• Title/Summary/Keyword: 함수센서

Search Result 475, Processing Time 0.031 seconds

Directivity Characteristics of Non-Linear Array for Wide-Band One-Shot Beamforming (광대역 단일빔형성을 위한 비선형배열의 지향 특성)

  • 도경철;손경식
    • The Journal of the Acoustical Society of Korea
    • /
    • v.18 no.3
    • /
    • pp.27-34
    • /
    • 1999
  • This paper proposes an algorithm to design the non-linear array so as to form efficiently the one-shot beam with relatively less sensors for acoustic measurement. In this algorithm, according to the spatial sampling theory the part for high frequency(HF) band has equispaced sensor array and the sensor distances below the HF band are decided as a function of number of HF sensors. As the results of the simulations, the mean and variances of directivity index(DI) of non-linear array which has less sensors are similar to those of linear array. and the DI variation for beam steering angle is very small. And the beam width at -2dB point is 6.8°. Thus it is confirmed that the design algorithm for non-linear array which is proposed to have less sensors can be efficiently used in acoustic measurement.

  • PDF

Development of Adaptive Signal Pattern Recognition Program and Application to Classification of Defects in Weld Zone by AE Method (적응형 신호 형상 인식 프로그램 개발과 AE법에 의한 용접부 결함 분류에 관한 적용 연구)

  • Lee, K.Y.;Lim, J.M.;Kim, J.S.
    • Journal of the Korean Society for Nondestructive Testing
    • /
    • v.16 no.1
    • /
    • pp.34-45
    • /
    • 1996
  • The signal pattern recognition program which can perform signal acquisition and processing, the extraction and selection of features, the classifier design and the evaluation, is developed and applied to the classification of artificial defects in the weld zone of Austenitic STS304. The neural network classifier is compared with the linear discriminant function classifier and the empirical Bayesian classifier. The signal through a broadband sensor is compared with that through a resonance type sensor. In recognition rate, the neural network classifier is best, and the signal through a broadband sensor is better.

  • PDF

A Study on the Fault Tolerant Control System for Aircraft Sensor and Actuator Failures via Neural Networks (신경회로망을 이용한 항공기 센서 및 구동장치 고장보완 제어시스템 설계에 관한 연구)

  • Song, Yong Kyu
    • Journal of Advanced Navigation Technology
    • /
    • v.7 no.2
    • /
    • pp.171-179
    • /
    • 2003
  • In this paper a neural network-based fault tolerant control system for aircraft sensor and actuator failures is considered. By exploiting flight dynamic relations a set of neural networks is constructed to detect sensor failure and give alternative signal for the faulty sensor. For actuator failures another set of neural networks is designed to perform fault detection, identification, and accomodation which returns the aircraft to a new stable trim. Integrated system is simulated to show the performance of the system with sensor and control surface failures.

  • PDF

다공성 나노 Pd 박막의 수소 검출 특성

  • No, Hui-Jun;Park, Jin-Seong;Kim, Hyeon-Jong;Kim, An-Na;Han, Min-A;Lee, Ho-Nyeon
    • Proceedings of the Korean Institute of Surface Engineering Conference
    • /
    • 2018.06a
    • /
    • pp.84.1-84.1
    • /
    • 2018
  • 현재 사용되고 있는 화석 연료는 고갈되고 있으며 지구온난화와 같은 환경오염을 일으키는 주원인으로 이를 대체하는 에너지원으로서 수소가 주목받고 있다. 그러나 수소는 상온 및 대기압에서 4 %의 낮은 LEL (lower explosive limit)을 가지므로 높은 인화성과 폭발성을 가진다. 또한 무색, 무취한 성질을 가지고 있어 사람에 의해 검출되지 않는다. 그러므로 상온에서의 수소 농도를 정량화하고 검출하기 위한 방법이 필요하다. 수소를 검출하기 위한 수소센서에는 저항, 촉매, 광학, 일함수 등을 이용한 센서들이 있으며 그 중 저항을 이용한 귀금속 기반 수소센서가 널리 알려져 있다. 팔라듐(Pd), 백금 (Pt)와 같은 귀금속 기반 수소센서는 높은 수소 용해도 및 확산으로 인해 수소에 우수한 선택성을 가진다. 특히 Pd는 흡착에 대한 친화성이 매우 우수하다. 팔라듐에 수소가 노출되면, 수소가 Pd 격자로 확산되어 Pd-hydride를 형성시켜 부피가 팽창되고 저항이 변한다. 이러한 특성을 바탕으로 팔라듐의 저항 변화를 기반으로 한 수소센서의 개발이 진행되고 있다. 본 연구에서는 물리기상증착 (PVD)을 이용하여 다양한 다공성 나노 Pd 박막을 가지는 수소센서를 제작하였으며, 수소 농도에 따른 실온에서의 수소 검출 특성을 관찰하였다. 제작된 다공성 나노 Pd 박막의 특성은 SEM, TEM 및 XRD를 통하여 확인하였다. 다공성 나노 Pd 박막이 수소에 노출 되었을 때 전자 산란 및 접촉 면적의 증가에 따른 저항의 변화를 확인하였다.

  • PDF

Modeling of Sound-structure Interactions for Designing a Piezoelectric Micro-Cantilever Acoustic Vector Sensor (압전 미세 외팔보 형 수중 음향 벡터센서의 작동 원리와 설계 기법)

  • Yang, Seongkwan;Kim, Junsoo;Moon, Wonkyu
    • The Journal of the Acoustical Society of Korea
    • /
    • v.34 no.2
    • /
    • pp.108-116
    • /
    • 2015
  • An acoustic vector sensor is a device that is capable of measuring the direction of wave propagation and the acoustic pressure. In this paper, the modeling of micro-cantilever sensor for the vector sensor are proposed by consideration of acoustic phenomenon in water. Two models based on unimorph structure are proposed in this paper and corresponding transfer function which describes the relation between input pressure wave and output voltage depending on incidence angle and frequency of pressure wave is derived based on lumped model. It has been shown that very thin and flexible micro-cantilever can be used to measure directly the particle velocity component in water.

Material Recognition Sensor Using Fuzzy Neural Network Inference of Thermal Conductivity (퍼지신경회로망의 열전도도 추론에 의한 재질인식센서의 개발)

  • Lim, Young-Cheol;Park, Jin-Kyu;Ryoo, Young-Jae;Wi, Seog-O;Park, Jin-Soo
    • Journal of Sensor Science and Technology
    • /
    • v.5 no.2
    • /
    • pp.37-46
    • /
    • 1996
  • This paper describes a system that can be used to recognize unknown materials regardless of the change in ambient temperature by using temperature response curve fitting and fuzzy neural network(FNN). There are problems with a recognition system which utilize temperature responses. It requires too many memories to store the vast temperature response data and it has to be filtered to remove the noise which occurs in experiments. Thus, this paper proposes a practical method using curve fitting to remove the above problems of memories and noise. Also, the FNN is proposed to overcome the problem caused by the change of ambient temperature. Using the FNN which is learned by temperature responses on fixed ambient temperatures and known thermal conductivity, the thermal conductivity of the material can be inferred on various ambient temperatures. So the material can be recognized via its thermal conductivity.

  • PDF

Analysis of Saturation and Ground Water Level at Embankment by TDR Sensor (TDR센서를 이용한 제방의 포화도 및 지하수위 해석)

  • Kim, Ki-Young;Han, Heui-Soo;Lee, Jae-Ho;Park, Min-Cheol
    • Journal of the Korean Geotechnical Society
    • /
    • v.27 no.2
    • /
    • pp.63-72
    • /
    • 2011
  • The measured ground water behavior by TDR (time domain reflectometer) sensors were analyzed by the data filtering technique such as moving average method and Fourier transform, and the ground water level and unsaturated zone were tried to be determined numerically. At first, the variation of TDR data according to the saturation degree was measured by lab test, which is translated as a function of saturation degree. Then, changes of ground water level and lateral seepage in field conditions were simulated using acrylic pipe, and the measured data were analyzed to make calibration curve. Furthermore, TDR sensors were installed into the in-situ embankment to insure the field application. The saturation degree, unsaturated and dried zones were determined from the measured data.

Image Deblurring Using Vibration Information From 3-axis Accelerometer (3축 가속도 센서의 흔들림 정보를 이용한 영상의 Deblurring)

  • Park, Sang-Yong;Park, Eun-Soo;Kim, Hak-Il
    • Journal of the Institute of Electronics Engineers of Korea SC
    • /
    • v.45 no.3
    • /
    • pp.1-11
    • /
    • 2008
  • This paper proposes a real-time method using a 3-axis accelerometer to enhance blurred images taken from a camera loaded in mobile devices. Blurring phenomenon is a smoothing effect occurring in photo images. Algorithms to cope with blurring phenomenon is essential since small-size mobile devices tremble severely by even a tiny hand-shaking of a user. In this paper, accurate sensing characteristics of the 3-axis accelerometer is acquired by applying the sensor in pendulum motion and the blurring phenomenon is modeled as a uniform distribution and Gaussian distribution. Also, non-Gaussian distributed model is observed in the experiment of real blurring phenomenon and a particular deblurring function is designed by reversing the model. It has been demonstrated that the application of trembling information to the deblurring function adequately removes the blurring phenomenon.

Robust Particle Filter Based Route Inference for Intelligent Personal Assistants on Smartphones (스마트폰상의 지능형 개인화 서비스를 위한 강인한 파티클 필터 기반의 사용자 경로 예측)

  • Baek, Haejung;Park, Young Tack
    • Journal of KIISE
    • /
    • v.42 no.2
    • /
    • pp.190-202
    • /
    • 2015
  • Much research has been conducted on location-based intelligent personal assistants that can understand a user's intention by learning the user's route model and then inferring the user's destinations and routes using data of GPS and other sensors in a smartphone. The intelligence of the location-based personal assistant is contingent on the accuracy and efficiency of the real-time predictions of the user's intended destinations and routes by processing movement information based on uncertain sensor data. We propose a robust particle filter based on Dynamic Bayesian Network model to infer the user's routes. The proposed robust particle filter includes a particle generator to supplement the incorrect and incomplete sensor information, an efficient switching function and an weight function to reduce the computation complexity as well as a resampler to enhance the accuracy of the particles. The proposed method improves the accuracy and efficiency of determining a user's routes and destinations.

Link Energy Efficiency Routing Strategy for Optimizing Energy Consumption of WBAN (WBAN의 에너지 소비 최적화를 위한 링크 에너지 효율 라우팅 전략)

  • Lee, Jung-jae
    • Journal of Internet Computing and Services
    • /
    • v.23 no.5
    • /
    • pp.1-7
    • /
    • 2022
  • IoT technology that utilizes wireless body area networks (WBAN) and biosensors is an important field in the health industry to minimize resources and monitor patients. In order to integrate IoT and WBAN, a cooperative protocol that constitutes WBAN's limited sensor nodes and rapid routing for efficient data transmission is required. In this paper we propose an we propose an energy efficient and cooperative link energy-efficient routing strategy(LEERS) to solve the problems of redundant data transmission detection and limited network sensor lifetime extention. The proposed scheme considers the hop count node congestion level towards the residual energy sink and bandwidth and parameters. In addition, by determining the path cost function and providing effective multi-hop routing, it is shown that the existing method is improved in terms of residual energy and throughput