• Korean Journal of Remote Sensing
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• v.15 no.4
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• pp.307-319
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• 1999

The aim of this study is to assess the OSMI (Ocean Scanning Multi-spectral Imager), whose central bands are 443nm, 490nm, 510nm, 555nm, 670nm, and 865nm, for agricultural applications. Radiance measurements, used to determine per cent reflectance of canopies and soils, were acquired with spectro-radiometers (Li-1800;330∼1,100nm, GER-SFOV;350∼2,500nm, and MSR-7000; 300∼2,500nm) in situ for crops and indoors for soils. OSMI equivalent bands and their ratio values were prepared(20nm interval for bands 1∼5; 40nm interval for band 6) by averaging spectral reflectance values to the real OSMI bands and analyzed as to crop growth parameters, leaf area index (LAI), total dry matter, and growth index in crops and physiochemical properties in soils. Spectral variations for each growth stage in rice and for crop discrimination in upland crops were significant statistically. In soils, clay and water content, CEC (Cation Exchange Capacity), free iron oxide, and some cation content were correlated with the OSMI equivalent bands. The result of this study shows OSMI wave bands would be promising for agricultural application in terms of spectral information and resolution.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.38 no.5
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• pp.435-441
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• 2020

Sentinel-2A satellite imagery provides VNIR (Visible Near InfraRed) and SWIR (ShortWave InfraRed) wavelength bands, and it is known to be effective for land cover classification, cloud detection, and environmental monitoring. Greenhouse is one of the middle classification classes for land cover map provided by the Ministry of Environment of the Republic of Korea. Since greenhouse is a class that has a lot of changes due to natural disasters such as storm and flood damage, there is a limit to updating the greenhouse at a rapid cycle in the land cover map. In the present study, we utilized Sentinel-2A satellite images that provide both VNIR and SWIR bands for the detection of greenhouse. To utilize Sentinel-2A satellite images for the detection of greenhouse, we produced high-resolution SWIR bands applying to the fusion technique performed in two stages and carried out the detection of greenhouse using SVM (Support Vector Machine) supervised classification technique. In order to analyze the applicability of SWIR bands to greenhouse detection, comparative evaluation was performed using the detection results applying only VNIR bands. As a results of quantitative and qualitative evaluation, the result of detection by additionally applying SWIR bands was found to be superior to the result of applying only VNIR bands.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.11a
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• pp.279-282
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• 2003

For the millimeter-wave dielectrics, Forsterite-based ceramics were produced. Pure forsterite ceramics($Mg_2SiO_4$) shows porous micro-structure and very low Q*f values, which is not suitable for the dielectrics for the millimeter-wave band. Several sintering aids including $Al_2O_3$, $Li_2CO_3$, $Li_2SiO_4$, were added to the forsterite ceramics in order to produce dense low-loss dielectrics. Among these additives, $Li_2CO_3$ is the most effective sintering aids. Several sub-components including NiO, ZnO, $SnO_2$, $TiO_2$, were added to enhance the microwave dielectric properties. $TiO_2$ is the most effective additive to enhance the dielectric properties at microwave bands. The simultaneous addition of $TiO_2$ and $Li_2CO_3$ increases Q*f value over 170,000, which can be used as dielectrics in millimeter-wave bands.

• Korean Journal of Remote Sensing
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• v.38 no.5_1
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• pp.523-533
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• 2022

This paper presents a two-stage spatio-spectral fusion method (2SSFM) based on area-to-point regression kriging (ATPRK) to enhance spatial and spectral resolutions using multi-sensor satellite images with complementary spatial and spectral resolutions. 2SSFM combines ATPRK and random forest regression to predict spectral bands at high spatial resolution from multi-sensor satellite images. In the first stage, ATPRK-based spatial down scaling is performed to reduce the differences in spatial resolution between multi-sensor satellite images. In the second stage, regression modeling using random forest is then applied to quantify the relationship of spectral bands between multi-sensor satellite images. The prediction performance of 2SSFM was evaluated through a case study of the generation of red-edge and short-wave infrared bands. The red-edge and short-wave infrared bands of PlanetScope images were predicted from Sentinel-2 images using 2SSFM. From the case study, 2SSFM could generate red-edge and short-wave infrared bands with improved spatial resolution and similar spectral patterns to the actual spectral bands, which confirms the feasibility of 2SSFM for the generation of spectral bands not provided in high spatial resolution satellite images. Thus, 2SSFM can be applied to generate various spectral indices using the predicted spectral bands that are actually unavailable but effective for environmental monitoring.

• Journal of the Korean Institute of Navigation
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• v.15 no.4
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• pp.13-25
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• 1991

Recently, according to the development of electromagnetic wave technique, more frequent and powerfull wave radiation becomes inevitable and so electromagnetic environments has become worse accordingly. Electromagnetic wave absorber is known the most effective preventive remedy to cope with the EMI/EMC problem. To realize broad-band electromagnetic wave absorber, triple layered structure where an air layer is interposed between a sintered ferrite layer and a ruber ferrite layer was adopted. Computer simulation for optimum design and evaluation of absorption characteristics has been made. The results shows that designed broad-band electromagnetic wave absorber can be useful for EMI/EMC problem, especially reducing TV ghosts in both VHF and UHF bands by additionally an air layer and a thin rubber ferrite layer on the surface of conventional ferrite, without replacing it.

• Proceedings of the Materials Research Society of Korea Conference
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• 2009.11a
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• pp.14-14
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• 2009

High frequency electromagnetic(EM) waves are increasingly being applied in industries because of saturationat lower frequency bands as a result of huge demand. However, electromagneticinterference (EMI) has become a serious problem, and as a result, highfrequency EM absorbers are now being extensively studied. Also, recentdevelopments in absorber technology have focused on producing absorbers thatare thin, flexible, and strong. Hence, one-dimension ferrous nano-materials area potential research field, because of their interesting electronic andmagnetic properties. Commercially, EM wave absorbing products are made ofcomposites, which blend the insulating polymer with magnetic fillers. Inparticular, the shape of the magnetic fillers, such flaky, acicular, or fibrousmagnetic metal particles, rather than spherical, is essential for synthesizingthin and lightweight EM wave absorbers with higher permeability. High aspectratio materials exhibit a higher permeability value and therefore betterabsorption of the EM wave, because of electromagnetic anisotropy. Nanowires areusually fabricated by drawing, template synthesis, phase separation, selfassembly, and electrospinning with a thermal treatment and reduction process.Producing nanowires by the electrospinning method involves a conventionalsol-gel process that is simple, unique, and cost-effective. In thispresentation, Magnetic nanowire and dielectric materials coated magneticnanowire with a high aspect ratio were successfully synthesized by theelectrospinning process with heat treatment and reduction. In addition toestimating the EM wave absorption ability of the synthesized magnetic anddielectric materials coated magnetic nanowire with a network analyzer, weinvestigated the possibility of using these nanowires as high-frequency EM waveabsorbers. Furthermore, a wide variety of topics will be discussed such as thetransparent conducting nanowire and semiconducting nanowire/tube with theelectrospinning process.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.9
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• pp.783-790
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• 2016

Since scarcity of spectrum in future mobile networks, millimeter wave frequencies from 30 GHz to 300 GHz have been proposed to be used in an important part of 5G mobile communication backhaul links to provide several giga bits services. In ITU-R has been invited to conduct and complete in time for WRC-19 the appropriate studies to determine the spectrum needs for the terrestrial component of IMT in the frequency range between 24.25 GHz and 86 GHz. Also, small cells such as a femtocell, and heterogeneous networks have been deployed through world in order to enhance the communication capacity. At this stage, it is important to develop millimeter wave frequencies to provide 5G mobile broadband services, and thus this paper proposes the effective usage of these frequencies by summarizing the FCC allocation of millimeter waves, their propagation characteristics, the required minimum path length, and the interference effect.

• Korean Journal of Materials Research
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• v.29 no.6
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• pp.363-370
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• 2019

The recent development of information and communication technologies brings new changes to automobile traffic systems. The most typical example is the advancement of dedicated short range communication(DSRC). DSRC mainly consists of an intelligent transportation system(ITS), an electronic toll collection system(ETCS) and an advanced traveler information system(ATIS). These wireless communications often cause unnecessary electromagnetic waves, and these electromagnetic waves, in turn, cause frequent system malfunction. To solve this problem, an absorber of electromagnetic waves is suggested. In this research, various materials, such as powdered metal and iron oxides, are used to test the possibility for an effective absorption of the unnecessary electromagnetic waves. The various metal powders are made into a thin sheet form by compositing through processing. The electromagnetic characteristics(complex permittivity, complex permeability) of the fabricated sheet are measured. As a result, we achieve -6.5 dB at 940 MHz(77.6 % absorption rate) with a 1.0 mm-thickness electromagnet wave absorber, and -9.5 dB at 940 MHz(88.8 % absorption rate) with a 2.0 mm-thickness absorber.

• Clinics in Shoulder and Elbow
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• v.19 no.1
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• pp.20-24
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• 2016

Background: Extracorporeal shock wave therapy (ESWT) is one of the treatment options used for patients with myofascial pain syndrome (MPS), although its effectiveness is controversial. The purpose of this study was to evaluate the effectiveness of ESWT in the treatment of MPS in terms of pain relief and functional improvements. Methods: We assessed 93 patients with MPS who underwent ESWT from March 2009 to July 2014. After exclusion of 25 patients with shoulder diseases, 68 patients were enrolled in the study. The mean follow-up period was 7.5 months (${\pm}4.2weeks$), and the average duration of symptoms was 5 months (range, 2-16 months). ESWT was applied to intramuscular taut bands and referred pain areas once a week for 3 weeks. Visual analog scale (VAS) pain scores and American Shoulder and Elbow Surgeons (ASES) scores were obtained at an initial assessment and at the 6-week, 3-month, and 6-month follow-up assessments. Results: VAS pain scores and ASES scores improved significantly after 3 sessions of ESWT (p<0.05). Both scores were improved, although not significantly, after 6 weeks (p>0.05). Conclusions: ESWT is an effective treatment option for patients with MPS.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.12 no.3
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• pp.224-238
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• 1987

In the proposed spectrum analyzer, open-loop VCO is replaced with PLL synthesizer incorporating digital frequency synthesizer using modulofunction for measuring precise frequencys. Three different frequency bands and channel spacings are realized by single loop synthesizer through the effective design of the system. The newly designed system with square detection has a good linearity of input range from 10mV to 8.5V, as a result the input sensitivity has been improved up to 500uV. The storage function enables us to analyze not only periodic but also nonperiodic wave-form and zoom-in function expands frequency resolution eight times for the dense spectra.