• Journal of the Institute of Electronics Engineers of Korea SP
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• v.44 no.4 s.316
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• pp.117-122
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• 2007

For multiple antenna systems, we consider the hybrid iterative detection of the maximum a posteriori probability(MAP) detection and the linear detection such as the minimum-mean-square-error(MMSE) filtering with soft cancelation. We devise methods to obtain both the lower complexity of the linear detection and the superior performance of the MAP detection. Using the a prior probability of the coded bit which is extrinsic of the outer decoder, we compute the threshold of grouping and determine the detection scheme symbol by symbol. Through the simulation results, it is shown that the proposed receiver obtains the superior performance to the MMSE detector and the lower complexity than the MAP detector.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.7C
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• pp.587-593
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• 2010

In this paper we design an irregular low-density parity-check (LDPC) code for multiple-input multiple-output (MIMO) system, using a simple extrinsic information transfer (EXIT) chart method. The MIMO systems considered are optimal maximum a posteriori probability (MAP) detector. The MIMO detector and the LDPC decoder exchange soft information and form a turbo iterative receiver. The EXIT charts are used to obtain the edge degree distribution of the irregular LDPC code which is optimized for the MIMO detector. It is shown that the performance of the designed LDPC code is better than that of conventional LDPC code which was optimized for either the Additive White Gaussian Noise (AWGN) channel or the MIMO channel.

• Journal of KIISE:Software and Applications
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• v.34 no.11
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• pp.961-970
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• 2007

Since the usual conventional edge detectors employ the local differential derivatives, the detected edges are not uniform in their widths or some edges are missed out of the detection on magnified images. We employ a mapping from the exactly monotonic intensity distributions of ramp edges to the simple step functions of intensity, which is referred to as perfect sharpening map of ramp edges. This map is based on the non-local feature of intensity distribution and used to introduce a modified differentiation, in terms of which we can construct an efficient edge detector adaptive to the variation of edge width. By adopting the operator MADD in this paper, we developed an edge detector that works stably against the magnification of image or the variation of edge width. It is shown by comparing to the conventional algorithms that the proposed one is very excellent.

• Progress in Medical Physics
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• v.25 no.2
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• pp.65-71
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• 2014

A Varian Portal Dosimetry system was compared to an isocentrically mounted MapCHECK 2 diode array for volumetric modulated arc therapy (VMAT) QA. A Varian TrueBeam STx with an aS-1000 digital imaging panel was used to acquire VMAT QA images for 13 plans using four photon energies (6, 8, 10 and 15 MV). The EPID-based QA images were compared to the Portal Dose Image Prediction calculated in the Varian Eclipse treatment planning system (TPS). An isocentrically mounted Sun Nuclear MapCHECK 2 diode array with 5 cm water-equivalent buildup was also used for the VMAT QAs and the measurements were compared to a composite dose plane from the Eclipse TPS. A ${\gamma}$ test was implemented in the Sun Nuclear Patient software with 10% threshold and absolute comparison at 1%/1 mm (dose difference/distance-to-agreement), 2%/2 mm, and 3%/3 mm criteria for both QA methods. The two-tailed paired Student's t-test was employed to analyze the statistical significance at 95% confidence level. The average ${\gamma}$ passing rates were greater than 95% at 3%/3 mm using both methods for all four energies. The differences in the average passing rates between the two methods were within 1.7% and 1.6% of each other when analyzed at 2%/2 mm and 3%/3 mm, respectively. The EPID passing rates were somewhat better than the MapCHECK 2 when analyzed at 1%/1 mm; the difference was lower for 8 MV and 10 MV. However, the differences were not statistically significant for all criteria and energies (p-values >0.05). The EPID-based QA showed large off-axis over-response and dependence of ${\gamma}$ passing rate on energy, while the MapCHECK 2 was susceptible to the MLC tongue-and-groove effect. The two fluence-based QA techniques can be an alternative tool of VMAT QA to each other, if the limitations of each QA method (mechanical sag, detector response, and detector alignment) are carefully considered.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.209-209
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• 2012

전자의 에너지를 측정하기 위한 분석장치는 원자핵물리뿐만 아니라 화학과 생물학 등 다양한 분야에 걸쳐 매우 유용하게 사용될 수가 있다. 특히 최근에 극고속 과학과 관련해서 매우 짧은 펄스인 아토초 펄스의 발생에 대한 특성평가를 위해 매우 중요한 장치로 사용되고 있다. 그 중 VMI (Velocity Map Imaging) 방법은 TOF (Time of Flight) 방법과 유사하지만, CCD 카메라를 추가로 사용하여 이차원 이미지를 얻음으로써 전자의 운동에너지 및 각도 분포에 대한 정보를 얻을 수 있고 또한 전극에 인가되는 전압은 TOF와 달리 매우 높다. 이번 개발에서는 기존의 전극 렌즈의 geometry와 비교해서 VMI Spectrometer 전극 렌즈의 수를 늘려 multi-electrode concept을 도입함으로써 높은 운동에너지(~1000 eV)를 가진 전자들을 MCP detector상에서 imaging 하는데 있어 높은 공간 분해능(resolution)을 갖도록 설계하고, 또한 높은 사양의 MCP detector 및 CCD 카메라를 이용하여 시간 분해능을 높임으로써 아토초 펄스를 이용한 극고속 실험에 이용 가능하도록 제작하였다.

• Journal of information and communication convergence engineering
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• v.12 no.3
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• pp.193-197
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• 2014

Edges are a robust feature for object detection. In this paper, we present an edge-based background modeling method for the detection of moving objects. The edges in the image frames were mapped using robust Canny edge detector. Two edge maps were created and combined to calculate the ultimate moving-edge map. By selecting all the edge pixels of the current frame above the defined threshold of the ultimate moving edges, a temporary background-edge map was created. If the frequencies of the temporary background edge pixels for several frames were above the threshold, then those edge pixels were treated as background edge pixels. We conducted a performance comparison with previous works. The existing edge-based moving-object detection algorithms pose some difficulty due to the changes in background motion, object shape, illumination variation, and noises. The result of the performance evaluation shows that the proposed algorithm can detect moving objects efficiently in real-world scenarios.

• Electronics and Telecommunications Trends
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• v.22 no.5
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• pp.95-107
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• 2007

X-선 측정 및 영상장치를 포함한 다양한 응용분야에서 방사선에 대한 고해상도의 영상을 얻기 위한 목적으로 반도체 검출기에 대한 개발이 활발히 진행되고 있다. 본 고에서는 방사선 검출을 위해 요구되는 반도체 물질의 주요 특성에 대해서 조사하였다. 또한 반도체를 이용한 플랫 패널(flat panel) 시스템, 픽셀 디텍터(pixel detector)와 스트립 디텍터(strip detector) 등의 혼성형 디텍터(hybrid detector), MAPS와 DEPFET 등의 단일형 픽셀 디텍터(monolithic pixel detector)의 디바이스 동작 원리 및 특성과 국내외 기술 동향에 대하여 살펴보았다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.7
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• pp.1479-1484
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• 2005

This paper represents an intelligent sensor controller of mobile robot for object recognition in an indoor hon environment. A range finder sensor module has been developed by using optic PSD (Position Sensitive Detector) sensor way at a low Vice. While PSD sensor is cost effective and light weighting, it has switching noise and white noise. To remove these noises, we propose a heuristic filter. For line-based map building. also we prorosed advanced Hough transformation and navigation algorithm. Some experiments were illustrated for the validity of the developed system.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.2
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• pp.191-194
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• 2005

This paper represents an intelligent sensor controller of mobile robot for object recognition in an indoor known environment. A range finder sensor module has been developed by using optic PSD (Position Sensitive Detector) sensor array at a low price. While PSD sensor is cost effective and light weighting, it has switching noise and while noise. To remove these noises, we propose a heuristic filter. For line-based map building, also we proposed advanced Hough transformation and navigation algorism. Some experiments were illustrated for the validity of the developed system.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.10
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• pp.1897-1904
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• 2006

Home service robot must recognize and build map for indoor and components of the house such as furniture and chair etc. The previous researcher has developed a indoor map building system by using CCD camera and ultra sonic sensor. %no stems have some problem in such a way that (1) a distun resolution can be changed according to the number of pixel when we use a CCD camera system, (2) a measured distance can be decreased when it transmitted to the rubber because of being absorbed the sound energy. This paper represents an intelligent sensor controller of module has been developed by using optic PSD(Position Sensitive Detector) sensor any at a low price. To deduce the switching noise from beam power module and diffused reflection noise, we proposed a heuristic soft filter. The performance of the developed system was compared with ultra sonic sensor system by detecting the indoor wall environment. Some experiments were illustrated for the validity of the developed system.