• The Magazine of the IEIE
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• v.38 no.1
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• pp.50-55
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• 2011

초음파 시스템은 진단 영상뿐만 아니라 초음파 수술과 같이 초음파를 사용하여 특정 세포를 제거하거나, 또는 일반적인 수술을 위한 가이드 영상을 제공하는 등 그 활용이 증가되고 있다. 반면, 기존 초음파 시스템은 크기가 커서 클리닉 센터나 종합병원 등에서 이동성 및 공간 효율성이 낮고 환자에 관한 주치의들의 진단 활동 반경이 매우 제한적이라는 불편함을 초래한다. 본 논문은 서버 클라이언트 기반의 무선 초음파 진단 시스템에서 프루브가 수신한 초음파 반사 신호를 무선으로 실시간 전송하기 위해서 압축센싱과 산술 부호의 연접을 통한 손실 압축 알고리즘을 제안한다.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2011.04a
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• pp.40-43
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• 2011

최근, 레이저 초음파 영상화 기법은 구조물의 비접촉식 손상 진단을 위해 널리 연구되고 있다. 초음파 영상화 기법의 가장 큰 장점은 비접촉식으로 구조물의 손상을 진단할 수 있고, 가진 및 측정 지점을 자유로이 이동할 수 있다는 점이다. 따라서 이는 고온이나 동적상태의 구조물에 적용이 가능하며, 시간과 공간상의 충분한 데이터를 획득할 수 있으므로 역문제 (Inverse problem)를 해결할 필요 없이 완전한 초음파의 전파 형상을 얻을 수 있다. 지난 연구들에서는 충분한 가진력 혹은 측정 민감도를 확보하기 위해 가진 레이저와 부착형 센서의 조합이나 부착형 가진 트렌스듀서와 센싱 레이저의 조합으로 초음파 영상을 획득하고자 하였다. 하지만 이들 조합은 가진 혹은 측정 지점이 구조물에 부착되어 있어 완전한 비접촉식 기법을 구현하지 못하였다. 이를 극복하고자 레이저와 EMAT 센서 등의 조합이 시도되어 왔으나, 이 또한 EMAT 센서의 적용 거리에 따른 한계점을 지니고 있다. 본 연구에서는 가진 레이저 (Nd:Yag)의 스캐닝을 통해 다양한 가진 점에서 발생된 초음파가 탄성체 구조물을 통해 전파되고, 이를 센싱 레이저 (Laser Doppler Vibrometer)를 이용하여 측정함으로써 비접촉식 초음파 영상화를 구현하였다. 나아가, 정상파 필터(Standing-wave filter)를 이용하여 구현된 초음파 영상으로부터 손상 영향만 검출해 내는 기법을 개발했다. 개발된 기법은 복합재 시편의 층간박리 (Delamination) 진단을 통해 검증하였다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.10a
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• pp.285-288
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• 2007

A realization for automatic stock cubic measuring and distributing management embedded system with 3 dimensional ultrasonic sensing is presented in this paper. The height and width of cubic are measured by comparing the 3 values from 3 ultrasonic sensors with reference when an object is passing the conveyer and length is calculated by the passing time and velocity, compensate cubic values for error to vary with the environment temperature, and reduce the error by averaging the sensing data not to be right posture of object. The system enables to classify and load a packed stocks at the store and transportation practically based on the rectangular hexahedral objects.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.6
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• pp.167-173
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• 2016

Compressed Sensing(CS) is the theory that can recover signals which are sampled below the Nyquist sampling rate to original analog signals. In this paper, we propose the estimation algorithm of ultrasonic attenuation coefficients in the frequency domain using CS. While most estimation algorithms transform the time-domain signals into the frequency-domain using the Fourier transform, the proposed method directly utilize the spectral information in the recovery process by the basis matrix without the completely recovered signals in the time domain. We apply three transform bases for sparsifying and estimate the attenuation coefficients using the Centroid Downshift method with Dual-reference diffraction compensation technique. The estimation accuracy and execution time are compared for each basis matrix. Computer simulation results show that the DCT basis matrix exhibits less than 0.35% estimation error for the compressive ratio of 50% and about 6% average error for the compressive ratio of 70%. The proposed method which directly extracts frequency information from the CS signals can be extended to estimating for other ultrasonic parameters in the Quantitative Ultrasound (QUS) Analysis.

• Land and Housing Review
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• v.2 no.4
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• pp.407-413
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• 2011

This paper reports a novel structural health monitoring (SHM) technique for detecting de-bonding between a concrete beam and CFRP (Carbon Fiber Reinforced Polymer) sheet that is attached to the concrete surface. To achieve this, a multi-scale actuated sensing system with a self-sensing circuit using piezoelectric active sensors is applied to the CFRP laminated concrete beam structure. In this self-sensing based multi-scale actuated sensing, one scale provides a wide frequency-band structural response from the self-sensed impedance measurements and the other scale provides a specific frequency-induced structural wavelet response from the self-sensed guided wave measurement. To quantify the de-bonding levels, the supervised learning-based statistical pattern recognition was implemented by composing a two-dimensional (2D) plane using the damage indices extracted from the impedance and guided wave features.

• Bulletin of the Society of Naval Architects of Korea
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• v.57 no.3
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• pp.24-27
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• 2020

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2004.05b
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• pp.269-272
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• 2004

The respiration measurement method using the ultrasound sensor hardly gets an influence of an error of inertia and pressure and it is a respiratory detection device available semi-permanently. This device measures the amount and flow of respiration through using a delivery speed difference of the ultrasound waves that are a return format by the pneumatic stream that is a flogging of ultrasound waves during transmission and receipt as having used a characteristic of ultrasound waves. In this paper, it improved sensitivity of a signal to happen during transmission and receipt of a sensor because measurement must be performed with a patient to the center and measurement was played in a weak breathing so that it was possible.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.2
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• pp.509-515
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• 2004

Pulmonary function tests are widely used to diagnose and determine patients' therapy in clinic. And it was also applied in the research of the physiology and dynamics for lung disease. Among the pulmonary function tests, spirometry is the most easy and economic test. Spirometers are medical instruments that measure the instantaneous rate of volume flow of respired Bas. The mechanical spirometer was mostly used in the past. Up to the present, the most popular method of spirometer is the differential pressure technique with which change in the volume of flow are transferred to change in pressure. This kind of instrument suffers from several limitations, pressure drop, difficulty in maintenance and short period of calibration. Therefore, this study has begun to implement ultrasound spirometer, which is free of pressure loss and has wide range, focusing on the flow measurement technique and diagnostic algorithm.

• Journal of the Korean Institute of Intelligent Systems
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• v.17 no.4
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• pp.506-510
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• 2007

Digital Magnetic Compass(DMC) has a robust feature against interference in the indoor environment better than compass which is easily disturbed by electromagnetic sources or large ferromagnetic structures. Ultrasonic Sensors are cheap and can give relatively accurate range readings. So they ate used in Simultaneous Localization and Mapping(SLAM). In this paper, we study the Simultaneous Localization and Mapping(SLAM) of mobile robot in the indoor environment with Digital Magnetic Compass and Ultrasonic Sensors. Autonomous mobile robot is aware of robot's moving direction and position by the restricted data. Also robot must localize as quickly as possible. And in the moving of the mobile robot, the mobile robot must acquire a map of its environment. As application for the Simultaneous Localization and Mapping(SLAM) on the autonomous mobile robot system, robot can find the localization and the mapping and can solve the Kid Napping situation for itself. Especially, in the Kid Napping situation, autonomous mobile robot use Ultrasonic sensors and Digital Magnetic Compass(DMC)'s data for moving. The robot is aware of accurate location By using Digital Magnetic Compass(DMC).

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1789-1790
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• 2008

본 연구는 오류를 최소화한 초음파 수신량에 따라 구동부의 이동위치를 결정하고 이에 따른 각각의 제어신호를 출력하여 원단, 제지 등의 끝단을 정밀하게 제어함으로써 헌팅현상 등을 방지하여 물체가 더 정확한 위치에서 감기도록 유도하는 장치에 관한 것이다.