• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.11
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• pp.66-72
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• 2014

Histogram of oriented gradient (HOG) feature is widely used in vision-based pedestrian detection. The interpolation is the most important technique in HOG feature calculation to provide high detection rate. In interpolation technique of HOG feature calculation, two nearest orientation bins to gradient orientation for each pixel and the corresponding weights are required. In this paper, therefore, an efficient gradient orientation bin and weight calculation circuit for HOG feature is proposed. In the proposed circuit, pre-calculated values are defined in tables to avoid the operations of tangent function and division, and the size of tables is minimized by utilizing the characteristics of tangent function and weights for each gradient orientation. Pipeline architecture is adopted to the proposed circuit to accelerate the processing speed, and orientation bins and the corresponding weights for each pixel are calculated in two clock cycles by applying efficient coarse and fine search schemes. Since the proposed circuit calculates gradient orientation for each pixel with the interval of $1^{\circ}$ and determines both orientation bins and weights required in interpolation technique, it can be utilized in HOG feature calculation to support interpolation technique to provide high detection rate.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.5
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• pp.5-10
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• 2003

• Proceedings of the Korea Multimedia Society Conference
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• 2003.05b
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• pp.410-414
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• 2003

본 논문은 비디오 시퀀스에 카메라 패닝 보상과 2차원 시공간 엔트로피 임계법을 적용하여 추출한 객체포함영역을 대상으로 영상 분할을 수행하는 이동 객체 분할 기법에 관한 것이다. 우선, 웨이블렛 변환에 의해 구성한 피라미드 계층 구조상에서 카메라 패닝 벡터를 추정하여 전역 움직임을 보상한다. 이후, 전역 움직임이 보상된 기준영상을 대상으로 각 프레임간에서 2차원 시공간 엔트로피 임계법을 적용하여 이동 객체가 포함될 가능성이 있는 영역을 블록 단위로 추출한다. 다음으로, 2차원 시공간 엔트로피 입계법에 의해 분류된 영역을 토대로 각 블록을 움직임블록, 준 움직임 블록, 비 움직임 블록 중 어느 하나로 분류한 검색 테이블을 작성한다. 이어서, 검색 테이블을 참조하여 초기 탐색 계층 및 탐색 영역을 적응적으로 선정함으로써 피라미드 계층 구조상에서 효율적인 고속 움직임 추정을 수행하여 이동 객체에 해당하는 객체포함영역만을 추출한다. 최종적으로, 이렇게 추출된 객체포함영역에서 임계 기울기 영상을 정의한 후, 이를 기준 삼아 객체포함영역에 화소 단위의 형태학 기반 영상 분할 알고리즘을 적용함으로써 비디오 시퀀스에 포함된 이동 객체를 분할한다. 컴퓨터 시뮬레이션 결과를 통해 고찰할 때, 제안된 방법은 이동 객체에 대한 상대적으로 우수한 분할 특성을 제공할 수 있고, 특히 저대조 경계면의 분할 특성을 제고시키고 있음을 확인할 수 있다.

• Annual Conference on Human and Language Technology
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• 1999.10e
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• pp.184-190
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• 1999

본 논문에서는 Text-to-Speech 시스템에서 사용할 억양 모델을 위해 음성 DB에서 모델 파라미터와 피치 검색테이블(lookup-table)을 추출하여 미리 구성하고, 합성시에는 이를 추정하여 최종 F0 값을 생성하는 자료기반 접근방식(data-driven approach)을 사용한다. 어절 경계강도(break-index)는 경계강도의 특성에 따라 고정적 경계강도와 가변적 경계강도로 세분화하여 사용하였고, 예측된 경계강도를 기준으로 억양구(Intonation Phrase)와 액센트구(Accentual Phrase)를 설정하였다. 특히, 액센트구 모델은 인지적, 음향적으로 중요한 정점(peak)을 정확하게 모델링하는 것에 주안점을 두어 정점(peak)의 시간축, 주파수축 값과 이를 기준으로 한 앞뒤 기울기를 추정하여 4개의 파라미터로 설정하였고, 이 파라미터들은 CART(Classification and Regression Tree)를 이용하여 예측규칙을 만들었다. 경계음조가 나타나는 조사, 어미는 정규화된(normalized) 피치값과 key-index로 구성되는 검색테이블을 만들어 보다 정교하게 피치값을 예측하였다. 본 논문에서 제안한 억양 모델을 본 연구실에서 제작한 음성합성기를 통해 합성하여 청취실험을 거친 결과, 기존의 상용 Text-to-Speech 시스템에 비해 자연스러운 합성음을 얻을 수 있었다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.20-23
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• 2002

In silicon wafer manufacturing process, the grinding process has been adopted to improve the quality of wafer such as flatness, roughness and so on. This paper describes the effect of grinding process on the surface quality of wafer. The experiments are carried out by high precision in fred grinder with air bearing spindle. The relationship between the inclination of chuck table and the flatness of wafer is investigated, and the effect of grinding conditions including wheel speed, table speed, and feed rate on damage depth and roughness of wafer is also investigated. The experimental results show that there is close relationship between the inclination of the chuck table and the flatness of wafer, and the grinding conditions within this paper little affect the flatness of wafer and relatively high affect the damage depth of wafer.

• Journal of radiological science and technology
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• v.44 no.4
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• pp.367-373
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• 2021

A quality assurance of computed tomography(CT) have done seven items that were water attenuation coefficient, noise, homogeneity, spatial resolution, contrast resolution, slice thickness, artifact using by standard phantom. But there is no quality assurance items and methods for CT simulator at domestic institutions yet. Therefore the study aimed to access the CT dose index(CTDI), table tilting, image distortion, laser accuracy, table movement accuracy and CT seven items for CT simulator quality assurance. The CTDI at the center of the head phantom was 0.81 for 80 kVp, 1.55 for 100 kVp, 2.50 for 120 mm, 0.22 for 80 kVp at the center of the body phantom, 0.469 for 100 kVp, and 0.81 for 120 kVp. The table tilting was within the tolerance range of ±1.0° or less. Image distortion had 1 mm distortion in the left and right images based on the center, and the laser accuracy was measured within ±2 mm tolerance. The purpose of this study is to improve the quality assurance items suitable for the current situation in Korea in order to protect the normal tissues during the radiation treatment process and manage the CT simulator that is implemented to find the location of the tumor more clearly. In order to improve the accuracy of the CT simulator when looking at the results, the error range of each item should be small. It is hoped that the quality assurance items of the CT simulator will be improved by suggesting the quality assurance direction of the CT simulator in this study, and the results of radiation therapy will also improve.

• Journal of Korea Multimedia Society
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• v.5 no.6
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• pp.609-615
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• 2002

In this paper, we propose a contrast for the improvement of multi-gray scale image on display system. The proposed method distinguishes a maximum value and a minimum value in input fields or frames. By this judgement, the improvement degree of image quality is decided. This method does not require field and frame memory. Moreover, its lower hardware complexity than conventional methods make it easy to apply this method for flat panel display(FPD) which requires real-time processing. And the contrast of input gray level can be controled flexibly by varying the weight the weight value which controls the contrast range. The proposed method gives an image by controlling weighting slope selectively at intervals according to the brightness-control algorithm and the type of image in the look-up table. The function of the proposed method has been verified through Synopsys VHDL and computer simulation. And its results show that the proposed method can improve the quality of image.

• The Transactions of the Korea Information Processing Society
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• v.4 no.10
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• pp.2553-2561
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• 1997

In this paper, a hardware architecture to calculate straight-line Hough transform algorithm for image recognition is suggested. This processor consists of the filtering module for gradient calculation and the HT calculation module, and the angle information are stored in memory table. For the suggested architecture, firstly, algorithm simulation is executed using C language to confirm the operation and to decide the precision of calculation, and secondly, architecture simulation is executed using VHDL language for the total blocks. According to C & VHDL simulation results, it is confirmed that the calculated data value is similarly obtained and the calculation defference is decreased as image clarity and bits increase.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.4 no.3
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• pp.126-133
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• 2003

This paper is related to a morphological segmentation method for extracting the moving object in video sequence using global motion compensation and two-dimensional spatio-temporal entropic thresholding. First, global motion compensation is performed with camera panning vector estimated in the hierarchical pyramid structure constructed by wavelet transform. Secondly, the regions with high possibility to include the moving object between two consecutive frames are extracted block by block from the global motion compensated image using two-dimensional spatio-temporal entropic thresholding. Afterwards, the LUT classifying each block into one among changed block, uncertain block, stationary block according to the results classified by two-dimensional spatio-temporal entropic thresholding is made out. Next, by adaptively selecting the initial search layer and the search range referring to the LUT, the proposed HBMA can effectively carry out fast motion estimation and extract object-included region in the hierarchical pyramid structure. Finally, after we define the thresholded gradient image in the object-included region, and apply the morphological segmentation method to the object-included region pixel by pixel and extract the moving object included in video sequence. As shown in the results of computer simulation, the proposed method provides relatively good segmentation results for moving object and specially comes up with reasonable segmentation results in the edge areas with lower contrast.

• Progress in Medical Physics
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• v.25 no.4
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• pp.193-198
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• 2014

The purpose of this study is to see the feasibility of the newly developed 2D dosimetry system using phosphor screen for helical tomotherapy. The cylindrical water phantom was fabricated with phosphor screen to emit the visible light during irradiation. There are three types of virtual target, one is one spot target, another is C-shaped target, and the other is multiple targets. Each target was planned to be treated at 10 Gy by treatment planning system (TPS) of tomotherapy. The cylindrical phantom was placed on the tomotherapy table and irradiated as calculations of the TPS. Every frame which acquired by CCD camera was integrated and the doses were calculated in pixel by pixel. The dose distributions from the fluorescent images were compared with the calculated dose distribution from the TPS. The discrepancies were evaluated as gamma index for each treatment. The curve for dose rate versus pixel value was not saturated until 900 MU/min. The 2D dosimetry using the phosphor screen and the CCD camera is respected to be useful to verify the dose distribution of the tomotherapy if the linearity correction of the phosphor screen improved.