• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.672-676
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• 2004

In this paper, measuring system of 5 DOF motion errors are proposed using two capacitive type sensor, a straight edge and a laser interfoerometer. Yawing error and pitching error are measured using the laser interferometer, and rolling error is measured by the reversal method using a capacitive type sensor. Linear motion errors of horizontal and vertical direction are measured using the sequential two point method. In this case, influence of angular motion errors is compensated using the previously measured angular motion errors. In the horizontal direction, measuring accuracy is within 0.05 $\mu$m and 0.27 arcsec, and in the vertical direction, it is within 0.15 $\mu$m and 0.5 arcsec. From these results, it is confirmed that the proposed measureing system is very effective to the measurement of 5 DOF motion errors in the ultra precision feed tables.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.1018-1021
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• 2003

A scratch tester was developed to evaluate the adhesive strength at interface between thin film and substrate(silicon wafer). Under force control, the scratch tester can measure the normal and the horizontal forces simultaneously as the probe tip of the equipment approaches to the interface between thin film and substrate of wafer. The capacity of each component of force sensor is 0.1 N ∼ 100 N. In addition, the tester can detect the signal of elastic wave from AE sensor(frequency range of 900 kHz) attached to the probe tip and evaluate the bonding strength of interface. Using the developed scratch tester. the feasibility test was performed to evaluate the adhesive strength of semiconductor wafer.

• Journal of Institute of Control, Robotics and Systems
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• v.13 no.7
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• pp.656-663
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• 2007

A new dynamic balancing algorithm has been proposed to minimize the number of sensors necessary for the horizontal balancing of the mobile inverted pendulum while maintaining the same level of the commercial performance. The inverted pendulum technique is getting attention and there have been many researches on the Segway since the US inventor Dean Kamen commercialized. One of the major problems of the Segway is that many sensors are required for the control of the Segway, which results in the high price. In this research, a single gyro and a tilt sensor are fused to obtain the absolute tilt information, which is applied for the control of the mobile inverted pendulum. A dynamic balancing technique has been developed and applied for a robust control system against disturbances. The intelligent handling and stable curving of the Segway as a next generation mobile tool are verified with a human loading.

• Journal of Korean Association for Spatial Structures
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• v.18 no.2
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• pp.51-58
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• 2018

Recently, measuring instruments for SHM of structures had being developed. In general, the wireless transmission of sensor signals, compared to its wired counterpart, is preferable due to its absence of triboelectric noise and elimination of the requirement for cumbersome cable. However, the research on the tall buildings with relatively small vibration levels is insufficient. Therefore, in this paper, we used the wireless MEMS sensor and iPad to compare and analyze the vibration measurements of three tall buildings and two towers.

• Journal of Korean Association for Spatial Structures
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• v.17 no.3
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• pp.57-64
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• 2017

Recently, measuring instruments for SHM of structures had being developed. In general, the wireless transmission of sensor signals, compared to its wired counterpart, is preferable due to its absence of triboelectric noise and elimination of the requirement for cumbersome cable. Preliminary studies on the continuous vibration measurement of high-rise buildings using MEMS sensors have been carried out. However, the research on the low-rise buildings with relatively small vibration levels is insufficient. Therefore, in this paper, we used the wireless MEMS sensor to compare and analyze the vibration measurements of three low-rise buildings.

• Journal of Astronomy and Space Sciences
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• v.20 no.4
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• pp.359-364
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• 2003

In this paper, we present multi-sensor data fusion for telematics application. Successful telematics can be realized through the integration of navigation and spatial information. The well-determined acquisition of vehicle's position plays a vital role in application service. The development of GPS is used to provide the navigation data, but the performance is limited in areas where poor satellite visibility environment exists. Hence, multi-sensor fusion including IMU (Inertial Measurement Unit), GPS(Global Positioning System), and DMI (Distance Measurement Indicator) is required to provide the vehicle's position to service provider and driver behind the wheel. The multi-sensor fusion is implemented via algorithm based on Kalman filtering technique. Navigation accuracy can be enhanced using this filtering approach. For the verification of fusion approach, land vehicle test was performed and the results were discussed. Results showed that the horizontal position errors were suppressed around 1 meter level accuracy under simulated non-GPS availability environment. Under normal GPS environment, the horizontal position errors were under 40㎝ in curve trajectory and 27㎝ in linear trajectory, which are definitely depending on vehicular dynamics.

• Journal of Institute of Control, Robotics and Systems
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• v.19 no.4
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• pp.372-378
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• 2013

In this paper, we research the localization problem of the crawler-type inspection robot for underwater structure which travels an outer wall of underwater structure. Since various factors of the underwater environment affect an encoder odometer, it is hard to localize robot itself using only on-board sensors. So in this research we used a depth sensor and an IMU to compensate odometer which has extreme error in the underwater environment through using Extended Kalman Filter(EKF) which is normally used in mobile robotics. To acquire valid measurements, we implemented precision sensor modeling after assuming specific situation that robot travels underwater structure. The depth sensor acquires a vertical position of robot and compensates one of the robot pose, and IMU is used to compensate a bearing. But horizontal position of robot can't be compensated by using only on-board sensors. So we proposed a localization algorithm which makes horizontal direction error bounded by using kinematics relationship. Also we implemented computer simulations and experiments in underwater environment to verify the algorithm performance.

• Proceedings of the IEEK Conference
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• 2003.11b
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• pp.199-202
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• 2003

In the research for Unmaned Air Vehicles(UAVs), the use of Vision-sensor has been increased. It is possible to calculate the position information of air vehicle by finding a horizontal line. In this paper, we proposed a vision-based algorithm for finding the horizontal line. Experimental results show that the proposed algorithm is faster than an existing algorithm.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.05a
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• pp.655-662
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• 2007

This paper presents a disk-type capacitive sensor for simultaneous measurement of five-dimensional motions of a target. The sensor can be manufactured with a printed circuit board (PCB) such that the sensor can be integrated with its electronics in a single PCB board, whereby the manufacturing costs is considerably reduced. The sensor is optimally designed through an error analysis of possible mechanical errors. Furthermore, the sensor can correct the horizontal motion measurement errors due to the sensor installation tilting error. A proto-type PCB sensor, electronics and a test rig were built, and the effectiveness of the developed sensor was proved through experiments.

• Proceedings of the KWS Conference
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• 1997.05a
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• pp.129-132
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• 1997