase delay of 120$^{\circ}$ causes the third piezoelectric actuator to begin to shift. As a result of measuring each change in the outlet flow rate of the piezoelectric pump, it was shown that the frequency-flow rate characteristic, the voltage-flow characteristic, and the load pressure-flow rate characteristic were improved.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.12
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• pp.1937-1941
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• 2004

We present lateral actuated piezoelectric actuator using U-shaped PZT strip and lever structure for the RF switch application. In the previous study of RF switch, they used horizontal contact switch fabricated by thin film metals. However, thin film metals could not generate large contact force due to low stiffness. In this work, we suggest lateral contact switch which makes large contact force by increasing stiffness. In addition, we use PZT actuator for the high force actuation. Generally actuator using thin film PZT moves to the vertical direction due to the neutral axis shift. Therefore we need lateral motion generation mechanism based on the thin film PZT actuator. In order to increase lateral motion of thin film PZT actuator, we use U-shaped PZT actuator using residual stress control. Also, thin film PZT actuator can generate very small lateral motion of 120${\times}$10$^{-6}$ ${\mu}{\textrm}{m}$/V for d$_{31}$ mode, thus we suggest lever structure to increase stroke amplification. From the experimental study, fabricated PZT actuator shows maximum lateral displacement of 1 ${\mu}{\textrm}{m}$, and break down voltage of the thin film PZT actuator is above 16V.