• Title/Summary/Keyword: SAR116

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Depth-Specific Distribution of the SAR116 Phages Revealed by Virome Binning

  • Kang, Ilnam;Cho, Jang-Cheon
    • Journal of Microbiology and Biotechnology
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    • v.24 no.5
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    • pp.592-596
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    • 2014
  • HMO-2011, a recently isolated lytic phage that infects the SAR116 bacterial clade, represents one of the most abundant phage types in the oceans. In this study, the HMO-2011 genome sequence was compared with virome sequences obtained from various depths of the Pacific Ocean regions using metagenome binning. HMO-2011 was confirmed to be one of the most highly assigned viruses, with a maximum of 7.6% of total reads assigned. The HMO-2011-type phages demonstrated a depth-specific distribution, showing more abundance in the euphotic zone of coastal, transition, and open ocean regions as compared with the dark ocean.

Assessment of DEM Generated by Stereo C-band and X-band SAR images using Radargrammetry (Radargrammetry를 이용한 C-밴드 및 X-밴드 SAR 위성영상의 DEM 생성 평가)

  • Song, Yeong Sun;Kim, Gi Hong
    • Journal of Korean Society for Geospatial Information Science
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    • v.21 no.4
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    • pp.109-116
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    • 2013
  • To extract the 3D geometric information from SAR(Synthetic Aperture Radar) images, two different techniques, interferometric SAR and radargrammetry, have been widely used. InSAR is most widely used for the generation of precise DEM(Digital Elevation Model) until now. But, Interferometric SAR requires severe temporal correlation over areas covered with vegetation and high relief areas. Because radargrammetry is less sensible to temporal correlation, it can provide better results than interferometric SAR in certain, especially X-band SAR. In this paper, we assess the properties of DEMs generated by radargrammetry using stereo C-band RADARSAT-1 images and X-band TerraSAR-X images.

A Study of T/R Module Output Compensation Method for Active Synthetic Aperture Radar (능동형 SAR 시스템의 송수신 모듈 출력 보정 방법 연구)

  • Yi, Dong-Woo;Lee, Jong-Hwan;Kim, Se-Young;Jeon, Byoung-Tae
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.21 no.9
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    • pp.955-964
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    • 2010
  • In this paper, a compensation method of the amplitude and phase errors from the T/R(Transmit/Receive) modules in an active SAR(Synthetic Aperture Radar) system is introduced. The errors are defined and classified, and characterized by analyzing the measurement data acquired from the pilot test. To compensate these errors, a control methodology of T/R modules output is proposed. Before the compensation is applied, 16 T/R modules integrated on the active SAR antenna show the amplitude in 28.2~29.0 dBm and the phase in $101.7^{\circ}{\sim}165.2^{\circ}$. After the compensation, the amplitude and phase are distributed in 27.4~28.0 dBm and $116.1^{\circ}{\sim}120.0^{\circ}$ respectively. The antenna beam patterns generated by the array theory with the distributions are compared, and the proposed method is verified as good to apply for the active SAR system.

A Study on Freeze-Thaw Conditions Analysis of Soil Using Sentinel-1 SAR and Surface State Factor (Sentinel-1 SAR와 지표상태인자를 활용한 토양의 동결 융해 상태 분석 연구)

  • Yonggwan Lee;Jeehun Chung ;Wonjin Jang ;Jinuk Kim;Seongjoon Kim
    • Korean Journal of Remote Sensing
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    • v.39 no.5_1
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    • pp.609-620
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    • 2023
  • In this study, we used Sentinel-1 C-band synthetic aperture radar to calculate the surface state factor (SSF) for distinguishing the frozen-thawed state of soil. The accuracy of SSF classification was analyzed through comparison with air temperature (AT), grass temperature (GT), and underground temperature (UT). For the analysis, 116 Sentinel-1B Descending nodes observed over a period of 4 years from 2017 to 2020 were established for the central region of South Korea. AT, GT, and UT data were obtained from 23 soil moisture observation points of the Rural Development Administration during the same period, and analyzed using the 06:00 am data adjacent to the shooting time of the Sentinel-1B images. The average accuracy and F1-score for all stations were 0.63 and 0.47 for AT, 0.63 and 0.48 for GT, and 0.57 and 0.21 for UT, respectively. For winter (December-February) data, the average accuracy and F1-score were 0.66 and 0.76 for AT, 0.67 and 0.76 for GT, and 0.47 and 0.44 for UT, respectively. The increase in accuracy during winter data may be attributed to the fact that errors occurring in other seasons are not included.

Satellite Radar Interferometry for Mine Subsidence Monitoring

  • Ge Linlin
    • Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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    • 2005.02a
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    • pp.73-116
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    • 2005
  • [ $\blacksquare$ ] The integration of radar interferometry(InSAR), GIS and GPS can be used as an operational technology to monitor ground deformation due to underground mining, earthquakes, and so on, at sub-centimetre of mm level accuracy; $\blacksquare$ Operational procedures and tools have been developed and tested at UNSW; and $\blacksquare$ We are very keen to promote the technology together with you all.

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High-resolution Spiral-scan Imaging at 3 Tesla MRI (3.0 Tesla 자기공명영상시스템에서 고 해상도 나선주사영상)

  • Kim, P.K.;Lim, J.W.;Kang, S.W.;Cho, S.H.;Jeon, S.Y.;Lim, H.J.;Park, H.C.;Oh, S.J.;Lee, H.K.;Ahn, C.B.
    • Investigative Magnetic Resonance Imaging
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    • v.10 no.2
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    • pp.108-116
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    • 2006
  • Purpose : High-resolution spiral-scan imaging is performed at 3 Tesla MRI system. Since the gradient waveforms for the spiral-scan imaging have lower slopes than those for the Echo Planar Imaging (EPI), they can be implemented with the gradient systems having lower slew rates. The spiral-scan imaging also involves less eddy currents due to the smooth gradient waveforms. The spiral-scan imaging method does not suffer from high specific absorption rate (SAR), which is one of the main obstacles in high field imaging for rf echo-based fast imaging methods such as fast spin echo techniques. Thus, the spiral-scan imaging has a great potential for the high-speed imaging in high magnetic fields. In this paper, we presented various high-resolution images obtained by the spiral-scan methods at 3T MRI system for various applications. Materials and Methods : High-resolution spiral-scan imaging technique is implemented at 3T whole body MRI system. An efficient and fast higher-order shimming technique is developed to reduce the inhomogeneity, and the single-shot and interleaved spiral-scan imaging methods are developed. Spin-echo and gradient-echo based spiral-scan imaging methods are implemented, and image contrast and signal-tonoise ratio are controlled by the echo time, repetition time, and the rf flip angles. Results : Spiral-scan images having various resolutions are obtained at 3T MRI system. Since the absolute magnitude of the inhomogeneity is increasing in higher magnetic fields, higher order shimming to reduce the inhomogeneity becomes more important. A fast shimming technique in which axial, sagittal, and coronal sectional inhomogeneity maps are obtained in one scan is developed, and the shimming method based on the analysis of spherical harmonics of the inhomogeneity map is applied. For phantom and invivo head imaging, image matrix size of about $100{\times}100$ is obtained by a single-shot spiral-scan imaging, and a matrix size of $256{\times}256$ is obtained by the interleaved spiral-scan imaging with the number of interleaves of from 6 to 12. Conclusion : High field imaging becomes increasingly important due to the improved signal-to-noise ratio, larger spectral separation, and the higher BOLD-based contrast. The increasing SAR is, however, a limiting factor in high field imaging. Since the spiral-scan imaging has a very low SAR, and lower hardware requirements for the implementation of the technique compared to EPI, it is suitable for a rapid imaging in high fields. In this paper, the spiral-scan imaging with various resolutions from $100{\times}100$ to $256{\times}256$ by controlling the number of interleaves are developed for the high-speed imaging in high magnetic fields.

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Research on Spatial Dependence and Influencing Factors of Korean Intra-Industry Trade of Agricultural Products: From South Korea's Agricultural Trade Data

  • Lv, Hong-Qu;Huang, Chen-Yang
    • Journal of Korea Trade
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    • v.25 no.3
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    • pp.116-133
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    • 2021
  • Purpose - Intra-industry trade of agricultural products can eliminate the disadvantage of Korea's traditional agriculture and improve its lack of comparative advantage. The main purpose of this paper is to measure the level and index of intra-industry trade of Korean agricultural products and to explore the spatial dependence and spillover effect associated with this type of trade. The main factors influencing intra-agricultural trade are analyzed from two perspectives: the population and the classification of agricultural products. Design/methodology - First, the level of intra-industry trade of Korean agricultural products is measured. Second, to obtain a more accurate estimate of the influence of various factors, and based on two types of weight matrices, a spatial econometric model is constructed from two aspects: population and classification of agricultural products. The status and the factors influencing intra-industry trade are also studied. Findings - It is concluded that there is a positive spatial correlation between Korea's intra-industry trade in agricultural products and that of its trading partners. The spatial spillover effect of this type of trade is verified by using the spatial autoregressive model (SAR). Labor-intensive agricultural products are found to have a positive spillover effect on intra-industry trade, while land-intensive products do not have a significant effect. Originality/value - In this paper, the two types of agricultural products are meticulously distinguished, and the spatial effect of the intra-industry trade of agricultural products as well as the influence of various factors are analyzed. In addition, the accuracy of the estimation of the coefficients of the factors by using the spatial econometric model is higher than that of the ordinary panel data model.

SIEVING NONLINEAR INTERNAL WAVES IN SATELLITE IMAGES

  • Liu, Cho-Teng;Chao, Yen-Hsiang;Hsu, Ming-Kuang;Chen, Hsien-Wen
    • Proceedings of the KSRS Conference
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    • v.2
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    • pp.820-823
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    • 2006
  • Nonlinear internal waves (NLIW) were studied as a unusual phenomena in the ocean decades ago. As the quality, quantity and variety of satellite images improve over decades, it is founded that NLIW is a ubiquitous phenomenon. Over the continental shelf of northern South China Sea (SCS), both optical and microwave images show that there are trains of NLIW packets near Dongsha Atoll (20.7N, 116.8E). Each packet contains several NLIW fronts. These NLIW packets are nearly parallel to each other and they are refracted, reflected or diffracted by the change of ocean bottom topography. Based on Korteweg de Vries (KdV) theory and the assumption that the bright/dark lines in the satellite images are centers of convergence/divergence of NLIW fronts, one may (1) sort NLIW packets in the same satellite image into groups of the same source, but generated at different tidal cycles, (2) relate NLIW packets in consecutive satellite images of one day apart, (3) locating faint signals of NLIW fronts in a satellite image. The NLIWs travel more than 100 km/day near Dongsha Atoll, with higher speed in deeper water. The bias and standard deviation of predicted location of NLIW front from its true location is about 1% and 5.1%, respectively.

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Effects of Interruption Layer for Capillary Rise on Salt Accumulation and Kentucky Bluegrass Poa pratensis Growth in Sand Growing Media over the Reclaimed Saline Soil (임해 간척지에서 모래상토 층에 모세관수 차단 층의 도입이 염류 집적과 켄터 키블루그래스 생육에 미치는 영향)

  • Rahayu, Rahayu;Yang, Geun-Mo;Choi, Joon-Soo
    • Asian Journal of Turfgrass Science
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    • v.24 no.2
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    • pp.106-116
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    • 2010
  • This research was conducted to determine the effect of interruption layer for capillary rise on the sand based growing media when growing Kentucky bluegrass (Poa pratensis L.) on soil reclamation and saline water irrigation. Growing media profile consists of three layers as top soil of 30 cm, 20 cm of the interruption layer for capillary rise and 10 cm of reclaimed paddy soil. Growing media profile was packed in 30 cm diameter column pots. The top soil was a mixture of sand dredged up from Lake Bhunam Tae Ahn, Korea and peat at the ratio of 95:5 by volume. Bottom part of column was covered with plastic net and the pots were soaked into 5 cm depth saline water reservoir with salinity $3-5\;dS\;m^{-1}$. Kentucky bluegrass was established by sod and irrigated using $2\;dS\;m^{-1}$ saline water ($5.7\;mm\;day^{-1}$) in 3 days interval. The results showed that the largest accumulation of salt in the spring with electrical conductivity in saturated extract (ECe) of $5.4\;dS\;m^{-1}$ and sodium absorption ratio (SAR) 34.0 in growing media without the interruption layer for capillary rise and ECe of $4.6\;dS\;m^{-1}$ and SAR 8.24 at growing media using gravel as the interruption layer for capillary rise material. The interruption layer for capillary rise of gravel and coarse sand reduced the accumulation of Na by 16% and 25%, ECe by 7% and 13% in the growing media. Visual quality of Kentucky bluegrass was higher in growing media with the interruption layer for capillary rise of gravel than no interruption layer by 8.3 compared to 7.9 in rates. The interruption layer for capillary rise of gravel and coarse sand enhanced the visual quality by 4.1 and 4.0%, root length by 50 and 38%, and root dry weight by 35 and 17% of Kentucky bluegrass, and reduced the accumulation of Na by 16% and 25%, ECe by 7% and 13% in the growing media.