• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.26 no.5
• /
• pp.546-551
• /
• 2016

The objective of this study is to investigate the response delays between piezo-stack actuator and the displacement magnifier of jetting dispenser and to reduce its falling time in terms of displacement optimization. The dispenser is driven by the dual piezo-stack actuators with a hinge lever mechanism to precisely control flow rate of the working fluid (3000 cP). It is commonly found that piezo actuator-driven jetting dispensers involving viscous working fluids have displacement optimization problem for ideal performance. The response delay of the system is caused by the phenomenon that the displacement magnifier cannot exactly follow the motion of the piezo actuators. The response delay may lower the performance of the system due to the inaccurate discharge of working fluid or even damages to the system itself due to inharmonious motion of piezo actuators with lever system. To reduce its response delay, a new displacement profile obtained from displacement optimization is suggested; its performance is tested through finite element analysis; and experiments are carried out to verify the performance of the obtained displacement profile.

• Journal of the Architectural Institute of Korea Structure & Construction
• /
• v.36 no.4
• /
• pp.135-142
• /
• 2020

The new method for evaluating the displacement tolerance of sky-bridges with pin-roller type supports was proposed considering both return period of phase difference between connected buildings and geometrical characteristics of skybridge. Because displacement tolerance is relative value, which is most affected by the phase difference of the connected buildings, the dynamic response of these building with time history analysis should be evaluated. However, the initial phase could not be specified, so the result of displacement tolerance would be varied with respect to initial value. Thus, the tolerance can be reasonably evaluated SRSS calculation with design displacements based on statistical approach and of each building. In addition, the geometrical characteristics of sky-bridge should be considered because the transverse displacement of sky-bridge span causes the shear deformation of the bridge and longitudinal displacement tolerance cannot release the shear deformation. Therefore, the some pin-end support in sky-bridge should have longitudinal displacement tolerance to accommodate the shear deformation. By resolving this shear deformation, it is possible not only to accommodate transverse displacement, but also to avoid the complicated joint details such as both pot bearing and guided supports with shear key.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
• /
• 1997.04a
• /
• pp.113-118
• /
• 1997

This paper presents the dimensional synthesis and kinematic analysis of the RSCS-SSP motion generating spatial mechanism using the displacement matrix method. This type of spatial mechanisms is used for the Mcpherson suspension in small automobiles. It is modeled for the wheel bump/rebound and steering motion. First, the suspension is modeled as a multiloop spatial rigid body guidance mechanism for the two major motions. Then the design equations for SSP, RS, and SC strut links are applied to synthesize an RSCS-SSP for up to three prescribed positions for the steering motiom from the suspension design specification. Thus a RSCS-SSP mechanism which is synthesized is also analyzed for the displacement during the steering motion.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.21 no.11
• /
• pp.1844-1851
• /
• 1997

Displacement fields and interface stresses are obtained by modifying the potential energy functional with a penalty function which enforces the continuity of stresses at the interface of two-materials. Based on the displacement field and the interface stresses, a new methodology to generate a continuous stress field over the entire domain including the interface of the dissimilar materials has been proposed by combining the L$^{2}$ projection method of stress-smoothing and the Loubignac's iterative method of improving the displacement field. Stress analysis was carried out on two examples which are made of highly dissimilar materials. As a result of the analysis, it is found that the proposed method provides improved continuity of the stress field over the entire domain as well as predicting accurate nodal stresses at the interface. In contrast, the conventional displacement-based finite element method provides significant stress discontinuties at the interfaces. In addition, it was found that the total strain energy evaluated from the improved continuous stress field converge to the exact value as increasing the number of iterations in the proposed method.

• Journal of the Korean Society of Industry Convergence
• /
• v.23 no.2_2
• /
• pp.361-374
• /
• 2020

Recently, small and medium-sized rahmen-type bridges have been developed as a technology that ensures the stability of structural behavior and the safety of use at the same time by using efficient and economical materials that make up the convergence section of reinforced bar, structural steel and concrete. This study is about a rahmen-type structure applied with the installation and dismantling of the strut. It improves the serviceability of the structure by forming multi-points and efficiently applies the convergence section of structural steel and concrete materials to the structural system changes to induce the displacement improvement effect additionally. By constructing mock-up models for the beam-column joint, the displacement was calculated and compared, and this was compared and analyzed by numerical analysis. The final displacement showed an improvement effect of 13.46% to 36.28% based on the vertical displacement of the existing structure without struts through the experiment of the mock-up models. As a result of analysis by numerical analysis method, the displacement improvement effect of 42.89% could be derived.

• Wind and Structures
• /
• v.9 no.3
• /
• pp.217-230
• /
• 2006

This paper describes a procedure to develop fragility curves for woodframe structures subjected to lateral wind loads. The fragilities are cast in terms of horizontal displacement criteria (maximum drift at the top of the shearwalls). The procedure is illustrated through the development of fragility curves for one and two-story residential woodframe buildings in high wind regions. The structures were analyzed using a monotonic pushover analysis to develop the relationship between displacement and base shear. The base shear values were then transformed to equivalent nominal wind speeds using information on the geometry of the baseline buildings and the wind load equations (and associated parameters) in ASCE 7-02. Displacement vs. equivalent nominal wind speed curves were used to determine the critical wind direction, and Monte Carlo simulation was used along with wind load parameter statistics provided by Ellingwood and Tekie (1999) to construct displacement vs. wind speed curves. Wind speeds corresponding to a presumed limit displacement were used to construct fragility curves. Since the fragilities were fit well using a lognormal CDF and had similar logarithmic standard deviations (${\xi}$), a quick analysis to develop approximate fragilities is possible, and this also is illustrated. Finally, a compound fragility curve, defined as a weighted combination of individual fragilities, is developed.

• Geomechanics and Engineering
• /
• v.15 no.4
• /
• pp.947-955
• /
• 2018

In this study, we propose a three-dimensional simplified slope stability analysis using a hybrid-type penalty method (HPM). In this method, a solid element obtained by the HPM is applied to a column that divides the slope into a lattice. Therefore, it can obtain a safety factor in the same way as simplified methods on the slip surface. Furthermore, it can obtain results (displacement and strain) that cannot be obtained by conventional limit equilibrium methods such as the Hovland method. The continuity condition of displacement between adjacent columns and between elements for each depth is considered to incorporate a penalty function and the relative displacement. For a slip surface between the bottom surface and the boundary condition to express the slip of slope, we introduce a penalty function based on the Mohr-Coulomb failure criterion. To compute the state of the slip surface, an r-min method is used in the load incremental method. Using the result of the simple three-dimensional slope stability analysis, we obtain a safety factor that is the same as the conventional method. Furthermore, the movement of the slope was calculated quantitatively and qualitatively because the displacement and strain of each element are obtained.

• Tunnel and Underground Space
• /
• v.18 no.5
• /
• pp.355-365
• /
• 2008

Displacement caused by tunneling is difficult to predict since it is affected by many factors such as ground condition, excavation method and supplementary method of reinforcement. In this study, horizontal inclinometer was employed to monitor ground settlements above a tunnel face before and after the excavation. Monitoring results were analyzed to predict the preceding displacement and settlement of the surface structures. The result of the analysis can be used to establish a proper counter measure which keeps the serviceability of the surface structures. Based on the analysis of the monitoring result, ground properties of the site were deduced and the influence of the tunnel excavation on the settlement of the foundation above the tunnel is analyzed.

• Structural Engineering and Mechanics
• /
• v.71 no.5
• /
• pp.545-552
• /
• 2019

The analysis and design of complex structures like sandwich-panel elements are difficult; the use of finite element method for the analysis is complicated and time consuming when non-linear effects are considered. On the other hand, artificial neural network (ANN) models can capture the non-linear effects and its application requires lesser computational demand. Two ANN models were trained, tested and validated to compute the force for a given displacement of a sandwich-type roof element; 2555 force and element deformation pairs were used for training the ANN models. For the models trained without considering the damping effect, there were two values in the input layer: maximum displacement and current displacement, and for the model considering damping, displacement from the previous step was used as an additional input. Totally, 400 ANN models were trained. Results show that there is a good agreement between the experimental and simulated data, and the models showed a good performance with a mean square error value of 4548.85. Both the ANN models could simulate the inelastic behaviour, loss of rigidity, and evolution of permanent displacements. The models could also interpolate and extrapolate, which enables them to be used as an analysis and design tool for such complex elements.

• Journal of Korean Association for Spatial Structures
• /
• v.24 no.1
• /
• pp.89-98
• /
• 2024

In this study, we investigated the dynamic characteristics of three irregular building models to analyze the effectiveness of displacement response control with Tuned Mass Damper (TMD) installation in twisted irregular buildings. The three irregular models were developed with a fixed angle of twist per story at one degree, subjected to three historical seismic loads and resonant harmonic loads. By designing TMDs with linear and dashpot attributes, we varied the total mass ratio of the installed TMDs from 0.00625% to 1.0%, encompassing a total of 10 values. Two TMDs were installed at the center of the top story of the analysis model in both X and Y directions to evaluate displacement response control performance based on TMD installation. Our findings suggest that the top displacement response control performance was most effective when a 1.0% TMD was installed at the top layer of the analysis model.