• 한국대기환경학회지
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• 제23권4호
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• pp.449-456
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• 2007

Dispersion coefficient preprocessing schemes have been examined to improve plume dispersion model performance in complex coastal areas. The performances of various schemes for constructing the sigma correction order were evaluated through estimations of statistical measures, such as bias, gross error, R, FB, NMSE, within FAC2, MG, VG, IOA, UAPC and MRE. This was undertaken for the results of dispersion modeling, which applied each scheme. Environmental factors such as sampling time, surface roughness, plume rising, plume height and terrain rolling were considered in this study. Gaussian plume dispersion model was used to calculate 1 hr $SO_2$ concentration 4 km downwind from a power plant in Boryeung coastal area. Here, measured data for January to December of 2002 were obtained so that modelling results could be compared. To compare the performances between various schemes, integrated scores of statistical measures were obtained by giving weights for each measure and then summing each score. This was done because each statistical measure has its own function and criteria; as a result, no measure can be taken as a sole index indicative of the performance level for each modeling scheme. The best preprocessing scheme was discerned using the step-wise method. The most significant factor influencing the magnitude of real dispersion coefficients appeared to be sampling time. A second significant factor appeared to be surface roughness, with the rolling terrain being the least significant for elevated sources in a gently rolling terrain. The best sequence of correcting the sigma from P-G scheme was found to be the combination of (1) sampling time, (2) surface roughness, (3) plume rising, (4) plume height, and (5) terrain rolling.

• 한국측량학회지
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• 제33권6호
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• pp.475-483
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• 2015

This study examined the feasibility of using an automatic lens distortion correction (ALDC) camera as the payload for a photogrammetric unmanned aerial vehicle (UAV) system. First, lens distortion for the interior orientation (IO) parameters was estimated. Although previous studies have largely ignored decentering distortion, this study revealed that more than 50% of the distortion of the ALDC camera was caused by decentering distortion. Second, we compared the accuracy of bundle adjustment for camera calibration using three image types: raw imagery without the ALDC option; imagery corrected using lens profiles; and imagery with the ALDC option. The results of image triangulation, the digital terrain model (DTM), and the orthoimage using the IO parameters for the ALDC camera were similar to or slightly better than the results using self-calibration. These results confirm that the ALDC camera can be used in a photogrammetric UAV system using only self-calibration.

• 대한원격탐사학회지
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• 제14권1호
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• pp.69-82
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• 1998

SAR 영상은 기존의 전자광학적 센서가 갖고 있는 자료취득의 제한을 극복하고, 광학적 센서와 상호보완되는 정보를 제공한다. 하지만 SAR 센서와 지면의 기하학적 특성으로 인하여 영상에 내재되어 있는 다양한 기하학적 왜곡을 제거할 필요가 있다. SAR 영상의 기하보정 방법으로 여러 가지 다양한 기법이 소개되고 있지만, SAR 영상을 정확하게 기하보정하는 것은 쉽지 않다. 특히 Radarsat 위성에 채택되고 있는 "International" 타원체와 국내의 "Bessel" 타원체간의 변환관계가 확립되지 않아 기하보정에 어려움이 있다. 보편적으로 많이 이용되는 모의영상을 이용한 기하보정 방법과 공선조건식을 응용한 기하보정 방법에는 수치표고모형이 이용된다. 본 연구에서는 기하보정에 사용되는 방법간의 장점과 단점을 파악하고 국내에 적용될 수 있는 방법을 찾아냈다.

• 자원환경지질
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• 제28권5호
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• pp.469-480
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• 1995

Gravity and magnetic surveys were carried out to investigate the three-dimensional configuration and characteristics of the landfills at Nanjido waste disposal site. For terrain correction and three-dimensional density inversion of gravity data an algorithm, which calculates the gravity effect of a three-dimensional body by using the solid angle method, is developed. This algorithm has been proved to give more accurate terrain correction values for the small survey area having varied topography like Nanjido site as compared with widely used methods such as Hammer's method and multiquadric equation method. Density inversion of gravity anomaly data gives very useful information about the lateral and vertical variation of the landfills, which can be used to discriminate the kinds of wastes. The average density of filled materials appears to be $1.7\;g/cm^3$ which is much higher than the value $(0.8\;g/cm^3)$ estimated by Seoul City. The lateral variation of density shows high correlation with the pattern of ongoing depression of the landfills. The northern region of the landfill no. 1, which shows low density and high depression, is closely associated with the industrial waste and sludge filled area. The magnetic anomaly data provide information about relative concentration of magnetic materials, which is also very useful to investigate characteristics of the fills. Several high positive anomaly regions on the reduced-to-pole magnetic anomaly map are appeared to be associated with the industrial waste fills, but certain industrial waste fills show low negative anomalies. This kind of magnetic information can be used in selecting drilling locations over landfills away from buried metal products during the stabilization process.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2002년도 Proceedings of International Symposium on Remote Sensing
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• pp.708-708
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• 2002

Recent developments in sensor technologies have provided remotely sensed data with very high spatial resolution. In order to fully utilize the potential of high resolution images, new image classification strategies are necessary. Unfortunately, the high resolution images increase the spectral within-field variability, and the classification accuracy of traditional methods based on pixel-based classification algorithms such as Maximum-Likelihood method may be decreased (Schiewe 2001). Recent development in Object Oriented Classification based on image segmentation algorithms can be used for the classification of forest patches on rugged terrain of Korea. The objectives of this paper are as follows. First, to compare the pros and cons of image classification methods based on pixel-based and object oriented classification algorithm for the forest patch classification. Landsat ETM＋ data and IKONOS data will be used for the classification. Second, to investigate ways to increase classification accuracy of forest patches. Supplemental data such as DTM and Forest Type Map of 1:25,000 scale are used for topographic correction and image segmentation. Third, to propose the best classification strategy for forest patch classification in terms of accuracy and data requirement. The research site for this paper is Namhansansung Provincial Park located at the eastern suburb of Seoul Metropolitan City for its diverse forest patch types and data availability. Both Landsat ETM＋ and IKONOS data are used for the classification. Preliminary results can be summarized as follows. First, topographic correction of reflectance is essential for the classification of forest patches on rugged terrain. Second, object oriented classification of IKONOS data enables higher classification accuracy compared to Landsat ETM＋ and pixel-based classification. Third, multi-stage segmentation is very useful to investigate landscape ecological aspect of forest communities of Korea.

• 한국대기환경학회지
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• 제14권3호
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• pp.219-228
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• 1998

In the present investigation, a numerical model developed for the prediction of the wind flow over complex terrain is validated by comparing with the field experiments. For the solution of the Reynolds - Averaged Clavier- stokes equations which are the governing equations of the microscale atmospheric flow, the model is constructed based on the finite-volume formulation and the SIMPLEC pressure-correction algorithm for the hydrodynamic computation. The boundary- fitted coordinate system is employed for the detailed depiction of topography. The boundary conditions and the modified turbulence constants suitable for an atmospheric boundary- layer are applied together with the k- s turbulence model. The full- scale experiments of Cooper's Ridge, Kettles Hill and Askervein Hill are chosen as the validation cases . Comparisons of the mean flow field between the field measurements and the predicted results show good agreement. In the simulation of the wind flow over Askervein Hill , the numerical model predicts the three dimensional flow separation in the downslope of the hill including the blockage effect due to neighboring hills . Such a flow behavior has not been simulated by the theoretical predictions. Therefore, the present model may offer the most accurate prediction of flow behavior in the leeside of the hill among the existing theoretical and numerical predictions.

• 한국콘텐츠학회논문지
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• 제7권9호
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• pp.204-211
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• 2007

본 연구에서는 연구지역을 대상으로 항공사진과 수치지형도를 이용하여 3차원 지형 모델링을 제작하였고 이를 이용하여 가시권 분석과 동아대학교에 대한 Web GIS를 구현하였다. 연구지역은 부산광역시 사하구 하단동 일대를 지정하였으며, 축척 1:20,000의 항공사진과 축척 1:5,000의 수치지형도를 사용하였다. 항공사진은 GCP선정과 영상정합을 통하여 보정된 영상을 추출하고 영상재배열 과정과 정밀미분편위수정을 거쳐 최종 정사보정된 영상을 제작하였다. 그리고 ArcView 프로그램을 이용하여 수치지형도에서 DEM을 생성하였고, 도로 레이어와 건물 레이어를 추출하여 3차원 지형 모델링을 제작함과 동시에 동아대학교에 대한 Web GIS를 구현하였다.

• 한국안전학회지
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• 제33권3호
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• pp.65-70
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• 2018

Terrain data for disaster analysis in hazardous or disaster areas is not only important but also needs to be built quickly. In particular, the introduction of drones is in the early stages of research using drones in a variety of fields such as shooting, analyzing and managing hazardous areas. It is expected that drone will be faster, safer and more effective than existing data collection method in case of small scale disaster hazard area and disaster area where equipment or manpower input is difficult. Therefore, in this study, drone shooting was performed for hazardous areas in mountainous roads located in Samcheok city, Gangwon province, and ground reference points were measured by RTK-GPS. The measured data were converted into DSM (Digital Surface Model) data by coordinate correction using Pix4D postprocessing program and then applied to the analysis of the hazard area of mountainous area. As a result, it was shown that it is effective to identify the risk by using the basic terrain data obtained from the drones.

• 한국지구물리탐사학회:학술대회논문집
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• 한국지구물리탐사학회 2003년도 Proceedings of the international symposium on the fusion technology
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• pp.379-382
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• 2003

In gravity data correction process, mass effect of the upper part of base level is removed with Bouguer density. Usually, Bouguer density is estimated as a mean density in the field area. But, this may causes a serious problem when ore body is in the area. To overcome this problem, we tried to apply a new method mixing up mass corrections and inversion (3DGTI). 3-D Gravity Terrain Inversion (3DGTI) includes information of topography and distribution of Bouguer density. For this method does not remove the mass effect above base level, it is no longer useless to use Bouguer density. Numerical model tests have shown that the 3DGIT successfully retrieves the anomalous subsurface density distribution of both surface and deeper layers. Model tests shows that this method shows better results than those of conventional one, especially when main target is ore body. The inversion result well delineates the three-dimensional shape of the intruded granite body and basement.

• Journal of Radiation Protection and Research
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• 제23권4호
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• pp.251-257
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• 1998

국내 원전에 적용하기 위한 기체 방사성 물질 확산 및 피폭 평가 코드를 개발하였다. 정상 운전에 의한 기체 방사성 물질 확산 및 피폭 평가에는 직선 궤도 가우시안 플륨 모델을 사용하는 XOQDOQ 코드가 사용되어 왔다. 본 연구에서는 이 코드의 단점인 발전소 주변 지역에서의 바람 방향의 영향, 산악 지형에 대한 모델, 습식 침적에 대한 개선이 이루어졌다. 현실적인 유효 고도 보정 및 산악 침투 모델을 통해서 산악 지형에 대한 고려를 하였고, 바람 발생 확률 빈도를 수정하여 직선 궤도 모델을 보완하였다. 개발된 코드는 영광원전의 주민피폭선량평가를 위해 채택되었으며, 산악이 많은 우리 나라 다른 발전소에 적용하기 위해 산악지형 입력변경을 통하여 적절히 사용될 수 있을 것이다.