• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.3162-3167
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• 2007

The OPS (Optical Particle Sensor) using light scattering from the particles (real-time measurement without physical contact to the particles) can be used for cleanroom or atmospheric environment monitoring. For particles smaller than 300 nm, the detection efficiency becomes lower as scattered light decreases with particle size. To obtain higher detection efficiency with small particles, the flow field in particle chamber and the detection volume should be designed optimally to achieve maximum scattered light from the particles. In this study, a commercial computational fluid dynamics software FLUENT was used to simulate the gas flow field and particle trajectories with various optical chamber designs for 300 nm PSL particle. For estimation of laser viewing volume, we used a commercial computational optical design program ZEMAX. The results will be a great help in the development of OPS which can measure small particles with higher detection efficiency.

• 센서학회지
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• 제28권5호
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• pp.294-298
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• 2019

Pulsed laser-based optical sensor monitoring systems for real time microplastic particle counting are proposed and developed in this study. To develop our real time monitoring system, we used a 450 nm pulsed laser and a photomultiplier with very high quantum efficiency. First, we demonstrated that the microplastic particle counting system could detect standard micro bead samples of 100, 250, and $500{\mu}m$ in river water. We then performed research concerning pulsed laser-based optical spectral sensor systems for real time microplastic monitoring. Additionally, we demonstrated that the real time microplastic remote monitoring system using LoRa communications could detect microplastic in the tap water resource protection area.

• 한국입자에어로졸학회지
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• 제14권2호
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• pp.35-40
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• 2018

Vertical particle size distribution, total particle concentration, wind velocity, temperature and humidity measurement was performed with a drone. The drone was equipped with a wind sensor, house-made optical particle count(Hy-OPC), condensation particle counter(Hy-CPC), GPS, Temperature, Relative Humidity, Pressure and communication system. Base on the wind velocity and the particle size vertical distribution measurement with drone, the particle mass flux was calculated. The vertical particle distribution showed that the particle number concentration was very strongly correlated with the relative humidity.

• 센서학회지
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• 제23권4호
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• pp.245-250
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• 2014

When the charged particle travels in transparent medium with a velocity greater than that of light in the same medium, the electromagnetic field close to the particle polarizes the medium along its path, and then the electrons in the atoms follow the waveform of the pulse which is called as Cerenkov light or radiation. This type of radiation can be easily observed in a spent fuel storage pit. In optical fibers, the Cerenkov light also can be generated due to their dielectric components. Accordingly, the radiation-induced light signals can be obtained using optical fibers without any scintillating material. In this study, to measure the intensities of Cerenkov radiation induced by gamma-rays, we have fabricated the fiber-optic Cerenkov radiation sensor system using silica optical fibers, plastic optical fibers, multi-anode photomultiplier tubes, simulated spent fuel assembly and a scanning system. To characterize the Cerenkov radiation generated in optical fibers, the intensities of Cerenkov radiation generated in the silica and plastic optical fibers were measured. Also, we measured the longitudinal distribution of gamma rays emitted from the Ir-192 isotope by using the fiber-optic Cerenkov radiation sensor system and simulated spent fuel assembly.

• 한국입자에어로졸학회지
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• 제8권1호
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• pp.9-15
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• 2012

Three different commercial particle counters were used to measure the PM2.5 particles in this study. An Aerosol Spectrometer (AS) 1.109 model of Grimm and a Particle Sensor (PS) 3030 model of HCT were compared with an Aerodynamic Particle Sizer (APS) 3321 model of TSI. The responses of these instruments were compared for four sizes ($1.0{\mu}m$, $1.5{\mu}m$, $2.0{\mu}m$ and $2.5{\mu}m$) of polystyrene latex (PSL) particles and indoor air particles of the office room. The mode diameter, particle size distribution and total particle number concentration of PSL particles were measured by each instrument. In the office room, the total particle number concentration was measured for 25 minutes. In results of particle size distribution and mode diameter, the APS 3321 (52 size-channels) was more accurate than the AS 1.109 (31 size-channels) and PS-3030 (10-szie channels) since the APS has more number of size-channels than the other instruments. However, AS 1.109 and PS-3030 provided similar results of total particle number concentration to those from the APS 3321. In results of office room test, there were no significant difference from each instrument similar to results of PSL test.

• 전기전자학회논문지
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• 제14권3호
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• pp.244-249
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• 2010

수중의 미립자 계수를 위한 Line-CCD를 이용한 수중광학 시스템을 구현하였다. 미립자 계수 측정을 위하여 680nm Laser diode를 광원으로 사용하였다. 광학시스템을 동작확인을 위해 수중 인공탱크 및 해양에서 실험을 하였다. 시스템의 상 하강 운동 시, 마이크로프로세서(FPGA)의 신호 전달(센서의 신호검출)을 통하여 미립자 계수를 알 수 있다. 시스템의 알고리즘은 또한, 깊이에 따른 압력, 온도, 계수 값을 실시간으로 분석한다. 실험을-통해 광학센서 시스템의 높은 정확도를 보여주었다. 따라서, Line-CCD를 통한 실시간 측정 가능한 수중광학 시스템을 제안 하였다.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2003년도 Proceedings of ACRS 2003 ISRS
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• pp.667-669
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• 2003

A bio-optical model was developed specific for turbid and shallow waters. Special studies were carried out to estimate absorption and scattering properties as well as backscattering probability of suspended matter. The inversion of bio-optical model allows for direct retrieval of turbidity and chlorophyll- a from the visible-near infrared (VNIR) range sensor. Time-series satellite imagery from ASTER AM-1 sensor, were used to monitor the Laguna de Bay water quality condition. Spatial distribution of temperature for the lake was extracted from the thermal infrared (TIR) sensor. Corresponding field surveys were conducted to parameterize the bio -optical model. In-situ measurements include suspended particle and chlorophyll-a concentrations profiles from nephelometric devices and processing of water samples. Hyperspectral measurements were used to validate results of the bio -optical model and satellite- based estimation. This study provides a theoretical basis and a practical illustration of applying space- based measurements on an operational basis.

• Journal of Biosystems Engineering
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• 제23권5호
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• pp.481-490
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• 1998

A computer vision system to measure low flow rate of solid particles was developed and tested to examine its performance with various sized 7 kinds of seeds, perilla, mung bean, paddy, small red bean, black soybean, Cuba bean and small potato tuber. The test was performed for two types of particle flow, continuous and discontinuous. For the continuous flow tested with perilla, mung bean and paddy, the tests resulted correlation coefficients for the flow rates measured by the computer vision and direct method about 0.98. Average errors of the computer vision measurement were in a range of 6∼9%. For the discontinuous flow tested with small red bean, black soybean, Cuba bean and small potato tuber, the tests resulted correlation coefficients for the flow rates measured by the computer vision and direct method 0.98∼0.99. Average errors of the computer vision measurement were in a range of 5∼10%. Performance of the computer vision system was compared with that of the conventional optical sensor to count particles in discontinuous flow. The comparison was done with black soybean, Cuba bean and small potato tuber, and resulted that the computer vision has much better performance than the optical sensor in a sense of precision of the measurement.

• 한국멀티미디어학회논문지
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• 제21권1호
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• pp.51-60
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• 2018

We present a real-time interactive particle-art with human motion based on computer vision techniques. We used computer vision techniques to reduce the number of equipments that required for media art appreciations. We analyze pros and cons of various computer vision methods that can adapted to interactive digital media art. In our system, background subtraction is applied to search an audience. The audience image is changed into particles with grid cells. Optical flow is used to detect the motion of the audience and create particle effects. Also we define a virtual button for interaction. This paper introduces a series of computer vision modules to build the interactive digital media art contents which can be easily configurated with a camera sensor.

• 센서학회지
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• 제17권4호
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• pp.317-324
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• 2008

This paper presents an optical doppler tomography(ODT) system using a speaker as a method to achieve depth measurement in a flowing sample. The use of the speaker provides easy implementation with a low cost. The nonlinear characteristics of the speaker has hindered its adaptation because it produces inconsistent fringe frequencies at different depths. This paper reports an adaptive algorithm to compensate the nonlinear characteristics, and could, resultantly, acquire the Doppler frequency shift caused by the sample. The experiment utilizes a flowing scattering particle solution in a capillary tube at a certain flow rate. The Doppler frequency profile over the lumen was calculated by using spectrogram method. and we obtained the velocity image of the sample.