• Journal of Mechanical Science and Technology
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• 제19권spc1호
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• pp.255-264
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• 2005

In this paper, a practical bushing model is proposed to improve the accuracy of the vehicle dynamic analysis. The results of the rubber bushing are used to develop an empirical bushing model with an artificial neural network. A back propagation algorithm is used to obtain the weighting factor of the neural network. Since the output for a dynamic system depends on the histories of inputs and outputs, Narendra algorithm of 'NARMAX' form is employed to consider these effects. A numerical example is carried out to verify the developed bushing model. Then, a full car dynamic model with artificial neural network bushings is simulated to show the feasibility of the proposed bushing model.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 춘계학술대회논문집
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• pp.1023-1026
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• 2007

Optimal damping layout of the constrained viscoelastic damping layer on beam is identified with temperatures by using a gradient-based numerical search algorithm. An optimal design problem is defined in order to determine the constrained damping layer configuration. A finite element formulation is introduced to model the constrained damping layer beam. The four-parameter fractional derivative model and the Arrhenius shift factor are used to describe dynamic characteristics of viscoelastic material with respect to frequency and temperature. Frequency-dependent complex-valued eigenvalue problems are solved by using a simple resubstitution algorithm in order to obtain the loss factor of each mode and responses of the structure. The results of the numerical example show that the proposed method can reduce frequency responses of beam at peaks only by reconfiguring the layout of constrained damping layer within a limited weight constraint.

• 한국자동차공학회논문집
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• 제10권1호
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• pp.244-254
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• 2002

To enhance the acceleration performance and fuel consumption rate of a vehicle, the torque converter is modified or newly-developed with reliable analysis model. Up to recently, the one dimensional performance model has been used for the analysis and design of torque converter. The model is described with constant parameters based on the concept of mean flow path. When it is used in practice, some experiential correction factors are needed to minimize tole estimated error. These factors have poor physical meaning and cannot be applied confidently to the other specification of torque converter. In this study, the detail dynamic model of torque converter is presented to establish the physical meaning of correction factors. To verify the validity of model, performance test was carried out with various input speed and oil temperature. The effect of oil temperature on the performance is analysed, and it is applied to the dynamic model. And, to obtain the internal flow pattern of torque converter, CFD(Computational Fluid Dyanmics) analysis is carried out on three-dimensional turbulent flow. Correction factors are determined from the internal flow pattern, and their variation is presented with the speed ratio of torque converter. Finally, the sensitivity of correction factors to the speed ratio is studied for the case of changing capacity factor with maintaining torque ratio.

• 한국항행학회논문지
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• 제16권2호
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• pp.367-374
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• 2012

박판 폐단면을 갖는 프레임과 같은 보가 warping 조건하에서 동적 거동 특성이 어떠한가를 시뮬레이션과 시험을 통하여 제시하였다. 비틀림 모멘트를 받는 보는 단면은 비틀림 뿐만 아니라 warping에 의해서 변형을 일으키게 된다. 어떤 박판 단면을 갖는 보에서는 warping이 매우 커서 축방향과 전단방향 응력을 발생하고 보의 비틀림에 저항이 크게 된다. 이 논문에서는 유한요소에서 warping restraint factor가 보의 변형 거동과 동적 모드에 미치는 영향을 살펴본다. 유한 보 요소와 박판 요소 모델을 사용하여 정적변형과 고유주파수 및 모드해석을 시뮬레이션하며 이 결과를 시험 결과와 비교한다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2014년도 추계학술대회 논문집
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• pp.1004-1006
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• 2014

This study was conducted to improve the understanding of factors affecting an automobile seat cushion in dynamic conditions. When there are two dummies on the seat to measure each places respectively at once, the shape of the transfer function changes because the dummies affect each other as if they are linked with some kind of a spring when under excitation. A simple two-degree-of-freedom linear model is used to define a translational stiffness of dynamic coupling phenomenon. The cushion deflection model was created to find the relation between dynamic coupling and distance. Experimental set-up was made to compare with the two-degree-of-freedom linear model. The dynamic coupling factor could be utilized to improve the dynamic comfort of automobile seats.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2001년도 가을 학술발표회 논문집
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• pp.485-492
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• 2001

The dynamic analysis model is developed with the high-speed train (KTX) and a 2-span continuous prestressed concrete box girder bridge with a double track. The analytical results are compared with the dynamic field test results and found to be valid to yield quite accurate dynamic responses. The various trainset models with different number of cars are developed and compared with the results of the regular 20-car trainset model. It is concluded that the reduced trainset models, such as 7-car and 10-car models, cannot exactly produce the dynamic responses of bridges, especially when the train speed is high. Under the coincidence condition of two trains traveling with resonance velocity in the opposite directions, it is found that the impact factor under two-way coincidence is three times larger than that under one-way traffic. Consequently, for the bridge with a double-track it is necessary to check not only the dynamic responses of the bridge with one-way traffic but those with two-way coincidence.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1997년도 춘계학술발표회논문집(1)
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• pp.437-443
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• 1997

DYLAM and its related applications are reviewed in detail and found to have many favorable characteristics. Concerning human factor analysis, the study demonstrates that DYLAM methodology represents an appropriate tool to study man-machine behavior provided that DYLAM is used to model machine behavior and an appropriate operator interface human factor model is included. A hybrid model which is a synthesis of the DYLAM model, a system thermodynamic simulation model and a neural network predicative model, is implemented and used to analyze dynamically the CANDU pressurizer system.

• 한국에너지공학회:학술대회논문집
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• 한국에너지공학회 1995년도 추계학술발표회 초록집
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• pp.75-81
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• 1995

DYLAM and its related applications are reviewed in detail and found to have many favourable characteristics. Concerning human factor analysis, the study demonstrates that DYLAM methodology represents an appropriate tool to study man-machine behaviour provided that DYLAM is used to model machine behaviour and an appropriate operator interface human factor model is included. A hybrid model which is a synthesis of the DYLAM model, a system thermodynamic simulation model and a neural network predicative model, is implemented and used to analyse dynamically the CANDU pressurizer system.

• Structural Engineering and Mechanics
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• 제6권4호
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• pp.467-471
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• 1998

A mathematical model is developed to predict the fatigue notch factor of butt welds subject to number of parameters such as weld geometry, residual stresses under dynamic combined loading conditions (tensile and bending). Linear elastic fracture mechanics, finite element analysis, dimensional analysis and superposition approaches are used for the modelling. The predicted results are in good agreement with the available experimental data. As a result, scatters of the fatigue data can be significantly reduced by plotting S-N curve as ($S{\cdot}K_f$) vs. N.

• KDI Journal of Economic Policy
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• 제12권4호
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• pp.3-20
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• 1990

다부문모형(多部門模型)은 산업련관자료(産業聯關資料)를 비롯한 산업정보자료(産業情報資料)를 이용하여 장기의 구조변화를 분석 전망하고 총생산성(總生産性)과 요소가격(要素價格)의 변동에 의한 산업경쟁력(産業競爭力)의 추이를 분석하여 중기의 성장전망(成長展望)을 시산(試算)하는 연간(年間) 계량모형(計量模型)으로 25개 산업부문(産業部門)의 1,300여개(餘個)의 구조식(構造式) 정의식(定義式)으로 구성된다. 국내가격과 국제가격(國際價格)의 차이가 산업 무역구조에 영향을 미치고 국내생산과 요소가격이 산업별 요소수요(要素需要)를 결정하며 요소수요와 요소가격에 의하여 소득(所得)이 결정되고 소득과 가격이 산업별 소비지출(消費支出)을 결정한다 ; 산업별 총생산성과 상대가격(相對價格)이 투입산출계수(投入産出係數)에 영향을 미치고 투입산출계수와 상대가격이 산업별 생산비용(生産費用)을 결정하며 생산비용과 경쟁수입가격(競爭輸入價格)을 고려하여 국내가격이 결정된다 ; 생산성증가(生産性增加)와 임금상승(賃金上昇)의 산업간(産業間) 차이가 상대가격(相對價格)을 변화시키고 이로 인하여 산업(産業) 무역(貿易) 고용구조(雇傭構造)가 선진국(先進國)과 동질화(同質化)되는 지식(知識) 기술집약화(技術集約化) 과정이 전개된다.