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지표레이더(GPR) 탐사자료를 이용한 지하공동 분석 시 신뢰도 향상을 위한 영상처리기법의 활용
김보나 ( Bona Kim ),설순지 ( Soon Jee Seol ),변중무 ( Joongmoo Byun ) 한국지구물리·물리탐사학회 2017 지구물리와 물리탐사 Vol.20 No.2
Recently, ground-penetrating radar (GPR) surveys have been actively carried out for precise subsurface void investigation because of the rapid increase of subsidence in urban areas. However, since the interpretation of GPR data was conducted based on the interpreter`s subjective decision after applying only the basic data processing, it can result in reliability problems. In this research, to solve these problems, we analyzed the difference between the events generated from subsurface voids and those of strong diffraction sources such as the buried pipeline by applying the edge detection technique, which is one of image processing technologies. For the analysis, we applied the image processing technology to the GRP field data containing events generated from the cavity or buried pipeline. As a result, the main events by the subsurface void or diffraction source were effectively separated using the edge detection technique. In addition, since subsurface voids associated with the subsidence has a relatively wide scale, it is recorded as a gentle slope event unlike the event caused by the strong diffraction source recorded with a sharp slope. Therefore, the directional analysis of amplitude variation in the image enabled us to effectively separate the events by the subsurface void from those by the diffraction source. Interpretation based on these kinds of objective analysis can improve the reliability. Moreover, if suggested techniques are verified to various GPR field data sets, these approaches can contribute to semiautomatic interpretation of large amount of GPR data.
모서리 반응을 이용한 효과적인 Structure-Oriented Filter-Edge Preserving (SOF-EP) 기법
김보나,변중무,설순지,Kim, Bona,Byun, Joongmoo,Seol, Soon Jee 한국지구물리물리탐사학회 2017 지구물리와 물리탐사 Vol.20 No.3
탄성파 탐사 영상에 적절한 평활화 기법을 적용하게 되면 무작위 잡음이 제거되고 신호의 연속성이 증가되어 보다 정밀한 해석을 할 수 있다. 자료의 특성을 해치지 않으면서 효율적으로 탄성파 탐사자료를 평활화 하기 위해서 최근까지 활발하게 연구 및 사용되고 있는 방법 중 하나가 SOF-EP (Structure-Oriented Filter-Edge Preserving) 기법이다. 이 기법은 자료의 진폭이 큰 곳에서 작은 곳으로 확산되는 원리를 이용하며, 수평층과 같은 연속성이 있는 구조에서는 층을 따라 확산 혹은 평활화가 일어나게 해줌으로써 층 내의 연속성을 증가시키고 무작위 잡음을 제거하는 효과를 가져온다. 또한, 단층과 같은 불연속적인 주요 구조 경계에서의 확산 혹은 평활화를 막기 위하여 연속성 결정 인자를 설정함으로써 평활화 기법의 정밀성을 높일 수 있다. 하지만, 연속성 결정인자를 계산하기 위하여 사용되어 온 구조지향 닮음(structure-oriented semblance) 기법의 경우, 사용하는 필터의 크기나 자료의 양에 따라 많은 시간이 소요되기 때문에 효율성이 떨어지는 한계를 가진다. 이 연구에서는 먼저 SOF-EP 기법을 구현하고, 현장자료에 단계적으로 적용함으로써 그 효용성을 확인하였으며 다음으로 효율적으로 연속성 결정인자를 계산할 수 있는 모서리 반응 기법(corner response method)을 제안 및 적용하여 기존의 방법과 비교하였다. 그 결과 약 6000배 이상 계산 시간을 단축할 수 있음을 확인하였다. To interpret the seismic image precisely, random noises should be suppressed and the continuity of the image should be enhanced by using the appropriate smoothing techniques. Structure-Oriented Filter-Edge Preserving (SOF-EP) technique is one of the methods, that have been actively researched and used until now, to efficiently smooth seismic data while preserving the continuity of signal. This technique is based on the principle that diffusion occurs from large amplitude to small one. In a continuous structure such as a horizontal layer, diffusion or smoothing is operated along the layer, thereby increasing the continuity of layers and eliminating random noise. In addition, diffusion or smoothing across boundaries at discontinuous structures such as faults can be avoided by employing the continuity decision factor. Accordingly, the precision of the smoothing technique can be improved. However, in the case of the structure-oriented semblance technique, which has been used to calculate the continuity factor, it takes lots of time depending on the size of the filter and data. In this study, we first implemented the SOF-EP method and confirmed its effectiveness by applying it step by step to the field data. Next, we proposed and applied the corner response method which can efficiently calculate the continuity decision factor instead of structure-oriented semblance. As a result, we could confirm that the computation time can be reduced by about 6,000 times or more by applying the corner response method.
임신혁,김동규,윤지훈,김보나,방은석,심규민,이상경,오종식,Sin Hyuk Yim,Dongkyu Kim,Ji Hun Yoon,Bona Kim,Eun Seok Bang,Kyu Min Shim,Sangkyung Lee,Jong-shick Oh 한국군사과학기술학회 2023 한국군사과학기술학회지 Vol.26 No.4
Drone based Magnetic Anomaly Detection measure a magnetic anomaly signal from the ferromagnetic target on the ground. We conduct a magnetic anomaly detection with 9 ferromagnetic targets on the ground. By removing the magnetic field measured in the absence of ferromagnetic targets from the experimental value, the magnetic anomaly signal is clearly measured at an altitude of 100 m. We analyze the signal characteristics by the ferromagnetic target through simulation using COMSOL multiphysics. The simulation results are within the GPS error range of the experimental results.
셰일 저류층에서 케로젠, GOR 변화에 따른 속도 변화 및 AVO 반응 분석
최준환 ( Junhwan Choi ),이재욱 ( Jaewook Lee ),변중무 ( Joongmoo Byun ),김보나 ( Bona Kim ),김소영 ( Soyoung Kim ) 한국지구물리·물리탐사학회 2016 지구물리와 물리탐사 Vol.19 No.1
Recently, the studies about rock physics model (RPM) in shale reservoir are widely performed. In shale reservoir, the degree of the maturity can be estimated by kerogen and GOR (Gas-Oil Ratio). The researches on the rock physics model of shale reservoir with the amount of kerogen have been actively carried out but not with GOR. Thus, in this study, we analyzed the changes in seismic velocity and density, and AVO (Amplitude Variation with Offset) response depending on changes in GOR and the amount of kerogen. Since the shale consists of plate-like particles, it has vertical transverse isotropy (VTI). Therefore we estimated the seismic velocity and density by using Backus averaging method and analyzed AVO responses based on these estimated properties. The results of analysis showed that the changes in the velocity with the GOR variation are small but the velocity changes with the variation in kerogen amount are relatively larger. In case, GOR 180 (Litre/Litre) which is boundary between heavy oil and light oil, when volume fraction of kerogen increased from 5% to 35%, the P-wave velocity normal to the layering increased 51%. That is, it helps estimating maturity of kerogen through the velocity. Meanwhile, when rates of oil-gas mixture are large, the effect of GOR variation on the velocity change became larger. In case volume fraction of kerogen is 5%, the P-wave velocity normal to the layering was estimated 1.46 km/s2 in heavy oil (GOR 40) but 1.36 km/s2 in light oil (GOR 300). The AVO responses analysis showed class 4 regardless of the GOR and amount of kerogen because variation of poisson’s ratio is small. Therefore, shale reservoir has possibility to have class 4.
Triple antibiotics와 관련한 치아 변색의 예방
김보나,송민주,신수정,박정원 大韓齒科保存學會 2012 Restorative Dentistry & Endodontics Vol.37 No.2
Regenerative endodontics has a potential to heal a partially neecrotic pulp, which can be beneficial for the continued root development and strengthening of immature teeth. For this purpose, triple antibiotic mixture of ciprofloxacin, metronidazole, and minocycline was recommended as intracanal medicament in an attempt to disinfect the root canal system for revascularization of a tooth with a necrotic pulp. However, discoloration of the tooth was reported after applying this. This case shows the idea for preventing the tooth discoloration using a delivery syringe (SW-0-01, Shinwoo dental) to avoid the contact between the clinical crown and the antibiotics.