• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.1060-1065
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• 2003

This paper contributes to development of a new chip mounting head system for flip chip. Recently, the LDM(Linear DC Motor) has been widely used, because it has particular merits than the rotary type motors. In this paper, we proposed a macro/micro positioning system for force control of a chip mounting system. In the proposed macro/micro system, the macro actuator provide the system with a gross motion while the micro device yields fine tuned motion to reduce the harmful impact force that occurs between very small sized electronic parts and PCB surface. In order to prove the effectiveness of the proposed macro/micro chip mounting system, we compared the proposed chip mounting head with the conventional chip mounting head equipped with a macro actuator only. A series of experiments were executed under the mounting conditions of various access velocities and PCB stiffness. As a result of this study, a satisfactory voice coil actuator as the micro actuator has been developed, and its performance meet well the specifications desired for the design of the chip mounting head system and show good correspondence between theoretical analysis and experimental results.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.05a
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• pp.255-258
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• 2002

Dental chewing masticator, which is an essential device for evaluating the wear of dental resin and the interfacial failure between the filling resin and enamel of tooth used in conservative dentistry, was developed. This dental chewing masticator mimics the chewing motion and loading by adapting DC motor and rotary cam system. Chewing loading of 49N was imposed by computer-displacement control, loadcell, LM guide, and spring system. Extracted tooth was fixed into a holding jig, and this jig was mounted with rubber pad on the $15^{\circ}$inclined surface to consider the lateral movement of periodontal ligament. A water bath was installed for providing the environment of inside mouth and for circulating the $5^{\circ}C-55^{\circ}C$ water to evaluate the effect of hydrothermal cycling on the damage of resin filled teeth during long-term chewing activity.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.826-831
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• 2004

Recently, studies have been carried out to develop unmanned Micro Air Vehicles(MAVs) that can search and monitor inside buildings during urban warfare or rescue operations in hazardous environments. However, existing fixed-wing and rotary-wing MAVs cannot travel at extremely low or high speeds, hover in place, or change directions instantly. This has lead researches to search for other flight methods that could overcome those drawbacks. Insect flight principles and its applications to MAVs are being studied as an alternative flight method. To take flight, insects flap and rotate their wings. These wing motions allow for high maneuverability flight such as hovering, vertical take off and landing, and quick acceleration and deceleration. This paper proposes a method for designing a mechanism that reproduces hovering insect flight, the basis for all other forms of insect flight. The design of a mechanism that can reproduce the motion that causes maximum lift is proposed, the required specifications are calculated, and a method for reproducing hovering insect flight with a single motor is presented. Also, feasibility of the design was confirmed by simulation.

• Journal of Electrical Engineering and Technology
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• v.12 no.4
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• pp.1471-1483
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• 2017

The low-frequency characteristics of four-switch three-phase (FSTP) inverter are investigated in this paper. Firstly, a general space vector pulse width modulation (SVPWM) directly involved the neutral point voltage of DC-link is proposed, where no sector identifications and trigonometric function calculations are needed. Subsequently, to suppress the DC offset in the neutral point voltage, the relationship between the neutral point voltage and the ${\beta}-axis$ component of the load current is derived, and then a new neutral point voltage control scheme is proposed where no low pass filter is adopted. Finally, the relationship between the load power factor and the maximum linear modulation index of the FSTP inverter is revealed. Since the operational region for the FSTP inverter in low frequency is reduced by the enlarged amplitude of the neutral point voltage, a linear modulation range enlargement scheme is proposed. A permanent magnet synchronous motor with preset rotary speed serves as the low-frequency load of the FSTP inverter. Experimental results verify that the new neutral point voltage control scheme is effective in the deviation suppression of the neutral point voltage, and the proposed scheme is able to provide a larger linear operational region in low frequency.

• Journal of the Korean Society of Marine Environment & Safety
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• v.13 no.4
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• pp.113-117
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• 2007

The study was performed on the development of system in which the bead width can be controlled. In order to control the bead width, we designed the automatic seam tracking device by attaching the probe type strain gauge sensor, motor driving slide and encoder to check the moving distance, and interface card connected MCU(80Cl96KC) upside the speed controllable carriage. Seam tracking experiments were done by changing the bead width. We compared and analyzed the sampling data which were obtained by output voltage of strain gauge sensor and rotary encoder pulse every 50ms.

• Smart Structures and Systems
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• v.13 no.3
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• pp.419-434
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• 2014

In this paper, the electromagnetic damper (EMD), which is composed of a permanent-magnet rotary DC motor, a ball screw and a nut, is considered to be analyzed as a semi-active damper. The main objective pursued in the paper is to study the two degrees of freedom (DOF) model of the semi-active electromagnetic suspension system (SAEMSS) performance and energy regeneration controlled by on-off and continuous damping control strategies. The nonlinear equations of the SAEMSS must therefore be extracted. The effects of the EMD characteristics on ride comfort, handling performance and road holding for the passive electromagnetic suspension system (PEMSS) are first analyzed and damping control strategies effects on the SAEMSS performance and energy regeneration are investigated next. The results obtained from the simulation show that the SAEMSS provides better performance and more energy regeneration than the PEMSS. Moreover, the results reveal that the on-off hybrid control strategy leads to better performance in comparison with the continuous skyhook control strategy, however, the energy regeneration of the continuous skyhook control strategy is more than that of the on-off hybrid control strategy (except for on-off skyhook control strategy).

• 연구논문집
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• s.34
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• pp.39-46
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• 2004

The compressors in the air conditioner have the role of the pressurization and circulation of the refrigerant. The hermetic reciprocating compressors driven by rotary motor have been used for the air conditioner. The linear compressor has very simple structure and enhancement in the efficiency in comparison to that of conventional reciprocating compressor. The linear compressors are widely used for the small cryogenic refrigerator (below 1 kW), such as the Stirling refrigerator and pulse tube refrigerator. In the cryogenic application, the pressure ratio of the linear compressor is below 1.5, but the linear compressor for the air conditioner should overcome the high pressure ratio and the large pressure difference between the each sides of the piston. The resonance characteristics of the linear compressor has the significant impacts on the power consumption. To minimize the power consumption, the linear compressor should be operated at the resonance point. In the resonance characteristics, the role of the mechanical and gas spring should be considered. In present study, the cycle of the analysis of the vapor compression refrigeration cycle with the different refrigerants (R134a, R4l0a, R600a) and the designs of the linear compressor are performed. The effects of the stiffness of the mechanical spring on the electromagnetic forces would be discussed. Finally, the results show the design specification of the linear compressor for the air conditioner.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.05b
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• pp.53-56
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• 2000

Piezoelectric ceramics can provide electro-mechanical transduction with high stresses but low displacement. To obtain larger displacements, several mechanical amplifying structures have been used. High alternating displacements can be obtained using resonant structure. In this paper, we designed a bolt-tightened Langevin type ultrasonic vibrator whose resonant frequency is 50[kHz] and ceramics are multilayered. FEM(Finite Element Methode) was employed to calculate. the resonant frequencies and maximum displacements of designed vibrators. The designed resonant frequency and computer calculated frequencies were coincided. When input voltages were increased, the maximum displacements also rose. As AC voltage was applied, the maximum displacement were shown sinusoidal changes. Terminal input admittance over a frequency range spanning the resonant frequency were calculated. ANSYS was used to find resonant frequencies and calculate displacements of vibrators.

• Journal of Institute of Control, Robotics and Systems
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• v.16 no.4
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• pp.353-360
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• 2010

A skid-steering method which applied to the various mobile robot platforms currently shows its effectiveness in the specified field areas and purposes. This system contains however, several problems of its intrinsic properties such as slippages occurred by different moving direction between vehicle's driving and wheel's rotary and difficulties of driving performance control and so on. This paper deals with the suggestion of suitable control algorithm for 6WD/6WS skid steering wheeled vehicle and verified its feasibility by analyzing the behavior of 6WD/6WS skid-steered wheeled vehicle model and by applying the engineering analytical method to the considered mobile platform. The Performance of vehicle model is evaluated by using slip mode control to follow the steering input and, as a future work, this control algorithm could be applied to real 6WD/6WS in-wheel drive type vehicle finally.

• Journal of Advanced Marine Engineering and Technology
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• v.30 no.3
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• pp.438-443
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• 2006

The probe type sensor using strain gauges was used to track a container box's seam in this paper. A strain gauge has a property which the specific resistance is changed by varying of the sectional area and length when tensile and compressive stresses are generated at the strain gauge. We designed the automatic seam tracking device by attaching the probe type strain gauge sensor, motor driving slide, encorder to check the moving distance and interface card connected MPU upside the speed controllable carriage. The folded work piece for a container box is made to examine whether the device can track the seam automatically or not. Seam tracking experiments were done by changing the carriage moving speed at 300. 400. 500. 600[mm/min] each as the voltage of side track was 2.5[V]. We compared and analyzed the sampling data which is obtained by output voltage of strain gauge sensor and rotary encorder pulse every 100 [m/s]. The welding experiments were performed by using $CO_2$ welding machine about the carriage moving speed that has good seam tracking condition in the seam tracking experiments above. And we compared the seam tracking status.