• 제목, 요약, 키워드: Parameter

검색결과 21,588건 처리시간 0.072초

FATIGUE DAMAGE PARAMETER OF SPOT WELDED JOINTS UNDER PROPORTIONAL LOADING

  • KANG H. T.
    • International Journal of Automotive Technology
    • /
    • v.6 no.3
    • /
    • pp.285-291
    • /
    • 2005
  • In this paper, the author proposes a fatigue damage parameter of spot welded joints under proportional loading. The proposed fatigue damage parameter is developed based on von Mises' equivalent stress and local structural stress at the edge of spot weld nugget. The structural stress at the edges of the weld nugget in each sheet is calculated using the forces and moments that are determined by finite element analysis. A structural equivalent stress is then calculated by von Mises' equivalent stress equation. The structural equivalent stresses are correlated to experimental fatigue life of the spot welded joints. The proposed parameter is evaluated with fatigue test data of spot welds subjected to multi axial and tensile-shear loads. Sheppard's parameter and Rupp and co-workers' parameter are also evaluated with the same test data to compare with the author's parameter. This proposed parameter presents a better correlation with experimental fatigue data than those of Sheppard's and Rupp and co-workers' parameter. The proposed parameter should be very effective for durability calculations during the early design phase since coarsely meshed finite element models can be employed.

Estimation on a two-parameter Rayleigh distribution under the progressive Type-II censoring scheme: comparative study

  • Seo, Jung-In;Seo, Byeong-Gyu;Kang, Suk-Bok
    • Communications for Statistical Applications and Methods
    • /
    • v.26 no.2
    • /
    • pp.91-102
    • /
    • 2019
  • In this paper, we propose a new estimation method based on a weighted linear regression framework to obtain some estimators for unknown parameters in a two-parameter Rayleigh distribution under a progressive Type-II censoring scheme. We also provide unbiased estimators of the location parameter and scale parameter which have a nuisance parameter, and an estimator based on a pivotal quantity which does not depend on the other parameter. The proposed weighted least square estimator (WLSE) of the location parameter is not dependent on the scale parameter. In addition, the WLSE of the scale parameter is not dependent on the location parameter. The results are compared with the maximum likelihood method and pivot-based estimation method. The assessments and comparisons are done using Monte Carlo simulations and real data analysis. The simulation results show that the estimators ${\hat{\mu}}_u({\hat{\theta}}_p)$ and ${\hat{\theta}}_p({\hat{\mu}}_u)$ are superior to the other estimators in terms of the mean squared error (MSE) and bias.

Penalized Likelihood Regression with Negative Binomial Data with Unknown Shape Parameter

  • Kim, Young-Ju
    • Communications for Statistical Applications and Methods
    • /
    • v.14 no.1
    • /
    • pp.23-32
    • /
    • 2007
  • We consider penalized likelihood regression with data from the negative binomial distribution with unknown shape parameter. Smoothing parameter selection and asymptotically efficient low dimensional approximations are employed for negative binomial data along with shape parameter estimation through several different algorithms.

데이터베이스 시스템 성능 향상을 위한 데이터베이스 관리 시스템 파라미터 튜닝 프로세스 (Database Management System Parameter Tuning Processes for Improving Database System Performance)

  • 최용락;윤병권;정기원
    • 한국전자거래학회지
    • /
    • v.7 no.1
    • /
    • pp.107-127
    • /
    • 2002
  • Database system parameter tuning is one of database system tuning that achieve to improve performance of database system with application program tuning and data model tuning. By parameter tuning adjusts value of entry that is staled in data dictionary's parameter file that is included to database system, it is thing which make relevant database system can display performance of most suitable. And, it is that achievement is one o( possible tuning method immediately without occurrence of additional expense or involved hardware for database system performance elevation and ashes composition of software. But, it is actuality that administration about parameter practical use is not achieved, and is using Default Value of parameter that database management system offers just as it is systematically. So, this paper presents parameter tuning process that can :achieve Parameter tuning of database system that is operating present systematically, and parameter tuning process each activity important input urea and tuning achievement product. And explain about effect and result that happen by sort database system performance and parameters that it is affinity systematically, and grasp relationships between parameter, and change parameter of string database system. And not that parameter uses contents that specify by fixing when establish database administration system, is going to emphasize and explain that must utilize changing continuously during database system operation. It changes parameter entry value how in various kinds different operation environment and present if must apply, and will arrange effect that this parameter enoy value alteration gets in performance liking into account point that is actuality that is using parameter that define database administrators when install the database system just as it is continually without alteration.

  • PDF

매개변수 개념의 교수-학습에 관한 연구 (A Study on the Teaching-Learning of Parameter Concept)

  • 김남희
    • 대한수학교육학회지:수학교육학연구
    • /
    • v.14 no.3
    • /
    • pp.305-325
    • /
    • 2004
  • 본 논문은 학교수학에서 다루어지고 있는 매개변수 개념의 교수-학습에 관한 논의이다. 우리나라 수학교과서에서 매개변수 개념은 중학교 수준의 학습내용과 관련된 대수적 표현에서 자주 다루어지고 있음에도 불구하고 그 개념에 대한 용어 정의는 고등학교 선택교육과정 교과서에서 비로소 도입되고 있기 때문에 매개변수개념 이해를 위한 수학교사의 교수학적 노력이 요망된다. 본 논문에서는 학교현장에서 매개변수 개념의 지도를 위한 교수학적 시사점을 이끌어 내기 위해 매개변수의 개념 정의를 분석하고 우리나라 수학과 교육과정상에서 매개변수가 도입되는 맥락을 외국의 사례와 비교해서 검토한다. 또한 선행연구를 통해 대수학습의 관점에서 매개변수 개념 이해의 중요성을 확인하고 매개변수 개념이 학교수학에서 의미 있게 다루어져야 할 학습맥락에 대해 논의해 본다. 마지막으로 본 논문의 연구내용을 종합하여 매개변수 개념의 교수-학습을 위한 시사점을 요약하여 제시한다.

  • PDF

Design of a Robust Target Tracker for Parameter Variations and Unknown Inputs

  • Kim, Eung-Tai;Andrisani, D. II
    • International Journal of Aeronautical and Space Sciences
    • /
    • v.2 no.2
    • /
    • pp.73-81
    • /
    • 2001
  • This paper describes the procedure to develop a robust estimator design method for a target tracker that accounts for both structured real parameter uncertainties and unknown inputs. Two robust design approaches are combined: the Mini-p-Norm. design method to consider real parameter uncertainties and the $H_{\infty}$ design technique for unknown disturbances and unknown inputs. Constant estimator gains are computed that guarantee the robust performance of the estimator in the presence of parameter variations in the target model and unknown inputs to the target. The new estimator has two design parameters. One design parameter allows the trade off between small estimator error variance and low sensitivity to unknown parameter variations. Another design parameter allows the trade off between the robustness to real parameter variations and the robustness to unknown inputs. This robust estimator design method was applied to the longitudinal motion tracking problem of a T-38 aircraft.

  • PDF

Acquisition of English Complex Predicates in SLA

  • Park, Hye-Son
    • 영어어문교육
    • /
    • v.12 no.2
    • /
    • pp.177-194
    • /
    • 2006
  • Snyder (2001) proposes that complex predicate constructions are interrelated by shared dependence on a single parameter, the Compounding Parameter, and that the global application of the parameter explains the simultaneous acquisition of the complex predicate constructions and N-N compounds in L1 acquisition of English. Slabakova (2002) examined the status of the Compounding Parameter in the acquisition of L2 Spanish by instructed learners. The result of the study, however, was not compatible with the prediction of the Compounding Parameter, possibly due to the availability of negative evidence in the input. Building upon Slabakova's study, this paper examines the status of the Compounding Parameter in naturalistic L2 learning. It is shown that the naturalistic L2 learners do not acquire the complex predicate constructions and N-N compounds concurrently contra to the prediction of the Compounding Parameter. It is suggested that the validity of the Compounding Parameter as a theoretical construct be reconsidered.

  • PDF

Coprime Factor Reduction of Parameter Varying Controller

  • Saragih, Roberd;Widowati, Widowati
    • International Journal of Control, Automation, and Systems
    • /
    • v.6 no.6
    • /
    • pp.836-844
    • /
    • 2008
  • This paper presents an approach to order reduction of linear parameter varying controller for polytopic model. Feasible solutions which satisfy relevant linear matrix inequalities for constructing full-order parameter varying controller evaluated at each polytopic vertices are first found. Next, sufficient conditions are derived for the existence of a right coprime factorization of parameter varying controller. Furthermore, a singular perturbation approximation for time invariant systems is generalized to reduce full-order parameter varying controller via parameter varying right coprime factorization. This generalization is based on solutions of the parameter varying Lyapunov inequalities. The closed loop performance caused by using the reduced order controller is developed. To examine the performance of the reduced-order parameter varying controller, the proposed method is applied to reduce vibration of flexible structures having the transverse-torsional coupled vibration modes.

Estimation of Gini Index of the Exponential Distribution by Bootstrap Method

  • Kang, Suk-Bok;Cho, Young-Suk
    • Communications for Statistical Applications and Methods
    • /
    • v.3 no.3
    • /
    • pp.291-297
    • /
    • 1996
  • In this paper, we propose the jackknife estimator and the bootstrap estimator of Gini index of the two-parameter exponential distribution when the location parameter $\theta$ is unknown and the scale parameter $\sigma$is known. Sinilarly, we propose the bias location parameter $\theta$ and the scale parameter $\sigma$ are unknown. The bootstrap estimator is more efficient than the other estimators when the location parameter $\theta$is unknown and the scale parameter $\sigma$ is known, and the bias corrected estimator is more efficient than the MLE when both the location parameter $\theta$ and the scale parameter $\sigma$are unknown.

  • PDF