• 치과방사선
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• 제4권1호
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• pp.31-37
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• 1974

The author has studied roentgenographic images of temporomandibular articulation using various conventional roentgenographies. The roentgenographic images have obtained by application of the contrast media on the glenoid fossa and condylar head in a human dry skull. Comparing the various roentgenograms by Modified Transcranial projection, A-P T.M. articulation projection, Reverse Towne projection, Mayer projection and Bregma-Menton projection. The author has drawn following results. 1. The sharp radiogaphic details were obtained by all technics used except the Bregma-Menton projection, which seemed to be impractical to the study of T.M.J. because of to be shortened the image of condylar head. 2. The best image of the condyle-fossa relationship was appeared by Modified Transcranial projection and better image was acquired by Orbito-Ramus projection, but there were all inferior in Reverse Towne projection, Mayer projection and Bregma-Menton projection. 3. In all of the above techniques, the radiographic images of condylar head were clear and were appeared to be the convex type in Modified Transcranial projection, the angled type in Orbito-Ramus and Reverse Towne projection, the flat type in Mayer projection and the distorted angled type in Bregma-Menton projection. 4. The radiographic image of condylar head was shortened in Bregma-Menton projection only and was magnified somewhat in other projection.

• Journal of Computational Design and Engineering
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• 제1권2호
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• pp.116-127
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• 2014

This paper aims to review methods for computing orthogonal projection of points onto curves and surfaces, which are given in implicit or parametric form or as point clouds. Special emphasis is place on orthogonal projection onto conics along with reviews on orthogonal projection of points onto curves and surfaces in implicit and parametric form. Except for conics, computation methods are classified into two groups based on the core approaches: iterative and subdivision based. An extension of orthogonal projection of points to orthogonal projection of curves onto surfaces is briefly explored. Next, the discussion continues toward orthogonal projection of points onto point clouds, which spawns a different branch of algorithms in the context of orthogonal projection. The paper concludes with comments on guidance for an appropriate choice of methods for various applications.

• 대한의용생체공학회:의공학회지
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• 제15권3호
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• pp.275-280
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• 1994

In the case of the image reconstruction from unknown projection data such as imaging the object with opaque obstructions, conventional reconstruction algorithms may reconstruct a degraded image. In this paper, a new method for the estimation of the unknown projection data based on known projection data and the bandwidth of projection data is proposed. The proposed method successfully estimates the unknown projection data through iterative transformation between projection space and frequency space using the known projection data and the bandwidth of the projection data. Computer simulation shows that the proposed method significantly improves image quality and convergence behavior over conventional algorithms. In addition, the proposed method is successfully applied to ultrasound attenuation CT using a sponge phantom.

• 한국통신학회논문지
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• 제24권9B호
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• pp.1785-1794
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• 1999

Affine projection 알고리즘은 RLS보다 적은 계산량으로 LMS보다 우수한 수렴성능을 나타낸다. 그러나 affine projection 알고리즘은 역행렬 연산을 필요로 하기 때문에 여전히 LMS에 비해 과중한 계산을 필요로 한다. 본 논문에서는 affine projection 알고리즘을 분석하여 이 알고리즘이 Gram-Scheme 구조로 해석될 수 있음을 보이고 이를 이용하여 NLMS와 비슷한 계산량으로 affine projection 알고리즘을 근사적으로 구현할 수 있는 새로운 알고리즘을 제안하였다. 제안한 방법은 NLMS와 비슷한 계산량을 가지면서 기존의 affine projection 알고리즘과 비슷한 수렴성능을 나타내었다.

• 한국인구학
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• 제33권2호
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• pp.85-111
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• 2010

한국사회가 최근 초저출산율이 지속되고, 사망율이 괄목할 만큼 개선되면서 장래인구 추계는 새로운 도전을 받고 있다. 이 연구는 장래 인구를 보다 정확한 예측하고, 양질의 정보를 제공하기 위한 방안을 한국의 경우를 중심으로 여타 저출산 국가들과 비교연구를 통해 논의하였다. 구체적으로 이 연구는 1) 통계청이 실시한 2009년도 인구추계를 2006년도 공식 인구추계와 비교분석 하였고, 2) 한국의 인구추계방식을 다른 나라의 경우와 비교 분석하였다. 비교에는 어떤 기관이 인구추계를 담당하는지, 얼마나 먼 장래까지 추계 하는지, 얼마나 자주 행해지는지, 그리고 추계에 사용되는 출산, 사망, 이주에 관련된 가정과 시나리오의 수를 고려하였다. 3) 향후 50년간장래인구를 확률적 인구추계 방식을 도입하여 예측해 보았다. 4) 마지막으로 2011년 장래인구추계에 사용될 시나리오를 살펴보았다. 이러한 논의를 바탕으로 이 연구는, 장래인구추계의 정확성을 높이기 위해서 인구추계를 좀더 자주 실시할 것과, 단기와 장기추계의 구분, 시나리오 수를 기존 네 가지에서 더 늘릴 것을 제안하였다. 또한 기준인구 산정에 있어 국내 체류중인 외국인 인구를 고려할 것과 확률적 인구추계 방식도 도입할 것을 제안하였다.

• Advances in robotics research
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• 제2권1호
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• pp.45-57
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• 2018

Even though the popularity of projection mapping continues to increase and it is being implemented in more and more settings, most current projection mapping systems are limited to special purposes, such as outdoor events, live theater and musical performances. This lack of versatility arises from the large number of projectors needed and their proper calibration. Furthermore, we cannot change the positions and poses of projectors, or their projection targets, after the projectors have been calibrated. To overcome these problems, we propose a projection mapping method using a projector robot that can perform projection mapping in more general or ubiquitous situations, such as shopping malls. We can estimate a projector's position and pose with the robot's self-localization sensors, but the accuracy of this approach remains inadequate for projection mapping. Consequently, the proposed method solves this problem by combining self-localization by robot sensors with position and pose estimation of projection targets based on a 3D model. We first obtain the projection target's 3D model and then use it to accurately estimate the target's position and pose and thus achieve accurate projection mapping with a projector robot. In addition, our proposed method performs accurate projection mapping even after a projection target has been moved, which often occur in shopping malls. In this paper, we employ Ubiquitous Display (UD), which we are researching as a projector robot, to experimentally evaluate the effectiveness of the proposed method.

• 한국정보과학회논문지:시스템및이론
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• 제31권3_4호
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• pp.195-203
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• 2004

볼륨프로는 일반 PC상에서도 실시간 볼륨렌더링이 가능하도록 고안된 하드웨어이다. 그러나 볼륨프로는 직교투영(orthographic projection) 기능만 제공하기 때문에 가상 내시경과 같이 투시투영 (perspective projection)이 필요한 분야에는 이용할 수 없다. 이런 문제를 해결하기 위해 볼륨 데이터를 여러 개의 슬랩(slab)으로 분할하여 투시투영을 근사 하는 방법이 소개되었으나 이 방법은 시각 절두체에 포함되지 않은 부분까지 렌더링 하기 때문에 처리시간이 길어지는 문제가 있다. 본 논문에서는 볼륨프로의 크로핑(cropping) 기능을 이용하여 볼륨 데이타를 여러 개의 서브볼륨으로 분할함으로써 효율적인 투시투영이 가능하도록 하는 방법을 제안한다. 이 방법은 시각 절두체(view frustum)에 포함되는 부분만 렌더링하므로 슬랩을 이용하는 기존 방법과 동일한 화질을 가지면서 처리시간을 단축시킨다.

• Journal of applied mathematics & informatics
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• 제8권2호
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• pp.651-658
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• 2001

The projection matrix plays an important role in the linear model theory. In this paper we derive an algebraic relationship between the projection matrices of submatrices of the design matrix. Using this relationship we can easily obtain the projection matrices of any submatrices of the design matrix. Also we show that every projection matrix can be obtained as a linear combination of Kronecker products of identity matrices and matrices with all elements equal to 1.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2002년도 가을 학술발표회 논문집
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• pp.615-622
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• 2002

In this paper, the modification of double projection method for the adaptive analysis of Element-free Galerkin(EFG) method were proposed. As results of the double projection method, the smoothed error profile that is adequate for adaptive analysis was obtained by re-projection of error that means the differences of EFG stress and projected stress. However, it was found that the efficiency of double projection method is degraded as increase of the numerical integration order. Since, the iterative refinement to single step error estimation made the same effect as increasing of integration order, the application of the iterative refinement base on double projection method could be produced the inadequately refined analysis model. To overcome this defect, a modified scheme of double projection were proposed. In the numerical example, the results did not show degradation of double projection effect in iterative refinement and the efficiency of proposed scheme were proved.

• 한국통신학회논문지
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• 제21권9호
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• pp.2341-2348
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• 1996

This paper proposes an image compression algorithm that adopts projection scheme on mean-residual metod. Sub-blocks of an image are encoded using mean-residual method where mean value is predicted according to that of neighboring blocks. Projection scheme with 8 directions is applied to the compression of residual signals of blocks. Projection vectors are finite-state vector quantized according to the projection angle of nighboring blocks in order to exploit the correlation among them. Side information to represent the repetition of projection is run-length coded while the information for projection direction is compressed using entropy encoding. The proposed scheme apears to be better in PSNR performance when compared with conventional projection scheme as well as in subjective quality preserving the edges of images better than most tranform methods which usually require heavy computation load.