• Proceedings of the KSRS Conference
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• 2009.03a
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• pp.40-45
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• 2009

본 연구에서는 기후 등의 영향을 받지 않고 레이더 산란 측정을 할 수 있는 X-band antenna 기반의 자동관측 시스템을 이용하여 벼 생육시기에 따른 후방산란계수와 벼 생육인자와의 관계를 분석하여 후방산란계수를 이용한 벼 생육인자를 추정한 것을 목적으로 하였다. 2008년도 국립농업과학원 시험포장 ($37^{\circ}$15'28.0"N, $126^{\circ}$59'21.5"E)에서 추청벼를 대상으로 생육시기별 후방산란계수를 관측하였는데 모든 편파별 후방산란계수가 벼 유수형성기 (7월 말경)까지 증가하다가 그 후 감소하다가 수확기가 가까워지는 9월 중순이후 다시 증가하는 dual-peak 현상을 보였고 특히 W-편파의 경우 9월 초순부터 후방산란계수 증가가 다른 polarization에 비해 크게 나타났다. 후방산란계수와 작물생육인자와의 관계를 분석한 결과 고주파수인 X-band는 상대적으로 바이오메스, 엽 면적지수와의 상관이 낮게 나타났지만 이삭 건물중은 VV-편파 후방산란계수와 상관관계를 보였다. 이삭 건물중과 상관관계가 높게 나타난 X-band의 W-편파 후방산란계수를 이용하여 수확기 이삭 건물중을 추정하였는데 VV-편파 후방산란계수와 이삭 건물중과는 결정계수 $(R^2)$가 0.85이었고, 이삭 건물중 실측값과 추정값을 비교해 본 결과 1:1 line에 근접하게 분포하였다 ($R^2$=0.85).

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.2
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• pp.127-134
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• 2012

Microwave remote sensing can help monitor the land surface water cycle, crop growth and soil moisture. A ground-based polarimetric scatterometer has an advantage for continuous crop using multi-polarization and multi-frequencies and various incident angles have been used extensively in a frequency range expanding from L-band to Ka-band. In this study, we analyzed the relationships between L-, C- and X-band signatures and soil moisture content over the whole soybean growth period. Polarimetric backscatter data at L-, C- and X-bands were acquired every 10 minutes. L-band backscattering coefficients were higher than those observed using C- or X-band over the period. Backscattering coefficients for all frequencies and polarizations increased until Day Of Year (DOY) 271 and then decreased until harvesting stage (DOY 294). Time serious of soil moisture content was not a corresponding with backscattering over the whole growth stage, although it increased relatively until early August (R2, DOY 224). We conducted the relationship between the backscattering coefficients of each band and soil moisture content. Backscattering coefficients for all frequencies were not correlated with soil moisture content when considered over the entire stage ($r{\leq}0.50$). However, we found that L-band HH polarization was correlated with soil moisture content (r=0.90) when Leaf Area Index (LAI)<2. Retrieval equations were developed for estimating soil moisture content using L-band HH polarization. Relation between L-HH and soil moisture shows exponential pattern and highly related with soil moisture content ($R^2=0.92$). Results from this study show that backscattering coefficients of radar scatterometer appear effective to estimate soil moisture content.

• Korean Journal of Optics and Photonics
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• v.10 no.5
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• pp.357-363
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• 1999

A frequency domain spectroscopic system was constructed to investigate the optical properties of multiple scattering media. The alternating current (AC) and phase lag components of backscattered light were measured by using the heterodyne detection method. Absorption and transport scattering coefficients were computed from the values based on diffusion theory. Predictions showed excellent matches in comparison with actual values of absorption and scattering. Predictable ranges of the optical coefficients were analyzed in terms of the distance between light source and detector, and modulation frequencies. A proposed compact experimental set-up using laser diodes can be utilized to estimate non-invasively the optical properties of multiple scattering media such as biological tissues.

• Korean Journal of Soil Science and Fertilizer
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• v.43 no.3
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• pp.374-383
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• 2010

Microwave radar can penetrate cloud cover regardless of weather conditions and can be used day and night. Especially a ground-based polarimetric scatterometer has advantages of monitoring crop conditions continuously with full polarization and different frequencies. Kim et al. (2009) have measured backscattering coefficients of paddy rice using L-, C-, X-band scatterometer system with full polarization and various angles during the rice growth period and have revealed the necessity of near-continuous automatic measurement to eliminate the difficulties, inaccuracy and sparseness of data acquisitions arising from manual operation of the system. In this study, we constructed an X-band automatic scatterometer system, analyzed scattering characteristics of paddy rice from X-band scatterometer data and estimated rice growth parameter using backscattering coefficients in X-band. The system was installed inside a shelter in an experimental paddy field at the National Academy of Agricultural Science (NAAS) before rice transplanting. The scatterometer system consists of X-band antennas, HP8720D vector network analyzer, RF cables and personal computer that controls frequency, polarization and data storage. This system using automatically measures fully-polarimetric backscattering coefficients of rice crop every 10 minutes. The backscattering coefficients were calculated from the measured data at a fixed incidence angle of $45^{\circ}$ and with full polarization (HH, VV, HV, VH) by applying the radar equation and compared with rice growth data such as plant height, stem number, fresh dry weight and Leaf Area Index (LAI) that were collected at the same time of each rice growth parameter. We examined the temporal behaviour of the backscattering coefficients of the rice crop at X-band during rice growth period. The HH-, VV-polarization backscattering coefficients steadily increased toward panicle initiation stage, thereafter decreased and again increased in early-September. We analyzed the relationships between backscattering coefficients in X-band and plant parameters and predicted the rice growth parameters using backscattering coefficients. It was confirmed that X-band is sensitive to grain maturity at near harvesting season.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.18 no.10
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• pp.1454-1460
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• 1993

The scattering pattern, due to an E-Polarized wave incident on M circular parallel dielectric cylinders, is computed. The multiply-scattered fields between the cylinders are considered. Modeling of infinite cylindrical scatterer of arbitrary cross sections by a number of circular cylinders is executed. By enforcing the boundary conditions on the surface of each cylinder, an infinite set of equations is obtained. The first order of scattering results from the excitation of each cylinder by only the incident wave. The second order results from the excitation of each cylinder by the first order of scattering from the remaining cylinders, and so no to an infinite order of scattering. Although the resulting equation is of infinite size, proper truncation yields very accurate numerical results.

• Proceedings of the KSRS Conference
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• 2006.03a
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• pp.75-78
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• 2006

이 연구에서는 Radarsat-1 SAR 영상과 조위자료, 증발자료 및 다편광 산란계를 이용한 개펄 건조 실내실험 등을 통하여 해수면 위로 노출된 자연갯벌이 증발과 구조적 변화를 일으킬 때 레이더 후방산란계수의 변화를 분석하였다. 개펄 건조 실내실험 결과, 후방산란계수가 증발시간에 따라 단순한 증가나 감소를 보이지 않았으며 갯벌의 구조와 배수, 증발, 건조 등에 의해 보다 복잡한 M자 형태(증가-감소-증가-감소)의 변화를 나타내었다. 이러한 M형의 변화는 증발시간에 따른 Radarsat-1 SAR 15개 영상의 후방산란계수 변화 양상에서도 나타나는 것으로 확인되었다.

• Journal of Biomedical Engineering Research
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• v.18 no.4
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• pp.499-505
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• 1997

A non-invasive technique to measure absorption and scattering coefficients was investigated The reflected backscattered light from the surface of phantom and biological tissue was obtained by using a time-correlated single photon counting system in pico-second time domain. The absorption and scattering coefficients were acquired by the time of peak and asymptotic behavior of the time-resolved reflectance curve and agreed well the ones that is obtained with deconvolution method It was found that the approximation method was good for biological medium to calculate optical properties due to its convenience and accuracy.

• 대한방사선방어학회:학술대회논문집
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• 2011.04a
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• pp.78-79
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• 2011

• Proceedings of the Acoustical Society of Korea Conference
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• 1992.06a
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• pp.96-99
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• 1992

섬유강화 복합재료의 동탄성계수와 감쇠특성을 규명하기 위하여 랜덤하게 분포된 무한 실린더 형상의 산란체를 가진 매질내에서, 조화운동을 하는 압축 및 SV탄성파의 전파에 관하여 연구하였다. 단일 실린더에 대한 산란계수로부터 La의 준결정근사법을 이용하여 다중산란에 관한 이론을 유도하였고, 매질내에서의 파동전파 특성을 내포하는 분산관계식을 얻었다. 수치적으로 분산관계식의 해를 구함으로써 2 차원 유효체적강성, 횡방향 유효전단강성 및 각 파동의 전파에 따른 감쇠계수를 주파수와 체적비의 함수로서 제시하였다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.1
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• pp.9-15
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• 2011

This paper suggested the fast and easy method of the dielectric constant measurement for planar dielectrics using a microstrip line. The complex permittivity and permeability were presented by the first reflection and transmission coefficient which were derived from the scattering parameters. This method was verified by the measurement of a known planar dielectric using a microstrip line. This method can be applied to the dielectric constant measurement of unknown planar dielectric.