• The Journal of Bigdata
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• v.7 no.1
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• pp.15-27
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• 2022

In the past five years, the fatality rate of single-vehicle accidents has been 4.7 times higher than that of all accidents, so it is necessary to establish a system that can detect and respond to single-vehicle accidents immediately. The IoT(Internet of Thing)-based real-time traffic accident recognition system proposed in this study is as following. By attaching an IoT sensor which detects the impact and vehicle ingress to the guardrail, when an impact occurs to the guardrail, the image of the accident site is analyzed through artificial intelligence technology and transmitted to a rescue organization to perform quick rescue operations to damage minimization. An IoT sensor module that recognizes vehicles entering the monitoring area and detects the impact of a guardrail and an AI-based object detection module based on vehicle image data learning were implemented. In addition, a monitoring and operation module that imanages sensor information and image data in integrate was also implemented. For the validation of the system, it was confirmed that the target values were all met by measuring the shock detection transmission speed, the object detection accuracy of vehicles and people, and the sensor failure detection accuracy. In the future, we plan to apply it to actual roads to verify the validity using real data and to commercialize it. This system will contribute to improving road safety.

• Composites Research
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• v.24 no.1
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• pp.24-30
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• 2011

Low-velocity impact can cause various damages which are mostly hidden inside the laminates or occur in the opposite side. Thus, these damages cannot be easily detected by visual inspection or conventional NDT systems. And if they occurred between the scheduled NDT periods, the possibilities of extensive damages or structural failure can be higher. Due to these reasons, the built-in NDT systems such as real-time impact monitoring system are required in the near future. In this paper, we studied the impact monitoring system consist of impact location detection and damage assessment techniques for composite flat and stiffened panel. In order to acquire the impact-induced acoustic signals, four multiplexed FBG sensors and high-speed FBG interrogator were used. And for development of the impact and damage occurrence detections, the neural networks and wavelet transforms were adopted. Finally, these algorithms were embodied using MATLAB and LabVIEW software for the user-friendly interface.

• Journal of the Korea Institute of Military Science and Technology
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• v.18 no.5
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• pp.525-531
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• 2015

In this paper, a novel impact sensing device for an ESAF(Electronic Safe and Arming Fuze) is presented. An impact sensing device is mounted in front of a weapon, and it detects an impact when it crashes against a target. There are two main design requirements to enhance the firing functional reliability of the ESAF; an operational reliability and a reduced latency, which is a delay time needed for sensing the impact. The design method of the contact-type impact sensing device, which employs an FPCB(Flexible Printed Circuit Board) so it can be used other weapons, is proposed. The tests demonstrated that the design described in this work show a reduced delay time with ensuring the operational reliability.

• Proceedings of the Korean Geotechical Society Conference
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• 2007.09a
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• pp.115-123
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• 2007

설계 하중이 큰 대형 구조물의 기초로 많이 사용되는 현장타설말뚝은 현장에서 지반을 굴착하여 조립된 철근망을 삽입한 후, 콘크리트를 타설하여 제작되므로 복잡한 시공 과정과 현장의 특수한 지하수 및 지반 조건으로 인하여 현장타설말뚝의 내부에는 결함이 포함될 수 있다. 발생 가능한 대표적인 결함으로 연약한 말뚝 선단, 말뚝체 콘크리트의 품질 저하, 말뚝과 지반의 접촉 불량, 주 철근의 부식 등이 있으며, 이들 결함을 감지하기 위한 건전도 시험법으로 공대공초음파 검층, 충격반향시험, 충격응답시험, 감마-감마 검층법 등이 있다. 결함은 말뚝의 수평지지력을 감소시키며, 일반적으로 발생하는 비대칭단면 결함에 의한 응력 집중현상과 수평 하중에 의한 휨모멘트는 연직지지거동에 영향을 준다. 따라서 결함을 감지하고 평가하는 것이 현장타설말뚝의 품질관리에 있어 매우 중요하다.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2003.11a
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• pp.325-330
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• 2003

본 논문은 에폭시 지지애자에 센서를 내장하여 활선상태를 감지할 수 있는 제품개발에 관한 것이다. 개발된 제품은 KS C 3835에 따라 7.2[㎸], 12[㎸]및 24[㎸]전압용이다. 지지애자에 내장된 센서 재질은 부분방전이 발생하지 않도록 애자 재질과 동일하게 하였다. 또한 활선상태를 확인할 수 있는 현장용 및 원격용 전압표시장치를 개발하였다. 개발된 애자본체에 대해서는 부분방전, 충격내전압, 상용주파내전압, 굽힘 강도 등 성능평가를 실시하였으며 만족할 만한 결과를 얻었다. 전압표시장치에 대하여도 상용주파내전압 충격 내전압, 진동성 서지, 온도특성 등을 확인한 결과 만족할 만한 결과를 얻었다.

• Composites Research
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• v.27 no.4
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• pp.141-145
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• 2014

This paper presents a structural health monitoring method using piezoelectric paint sensor designed for an impact sensor. The piezoelectric paint sensor can be flexibly deposited onto most structural surfaces in a thin form of the paint, and measure impact signals without any external device such as a power amplifier. In this study, a composite plate having four zones coated with piezoelectric paint was used for impact monitoring test. The sensitivity of the piezoelectric paint sensor was obtained by measuring the output voltages against the impact force. In addition to the sensitivity measurement, the impact position has been also estimated by comparing the output signals of the paint sensors when the impact occurs on the specimen.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.5
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• pp.1-9
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• 2016

Railroad bridges account for 25% of the entire high-speed rail network. Railway bridges are subject to gradual structural degradation or fatigue accumulation due to consistent and repeating excitation by fast moving trains. Wireless sensing technology has opened up a new avenue for bridge health monitoring owing to its low-cost, high fidelity, and multiple sensing capability. On the other hand, measuring the transient response during train passage is quite challenging that the current wireless sensor system cannot be applied due to the intrinsic time delay of the sensor network. Therefore, this paper presents a framework for monitoring such transient responses with wireless sensing systems using 1) real-time excessive vibration monitoring through ultra-low-power MEMS accelerometers, and 2) post-event time synchronization scheme. The ultra-low power accelerometer continuously monitors the vibration and trigger network when excessive vibrations are detected. The entire network of wireless smart sensors starts sensing through triggering and the post-event time synchronization is conducted to compensate for the time error on the measured responses. The results of this study highlight the potential of detecting the impact load and triggering the entire network, as well as the effectiveness of the post-event time synchronized scheme for compensating for the time error. A numerical and experimental study was carried out to validate the proposed sensing hardware and time synchronization method.

• 전기의세계
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• v.46 no.8
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• pp.41-46
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• 1997

최근 가스절연변전소와 같은 컴팩트화된 전력설비의 사용으로 과도전압 및 충격전류의 측정시 오차를 유발시키고 장해를 가져오는 요인 중에서 가장 현저한 것은 전자계 현상이며, 이에 대한 대책과 장해의 제거방법이 검토되어야만 한다. 또한 전력기기의 사용 중에 발생되는 과도전압과 충격전류는 진행파로서 작용하여 발생지점과 측정위치에 따라 달라지므로 종래의 저항분압기, 용량성분압기로는 정확한 측정이 불가능하기 때문에 전기적 신호의 과도적 현상을 직접 감지할 수 있는 측정장치가 필요하다. 다음의 3가지 고전압 측정기술은 피측정대상에 따라 가장 적합하게 제안된 것으로 측정응답을 개선하고 전자계의 영향을 최소화함으로써 정확한 측정이 가능하다.

• Journal of Aerospace System Engineering
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• v.13 no.2
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• pp.19-25
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• 2019

To detect the impact location of a structure, the authors' group conducted a study on piezoelectric paint sensor. The piezoelectric paint sensors are used for impact detection due to their inherent characteristics: sensitivity to high-frequency signal and impact. Additionally, the paint sensor can be applied on curved and complex structures where ceramic sensor would not be applicable. Moreover it is a self-powered sensor therefore no need for an external power source. For impact localization, mosaic pattern electrodes were coated on the specimen and the impact signal obtained from any part of the electrode where the impact occurred. If we more precise impact localization is required, the electrodes should be divided into more parts and impact data acquisition conducted in all the points of the electrode. In this paper, we developed a light, cheap and simple multi-channel data acquisition system to aid in data gathering. In total four channels data acquisition have been tested using the ARM Cortex-M3.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.2
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• pp.51-56
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• 2003

The piezoelectric thin film(PVDF: polyvinylidene fluoride) sensors having good dynamic sensing charachteristics can be used to monitor low vwlocit impact on composite structures. The impact response function for composite sandwich beam was derved. The impact tests at low energy without inducing damage were performed on the instrumented drop weight impact tester. The measured signals of PVDF sensors attached on the surface of the beam agreed well with the simulated signals. And the inverse technique was applied to reconstruct the impact forces from the PVDF sensor signals. Most of reconstructed impact forces showed good agreement with the measured forces. The comparison results showed that the piezoelectric thin film sensor can be used to monitor the low velocity impact on composite sandwich structures.