• Steel and Composite Structures
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• 제34권4호
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• pp.599-613
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• 2020

In this article, free vibration attributes of double-walled carbon nanotubes based on nonlocal elastic shell model have been investigated. For this purpose, a nonlocal Flügge shell model is established to observe the small scale effect. The wave propagation is employed to frame the governing equations as eigenvalue system. The influence of nonlocal parameter subjected to different end supports has been overtly examined. A suitable choice of material properties and nonlocal parameter been focused to analyze the vibration characteristics. The new set of inner and outer tubes radii investigated in detail against aspect ratio and length. The dominance of boundary conditions via nonlocal parameter is shown graphically. The results generated furnish the evidence regarding applicability of nonlocal shell model and also verified by earlier published literature.

• 자동차안전학회지
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• 제13권4호
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• pp.33-38
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• 2021

This paper presents a comparative study between the parameter-optimized Pacejka model and artificial neural network model for the tire force estimation. The two different approaches are investigated and compared in this study. First, offline optimization is conducted based on Pacejka Magic Formula model to determine the proper parameter set for the minimization of tire force error between the model and test data set. Second, deep neural network model is used to fit the model to the tire test data set. The actual tire forces are measured using MTS Flat-Track test platform and the measurements are used as the reference tire data set. The focus of this study is on the applicability of machine learning technique to tire force estimation. It is shown via the regression results that the deep neural network model is more effective in describing the tire force than the parameter-optimized Pacejka model.

• 대한교통학회지
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• 제32권6호
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• pp.662-674
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• 2014

본 연구는 전국 8개 권역(경기, 강원, 충남, 충북, 전남, 전북, 경남, 경북)에 4차로 이상도로(다차로 도로)구간 약 780km(4,372개구간)의 기하구조, 안전시설물, 교통량 및 기상, 토지이용, 도로설계기준 만족여부 등의 변수를 수집하여 사고건수 예측모형을 구축하였다. 모형은 고정모수 모형(fixed parameter model)과 확률모수 모형(random parameter model)을 사용하였다. 확률 모수 음이항 모형의 경우에 계수가 고정된 것이 아닌 특정확률을 가지고 범위로 표현함으로써 부호가 반대가 되는 경우도 일부 나타났다. 고정모수의 음이항 모형은 독립변수가 사고건수에 미치는 영향을 모든 구간에서 하나의 계수로 해석할 수 밖에 없었으나, 확률모수를 이용한 음이항 모형에서는 더욱 다양한 해석이 가능하였다. 특히, 곡선반경, 길 어깨 확보유무, 종단경사 설계기준 만족유무는 특정확률을 가지고 양의영향과 음의영향이 모두 나타났다. 이러한 현상은 모든 구간에서 일률적으로 사고건수 증감에 영향을 미친다기 보다는 일부구간에서는 운전자의 행동특성, 도로구간의 특성에 따라서 반대의 효과가 나타나기도 하는 것을 의미한다.

• Communications for Statistical Applications and Methods
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• 제25권4호
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• pp.355-371
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• 2018

The two parameter negative exponential distribution has many practical applications in queuing theory such as the service times of agents in system, the time it takes before your next telephone call, the time until a radioactive practical decays, the distance between mutations on a DNA strand, and the extreme values of annual snowfall or rainfall; consequently, has many applications in reliability systems. This paper considers an estimation problem of stress-strength model with two parameter negative parameter exponential distribution. We introduce a maximum penalized likelihood method, Bayes estimator using Lindley approximation to estimate stress-strength model and compare the proposed estimators with regular maximum likelihood estimator for complete data. We also introduce a maximum penalized likelihood method, Bayes estimator using a Markov chain Mote Carlo technique for incomplete data. A Monte Carlo simulation study is performed to compare stress-strength model estimates. Real data is used as a practical application of the proposed model.

• 반도체디스플레이기술학회지
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• 제22권1호
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• pp.54-58
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• 2023

In this study, we compared the detection accuracy of the parameters of the scaffold failure detection model. A detection algorithm based on convolutional neural network was used to construct a failure detection model for scaffold. The parameter properties of the model were changed and the results were quantitatively verified. The detection accuracy of the model for each parameter was compared and the parameter with the highest accuracy was identified. We found that the activation function has a significant impact on the detection accuracy, which is 98% for softmax.

• 한국지진공학회논문집
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• 제5권4호
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• pp.27-38
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• 2001

반무한 호소의 동적 모델링을 위한 역학적 집중변수모델을 제안하였다. 깊이가 일정한 2차원 반무한 호소의 전달경계의 정해를 구하였다. 정해의 거동특성을 주파수 영역과 시간 영역에서 조사하였다. 고유진동수와 합성곱 적분의 핵함수인 베셀 함수의 모양 등과 같은 해의 주요 특성이 변하지 않도록 질량, 감쇠기, 스프링 계수를 구한다. 최종 집중 변수 모델은 각각의 고유값에 대해 2개의 질량, 1개의 스프링, 2개의 감쇠기로 구성된다. 적용 예제를 통하여 새로운 집중변수모델이 댐-호소계의 시간 영역 해석에 효율적으로 사용될 수 있음을 확인하였다.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• 제4B권4호
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• pp.206-210
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• 2004

This paper deals with a parameter estimation of the DC-DC converter system for its diagnosis. Especially, we present the results of parameter estimation for the DC-DC converter model by the system identification method. The parameter estimation for the DC-DC converter system aims at the diagnosis of its operating status. For the operating status diagnosis of the DC-DC converter system, we assume that the DC-DC converter system is an equivalent model of the Buck converter and estimate the main parameter for on-line diagnosis. In addition, for verification of an estimated parameter, we compare a bode plot of the estimated system transfer function and measurement results of the HP4194 instrument. It is a control system analyzer for system transfer function measurement. Our results confirm that the main parameter for diagnosis of the DC-DC converter system can be estimated by the system identification method and that the aging status of the system can be predicted by these results on operating status.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2000년도 추계 학술발표회 논문집 Proceedings of EESK Conference-Fall 2000
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• pp.143-150
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• 2000

A physical lumped parameter model is proposed for the time domain analysis of dam-reservoir system. The exact solution of transmitting boundary is derived for a semi-infinite 2-D reservoir of constant depth. The characteristics of the solution are examined in both frequency and the domains. Mass and damping coefficient are obtained from asymptotic behavior of the frequency domain solution. Further refinement to the lumped model is made by approximating the kernel function of the convolution integral in the exact solution. Finally a new physical lumped parameter model is proposed that consists of two masses, a spring and two dampers for each mode. It is demonstrated that new lumped parameter model of transmitting boundary can give excellent results.

• 한국환경과학회지
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• 제16권5호
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• pp.623-632
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• 2007

The objective of this study is analysis of Andong-Dam lake water quality with water quality model. Model parameters of the WASP applied to Lake Andong-Dam were estimated. The methodology is based on grouping water quality constituents and relevant parameters and successively estimating parameters by a trial-and-error procedure. Water qualify system for modeling consisted of BOD, DO, T-N, T-P. The results of water quality modelling using WASP. T-N was maximum affected by K71C(Organic nitrogen mineralization rate) parameter. T-P was maximum affected by K83C(Dissolved organic phosphorus mineralization) parameter, and It did not show a difference almost from the parameter of others and it omitted. BOD was maximum affected by Temperature parameter, it was visible of the reaction due to the KDC(Deoxygenation rate) in afterwords, and it did not show a difference from the parameter of others and it omitted. DO was maximum affect by Temperature parameter, and It did not show a difference almost from the parameter of others and it omitted. The parameter which it presumes from the this study uses a water quality modeling and Actual value and the result with which it compares, error rate the parameter presumption which is appropriate with 1% interior and exterior is investigated, It will reach and it uses and it will be able to apply to the suitable parameter in water quality modelling of the objective area which can be feeded by it becomes.

• 대한전기학회논문지:전력기술부문A
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• 제51권3호
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• pp.118-126
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• 2002

AVR parameter tuning for voltage control of generators has generally been done with the off-line open-circuit model of the synchronous generator. When the generator is connected on-line and operating with load the AVR operates in an entirely different environment from the open-circuit conditions. This paper describes a new method for AVR parameter tuning for on line conditions using SQP(Sequential Quadratic Programming) meshed with frequency response characteristics of linearized on-line system model. As the proposed method uses the un - line system model the tuned parameter sets show more optimal behavior in the on-line operating conditions. furthermore, as this method considers the performance indices that are needed for stable operation as constraints, AVR parameter sets that are tuned by this method could guarantee the stable performance, too.