Jong-Sub Lee

Characteristics of Disk-type Linear Ultrasonic Motor for Application to x-y Stage

In this paper, a disk-type ultrasonic motor using a combination of radial and bending vibration modes is newly designed and fabricated. The characteristics of the test motor are also measured. By means of traveling elastic wave induced at the surface of circumference of the elastic disk, a steel bar in contact with the surface of circumference of the elastic disk bonded onto the piezoelectric ceramic disks is driven in both directions by changing the sine and cosine voltage inputs. The stator of the motor is composed of two sheets of piezoelectric ceramic disks to bond onto both surfaces of an elastic disk, respectively. As a result, the diameter of the elastic body is increased and the resonant frequency is decreased. The resonant frequency of the stator is about 92 ㎑, which is composed with piezoelectric ceramic disks of 28 ㎜ in diameter and 2 ㎜ in thickness, and an elastic body of 32 ㎜ in diameter and 2 ㎜ in thickness. A driving voltage of 20 Vpp produces 200 rpm with a torque of 1 Nm and an efficiency of about 10 %.

Characteristics of π-shaped Ultrasonic Motor

In this paper, the design and characteristics of a Π-shaped ultrasonic motor that is applicable to optical zoom operation of a lens system for mobile phones are investigated. Its design and simulation of performances are carried out by FEM (finite element method) commercial software. As a simulation result, by applying voltage with single phase, a combined vibration is produced at the surface of a stator arm. A prototype of the motor is fabricated and its outer size is 8*4*2 ㎣ including the cylindrical steel rod of 2 ㎜ in diameter as the rotor. The motor exhibits a maximum speed of 500 rpm and a power consumption of 0.3 W when driven at 20 Vpp and 64 ㎑.

The Design and Characterization of Ultrasonic Motor for Optical Zooming of Camera in Mobile Phones

In this paper, the design and characteristics of a p-shaped ultrasonic motor which is applicable to optical zoom operation of lens system for mobile phone are investigated. Its design and simulation of performances are carried out by FEM (finite element method) commercial software. As a simulation result, by applying voltage with single phase, a combined vibration is produced at the surface of an arm of stator. The prototype of motor is fabricated and its outer size is 8 * 4 * 2 mm3 including the cylindrical steel rod of 2 mm in diameter as rotor. The motor exhibits a maximum speed of 500 rpm and a power consumption of 0.3 W when driven at 20 Vpp and 64 kHz.

PZT-PMN Ceramics for Large Displacement Piezoelectric Devices

Piezoelectric and dielectric properties as functions of x and y mole ratio in yPb(ZrxTil-x)O(1-y)Pb(Mn1/3/Nb/2/3/)O, ceramics, PZT-PMN, are investigated for large displacement piezoelectric devices. From the experimental results, when y is 0.95 and x is 0.505, the piezoelectric and dielectric properties are maximum, that is, electromechanical coupling coefficient(kp), piezoelectric strain constant(d33/), permittivity(33/T//0/), and Curie temperature are 58 %, 272 pC/N, 1520 and about 350, respectively. Also, when y is 0.90 and x is 0.50, their properties are 56 %, 242 pC/N, 1220, and 290, respectively. As MgO dopant is added from 0 wt% to 1 wt%, kp increases to 63 % and Qm decreases to 500 at the MgO dopant of 0.1 wt%, and then kp decreases to 57 % as MgO is added.

The Design and Characteristics of Disk-Type Ultrasonic Motor Using Complex Vibration Mode

In this paper, disk-type ultrasonic motor using a combination of radial and bending vibration modes is newly designed and fabricated. The characteristics of the test motor are also measured. By means of traveling elastic wave induced at the surface of circumference of the elastic disk, a steel bar in contact with the surface of circumference of elastic disk bonded onto the piezoelectric ceramic disks is driven in both directions by changing the sine and cosine voltage inputs. The stator of the motor is composed of two sheets of piezoelectric ceramic disk to bond onto both surfaces of a elastic disk, respectively. As the results, the diameter of elastic body is increased, the resonant frequency is decreased. The resonant frequency of the stator is about 92 kHz, which is composed with piezoelectric ceramic disks of 28 mm in diameter and 2 mm in thickness, and an elastic body of 32 mm in diameter and 2 mm in thickness. A driving voltage of 20 Vpp produces 200 rpm with a torque of 1 Nm and an efficiency of about 10%.

PD characteristics according to applied voltages and void aspects in LDPE

Flat type voids are made in low density polyethylene, which are different in size and number of voids, for the purpose of investigation of PD characteristics according to applied voltage and void aspects. The PD quantities measured are discharge current and energy, peak PD magnitude and repetition rate. As the experimental results, the discharge mode is changed Townsend to streamer depending on the increasement of applied voltage. The generation of large peak charge may be affected by tangential electrical stress due to charged neighbor sites. This effect is verified by simulation. Increases of repetition rate may be explained by the fact that the discharges generated in each discharging site are amassed.

Dielectric and conduction properties in MOS capacitor irradiated under Co-60 gamma ray

When metal-oxide-semiconductor (MOS) device is exposed to radiation, the resultant effects can cause the modulation and/or degradation in device characteristics and its operating life. In this paper, the irradiation effects on MOS structure were investigated by the measurements of C-V, D-V, and I-V characteristics. From the experimental results, it is confirmed that the peak of dissipation factor is due to the interaction between majority carriers and interface states which induced by radiation. We also found that the measurements of dissipation factor could be very useful method as the evaluation tool of irradiation effects in MOS structure. The I-V characteristics could be explained by traps in the oxide created by radiation, and charges trapped at interface of Si-SiO/sub 2/.<<ETX>>