• Journal of Fashion Business
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• v.19 no.3
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• pp.130-143
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• 2015

By studying 3-D virtual human modeling, motion-capturing and clothing simulation for easier and safer work clothes development, this research aimed (1) to categorize heavy manufacturing work motions; (2) to generate a 3-D virtual male model and establish painting work motions within a 3-D virtual clothing simulation system through computerized body scanning and motion-capturing; and finally (3) to suggest simulated clothing images of painting work clothes developed based on virtual male avatar body measurements by implementing the work motions defined in the 3-D virtual clothing simulation system. For this, a male subject's body was 3-D scanned and also directly measured. The procedures to edit a 3-D virtual model required the total body shape to be 3-D scanned into a digital format, which was revised using 3-D Studio MAX and Maya rendering tools. In addition, heavy industry workers' work motions were observed and recorded by video camera at manufacturing sites and analyzed to categorize the painting work motions. This analysis resulted in 4 categories of motions: standing, bending, kneeling and walking. Besides, each work motion category was divided into more detailed motions according to sub-work posture factors: arm angle, arm direction, elbow bending angle, waist bending angle, waist bending direction and knee bending angle. Finally, the implementation of the painting work motions within the 3-D clothing simulation system presented the virtual painting work clothes images simulated in a dynamic mode.

• Earthquakes and Structures
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• v.23 no.2
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• pp.115-128
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• 2022

One common method to select input ground motions to predict dynamic behavior of structures subjected to seismic excitation requires spectral acceleration (S_a) match target mean response spectrum. However, dispersion of ground motions, which explicitly affects the structural response, is rarely discussed in this method. Generally, selecting ground motions matching target mean and variance has been utilized as an appropriate method to predict reliable seismic response. The goal of this paper is to investigate the impact of target spectra variance of ground motions on structural seismic response. Two sets of ground motions with different target variances (zero variance and minimum variance larger than inherent variance of the target spectrum) are selected as input to two different structures. Structural responses at different heights are compared, in terms of peak, mean and dispersion. Results show that increase of target spectra variance tends to increase peak floor acceleration, peak deformation and dispersions of response of interest remarkably. To short-period structures, dispersion increase ratios of seismic response are close to that of S_a of input ground motions at the first period. To long-period structures, dispersions of floor acceleration and floor response spectra increase more significantly at the bottom, while dispersion increase ratios of IDR and deformation are close to that of S_a of input ground motions at the first period. This study could further provide useful information on selecting appropriate ground motion to predict seismic behavior of different types of structures.

• Structural Engineering and Mechanics
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• v.11 no.6
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• pp.663-672
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• 2001

Numerous failures in welded connections in steel moment-resisting building frames (SMRF) were observed when buildings were inspected after the 1994 Northridge Earthquake. These observations raised concerns about the effectiveness of such frames for resisting strong earthquake ground motions. The behavior of SMRFs during an earthquake must be assessed using nonlinear dynamic analysis, and such assessments must permit the deterioration in connection strength to capture the behavior of the frame. The uncertainties that underlie both structural and dynamic loading also need to be included in the analysis process. This paper describes the analysis of one of approximately 200 SMRFs that suffered damage to its welded beam-to-column connections from the Northridge Earthquake is evaluated. Nonlinear static and dynamic analysis of this SMRF in the time domain is performed using ground motions representing the Northridge Earthquake. Subsequently, a detailed uncertainty analysis is conducted for the building using an ensemble of earthquake ground motions. Probability distributions for deformation-related limit states, described in terms of maximum roof displacement or interstory drift, are constructed. Building fragilities that are useful for condition assessment of damaged building structures and for performance-based design are developed from these distributions.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.8
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• pp.19-26
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• 2003

A steady prediction method of dynamic stability derivatives is presented in the unified framework of the unsteady Euler equations. New approach does not require any modification of the governing equations except addition of non-inertial force terms. The present methods are applied to compute the pitch-damping coefficients using the lunar coning and the lunar helical motions in the Cartesian coordinate frame. The results for the ANSR and the Basic Finner are in good agreement with the PNS data, range data, and the results using the unsteady prediction method. The results show that the steady approach using the unified governing equations in the Cartesian coordinate frame can be successfully applied to predict the pitch-damping coefficients.

• Ocean Systems Engineering
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• v.3 no.3
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• pp.203-217
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• 2013

A PTO (power-take-off) mechanism by using relative heave motions between a floating buoy and its inner mass (magnet or amateur) is suggested. The inner power take-off system is characterized by a mass with linear stiffness and damping. A vertical truncated cylinder is selected as a buoy and a special station-keeping system is proposed to minimize pitch motions while not affecting heave motions. By numerical examples, it is seen that the maximum power can actually be obtained at the optimal spring and damper condition, as predicted by the developed WEC(wave energy converter) theory. Then, based on the developed theory, several design strategies are proposed to further enhance the maximum PTO, which includes the intentional mismatching among heave natural frequency of the buoy, natural frequency of the inner dynamic system, and peak frequency of input wave spectrum. By using the intentional mismatching strategy, the generated power is actually increased and the required damping value is significantly reduced, which is a big advantage in designing the proposed WEC with practical inner LEG (linear electric generator) system.

• Journal of the Society of Naval Architects of Korea
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• v.47 no.2
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• pp.248-257
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• 2010

In this study, a discrete event and dynamic-based discrete time combined simulation modeling architecture, which can be used to calculate equations of motions among discrete events, is developed. This is composed of a command model, which is in charge of discrete event simulation, a numerical integration model, which finds motions by numerically integrating equations of motions, and an external force and control force model, which calculates the force and transmits it to the equations. Using this architecture, we can develop dynamic-based simulation by simply connecting and combining models, and handle simultaneously discrete event and discrete time simulation. To verify the efficiency of the architecture, it is applied to the submarine diving and surfacing simulation.

• International Journal of Automotive Technology
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• v.7 no.7
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• pp.777-784
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• 2006

The lateral dynamic behaviours of a track inspection vehicle with laterally guided system are studied for the safety and comfort. A 10-DOF dynamic model is proposed counting for lateral and yaw motions. The equations for motions of the vehicle running on curved tracks at a constant speed are presented. It is shown by simulation that lateral guiding forces applied to the guiding wheels on the inner side of the track increase in a larger scale in comparison with those on the outer side when the vehicle passes through curved tracks with cant, and the front guiding spring forces is larger than the rears. Lateral vibrations due to yaw motions of the vehicle take place when the vehicle runs through curved tracks. Finally, effect of the lateral guidance on the vehicle dynamics is also examined and advantages of such a guiding system are discussed in some details. An optimal guided control is applied to restrain the lateral and yaw motions. The comparisons between the active and passive guidance explain the effect of the active control approaches.

• Earthquakes and Structures
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• v.13 no.2
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• pp.211-220
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• 2017

Observations from past strong earthquakes revealed that near-fault ground motions could lead to the failure, or even collapse of electricity transmission towers which are vital components of an overhead electric power delivery system. For assessing the performance and robustness, a high-fidelity three-dimension finite element model of a long span transmission tower-line system is established with the consideration of geometric nonlinearity and material nonlinearity. In the numerical model, the Tian-Ma-Qu material model is utilized to capture the nonlinear behaviours of structural members, and the cumulative damage D is defined as an index to identify the failure of members. Consequently, incremental dynamic analyses (IDAs) are conducted to study the collapse fragility, damage positions, collapse margin ratio (CMR) and dynamic robustness of the transmission towers by using twenty near-fault ground motions selected from PEER. Based on the bending and shear deformation of structures, the collapse mechanism of electricity transmission towers subjected to Chi-Chi earthquake is investigated. This research can serve as a reference for the performance of large span transmission tower line system subjected to near-fault ground motions.

• Structural Engineering and Mechanics
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• v.78 no.3
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• pp.333-350
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• 2021

Motivated by the demand of seismic protection of museum collections and development of performance-based seismic design guidelines, this paper investigates the seismic fragility of sliding artifacts based on incremental dynamic analysis and three-dimensional finite element model of the artifact-showcase-museum system considering nonlinear behavior of the structure and contact interfaces. Different intensity measures (IMs) for seismic fragility assessment of sliding artifacts are compared. The fragility curves of the sliding artifacts in both freestanding and restrained showcases placed on different floors of a four-story reinforced concrete frame structure are developed. The seismic sliding fragility of the artifacts within a real-world museum subjected to bi-directional horizontal ground motions is also assessed using the proposed IM and engineering demand parameter. Results show that the peak floor acceleration including only values initiating sliding is an efficient IM. Moreover, the sliding fragility estimate for the artifact in the restrained showcase increases as the floor level goes higher, while it may not be true in the freestanding showcase. Furthermore, the artifact is more prone to sliding failure in the restrained showcase than the freestanding showcase. In addition, the artifact has slightly worse sliding performance subjected to bi-directional motions than major-component motions.

• Geotechnical Engineering
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• v.6 no.2
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• pp.5-20
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• 1990

In the seismic analysis of structures, where the dynamic soil-structure interaction (DSSI) is considred, earthquake input motions as well as dynamic soil properties are random in nature. To take into account the random nature of both the input motions and the dynamic soil properties systematically, a probabilistic analysis of the DSSI subjected to seismic loading is proposed in this paper, The complex response method formulized by the elastic half space theory, the random vibration theory, and the Rosenblueth's two-point estimate method are combined for the proposed probabilistic analysis. The conclusions drawn from this study are as follows ' 1) The uncertainty bands of the earthquake input motions proposed by Kanai-Tajimi as well as those of the dynamic properties are large the coefecients of variation of those parameters tinge from 0.4 to 0.6. 2) The uncertainties of the dynamic soil properties are more sensitive to the structural responses than those of the input motion parameters. 3) The effect of correlations between the input motion parameters and the dynamic soil properties is negligible.