• 제목/요약/키워드: Directed projection

검색결과 8건 처리시간 0.029초

IHP 알고리즘을 이용한 SIMO 시스템용 적응 직접 결정 등화기 연구 (An Adaptive Decision-Directed Equalizer using Iterative Hyperplane Projection for SIMO systems)

  • 이원철
    • 한국통신학회논문지
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    • 제30권1C호
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    • pp.82-91
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    • 2005
  • 본 논문은 iterative hyperplane projection 을 이용한 효율적인 APA(affine projection algorithm)을 소개한다. 다양한 적응 알고리즘들 중 APA는 랭크 부족 문제를 해결하며 고속 수렴의 특성 때문에 다양한 응용분야에 적용되고 있다. SIMO(Single-Input-Multiple-Output) 시스템을 위한 STDE(Space-Time Decision- directed Equalizer) 적용 시 흔히 단일 채널 환경에서 발생하는 "shifting invariance property"를 이용할 수 없으므로 인해 FTF(Fast Transversal Filter)와 같이 저 복잡도를 갖는 고속 적응 알고리즘을 사용할 수 없다. 따라서 APA 기반의 STDE 기능을 수행하는 과정에서 SMI(Sample Matrix Inversion) 처리가 불가피하며, 계산상의 복잡도가 증가하게 된다. 이러한 문제점을 해결하고자 본 논문에서는 APA 기법 고유의 우수한 추적 특성 및 고속 수렴 성질을 유지하면서, 낮은 복잡도를 갖는 IHP(Iterative Hyperplane Projection) 알고리즘 기반의 효율적인 수정 APA 기법을 소개한다. 제안된 IHP 기반 APA 기법의 성능을 확인하기 위하여, 무선 SIMO 채널 환경 하에서 제안된 IHP-APA 알고리즘을 적용한 STED에 대한 비트 에러 오률 (BER) 특성과 계산량 분석을 통해서 우수성을 입증하였다.

Orthogonal projection of points in CAD/CAM applications: an overview

  • Ko, Kwanghee;Sakkalis, Takis
    • 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.

3D 프린팅 구조물을 이용한 자기주도 학습방법이 방사선학과 학생들에 미치는 교육 효과 (Educational Effects of Self-directed Learning Method Using 3D Printing Products on Radiological Science Students)

  • 성열훈
    • 한국방사선학회논문지
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    • 제14권1호
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    • pp.45-51
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    • 2020
  • 본 연구에서는 방사선영상학 수업에서 3D 프린팅 해부학 구조물을 이용한 자기주도 학습이 교육 효과에 미치는 영향을 분석하고자 하였다. 대상은 4년제 대학교의 방사선학과 2학년의 32명(남자: 20명, 여자: 12명)으로 방사선영상학 교과목을 수강한 재학생들로서 소극적인 학생 그룹과 적극적인 학생 그룹으로 구분하였다. 학습방법은 3D 프린팅 해부학적 구조물을 이용한 자기주도 학습으로 진행했으며 학습 전·후로 정량적 학습개선효과를 평가하였다. 학생들의 정성적인 평가를 위해 수업의 흥미도, 만족도 그리고 학습효과(해부학 명칭 암기 용이성, X선 영상 해독력, 해부학 구조물 이해도, X선 촬영법 이해도)에 대해서 5점 리커트 5점 척도로 분석하였다. 그 결과 학습개선효과는 평균 65.4%가 향상되었으며 모든 학생들이 모든 변수에서 높은 점수를 얻었다 특히, 흥미도와 X선 영상 해독력을 제외한 모든 변수에서 소극적 학생그룹이 적극적인 학생그룹보다 높은 상관계수를 보였다. 이러한 결과는 3D 프린팅 해부학 구조물을 이용한 자기주도 학습이 방사선학과 학생들에게 긍정적인 교육효과를 기대할 수 있다.

상황인식에 대한 측정 및 차세대 원자로 운전원 성능 평가에서의 활용방법에 관한 이론 연구 (A Review on Measurement and Applications of Situation Awareness for an Evaluation of Korea Next Generation Reactor Operator Performance)

  • 이동하;이현철
    • 산업공학
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    • 제13권4호
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    • pp.751-758
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    • 2000
  • Situation awareness is defined as a person's perception of the elements of the environment within a volume of time and space, the comprehension of their meaning and the projection of their status in the near future. Situation awareness is important in attempting to evaluate human behavior in operating complex systems such as aircraft, air traffic control, and nuclear power plant systems. From the literatures this study reviews the relationship between situation awareness and numerous individual, system and environmental factors, and also reviews the methodologies for the empirical measurement of situation awareness applicable to Korea Next Generation Reactor (KNGR) design project. Attention, working memory, workload, stress, system complexity, and automation are presented as critical factors limiting operator's situation awareness. Mental models and goal-directed behavior are hypothesized as important mechanisms overcoming these limits. This study summarized hypothesized guidelines for interface design to improve situation awareness of reactor operators. Some of the guidelines should be tested in the KNGR evaluation experiments in the future.

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HOUGH 변환을 이용한 차량 검지 기술 개발을 위한 모형 (New Method for Vehicle Detection Using Hough Transform)

  • Kim, Dae-Hyon
    • 대한교통학회지
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    • 제17권1호
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    • pp.105-112
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    • 1999
  • 차량대수, 속도, 대기행렬길이, 정체 및 유고 검지 등의 실시간 교통 정보를 얻기 위하여 현재 영상처리기술(Image Processing technique)이 기존의 루프검지기(Loop Detector)가 갖는 여러 단점들을 보완하는 효과적인 대체검지기로 널리 인식되고있다. 그러나 현재 사용되는 대부분의 영상검지기는 아주 작은 영역에서의 흑백 강도값(gray level)를 사용하며, 따라서 검지기의 정확도는 취급하는 영상의 화질에 크게 영향을 밭을 뿐만 아니라 3차원 실제 공간이 2차원 영상평면으로 표출되므로 생기는 투시사영(perspective projection)문제에 효과적으로 대처할 수 없다. 이런 문제 때문에 현재 영상검지기는 가능한 한 높게 그리고 도로면에 수직으로 카메라를 설치하여 가능한 한 평면화 된 2차원의 영상을 얻어 처리한다. 그러나 이는 한대의 검지기가 포함할 수 있는 영역이 매우 작을 뿐만 아니라, 가능한 한 카메라를 높게 설치해야 하므로 현실적으로 많은 어려움이 따른다. 본 연구에서는 카메라의 설치 위치 또는 각도에 따라 인식율의 정확도에 큰 차이를 보이는 기존의 알고리즘에서 탈피하여, 낮은 위치에 설치할 때 나타나는 투시사영 문제 및 물체 영상의 일부가 가려져 다음 물체의 인식이 곤란한 문제 등을 해결하기 위한 새로운 방법을 제시하였다. 본 연구에서 제시된 방법은 차량의 검지뿐만 아니라 차량의 위치, 3차원 공간에서의 차량의 관계 등에 관한 정보를 얻을 수 있으며, 사용된 알고리즘은 3차원 공간에서의 물체 인식에 우수한 확장된 Hough Transform에 기초하고 있다.

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MDCT에서 Curved MPR을 이용한 효과적인 영상진단 (The Effective Image Diagnosis Using Curved MPR from MDCT)

  • 송종남;장영일
    • 대한디지털의료영상학회논문지
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    • 제12권2호
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    • pp.139-143
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    • 2010
  • Two-dimensional(2D) images like Multi Planar Reconstruction(MPR) Image or Maximum Intensity Projection(MIP) were used for the purpose of diagnosis, but MPR image's quality were limited due to its superior limit of Z-axis ability to produce permitted radiation exposure virtuous in the permitted time limit from the existing Spiral CT. However, in company with the development of the Multi Detector Computed Tomography(MDCT), we were able to get the Data with the equal amount of Voxel, also get varied reconstructions as in the aspect of our needs. This present study propose a reconstruction technique which is to extract a field using Region of interest(ROI) segmentation method for improvement of the quality of the medical image and after that reconstruct the concerned part using the four-directed symmetry method of the oval, than using the reconstructed data, reorganize the image by using the Curved MPR method. If current proposed method is used, it is highly effective because of its ability to accurately display the disease concerned part, which will reduce the decoding time and also effectively provide information based on the accuracy of the decode.

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서울지하철 범죄 실태에 대한 범죄심리학적 연구 (Study on the Realities in Seoul Subway Crimes: Criminal Psychology)

  • 임상곤
    • 시큐리티연구
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    • 제7호
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    • pp.233-285
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    • 2004
  • ‘Defined legally as a violation of law' (Sutherland, E. H. Principles of Criminology, Lippincott, Chicago, 1939) Crime within the group is essentially and primarily antisocial in that the criminal who is welfare of his group acts instead against it and breaks the principles of social solidarity not merely by not doing what these principles prescribe, but by doing something exactly opposites. Any program set up to attack crime and delinquent behavior at their sources. A program of his nature needs the constant and comprehensive collaboration of psychiatrists, social works, educations, lawmakers, and public officials, since crime is a social problem and it should be treated as such. Some crime preventives which should be mentioned are as follows, (1) The insurance that every child will be decently born and that his home life be socially and economically adequate; without socially mature parents the chid is handicapped at the start; thus parental education, integrated with the public school system, should be developed now. (2) A more meaningful educational program which would emphasize ideals of citizenship, moral integrity, and respect for the law and the police. (3) A periodic check made for potential delinquents throughout the public schools and treatment provided if possible; and if not, proper segregation in institutions. (4) Careful attention paid to press, movies, and radio so that crime may no longer appear to be glamorous. This can be done by women's clubs, civic bodies, and other educational groups exerting pressure on the movie syndicates and broadcasting companies to free their productions of the tawdry and lurid characteristics of crime and criminals. Aggression associated with the phallic stage of development, The child ordinarily comprehends sexual intercourse as an aggressive and sadistic act on the part of the male, and specifically on the part of the penis. Evidence that the penis is phantasied as a weapon of violence and destruction come from unconscious productions of normal adults. Limerick, for instance, often refer to the penis as square, or too large, etc., so that intercourse is dangerous and painful for the partner, This may wall be a projection of the male's own fear of coitus. A certain portion of the death-instinct always remains within the person; it is called 'primal sadism' and according to Freud is identical with masochism. 'After the chief part of it(the death instinct) has been directed outwards towards objects, there remains as a residuum within the organism the true erotogenic masochism, which on the one hand becomes a component of the libido and on the other still has the subject itself for a object.' Criminalism, compulsive-neurotic frequent repetition of criminal acts in a compulsive manner. Like most symptoms of the compulsive-neurotic, such antisocial act are closely rated to feelings of hostility and aggression, often against the father. Because these acts are symptomatic, they afford only temporary relief and are therefore repeated. One patient with compulsive-neurotic criminalism was apprehended after breaking into hardware store and stealing money. He later confessed to many similar incidents over the preceding two years. At the same time it was apparent that he stole only for the sake of stealing. He did not need the money he thus obtained and had no special plans for using it.

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Holographic phase gratings in back- and frontlights for LCD's

  • Bastiaansen, C.W.M.;Heesch, C. van;Broer, D.J.
    • 한국정보디스플레이학회:학술대회논문집
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    • 한국정보디스플레이학회 2006년도 6th International Meeting on Information Display
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    • pp.421-421
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    • 2006
  • The light and energy-efficiency of classical liquid crystal displays is notoriously poor due to the use of absorption-based linear polarisers and colour filters. For instance, the light efficiency of PVAL polarisers is typically between 40 and 45 % and the colour filters have a typical efficiency below 35 % which results in a total light and energy-efficiency of the display below 10 %. In the past, a variety of polarizers were developed with an enhanced efficiency in generating linearly polarized light. Typically, these polarizers are based on the polarisationselective reflection, scattering or refraction of light i.e. one polarisation direction of light is directly transmitted to the LCD/viewer and the other polarization direction of light is depolarised and recycled which results in a typical efficiency for generating linearly polarized light of 70-85 %. Also, special colour filters have been proposed based on chiral-nematic reactive mesogens which increase the efficiency of generating colour. Despite the enormous progress in this field, a need persists for improved methods for generating polarized light and colour based on low cost optical components with a high efficiency. Here, the use of holographic phase gratings is reported for the generation of polarized light and colour. The phase grating are recorded in a photopolymer which is coated onto a backor frontlight for LCDs. Typically the recording is performed in the transmisson mode or in the waveguiding mode and slanted phase gratings are generated with their refractive index modulation at an angle between 20o and 45o with the normal of the substrate. It is shown that phase gratings with a high refractive index modulation and a high efficiency can be generated by a proper selection of the photopolymer and illumination conditions. These phase gratings coupleout linearly polarized light with a high contrast (> 100) and the light is directed directly to the LCD/viewer without the need for redirection foils. Dependent on the type of phase grating, the different colours are coupled-out at a slightly different angle which potentially increases the efficiency of classical colour filters. Moreover, the phase gratings are completely transparent in direct view which opens the possibility to use them in frontlights for LCDs. Holographic polarization gratings posses a periodic pattern in the polarization state of light (and not in the intensity of light). A periodic pattern in the polarization direction of linearly polarized light is obtained upon interference of two circularly polarized laser beams. In the second part of the lecture, it is shown that these periodic polarization patterns can be recorded in a linear photo-polymerizable polymer (LPP) and that such an alignment layer induces a period rotation in the director of (reactive and non-reactive) liquid crystals. By a proper design, optical components can be produced with only first order diffraction and with a very high efficiency (>0.98). It is shown that these diffraction gratings are potentially useful in projection displays with a high brightness and energy efficiency

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