• 대한원격탐사학회지
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• 제15권4호
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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.

• 한국측량학회지
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• 제38권5호
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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.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 추계학술대회 논문집 Vol.16
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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.

• 대한원격탐사학회지
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• 제38권5_1호
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• pp.523-533
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• 2022

이 논문에서는 상호보완적인 공간 및 분광해상도를 가진 다중센서 위성영상을 이용하여 공간해상도와 분광해상도를 향상시키기 위해 영역-점 회귀 크리깅(area-to-point regression kriging, ATPRK) 기반의 2단계 spatio-spectral fusion method (2SSFM)을 제안하였다. 2SSFM은 ATPRK와 random forest 회귀 모형을 결합하여 다중센서 위성영상에서 높은 공간해상도를 갖는 분광 밴드를 예측한다. 첫 번째 단계에서는 다중센서 위성영상 사이의 공간해상도 차이를 감소시키기 위해 ATPRK 기반 공간 상세화를 수행한다. 두 번째 단계에서는 다중센서 위성영상 사이의 분광 밴드의 관계성을 정량화하기 위해 random forest를 이용한 회귀 모델링을 적용하였다. 2SSFM의 예측 성능은 적색 경계와 단파 적외선 밴드를 생성하는 사례 연구를 통해 평가하였다. 사례 연구에서 2SSFM은 실제 분광 밴드와 유사한 분광패턴을 보이면서 공간해상도가 향상된 적색 경계와 단파 적외선 밴드를 생성할 수 있었으며, 2SSFM가 고해상도 위성영상에서 제공하지 않은 분광 밴드 생성에 유용함을 확인할 수 있었다. 따라서 2SSFM을 통해 실제로 획득 불가능하지만 환경 모니터링에 효과적인 분광 밴드를 예측함으로써 다양한 분광 지수를 생성할 수 있을 것으로 기대된다.

• 한국항해학회지
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• 제15권4호
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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.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2009년도 추계학술발표대회
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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.

• 한국전자파학회논문지
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• 제27권9호
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• pp.783-790
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• 2016

향후 이동통신망에서 주파수 부족이 중요한 문제가 되고 있어 광대역의 주파수를 확보할 수 있는 30 GHz에서 300 GHz 대역의 밀리미터파(mmWave) 통신이 수 기가비트 서비스를 제공하기 위한 5G 백홀(backhaul) 통신망의 중요한 일부로서 제안되고 있다. 이에 WRC-19 의제 1.13에서는 24.25~86 GHz 범위에서의 IMT 용 주파수 결정을 추진하고 있으며, 통신용량을 증가시키기 위해 세계적으로 펨토셀(femtocell)과 같은 소형 셀과 이종망을 구축해 나가는 시점에서 광대역 이동통신서비스 제공을 위한 밀리미터파 주파수 개발이 중요시 되고 있다. 따라서 본 논문에서는 FCC의 밀리미터파 스펙트럼의 분배 현황, 전파특성, 최소 경로길이 기준 및 간섭분석 결과를 정리하여 국내의 5G 백홀 링크를 위한 밀리미터파의 효율적 이용방안을 제시한다.

• 한국재료학회지
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• 제29권6호
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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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• 제19권1호
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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.

• 한국통신학회논문지
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• 제12권3호
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• pp.224-238
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• 1987

본 논문에서 제안된 스펙트럼 분석장치는 개루프 방식의 VCO를 모듈러 함수를 이용한 PLL 주파수 합성기로 대치시킴으로써 단일루우프의 주파수 합성기로 개개의 다른 주파수 대역 및 채널간격을 얻을 수 있었다. 스펙트럼의 추출은 자승검파방식을 이용함으로써 종래의 포락선 검파방식보다 입력감도를 개선할 수 있었고 Z80 마이크로프로세서를 이용한 제어기는 주파수 합성기를 제어하는 동시에 추출된 스펙트럼을 메모리에 저장함으로써 비주기성 신호의 분석을 가능케 하였다.