• Proceedings of the Korea Information Processing Society Conference
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• 2009.11a
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• pp.311-312
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• 2009

$A^*$ 알고리즘을 이용한 경로 계획은 이동 로봇이나 게임 유닛이 주어진 환경에서 장애물과 충돌 없이 이동 가능한 경로를 찾는데 많이 사용된다. 그러나 $A^*$ 알고리즘은 출발 지점에서 목적 지점까지의 최단 거리를 갖는 경로를 찾는다. 두 지점 사이에 장애물이 있는 경우, 최단 경로는 보통 두 지점 사이의 장애물의 모서리를 스치는 경로이다. 따라서 로봇이나 게임 유닛이 최단 경로로 이동할 때, 장애물의 모서리에 부딪힐 수 있는 위험성이 커진다. 일반적인 격자 지도의 한 셀은 장애물이 있는 경우의 무한대의 비용과 장애물이 없는 경우의 비용을 갖는다. 본 논문에서는 장애물에 가까울수록 장애물이 없는 경우보다 높은 비용을 갖는 점층적 격자 지도(gradation grid map)를 이용한다. 점층적 격자 지도를 통해 $A^*$ 알고리즘은 장애물 근처의 높은 비용을 갖는 셀을 되도록 통과하지 않는 경로, 즉 보다 안전한 경로를 생성한다.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.13 no.2
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• pp.27-33
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• 2014

This paper proposes a gradation image processing method for the development of a Road Sign Recognition Platform (RReP), which aims to facilitate the rapid and accurate management and surveying of approximately 160,000 road signs installed along the highways, national roadways, and local roads in the cities, districts (gun), and provinces (do) of Korea. RReP is based on GPS(Global Positioning System), IMU(Inertial Measurement Unit), INS(Inertial Navigation System), DMI(Distance Measurement Instrument), and lasers, and uses an imagery information collection/classification module to allow the automatic recognition of signs, the collection of shapes, pole locations, and sign-type data, and the creation of road sign registers, by extracting basic data related to the shape and sign content, and automated database design. Image division and merging, which were applied in this study, produce superior results compared with local binarization method in terms of speed. At the results, larger texts area were found in images, the accuracy of text recognition was improved when images had been gradated. Multi-threshold values of natural scene images are used to improve the extraction rate of texts and figures based on pattern recognition.

• Journal of radiological science and technology
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• v.33 no.2
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• pp.97-107
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• 2010

The objectives of this study is to figure out the unknown image processing methods of commercial CR system. We have implemented the processing curve of each Look up table(LUT) in REGIUS 150 CR system by using virtual digital test pattern method. The characteristic of Dry Imager was measured also. First of all, we have generated the virtual digital test pattern file with binary file editor. This file was used as an input data of CR system (REGIUS 150 CR system, KONICA MINOLTA). The DICOM files which were automatically generated output files by the CR system, were used to figure out the processing curves of each LUT modes (THX, ST, STM, LUM, BONE, LIN). The gradation curves of Dry Imager were also measured to figure out the characteristics of hard copy image. According to the results of each parameters, we identified the characteristics of image processing parameter in CR system. The processing curves which were measured by this proposed method showed the characteristics of CR system. And we found the linearity of Dry Imager in the middle area of processing curves. With these results, we found that the relationships between the curves and each parameters. The G value is related to the slope and the S value is related to the shift in x-axis of processing curves. In conclusion, the image processing method of the each commercial CR systems are different, and they are concealed. This proposed method which uses virtual digital test pattern can measure the characteristics of parameters for the image processing patterns in the CR system. We expect that the proposed method is useful to analogize the image processing means not only for this CR system, but also for the other commercial CR systems.

• Proceedings of the Korea Information Processing Society Conference
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• 2000.10b
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• pp.907-910
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• 2000

만화 영상은 대체적으로 단순하면서도 일정한 기울기(Gradation)를 가지는 영역이 많이 존재한다. 본 논문에서는 이러한 만화 영상의 특징을 고려해서 상보 쿼드트리를 이용한 효율적인 압축방법을 제안하고자 한다. 제안한 방법에서 상위마디의 색상은 하위 마디 중에서 가장 많은 부분을 차지하는 색상이 되며 각각의 마디는 형태 부호와 색상 부호 또는 형태 부호와 기울기 값으로 나타내어진다. 기울기를 가지는 영역이 많이 존재하는 만화 영상에서 제안한 방법은 기존의 다른 압축 방법보다 비트수를 줄일 수 있고, 무손실 점진적 전송도 가능하다.

• Proceedings of the Korea Information Processing Society Conference
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• 2008.11a
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• pp.1510-1512
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• 2008

사이버 공간에서 미래 최대 위협 중 하나로 인식되고 있는 봇넷의 공격이 점차 증가함에 따라, 봇넷 공격에 기반한 피해가 증가하고 있으며, 금전적인 피해 유발로 그 심각성이 점차 증대되고 있는 실정이다. 특히, 봇넷은 좀비 PC를 활용하는 측면에서 제 2차, 3차 피해가 우려되고 있다. 따라서 봇넷의 탐지를 1차적으로 끝나는 것이 아니라 지속적인 관찰과 관리를 통해 변종 봇넷을 탐지 하고 이에 기반한 악성행위를 탐지하는 것이 무엇보다도 중요하다. 따라서 본 논문에서는 이러한 봇넷을 능동적으로 탐지하기 위한 능동형 봇넷 탐지 및 관리를 위한 단계적 마이닝 프로세스를 제안하고 기존 탐지 알고리즘과의 비교 평가를 하여 향후 적용을 위한 고려사항들을 논의 하고자 한다.

• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.930-932
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• 2003

For this study we used a CCD video camera to capture the pavement image information via the computer. During investigation processing, the CCD video camera captured 10${\sim}$30 images per second. If the vehicle velocity is too fast, the collected images will be duplicated and if the velocity is too slow there will be a gapped between images. Therefore, in order to control the efficiency of the image grabber we should add accessory tools such as the Differential Global Positioning System (DGPS) and odometer. Furthermore, Kalman Filtering can also solve these problems. After the CCD video camera captured the pavement images, we used the Least-Squares method to eliminate images of gradation which have non-uniform surfaces due to the illumination at night. The Fuzzy Entropy method calculates images of threshold segments and creates binary images. Finally, the Object Labeling algorithm finds objects that are cracks or noises from the binary image based on volume pixels of the object. We used these algorithms and tested them, also providing some discussion and suggestions.

• Advances in aircraft and spacecraft science
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• v.9 no.6
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• pp.507-523
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• 2022

This study is aimed to accurately predict the vibration response of two types of functionally graded sandwich plates, one with FGM core and another with FGM face sheets. The gradation in FGM layer is quantified by exponential method. An efficient zig-zag theory is used and the zigzag impacts are established via a linear unit Heaviside step function. The present theory fulfills interlaminar transverse stress continuity at the interface and zero condition at the top and bottom surfaces of the plate for transverse shear stresses. Nine-noded C-0 FE having 8DOF/node is utilized throughout analysis. The present model is free from the obligation of any penalty function or post-processing technique and hence is computationally efficient. Numerical results have been presented on the free vibration behavior of sandwich FGM for different end conditions, lamination schemes and layer orientations. The applicability of present model is confirmed by comparing with published results. Several new results are also specified, which will serve as the benchmark for future studies.

• Transactions of Materials Processing
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• v.23 no.5
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• pp.303-310
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• 2014

Functionally graded properties are characterized by the gradual variation in composition and structure through the volume of the material, resulting in corresponding gradation in properties of the material. Direct laser melting (DLM) is a prototyping process whereby a 3-D part is built layer-wise by melting metal powder with laser scanning. Studies have been performed on the functionally graded properties induced by direct laser melting of compositionally selected metallic powders. For the current study, quadrangle structures were fabricated by DLM using Fe-Ni-Cr powders having variable compositions. Hardness and EDX analysis were conducted on cross-sections of the fabricated structure to characterize the properties. From the analysis, it is shown that functionally graded properties can be successfully obtained by DLM of selected metallic powders with varying compositions.

• International Journal of Concrete Structures and Materials
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• v.6 no.4
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• pp.247-250
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• 2012

Composites are somewhat more difficult to model than an isotropic material such as iron or steel due to the fact that each layer may have different orthotropic material properties. In finite element literature the asphalt mixes are represented by using rectangular meshes, not the actual picture of their cross-sections. Asphalt aggregate size and distribution in the asphalt concrete sample, aggregate shape, and fractured surface effects are ignored. In this research, the actual image of the sample including all these effects were directly considered in the finite element. The samples, were cut into cross-sections and were scanned. The image-processing toolbox of Labview was utilized in obtaining the rectangular gray images of the scanned images. In the rectangular sample the aggregates were white and the asphalt binders were black. The grayscale images were converted by LABVIEW into the format required by ANSYS as an input file, with the same dimensions. The nodes at the bottom of the model were constrained in both x and y directions. Left and right edges were symmetry and top was free. Certain amount of pressure was applied along the top surface to simulate the tire pressure.

• The Journal of the Korea Contents Association
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• v.12 no.1
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• pp.1-8
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• 2012

In this paper, a method of determining the optimal threshold in image binarization for the marker recognition is suggested to resolve the problem that the performances of marker recognition are quite different according to the changes of indoor lighting. The suggested method determines the optimal threshold by considering the average brightness, the standard deviation and the maximum deviation of video image under the various indoor lighting circumstances, such as bright light, dim light, and shadow by unspecified obstacles. In particular, the recognition under the gradation lighting by shadow is improved by applying the weighted value that depends on the brightness of image. The suggested method is experimented to process $720{\times}480$ resolution video images under the various lighting environments, and it shows the fast and high performance, which is suitable for mobile indoor navigation.