• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.11
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• pp.1706-1712
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• 2012

The Beta-ray absorption method (BAM) gives a good solution for measuring the mass concentration of atmospheric particles(PM10 and PM2.5). To determine particular matters (PM) concentration, a ratio of the number of detected beta-ray intensity passing through the clean filter and the dust-sampled filter is used. These intensity data measured in air pollution monitoring such as PM10 and PM2.5 usually contained the additive noise(thermal noise, power supply noise and etc.). Therefore, the estimation performance of mass concentration can be deteriorated by these noises. In this paper, we present a new noise reduction method that is essentially required to develope an automatic continuous PM monitoring system using beta-ray absorption method. By combining the block data averaging technique and curve fitting, in the proposed method, the additive noise can be reduced in the measured data. To evaluate the performance of the proposed method, computer simulations were performed with computer generated signals as the input.

• Particle and aerosol research
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• v.5 no.2
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• pp.53-62
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• 2009

In this study, the continuous monitoring of the concentration of PM-10 atmospheric particulate matter using beta ray attenuation method was compared with gravimetric method from September, 2006 to August, 2007. On the effects of the PM-10 concentration and mass difference by relative humidity and precipitation were considered. The result showed that the measurement error between beta ray method and gravimetric method are within -3~6% in average, which means PM-10 concentration data with beta ray method are relatively comparable. The current study also shows that the high PM-10 concentration events are mainly due to haze, Asian dust, and high relative humidity and the PM-10 mass concentration is closely related with relative humidity and precipitation events. Based on daily mean data, the PM-10 increases as relative humidity increases up to 70~80%, then decreases over 80% due to the precipitation. However, the distinct measurement discrepancy was not shown between beta ray method and gravimetric method based on current results. Consequently, this study shows that the collocated measurement in different instrument is essential in order to quantify the accuracy of PM-10. Furthermore, the more comprehensive and spatially distributed comparison is needed and this is remained for future study.

• Journal of Korean Society for Atmospheric Environment
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• v.14 no.1
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• pp.1-10
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• 1998

Relationships between TSP and PM10 concentrations were evaluated using their respective data sets collected from Taegu and Kyeungsan areas during the period of December 1993 to November 1994. The collection of data was made using the gravimetric and $\beta$-ray absorption ($\beta$-MPM) methods for 7 days of every month from three urban sites in Taegu and one suburban site in Kyeungsan. Correlation coefficients between TSP and PM10 concentrations for these four sampling sites were found in the range of 0.85 $\sim$ 0.96. Correlation analysis was also conducted for $\beta$-PM concentration data that were measured only from the residential and commercial sites. The correlation coefficients between TSP and $\beta$-PM concentrations were 0.9 in the residential site and 0.8 in the commercial site. By contrast, the correlation coefficients between PM10 $\beta$-PM concentrations were almost identical for both the residential and commercial sites with a value of 0.88. The mean ratio for PM10 to TSP concentrations for all sites was appeared to be 0.68. The analysis of seasonal trends in PM10/TSP ratios showed that the contribution of PM10 to TSP concentrations was more significant during winter (0.70 $\sim$ 0.75) than during summer (0.61 $\sim$ 0.68). The results of this study may provide empirical informations on the compatability of aerosol data measured by different sampling methods.

• Journal of Korean Society for Atmospheric Environment
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• v.26 no.5
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• pp.533-542
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• 2010

The $PM_{10}$ concentrations in the underground should be monitored for the health of commuters on the underground subway system. Seoul Metro and Seoul Metropolitan Rapid Transit Corporation are measuring several air pollutants regularly. As for the measurement of $PM_{10}$ concentrations, instruments based on $\beta$-ray absorption method and gravimetric methods are being used. But the instruments using gravimetric method give us 20-hour-average data and the $\beta$-ray instruments can measure the $PM_{10}$ concentration every one hour. In order to keep the $PM_{10}$ concentrations under a healthy condition, the air quality of the underground platform and tunnels should be monitored and controlled continuously. The $PM_{10}$ instruments using light scattering method can measure the $PM_{10}$ concentrations every less than one minute. However, the reliability of the instruments using light scattering method is still not proved. The purpose of this work is to study the reliability of the instruments using light scattering method to measure the $PM_{10}$ concentrations continuously in the underground platforms. One instrument using $\beta$-ray absorption method and two different instruments using light scattering method (LSM1, LSM2) were placed at the platform of the Jegi station of Seoul metro line Number 1 for 10 days. The correlation between the $\beta$-ray instrument and the LSM2 ($r^2$=0.732) was higher than that between the $\beta$-ray instrument and the LSM1 ($r^2$=0.393). Thus the LSM2 was chosen for further analysis. Three different regression analysis methods were tested: Linear regression analysis, Nonlinear regression analysis and Orthogonal regression analysis. When the instruments using light scattering method were used, the data measured these instruments have to be converted to actual $PM_{10}$ concentrations using some factors. With these analyses, the factors could be calculated successfully as linear and nonlinear forms with respect to the data. And the orthogonal regression analysis was performed better than the ordinary least squares method by 28.45% reduction of RMSE. These findings propose that the instruments using light scattering method light scattering method can be used to measure and control the $PM_{10}$ concentrations of the underground subway stations.

• Journal of Sensor Science and Technology
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• v.25 no.5
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• pp.333-336
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• 2016

In this study, a beta monitoring sensor was developed as a part of basic research for quantitative beta monitoring underwater, and its performance was evaluated using a calibration source. A beta detection sensor was manufactured by using SiPM(silicon photomultiplier) and $CaF_2$:Eu, YAG:Ce, YAP:Ce scintillator. A large-area light guide was introduced to improve beta-ray detection efficiency. As calibration sources, the Beta source $^{90}Sr$, which is the main fission product of a nuclear accident, and the gamma source $^{137}Cs$ are used. In the performance evaluation, it is confirmed that scintillator $CaF_2:Eu$ gives the highest beta-ray detection response. Compared to gamma ray, beta-ray detection responsivity and detection efficiency are verified. Therefore, this study is expected to contribute to basic research in the development of an underwater beta-ray monitoring system.

• Advances in environmental research
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• v.1 no.1
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• pp.69-82
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• 2012

Based on the measurement data of the particulate matter with an aerodynamic diameter of less than or equal to a nominal 10 ${\mu}m$ (PM10) by the ${\beta}$-ray absorption method (BAM) equipped with an inlet heater and the gravimetric method (GMM) at two coastal sites in Korea, the optimal inlet heater temperature was estimated. By using a gas/particle equilibrium model, Simulating Composition of Atmospheric Particles at Equilibrium 2 (SCAPE2), water content in aerosols was estimated with varying temperature to find the optimal temperature increase to make the PM10 concentration by BAM comparable to that by GMM. It was estimated that the heated air temperature inside the BAM should be increased up to $35{\sim}45^{\circ}C$ at both sites. At this temperature range, evaporation of volatile aerosol components was minor. Similar ($30{\sim}50^{\circ}C$) temperature range was also obtained from the calculation based on the absolute humidity which changed with ambient absolute humidity and chemical composition of hygroscopic species.

• Particle and aerosol research
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• v.8 no.3
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• pp.111-120
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• 2012

In Daegu, a road cleaning system was constructed in the central part of the city and has been operated from April, 2011. We evaluated the effect of the system on the concentration of $PM_{10}$ at a roadside monitoring site. The ambient $PM_{10}$ concentration data were logged every 1 min for a period of 20 weeks from May to October, 2011, by means of light scattering method, and then every 5 min data were used in the statistical analysis. The measured data were verified by comparing them with beta-ray data obtained at the same site. Correlation coefficient between the two groups was highly significant (r=0.79), though the absolute levels of light scattering data appeared to be approximately 2.8 times higher than the beta-ray data. Diurnal, daily, weekly, and monthly variations of $PM_{10}$ data did not show any evidence of decreasing effect owing to the clean road system. A comparison of roadside $PM_{10}$ data with non-roadside data also revealed very similar pattern, implying the variation of the $PM_{10}$ concentrations is mainly affected by the traffic conditions near the monitoring site. However, if the operating conditions of the clean road system can be improved, i.e. increasing the frequency and duration of water cleaning, the road cleaning effect may improve the air quality indirectly by means of removing the resuspended particles from the road.

• Progress in Medical Physics
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• v.3 no.1
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• pp.9-18
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• 1992

In this study, beta-eucryptite is fabricated and the thermal parameters of this material have been investigated. The thermoluminescence from 4MeV X-ray irradiated beta-eucryptite have been measured over the temperature range of 300K-600K. Thermoluminescence curve from X-ray irradiated beta-eucryptite shows five peaks located at 342K, 392K, 438K, 474K, and 527K. $\tau$, $\delta$ and $\omega$ of peak at 527K are 35K, 39K and 74K, respectively and this peak is found to be 2nd order kinetics. The activation energy of peak shape method is calculated to be 1.03eV and the frequency factor for 527K curve is calculated to be 3.9x10$\^$8/sec$\^$-1/. Based on the various heating rates methods, the activation energy of the peak is computed to be 1.02${\pm}$0.05eV that is similar to 1.19${\pm}$0.03eV of initial rise method. The linearity of thermoluminescence intensity and radiation flux is valid up to 50Gy and beyond higher dose the supralinearity and saturation come out.

• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.720-724
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• 2008

The purpose of this study is to evaluate the PM10 removal efficiencies of an Air-washer and an Ultrasonic humidifier by mock-up experiments. The concentrations of PM10 were measured at 5 minute intervals using $\beta$-Ray method. The average PM10 removal efficiency of the Air-washer was 79.8%, while the PM10 concentrations increased with the operation of Ultrasonic humidifier. In the case of operating the Air-washer, the R.H(Relative Humidity) level of the test room was maintained at around 45%, regardless of initial R.H condition. The R.H of the test room with Ultrasonic humidifier was influenced by the initial R.H condition.

• Current Optics and Photonics
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• v.3 no.2
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• pp.154-163
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• 2019

In this study, we developed an optical sighting system capable of shooting at a long-distance target by operating a digital gyro mirror composed of a gyro sensor and an FSM. The optical sighting system consists of a reticle part, a digital gyro mirror (FSM), a parallax correction lens, a reticle-ray reflection mirror, and a partial reflection window. In order to obtain the optimal volume and to calculate the leading angle range according to the driving angle of the FSM, a calculation program using Euler rotation angles and a three-dimensional reflection matrix was developed. With this program we have confirmed that the horizontal leading angle of the developed optical sighting system can be implemented under about ${\pm}8^{\circ}$ for the maximum horizontal driving angle (${\beta}={\pm}12.5^{\circ}$) of the current FSM. Also, if the ${\beta}$ horizontal driving angle of the FSM is under about ${\pm}15.5^{\circ}$, it can be confirmed that the horizontal direction leading angle can be under ${\pm}10.0^{\circ}$. If diagonal leading angles are allowed, we confirmed that we can achieve a diagonal leading angle of ${\pm}10.0^{\circ}$ with a vertical driving angle ${\alpha}$ of ${\pm}7.1^{\circ}$ and horizontal driving angle ${\beta}$ of ${\pm}12.5^{\circ}$.