• Title/Summary/Keyword: Piecewise linear transformation method

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A Piecewise Linear Transformation Method based on SPMF and Its Application to Linguistic Approximation (표준 매개변수 소속 함수에 기반을 둔 구간 선형 변환 방법과 언어 근사에의 응용)

  • Choe, Dae-Yeong
    • The KIPS Transactions:PartB
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    • v.8B no.4
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    • pp.351-356
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    • 2001
  • 표준 매개변수 소속 함수(SPMF)에 기반을 둔 구간 선형 변환 방법(PLTM)을 제안한다. 이는 구간 선형 변환 방법을 사용해서 비 매개변수 소속 함수(NPMF)로 표현된 퍼지 집합이 매개변수 소속 함수(PMF)로 표현된 퍼지 집합으로 변환될 수 있다는 생각에서 유래되었다. 이 경우, 이들 매개변수들은 퍼지 집합의 구조를 결정하기 위한 특징점들 이라고 할 수 있다. 결과적으로 구간 선형 변환 방법은 비 매개변수 소속 함수를 매개변수 소속 함수로 변환해 줌으로써 비 매개변수 소속 함수에 기반을 둔 퍼지 시스템과 비교해 볼 때 퍼지 시스템이 상대적으로 빠르게 처리될 수 있게 한다. 한편, 표준 매개변수 소속 함수들의 전형적인 형태가 소개되고 분석된다. 끝으로, PLTM의 전형적인 응용을 제시하고 수치적인 예를 보여준다.

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A nonlinear transformation methods for GMM to improve over-smoothing effect

  • Chae, Yi Geun
    • Journal of Advanced Marine Engineering and Technology
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    • v.38 no.2
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    • pp.182-187
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    • 2014
  • We propose nonlinear GMM-based transformation functions in an attempt to deal with the over-smoothing effects of linear transformation for voice processing. The proposed methods adopt RBF networks as a local transformation function to overcome the drawbacks of global nonlinear transformation functions. In order to obtain high-quality modifications of speech signals, our voice conversion is implemented using the Harmonic plus Noise Model analysis/synthesis framework. Experimental results are reported on the English corpus, MOCHA-TIMIT.

[ $C^1$ ] Continuous Piecewise Rational Re-parameterization

  • Liang, Xiuxia;Zhang, Caiming;Zhong, Li;Liu, Yi
    • International Journal of CAD/CAM
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    • v.6 no.1
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    • pp.59-64
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    • 2006
  • A new method to obtain explicit re-parameterization that preserves the curve degree and parametric domain is presented in this paper. The re-parameterization brings a curve very close to the arc length parameterization under $L_2$ norm but with less segmentation. The re-parameterization functions we used are $C^1$ continuous piecewise rational linear functions, which provide more flexibility and can be easily identified by solving a quadratic equation. Based on the outstanding performance of Mobius transformation on modifying pieces with monotonic parametric speed, we first create a partition of the original curve, in which the parametric speed of each segment is of monotonic variation. The values of new parameters corresponding to the subdivision points are specified a priori as the ratio of its cumulative arc length and its total arc length. $C^1$ continuity conditions are imposed to each segment, thus, with respect to the new parameters, the objective function is linear and admits a closed-form optimization. Illustrative examples are also given to assess the performance of our new method.

A Study on the Extension of Fuzzy Programming Solution Method (Fuzzy 계확법의 해법일반화에 관한 연구)

  • 양태용;김현준
    • Journal of the Korean Operations Research and Management Science Society
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    • v.11 no.1
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    • pp.36-43
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    • 1986
  • In this study, the fuzzy programming is extended to handle various types of membership functions by transformation of the complicated fuzzy programming problems into the equivalent crisp linear programming problems with single objective. It is well-known that the fuzzy programming problem with linear membership functions (i.e., ramp type) can be easily transformed into a linear programming problem by introducing one dummy variable to minimize the worst unwanted deviation. However, until recently not many researches have been done to handle various general types of complicated linear membership functions which might be more realistic than ramp-or triangular-type functions. In order to handle these complicated membership functions, the goal dividing concept, which is based on the fuzzy set operation (i. e., intersection and union operations), has been prepared. The linear model obtained using the goal dividing concept is more efficient and single than the previous models [4, 8]. In addition, this result can be easily applied to any nonlinear membership functions by piecewise approximation since the membership function is continuous and monotone increasing or decreasing.

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A Mixed-Integer Programming Model for Effective Distribution of Relief Supplies in Disaster (재난 구호품의 효과적 분배를 위한 혼합정수계획 모형)

  • Kim, Heungseob
    • Journal of the Society of Korea Industrial and Systems Engineering
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    • v.44 no.1
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    • pp.26-36
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    • 2021
  • The topic of this study is the field of humanitarian logistics for disaster response. Many existing studies have revealed that compliance with the golden time in response to a disaster determines the success or failure of relief activities, and logistics costs account for 80% of the disaster response cost. Besides, the agility, responsiveness, and effectiveness of the humanitarian logistics system are emphasized in consideration of the disaster situation's characteristics, such as the urgency of life-saving and rapid environmental changes. In other words, they emphasize the importance of logistics activities in disaster response, which includes the effective and efficient distribution of relief supplies. This study proposes a mathematical model for establishing a transport plan to distribute relief supplies in a disaster situation. To determine vehicles' route and the amount of relief for cities suffering a disaster, it mainly considers the urgency, effectiveness (restoration rate), and uncertainty in the logistics system. The model is initially developed as a mixed-integer nonlinear programming (MINLP) model containing some nonlinear functions and transform into a Mixed-integer linear programming (MILP) model using a logarithmic transformation and piecewise linear approximation method. Furthermore, a minimax problem is suggested to search for breakpoints and slopes to define a piecewise linear function that minimizes the linear approximation error. A numerical experiment is performed to verify the MILP model, and linear approximation error is also analyzed in the experiment.

Geodesics-based Shape-preserving Mesh Parameterization (직선형 측지선에 기초한 원형보전형 메쉬 파라미터화)

  • 이혜영
    • Journal of KIISE:Computer Systems and Theory
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    • v.31 no.7
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    • pp.414-420
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    • 2004
  • Among the desirable properties of a piecewise linear parameterization, guaranteeing a one-to-one mapping (i.e., no triangle flips in the parameter plane) is often sought. A one-to-one mapping is accomplished by non-negative coefficients in the affine transformation. In the Floater's method, the coefficients were computed after the 3D mesh was flattened by geodesic polar-mapping. But using this geodesic polar map introduces unnecessary local distortion. In this paper, a simple variant of the original shape-preserving mapping technique by Floater is introduced. A new simple method for calculating barycentric coordinates by using straightest geodesics is proposed. With this method, the non-negative coefficients are computed directly on the mesh, reducing the shape distortion introduced by the previously-used polar mapping. The parameterization is then found by solving a sparse linear system, and it provides a simple and visually-smooth piecewise linear mapping, without foldovers.

Invariant Image Matching using Linear Features (선형특징을 사용한 불변 영상정합 기법)

  • Park, Se-Je;Park, Young-Tae
    • Journal of the Korean Institute of Telematics and Electronics S
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    • v.35S no.12
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    • pp.55-62
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    • 1998
  • Matching two images is an essential step for many computer vision applications. A new approach to the scale and rotation invariant scene matching, using linear features, is presented. Scene or model images are described by a set of linear features approximating edge information, which can be obtained by the conventional edge detection, thinning, and piecewise linear approximation. A set of candidate parameters are hypothesized by mapping the angular difference and a new distance measure to the Hough space and by detecting maximally consistent points. These hypotheses are verified by a fast linear feature matching algorithm composed of a single-step relaxation and a Hough technique. The proposed method is shown to be much faster than the conventional one where the relaxation process is repeated until convergence, while providing matching performance robust to the random alteration of the linear features, without a priori information on the geometrical transformation parameters.

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Automatic Registration Between KOMPSAT-2 and TerraSAR-X Images (KOMPSAT-2 영상과 TerraSAR-X 영상 간 자동기하보정)

  • Han, You-Kyung;Byun, Young-Gi;Chae, Tae-Byeong;Kim, Yong-Il
    • Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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    • v.29 no.6
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    • pp.667-675
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    • 2011
  • In this paper, we propose an automatic image-to-image registration between high resolution multi-sensor images. To do this, TerraSAR-X image was shifted according to the initial translation differences of the x and y directions between images estimated using Mutual Information method. After that, the Canny edge operator was applied to both images to extract linear features. These features were used to design a cost function that finds matching points based on the similarities of their locations and gradient orientations. For extracting large number of evenly distributed matching points, only one point within each regular grid constructed throughout the image was extracted to the final matching point pair. The model, which combined the piecewise linear function with the global affine transformation, was applied to increase the accuracy of the geometric correction, and the proposed method showed RMSE lower than 5m in all study sites.

Analysis of Co-registration Performance According to Geometric Processing Level of KOMPSAT-3/3A Reference Image (KOMPSAT-3/3A 기준영상의 기하품질에 따른 상호좌표등록 결과 분석)

  • Yun, Yerin;Kim, Taeheon;Oh, Jaehong;Han, Youkyung
    • Korean Journal of Remote Sensing
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    • v.37 no.2
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    • pp.221-232
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    • 2021
  • This study analyzed co-registration results according to the geometric processing level of reference image, which are Level 1R and Level 1G provided from KOMPSAT-3 and KOMPSAT-3A images. We performed co-registration using each Level 1R and Level 1G image as a reference image, and Level 1R image as a sensed image. For constructing the experimental dataset, seven Level 1R and 1G images of KOMPSAT-3 and KOMPSAT-3A acquired from Daejeon, South Korea, were used. To coarsely align the geometric position of the two images, SURF (Speeded-Up Robust Feature) and PC (Phase Correlation) methods were combined and then repeatedly applied to the overlapping region of the images. Then, we extracted tie-points using the SURF method from coarsely aligned images and performed fine co-registration through affine transformation and piecewise Linear transformation, respectively, constructed with the tie-points. As a result of the experiment, when Level 1G image was used as a reference image, a relatively large number of tie-points were extracted than Level 1R image. Also, in the case where the reference image is Level 1G image, the root mean square error of co-registration was 5 pixels less than the case of Level 1R image on average. We have shown from the experimental results that the co-registration performance can be affected by the geometric processing level related to the initial geometric relationship between the two images. Moreover, we confirmed that the better geometric quality of the reference image achieved the more stable co-registration performance.

Automatic Liver Segmentation of a Contrast Enhanced CT Image Using a Partial Histogram Threshold Algorithm (부분 히스토그램 문턱치 알고리즘을 사용한 조영증강 CT영상의 자동 간 분할)

  • Kyung-Sik Seo;Seung-Jin Park;Jong An Park
    • Journal of Biomedical Engineering Research
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    • v.25 no.3
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    • pp.189-194
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    • 2004
  • Pixel values of contrast enhanced computed tomography (CE-CT) images are randomly changed. Also, the middle liver part has a problem to segregate the liver structure because of similar gray-level values of a pancreas in the abdomen. In this paper, an automatic liver segmentation method using a partial histogram threshold (PHT) algorithm is proposed for overcoming randomness of CE-CT images and removing the pancreas. After histogram transformation, adaptive multi-modal threshold is used to find the range of gray-level values of the liver structure. Also, the PHT algorithm is performed for removing the pancreas. Then, morphological filtering is processed for removing of unnecessary objects and smoothing of the boundary. Four CE-CT slices of eight patients were selected to evaluate the proposed method. As the average of normalized average area of the automatic segmented method II (ASM II) using the PHT and manual segmented method (MSM) are 0.1671 and 0.1711, these two method shows very small differences. Also, the average area error rate between the ASM II and MSM is 6.8339 %. From the results of experiments, the proposed method has similar performance as the MSM by medical Doctor.