• Journal of Microbiology and Biotechnology
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• v.24 no.9
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• pp.1216-1225
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• 2014

Biofilm-related infections of Candida albicans are a frequent cause of morbidity and mortality in hospitalized patients, especially those with immunocompromised status. Options of the antifungal drugs available for successful treatment of drug-resistant biofilms are very few, and as such, new strategies need to be explored against them. The aim of this study was to evaluate the efficacy of phenylpropanoids of plant origin against planktonic cells, important virulence factors, and biofilm forms of C. albicans. Standard susceptibility testing protocol was used to evaluate the activities of 13 phenylpropanoids against planktonic growth. Their effects on adhesion and yeast-to-hyphae morphogenesis were studied in microplate-based methodologies. An in vitro biofilm model analyzed the phenylpropanoid-mediated prevention of biofilm development and mature biofilms using XTT-metabolic assay, crystal violet assay, and light microscopy. Six molecules exhibited fungistatic activity at ${\leq}0.5mg/ml$, of which four were fungicidal at low concentrations. Seven phenylpropanoids inhibited yeast-to-hyphae transition at low concentrations (0.031-0.5 mg/ml), whereas adhesion to the solid substrate was prevented in the range of 0.5-2 mg/ml. Treatment with ${\leq}0.5mg/ml$ concentrations of at least six small molecules resulted in significant (p < 0.05) inhibition of biofilm formation by C. albicans. Mature biofilms that are highly resistant to antifungal drugs were susceptible to low concentrations of 4 of the 13 molecules. This study revealed phenylpropanoids of plant origin as promising candidates to devise preventive strategies against drug-resistant biofilms of C. albicans.

• Korean Journal of Remote Sensing
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• v.33 no.1
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• pp.69-77
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• 2017

S The need for an automated geo-positioning approach for near real-time results and to boost cost-effectiveness has become increasingly urgent. Following this trend, a new approach to automatically compensate for the bias of the rational function model (RFM) was proposed. The core idea of this approach is to remove the bias of RFM only using tie points, which are corrected by matching with the digital elevation model (DEM) without any additional ground control points (GCPs). However, there has to be a additional evaluation according to the quality of DEM because DEM is used as a core element in this approach. To address this issue, this paper compared the quality effects of DEM in the conduct of the this approach using the Shuttle Radar Topographic Mission (SRTM) DEM with the spatial resolution of 90m. and the National Geographic Information Institute (NGII) DEM with the spatial resolution of 5m. One KOMPSAT-2 stereo-pair image acquired at Busan, Korea was used as experimental data. The accuracy was compared to 29 check points acquired by GPS surveying. After bias-compensation using the two DEMs, the Root Mean Square (RMS) errors were less than 6 m in all coordinate components. When SRTM DEM was used, the RMSE vector was about 11.2m. On the other hand, when NGII DEM was used, the RMSE vector was about 7.8 m. The experimental results showed that automated geo-positioning approach can be accomplished more effectively by using NGII DEM with higher resolution than SRTM DEM.

• Journal of Microbiology and Biotechnology
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• v.27 no.4
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• pp.685-693
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• 2017

Candidiasis involving the biofilms of Candida albicans is a threat to immunocompromised patients. Candida biofilms are intrinsically resistant to the antifungal drugs and hence novel treatment strategies are desired. The study intended to evaluate the anti-Candida activity of allyl isothiocyanate (AITC) alone and with fluconazole (FLC), particularly against the biofilms. Results revealed the concentration-dependent activity of AITC against the planktonic growth and virulence factors of C. albicans. Significant (p <0.05) inhibition of the biofilms was evident at ${\leq}1mg/ml$ concentrations of AITC. Notably, a combination of 0.004 mg/ml of FLC and 0.125 mg/ml of AITC prevented the biofilm formation. Similarly, the preformed biofilms were significantly (p <0.05) inhibited by the AITC-FLC combination. The fractional inhibitory concentration indices ranging from 0.132 to 0.312 indicated the synergistic activity of AITC and FLC against the biofilm formation and the preformed biofilms. No hemolytic activity at the biofilm inhibitory concentrations of AITC and the AITC-FLC combination suggested the absence of cytotoxic effects. The recognizable synergy between AITC and FLC offers a potential therapeutic strategy against biofilm-associated Candida infections.

• Proceedings of the KSRS Conference
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• 2008.10a
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• pp.196-199
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• 2008

Lineament is defined generally as a linear feature or pattern on interpretation of a satellite image and indicates the geological structures such as faults and fractures. For this reason, a lineament extraction and analysis using remote sensing images have been widely used for mapping large areas. The Gyeong-gang Fault is a NNE trending structure located in Gangwon-do and Kyeonggi-do district. However, a few geological researches on that fault have been carried out and its trace or continuity is ambiguous. In this study, we investigate the geologic features at Gyeong-gang Fault Zone using LANDSAT ETM+ satellite image and SRTM digital elevation model. In order to extract the characteristics of geologic features effectively, we transform the LANDSAT ETM+ image using Principal Component Analysis (PCA) and create a shade relief from SRTM data with various illumination angles. The results show that it is possible to identify the dimensions and orientations of the geologic features at Gyeong-gang Fault Zone using remote sensing data. An aerial photograph interpretation and a field work will be future tasks for more accurate analysis in this area.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.32 no.3
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• pp.217-223
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• 2014

With precise sensor position, attitude element, and imaging resolution, a simulated geospatial image can be generated. In this study, a satellite image is simulated using SPOT ortho-image and global elevation data, and the geometric similarity between original and simulated images is analyzed. Using a SPOT panchromatic image and high-density elevation data from a 1/5K digital topographic map data an ortho-image with 10-meter resolution was produced. The simulated image was then generated by exterior orientation parameters and global elevation data (SRTM1, GDEM2). Experimental results showed that (1) the agreement of the image simulation between pixel location from the SRTM1/GDEM2 and high-resolution elevation data is above 99% within one pixel; (2) SRTM1 is closer than GDEM2 to high-resolution elevation data; (3) the location of error occurrence is caused by the elevation difference of topographical objects between high-density elevation data generated from the Digital Terrain Model (DTM) and Digital Surface Model (DSM)-based global elevation data. Error occurrences were typically found at river boundaries, in urban areas, and in forests. In conclusion, this study showed that global elevation data are of practical use in generating simulated images with 10-meter resolution.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.32 no.1
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• pp.19-27
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• 2014

Kompsat-3 is an optical high-resolution earth observation satellite launched in May 2012. In addition to its 0.7m spatial resolution, Kompsat-3 is capable of in-track stereo acquisition enabling quality Digital Elevation Model(DEM) generation. Typical DEM generation procedure requires accurate control points well-distributed over the entire image region. But we often face difficult situations especially when the area of interests is oversea or inaccessible area. One solution to this is to use existing geospatial data even though they only cover a part of the image. This paper aimed to assess accuracy of DEM from Kompsat-3 with different scenarios including no control point, Rational Polynomial Coefficients(RPC) relative adjustment, and RPC adjustment with control points. Experiments were carried out for Kompsat-3 stereo data in USA. We used Digital Orthophoto Quadrangle(DOQ) and Shuttle Radar Topography Mission(SRTM) as control points sources. The generated DEMs are compared to a LiDAR DEM for accuracy assessment. The test results showed that the relative RPC adjustment significantly improved DEM accuracy without any control point. And comparable DEM could be derived from single control point from DOQ and SRTM, showing 7 meters of mean elevation error.

• Journal of the Korean GEO-environmental Society
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• v.17 no.9
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• pp.21-28
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• 2016

The purpose of this study is to compare the three areas that each estimated by using three different river topographic maps. For construction of river topographic maps, the data used in this study are ASTER, SRTM and a 1:5,000 scale digital map data sets in 14 streams of the Cheongdo-gun and Uiseong-gun. HEC-GeoRAS, RAS Mapper, and RiverCAD model are applied for the flooding area analysis using observed data and design rainfalls. The result of analysis is to compare observed flooding area based on the flood plain maps with estimated inundation area by hydraulic models and constructed river topographic maps. The results of this study are as follows; Flooding area by HEC-GeoRAS model is similar to the inundation area of flood plain map and appears in order of RAS Mapper, and RiverCAD model in all watersheds. Flood inundation area by SRTM DEM is similar to the result of 1:5,000 scale digital map in all watersheds and all analysis models. The SRTM DEM shows the most similarity to the digital map than ASTER DEM in all of the watershed scale and analysis models. HEC-GeoRAS and RiverCAD model are efficient models for flood inundation analysis in small watershed and HEC-GeoRAS and Ras Mapper model are efficient in medium to large watershed.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2006.04a
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• pp.277-280
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• 2006

항공사진이나 인공위성 영상을 이용하여 DEM을 생성하는 연구는 전통적으로 사진측량학 분야에서 이루어져 왔다. 즉, 항공기 및 위성을 이용하여 획득한 입체의 영상자료를 이용하여 DEM을 생성하는 기법은 전통적으로 행해져 왔고 최근에 들어서는 LIDAR를 이용하여 1m 급 이상의 정밀 DEM이 획득되고 있다. 그러나 자국 이외 지역에 대한 DEM 자료를 획득하는 일은 위성 및 항공기를 이용한 입체쌍의 영상자료, 기준점 등의 자료를 얻기가 힘들기 때문에 공간해상도가 90m인 USGS에서 제공하는 SRTM자료를 활용해야 하는 등 제한적이다. 이에, 본 연구에서는 공간해상도 15m의 DEM 생성이 가능한 ASTER 영상을 이용하여 중국지역에 대한 정밀 DEM을 생성하고자 하였다. ASTER 영상은 가시광선대, 적외선대 및 열밴드의 정보를 제공하고 있을 뿐만 아니라 DEM 제작을 위하여 위성진행 경로에 정방향 및 역방향의 입체 영상을 제공하고 있다. 이러한 ASTER 영상의 센서 정보와 접합점을 이용하여 DEM을 생성하였고, 이를 SRTM 자료와 동기화 하여 두 자료를 비교 분석하였다.

• Proceedings of the KSRS Conference
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• 2008.10a
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• pp.212-215
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• 2008

The final product generated from the KOMPSAT-2 Terminal for Polar System, K2PS, is an ellipsoid projected image. This leaves a relief displacement on the image by process of which the height value of subject area is constant. In this paper, orthorectification using the SRTM was used to remove such artifacts, and thereafter, the additional product that could be generated from the K2PS was discussed.

• Korean Journal of Remote Sensing
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• v.24 no.5
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• pp.483-496
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• 2008

Qualified ground control points (GCPs) are required to construct a digital elevation model (DEM) from a pushbroom stereo pair. An inverse geolocation algorithm for extracting GCPs from ERS SAR data and the SRTM DEM was recently developed. However, not all GCPs established by this method are accurate enough for direct application to the geometric correction of pushbroom images such as SPOT, IRS, etc, and thus a method for selecting and removing inaccurate points from the sets of GCPs is needed. In this study, we propose a method for evaluating GCP accuracy and winnowing sets of GCPs through orientation modeling of pushbroom image and validate performance of this method using SPOT stereo pair of Daejon City. It has been found that the statistical distribution of GCP positional errors is approximately Gaussian without bias, and that the residual errors estimated by orientation modeling have a linear relationship with the positional errors. Inaccurate GCPs have large positional errors and can be iteratively eliminated by thresholding the residual errors. Forty-one GCPs were initially extracted for the test, with mean the positional error values of 25.6m, 2.5m and -6.1m in the X-, Y- and Z-directions, respectively, and standard deviations of 62.4m, 37.6m and 15.0m. Twenty-one GCPs were eliminated by the proposed method, resulting in the standard deviations of the positional errors of the 20 final GCPs being reduced to 13.9m, 8.5m and 7.5m in the X-, Y- and Z-directions, respectively. Orientation modeling of the SPOT stereo pair was performed using the 20 GCPs, and the model was checked against 15 map-based points. The root mean square errors (RMSEs) of the model were 10.4m, 7.1m and 12.1m in X-, Y- and Z-directions, respectively. A SPOT DEM with a 20m ground resolution was successfully constructed using a automatic matching procedure.