• 융합신호처리학회논문지
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• 제19권2호
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• pp.68-76
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• 2018

본 논문에서는 대전상관기의 다중 편파 관측데이터의 상관처리 방법에 대해 기술한다. VLBI 관측에는 천체의 종류에 따라 단일 또는 다중 편파 관측이 있는데, 천체의 특성을 잘 관찰하기 위해 편파관측을 수행한다. 그리고 천체를 관측하는 동안 관측장치에 포함된 지연값과 천체의 변동원인을 확인하기 위해서도 편파관측을 수행한다. 대전상관기의 편파관측 데이터의 상관처리는 각 안테나 유닛에 입력되는 데이터를 출력하는 동기재생처리장치의 OCTAVIA에서 출력비트 선택 기능을 활용하여 비트를 변환하고, 이때 데이터 스트림(Stream)의 순서가 변경되며, 대전상관기의 입력은 기존의 스트림 번호는 동일하게 설정하여 상관처리를 수행하면 편파상관처리를 할 수 있는 구성을 제안하였다. 편파상관처리를 위해 관측한 시험데이터를 대상으로 상관처리를 수행하였으며, 본 연구에서 제안한 대전상관기의 편파상관처리 방법이 유효하게 동작하고 있음을 실험을 통하여 확인하였다.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2008년도 춘계학술대회 논문집
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• pp.180-184
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• 2008

Preliminary results are reported on ship detection using coherence images computed from crosscorrelating images of multi-look-processed dual-polarization data (HH and HV) of ENVISAT ASAR. The traditional techniques of ship detection by radars such as CFAR (Constant False Alarm Rate) rely on the amplitude data, and therefore the detection tends to become difficult when the amplitudes of ships images are at similar level as the mean amplitude of surrounding sea clutter. The proposed method utilizes the property that the multi-look images of ships are correlated with each other. Because the inter-look images of sea surface are covered by uncorrelated speckle, crosscorrelation of multi-look images yields the different degrees of coherence between the images and water. The polarimetric information of ships, land and intertidal zone are first compared based on the cross-correlation between HH and HV. In the next step, we examine the technique when the dual-polarization data are split into two multi-look images.

• 대한원격탐사학회지
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• 제24권5호
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• pp.445-452
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• 2008

Preliminary results are reported on ship detection using coherence images computed from cross-correlating images of multi-look-processed dual-polarization data (HH and HV) of ENVISAT ASAR. The traditional techniques of ship detection by radars such as CFAR (Constant False Alarm Rate) rely on the amplitude data, and therefore the detection tends to become difficult when the amplitudes of ships images are at similar level as the mean amplitude of surrounding sea clutter. The proposed method utilizes the property that the multi-look images of ships are correlated with each other. Because the inter-look images of sea surface are covered by uncorrelated speckle, cross-correlation of multi-look images yields the different degrees of coherence between the images and water. In this paper, the polarimetric information of ships, land and intertidal zone are first compared based on the cross-correlation between HH and HV images, In the next step, we examine the technique when the dual-polarization data are split into two multi-look images, It was shown that the inter-look cross-correlation method could be applicable in the performance improvement of small ship detection and the land masking, It was also found that a simple combination of coherence images from each co-polarised (HH) inter-look and cross-polarised (HV) inter-look data can provide much higher target-detection possibilities.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2007년도 Proceedings of ISRS 2007
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• pp.262-265
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• 2007

Preliminary results are reported on ship detection using coherence images computed from cross-correlating images of multi-look-processed dual-polarization data (HH and HV) of ENVISAT ASAR. The traditional techniques of ship detection by radars such as CFAR (Constant False Alarm Rate) rely on the amplitude data, and therefore the detection tends to become difficult when the amplitudes of ships images are at similar level as the mean amplitude of surrounding sea clutter. The proposed method utilizes the property that the multi-look images of ships are correlated with each other. Because the inter-look images of sea surface are covered by uncorrelated speckle, cross-correlation of multi-look images yields the different degrees of coherence between the images and water. The polarimetric information of ships, land and intertidal zone are first compared based on the cross-correlation between HH and HV. In the next step, we examine the technique when the dual-polarization data are split into two multi-look Images.

• 한국토양비료학회지
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• 제47권2호
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• pp.85-91
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• 2014

Ground-based polarimetric scatterometers have been effective tools to monitor the growth of crop with multi-polarization and frequencies and various incident angles. An important advantage of these systems that can be exploited is temporal observation of a specific crop target. Polarimetric backscatter data at L-, C- and X-bands were acquired every 10 minutes. We analyzed the relationships between L-, C- and X-band signatures, biophysical measurements over the whole corn growth period. The Vertical transmit and Vertical receive polarization (VV) backscattering coefficients for all bands were greater than those of the Horizontal transmit and Horizontal receive polarization (HH) until early-July, and then thereafter HH-polarization was greater than VV-polarization or Horizontal transmit and Vertical receive polarization (HV) until the harvesting stage (Day Of Year, DOY 240). The results of correlation analysis between the backscattering coefficients for all bands and corn growth data showed that L-band HH-polarization (L-HH) was the most suited for monitoring the fresh weight ($r=0.95^{***}$), dry weight ($r=0.95^{***}$), leaf area index ($r=0.86^{**}$), and vegetation water content ($r=0.93^{***}$). Retrieval equations were developed for estimating corn growth parameters using L-HH. The results indicated that L-HH could be used for estimating the vegetation biophysical parameters considered here with high accuracy. Those results can be useful in determining frequency and polarization of satellite Synthetic Aperture Radar stem and in designing a future ground-based microwave system for a long-term monitoring of corn.

• 한국토양비료학회지
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• 제47권4호
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• pp.235-241
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• 2014

A ground-based microwave scatterometer has an advantage for monitoring soil moisture content using multi-polarization, multi-frequencies and various incidence angles. In this paper, ground-based multi-frequency (L-, C-, and X-band) polarimetric scatterometer system capable of making observations every 10 min was used to monitor the soil moisture conditions in a corn field over an entire growth cycle. Measurements of volumetric soil moisture were obtained and their relationships to the backscatter observations were examined. Time series of soil moisture content was not corresponding with backscattering coefficient pattern over the whole growth stage, although it increased until early July (Day Of Year, DOY 160). We examined the relationship between the backscattering coefficients from each band and soil moisture content of the field. Backscattering coefficients for all bands were not correlated with soil moisture content when considered over the entire stage ($r{\leq}0.48$). However, L-band Horizontal transmit and Horizontal receive polarization (HH) had a good correlation with soil moisture ($r=0.85^{**}$) when LAI was lower than 2. Prediction equations for soil moisture were developed using the L-HH data. Relation between L-HH and soil moisture shows linear pattern and related with soil moisture content ($R^2=0.77$). Results from this study show that backscattering coefficients of microwave scatterometer appear to be effective to estimate soil moisture content in the field level.

• 한국광학회:학술대회논문집
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• 한국광학회 2008년도 하계학술발표회 논문집
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• pp.187-189
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• 2008

The spatial coherence function of multy-mode beam was measured by using a Sagnac interferometer and self referencing technique. For leaner polarization laser beam passing through a multy-mode fiber, its change value of spatial mode and polarization from stress of faber and input coupling angle. And each spatial mode have each polarizations, when we simulation Wigner distribution function and Spatial Correlation function of spatial multi-mode beam by using Hermit Gaussian modes leaner sum. We measured spatial coherence function of using by multy-mode fiber. One can use this measurement method to study and characterize the property of multy-mode light field coming out of GRIN multy-mode fiber.

• Bulletin of the Korean Chemical Society
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• 제35권5호
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• pp.1422-1432
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• 2014

Convergent all-electron multi-reference configuration-interaction (MRCI) calculations are performed for a lithium dimer with Kaufmann's Rydberg basis functions. A comparison of the results of these calculations with those of the effective core potential/core polarization potential (ECP/CPP) method and experimental data reveals the deficiency of the all-electron ab initio method. The deficiency is related to the mere 51.9% attainment of electron correlation for the ground state. The percent attainment of electron correlation for the first excited state is slightly better than that for the ground state, preventing us from obtaining better agreements with experimental data by means of increasing the size of basis sets. The Kaufmann basis functions are then used with the ECP/CPP method to obtain the accurate convergent potential energy curves for the $^1\prod_u$ states correlated to Li(2p) + Li(2p) and Li(2s) + Li(n = 2, 3, 4). Quantum defect curves (QDCs) calculated for both the $X^2\sum_g$ and 1 $^2\prod_u$ states of the $Li{_2}^+$ ion and the Lu-Fano plot reveal a strong series-series interaction between the two $2snp{\pi}$ and $2pnp{\pi}$ Rydberg series. The QDCs are then used to resolve assignment problems in the literature. The reassignments, performed by Jedrzejewski-Szemek et al., of the dissociation product of the D $^1\prod$ state from (2s+3d) to (2s+3p) and that of the 6 $^1\prod_u$ from (2s+4d) to (2s+4p) are found to be incorrect. It may be more natural to assign their $2snp{\pi}$ Rydberg series as a $2snd{\pi}$ series. The state, assigned as 5p $^1\prod_u$ by Ross et al. and 4d $^1\prod$ by Jedrzejewski-Szemek et al., is assigned as the 7 $^1\prod_u$ state, correlated to the Li(2s) + Li(4f) limit.

• Current Optics and Photonics
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• 제7권4호
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• pp.362-377
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• 2023

Optical information processing technology is characterized by high speed and parallelism, and the light features short wavelength and large information capacity; At the same time, it has various attributes including amplitude, phase, wavelength and polarization, and is a carrier of multi-dimensional information. Therefore, optical encryption is of great significance in the field of information security transmission, and is widely used in the field of image encryption. For multi-image encryption, this paper proposes a multi-image encryption algorithm based on a modified Gerchberg-Saxton algorithm (MGSA) in the Fresnel-transform domain and computational ghost imaging. First, MGSA is used to realize "one code, one key"; Second, phase function superposition and normalization are used to reduce the amount of ciphertext transmission; Finally, computational ghost imaging is used to improve the security of the whole encryption system. This method can encrypt multiple images simultaneously with high efficiency, simple calculation, safety and reliability, and less data transmission. The encryption effect of the method is evaluated by using correlation coefficient and structural similarity, and the effectiveness and security of the method are verified by simulation experiments.

• 한국토양비료학회지
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• 제46권1호
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• pp.23-31
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• 2013

L, C, X-밴드 마이크로파 산란계 자동측정시스템을 이용하여 밀 생육시기에 따른 밴드 및 편파별 후방산란계수와 생육인자 변화를 측정하였다. 모든 안테나 밴드에서 밀 생육 초기에는 VV-편파가 HH, HV-편파보다 후방산란계수가 높게 나타났다. HH-편파가 VV-편파보다 후방산란계수가 높게 나타나는 시기는 밴드에 따라 차이를 보였다. L-밴드의 경우 3월 28일 (DOY 88), C, X-밴드는 4월 2일 (DOY 93)부터 HH-편파가 다른 편파들 보다 후방산란계수가 높게 나타났다. 모든 안테나에서 편파별 후방산란계수가 5월 16일 (DOY 137)에 최대값을 보였고 그 이후 수확기 (DOY 174, 6월 22일)까지 감소하였는데 초장, 생체중, 건물중, 엽면적지수 등 밀 생육인자들에서도 동일한 경향이 나타났다. 밴드별 후방산란계수와 밀 생육인자들과의 상관관계를 분석한 결과 L-밴드 HH-편파에서 생체중 (r=0.98), 건물중 (r=0.96), 식생 수분함량 (r=0.98) 초장 (r=0.96) 등 모든 밀 생육인자들과 상관계수가 가장 높게 나타났다. L-밴드 HH-편파 후방산란계수를 이용하여 밀 생육인자를 추정한 결과 생체중 ($R^2$=0.98), 건물중 ($R^2$=0.95), 식생 수분함량($R^2$=0.98) 초장 ($R^2$=0.95)의 결정계수가 각각 높게 나타났다. L-밴드 HH-편파 후방산란계수를 이용하는 것이 밀 생육을 가장 높게 예측할 수 있었음을 확인하였다.