• Title/Summary/Keyword: Minimization Technique

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The Prediction of Fatigue Life According to the Determination of the Parameter in Residual Strength Degradation Model (잔류강도 저하모델의 파라미터결정법에 따른 피로수명예측)

  • 김도식;김정규
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.18 no.8
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    • pp.2053-2061
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    • 1994
  • The static and fatigue tensile tests have been conduted to predict the fatigue life of 8-harness satin woven and plain woven carbon/epoxy composite plates containing a circular hole. A fatigue residual strength degradation model, based on the assumption that the residual strength for unnotched specimen decreases monotonically, has been applied to predict statistically the fatigue life of materials used in this study. To determine the parameters(c, b and K) of the residual strength degradation model, the minimization technique and the maximum likelihood method are used. Agreement of the converted ultimate strength by using the minimization technique with the static ultimate strength is reasonably good. Therefore, the minimization technique is more adjustable in the determination of the parameter and the prediction of the fatigue life than the maximum likelihood method.

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.

A Proposal of parameter Determination Method in the Residual Strength Degradation Model for the Prediction of Fatigue Life(II) (피로수명예측을 위한 잔류강도 저하모델의 파라미터 결정법 제안(II))

  • Kim, Sang-Tae;Jang, Seong-Su
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.25 no.9
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    • pp.1452-1460
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    • 2001
  • A new method of parameter determination in the fatigue residual strength degradation model is proposed. The new method and minimization technique is compared experimentally to account for the effect of tension-compression fatigue loading of spheroidal graphite cast iron and graphite/epoxy laminate. It is shown that the correlation between the experimental results and the theoretical prediction on the fatigue life and residual strength distribution using the proposed method is very reasonable. Therefore, the proposed method is more adjustable in the determination of the parameter than minimization technique for the prediction of the fatigue characteristics.

Detent Force Minimization Techniques in Permanent Magnet Linear Synchronous Motor (영구자석 선형동기전동기의 디텐트력 저감법)

  • Lim, Ki-Chae;Woo, Joon-Keun;Hong, Jung-Pyo;Kim, Gyu-Tak
    • The Transactions of the Korean Institute of Electrical Engineers B
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    • v.49 no.11
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    • pp.749-756
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    • 2000
  • Detent force develops generally undesirable effect that contributes to the output ripple of machine, vibration and noise. This paper proposes detent force minimization techniques for a Permanent Magnet Linear Synchronous Motor (PMLSM). In addition, thrust according to each minimization technique is estimated to observe the change of machine performance. A two-dimensional Finite Element Method is used to predict detent force and thrust due to structural factors and non-linearity. And moving node technique for geometric models is proposed to reduce modeling time and efforts.

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A Study on the Current Minimization of a Outer-Rotor Type BLDC Motor for Low Voltage Application (저전압용 외전형 BLDC 전동기의 소비전류 최소화에 대한 연구)

  • Kim, Han-Deul;Chung, Gyo-Bum;Shin, Pan Seok
    • Journal of the Korea Institute of Military Science and Technology
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    • v.21 no.2
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    • pp.211-216
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    • 2018
  • This paper presents a numerical optimization technique and switching phase control technique aiming at improvement of efficiency of the low voltage BLDC motor. The optimization technique is performed using the generalized sensitivity technique, response surface method(RSM) and sampling minimization technique. In order to minimize current consumption of the BLDC motor, the switching method of the driving device is optimized using RSM with finite element analysis. The ratings of BLDC motor are 50 W, 24 V, 1200 rpm. As optimizing results, the input current is reduced from 2.78 to 2.51 [A] when the switching phase is shifted by -2.65 [DEG_ELC] at the rated driving speed of 1200 [rpm]. It is confirmed that the proposed method reduces the consuming current of the low voltage BLDC motor through switching phase control method using the numerical optimization method.

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.

A Low Power scan Design Architecture (저전력을 고려한 스캔 체인 구조 변경)

  • Min, Hyoung-Bok;Kim, In-Soo
    • The Transactions of the Korean Institute of Electrical Engineers D
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    • v.54 no.7
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    • pp.458-461
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    • 2005
  • Power dissipated during test application is substantially higher than power dissipated during functional operation which can decrease the reliability and lead to yield loss. This paper presents a new technique for power minimization during test application in full scan sequential circuits. This paper shows freezing of combinational logic parts during scan shift operation in test mode. The freezing technique leads to power to minimization. Significant power reduction in the scan techniques is achieved on ISCAS 89 benchmarks.

Trajectory planning for redundant robot by joint disturbance torque minimization (여유자유도 로봇의 관절외란최소화를 이용한 궤적계획)

  • 최명환;최병진
    • 제어로봇시스템학회:학술대회논문집
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    • 1997.10a
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    • pp.1581-1584
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    • 1997
  • This paper poropsed an efficient optimization technuque to resolve redundancy and a trajectory planning for a high precision control using proposed optimization technique. The proposed techniqus is the joint disturbance torque optimizatioin considering redundancy in the joing servo control. Joint disturbance torque is not unknown it is described dynamic equation ignored friction and viscosity. The proposed technique is used the dynamic equatiion included the joint disturbance torque characteristics. Numerical example of 3 joint planar redundant robot manipulator is simulated. In the 2-norm minimization of joint disturbance torque we compared pseudoinverse local optimization with proposed technique, and the results showed better the proposed technique. So the proposed technique can be highly precision controlled redundant robot manipulators in the joint servo control.

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Minimization of Fuel Cost by Optimal Generation (연료비 최소화를 위한 유무효 발전력 분담)

  • 이상중
    • Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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    • 2003.11a
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    • pp.289-290
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    • 2003
  • This paper gives a method for the minimization of the fuel cost by optimal generation. Derivation of the sensitivity of system loss by optimization technique is introduced and the loss sensitivities are substituted into the optimality conditions to obtain the minimized fuel cost.

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Analysis of the Logic Minimization in the Design of 74LS49 and 74LS47 BCD-to-Seven-Segment Decoders (74LS49와 74LS49의 디자인에 사용된 로직최소화에 대한 분석)

  • You, Jun-Bok;Chung, Tea-Sang
    • Proceedings of the KIEE Conference
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    • 1999.11c
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    • pp.784-787
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    • 1999
  • The 74LS49 and 74LS47 chips are MSI circuits and are used for decoding the BCD input and driving seven-segment displays. The logic of these chips are often used not only as component chips in the commercial digital systems, but are used as library components in fairly complicated ASIC designs. Thus, the understanding of the logic characteristics of these chips is beneficial for future applications. It was analyzed reversely that the design of these chips includes a special logic minimization technique, which neither documented nor reported. This paper is to analyze the function of the logic and the special minimization technique adapted in the design of 74LS49 and 74LS47 chips.

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