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김상완 대한원격탐사학회 2018 大韓遠隔探査學會誌 Vol.34 No.6
For TOPS InSAR processing, high-precision image co-registration is required. We propose an image co-registration method suitable for the TOPS mode by comparing the performance of cross correlation method, the geometric co-registration and the enhanced spectral diversity (ESD) matching algorithm based on the spectral diversity (SD) on the Sentinel-1 TOPS mode image. Using 23 pairs of interferometric pairs generated from 25 Sentinel-1 TOPS images, we applied the cross correlation (CC), geometric correction with only orbit information (GC1), geometric correction combined with iterative cross-correlation (GC2, GC3, GC4), and ESD iteration (ESD_GC, ESD_1, ESD_2). The mean of coregistration errors in azimuth direction by cross correlation and geometric matching are 0.0041 pixels and 0.0016 pixels, respectively. Although the ESD method shows the most accurate result with the error of less than 0.0005 pixels, the error of geometric co-registration is reduced to 0.001 pixels by repetition through additional cross correlation matching between the reference and resampled slave image. The ESD method is not applicable when the coherence of the burst overlap areas is low. Therefore, the geometric co-registration method through iterative processing is a suitable alternative for time series analysis using multiple SAR data or generating interferogram with long time intervals. TOPS InSAR 처리를 위해서는 고정밀도의 영상정합이 요구된다. Sentinel-1 TOPS 모드영상에 교차상관영상정합, 기하정합, Spectral Diversity 정합에 기반 한 Enhanced Spectral Diversity 정합 알고리즘 성능 비교분석을 통해 TOPS모드에 적합한 영상정합 방법을 제시하고자 한다. 25개의 Sentinel-1 TOPS 영상으로부터 생성된 23개의 간섭쌍을 이용하여, 교차상관정합(CC), 기하보정(GC1), 기하보정 후 교차상관정합(GC2, GC3, GC4) 그리고 ESD를 이용한 정합(ESD_GC, ESD_1, ESD_2) 총 8가지 방법을 적용하였다. 교차상관정합과 기하정합에 따른 azimuth 방향 정합오차를 평균한 결과는 각각 0.0041 화소, 0.0016 화소이다. 비록 ESD 방법은 azimuth 정합오차가 0.0005 화소 이하로 가장 정확한 결과를 보이지만, 기하정합 결과는 추가적인 교차상관정합을 통한 반복 과정을 통해 0.001 화소 정도로 오차가 감소하였다. ESD 방법은 burst 중첩지역의 긴밀도가 낮은 경우 적용이 불가능하다. 따라서 반복 적용을 통한 기하정합 방법은 다수의 SAR 자료를 이용한 시계열 분석 또는 긴 시간간격을 갖는 간섭도 생성을 위해서 적합한 대안이 된다.
Antibacterial effect of urushiol on E. faecalis as a root canal irrigant
김상완,신동훈 대한치과보존학회 2017 Restorative Dentistry & Endodontics Vol.42 No.1
Objectives: The purpose of this study was to compare the antibacterial activity of urushiol against Enterococcus faecalis (E. faecalis) to that of NaOCl. Materials and Methods: The canals of thirty two single rooted human teeth were instrumented with Ni-Ti files (ProTaper Next X1, X2, X3, Dentsply). A pure culture of E. faecalis ATCC 19433 was prepared in sterile brain heart infusion (BHI) broth. The teeth were submerged in the suspension of E. faecalis and were incubated at 37°C for 7 days to allow biofilm formation. The teeth were randomly divided into three experimental groups according to the irrigant used, and a negative control group where no irrigant was used (n = 8). Group 1 used physiologic normal saline, group 2 used 6% NaOCl, and group 3 used 10 wt% urushiol solution. After canal irrigation, each sample was collected by the sequential placement of 2 sterile paper points (ProTaper NEXT paper points, size X3, Dentsply). Ten-fold serial dilutions on each vials, and 100 μL were cultured on a BHI agar plate for 8 hours, and colony forming unit (CFU) analysis was done. The data were statistically analyzed using Kruskal-Wallis and Mann-whitney U tests. Results: Saline group exhibited no difference in the CFU counts with control group, while NaOCl and urushiol groups showed significantly less CFU counts than saline and control groups (p < 0.05). Conclusions: The result of this study suggests 10% urushiol and 6% NaOCl solution had powerful antibacterial activity against E. faecalis when they were used as root canal irrigants.
연안여객선 해양사고 분석과 안전관리 방안: 고속여객선 충돌사고를 중심으로
김상완,정창현,박장호 한국해양경찰학회 2020 한국해양경찰학회보 Vol.10 No.2
After a large marine accident of passenger ship in 2014, the system improvement includes the introduction of the maritime safety supervisor system and safety management officer system, and the change from Korea Shipping Association to Korea Maritime Transportation Safety Authority belonging to the passenger ship safety inspector. Marine accidents have been decreased in recent five years through improving the government’s legal system. However, four(4) times of collision accidents for high speed craft were consecutively occurred in Mokpo in 2017, 2018. The passenger ships safety management system for high speed craft are reviewed, and improvement measures are prepared to prevent them from marine accidents. At the first, the current level of our safety management for the passenger ships are grasped. The second, the high-speed passenger ship accident is analyzed using the Fish Bone Analysis method, and collision risk factors are selected among maritime risk factors identified by modelling of Fish Bone Analysis Method. As a result of applying the improvement measures for each factor to the field during about two(2) years, a similar marine accident have not happened. Furthermore, the improvement measures are proposed to be done continuously in the future because collision accidents on high speed craft may cause a lot of personal injury and death. Finally, for the sake of safety operation for the passenger ships, s afety consciousness and safety culture shall be improved together. 2014년 대형 여객선 해양사고 발생을 계기로 해사안전감독관제도와 안전관리책임자제도가 도입되었고 운항관리자의 소속이 조합에서 공공기관으로 변경되었다. 지난5년 동안 정부의 법령·제도개선을 통해 해양사고가 감소하고 있는 추세이나 2017년과 2018년 목포지역에서 연속적으로 4건의 고속여객선 충돌사고가 발생하여 여객선분야의 안전관리 수준 파악과 안전관리 개선방안 제시가 요구되었다. 본 연구에서는Fish Bone 분석기법을 사용하여 고속여객선 해양사고 원인을 고찰하고 개선방안을도출하였다. 고속여객선은 고도의 안전관리가 필요하며 규제 위주의 안전관리에서교육·훈련을 통한 자율적인 안전관리가 병행되어야 하는 것으로 나타났다. 브레인스토밍을 통한 고속여객선 사고의 원인을 파악하고 직·간접인 해사안전 저해요소를 파악하였다. 또한 기기의 신뢰성 향상, 운항관리규정의 보완 그리고 선장 및 항해사에대한 레이더 교육을 실시하였다. 그러한 개선사항을 2년여 동안 여객선 안전관리 현장에 적용한 결과 고속여객선에서 충돌사고가 단 한 건도 발생하지 않아 그 효과가입증되었다. 고속여객선에서의 충돌사고는 많은 인명손상을 초래할 수 있으므로 이를 예방하기 위해서는 지속적인 안전관리업무 수행과 안전의식 및 안전문화 향상이요구되며, 이를 통해서 여객선 안전운항이 확보될 것이다.