• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.153-153
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• 2022

Large-scale and accurate observations at fine spatial resolution through a means of remote sensing offer an effective tool for capturing rainfall variability over the traditional rain gauges and weather radars. Although satellite rainfall products (SRPs) derived using two major estimation approaches were evaluated worldwide, their practical applications suffered from limitations. In particular, the traditional top-down SRPs (e.g., IMERG), which are based on direct estimation of rain rate from microwave satellite observations, are mainly restricted with their coarse spatial resolution, while applications of the bottom-up approach, which allows backward estimation of rainfall from soil moisture signals, to novel high spatial resolution soil moisture satellite sensors over South Korea are not introduced. Thus, this study aims to evaluate the performances of a state-of-the-art bottom-up SRP (the self-calibrated SM2RAIN model) applied to the C-band SAR Sentinel-1, a statistically downscaled version of the conventional top-down IMERG SRP, and their integration for a targeted high spatial resolution of 0.01° (~ 1-km) over central South Korea, where the differences in climate zones (coastal region vs. mainland region) and vegetation covers (croplands vs. mixed forests) are highlighted. The results indicated that each single SRP can provide plus points in distinct climatic and vegetated conditions, while their drawbacks have existed. Superior performance was obtained by merging these individual SRPs, providing preliminary results on a complementary high spatial resolution SRP over central South Korea. This study results shed light on the further development of integration framework and a complementary high spatial resolution rainfall product from multi-satellite sensors as well as multi-observing systems (integrated gauge-radar-satellite) extending for entire South Korea, toward the demands for urban hydrology and microscale agriculture.

• Journal of the Korean Applied Science and Technology
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• v.39 no.6
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• pp.792-801
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• 2022

This study is a descriptive research study conducted to identify evaluative concerns perfectionism, entrapment and depression in university nursing students, and to identify the factors influencing depression. The subjects of the research were students enrolled in two major departments in G city. Statistics, t-test, ANOVA, Pearson correlation coefficient, and band regression analysis were used for data analysis. Research results indicated that the factors influencing depression to university nursing students were external constraints (β=.414, p<.001) and socially imposed perfectionism (β=.174, p<.001), and these explained 24.9% of the subject's degree of depression. In particular, it was found that external Entrapment had the greatest effect by 22.7%. Therefore, based on the results of this research analysis, it is recommended to develop and manage various extracurricular programs that can reduce the external entrapment and socially imposed perfectionism so that depression can be managed, reduced and prevented depression of university nursing students at an early stage.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.18 no.4
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• pp.1042-1058
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• 2024

Terahertz (THz) communication is becoming a key technology for future 6G wireless networks because of its ultra-wide band. However, the implementation of THz communication systems confronts formidable challenges, notably beam splitting effects and high computational complexity associated with them. Our primary objective is to design a hybrid precoder that minimizes the Euclidean distance from the fully digital precoder. The analog precoding part adopts the delay-phase alternating minimization (DP-AltMin) algorithm, which divides the analog precoder into phase shifters and time delayers. This effectively addresses the beam splitting effects within THz communication by incorporating time delays. The traditional digital precoding solution, however, needs matrix inversion in THz massive multiple-input multiple-output (MIMO) communication systems, resulting in significant computational complexity and complicating the design of the analog precoder. To address this issue, we exploit the characteristics of THz massive MIMO communication systems and construct the digital precoder as a product of scale factors and semi-unitary matrices. We utilize Schatten norm and Hölder's inequality to create semi-unitary matrices after initializing the scale factors depending on the power allocation. Finally, the analog precoder and digital precoder are alternately optimized to obtain the ultimate hybrid precoding scheme. Extensive numerical simulations have demonstrated that our proposed algorithm outperforms existing methods in mitigating the beam splitting issue, improving system performance, and exhibiting lower complexity. Furthermore, our approach exhibits a more favorable alignment with practical application requirements, underlying its practicality and efficiency.

• Advances in nano research
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• v.16 no.1
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• pp.41-52
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• 2024

In this study, rare-earth orthoferrites LnFeO₃ were synthesized using a facile hydrothermal reaction and their visible-light-induced photo-Fenton degradation of organics was optimized through Ln variation (Ln = La, Pr, or Gd). The morphological, structural, and chemical characteristics of as-prepared samples were examined in detail by using different methods, including XRD, SEM, TEM, XPS, etc. On the other side, under visible light illumination, the photo-Fenton-like catalytic activities of LnFeO₃ were assessed in terms of the removal of selected organic models, i.e., pharmaceuticals (ketoprofen and tetracycline) and dyes (rhodamine B and methyl orange). As compared with PrFeO₃ or GdFeO₃, the sample of LaFeO₃ displayed more structural distortion, larger specific surface area, and narrower band gap, resulting in its higher photo-Fenton-like catalytic activity toward the degradation of organics. In organic-containing solution, in which the initial solution pH = 5, catalyst dosage = 1 g/L and H₂O₂ concentration = 10 mM, 98.2% of rhodamine B, 31.1% of methyl orange, 67.7% of ketoprofen, or 96.4% of tetracycline was removed after 90-min exposure to simulated visible light. Our findings revealed that variation of Ln site on rare-earth orthoferrites was an effective strategy for optimizing their organic removal via visible-light-induced photo-Fenton reaction.

• Nuclear Engineering and Technology
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• v.56 no.9
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• pp.3804-3811
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• 2024

The study focuses on creating new boro-silicate glasses doped with SnO₂ for radiation shielding. It examines how substituting Na₂O with SnO₂ affects their structural, optical, and shielding properties. Density increases from 2.406 to 2.488 g/cm³ with rising SnO₂, measured via the Archimedes Method. The examination for the glassy phase was performed using the XRD diffractometer. UV/Vis spectrophotometer analysis reveals reduced refractive index (2.412-1.976) and increased optical absorption-band gap (direct: 3.648-5.662 eV; indirect: 2.994-5.163 eV) with SnO₂ concentrations of 0-9 mol.%). The effectiveness of the radiation shielding was assessed over the 0.059-1.408 MeV gamma-ray energy interval. The analysis demonstrates that when the concentration of SnO₂ increases, the synthesized glasses' linear attenuation coefficient improves. As the SnO₂ content was raised between 0 and 9 mol%, the linear attenuation coefficient rose between 0.489 and 2.892 cm^-1 (at energy of 0.059 MeV) and between 0.126 and 0.128 cm^-1 (at energy of 1.408 MeV), respectively. As the SnO₂ content was raised between 0 and 9 mol%.

• Korean Journal of Soil Science and Fertilizer
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• v.11 no.1
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• pp.25-30
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• 1978

Field experiments were conducted on the cropping system soybean-barley-soybean to investigate the effect of phosphorus and wollastonite application, effective application methods of phosphrus, and their residual effect in a typical Jeju island volcanic ash soil when the fertilizers were applied to the first crop of the three crops sequence. The results are summarized as follows. 1. Response of phosphorus was higher for barley than for soybean. The maximum application rate of phosphate was extimated to be 10-20kg/l0a for cultivation of soybean first crop) and 100kg/l0a for barley (second crop). Barley yield under 100kg/l0a of phosphate was double as compared to the no phosphate plot. 2. With application of 100kg/10a phosphate at the sowing time of soybean, the available phosphate in the soil after harvesting of soybean was increased to 175ppm but decreased to 60 ppm by cultivation of barley (second crop.) On the other hand, the phosphate absorption coefficient was 1,146mg/100g after soybean harvest but increased to 1,764mg/100g after barley harvest. 3. High residual effect was found in the plot to which phosphate applied with compost in the sowing band. 4. Response to wollastonite under heavy application of phosphate was high and residual effect was also great. 5. Response of soybean to wollastonite was higher than that of barley. Application of wollastonite increased the yield of all three crops soybean (first crop) by 30%, barley (second crop) by 12% and soybean (third) by 20%, respectively. Highest yield was obtained from the 1,000kg/10a wollastonite treatment for soybean and 500kg/l0a for barley.

• Korean Journal of Remote Sensing
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• v.35 no.6_4
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• pp.1319-1326
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• 2019

The KARI(Korea Aerospace Research Institute) operates the government satellite information application consultation to cope with ever-increasing demand for satellite images in the public sector, and carries out various support projects including the generation and provision of mosaic images on the Korean Peninsula every year to enhance user convenience and promote the use of satellite images. In particular, the government has wanted to increase the utilization of mosaic images on the Korean Peninsula and seek to classify and update mosaic images so that users can use them in their businesses easily. However, it is necessary to test and verify whether the classification results of the mosaic images can be utilized in the field since the original spectral information is distorted during pan-sharpening and color balancing, and there is a limitation that only R, G, and B bands are provided. Therefore, in this study, the reliability of the classification result of the mosaic image was compared to the result of KOMPSAT-3 image. The study found that the accuracy of the classification result of KOMPSAT-3 image was between 81~86% (overall accuracy is about 85%), while the accuracy of the classification result of mosaic image was between 69~72% (overall accuracy is about 72%). This phenomenon is interpreted not only because of the distortion of the original spectral information through pan-sharpening and mosaic processes, but also because NDVI and NDWI information were extracted from KOMPSAT-3 image rather than from the mosaic image, as only three color bands(R, G, B) were provided. Although it is deemed inadequate to distribute classification results extracted from mosaic images at present, it is believed that it will be necessary to explore ways to minimize the distortion of spectral information when making mosaic images and to develop classification techniques suitable for mosaic images as well as the provision of NIR band information. In addition, it is expected that the utilization of images with limited spectral information could be increased in the future if related research continues, such as the comparative analysis of classification results by geomorphological characteristics and the development of machine learning methods for image classification by objects of interest.

• Korean Journal of Food Science and Technology
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• v.36 no.1
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• pp.32-37
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• 2004

Effects of mushroom powder on physicochemical characteristics of dough and bread-making properties were studied. In mixogram test, addition of 2-10% mushroom powder increased water absorption from 67,0 to 79%. Peak time, peak height, band width, and seven minute height of mushroom-wheat flour composite were similar to those of control. Sedimentation and P.K. values decreased with increasing amount of mushroom powder In amylogram test, no significant difference was observed in gelatinization temperature between control and mushroom powder-added dough. Peak viscosity increased with increasing amount of mushroom powder, Highest loaf volume was attained when 2 and 4% mushroom powders were added, whereas decreased above 6%. Bread weight and L value of crust increased with increasing amount of mushroom powder whereas 'a' value decreased. As the amount of mushroom powder increased, L value of crumb color decreased. No significant difference in springiness and adhesiveness was observed between control and mushroom-wheat composite flour bread whereas chewiness and gumminess, increased with increasing amount of mushroom powder, Hardness generally increased as the amount of mushroom powder increased. Mushroom powder caused bread staling at both storage temperatures ($4^{\circ}C\;and\;25^{\circ}C$). Although sensory value decreased with increasing mushroom powder, use of mushroom powder to replace up to 4% wheat flour is recommended in making bread.

• Journal of Sensor Science and Technology
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• v.12 no.6
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• pp.273-281
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• 2003

A stoichiometric mixture for $CdIn_2Te_4$ single crystal was prepared from horizontal electric furnace. The $CdIn_2Te_4$ single crystal was grown in the three-stage vertical electric furnace by using Bridgeman method. The quality of the grown crystal has been investigated by the x-ray diffraction and the photoluminescence measurements. The (001) growth plane of oriented $CdIn_2Te_4$ single crystal was confirmed from back-reflection Laue patterns. The carrier density and mobility of $CdIn_2Te_4$ single crystal measured with Hall effect by van der Pauw method are $8.61{\times}10^{16}\;cm^{-3}$ and $242\;cm^2/V{\cdot}s$ at 293 K, respectively. The temperature dependence of the energy band gap of the $CdIn_2Te_4$ single crystal obtained from the absorption spectra was well described by the Varshni's relation, $E_g(T)=1.4750\;eV-(7.69{\times}10^{-3}\;eV)T^2/(T+2147)$. After the as-grown $CdIn_2Te_4$ single crystal was annealed in Cd-, In-, and Te-atmospheres, the origin of point defects of $CdIn_2Te_4$ single crystal has been investigated by the photoluminescence(PL) at 10 K. The native defects of $V_{Te}$, $Cd_{int}$, and $V_{Cd}$, $Te_{int}$ obtained by PL measurements were classified as a donors or acceptors type. And we concluded that the heat-treatment in the Cd-atmosphere converted $CdIn_2Te_4$ single crystal to an optical n-type. Also, we confirmed that In in $CdIn_2Te_4$ did not form the native defects because In in $CdIn_2Te_4$ single crystal existed in the form of stable bonds.

• Korean Journal of Food Science and Technology
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• v.27 no.5
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• pp.716-723
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• 1995

The fucoidan purified from Korean brown seaweed, Ecklonia stolonifera was characterized on molecular structure and blood anticoagulant activities. Extraction was conducted at $100^{\circ}C$ with water and repeated twice. The crude fucodian was 151.1g out of 20.0 kg of Ecklonia stolonifera. The Fucoidan-1, which was purified from crude fucoidan using calcium chloride and cetyl pyridium chloride (CPC), was 35.2% against crude fucoidan. Fucoidan-5 was obtained approximately 28.1% from Fucoidan-1 through DEAE-Toyopearl 650 M ion-exchange column chromatography and showed one band by cellulose acetate electrophoresis. The molecular weight of Fucoidan-5 was estimated to be about 21,000∼23,000 dalton by Sephacryl S-300 gel filtration chromatography. Fucoidan-5 consists of 35.7% of fucose and 4.3% of galactose and the molar ratio of fucose and sulfate was about one to one. IR spectrum of Fucoidan-5 showed absorption at $1240\;cm^{-1}\;and\;850\;cm^{-1}$ and specific rotation value, $[\alpha]$, was $[\alpha]$. These results suggests that the sulfate maybe bind at $C_{4}$ carbon on ${\alpha}-L-fucose$. Gas chromatograph of methyl alditol acetate revealed that Fucoidan-5 is a fucose containing sulfated polysaccharide with $({\alpha}l-2)\;or\;({\alpha}l-2)$ glycosidic linkage. Anti-thrombin activity of the Fucoidan-5 was estimated as 1.4 time stronger than heparin. From above results, the purification methods using CPC and ion exchange chromatography is effective tools for obtaining highly purified fucoidan from Gompi, Ecklonia stolonifera.