• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1994년도 춘계학술대회 논문집
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• pp.425-428
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• 1994

Non-uniform minute deformation of a cylinderical workpiece resulted from the heat treatment process prior to the grinding makes it diffeclt to control the approaching feedrate of a grinding wheelto a workpiece optimallywithout on-site detection of the grinding states in the plunge grinding. The 4-stage model of the plunge grinding process is proposed according to the state of contact between grinding wheel and workpiece ; precontact, partial contact, entire contact and spark-out. Despite of being scrious to the precision of workpiece finished, the duration of spark-out is determined empirically. The purpose of this research is to develop a monitoring/control system for saving non- production time and setting the optimal spark-out time based on sensor information in the plunge grinding using AE and ultra sonic sensor.

• 한국정보통신학회논문지
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• 제19권9호
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• pp.2087-2092
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• 2015

산업이 발전함에 따라 제조업 및 서비스 제품 등 다양한 분야에 열전달 장치 및 열전달 시스템이 활용되고 있다. 열전달 시스템의 자동화 및 모니터링 시스템을 통하여 환경을 관리하기 위해서는 온도 측정이 필요한 대상물의 직접적인 온도 및 측정 대상물의 주위 온도에 대한 계측이 필수요소라 할 수 있다. 특히, 이러한 온도 측정에 관한 두 가지 요소에 대하여 본 논문에서는 비접촉온도센서를 활용하여 온도 계측이 필요한 대상물에 센스를 직접 접촉하지 않고 대상물의 표면 온도를 계측할 수 있는 시스템과 대상물 주위 온도를 계측할 수 있는 모듈을 소형 MCU(microcontroller unit) 기반으로 설계하여 계측된 온도 데이터를 USN(Ubiquitous Sensor Network)기반의 지그비(ZigBee) 통신을 활용하여 온도 모니터링 시스템을 제시하고자 한다. 본 논문에서는 대상물의 온도와 주위 온도에 관한 정보를 계측하기 위하여 비접촉온도센서를 활용하여 대상물의 표면 온도 및 주위 온도를 계측할 수 있는 펌웨어 기반의 시스템을 설계하였다. 또한, 계측된 온도 정보 데이터를 지그비 통신을 기반으로 원격으로 온도 데이터를 모니터링 할 수 있는 시스템을 제시하고자 한다.

• Tribology and Lubricants
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• 제11권5호
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• pp.40-46
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• 1995

This study concerns the design and development of the non-vibrating capacitance probe which could be used as a non-contact sensor for tribological wear. This device detects surface charge through temporal variation in the work function of a material. Experiments are performed to demonstrate the operation of the probe on a roating aluminum shaft. The reference electrode of the probe, made of lead, is placed adjacent (< 1.25-mm distance) to the shaft. Both surfaces which are electrically connected, form a capacitor. An artificial spatial variation in the work function is imposed on the shaft surface by coating a segment along the shaft circumference with a colloidal silver paint. As the shaft rotates, the reference electode senses changing contact potential difference with the shaft surface, owing to compositional variation. Temporal variation in the contact potential difference induces a current through the electrical connection. This current is amplified and converted to a voltage signal by an electoronic circuit with an operational amplifier. The magnitude of the signal decreases asymptotically with the electrode-shaft distance and increases linearly with the rotational frequency. These results are consistent with the theoretical model. Potential applications of the probe on wear monitoring are proposed.

• Smart Structures and Systems
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• 제24권5호
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• pp.617-630
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• 2019

Currently most of the vision-based structural identification research focus either on structural input (vehicle location) estimation or on structural output (structural displacement and strain responses) estimation. The structural condition assessment at global level just with the vision-based structural output cannot give a normalized response irrespective of the type and/or load configurations of the vehicles. Combining the vision-based structural input and the structural output from non-contact sensors overcomes the disadvantage given above, while reducing cost, time, labor force including cable wiring work. In conventional traffic monitoring, sometimes traffic closure is essential for bridge structures, which may cause other severe problems such as traffic jams and accidents. In this study, a completely non-contact structural identification system is proposed, and the system mainly targets the identification of bridge unit influence line (UIL) under operational traffic. Both the structural input (vehicle location information) and output (displacement responses) are obtained by only using cameras and computer vision techniques. Multiple cameras are synchronized by audio signal pattern recognition. The proposed system is verified with a laboratory experiment on a scaled bridge model under a small moving truck load and a field application on a footbridge on campus under a moving golf cart load. The UILs are successfully identified in both bridge cases. The pedestrian loads are also estimated with the extracted UIL and the predicted weights of pedestrians are observed to be in acceptable ranges.

• 한국엔터테인먼트산업학회논문지
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• 제15권1호
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• pp.27-38
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• 2021

팬데믹으로 인한 사회적 거리 두기 시작으로 비접촉 사회를 형성하였다. 접촉을 제한하는 언 콘택트 시대가 도달함으로써 우리 사회 및 경제생활뿐 아니라 교육 활동에도 지대한 영향을 미치고 있다. 이 같은 감염병 사태에 대응하여 대학을 비롯한 모든 교육 기관들은 비대면 온라인 수업을 시행하였다. 특히, 예체능을 비롯한 실무 형태 위주의 학과 수업들은 비대면으로 인한 제한된 환경으로 많은 어려움을 겪고 있다. 가창 수업은 주로 1:1 대면 개인지도 또는 단체 수업 방법에서 비접촉 시대로 시행된 비대면 수업 전환으로 과도기를 경험하고 있다. 전통적인 교육 방식에 머물러 있던 국내 학교 현장에서 코로나 19 이후 비접촉 시대를 맞이하여 기술을 혁신하는 에듀테크가 본격화 할 것으로 전망되는 가운데 가속화된 교육 혁신에 대비하여 비대면 실기 수업이 나아갈 방향에 대해 살펴볼 필요가 있다. 본 연구는 언택트 가창 수업 방법연구를 위해 먼저 비접촉 사회로 인한 국내 대학 현황과 가창 수업 형태를 살펴본다. 그 사례 연구로 가창 수업 방법을 제시하고 그 수업을 수강한 학생들과 교수들의 설문 조사와 인터뷰를 진행하였다. 그와 더불어 비대면 가창 수업의 장단점을 조사하고, 만족하는 수업 방법의 연구결과로 '가창 녹화 모니터링 및 선행학습', '즉각적인 영상자료 보컬 분석 및 보충 음악 이론'이 두 가지 구성요소를 도출할 수 있었다. 시대적 변화와 함께 효과적인 비접촉 가창 수업을 위해서는 비대면 가창 수업의 문제점들을 보완하고, 새로운 비접촉 가창 수업 방법에 관한 지속적인 연구와 시스템 구축이 더욱 마련되어야 한다.

• Journal of Advanced Marine Engineering and Technology
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• 제39권10호
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• pp.1011-1016
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• 2015

Gas piping systems in power plants and factories are always influenced by the mechanical vibrations of rotational machines such as pumps, blowers, and compressors. Unusual vibrations in a gas piping system influence possible leakages of liquids or gases, which can lead to large explosive accidents. Real-time measurements of unusual vibrations in piping systems in situ prohibit them from being possible leakages owing to the repeated fatigue of vibrations. In this paper, a non-contact 3-dimensional measurement system that can detect the vibrations of a solid body and monitor its vibrational modes is introduced. To detect the displacements of a body, a stereoscopic camera system is used, through which the major vibration types of solid bodies (such as X-axis-major, Y-axis-major, and Z-axis-major vibrations) can be monitored. In order to judge the vibration types, an artificial neural network is used. The measurement system consists of a host computer, stereoscopic camera system (two-camera system, high-speed high-resolution camera), and a measurement target. Through practical application on a flat plate, the measured data from the non-contact measurement system showed good agreement with those from the original vibration mode produced by an accelerator.

• 터널과지하공간
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• 제20권3호
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• pp.207-216
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• 2010

국내에서 현재까지 개발되어 적용된 낙석감지 시스템은 주로 낙석방지망에 와이어나 광섬유, 또는 경사계를 설치하여 와이어의 장력을 측정하거나 낙석 발생에 의해 와이어 단락이나 낙석방지망의 변형 또는 기울어지는 것을 감지하여 낙석을 확인하는 시스템들이다. 이러한 방법들은 낙석방지망이 먼저 설치되어 있어야 하며 낙석이 발생하면 일반적으로 관련 센서와 와이어 등에 대하여 재정비를 해야 다시 원래의 기능을 수행할 수 있게 된다. 이러한 단점을 해결하기 위하여 본 연구에서는 장력이나 변위 측정방식이 아니라 광센서와 카메라가 설치된 구역에서 낙석 통과 여부를 비접촉 방식으로 실시간 감지가 가능하도록 하는 방법을 제시하고 이를 구현하였다. 개발된 시스템을 실내실험 및 현장 적용을 한 결과 낙석 관련 정보를 효과적으로 수집하고 분석할 수 있었다. 또한 낙석 감지 전후 획득한 2장의 사진에 대하여 lighten 또는 difference 연산을 적용할 경우 낙석의 크기와 이동 방향에 대한 개략적 평가가 가능하였다.

• 전기학회논문지
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• 제58권10호
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• pp.2071-2078
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• 2009

In this paper, we proposed a non-contact respiration measurement system with ultrasonic proximity sensor. Ultrasonic proximity sensor approach of respiration measurement which respiration signatures and rates can be derived in real-time for long-term monitoring is presented. 240 kHz ultrasonic sensor has been applied for the proposed measurement system. The time of flight of sound wave between the transmitted signal and received signal have been used for a respiration measurement from abdominal area. Respiration rates measured with the ultrasonic proximity sensor were compared with those measured with standard techniques on 5 human subjects. Accurate measurement of respiration rate is shown from the 50 cm measurement distance. The data from the method comparison study is used to confirm the performance of the proposed measurement system. The current version of respiratory rate detection system using ultrasonic can successfully measure respiration rate. The proposed measurement method could be used for monitoring unconscious persons from a relatively close range, avoiding the need to apply electrodes or other sensors in the correct position and to wire the subject to the monitor. Monitoring respiration using ultrasonic sensor offers a promising possibility of non-contact measurement of respiration rates. Especially, this technology offers a potentially inexpensive implementation that could extend applications to consumer home-healthcare and mobile-healthcare products. Further advances in the sensor design, system design and signal processing can increase the range of the measurement and quality of the rate-finding for broadening the potential application areas of this technology.

• Journal of Multimedia Information System
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• 제8권1호
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• pp.1-10
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• 2021

Heart Rate is a crucial physiological parameter that provides basic information about the state of the human body in the cardiovascular system, as well as in medical diagnostics and fitness assessments. At present day, it has been demonstrated that facial video-based photoplethysmographic signal captured using a low-cost RGB camera is possible to retrieve remote heart rate. Traditional heart rate measurement is mostly obtained by direct contact with the human body, therefore, it can result inconvenient for long-term measurement due to the discomfort that it causes to the subject. In this paper, we propose a non-contact-based remote heart rate measuring approach of the subject which depends on the color intensity variation of the subject's facial skin. The proposed method is applied in two regions of the subject's face, forehead and cheeks. For this, three different algorithms are used to measure the heart rate. i.e., Fast Fourier Transform (FFT), Independent Component Analysis (ICA) and Principal Component Analysis (PCA). The average accuracy for the three algorithms utilizing the proposed method was 89.25% in both regions. It is also noteworthy that the FastICA algorithm showed a higher average accuracy of more than 92% in both regions. The proposed method obtained 1.94% higher average accuracy than the traditional method based on average color value.

• 한국전기전자재료학회논문지
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• 제30권10호
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• pp.677-682
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• 2017

Lamination is used extensively in various industries. The type of lamination applied to the material depends on the precision level required, which varies for materials needed for everyday use, materials used in high-tech industries, and processes employed to fabricate finished products. Especially in hot lamination, the distribution of the surface temperature of the heating roller is very important to avoid the generation of internal bubbles and ensure flatness of the attached materials, and thus maintain a good standard of quality and productivity. In this study, we have developed a system to monitor the surface temperature of the heating rollerby applying a heterogeneous controller and a non - contact temperature sensor. This monitoring system accurately measures the surface temperature of the heating roller and applies the RS485 MODBUS communication method for easy expansion. Using this system, a laminated prototype was fabricated, and its efficacy for non-contact temperature sensor calibration, Ethernet IP communication, stoppage of the heating roller, and determination of temperature distribution with rotation was examined for its potential usage in industries.