• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2000.11a
• /
• pp.713-716
• /
• 2000

In this study, we present a mobile robot for ultrasonic scanning of weldment. magnetic Caterpillar mechanism is selected in order to travel on the inclined surface and vertical wall. A motion control board and motor driver are developed to control four DC-servo motors. A virtual device driver is also developed for the purpose of communicating between the control board and a host PC with Dual 'port ram. To provide the mobile robot with stable and accurate movement, PID control algorithm is applied to the mobile robot control. And a vision system for detecting the weld-line are developed with laser slit beam as a light source. In the experiments, movement of the mobile robot is tested inclined on a surface and a vertical wall.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.8 no.3
• /
• pp.285-291
• /
• 2003

Switched reluctance machine has much attention as a traction drive because of high efficiency, high power and DC series torque characteristics. But the motor has to have a regenerative mode when it is adopted in electric vehicle and current divergence during the regeneration makes difficulties in the control. This paper proposes a reference current limitation strategy for a stable regeneration based on simulations and experimented tests. The motor is operated with conventional current limit and switching angle control method in motoring mode. Simulations and experiments are excuted to verify the feasibility of the proposed method.

• Proceedings of the KIPE Conference
• /
• 1999.07a
• /
• pp.427-430
• /
• 1999

This paper presents a S-FES(Superconducting magnetic bearing Flywheel Energy Storage System) for the purpose of replacing battery used to store the energy. Especially, the design elements of FES, such as the bearing, wheel material, and power converter, etc., is described. The design and manufacturing techniques of the controllable power converter are proposed to generate the sinusoidal output current in the high speed operation and to get the constant DC voltage in the regeneration mode. The cylindrical permanent magnet synchronous motor with halbach array of Nd-Fe-B permanent magnet which is the high coercivity material is used as the driver of FES. The proposed S-FES system shows the stable rotation characteristics at high speed range about 10,000 rpm. To verify the validity of proposed system, the comparative study with the conventional ball bearing system is proceeded and it is well confirmed with the result of the lower friction loss of S-FES system.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2006.08a
• /
• pp.641-643
• /
• 2006

Add-Vision has developed a low-cost print technology for P-OLED displays on flexible substrates that meets several essentials for a new technology including: (1) Functionality including low DC voltage and wide color gamut; (2) Utilization of inexpensive tools; (3) Performance matching entry applications and markets. AVI's process is based on large-area printing of a combination of doped emissive and air-stable cathode inks utilizing truly low-cost tools to create printed P-OLEDs.

• The Transactions of the Korean Institute of Electrical Engineers A
• /
• v.48 no.10
• /
• pp.1215-1221
• /
• 1999

A high speed digital distance relaying algorithm based on a Wavelet Transformation is proposed. To obtain stable phasor values very quickly, first, a lowpass filter which has low cutoff frequency is used. Secondly, db2(Daubechies 2) Wavelet which has the data window of 4 samples is used. A FIR filter which removes the DC-offset component in current relaying signals is applied. In accordance with a series of tests, the operation time of the relaying algorithm is less than 3/4 cycles after faults in a 80 [km], 154[kV], 60[Hz] over-head transmission line system.

• Proceedings of the KIEE Conference
• /
• 2001.07c
• /
• pp.1402-1404
• /
• 2001

Josephson junction arrays of the type $Nb/Al-Al_2O_3/Nb$ were prepared by DC magnetron sputtering. The tunnel barrier was formed by in-situ thermal oxidation. Individual junctions were defined using selective niobium etching process(SNEP). The characteristic curves of Josephson junction arrays fabricated with and without cooling the substrate were represented. The junctions deposited without cooling showed poor characteristics(high leakage current, low gap voltage), and a high quality Josephson junction array of 2,000 junctions with high hysteresis was obtained with cooling and when operated at 74.6 GHz, it generated stable quantized voltage steps up to 2.2 V.

• Proceedings of the KIEE Conference
• /
• 1999.07b
• /
• pp.853-855
• /
• 1999

The induction machine has been used frequently for the system that needs static speed because of its simplicity, durability, credibility and efficiency. But it is nonlinear system for its multi-variable interference. Its controller is more complicated than DC machine's one. So vector control method is needed for its high Performance control. This paper shows that vector control algorithm could be more fast and stable by using Genetic algorithm (GA) based upon Darwin's evolution theory and Mendel's genetics. Methods proposed in here are used to design induction machine's vector controller and to use GA for optimizing the controller's parameter. SIMULINK of MATLAB is used for analysis and conviction of control property

• 제어로봇시스템학회:학술대회논문집
• /
• 2002.10a
• /
• pp.105.6-105
• /
• 2002

Contents 1We developed a new type of lower part of the human-sized BWR (biped walking robot) driven by a new actuator based on the ball screw which has high strength and high gear ratio. Each leg of the robot is composed of three pitch Joints and one roll joint. In all, a 8 degree-of-freedom robot was developed. A new type of actuator for the robot is proposed, which is composed of four bar link mechanism driven by the ball screw. The BWR was designed to walk autonomously by adapting small DC motors for the robot actuators and has an embeded controller system including host computer, batteries and motor drivers. In the performance test, we had basic stable walking data so far, but we f...

• Proceedings of the Korean Society of Machine Tool Engineers Conference
• /
• 2003.10a
• /
• pp.36-40
• /
• 2003

In order to discuss the availability of aerostatic guideways driven by the coreless linear motor to ultra precision machine tools, a prototype of guideway is designed and tested in this research. A coreless linear DC motor with the continuous force of 156N and a laser scale with the resolution of $0.01\mu\textrm{m}$ are used as the feeding system. The experiments are performed on the static stiffness, motion accuracy, positioning accuracy, microstep response and variation of velocity. The guideway also has $0.21\mu\textrm{m}$ of positioning error and $0.09\mu\textrm{m}$ of repeatability, and it shows the stable response against the $0.01\mu\textrm{m}$ resolution step command. The velocity variation of feeding system is less than 0.6%. From these results, it is confirmed that the aerostatic guideway driven by the coreless linear motion is very useful for the ultra precision machine tools.

• 한국가시화정보학회:학술대회논문집
• /
• 2003.11a
• /
• pp.75-78
• /
• 2003

An interfacial instability has recently been observed for the DC- and AC-powered electroosmotic flows of the two miscible electrolyte layers having different concentrations in microchannels. It is rather contrary to our common belief that the flow inside a microchannel is generally stable due to the dominant role of the viscous damping. In this work, we visualized the electroosmotic flow inside a T-channel to validate the numerical predictions. It is clearly shown that the strong vortices (which characterize the interface shapes) are generated at the interface of the two fluids, as was predicted in the numerical analysis.