• Journal of Korean Society of Environmental Engineers
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• v.35 no.10
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• pp.717-723
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• 2013

The Korea Ministry of Environment prepares some paticulate matter eliminate measures for national health protection, as the Paticulate Matter ($PM_{2.5}$) exceeds the standard at more than half of the monitoring posts installed in the nation's big cities. At the center of JeonJu, when measuring the ultrafine particles of inner car at the different driving conditions, at the condition of the Actuator of inner recirculation mode and the Blower of 2-speed, the reduction speed of the ultrafine particles is most fast and the concentration stays low. When the windows are opened during driving, outer pollutants enter the car and also inner paticulate matter flies in all direction, and the increase of passengers causes the scattering of the ultrafine paticles. As the filter for air cleaning, the using of polypropylene non-woven fabric (used commonly now) is most excellent, but for the removal of volatile organic substance as well as the paticulate matter, it is thought that the using of activated carbon fiber filter, carbon adsorbent, is even more excellent.

• Korean Journal of Remote Sensing
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• v.24 no.6
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• pp.559-569
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• 2008

The Geostationary Ocean Color Imager (GOCI) on board the Communication Ocean Meteorological Satellite (COMS), the first geostationary ocean color sensor, requires accurate atmospheric correction since its eight bands are also affected by atmospheric constituents such as gases, molecules and atmospheric aerosols. Unlike gases and molecules in the atmosphere, aerosols can interact with sunlight by complex scattering and absorption properties. For the purpose of qualified ocean remote sensing, understanding of aerosol-radiation interactions is needed. In this study, we show micro-physical and optical properties of aerosols using the Optical Property of Aerosol and Cloud (OPAC) aerosol models. Aerosol optical properties, then, were used to analysis the relationship between theoretical satellite measured radiation from radiative transfer calculations and aerosol optical thickness (AOT) under various environments (aerosol type and loadings). It is found that the choice of aerosol type makes little different in AOT retrieval for AOT<0.2. Otherwise AOT differences between true and retrieved increase as AOT increases. Furthermore, the differences between the AOT and angstrom exponent from standard algorithms and this study, and the comparison with ground based sunphotometer observations are investigated. Over the northeast Asian region, these comparisons suggest that spatially averaged mean AOT retrieved from this study is much better than from standard ocean color algorithm. Finally, these results will be useful for aerosol retrieval or atmospheric correction of COMS/GOCI data processing.

• Journal of the Korean Society of Radiology
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• v.15 no.2
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• pp.173-179
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• 2021

Scattered x-ray generated by digital radiography systems also have the advantage of increasing signals, but ultimately detectability is reduced by decreasing resolution and increasing noise of x-ray images transmitted objects. An indirect method of measuring scattered x-ray in a modulation-transfer function (MTF) for evaluating resolution in a spatial-frequency domain can be considered as a drop in the MTF value corresponding to zero-frequency. In this study, polymethyl methacrylate (PMMA) was used as a patient tissue equivalent, and MTFs were obtained for various thicknesses to quantify the effect of scattered x-ray on resolution. X-ray image signals were observed to decrease by 35 ~ 83% with PMMA thickness increasing, which is determined by the absorption or scattering of x-rays in PMMA, resulting in reduced MTF and increased scatter fraction. The method to compensate for MTF degradation by PMMA resulted in the MTF inflation without considering the optical spreading generated by the indirect-conversion type detector. Data fitting or zero-padding are needed to compensate for MTF more reasonably on edge-spread function or line-spread function.

• Applied Chemistry for Engineering
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• v.33 no.1
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• pp.50-57
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• 2022

Ti-In-Zn-O (TIZO)/Ag/TIZO multilayer transparent electrodes were prepared on glass substrates at room temperature using RF/DC magnetron sputtering. Obtained multilayer structure comprising TIZO/Ag/TIZO (10 nm/10 nm/40 nm) with the total thickness of 60 nm showed a transmittance of 86.5% at 650 nm and a sheet resistance of 8.1 Ω/□. The multilayer films were expected to be applicable for use in energy-saving smart window based on polymer-dispersed liquid crystal (PDLC) because of their transmittance properties to effectively block infrared rays (heat rays). We investigated the effects of the content ratio of prepolymer, the thickness of the PDLC coating layer, and the ultraviolet (UV) light intensity on electro-optical properties, and the surface morphology of polyester acrylate-based PDLC systems using new TIZO/Ag/TIZO transparent conducting electrodes. A PDLC cell with a thickness of 15 ㎛ PDLC layer photocured at an UV intensity of 1.5 mW/cm² exhibited good driving voltage, favorable on-state transmittance, and excellent off-haze. The LC droplets formed on the surface of the polymer matrix of the PDLC composite had a size range of 1 to 3 ㎛ capable of efficiently scattering incident light. Also, the PDLC-based smart window manufactured using TIZO/Ag/TIZO multi-layered transparent electrodes in this study exhibited a light brown, which will have an advantage in terms of aesthetics.

• Korean Journal of Heritage: History & Science
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• v.54 no.3
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• pp.24-51
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• 2021

Since June 2006, there have been active efforts to systematize the permission system including the amendment of [Cultural Heritage Protection Act]. Cultural Heritage Administration prepared standards on reviewing each type of cultural heritages(CH) in 2015, promoted a project on the modification of permission standards and showed remarkable performances in quantitative aspects. But as there has been little change for the cases applied for permission, additional studies on policy are required to improve the management efficiency and reduce the citizens'inconvenience. In response, this study aims to identify the actual management status on the current state alteration permission system, and establish practically utilizable reference materials at permission review. While historic sites(HS) constitute a relatively small proportion in state-designated CHs, they are subject to the designation of permission standards. Also, with their location in the downtown area, the application rate is high (51.4%) and the results are commonly utilizable to other types of CH. We constructed a DB based on the minutes of Cultural Heritage Committee(CHC) on HS and categorized similar features in permission handling results. The result of the analysis is as follows. Out of a total of 5,243 cases for permission applied for HS, 1,734 cases of cultural heritage areas(CHA) and 3,509 cases of historic and cultural environment preservation areas(HCEPA) have been applied. CHA has a great proportion of the applications for events and festivals, which are highly related to CHs or representing the local area. There is a high permission rate on applications for the purpose of public service by local governments. Meanwhile, HCEPA has a high proportion of applying for the installation and extension of buildings and facilities at the private level. Thus, negative decisions were made for tall buildings, massed facilities, or suspected scattering of similar acts. Our actual condition analysis has identified a total of 78 types of harmful acts which may influence the preservation of CHs. 31 types in CHA and 37 types in HCEPA are categorized. Especially, 10 common types of permission have been confirmed in both sectors. As a result, it is expected to secure consistency in the permission administration, enhance the management efficiency and improve the public's satisfaction over the regulatory administration by providing practically utilizable reference materials for altering the current state of CH and for decision making on the part of CHC.

• The Korean Journal of Nuclear Medicine Technology
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• v.19 no.2
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• pp.93-101
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• 2015

Purpose In SPECT image, scatter count is the cause of quantitative count error and image quality degradation. Thus, a wide range of scatter correction(SC) methods have been studied and this study is to evaluate the accuracy of CT based SC(CTSC) used in SPECT/CT as the comparison with existing energy window based SC(EWSC). Materials and Methods SPECT/CT images were obtained after filling air in order to acquire a reference image without the influence of scatter count inside the Triple line insert phantom setting hot rod(74.0 MBq) in the middle and each SPECT/CT image was obtained each separately after filling water instead of air in order to derive the influence of scatter count under the same conditions. In both conditions, Astonish(iterative : 4 subset : 16) reconstruction method and CT attenuation correction were commonly applied and three types of SC methods such as non-scatter correction(NSC), EWSC, CTSC were used in images filled with image. For EWSC, 9 sub-energy windows were set additionally in addition to main(=peak) energy window(140 keV, 20%) and then, images were acquired at the same time and five types of EWSC including DPW(dual photo-peak window)10%, DEW(dual energy window)20%, TEW(triple energy window)10%, TEW5.0%, TEW2.5% were used. Under the condition without fluctuations in primary count, total count was measured by drawing volume of interest (VOI) in the images of the two conditions and then, the ratio of scatter count of total counts was calculated as percent scatter fraction(%SF) and the count error with image filled with water was evaluated with percent normalized mean-square error(%NMSE) based on the image filled with air. Results Based on the image filled with air, %SF of images filled with water to which each SC method was applied is NSC 37.44, DPW 27.41, DEW 21.84, TEW10% 19.60, TEW5% 17.02, TEW2.5% 14.68, CTSC 5.57 and the most scattering counts were removed in CTSC and %NMSE is NSC 35.80, DPW 14.28, DEW 7.81, TEW10% 5.94, TEW5% 4.21, TEW2.5% 2.96, CTSC 0.35 and the error in CTSC was found to be the lowest. Conclusion In SPECT/CT images, the application of each scatter correction method used in the experiment could improve the quantitative count error caused by the influence of scatter count. In particular, CTSC showed the lowest %NMSE(=0.35) compared to existing EWSC methods, enabling relatively accurate scatter correction.

• Economic and Environmental Geology
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• v.52 no.2
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• pp.129-139
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• 2019

This study investigates the spectral response of red lettuce (Lactuca sativa var crispa L.) to Zn concentration. The control group and the experimental groups treated with 1 mM(ZnT1), 5 mM(ZnT2), 10 mM(ZnT3), 50 mM(ZnT4), and 100 mM(ZnT5) were prepared for a pot experiment. Then, Zn concentration and spectral reflectance were measured for the different levels of Zn concentration in red lettuce. The Zn concentration of the control group had the range of 134-181 mg/kg, which was within the normal range of Zn concentration in uncontaminated crops. However, Zn concentration in the experimental group gradually increased with an increase in concentration of Zn injection. The spectral reflectance of red lettuce showed high peak in the red band due to anthocyanin, high reflectance in the infrared band due to the scattering effect of the cell structure, and absorption features associated with water. As Zn concentration in red lettuce leaves increased, the reflectance increased in the green and red bands and the reflectance decreased in the infrared band. The correlation analysis between Zn concentration and spectral reflectance showed that the reflectance of 700-1300 nm had a significant negative correlation with Zn concentration. The spectral band is a wavelength region closely related to the cell structure in the leaf, indicating possible cell destruction of leaf structure due to increased Zn concentration. In particular, 700-800 nm reflectance of the infrared band showed the strongest correlation with the Zn concentration. This study could be used to investigate the heavy metal contamination in soil around mining and agriculture area by spectroscopically recognizing heavy metal pollution of plant.

• Journal of Korean Society of Forest Science
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• v.112 no.3
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• pp.352-362
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• 2023

Harvest time is one of the most important determining factors of seed quality, especially for species that produce seeds over irregular and long-term periods, such as Larix kaempferi. A cone collection plan must be established to increase seed production efficiency and stable mass production. We investigated seed qualities such as seed efficiency, germination rate, and T₅₀ (germination speed), with 7 or 8 cone collection times at a clonal seed orchard of L. kaempferi in Chungju between 2021 and 2022. A multivariate analysis was then performed for the collected data. In early August, decreases in the moisture contents and browning of cones were observed. These were followed by a decrease in germination rate, with a peak at the end of September, but no clear trend was observed. The later the cones were harvested, the better the seed vigor (T₅₀). However, the seed yield and efficiency decreased owing to increases in seed scattering and the number of insect-damaged seeds. As a result, the optimal time of seed harvest for the seed orchard was in early August. To produce uniform seedlings, insect damage must be reduced through timely control and harvest cones in early September. This shows that the degree of browning and moisture content of cones can be used as indicators of the timing of cone collection in L. kaempferi seed orchards.

• Radiation Oncology Journal
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• v.20 no.3
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• pp.283-293
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• 2002

Purpose : A PC based brachytherapy planning system was developed to display dose distributions on simulation images by 2D isodose curve including the dose profiles, dose-volume histogram and 30 dose distributions. Materials and Methods : Brachytherapy dose planning software was developed especially for the Ir-192 source, which had been developed by KAERI as a substitute for the Co-60 source. The dose computation was achieved by searching for a pre-computed dose matrix which was tabulated as a function of radial and axial distance from a source. In the computation process, the effects of the tissue scattering correction factor and anisotropic dose distributions were included. The computed dose distributions were displayed in 2D film image including the profile dose, 3D isodose curves with wire frame forms and dosevolume histogram. Results : The brachytherapy dose plan was initiated by obtaining source positions on the principal plane of the source axis. The dose distributions in tissue were computed on a $200\times200\;(mm^2)$ plane on which the source axis was located at the center of the plane. The point doses along the longitudinal axis of the source were $4.5\~9.0\%$ smaller than those on the radial axis of the plane, due to the anisotropy created by the cylindrical shape of the source. When compared to manual calculation, the point doses showed $1\~5\%$ discrepancies from the benchmarking plan. The 2D dose distributions of different planes were matched to the same administered isodose level in order to analyze the shape of the optimized dose level. The accumulated dose-volume histogram, displayed as a function of the percentage volume of administered minimum dose level, was used to guide the volume analysis. Conclusion : This study evaluated the developed computerized dose planning system of brachytherapy. The dose distribution was displayed on the coronal, sagittal and axial planes with the dose histogram. The accumulated DVH and 3D dose distributions provided by the developed system may be useful tools for dose analysis in comparison with orthogonal dose planning.

• Journal of the Korean Society of Radiology
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• v.15 no.2
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• pp.109-115
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• 2021

This study is a study on the difference in dose according to the presence or absence of gonadal shielding of scattered rays generated during chest computed tomography examination, and the scattered dose of the examination site was measured by placing the RadEye G-10 device in the center of the phantom. When the gonads are not shielded, the scattering lines of the whole, both sides, posterior and gonads are measured and Xenolite nolead Apron (0.35 mm PB), Xenolite nolead Apron (front 0.35 mm PB Mix back 0.25 mm PB, Skirt overlap), Half Apron After shielding with (0.5 mm PB), each scattered dose was measured. During chest computed tomography, the scattered dose of the test site was measured at 272 μSv, and when not shielded with Apron, the average total was 43 μSv, left 81 μSv, right part 82 μSv, posterior part 38.8 μSv, and Gonad part 16 μSv. Became. Xenolite nolead Apron shielded only the upper part and measured all 11.2 μSv, left part 43.1 μSv, right part 45.3 μSv, posterior part 12 μSv and Gonad part 5.2 μSv. Xenolite nolead Apron (Skirt overlap) covered the Pelvis area 360° and the dose was measured to be 5.6 μSv in the whole, 22.4 μSv in the left, 15.7 μSv in the right side, 6 μSv in the posterior part, and 3.2 μSv in the Gonad part. Xenolite nolead Apron (Skirt overlap) covered the Pelvis area 360° and the dose was measured to be 5.6 μSv in the whole, 22.4 μSv in the left, 15.7 μSv in the right side, 6 μSv in the posterior part, and 3.2 μSv in the Gonad part. When measuring only the upper part with Half Apron, the total measurement was 10.7 μSv, the left part 42.6 μSv, the right part 40.6 μSv, the posterior part 11.3 μSv, and the Gonad part 4.7 μSv. The method of 360° shielding of the pelvic area showed a dose reduction of more than 80%, and a dose reduction effect of more than 70% was shown when all shielding was performed. In all computerized tomography examinations, research to reduce the exposure dose and various shielding devices were used. It is believed that continuous research on the technique is needed.