• Korean Journal of Agricultural and Forest Meteorology
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• v.23 no.4
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• pp.316-328
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• 2021

In this study, the leaf Na content prediction model for spring potato was established using 400-1000 nm hyperspectral sensor to develop the multispectral sensor for the salinity monitoring in reclaimed land. The irrigation conditions were standard, drought, and salinity (2, 4, 8 dS/m), and the irrigation amount was calculated based on the amount of evaporation. The leaves' Na contents were measured 1st and 2nd weeks after starting irrigation in the vegetative, tuber formative, and tuber growing periods, respectively. The reflectance of the leaves was converted from 5 nm to 10 nm, 25 nm, and 50 nm of FWHM (full width at half maximum) based on the 10 nm wavelength intervals. Using the variance importance in projections of partial least square regression(PLSR-VIP), ten band ratios were selected as the variables to predict salinity damage levels with Na content of spring potato leaves. The MLR(Multiple linear regression) models were estimated by removing the band ratios one by one in the order of the lowest weight among the ten band ratios. The performance of models was compared by not only R2, MAPE but also the number of band ratios, optimal FWHM to develop the compact multispectral sensor. It was an advantage to use 25 nm of FWHM to predict the amount of Na in leaves for spring potatoes during the 1st and 2nd weeks vegetative and tuber formative periods and 2 weeks tuber growing periods. The selected bandpass filters were 15 bands and mainly in red and red-edge regions such as 430/440, 490/500, 500/510, 550/560, 570/580, 590/600, 640/650, 650/660, 670/680, 680/690, 690/700, 700/710, 710/720, 720/730, 730/740 nm.

• Economic and Environmental Geology
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• v.51 no.4
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• pp.345-358
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• 2018

In this study, we have performed electron probe micro analyzer (EPMA), X-ray differaction (XRD), inductively coupled plasma spectroscopy (ICP), Fourier transform Raman spectroscopy (FT-Raman), far-infrared (FIR), nuclear magnetic resonance (NMR), and pH-DO Analyses for characterizing medicinal mineralogy aspect of the black tourmaline (Shantung, china), black and pink tourmaline (Minas Geraris, Brazil), black touemaline (Daeyu mine, Korea). In addition, heating effects of the tourmaline sauna as well as the effects of tourmaline powder-added soap on skin troubles have been investigated. It has been revealed that chemical composition of the tourmaline is either high in Fe-, Al-, B-rich types. Ratio of the K-Ca, Na-K, and Fe-B reflects the component change property of solid solution. $CaO/CaO+Na_2O$ and MgO/FeO+MgO ratio show high positive correlation. When tourmaline reacts with distilled water, extended reaction time DO values approximately decrease and it stabilizes at DO = 10. Otherwise, pH values increase until 6 hours and it stabilizes at pH = 8 after 24 hours. Distilled water changes to alkaline when it reacts with tourmaline powder and particles. Tourmaline showed lower absorption spectrum strength and transmittance at short wave, where absorption spectrum wavelength and strength were determined by the content of the composition elements and characteristics of crystallography. Increase of the Fe content has been confirmed to be the cause for the reduction of irradiation. For the chemical composition and spectral property of the tourmaline particle samples, it has been found that Si and Fe contents show positive correlation with Far-Infrared irradiation, while Al and Mg contents show negative correlation. For tourmaline powder, it has been confirmed that $^{17}O-NMR$ FWHM (full width at half maximum) decreases when reacts with distilled water. Tourmaline sauna (approximately $100^{\circ}C$) was found to increase $0.5-1.5^{\circ}C$ of body temperature, average of 12 heartbeat, and 10mg Hg of blood pressure. Tourmaline soap had very good aesthetic effect to skin and was confirmed to have above the average improvements to skin troubles (e.g., allergy or atopy).

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2004.04a
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• pp.5-9
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• 2004

In this paper, we studied the OCT(Optical Coherence Tomography) system which it has been extensively studied because of having some advantages such as high resolution cross-sectional images, low cost, and small size configuration. A basic principle of OCT system is Michelson interferometer. The characteristics of light source determine the resolution and the transmission depth. As a results, the light source have a commercial SLD with a central wavelength of 1,285 nm and FWHM(Full Width at Half Maximum) of 35.3 nm. The optical delay line part is necessary to equal of the optical path length with scattered light or reflected light from sample. In order to equal the optical path length, the stage which is attached to reference mirror is moved linearly by step motor And the interferometer is configured with the Michelson interferometer using single mod fiber, the scanner can be focused of the sample by using the reference arm. Also, the 2-dimensional cross-sectional images were measured with scanning the transverse direction of the sample by using step motor. After detecting the internal signal of lateral direction at a paint of sample, scanner is moved to obtain the cross-sectional image of 2-demensional by using step motor. Photodiode has been used which has high detection sensitivity, excellent noise characteristic, and dynamic range from 800 nm to 1,700 nm. It is detected mixed small signal between noise and interference signal with high frequency After filtering and amplifying this signal, only envelope curve of interference signal is detected. And then, cross-sectional image is shown through converting this signal into digitalized signal using A／D converter. The resolution of the OCT system is about 30$\mu\textrm{m}$ which corresponds to the theoretical resolution. Also, the cross-sectional image of ping-pong ball is measured. The OCT system is configured with Michelson interferometer which has a low contrast because of reducing the power of feedback interference light. Such a problem is overcomed by using the improved inteferometer. Also, in order to obtain the cross-sectional image within a short time, it is necessary to reduce the measurement time for improving the optical delay line.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.7
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• pp.667-678
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• 2002

In this paper, a new radiating structure with a multi-layered two-dimensional metallic disk array was proposed for shaping the flat-topped element pattern. It is an infinite periodic planar array structure with metallic disks finitely stacked above the radiating circular waveguide apertures. The theoretical analysis was in detail performed using rigid full-wave analysis, and was based on modal representations for the fields in the partial regions of the array structure and for the currents on the metallic disks. The final system of linear algebraic equations was derived using the orthogonal property of vector wave functions, mode-matching method, boundary conditions and Galerkin's method, and also their unknown modal coefficients needed for calculation of the array characteristics were determined by Gauss elimination method. The application of the algorithm was demonstrated in an array design for shaping the flat-topped element patterns of $\pm$20$^{\circ}$ beam width in Ka-band. The optimal design parameters normalized by a wavelength for general applications are presented, which are obtained through optimization process on the basis of simulation and design experience. A Ka-band experimental breadboard with symmetric nineteen elements was fabricated to compare simulation results with experimental results. The metallic disks array structure stacked above the radiating circular waveguide apertures was realized using ion-beam deposition method on thin polymer films. It was shown that the calculated and measured element patterns of the breadboard were in very close agreement within the beam scanning range. The result analysis for side lobe and grating lobe was done, and also a blindness phenomenon was discussed, which may cause by multi-layered metallic disk structure at the broadside. Input VSWR of the breadboard was less than 1.14, and its gains measured at 29.0 GHz. 29.5 GHz and 30 GHz were 10.2 dB, 10.0 dB and 10.7 dB, respectively. The experimental and simulation results showed that the proposed multi-layered metallic disk array structure could shape the efficient flat-topped element pattern.

• Korean Journal of Soil Science and Fertilizer
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• v.42 no.5
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• pp.399-407
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• 2009

Laser induced breakdown spectroscopy(LIBS) is an simple analysis method for directly quantifying many kinds of soil micro-elements on site using a small size of laser without pre-treatment at any property of materials(solid, liquid and gas). The purpose of this study were to find an optimum condition of the LIBS measurement including wavelengths for quantifying soil elements, to relate spectral properties to the concentration of soil elements using LIBS as a simultaneous un-breakdown quantitative analysis technology, which can be applied for the safety assessment of agricultural products and precision agriculture, and to compare the results with a standardized chemical analysis method. Soil samples classified as fine-silty, mixed, thermic Typic Hapludalf(Memphis series) from grassland and uplands in Tennessee, USA were collected, crushed, and prepared for further analysis or LIBS measurement. The samples were measured using LIBS ranged from 200 to 600 nm(0.03 nm interval) with a Nd:YAG laser at 532 nm, with a beam energy of 25 mJ per pulse, a pulse width of 5 ns, and a repetition rate of 10 Hz. The optimum wavelength(${\lambda}nm$) of LIBS for estimating soil and plant elements were 308.2 nm for Al, 428.3 nm for Ca, 247.8 nm for T-C, 438.3 nm for Fe, 766.5 nm for K, 85.2 nm for Mg, 330.2 nm for Na, 213.6 nm for P, 180.7 nm for S, 288.2 nm for Si, and 351.9 nm for Ti, respectively. Coefficients of determination($r^2$) of calibration curve using standard reference soil samples for each element from LIBS measurement were ranged from 0.863 to 0.977. In comparison with ICP-AES(Inductively coupled plasma atomic emission spectroscopy) measurement, measurement error in terms of relative standard error were calculated. Silicon dioxide(SiO2) concentration estimated from two methods showed good agreement with -3.5% of relative standard error. The relative standard errors for the other elements were high. It implies that the prediction accuracy is low which might be caused by matrix effect such as particle size and constituent of soils. It is necessary to enhance the measurement and prediction accuracy of LIBS by improving pretreatment process, standard reference soil samples, and measurement method for a reliable quantification method.

• Korean Journal of Heritage: History & Science
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• v.44 no.4
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• pp.142-153
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• 2011

'Silla Monument Stone in Jungseong-ri, Pohang' was discovered in Pohang City, Gyeongsangbuk Province of Korea in 2009. The monument stone with irregular shape has dimensions of maximum height of 105cm, width of 47.6~49.6cm, thickness of 13.8~14.7cm and weight of 115kg. The results of monument stone was found to be granitite. Conservation treatment procedure was carried out in the order of production of Weathering map, cleaning of surface pollutants, consolidation using ethyl silicate. Black pollutant(crust) that covered more than 60% of the surface was analyzed first in order to remove the pollutants on the surface of the monumental stone by cleaning of surface pollutants using laser. The purpose on analysis was not only to verify the pollutants on the stone but also to carry out preliminary cleaning by securing rocks with same pollutant as the monumental stone. As the results of analysis using p-XRF(PMI. INNOV-X, USA) on the site, high level of Mn and Fe were detected, and the analysis of small section that had been fallen off with SEM/EDX for the purpose of quantitative analysis also detected high level of Mn. The Similar contaminants on Stone secured in the manner described above were made into 10 samples ($5cm{\times}5cm$) and was subjected to preliminary cleaning by Nd-YAG Laser(Laser&Physics, Korea). The results of surface observation through portable microscope during cleaning revealed that the power of 460mJ, wavelength of 1064nm and irradiation frequency of 1,800~2,300 per $25cm^2$ were most effective. Evaluation on the preservative treatment was made through confirmation of the extent of removal through color-difference meter measurement and component analysis prior to and following removal of the pollutants. As the result of color-difference meter measurement increase in the brightness was evidenced by the increase in the brightness ($L^*$)value from 33 to 49, and it was possible to ascertain the reduction in the pollutants as the content of Mn was reduced by about 80% from $50,000{\pm}5,000ppm$ to $10,000{\pm}2,000pmm$ from the result of component analysis.