• 제목/요약/키워드: Error Minimization

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Object Tracking Based on Exactly Reweighted Online Total-Error-Rate Minimization (정확히 재가중되는 온라인 전체 에러율 최소화 기반의 객체 추적)

  • JANG, Se-In;PARK, Choong-Shik
    • Journal of Intelligence and Information Systems
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    • v.25 no.4
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    • pp.53-65
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    • 2019
  • Object tracking is one of important steps to achieve video-based surveillance systems. Object tracking is considered as an essential task similar to object detection and recognition. In order to perform object tracking, various machine learning methods (e.g., least-squares, perceptron and support vector machine) can be applied for different designs of tracking systems. In general, generative methods (e.g., principal component analysis) were utilized due to its simplicity and effectiveness. However, the generative methods were only focused on modeling the target object. Due to this limitation, discriminative methods (e.g., binary classification) were adopted to distinguish the target object and the background. Among the machine learning methods for binary classification, total error rate minimization can be used as one of successful machine learning methods for binary classification. The total error rate minimization can achieve a global minimum due to a quadratic approximation to a step function while other methods (e.g., support vector machine) seek local minima using nonlinear functions (e.g., hinge loss function). Due to this quadratic approximation, the total error rate minimization could obtain appropriate properties in solving optimization problems for binary classification. However, this total error rate minimization was based on a batch mode setting. The batch mode setting can be limited to several applications under offline learning. Due to limited computing resources, offline learning could not handle large scale data sets. Compared to offline learning, online learning can update its solution without storing all training samples in learning process. Due to increment of large scale data sets, online learning becomes one of essential properties for various applications. Since object tracking needs to handle data samples in real time, online learning based total error rate minimization methods are necessary to efficiently address object tracking problems. Due to the need of the online learning, an online learning based total error rate minimization method was developed. However, an approximately reweighted technique was developed. Although the approximation technique is utilized, this online version of the total error rate minimization could achieve good performances in biometric applications. However, this method is assumed that the total error rate minimization can be asymptotically achieved when only the number of training samples is infinite. Although there is the assumption to achieve the total error rate minimization, the approximation issue can continuously accumulate learning errors according to increment of training samples. Due to this reason, the approximated online learning solution can then lead a wrong solution. The wrong solution can make significant errors when it is applied to surveillance systems. In this paper, we propose an exactly reweighted technique to recursively update the solution of the total error rate minimization in online learning manner. Compared to the approximately reweighted online total error rate minimization, an exactly reweighted online total error rate minimization is achieved. The proposed exact online learning method based on the total error rate minimization is then applied to object tracking problems. In our object tracking system, particle filtering is adopted. In particle filtering, our observation model is consisted of both generative and discriminative methods to leverage the advantages between generative and discriminative properties. In our experiments, our proposed object tracking system achieves promising performances on 8 public video sequences over competing object tracking systems. The paired t-test is also reported to evaluate its quality of the results. Our proposed online learning method can be extended under the deep learning architecture which can cover the shallow and deep networks. Moreover, online learning methods, that need the exact reweighting process, can use our proposed reweighting technique. In addition to object tracking, the proposed online learning method can be easily applied to object detection and recognition. Therefore, our proposed methods can contribute to online learning community and object tracking, detection and recognition communities.

An Error-Bounded B-spline Fitting Technique to Approximate Unorganized Data (무작위 데이터 근사화를 위한 유계오차 B-스플라인 근사법)

  • Park, Sang-Kun
    • Korean Journal of Computational Design and Engineering
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    • v.17 no.4
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    • pp.282-293
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    • 2012
  • This paper presents an error-bounded B-spline fitting technique to approximate unorganized data within a prescribed error tolerance. The proposed approach includes two main steps: leastsquares minimization and error-bounded approximation. A B-spline hypervolume is first described as a data representation model, which includes its mathematical definition and the data structure for implementation. Then we present the least-squares minimization technique for the generation of an approximate B-spline model from the given data set, which provides a unique solution to the problem: overdetermined, underdetermined, or ill-conditioned problem. We also explain an algorithm for the error-bounded approximation which recursively refines the initial base model obtained from the least-squares minimization until the Euclidean distance between the model and the given data is within the given error tolerance. The proposed approach is demonstrated with some examples to show its usefulness and a good possibility for various applications.

Error Minimization of Angular Velocity using Encoders and Gyro (엔코더와 자이로를 이용한 각속도 오차 최소화)

  • Kim, Jung-Min;Do, Joo-Cheol;Kim, Sung-Shin
    • Journal of the Korean Institute of Intelligent Systems
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    • v.20 no.6
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    • pp.814-819
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    • 2010
  • This paper is presented to study the error minimization of angular velocity for AGV(autonomous ground vehicle). The error minimization of angular velocity is related to localization technique which is the most important technique for autonomous vehicle. Accelerometer, yaw gyro and electronic compass have been used to measure angular velocity. And methods for error minimization of angular velocity have been actively studied through probabilistic methods and sensor fusion for AGVs. However, those sensors still occure accumulated error by mathematical error, system characters of each sensor, and computational cost are increased greatly when several sensor are used to correct accumulated error. Therefore, this paper studies about error minimization of angular velocity that just uses encoder and gyro. To experiment, we use autonomous vehicle which is made by ourselves. In experimental result, we verified that the localization error of proposed method has even less than the localization errors which we just used encoder and gyro respectively.

A method to extract the aspherical surface equation from the unknown ophthalmic lens (형상 분석에 의한 안경렌즈의 비구면 계수 추출 방법)

  • 이호철;이남영;김건희;송창규
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2004.10a
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    • pp.430-433
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    • 2004
  • The ophthalmic lens manufacturing processes need to extract the aspherical surface equation from the unknown surface since its real profile can be adjusted by the process variables to make the ideal curve without the optical aberration. This paper presents a procedure to get the aspherical surface equation of an aspherical ophthalmic lens. Aspherical form generally consists of the Schulz formula to describe its profile. Therefore, the base curvature, conic constant, and high-order polynomial coefficient should be set to the original design equation. To find an estimated aspherical profile, firstly lens profile is measured by a contact profiler, which has a sub-micrometer measurement resolution. A mathematical tool is based on the minimization of the error function to get the estimated aspherical surface equation from the scanned aspherical profile. Error minimization step uses the Nelder-Mead simplex (direct search) method. The result of the refractive power measurement is compared with the curvature distribution on the estimated aspherical surface equation

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The Sound Field Reconstruction of a Korean Bell Using an Error Minimization Scheme in the BEM-Based Acoustical Holography (경계요소법에 기초한 음향 홀로그래피에서 오차 최소화 과정에 의한 한국 종의 음장 재구성)

  • 김철희;이장무;강연준
    • Journal of KSNVE
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    • v.9 no.1
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    • pp.131-140
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    • 1999
  • A method to reconstruct the sound field around a Korean bell is developed. The sound radiation problem is formulated based on the boundary element method by using the algorithm of the acoustical holography. Sound pressures at the hologram surface are measured and used as input data for the analysis program that was developed in this study. An error minimization scheme is presented to overcome difficulties that arise in the backward reconstruction of the BEM-based acoustical holography In the model fictitious source surfaces were also introduced to reduce the complexity stemmed from the source shape. The sound field associated with the (4.0) vibrational mode of the Korean bell was visualized and verified experimentally.

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Estimation Method of the Best-Approximated Form Factor Using the Profile Measurement of the Aspherical Ophthalmic Lens (단면 형상 측정을 이용한 비구면 안경 렌즈의 최적 근사화된 설계 계수의 추정 방법)

  • Lee Hocheol
    • Journal of the Korean Society for Precision Engineering
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    • v.22 no.5 s.170
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    • pp.55-62
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    • 2005
  • This paper presents mainly a procedure to get the mathematical form of the manufactured aspherical lens. Generally Schulz formula describes the aspherical lens profile. Therefore, the base curvature, conic constant. and high-order polynomial coefficient should be set to get the approximated design equation. To find the best-approximated aspherical form, lens profile is measured by a commercial stylus profiler, which has a sub-micrometer measurement resolution. The optimization tool is based on the minimization of the root mean square of error sum to get the estimated aspherical surface equation from the scanned aspherical profile. Error minimization step uses the Nelder-Mead simplex (direct search) method. The result of the lens refractive power measurement shows the experimental consistency with the curvature distribution of the best-approximated aspherical surface equation

Design of suboptimal robust kalman filter using LMI approach (LMI기법을 이용한 준최적 강인 칼만 필터의 설계)

  • 진승희;윤태성;박진배
    • 제어로봇시스템학회:학술대회논문집
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    • 1997.10a
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    • pp.1477-1480
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    • 1997
  • This paper is concerned with the design of a suboptimal robust Kalman filter using LMI approach for system models in the state space, which are subjected to parameter uncertainties in both the state and measurement atrices. Under the assumption that augmented system composed of the uncertain system and the state estimation error dynamics should be stable, a Lyapunov inequality is obtained. And from this inequaltiy, the filter design problem can be transformed to the gneric LMI problems i.e., linear objective minimization problem and generalized eigenvalue minimization problem. When applied to uncertain linear system modles, the proposed filter can provide the minimum upper bound of the estimation error variance for all admissible parameter uncertainties.

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Decision of Modulation Index of Current-Source TPWM Inverter for Minimization of Speed Ripple and Position Error (속도맥동 및 위치오차를 최소로 하는 전류원 TPWM 인버터의 변조도 결정)

  • 구본호;권우현;김수중
    • Journal of the Korean Institute of Telematics and Electronics
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    • v.26 no.11
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    • pp.1819-1828
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    • 1989
  • In this paper, we determined the modulation index for minimization of speed ripple and position error using maximum speed ripple (SRF) and maximum position error(PEF) in current source TPWM inverter. Through computer simulation, we compared with total current harmonic distortion, SRF and PEF for square wave modulation method and TPWM method. As a result, it turns out that square wave modulation method is superior to TPWM method of 3 pulses per half cycle in speed ripple and position error contents. And TPWM is better than square wave method when pulse number is more than 5. Also, in these pulse numbers, moduladtion index of minimum speed ripple and munimum position error is 0.91.

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Detection of tonal frequency of underwater radiated noise via atomic norm minimization (Atomic norm minimization을 통한 수중 방사 소음 신호의 토널 주파수 탐지)

  • Kim, Junhan;Kim, Jinhong;Shim, Byonghyo;Hong, Jungpyo;Kim, Seongil;Hong, Wooyoung
    • The Journal of the Acoustical Society of Korea
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    • v.38 no.5
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    • pp.543-548
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    • 2019
  • The tonal signal caused by the machinery component of a vessel such as an engine, gearbox, and support elements, can be modeled as a sparse signal in the frequency domain. Recently, compressive sensing based techniques that recover an original signal using a small number of measurements in a short period of time, have been applied for the tonal frequency detection. These techniques, however, cannot avoid a basis mismatch error caused by the discretization of the frequency domain. In this paper, we propose a method to detect the tonal frequency with a small number of measurements in the continuous domain by using the atomic norm minimization technique. From the simulation results, we demonstrate that the proposed technique outperforms conventional methods in terms of the exact recovery ratio and mean square error.

Quantitative Evaluation of Sparse-view CT Images Obtained with Iterative Image Reconstruction Methods (반복적 연산으로 얻은 Sparse-view CT 영상에 대한 정량적 평가)

  • Kim, H.S.;Gao, Jie;Cho, M.H.;Lee, S.Y.
    • Journal of Biomedical Engineering Research
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    • v.32 no.3
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    • pp.257-263
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    • 2011
  • Sparse-view CT imaging is considered to be a solution to reduce x-ray dose of CT. Sparse-view CT imaging may have severe streak artifacts that could compromise the image qualities. We have compared quality of sparseview images reconstructed with two representative iterative reconstruction techniques, SIRT and TV-minimization, in terms of image error and edge preservation. In the comparison study, we have used the Shepp-Logan phantom image and real CT images obtained with a micro-CT. In both phantom image and real CT image tests, TV-minimization technique shows the best performance in error reduction and preserving edges. However, the excessive computation time of TV-minimization is a technical challenge for the practical use.