• The Journal of the Acoustical Society of Korea
• /
• v.36 no.2
• /
• pp.100-107
• /
• 2017

The focused MVDR (Minimum Variance Distortionless Response) can be applied for source localization in near field. However, if the number of sensors are increased, it requires a large amount of calculation to obtain the inverse of the covariance matrix. In this paper we propose a focused MVDR method using that beam space is formed from output of far field beamformer at the subarray. The performances of the proposed method was evaluated by simulation. As a result of simulation, the proposed method has the higher spatial resolution performance then the conventional delay-and-sum beamformer.

• Proceedings of the Korean Institute of Intelligent Systems Conference
• /
• 2004.10a
• /
• pp.279-282
• /
• 2004

본 논문에서는 자기저항 센서를 이용하여 자율주행 시스템에서 필요로 하는 자석의 종류에 따른 자계의 특성을 분석하였다 분석결과 거리에 따라 자계의 특성이 변화하고, 자석에 근접할수록 자계의 변화가 급격하게 나타난다. 센서가 자석에서 멀어질수록 지자계의 값에 가까워진다 또한 페라이트자석 보다 네오디뮴 자석의 자계특성이 우수함을 보였다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2008.05a
• /
• pp.882-885
• /
• 2008

무선 센서 네트워크는 저가의 한정된 자원들을 갖는 수많은 센서 노드들로 구성된다. 보편적으로 대부분의 센서들은 안전하지 않거나 제어할 수 없는 환경에 배치되며, 만일 넓은 목표 지역에 센서노드들을 무작위로 배치할 때에는 센서 노드들의 정확한 위치를 파악하기 매우 어렵다. 따라서 본 논문에서는 이러한 문제를 해결하기 위한 방안으로서 효율적인 키 분배 기법을 제안하고자 한다. 이에 제안된 기법을 통해 센서 노드들이 선-분배된 키들을 사용하여 안전한 링크를 확립한 후 근접한 이웃 노드들과 서로 정보를 교환할 수 있도록 하였다. 또한 제안된 기법에서는 센서노드의 위치 정보를 이용함으로써 노드간에 공통-키를 발견할 수 있는 확률을 높일 수 있게 하였다.

• Proceedings of the Korean Magnestics Society Conference
• /
• 2016.11a
• /
• pp.183-184
• /
• 2016

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2007.10a
• /
• pp.231-234
• /
• 2007

The magnetic sensor using electromagnetic principle. which transfers magnatic into electric. is the electric component.It has been widely applied to the industry, university and the reseach. However there are some problems. Not only the korean domestic sensor manufacture skills are still lower then the advanced manufacture's but also production of sensor is not well organized yet. Due to cahnging excitation cvurrent, excitation freq and the rate magnetic permeability core, there sometimes would be distorted phenomena or loaded phenomena which result in limited measurment range. Therefore, the signal conversion device should support to receive undistorted and nice output. This paper focuses on both the design of signal transform circuit using inductive proximity sensor and the signal transfer equipment (Z device) which detects thickness of painted material.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.35 no.5
• /
• pp.259-266
• /
• 2022

In this study, we developed a deep learning and vision sensor-based assembly performance evaluation method isfor prefabricated steel structures. The assembly parts were segmented using a modified version of the receptive field block convolution module inspired by the eccentric function of the human visual system. The quality of the assembly was evaluated by detecting the bolt holes in the segmented assembly part and calculating the bolt hole positions. To validate the performance of the evaluation, models of standard and defective assembly parts were produced using a 3D printer. The assembly part segmentation network was trained based on the 3D model images captured from a vision sensor. The sbolt hole positions in the segmented assembly image were calculated using image processing techniques, and the assembly performance evaluation using the k-nearest neighbor algorithm was verified. The experimental results show that the assembly parts were segmented with high precision, and the assembly performance based on the positions of the bolt holes in the detected assembly part was evaluated with a classification error of less than 5%.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.28 no.10
• /
• pp.810-818
• /
• 2017

This paper presents the approaching target above ground tracking based on Kalman filter applied to the proximity sensor for the active defense system. The proximity sensor located on the front of the countermeasure is not easy to detect when the anti-tank threat enters a fragment dispersion range due to limited antenna beamwidth. In addition, it is difficult for the proximity sensor to detect the anti-tank threat accurately at a terrestrial environment including various clutters. To solve these problems, this study presents the approaching target above ground tracking based on Kalman filter and applies the novel estimation method for a noise covariance matrix to improve a tracking performance. Then, a high tracking performance of Kalman filter applied the proposed noise covariance matrix is presented through field firing test results and the validity of the proposed study is examined.

• Proceedings of the Korean Information Science Society Conference
• /
• 2005.07b
• /
• pp.172-174
• /
• 2005

센서 네트워크에서 집계(aggregation) 연산은 센서 네트워크를 데이터베이스로 구현하는데 있어서 중요하게 제공되어져야 하는 서비스이다 현재 연구되고 있는 것으로 집계 연산을 센서 네트워크의 특징상으로 분류하여 근접한 결과값을 받는 것을 허용하고 집계 값을 자식노드가 부모노드로 보내는 기간을 부모노드가 자식노드에게 나누어 할당하여 센서 네트워크상에 적절히 구현하는 것에 대해 알아보고 집계 그루핑을 하는 과정에서 데이터웨어하우징 연구의 최신기술인 점진적인 덜 관리 기법을 통해 센서노드들의 평균값에 대해 새로운 값이 추가될 때 다시 모든 값을 계산하기 않고 변경된 값만 적용하여 계산함으로 좀더 에너지 효율적으로 확장하는 것을 제안하였다.

• Spatial Information Research
• /
• v.19 no.4
• /
• pp.21-31
• /
• 2011

As large scaled natural or man-made disasters being increased, the demand for rapid responses for such emergent situations also has been ever-increasing. These responses need to acquire spatial information of each individual site rapidly for more effective management of the situations. Therefore, we are developing a close-range real-time aerial monitoring system based on a low altitude unmanned helicopter. This system can acquire airborne sensory data in real-time and generate rapidly geospatial information. The system consists of two main parts: aerial and ground parts. The aerial part includes an aerial platform equipped with multi-sensor(cameras, a laser scanner, a GPS receiver, an IMU) and sensor supporting modules. The ground part includes a ground vehicle, a receiving system to receive sensory data in real-time and a processing system to generate the geospatial information rapidly. Development and testing of the individual modules and subsystems have been almost completed. Integration of the modules and subsystems is now in progress. In this paper, we w ill introduce our system, explain intermediate results, and discuss expected outcome.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.27 no.3
• /
• pp.299-306
• /
• 2016

In this paper, a vital sign sensor based on impedance variation of resonator is proposed to detect the respiration and heartbeat signals within near-field range as a function of the separation distance between resonator and subject. The sensor consists of an oscillator with a built-in planar type patch resonator, a diplexer for only pass the second harmonic frequency, amplifier, SAW filter, and RF detector. The cardiac activity of a subject such as respiration and heartbeat causes the variation of the oscillation frequency corresponding impedance variation of the resonator within near-field range. The combination of the second harmonic oscillation frequency deviation and the superior skirt frequency of the SAW filter enables the proposed sensor to extend twice detection range. The experimental results reveal that the proposed sensor placed 40 mm away from a subject can reliably detect respiration and heartbeat signals.