• Structural Monitoring and Maintenance
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• 제4권4호
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• pp.365-379
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• 2017

This paper presents a comparison of the black-box and the physics based derived gray-box models for subspace identification for structures subjected to support-excitation. The study compares the damage detection capabilities of both these methods for linear time invariant (LTI) systems as well as linear time-varying (LTV) systems by extending the gray-box model for time-varying systems using short-time windows. The numerically simulated IASC-ASCE Phase-I benchmark building has been used to compare the two methods for different damage scenarios. The efficacy of the two methods for the identification of stiffness parameters has been studied in the presence of different levels of sensor noise to simulate on-field conditions. The proposed extension of the gray-box model for LTV systems has been shown to outperform the black-box model in capturing the variation in stiffness parameters for the benchmark building.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 춘계학술대회
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• pp.1041-1046
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• 2004

A proportional pressure control valve has a nonmagnetic ring which is inserted in between a coil and plunger and it can get attraction force in proportion to input current by an influence of control cone. Therefore, a proportional pressure control valve is applied to a servo system as substitution of servo valve and an on-off solenoid valve widely because control of a high level is possible and pollution level is low. The purpose of this study is to develop domestic model of a proportional pressure control valve, and a test model was designed and manufactured through valve system analysis and finite element analysis. And comparison between results of theoretical analysis and static / dynamic characteristics test were carried out on a manufactured test model, and it was confirmed that it has excellent performance in comparison with other foreign products.

• 제어로봇시스템학회논문지
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• 제13권6호
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• pp.525-530
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• 2007

In this paper, a performance comparison between traditional TPN (true proportional navigation) guidance law and PPN(pure proportional navigation) guidance law is made, based on a short range surface-to-air missile simulation program. This simulation program has a nonlinear aerodynamic missile model, a roll stabilized autopilot, a nonlinear radar model, and a target model, According to the simulation results, the PPN guidance law has better performances than TPN guidance law under the condition of evasive target.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 추계 학술발표회 논문집
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• pp.213-216
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• 2006

The designer has difficulty due to inadequacy of provisions in the domestic design code and lack of understanding for behavior of D-region. The reinforced concrete pi(${\pi}$)-shaped RC rahmen bridge consists of various failure mechanisms as the crushing or splitting from compression concrete, and shearing failure under the loading plate. However, predicting those failure mechanisms is very difficult. In this study, the pi(${\pi}$)-shaped RC rahmen bridge is analyzed and designed by using strut-tie model. Adequacy for the application of strut-tie model is verified by comparison with the way used in current design practice. As a result that designing the structures should be maked a comparison between strut-tie model and current conventional design method.

• 전기학회논문지
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• 제60권4호
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• pp.694-699
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• 2011

This paper compares the performance of lightning shielding analysis methods using the seven striking distance formulae in substation. For comparison, we evaluate the number of expected strikes and exposed area using WinIGS Software. Seven striking distance formulae are compared using the electrogeometric model analysis and the rolling sphere method. Based on the electrogeometric model analysis, the risk of shielding failure in either the whole substation or parts of it is determined. According to the simulation results, one can justify whether the substation satisfies the criterion of shielding design. In particular, according to the rolling sphere method, the exposed areas in substation determine the location of the additional shielding poles or shield wires. Therefore, the installation of the additional shielding poles and shield wires in substation was accepted by shield design at the phase conductors exposed in the larger area.

• Journal of Advanced Marine Engineering and Technology
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• 제26권6호
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• pp.670-678
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• 2002

Fluid flow in a rectangular duct with $90^{\circ}$ mitered elbow is measured by 5W laser doppler velocity meter. The fluid flow is also computed by commercial software of STAR-CD for comparison between measured and computed velocity profiles in the duct. Reynolds numbers for the comparison are 1,608 and 11,751 based on mean velocity and hydraulic diameter of the duct. First, the fluid flow of Reynolds number equal to 1,608 is predicted by assumptions of both laminar and turbulent models. But, even though the Reynolds number is less than 2,300~3,000, the computation by turbulent model is closed to the experimental data than that by laminar model. Second, the computation for Reynolds number of 11,751 by turbulent model also predicted the experimental data satisfactorily.

• 한국화재소방학회:학술대회논문집
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• 한국화재소방학회 1997년도 International Symposium on Fire Science and Technology
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• pp.154-161
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• 1997

Several studies have developed upward flame spread models which use somewhat different features. However, the models have not considered the transient effects of the igniter and the burning rate. Thus, the objective of this study is to examine a generalized upward flame spread model which includes these effects. We shall compare the results with results from simpler models used in the past in order to examine the importance of the simplifying assumptions. We compare these results using PMMA, and we also include experimental results for comparison. The results of the comparison indicate that flame velocity depends on the thermal properties of a material, the specific model for flame length and transient burning rate, as well as other variables including the heat flux by igniter and flame itself. The results from the generalized upward flame spread model can provide a prediction of flame velocity, flame and pyrolysis height, burnout time and position, and rate of energy output as a function of time.

• Journal of applied mathematics & informatics
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• 제41권5호
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• pp.947-961
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• 2023

This paper summarizes some research findings that show how the differential transform method (DTM) is used to resolve the Holling-Tanner model. To confirm the application, effectiveness, and correctness of the approach, a comparison between the differential transform method (DTM) and the Adomian decomposition method (ADM) is carried out, and an accurate solution representation in truncated series is discovered. The approximate solution obtain using both techniques and comparison demonstrates same outcome which remains a preferred numerical method for resolving a system of nonlinear differential equations.

• 소성∙가공
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• 제33권2호
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• pp.87-95
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• 2024

The current study aims to prove that high-speed forming has better formability than conventional low-speed forming. Experimentally, the quasi-static forming limit diagram was obtained by Nakajima test, and the dynamic forming limit diagram was measured by electrohydraulic forming. For the experiments, the LS-DYNA was used to create the optimal specimen for electrohydraulic forming. The strain measurement was performed using the ARGUS, and comparison of the forming limit diagrams confirmed that EHF showed better formability than quasi-static forming. Theoretically, the Marciniak-Kuczynski model was used to calculate the theoretical forming limit. Swift hardening function and Cowper Symonds model were applied to predict the forming limits in quasi-static and dynamic status numerically.

• 대한기계학회논문집A
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• 제38권9호
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• pp.933-941
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• 2014

본 논문에서는 대표적 투영기반 모델차수축소법인 크리로프 부공간 모델차수축소법(KSM)과 모드중첩법(MTM)을 고려하여 주파수응답해석에 대한 수치적 정확도와 효율성을 비교하였다. 두 모델차수축소법의 수치 정확도 비교를 위하여 주파수응답해석 결과, 축소차수 및 관심주파수에 따른 상대오차를 고려하였으며 이후에 오차수렴지표를 통한 자동적인 축소차수의 결정이 가능 여부를 확인하였다. 효율성 비교를 위해서는 각 축소모델의 주파수응답 해석시간 및 축소차수에 따른 변환행렬 생성시간을 비교하였다. 자동차 현가장치에 대한 유한요소모델을 적용예제로 선정하여 수치 비교를 수행하였다.