• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2009년도 춘계학술대회 논문집
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• pp.181-182
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• 2009

• JSTS:Journal of Semiconductor Technology and Science
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• 제14권6호
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• pp.728-732
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• 2014

Macro-model of magnetic tunnel junction (MTJ) for spin transfer torque magnetic random access memory (STT-MRAM) has been developed. The macro-model can describe the dynamic behavior such as the state change of MTJ as a function of the pulse width of driving current and voltage. The statistical behavior has been included in the model to represent the variation of the MTJ characteristic due to process variation. The macro-model has been developed in Verilog-A.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2009년도 춘계학술대회 논문집
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• pp.1557-1565
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• 2009

According to the GM/RT2141, to assess the safety of vehicle, the validated the vehicle dynamic model should be applied. The validation of the vehicle model is against the static test, some kind of vehicle type test results have been used to determine the suspension characteristics and the vehicle dynamic characteristics. To validate the vehicle model and the test results, first the test results has been analysed as to specified the suspension characteristics and than the parameters to related with the test result has to be adjusted to show the same results of the test. In this process the parameters of vehicle model have been determined to show the coherence of the two results of the simulation and the test by trial & error. In this report, the optimization tool has been introduced in this model validation process and shows the efficient and well validated model.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1997년도 춘계학술발표회논문집(2)
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• pp.407-412
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• 1997

The predictive results between a dynamic food-chain model (DYNACON) and an equilibrium model (NRC model) were compared to show the physical validity of DYNACON. Although the mathematical formulations and transport processes of radionuclides in the environment are different between two models, the comparative study shows good agreement for deposition events that occur during the growing season of plants.

• 정보처리학회논문지C
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• 제15C권6호
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• pp.493-506
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• 2008

본 논문은 역할 기반 접근 제어 모델 연구를 통해 u-헬스케어 환경의 요구사항을 충족하는 상황 기반의 동적 접근제어 모델을 제안한다. 동적 보안 도메인 관리를 위해 분산객체그룹 프레임워크를 사용하였고, 동적 접근제어를 위한 상황 정보는 기 구축된 데이터베이스를 사용하였다. 본 논문에서는 러프집합 이론을 근거로 의사결정 테이블에서 지식감축을 통해 의사결정 규칙을 정의하고, 생성된 규칙을 동적 접근제어 모델에 적용하였다. 그리고 분산객체그룹 프레임워크를 기반으로 u-헬스케어 응용을 통해 상황기반 동적 보안 서비스의 수행 결과를 보였다. 이 결과, 동적 접근 제어 모델은 u-헬스케어 환경에서 보안 도메인에 따라 적합한 보안 서비스와 보다 유연한 접근제어를 제공한다.

• 대한기계학회논문집A
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• 제24권12호
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• pp.3080-3087
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• 2000

We obtain the mathematical model of the hard disk drive actuator system the system response data of the finite element analysis or experimental results. The model is base on the Rayleigh-Ritz method to approximate the dynamic response of the actuator system. The basic idea is to use the curve-fit technique to obtain the approximation coefficients. It allows the dynamic analysis of the actuator system without resort to the repetitive finite element modeling work. Even though the dynamic characteristics of the system of the system are affected somewhat by the structural modification and the change of the material properties, we can use the modified size and dynamic properties of the actuator system in the mathematical model to some extent. In this study, we express the mathematical model of the simplified rectangular plate first and then proceed to the actual hard disk drive actuator system.

• Structural Engineering and Mechanics
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• 제6권1호
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• pp.63-76
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• 1998

This paper presents dynamic responses of structures with sliding base which limits the translation of external loads from ground excitation. A discrete element model based on the discontinuous deformation analysis method is proposed to study this sliding boundary problem. The sliding base is simulated using sets of fictitious contact springs along the sliding interface. The set of contact spring is to translate friction force from ground to superstructure. Validity of the proposed model is examined by the closed-form solutions of an idealized mass-spring structural model subjected to harmonic ground excitation. This model is also applied to a problem of a three-story structural model subjected to the ground excitation of 1940 El Centro earthquake. Analyses of both sliding-base and fixed-base conditions are performed as comparisons. This study shows that using this model can simulate the dynamic response of a sliding structure with frictional cut-off quite accurately. Results reveal that lowering the frictional coefficient of the sliding joint will reduce the peak responses. The structure responses in little deformation, but it displaces at the end of excitation.

• 대한기계학회논문집A
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• 제26권2호
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• pp.267-274
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• 2002

Using a flexible rotating beam test bed, experimental verification of a flexible multibody dynamic simulations for a rotating beam model has been carried out. The test bed consists of a flexible arm, harmonic driver reducer, AC servo motor and DSP board with PC. The mechanical ports of the test bed has been designed using 3D CAD program. For the simulation model, mass and moment of inertia of each part of the flexible rotating beam test bed are also obtained from 3D CAD model. In the flexible multibody dynamic simulations, the substructuring model has been established to capture nonlinear effects of the flexible rotating beam. Through the experimental verification, substructuring model provides better results than those from the linear model in the high speed rotation.

• 대한교통학회지
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• 제19권4호
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• pp.97-108
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• 2001

기존의 동적 통행배정모형은 출발시간 선택에 있어서 도착시간제약을 고려하지 못하고 있으며, 이를 고려하더라도 수단분담을 고려하지 못하거나 별도의 문제로 다루고 있다. 따라서 대중교통의 수단분담비가 높고, 도착시간에 대한 제약이 따르는 출근·통학통행이 주류를 이루는 오전첨두시의 교통관리·분석을 위해서는 이들을 동시에 고려하는 동적 통행배정모형이 요구된다. 본 연구에서는 Ran과 Boyce가 구축한 모형에 기반하여 통행수단과 도착시간 제약에 따른 출발시간 선택을 경로선택과 동시에 고려할 수 있는 통합모형을 제시하였다. 모형의 풀이를 위해 Ran과 Boyce가 사용한 시·공간 확장 가로망을 새롭게 설계하여 사용하였으며, 가상 가로망에 적용하여 모형의 적합성을 검증하였다. 사례연구 결과 본 연구에서 제시한 모형이 동적 사용자최적 통행배점상태를 나타내는 것을 확인할 수 있었고, 이를 통해 오전 첨두시의 교통관리·분석을 위해 적용 가능함을 입증하였다.

• Structural Engineering and Mechanics
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• 제59권4호
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• pp.601-619
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• 2016

In this study, developments of an efficient visco-hyperelastic constitutive equation for describing the time dependent material behavior accurately in dynamic and impact loading and finding related materials constants are considered. Based on proposed constitutive model, behaviour of a hollow cylinder elastomer bushing under different dynamic and impact loading conditions is studied. By implementing the developed visco-hyperelastic constitutive equation to LS-DYNA explicit dynamic finite element software a three dimensional model of the bushing is developed and dynamic behaviour of that in axial and torsional dynamic deformation modes are studied. Dynamic response and induced stress under different impact loadings which is rarely studied in previous researches have been also investigated. Effects of hyperelastic and visco-hyperelastic parameters on deformation and induced stresses as well as strain rate are considered.