• The Journal of the Korea institute of electronic communication sciences
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• v.17 no.5
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• pp.873-882
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• 2022

In this paper, we studied the voice recognition system kiosk for convenience, thinking that the kiosk widely used in modern society should compensate for the inconvenience of using by the visually impaired. Using ultrasonic sensor and PIR(Passive Infrared), it recognizes the visually impaired within the range of 80cm-40cm, introduces the kiosk through the MP3 module and induces them to come closer. Also, when the visually impaired within 40cm is recognized, the product description and order are guided through the MP3 module. A recording-based data voice recognition system and a kiosk that outputs desired items through servo motors were studied. A kiosk for the convenience of the visually impaired was manufactured through operation and optimization experiments of PIR, ultrasonic, voice recognition, and shock sensor for the manufactured voice recognition kiosk. Finally, it was confirmed that security can be strengthened by using shock sensors and emergency bells to enhance security.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.32 no.7
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• pp.37-42
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• 2004

In order to monitor the impact locations in smart structures, multipoint ultrasonic sensors are to be employed. In this study, a multiplexing demodulator with wide dynamic range was proposed to detect the impact locations using FBG sensors, and a stabilization controlling system was also developed for the maintenance of maximum sensitivity of sensors. Two FBG sensors were attached on the bottom side of the aluminum beam specimen and low velocity impact tests were performed to detect the one-dimensional impact locations. As a result, multiplexed in-line FBG sensors could detect the moment of impact precisely, and found the impact locations with the average location error below 0.58mm.

• Composites Research
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• v.24 no.6
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• pp.49-55
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• 2011

The use of advanced composite materials in main structures of military and civil aircraft has been increased rapidly because of their considerable metals in high specific strength and stiffness. However, the mechanical properties of composite materials may severely degrade in the presence of damage. Especially, the high-velocity impact such as a hailstorm, and a small piece of tire or stone during high taxing, can cause considerable damage to the structures and sub-system in spite of a very small mass. However, it is not easy to detect the damage in composite plates using a single sensor or any conventional methods. In this paper, the PVDF sensors and AE sensors were used for monitoring high-velocity impact damage initiation and propagation in composite laminates. The WT(wavelet transform) is used to decompose the sensor signals. In the PVDF sensor and AE sensor signal analysis, amounts of high-frequency signals are increased when the impact energy is increased. PVDF sensor and AE sensor signal appeared similar results. This study shows how various sensing techniques can be used to characterize high-velocity impact damage of advanced composite laminates.

• Journal of the Korean Society for Nondestructive Testing
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• v.26 no.4
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• pp.255-259
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• 2006

For the intruder detection, a buried fiber-optic sensor based on fiber-optic Mach-Zehnder interferometer is demonstrated. We buried the sensor arm in a styrene board and exerted pressure on it. The pressure-induced deformation speed has almost linear relationship with the output frequencies of the interference signals, and about 4.25 Hz frequency change per 0.01m/s was obtained. Also it has been shown that the amplitude of frequency component increases according to the weight of mass.

• 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 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.

• 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.

• 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.

• Proceedings of the Korea Information Processing Society Conference
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• 2021.11a
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• pp.167-169
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• 2021

본 논문에서는 아두이노와 라즈베리 파이를 기반으로 연동한 스마트 금고 시스템을 제안한다. 기존의 금고와 달리 보안성과 편리성의 취약점을 해결하도록 했다. 아두이노와 라즈베리 파이 기반의 다양한 센서를 이용해 스마트 금고의 보안성과 편리성을 높이도록 제안한다. 구현을 위해 지문인식 센서, RFID 센서, 키 패드, GPS, 충격감지 센서, 파이 카메라, PIR 센서를 사용한다. 또한, 스마트 금고 상태와 조작을 할 수 있는 어플리케이션을 제작해 편리성을 높이도록 했다. 금고 프로토 타입의 외부 재질은 3D 프린팅을 이용하여 제작을 했다.