• Structural Engineering and Mechanics
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• v.38 no.5
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• pp.651-674
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• 2011

This paper presents a novel method for predicting the failure probability of structural or mechanical systems subjected to random loads and material properties involving multiple design points. The method involves Multicut High Dimensional Model Representation (Multicut-HDMR) technique in conjunction with moving least squares to approximate the original implicit limit state/performance function with an explicit function. Depending on the order chosen sometimes truncated Cut-HDMR expansion is unable to approximate the original implicit limit state/performance function when multiple design points exist on the limit state/performance function or when the problem domain is large. Multicut-HDMR addresses this problem by using multiple reference points to improve accuracy of the approximate limit state/performance function. Numerical examples show the accuracy and efficiency of the proposed approach in estimating the failure probability.

• Korean Journal of Computational Design and Engineering
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• v.17 no.5
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• pp.375-386
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• 2012

Most engineering design problems require analyses or simulations to evaluate objective functions. However, a single simulation can take many hours or even days to finish for many real world problems. As a result, design optimization becomes impossible since they require hundreds or thousands of simulation evaluations. The surrogate-based optimization (SBO) strategy became a remedy for such computationally expensive analyses and simulations. A surrogate-based optimization strategy has been developed in this study in order to improve global optimization performance. The strategy is a heuristic algorithm and it exploits not only multiple surrogates, but also multiple optimizers. Multiple optimizations of multiple surrogate models yield multiple candidate design points of optima. During the sequential sampling process, the algorithm ranks candidate design points, selects the points as many as specified, and builds the improved surrogate model. Various mathematical functions with different numbers of design variables are chosen to compare the proposed method with the other most recent algorithm, MSEGO. The proposed method shows superior performance to the other method.

• Korean Journal of Computational Design and Engineering
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• v.5 no.3
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• pp.285-292
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• 2000

A new method for the 3D automatic registration of the multiple range images has been developed for the 3D scanners(non-contact coordinates measurement systems). In the existing methods, the user usually has to input more than 3 pairs of corresponding points for the iterative registration process. The major difficulty of the existing systems lies in that the input corresponding points must be selected very carefully because the optimal searching process and the registration results mostly depend upon the accuracy of the selected points. In the proposed method, this kind of difficulty is greatly mitigated even though it needs only 2 pairs of the corresponding input points. Several registration examples on the 3D measured data have been presented and discussed with the introduction to the proposed algorithm.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.55 no.12
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• pp.514-521
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• 2006

The existing ULTC operation control strategy based on the measured data deteriorates the voltage compensation capability making the efficient corresponding to the load variation difficult by following the fixed load center point voltage. Accordingly, this paper proposes a new on-line fuzzy ULTC controller based on the designed multiple load center points which can improve the voltage compensation capability of ULTC and minimize voltage deviation by moving in real-time the load center point according to the load variation to an adequate position among the multiple load center points designed using the clustering technique. The Max-Min distance technique is adopted as the clustering technique for the decision of multiple load points from measured MTr load current and PTr voltage, and the minimum distance classifier is adopted for the decision of fuzzy output membership function. To verify the effectiveness of the proposed strategy, Visual C++ MFC-based simulation environments is developed. Finally, the superiority the proposed strategy is proved by comparing the fuzzy ULTC operation control results based on multiple load center points with the existing ULTC operation control results based on fixed load center point using the data for three day.

• Journal of the Korea Society for Simulation
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• v.1 no.1
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• pp.1-16
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• 1992

This research develops two variance reduction methods for estimating the parameters of the experimental simulation model having multiple design points based on an approach focusing on reduction of the variances of the mean responses across multiple design points. The first method extends a combined approach of antithetic variates and control variates for a single design point to the multipopulation context with independent streams across the design points. The second method extends the same strategy in conjunction with the Schruben-Margolin method for improving the first method. We illustrate an example for implementing the second method. We expect these two approaches may improve the estimation of the parameters of interest compared with the control variates method.

• Smart Structures and Systems
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• v.30 no.1
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• pp.89-106
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• 2022

The negative stiffness of an active or semi-active damper system has been proven to be very effective in reducing dynamic response. Therefore, energy dissipation devices possessing negative stiffness, such as viscous inertial mass dampers (VIMDs), have drawn much attention recently. The control performance of the VIMD for cable vibration mitigation has already been demonstrated by many researchers. In this paper, a new optimal design procedure for VIMD parameters for taut cable vibration control is presented based on the fixed-points method originally developed for tuned mass damper design. A model consisting of a taut cable and a VIMD installed near a cable end is studied. The frequency response function (FRF) of the cable under a sinusoidal load distributed proportionally to the mode shape is derived. Then, the fixed-points method is applied to the FRF curves. The performance of a VIMD with the optimal parameters is subsequently evaluated through simulations. A taut cable model with a tuned VIMD is established for several cases of external excitation. The performance of VIMDs using the proposed optimal parameters is compared with that in the literature. The results show that cable vibration can be significantly reduced using the proposed optimal VIMD with a relatively small amount of damping. Multiple VIMDs are applied effectively to reduce the cable vibration with multi-modal components.

• Journal of the Korea Institute of Military Science and Technology
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• v.21 no.3
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• pp.323-330
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• 2018

In this paper, design and fabrication of a MSP(Multiple Scattering Points) discriminator for a simulated target measurement using a HRR(High Range Resolution) RADAR are described. The MSP discriminator is designed to provide a reference signal at the installed point on the simulated target in an outdoor test. The MSP discriminator is designed to have a remote control function that can turn the MSP discriminator on and off when the target moves to a remote location. While the MSP discriminator is off, the MSP discriminator is designed to be small enough not to spoil the target's unique RCS. The MSP discriminator consists of RF components in the Ku-band. In order to prevent spreading of the signal, a cable were added to the MSP discriminator to have an appropriate feedback loop delay considering the resolution of the RADAR. The fabricated MSP discriminator provided a reference scattering point as an RCS of approximately 1 dBsm. As a result, by using the MSP discriminator, the physical scattering points of the target were clearly identified in the measured signals with the RADAR.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.1
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• pp.291-304
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• 2019

This paper proposes a dynamic-tiling-based bandwidth-efficient (DTBE) virtual reality (VR) streaming scheme. We consider 360-degree VR contents with multiple view points such as the front, back, upper, and bottom sides. At a given time, the focus of a client is always bound to a certain view among multiple view points. By utilizing this perspective, under our proposed scheme, tiles with high encoding rates are selectively assigned to the focused view where multiple view points consist of multiple tiles with different encoding rates. The other tiles with low encoding rates are assigned to the remaining view points. Furthermore, for reducing view adaptation delay, we design a novel rapid view adaptation mechanism that selectively delivers an I-frame during view point updates by using frame indexing. We implement the proposed scheme on a commercial VR test bed where we adopt the MPEG media transport (MMT) standard with high-efficiency video coding (HEVC) tile modes. The measurement-based experiments show that the proposed scheme achieves an average data usage reduction of almost 65.2% as well as average view adaptation delay reduction of almost 57.7%.

• Journal of the Korean Institute of Gas
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• v.11 no.3
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• pp.13-18
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• 2007

The multivariate statistical analysis, using the multiple linear regression(MLR), have been applied to analyze and predict the flash points of binary systems. Prediction for the flash points of flammable substances is important for the examination of the fire and explosion hazards in the chemical process design. In this paper, the flash points are predicted by MLR based on the physical properties of pure substances and the experimental flash points data. The results of regression and prediction by MLR are compared with the values calculated by Raoult's law and Van Laar equation.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.529-535
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• 2008

Recently a rolling stock has been requiring more convenience facilities for passenger as well as satisfied the basic functions. The convenience facilities design take into consideration safety factor, convenience and easy accessible for disable passenger. In a point of view, convenience facilities should be considered and designed as well as related safety. This paper describes points to be considered on design with related to convenience facilities and safety factor of Diesel Multiple Unit for Intercity through the IRISH DMU.