• Proceedings of the KSRS Conference
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• 2009.03a
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• pp.207-212
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• 2009

고해상도 위성영상이 갖는 공간 객체의 복잡성과 다양성에 의해 기존 중 저해상도 영상에서 사용하던 분류 방식을 고해상도 영상에 그대로 적용하기에는 한계가 있다. 이러한 문제를 극복하기 위하여 영상은 공간적인 특성을 추가적으로 추출하여 분광정보와 결합하여 분류를 수행하는 방식의 연구가 진행되고 있다. 본 연구의 목적은 고해상도 영상의 분류정확도를 개선하기 위하여 새로운 공간 개체(spatial feature)인 SSI(Shape-Size Index)를 제안하는데 있다. SSI는 영역 확장(Region Growing) 기반의 영상 분할(Image Segmentation)을 수행한 후, 객체 내에 객체의 크기와 모양에 대한 고려를 모두 할 수 있는 공간 속성값을 할당하여 공간정보를 추출한다. 추출된 공간정보를 고해강도 영상의 다중분광 밴드와 결합하여 Support Vector Machine(SVM)을 이용한 분류를 수행하였다. 실험 결과, 제안한 기법의 분류 결과가 분광밴드만을 이용하여 분류를 수행한 결과뿐만 아니라 기존의 공간 개체 추출방식인 GLCM, PSI 기법을 이용한 분류 결과에 비해 높은 분류정확도를 도출함을 알 수 있었다.

• Korean Journal of Remote Sensing
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• v.39 no.3
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• pp.283-295
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• 2023

With the development of sensor and satellite technology, numerous high-resolution and multi-spectral satellite images have been available. Due to their wavelength-dependent reflection, transmission, and scattering characteristics, multi-spectral satellite images can provide complementary information for earth observation. In particular, the short-wave infrared (SWIR) band can penetrate certain types of atmospheric aerosols from the benefit of the reduced Rayleigh scattering effect, which allows for a clearer view and more detailed information to be captured from hazed surfaces compared to the visible band. In this study, we proposed a multi-resolution transform-based image fusion method to combine visible and SWIR satellite images. The purpose of the fusion method is to generate a single integrated image that incorporates complementary information such as detailed background information from the visible band and land cover information in the haze region from the SWIR band. For this purpose, this study applied the Laplacian pyramid-based multi-resolution transform method, which is a representative image decomposition approach for image fusion. Additionally, we modified the multiresolution fusion method by combining a haze-guided weight map based on the prior knowledge that SWIR bands contain more information in pixels from the haze region. The proposed method was validated using very high-resolution satellite images from Worldview-3, containing multi-spectral visible and SWIR bands. The experimental data including hazed areas with limited visibility caused by smoke from wildfires was utilized to validate the penetration properties of the proposed fusion method. Both quantitative and visual evaluations were conducted using image quality assessment indices. The results showed that the bright features from the SWIR bands in the hazed areas were successfully fused into the integrated feature maps without any loss of detailed information from the visible bands.

• 한국지형공간정보학회:학술대회논문집
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• 1993.10a
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• pp.101-106
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• 1993

본 연구의 목적은 토지자원의 유효한 개발과 관리를 위해 원격탐사 자료 및 지상자료를 이용하여 토지 이용의 예측 모형을 정립하고 실제로 제주도 지역에 적용하여 그 실증을 거치는 것이었다. 본 토형은 계절분석(multi-date processing) 및 다중분석 (multi-file processing)기법을 채택하고 Markov의 확률 이전 계산법 및 판별 함수 (discriminant function) 계산법으로부터 합성 출현된 공간적/시간적 토지이용 투영방법을 채택하였다. 판별 함수 계산법은 토지이용 변화상의 최다 경향치를 산출하기 위해 제주도 경관 평면(landscape plane) 전지역의 각 화소(pixel)에 적용되고, 확률 이전 계산법은 특정 미래 시간 간극상에서 상이한 토지이용으로 변화하는 이들 화소의 수량을 결정한다. 본 합성 모형은 이렇게 토지이용 변화성(정성적)과 그 화소의 수량(정량적)을 결합하여 경관 평면상에서 미래의 토지이용 예측을 가능케하는 것이다.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2007.11a
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• pp.167-174
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• 2007

This study proposes a practical and realistic method to establish an optimal lifetime maintenance strategy for deteriorating bridges by considering the life-cycle performance as well as the life-cycle cost. The proposed method offers a set of optimal tradeoff maintenance scenarios among other conflicting objectives, such as minimizing cost and maximizing performance. A genetic algorithm is used to generate a set of maintenance scenarios that is a multi-objective combinatorial optimization problem related to the and the life-cycle cost and performance as separate objective functions. A computer program, which generates optimal maintenance scenarios, was developed based on the proposed method. The subordinate relation between bridge members has been considered to decide optimal maintenance sequence. The developed program has been used to present a procedure for finding an optimal maintenance scenario for steel-girder bridges on the Korean National Road. Through this bridge maintenance scenario analysis, it is expected that the developed method and program can be effectively used to allow bridge managers an optimal maintenance strategy satisfying various constraints and requirements.

• Journal of the Korean Geotechnical Society
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• v.25 no.9
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• pp.93-100
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• 2009

A core procedure of the direct search method used in this study is optimizing a difference between objective function and real displacement and correcting unknown variables. Because the research procedure comes from back-analyzing of the unknown variable of each layer, back-analyzing results need an additional optimization to minimize interferential effects of unknown variables. Therefore, the direct search method Is used to obtain optimized solutions without a partial differentiation of an objective function. The object of this research is developing the back analysis technique for multi-unknown variables by modeling the soil including underground structure Into upper and lower layer. In order to minimize interferent errors, repeated back analysis is performed and applicability on the real tunnel is examined. Consequently, the multi-layer analysis model is more precise in describing the real behavior of underground structure. It shows the validity of back analysis far multi-layer model which is the understructure placed on multi-layer boundaries.

• Journal of Advanced Navigation Technology
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• v.14 no.1
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• pp.49-56
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• 2010

Severe energy constraints and the low power consumption require the significance of the energy efficient error control mechanisms in wireless sensor network (WSN). In this paper, an automatic repeat request (ARQ) methodology for the analysis of error control schemes in WSN is presented such that the effects of packet length, the modulation scheme and the interference effect of the wireless channel are investigated. Moreover, an analyis of ARQ error control is provided by considering two major architectures for wireless sensor network, i.e., Mica2 and MicaZ sensor nodes. And the throughput performance of WSN with asynchronous FSK signal and DSSS-OQPSK signal with selective repeat ARQ scheme are analyzed in multiple interference environment, and the probability of receiving a correct bit and packet from target node to sink node is evaluated as a function of the channel parameter, the number of wireless sensor node, and the spreading factor.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.6A
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• pp.1023-1032
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• 2006

In this paper, a new method for the bridge maintenance is proposed to overcome the limit of the existing methods and to implement the preventive bridge maintenance system. The proposed method can establish the lifetime optimum maintenance strategy of the deteriorating bridges considering the life-cycle performance as well as the life-cycle cost. The lifetime performance of the deteriorating bridges is evaluated by the safety index based on the structural reliability and the condition index detailing the condition state. The life-cycle cost is estimated by considering not only the direct maintenance cost but also the user and failure cost. The genetic algorithm is applied to generate a set of maintenance scenarios which is the multi-objective combinatorial optimization problem related to the life-cycle cost and performance. The study examined the proposed method by establishing a maintenance strategy for the existing bridge and its advantages. The result shows that the proposed method can be effectively applied to deciding the bridge maintenance strategy.

• Journal of Korean Society of Transportation
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• v.22 no.5
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• pp.123-137
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• 2004

The study on traffic assignment is actively being performed which reflect networks status using time. Its background is increasing social needs to use traffic assignment models in not only hardware area of road network plan but also software area of traffic management or control. In addition, multi-class traffic assignment model is receiving study in order to fill a gap between theory and practice of traffic assignment model. This model is made up of two, one of which is multi-driver class and the other multi-vehicle class. The latter is the more realistic because it can be combined with dynamic model. On this background, this study is to build multidynamic model combining the above-mentioned two areas. This has been a theoretic pillar of ITS in which dynamic user equilibrium assignment model is now made an issue, therefore more realistic dynamic model is expected to be built by combining it with multi-class model. In case of multi-vehicle, FIFO would be violated which is necessary to build the dynamic assignment model. This means that it is impossible to build multi-vehicle dynamic model with the existing dynamic assignment modelling method built under the conditions of FIFO. This study builds dynamic network model which could relieve the FIFO conditions. At the same time, simulation method, one of the existing network loading method, is modified to be applied to this study. Also, as a solution(algorithm) area, time dependent shortest path algorithm which has been modified from existing shortest path algorithm and the existing MSA modified algorithm are built. The convergence of the algorithm is examined which is built by calculating dynamic user equilibrium solution adopting the model and algorithm and grid network.

• Korean Journal of Remote Sensing
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• v.30 no.1
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• pp.25-36
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• 2014

Multispectral image classification of individual tree species is often difficult because of the spectral similarity among species. In this study, we attempted to analyze the suitability of hyperspectral image to classify coniferous tree species. Several image sets and classification methods were applied and the classification results were compared with the ones from multispectral image. Two airborne hyperspectral images (AISA, CASI) were obtained over the study area in the Gwangneung National Forest. For the comparison, ETM+ multispectral image was simulated using hyperspectral images as to have lower spectral resolution. We also used the transformed hyperspectral data to reduce the data volume for the classification. Three supervised classification schemes (SAM, SVM, MLC) were applied to thirteen image sets. In overall, hyperspectral image provides higher accuracies than multispectral image to discriminate coniferous species. AISA-dual image, which include additional SWIR spectral bands, shows the best result as compared with other hyperspectral images that include only visible and NIR bands. Furthermore, MNF transformed hyperspectral image provided higher classification accuracies than the full-band and other band reduced data. Among three classifiers, MLC showed higher classification accuracy than SAM and SVM classifiers.

• Nuclear Medicine and Molecular Imaging
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• v.42 no.1
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• pp.52-60
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• 2008

Purpose: To establish the methods for sinogram formation and correction in order to appropriately apply the filtered backprojection (FBP) reconstruction algorithm to the data acquired using PET scanner with multiple scintillation crystal layers. Materials and Methods: Formation for raw PET data storage and conversion methods from listmode data to histogram and sinogram were optimized. To solve the various problems occurred while the raw histogram was converted into sinogram, optimal sampling strategy and sampling efficiency correction method were investigated. Gap compensation methods that is unique in this system were also investigated. All the sinogram data were reconstructed using 20 filtered backprojection algorithm and compared to estimate the improvements by the correction algorithms. Results: Optimal radial sampling interval and number of angular samples in terms of the sampling theorem and sampling efficiency correction algorithm were pitch/2 and 120, respectively. By applying the sampling efficiency correction and gap compensation, artifacts and background noise on the reconstructed image could be reduced. Conclusion: Conversion method from the histogram to sinogram was investigated for the FBP reconstruction of data acquired using multiple scintillation crystal layers. This method will be useful for the fast 20 reconstruction of multiple crystal layer PET data.