• Analytical Science and Technology
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• v.16 no.1
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• pp.1-11
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• 2003

This research examined the presence of hazardous materials in chemical workplace field using an integrated chemical/biological monitoring. Chemical workplace field air for volatile organic compounds (VOCs) analysis was collected using a collection tube packed with Tena.x TA adsorbent 400 mg. Workplace field air samples were analyzed by gas chromatography/mass spectrometry (GC/MS). Simultaneously, Tradescantia BNL 4430 clone was exposed in situ to monitor hazardous materials in chemical workplace field. GC/MS analysis showed the presence of various VOCs such as trichloroethylene, toluene, ethylbenzene, (m,p,o)-xylenes, styrene, 1,3,5-trimethylbenzene, and 1,2,4-trimethylbenzene. The results showed that in situ monitoring of VOCs with the Tradescantia-micronucleus (Trad-MCN) assay gave positive results in chemical workplace field and negative response at outdoor air. In conclusion, inhalation of these field air by workers may affect chronic demage to their health by inducing micronuclei formation in Tradescantia pollen mother cells. The combination of chemical/biological monitoring is very effective to evaluate hazardous materials in workplace field and can be alternatively used for screening hazardous materials.

• Progress in Superconductivity
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• v.14 no.1
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• pp.45-51
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• 2012

Microwave metrology for the thickness of metallic or superconductive films provides a new way to measure the film thickness in a non-invasive way by using microwave resonators, with the measurement accuracy affected by standard uncertainties in the resonator quality factor, temperature-dependent resonant frequency and the dimensions of the resonators. Here we study effects of the standard uncertainty in the thickness, $t_{cal}$, of a calibration $YBa_2Cu_3O_{7-{\delta}}$ (YBCO) film on the measured thicknesses, $t_{RF}$, by using a ~ 40 GHz microwave resonator. For the study, we used five YBCO films having the thicknesses of 70 - 360 nm, for which relative standard uncertainties in $t_{RF}$ due to that in $t_{cal}$ are obtained. The standard uncertainty in $t_{cal}$ was determined with the surface roughness of the film taken into account. It appeared that relative standard uncertainty in $t_{cal}$ significantly affects the $t_{RF}$ values, with the values of 1% (5%) in the former resulting in those of 1-2% (5-9%) for the latter at 10 K. Our results show that, for realizing relative standard uncertainties less than 5% in $t_{RF}$ for all the YBCO films, the surface roughness of the calibration films should be small enough to realize a relative standard uncertainty of less than 2.7% in $t_{cal}$.

• Korean Journal of Optics and Photonics
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• v.31 no.1
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• pp.13-19
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• 2020

To measure underwater acoustics using a fiber-optic Sagnac interferometric sensor, the sensitivities of ring-type probes are investigated by theoretical and experimental studies. A ring-type probe was fabricated by packaging a single-mode fiber wound around an acrylate cylinder of diameter 5 cm with epoxy bond. The probes were prepared as A-type, which was packaged with 46.84 m of sensing optical fiber, and B-type, which was packaged with 112.22 m of sensing fiber. The underwater acoustic test was performed at frequencies of 50, 70, and 90 kHz, and over a range of acoustic pressure of 20-100 Pa, to study the sensitivity. A commercial acoustic generator was located 1 m from the acoustic sensor, such as the ring-type probe or a commercial acoustic sensor. From the experimental test, the acoustic sensitivity of the ring-type probe had different values due to acoustic frequencies, unlike the theoretical prediction. Therefore, the experimental sensitivities were averaged for comparison to the theoretical values. These averaged sensitivities are 25.48 × 10^-5 rad/Pa for the A-type probe and 60.79 × 10^-5 rad/Pa for the B-type probe. The correction coefficient of Young's modulus c was determined to be 0.35.

• Journal of the Korean Institute of Gas
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• v.22 no.6
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• pp.109-122
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• 2018

Domestic LPG meters are being tested for LPG quantification in accordance with the "Measures Act". The LPG meter is re-tested every three years in accordance with the "Enforcement Decree of the Measures Act". The maximum permissible error within the test is within ${\pm}1.0%$, and the tolerance is within ${\pm}1.5%$. For the quantitative measurement of LPG, a hydrometer for LPG, a balance, and a pressure vessel are used. The volume of LPG varies in depending on the temperature and pressure. The current quantitative measurement method of LPG requires the measurement of temperature, pressure and density in order to determine the volume of LPG, respectively, and some equipments are needed accordingly. Coriolis mass flowmeter, on the other hand, measure the mass flow, density and temperature at the same time, and can be converted and calculated to the required values using a computer program, also it is widely applied in the industrial field. In this study, the volume of LPG was measured using a Coriolis mass flowmeter as a basic study of LPG quantitative measurement. In addition, it is shown that it is possible to apply for the LPG quantitative measurement using the Coriolis mass flowmeter by comparing it with the conventional LPG quantitative measurement method.

• Journal of Broadcast Engineering
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• v.28 no.1
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• pp.55-78
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• 2023

The fringe pattern obtained through a DHM (Digital Holographic Microscopy) contains the thickness information of the sample. However, there is a disadvantage that the data capacity is large. Therefore, a compression method that can reduce the data size while minimizing damage to the thickness information of the sample contained in the fringe pattern is required. This paper presents the phase compression method and confirmed through experiments that the phase compression method is more efficient that the fringe pattern compression method used in JPEG Pleno Holography. As a result of evaluation using RMSE, BD-Rate and PSNR the phase compression method showed up to 92.39% improvement in performance than the fringe pattern compression method. In addition, experiment were conducted under various conditions to compare and analyze the compression performance for each condition. In the case of the fringe pattern compression method, it includes not only the phase information for calculating the thickness of the sample but also other information, whereas the phase compression method compresses only the phase information after removing unnecessary information from the fringe pattern. It is judged to have high performance.

• The Journal of Advanced Prosthodontics
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• v.15 no.3
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• pp.155-170
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• 2023

PURPOSE. This study aims to clinically compare the fitness and trueness of zirconia crowns fabricated by different combinations of open CAD-CAM systems. MATERIALS AND METHODS. Total of 40 patients were enrolled in this study, and 9 different zirconia crowns were prepared per patient. Each crown was made through the cross-application of 3 different design software (EZIS VR, 3Shape Dental System, Exocad) with 3 different processing devices (Aegis HM, Trione Z, Motion 2). The marginal gap, absolute marginal discrepancy, internal gap(axial, line angle, occlusal) by a silicone replica technique were measured to compare the fit of the crown. The scanned inner and outer surfaces of the crowns were compared to CAD data using 3D metrology software to evaluate trueness. RESULTS. There were significant differences in the marginal gap, absolute marginal discrepancy, axial and line angle internal gap among the groups (P < .05) in the comparison of fit. There was no statistically significant difference among the groups in terms of occlusal internal gap. The trueness ranged from 36.19 to 43.78 ㎛ but there was no statistically significant difference within the groups (P > .05). CONCLUSION. All 9 groups showed clinically acceptable level of marginal gaps ranging from 74.26 to 112.20 ㎛ in terms of fit comparison. In the comparison of trueness, no significant difference within each group was spotted. Within the limitation of this study, open CAD-CAM systems used in this study can be assembled properly to fabricate zirconia crown.

• Analytical Science and Technology
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• v.21 no.4
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• pp.316-325
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• 2008

An inductively coupled plasma mass spectrometry (ICP-MS) instrument equipped with flow injection-hydride generation system was used for the determination of trace arsenic in seawater sample. The accuracy in this method was verified by the analysis of certified reference materials (CRM) of seawater (CASS-4, NASS-5). The analytical results agreed with certified value within the range of uncertainty. The expanded uncertainties for CASS-4 and NASS-5 in this experiment were ranged from 6.2% to 6.8% obtained from repeated analyses of the CRMs (n=5). The detection limit of $As^+$ (m/z=74.9216) in this method was confirmed about 0.01 ug/kg. Linearity obtained from calibration curve of arsenic was excellent ($R^2=1$). The detection at $As^+$ (m/z=74.9216) and $AsO^+$ (m/z=90.9165) by using oxygen reaction gas in DRC mode was compared. Sensitivity at $AsO^+$ (m/z=90.9165) was decreased about 25-fold, but the analytical results are the same that at $As^+$ (m/z=74.9216).

• The Journal of the Acoustical Society of Korea
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• v.43 no.3
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• pp.351-360
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• 2024

With the increasing use of drone technology, the Unmanned Aerial Vehicle (UAV) is now being utilized in various fields. However, this increased use of drones has resulted in various issues. Due to its small size, the drone is difficult to detect with radar or optical equipment, so acoustical tracking methods have been recently applied. In this paper, a method of localization of multiple drones using the acoustic characteristics of the quadcopter drone is suggested. Because the acoustic characteristics induced by each rotor are differentiated depending on the type of drone and its movement state, the sound source of the drone can be reconstructed by spatially clustering the results of the estimated positions of the blade passing frequency and its harmonic sound source. The reconstructed sound sources are utilized to finally determine the location of multiple-drone sound sources by applying the source localization algorithm. An experiment is conducted to analyze the acoustic characteristics of the test quadcopter drones, and the simulations for three different types of drones are conducted to localize the multiple drones based on the measured acoustic signals. The test result shows that the location of multiple drones can be estimated by utilizing the acoustic characteristics of the drone. Also, one can see that the clarity of the separated drone sound source and the source localization algorithm affect the accuracy of the localization for multiple-drone sound sources.

• Journal of the Korean earth science society
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• v.37 no.1
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• pp.29-39
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• 2016

In this study, we estimated solar radiation by multiple regression analysis using sunshine duration and precipitation data, which are highly correlated to solar radiation. We found the regression equation using data obtained from GROM (Gangwon Regional Office of Metrology, station 105, 1980-2007) located in Gangneung, South Korea and validated the equation by applying data obtained from new GROM (newly relocated, station 104, 2009-2014) and data obtained from GWNU (Gangneung-Wonju National University, 2013-2014) located between stations 104 and 105. By using sunshine duration data alone, the estimation using data from station 104 resulted in a correlation coefficient of 0.96 and a standard error of $1.16MJm^{-2}$, which was similar to the previous results; the estimation using data from GWNU yielded better results with a correlation coefficient of 0.99 and a standard error of $0.57MJm^{-2}$. By using sunshine duration and precipitation data, the estimation (using data from station 104) yielded a correlation coefficient of 0.96 and a standard error of $0.99MJm^{-2}$, resulting in a lower standard error compared to what was obtained using sunshine duration data alone. The maximum solar radiation bias increased from -26.6% (March 2013) to -31.0% (February 2011) when both sunshine duration and precipitation data were incorporated into the estimation rather than when sunshine duration data alone was incorporated. This was attributed to the concentrated precipitation found during May and July-September, which resulted in negative coefficients of the estimating equation in other months. Therefore, the monthly average solar radiation should be estimated carefully when employing the monthly average precipitation for those places where precipitation is concentrated during summer, such as the Korean peninsula.

• Progress in Medical Physics
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• v.24 no.2
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• pp.99-107
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• 2013

The surgical resection was occurred mainly in liver metastasis before the development of radiation therapy techniques. Recently, Radiation therapy is increased gradually due to the development of radiation dose delivery techniques. 18F-FDG PET image showed better sensitivity and specificity in liver metastasis detection. This image modality is important in the radiation treatment with planning CT for tumor delineation. In this study, we applied automatic image segmentation methods on PET image of liver metastasis and examined the impact of image factors on these methods. We selected the patients who were received the radiation therapy and 18F-FDG PET/CT in Korea Cancer Center Hospital from 2009 to 2012. Then, three kinds of image segmentation methods had been applied; The relative threshold method, the Gradient method and the region growing method. Based on these results, we performed statistical analysis in two directions. 1. comparison of GTV and image segmentation results. 2. performance of regression analysis for relation between image factor affecting image segmentation techniques. The mean volume of GTV was $60.9{\pm}65.9$ cc and the $GTV_{40%}$ was $22.43{\pm}35.27$ cc, and the $GTV_{50%}$ was $10.11{\pm}17.92$ cc, the $GTV_{RG}$ was $32.89{\pm}36.8$4 cc, the $GTV_{GD}$ was $30.34{\pm}35.77$ cc, respectively. The most similar segmentation method with the GTV result was the region growing method. For the quantitative analysis of the image factors which influenced on the region growing method, we used the standardized coefficient ${\beta}$, factors affecting the region growing method show GTV, $TumorSUV_{MAX/MIN}$, $SUV_{max}$, TBR in order. The result of the region growing (automatic segmentation) method showed the most similar result with the CT based GTV and the region growing method was affected by image factors. If we define the tumor volume by the auto image segmentation method which reflect the PET image parameters, more accurate and consistent tumor contouring can be done. And we can irradiate the optimized radiation dose to the cancer, ultimately.