• Journal of KSNVE
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• v.9 no.3
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• pp.565-569
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• 1999

Recently, fiber optic hydrophone is a subject which has attracted as a underwater acoustic sensor. In this study, Finite element modeling of fiber optic hydrophone for hollow cylindrical mandrel was performed and the acoustic sensitivity was calculated to estimate the performance of single element fiber optic hydrophone. And acoustic sensitivity was measured in acoustic water tank to verify the result of simulation. The result of FE analysis and experiment is -126 dB re rad/$\mu$ Pa and -128 dB re rad/$\mu$ Pa respectively.

• Journal of the Korean Society for Nondestructive Testing
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• v.25 no.6
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• pp.459-466
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• 2005

The scanning laser source (SLS) technique has been proposed recently as an effective way to investigate small surface-breaking defects, By monitoring the amplitude and frequency changes of the ultrasound generated as the SLS scans over a defect, the SLS technique has provided enhanced signal-to-noise performance compared to the traditional pitch-catch or pulse-echo ultrasonic methods, An extension of the SLS approach to map defects in microdevices is proposed by bringing both the generator and the receiver to the near-field scattering region of the defects, To facilitate near-field ultrasound measurement, silicon microcantilever probes are fabricated using microfabrication technique and their acoustical characteristics are investigated, Then, both the laser-generated ultrasonic source and the microcantilever probe are used to monitor near-field scattering by a surface-breaking defect.

• Journal of KSNVE
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• v.22 no.4
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• pp.28-32
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• 2012

Condition-based maintenance on wind turbines not only involves maintenance, but also encompasses servicing, inspection, measurement and evaluation of the condition of the unit. The current condition can be evaluated on the basis of machine-specific overall vibration values. Until now, overall vibration values had not been defined for wind turbines. In fact, ISO 10816-3 explicitly excludes wind power plants. The new VDI 3834 closes this gap shown in Sheet 1: Vibration values for wind turbines up to 3 MW. In addition to the new VDI 3834 is the ISO 10816-21 in preparation. The author of the article Dr. Edwin Becker is the nominated expert for Germany.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1997.03a
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• pp.207-212
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• 1997

In estimating the formability of sheet metal, the stereo vision system contributes the accuracy of strain of sheet metal, the convenience in measuring the strain of sheet metal, and the handiness in preparing the forming limit diagram by calculating the 3D values and strain of sheet metal. The algorithm has been developed so that the 3D-coordinate values of sheet metal could be calculated by image processing which is composed of camera calibration, and the stereo matching of images in two viewpoints. By comparing with experiments, the possibility and the convenience of algorithm has been verified, which could calculate the 3D-coordinate values of sheet metal automatically by using the preprocessing of the original image of sheet metal, which had the noise before adjusting the camera calibration and the stereo matching algorithm.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1999.08a
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• pp.201-207
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• 1999

The automatic pinhole detection system is described. The goal of this project is to study the feasibility test of the new concept for hole detection. The developed method is able to detect almost 50$\mu\textrm{m}$ pinhole by evaluating the shining of the light as if there is pinhole in the strip. Moreover, it is possible to inspect up to the 200$\mu\textrm{m}$ inclined pinhole. The system cosists of three main functional parts: the source part of the light which is using the linear halogen lamp, the image gathering part which is using a line CCD and the image processing part. The light spot can be controlled and optimized corresponding to the situation of the strip. To eliminate back ground noise, the binary image processing method is adopted.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.28 no.4
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• pp.412-417
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• 1992

In full-speed cruising, the airborne sound pressure levels are measured from 11 small fishing boats operated around Cheju Island. In these measurement, 9 measuring positions are selected in each fishing boats. The results of measurements and analyses are as follows: 1. The sound pressure levels in FRP boats are higher than those in wooden boats. 2. The highest sound pressure level is 112dB(A) at the engine room in C boat, while the lowest one is 72dB(A) at the front deck in K boat. 3. The highest sound pressure level is shown to be in the frequency band less than 500Hz. 4. The highest sound pressure level is shown to be in the frequency band less than 500Hz. 5. Through all 9 positions, the sound pressure levels are higher in B and C boat and lower in E and K boats.

• Journal of Institute of Control, Robotics and Systems
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• v.17 no.12
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• pp.1183-1187
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• 2011

In this paper, an optimal FIR (Finite-Impulse-Response) filter is proposed for discrete time-varying state-space models. The proposed filter estimates the current state using measured output samples on the recent time horizon so that the variance of the estimation error is minimized. It is designed to be linear, unbiased, with an FIR structure, and is independent of any state information. Due to its FIR structure, the proposed filter is believed to be robust for modeling uncertainty or numerical errors than other IIR filters, such as the Kalman filter. For a general system with system and measurement noise, the proposed filter is derived without any artificial assumptions such as the nonsingular assumption of the system matrix A and any infinite covariance of the initial state. A numerical example show that the proposed FIR filter has better performance than the Kalman filter based on the IIR (Infinite- Impulse-Response) structure when modeling uncertainties exist.

• Journal of Institute of Control, Robotics and Systems
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• v.16 no.10
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• pp.991-996
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• 2010

In this paper, a new indoor positioning system based on incident angle measurement of infrared sensor has been suggested. Though there have been various researches on indoor positioning systems using vision sensor or ultrasonic sensor, they have not only advantages, but also disadvantages. In a new positioning system, there are three infrared emitters on fixed known positions. An incident angle sensor measures the angle differences between each two emitters. Mathematical problems to determine the position with angle differences and position information of emitters has been solved. Simulations and experiments have been implemented to show the performance of this new positioning system. The results of simulation were good. Since there existed problems of noise and signal conditioning, the experimented has been implemented in limited area. But the results were acceptable. This new positioning method can be applied to any indoor systems that need absolute position information.

• Journal of Institute of Control, Robotics and Systems
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• v.14 no.9
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• pp.898-903
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• 2008

In most cases, the trajectory of a ballistic missile is well explained by the Kepler's laws. It implies that the remaining trajectory of the ballistic missile including its final destination can be easily predicted if the position and velocity vector of the ballistic missile at any point on its path can be exactly known. Hence, an effective tracking algorithm based on an exact radar measurement model is very important for developing Ballistic Missile Defense(BMD) system. In this paper, we address to design a nonlinear filter, Unscented Kalman Filter(UKF), to track the ballistic missile.

• Proceedings of the IEEK Conference
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• 2000.06e
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• pp.113-116
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• 2000

In this paper presents the portable wireless ECG data detection and diagnosis system based on discreet wavelet transform. An algorithm based on wavelet transform suitable for real time implementation has been developed in order to detect ECG characteristics. In particular, QRS complex, S and T waves may be distinguished form noise, baseline drift or artifacts. Proposed telemetry system that a transmitting media using radio frequency(RF) for the middle range measurement of the physiological signals and receiving media using optical for electromagnetic interference problem. A standard hi-directional serial communication interface between the telemetry system and a personal computer or laptop, allows read-time controlling, diagnosing and monitoring of system. A portable telemetry system within a size. of 65${\times}$125${\times}$45mm consists of three parts: a digital signal processing part for physiological signal detect or diagnose, RF transmitter for data transfer and a optical receiver for command receive. Advantages of proposed telemetry system is wireless middle range(50m) FM transmission, reduce electromagnetic interference to a minimum. which enables a comfortable diagnosis system at home.