• The Journal of Korea Robotics Society
• /
• v.5 no.2
• /
• pp.110-119
• /
• 2010

This paper aims to add the autonomous driving capability to the inverted pendulum system which maintains the inverted pendulum upright stably. For the autonomous driving from the starting position to the goal position, the motion control algorithm is proposed based on the dynamics of the inverted pendulum robot. To derive the dynamic model of the inverted pendulum robot, a three dimensional robot coordinate is defined and the velocity jacobian is newly derived. With the analysis of the wheel rolling motion, the dynamics of inverted pendulum robot are derived and used for the motion control algorithm. To maintain the balance of the inverted pendulum, the autonomous driving strategy is derived step by step considering the acceleration, constant velocity and deceleration states simultaneously. The driving experiments of inverted pendulum robot are performed while maintaining the balance of the inverted pendulum. For reading the positions of the inverted pendulum and wheels, only the encoders are utilized to make the system cheap and reliable. Even though the derived dynamics works for the slanted surface, the experiments are carried out in the standardized flat ground using the inverted pendulum robot in this paper. The experimental data for the wheel rolling and inverted pendulum motions are demonstrated for the straight line motion from a start position to the goal position.

• Journal of the Institute of Electronics Engineers of Korea SC
• /
• v.37 no.3
• /
• pp.72-83
• /
• 2000

This paper presents the implementation of the position control system for 3 phase induction motor using reaching mode controller and neural networks. The reaching mode controller is used to bring the position error and speed error trajectories toward the sliding surface and to train neural networks at the first time. The structure of the reaching mode controller consists of the switch function of sliding surface. And feedforward neural networks approximates the equivalent control input using the reference speed and reference position and actual speed and actual position measured form an encoder and, are tuned on-line. The reaching mode controller and neural networks are applied to the position control system for 3 phase induction motor and, are compared with a PI controller through computer simulation and experiment respectively. The results are illustrated that the output of reaching mode controller is decreased and feedforward neural networks take charge of the main part for the control action, and the proposed controllers show better performance than the PI controller in abrupt load variation and the precise control is possible because the steady state error can be minimized by training neural networks.

• Korean Journal of Remote Sensing
• /
• v.38 no.5_2
• /
• pp.707-723
• /
• 2022

Although satellite-based sea surface temperature (SST) is advantageous for monitoring large areas, spatiotemporal data gaps frequently occur due to various environmental or mechanical causes. Thus, it is crucial to fill in the gaps to maximize its usability. In this study, daily SST composite fields with a resolution of 4 km were produced through a two-step machine learning approach using polar-orbiting and geostationary satellite SST data. The first step was SST reconstruction based on Data Interpolate Convolutional AutoEncoder (DINCAE) using multi-satellite-derived SST data. The second step improved the reconstructed SST targeting in situ measurements based on light gradient boosting machine (LGBM) to finally produce daily SST composite fields. The DINCAE model was validated using random masks for 50 days, whereas the LGBM model was evaluated using leave-one-year-out cross-validation (LOYOCV). The SST reconstruction accuracy was high, resulting in R² of 0.98, and a root-mean-square-error (RMSE) of 0.97℃. The accuracy increase by the second step was also high when compared to in situ measurements, resulting in an RMSE decrease of 0.21-0.29℃ and an MAE decrease of 0.17-0.24℃. The SST composite fields generated using all in situ data in this study were comparable with the existing data assimilated SST composite fields. In addition, the LGBM model in the second step greatly reduced the overfitting, which was reported as a limitation in the previous study that used random forest. The spatial distribution of the corrected SST was similar to those of existing high resolution SST composite fields, revealing that spatial details of oceanic phenomena such as fronts, eddies and SST gradients were well simulated. This research demonstrated the potential to produce high resolution seamless SST composite fields using multi-satellite data and artificial intelligence.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.26 no.6
• /
• pp.834-841
• /
• 2022

Recently, applying artificial intelligence technologies in various fields of production has drawn an upsurge of research interest due to the increase for smart factory and artificial intelligence technologies. A great deal of effort is being made to introduce artificial intelligence algorithms into the defect detection task. Particularly, detection of defects on the surface of metal has a higher level of research interest compared to other materials (wood, plastics, fibers, etc.). In this paper, we compare and analyze the speed and performance of defect classification by combining machine learning techniques (Support Vector Machine, Softmax Regression, Decision Tree) with dimensionality reduction algorithms (Principal Component Analysis, AutoEncoders) and two convolutional neural networks (proposed method, ResNet). To validate and compare the performance and speed of the algorithms, we have adopted two datasets ((i) public dataset, (ii) actual dataset), and on the basis of the results, the most efficient algorithm is determined.

• Journal of the Korean Society for Precision Engineering
• /
• v.19 no.8
• /
• pp.180-186
• /
• 2002

Hot Plate is the major unit that it used to remove damp of wafer surface, to strength adhesion of photoresist (PR) and to bake coated PR in FAB process of semiconductor. The badness of Hot Plate (HP) has directly influence upon the performance of wafer, it is necessary to guarantee the performance of HP. In this study, a reliability evaluation system has been designed and developed, which is to measure and to estimate thermal uniformity and flatness of HP in range of temperature 0~$250^\circC$. This system has included the techniques which measures and analyzes thermal uniformity using infrared thermal vision, and which compensates measuring error of flatness using laser displacement sensor For measuring flatness, a measurement stage of 3 axes are developed which adapts the precision encoder. The allowable error of this system in respect of thermal uniformity is less $than\pm0.1^\circC$ and in respect of flatness is less $than\pm$1mm . It is expected that the developed system can measure from $\Phi200mm\;(wafer 8＂)\;to\;\Phi300mm$ (wafer 12＂) and also can be used in performance test of the Cool Plate and industrial heater, etc.

• International Journal of Precision Engineering and Manufacturing
• /
• v.8 no.2
• /
• pp.26-31
• /
• 2007

A novel scanning probe measurement system was developed to enable precise profile measurements of microaspheric surfaces. An air-bearing stylus with a microprobe was used to perform the surface profile scanning. The new system worked in a contact mode and had the capability of measuring micro-aspheric surfaces with large tilt angles and complex profiles. Due to limitations resulting from the contact mode, such as possible damage caused by the contact force and lateral resolution restrictions from the curvature of the probe tip, several system improvements were implemented. An air bearing was used to suspend the shaft of the probe to reduce the contact force, enabling fine adjustments of the contact force by changing the air pressure. The movement of the shaft was measured by a linear encoder with a scale attached to the actual shaft to avoid Abbe errors. A $50-{\mu}m-diameter$ glass sphere was bonded to the tip of the probe to improve the lateral resolution of the system. The maximum contact force of the probe was 10 mN. The shaft was capable of holding the probe continuously if the contact force was less than 40 mN, and the resolution of the probe could be as high as 10 nm, The performance of the new scanning probe measurement system was verified by experimental data.

• Journal of the Korean Geotechnical Society
• /
• v.34 no.10
• /
• pp.29-38
• /
• 2018

The slime formed at the bottom of the borehole causes the excessive displacement and loss of the bearing capacity of the drilled shaft. In this study, the slime meter is developed for the evaluation of the slime based on the electrical properties of the fluid and the slime in the borehole. The slime meter is composed of a probe instrumented with electrodes and temperature sensor and a frame with rotary encoder, so that the slime meter profiles the electrical resistivity compensated with temperature effect along the depth. For the application of the slime meter, three field tests are conducted at a borehole with a diameter of 3 m and a depth of 46.9 m with different testing time and locations. For all the tests, the experimental results show that while electrical resistivities are constantly measured in the fluid, the electrical resistivities sharply increase at the surface of the slime. Therefore, the slime thicknesses are estimated by the differences in the depths of the slime surface and the ground excavation. The experimental results obtained at the same testing point with different testing time show that the estimated thickness of the slime increases by the elapsed time. Also, the estimated slime at the side of the borehole is thicker than that at the center of the borehole. As the slime meter estimates the slime in the borehole by measuring the electrical resistivity with simple equipment, the slime meter may be effectively used for the evaluation of the slime formed at the bottom of the borehole.

• Restorative Dentistry and Endodontics
• /
• v.33 no.2
• /
• pp.141-147
• /
• 2008

This study was aimed to develop an instrument for real-time measurement of fluid conductance and to investigate the hydrodynamics of dentinal fluid. The instrument consisted of three parts; (1) a glass capillary and a photo sensor for detection of fluid movement, (2) a servo-motor, a lead screw and a ball nut for tracking of fluid movement, (3) a rotary encoder and software for data processing. To observe the blocking effect of dentinal fluid movement, oxalate gel and self-etch adhesive agent were used. BisBlock (Bisco) and Clearfil SE Bond (Kuraray) were applied to the occlusal dentin surface of extracted human teeth. Using this new device, the fluid movement was measured and compared between before and after each agent was applied. The instrument was able to measure dentinal fluid movement with a high resolution (0.196 nL) and the flow occurred with a rate of 0.84 to 15.2 nL/s before treatment. After BisBlock or Clearfil SE Bond was used, the fluid movement was decreased by 39.8 to 89.6%.