• Radiation Oncology Journal
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• v.13 no.4
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• pp.391-396
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• 1995

Purpose : The Conformal Radiation Therapy has bee widely used under favour of development of computer technologies. The delivery of a large number of static radiation fields are being necessary for the conformal irradiation. In this paper we investigate dosimetric characteristics on penumbra regions of a multileaf collimator(MLC), and compare to those of lead alloy block for the optimal use of the system in 3-D conformal radiotherapy. Materials and Methods : The measurement of penumbra by MLC or lead alloy block was performed with 6 or 10 MV X-rays. The film was positioned at a dmax depth and 10 cm depth, and its optical density was determined using a scanning videodensitometer. The effective penumbra, the distance from $80{\%}$ to $20{\%}$ isodose lines and $90{\%}$ to $10{\%}$ were analyzed as a function of the angle between the direction of leaf motion and the edge defined by leaves. Results : Increasing MLC angle ($0-75^{\circ}$) was observed with increasing the penumbra widths and the scalloping effect. There was no definite differences of penumbra width from $80{\%}$ to $20{\%}$ isodose lines, while being the small increase of penumbra width from $90{\%}$ to $10{\%}$ isodose line varing the depth and energy. The effective penumbra width of lead alloy block are agree resonably with those of MLC within 4.8mm. Conclusion : The comparative qualitative study of the penumbra between MLC and lead alloy block demonstrate the clinical acceptability and suitability of the multileaf collimator for 3-D conformal radiotherapy.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.37 no.4
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• pp.11-19
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• 2000

Real-time extraction of traffic information such as the number of vehicles passing, speed, road-occupancy rate, distance between vehicles, and vehicle types from the traffic scenes acquired from the camera on the road, is a core component of the intelligent transportation system(lTS) We present a scheme of extracting the traffic informations based on the spatio-temporal image analysis, which is robust to the variation of weather conditions and the shades. The images of two detection regions for each traffic lane are classified into one of the three categories: the road, the vehicle, and the shade, using the statistical and structural features Quantitative traffic informations are retrieved by analysing the two spatio-temporal images. Since only the local images of detection regions are processed, the real-time operation of more than 30 frames per second is realized while ensuring the detection performance robust to the operating condition.

• Journal of the Korea Society of Computer and Information
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• v.15 no.2
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• pp.41-46
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• 2010

In this paper, we propose a detection method of reduced computational complexity aimed at separating the moving objects from the background in a generic video sequence. In generally, indoor environments, it is difficult to accurately detect the object because environmental factors, such as lighting changes, shadows, reflections on the floor. First, the background image to detect an object is created. If an object exists in video, on a previously created background images for similarity comparison between the current input image and to detect objects through several operations to generate a mixture image. Mixed-use video and video inputs to detect objects. To complement the objects detected through the labeling process to remove noise components and then apply the technique of morphology complements the object area. Environment variable such as, lighting changes and shadows, to the strength of the object is detected. In this paper, we proposed that environmental factors, such as lighting changes, shadows, reflections on the floor, including the system uses mixture images. Therefore, the existing system more effectively than the object region is detected.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.6B
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• pp.1191-1202
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• 1999

We propose an efficient vehicle detection and classification algorithm for an electronic toll collection using the feature which is robust to abrupt intensity change between consecutive frames. The local correlation coefficient between wavelet transformed input and reference images is used as such a feature, which takes advantage of textural similarity. The usefulness of the proposed feature is analyzed qualitatively by comparing the feature with the local variance of a difference image, and is verified by measuring the improvements in the separability of vehicle from shadowy or shadowless road for a real test image. Experimental results from field tests show that the proposed vehicle detection and classification algorithm performs well even under abrupt intensity change due to the characteristics of sensor and occurrence of shadow.

• Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
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• 2008.06a
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• pp.202-205
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• 2008

건물이 밀집된 도심지역을 촬영한 두 시기 항공영상에 화소기반 변화탐지 기법인 영상대차(Image Differencing), 영상중첩 분석(Image Overlay)기법을 적용하여 넓은 대도심지역의 효율적인 변화탐지 가능성을 살펴보았다. 영상대차(Image Differencing) 기법은 알고리즘이 간단하고 정량적인 분석이 가능한 결과를 얻을 수 있다는 장점이 있으나 고층건물밀집지역을 보여주고 있는 고해상도 항공영상의 적용과정에서는 폐색영역, 그림자 등으로 인해 정확한 변화탐지 결과를 보여주지 못했다. 영상중첩 분석(Image Overlay)기법은 한 번에 두 개 또는 세 개의 영상을 비교 분석할 수 있다는 장점이 있으나 직관적인 분석만을 제공하고 정량적인 분석이 불가능하였다. 현재의 화소기반 영상변화탐지 기술수준으로는 고해상도 공간영상에 대한 신뢰도 높은 변화탐지 분석결과를 얻을 수 없다는 것을 확인하였다.

• Journal of the Microelectronics and Packaging Society
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• v.26 no.4
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• pp.141-148
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• 2019

Electronic substrates used in a mobile device is composed of various materials, and when the temperature is changed during manufacturing or operating, thermal deformation and stress concentration occur due to the difference in thermal expansion coefficient of each material. The shadow moiré technique is a non-contact optical method that measures shape or out-of-plane displacement over the entire area, but it is necessary to overcome the Talbot effect for high sensitivity applications. In this paper, LED light sources of various wavelengths was used to overcome the Talbot effect caused in the shadow moiré technique. By using the phase shift method, an experimental method to retain the measurement sensitivity within 10 ㎛/fringe was proposed and evaluated, and this method is applied to the thermal deformation measurement of the mobile electronic substrate. In the case of using white light, there were several areas that could not be measured due to the Talbot effect, but in the case of using blue LED light, it was shown that a precise moiré pattern with a sensitivity of 6.25 ㎛/fringe could be obtained in most areas.

• Journal of KIISE:Software and Applications
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• v.31 no.11
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• pp.1534-1542
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• 2004

A novel vision-based scheme of extracting real-time traffic information parameters is presented. The method is based on a region classification followed by a spatio-temporal image analysis. The detection region images for each traffic lane are classified into one of the three categories: the road, the vehicle, and the shadow, using statistical and structural features. Misclassification in a frame is corrected by using temporally correlated features of vehicles in the spatio-temporal image. Since only local images of detection regions are processed, the real-time operation of more than 30 frames per second is realized without using dedicated parallel processors, while ensuring detection performance robust to the variation of weather conditions, shadows, and traffic load.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.37 no.12
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• pp.24-28
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• 2000

This paper reports a new calculation method of three dimensional deposeition rate by level set method. To model an advancement of the surface efficiently, we have developed a new iteration method to re-initialize the level set function. For calculating etching and deposition rate by direct flow, we have developed a visibility test module and a refraction and re-sputtering model. Sputter deposition rate with shadow effect and surface refraction is calculated. We report that difference of profiles in cases that sticking coefficient are 1.0 and 0.3. We report that the difference of the deposition rate on bottom of the hole is caused by a difference of visible angle by the shadowing effect.

• Proceedings of the KIEE Conference
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• 1999.07g
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• pp.2938-2940
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• 1999

도로 색과 대비를 이루는 계수선을 도로위에 그려놓고 영상을 이용하여 통과 차량을 계수 하는 영상기반 교통량 측정 기술을 제안하였다. 기존의 컴퓨터 영상을 이용한 차량 계수 장치들은 대부분 도로와 차량의 gray level차이를 이용하는 방식이기 때문에 도로와 차량간의 구분이 쉽지 않고 그림자와 차량의 식별도 어려우며 조명에 의해 착오를 일으키기 쉬운 문제를 안고 있었다. 제안한 계수방법은 도로 위에 도로 색과 뚜렷한 대비를 이루는 띠를 도로를 가로질러 그려 놓은 다음 이를 통과하는 차량에 의해 띠의 형상이 절단되는지의 여부를 판단하여 차량을 계수 하는 방법이다. 이를 위해서 계수선을 포함하는 영상의 창을 설치하고 수시로 에지를 추출한 후, 에지의 절단 여부를 검사한다. 이때 계수선의 색과 동일한 차량이 통과할 경우에는 계수선의 에지는 절단되어 도로방향으로 연장되게 되며 계수선의 색과 다른 차량인 경우에는 계수선의 에지가 계수선의 내부로 연장되게 된다. 계수선 상에 그림자가 있는 경우에도 도로와 계수선 간의 색상변화가 뚜렷하므로 계수선의 에지 검출에는 영향을 받지 않게 된다. 제안한 알고리즘을 실험실에 설치된 모형도로와 모형 차량들을 이용하여 실험하고 결과를 제시하였다.

• Journal of the Institute of Convergence Signal Processing
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• v.10 no.2
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• pp.112-119
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• 2009

This paper describes a robust visual surveillance algorithm under outdoor environment. One of the difficult problems for outdoor is to obtain effective updating process of background images. Because background images generally contain the shadows of buildings, trees, moving clouds and other objects, they are changed by lapse of time and variation of illumination. They provide the lowering of performance for surveillance system under outdoor. In this paper, a robust algorithm for visual surveillance system under outdoor is proposed, which apply the mixture Gaussian filter and color invariant property on pixel level to update background images. In results, it was showed that the moving objects can be detected on various shadows under outdoor.