• Journal of Electrical Engineering and Technology
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• 제6권4호
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• pp.484-492
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• 2011

Power system analyses, which involve the handling of massive data volumes, necessitate the use of effective visualization methods to facilitate analysis and assist the user in obtaining a clear understanding of the present state of the system. This paper introduces an interface that compensates for the limitations of the visualization modules of dynamic security assessment tools, such as PSS/e and TSAT, for power system variables including generator rotor angle and frequency. The compensation is made possible through the automatic provision of dynamic simulation data in visualized and tabular form for better data intuition, thereby considerably reducing the redundant manual operation and time required for data analysis. The interface also determines whether the generators are stable through a generator instability algorithm that scans simulation data and checks for an increase in swing or divergence. The proposed visualization methods are applied to the dynamic simulation results for contingencies in the Korean Electric Power Corporation system, and have been tested by power system researchers to verify the effectiveness of the data visualization interface.

• Nuclear Engineering and Technology
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• 제51권4호
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• pp.1132-1141
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• 2019

Steel-concrete-steel (SCS) sandwich structures have important advantages over conventional concrete structures, however, bond-slip between the steel plate and concrete may lead to a loss of composite action, resulting in a reduction of stiffness and fatigue life of SCS sandwich structures. Due to the inaccessibility and invisibility of the interface, the interfacial performance monitoring and debonding detection using traditional measurement methods, such as relative displacement between the steel plate and core concrete, have proved challenging. In this work, two methods using piezoelectric transducers are proposed to detect the bond-slip between steel plate and core concrete during the test of the beam. The first one is acoustic emission (AE) method, which can detect the dynamic process of bond-slip. AE signals can be detected when initial micro cracks form and indicate the damage severity, types and locations. The second is electromechanical impedance (EMI) method, which can be used to evaluate the damage due to bond-slip through comparing with the reference data in static state, even if the bond-slip is invisible and suspends. In this work, the experiment is implemented to demonstrate the bond-slip monitoring using above methods. Experimental results and further analysis show the validity and unique advantage of the proposed methods.

• Steel and Composite Structures
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• 제48권2호
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• pp.207-233
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• 2023

Steel-concrete composite box girder bridges are widely used in the construction of highway and railway bridges both domestically and abroad due to their advantages of being light weight and having a large spanning ability and very large torsional rigidity. Composite box girder bridges exhibit the effects of shear lag, restrained torsion, distortion and interface bidirectional slip under various loads during operation. As one of the most commonly used calculation tools in bridge engineering analysis, one-dimensional models offer the advantages of high calculation efficiency and strong stability. Currently, research on the one-dimensional model of composite beams mainly focuses on simulating interface longitudinal slip and the shear lag effect. There are relatively few studies on the one-dimensional model which can consider the effects of restrained torsion, distortion and interface transverse slip. Additionally, there are few studies on vehicle-bridge integrated systems where a one-dimensional model is used as a tool that only considers the calculations of natural frequency, mode and moving load conditions to study the dynamic response of composite beams. Some scholars have established a dynamic analysis model of a coupled composite beam bridge-train system, but where the composite beam is only simulated using a Euler beam or Timoshenko beam. As a result, it is impossible to comprehensively consider multiple complex force effects, such as shear lag, restrained torsion, distortion and interface bidirectional slip of composite beams. In this paper, a 27 DOF vehicle rigid body model is used to simulate train operation. A two-node 26 DOF finite beam element with composed box beams considering the effects of shear lag, restrained torsion, distortion and interface bidirectional slip is proposed. The dynamic analysis model of the coupled composite box girder bridge-train system is constructed based on the wheel-rail contact relationship of vertical close-fitting and lateral linear creeping slip. Furthermore, the accuracy of the dynamic analysis model is verified via the measured dynamic response data of a practical composite box girder bridge. Finally, the dynamic analysis model is applied in order to study the influence of various mechanical effects on the dynamic performance of the vehicle-bridge system.

• 대한기계학회논문집A
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• 제24권11호
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• pp.2823-2827
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• 2000

The dynamic photoelasticity with the aid of Cranz-Shardin type high speed camera system is utilized to record the dynamically propagating behavior of an interface crack. This paper investigates determined the effects of the hole (exited on the path of the crack propagation) on the crack propagation behavior by comparing the experiment isochromatic fringes to the theoretical stress fields.

• 한국지반환경공학회 논문집
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• 제19권12호
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• pp.33-39
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• 2018

본 연구에서는 토목섬유-점토의 접촉면 압밀 전단거동 평가를 위하여 상재하중 및 해수와 담수를 이용해 토목섬유-점토의 경계면에 대한 중요 특성인자를 규명하였다. 또한 폐기물 매립으로 바다에 매립공간을 확보하고 폐기물 처리 및 향후 토지이용 등 새롭게 필요 공간으로 변모가 가능하다. 토목섬유-점토의 접촉면에 거동특성을 분석한 결과 표준 압밀시험기를 이용하여 분석한 경우 해수보다 담수에서 압밀응력이 크게 증가하는 경향을 보였고, 동적 접촉면 전단 시험기를 이용하여 분석한 경우 해수와 담수 두 개의 조건에서 모두 동일하게 하부모듈에 가까운 와이어게이지일수록 변위값이 증가하고, 담수보다 해수의 조건에서 전단파괴가 급격히 일어나는 경향을 볼 수 있다. 따라서 토목섬유-점토의 접촉면에 작용하는 해수와 담수, 차수시설 설치여부(토목섬유)는 차수 시설 동적설계인자에 반드시 필요한 중요 변수로써 고려하여야 한다.

• Geomechanics and Engineering
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• 제29권3호
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• pp.269-279
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• 2022

In this research, a series of dynamic numerical analysis were carried out for deep underground building structures under the various earthquake conditions. Dynamic numerical analysis model was developed based on the PLAXIS2D and calibrated with centrifuge test data from Kim et al. (2016). The hardening soil model with small strain stiffness (HSSMALL) was adopted for soil constitutive model, and interface elements was employed at the interface between plate and soil elements to simulate dynamic interaction effect. In addition, parametric study was performed for fixed condition and embedded depth. Finally, the dynamic behavior of underground building structure was thoroughly analyzed and evaluated.

• 한국농공학회논문집
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• 제50권4호
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• pp.67-75
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• 2008

In construction facilities such as bridges, the fluid boundary layer(or water film) is formed at the structure-soil interface by the inflow into the system due to rainfall or/and rising ground-water. As a result, the structure-soil interaction(SSI) state changes into the structure-fluid-soil interaction(SFSI) state. In general, construction facilities may be endangered by the inflow of water into the soil foundation. Thus, it is important to predict the dynamic SFSI responses accurately so that the facilities may be properly designed against such dangers. It is desired to have the robust tools of attaining such a purpose. However, there has not been any report of a method for the SFSI analyses. The objective of this study is to propose an efficient method of finite element modelling using the new interface element named hybrid interface element capable of giving reasonable predictions of the dynamic SFSI response. This element enables the simulation of the limited normal tensile resistance and the tangential hydro-plane behaviour, which has not been preceded in the previous studies. The hybrid interface element was tested numerically for its validity and employed in the analysis of SFSI responses of the continuous bridge subjected to seismic load under rainfall or/and rising ground-water condition. It showed that dynamic responses of the continuous bridge resting on direct foundation may be amplified under rainfall condition and consequently lead to significant variation of stresses.

• 한국지진공학회논문집
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• 제27권4호
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• pp.163-170
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• 2023

In the fluid-structure interaction analysis, the finite element formulation is performed for the wave equation for dynamic fluid pressure, and the dynamic pressure is defined as a degree of freedom at the fluid nodes. Therefore, to connect the fluid to the structure, it is necessary to connect the degree of freedom of fluid dynamic pressure and the degree of freedom of structure displacement through an interface element derived from the relationship between dynamic pressure and displacement. The previously proposed fluid-structure interface elements use conformal finite element meshes in which the fluid and structure match. However, it is challenging to construct conformal meshes when complex models, such as water purification plants and wastewater treatment facilities, are models. Therefore, to increase modeling convenience, a method is required to model the fluid and structure domains by independent finite element meshes and then connect them. In this study, two fluid-structure interface elements, one based on constraints and the other based on the integration of nonsmooth functions, are proposed in nonconformal finite element meshes for structures and fluids, and their accuracy is verified.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.882-885
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• 2003

In this paper, we describe a haptic jacket and wheel as a haptic interface to enhance VR game realism. Building upon the VR game system using this devices, our haptic interface technique allows the user to intuitive interact on game contents, and then to sense the game event properties such as walking, attacking, driving and fire in a natural way. In addition, we extended the initial haptic model to support haptic decoration and dynamic interactions due to the added game event in a real time display. An application example presented here is a VR Dino-Attack game. This game supports interactions among dynamic and our intuitive haptic interface. Modeling physic interactions involves precise collision detection, real-time force computation, and high control-loop bandwidth.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2010년 춘계학술대회논문집
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• pp.548-550
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• 2010

The droplet motion on a flat substrate with contact angle hysteresis is studied by solving the equations governing the conservation of mass and momentum. The liquid- gas interface is determined by an level-set method which is based on a sharp-interface representation for accurately imposing the matching or coupling conditions at the interface. The method is modified to treat the dynamic contact angle at the liquid-gas-solid interface. The computations are performed to investigate a droplet impact and merging pattern on a flat substrate to find a optimal condition in a micro-line patterning process. The effects of dynamic contact angles on droplet motion are quantified.