• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.25 no.6
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• pp.462-470
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• 2016

The locking load of a conventional manhole depends on the weight of its cover. Locking-type manhole structures with a special locking mechanism were recently developed to prevent accidents such as stolen cover, away cover from a frame. The weight of the manhole structure can be reduced under structural safety because the locking force of a locking-type manhole is greater than the weight of the cover. A light-weight manhole cover is developed in this study by using a finite element stress analysis and the design of experiments. Static stress analysis and fracture experiments are also conducted to analyze the states of the initial product. The optimum light-weight manhole cover considering manufacturing molds is developed and tested. Consequently, the weight was found to reduce by 16%. In addition, the fracture load increased by 38%.

• Computational Structural Engineering
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• v.24 no.2
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• pp.43-50
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• 2011

• Structural Engineering and Mechanics
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• v.20 no.1
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• pp.85-110
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• 2005

This paper aims at formulating various statistical models for the study of a ten year Weigh-in-Motion (WIM) data collected from various WIM stations in Hong Kong. In order to study the bridge live load model it is important to determine the mathematical distributions of different load affecting parameters such as gross vehicle weights, axle weights, axle spacings, average daily number of trucks etc. Each of the above parameters is analyzed by various stochastic processes in order to obtain the mathematical distributions and the Maximum Likelihood Estimation (MLE) method is adopted to calculate the statistical parameters, expected values and standard deviations from the given samples of data. The Kolmogorov-Smirnov (K-S) method of approach is used to check the suitability of the statistical model selected for the particular parameter and the Monte Carlo method is used to simulate the distributions of maximum value stochastic processes of a series of given stochastic processes. Using the statistical analysis approach the maximum value of gross vehicle weight and axle weight in bridge design life has been determined and the distribution functions of these parameters are obtained under both free-flowing traffic and dense traffic status. The maximum value of bending moments and shears for wide range of simple spans are obtained by extrapolation. It has been observed that the obtained maximum values of the gross vehicle weight and axle weight from this study are very close to their legal limitations of Hong Kong which are 42 tonnes for gross weight and 10 tonnes for axle weight.

• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.1
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• pp.51-58
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• 2021

As vertical extension remodeling policy was implemented in 2014, Safety Inspection Manual was established to ensure structural safety during the vertical extension remodeling. In the manual, the story weight for capability evaluation was based on the Safety Inspection Manual for Reconstruction. Although capability evaluation in the vertical extension remodeling is more important than reconstruction, engineering basis for the story weight is insufficient. Therefore it is necessary to improve the method of calculating the story weight. In this study, story importance and story weight were defined through the case analysis of capability evaluation in order to provide engineering basis for story weight. Also, new story weight equation was presented considering the load-bearing ratio of structural members.

• Geomechanics and Engineering
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• v.11 no.4
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• pp.493-513
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• 2016

A modified grey clustering method is presented to systematically evaluate the risk of water inrush in karst tunnels. Based on the center triangle whitenization weight function and upper and lower limit measure whitenization weight function, the modified grey evaluation model doesn't have the crossing properties of grey cluster and meets the standard well. By adsorbing and integrating the previous research results, seven influence factors are selected as evaluation indexes. A couple of evaluation indexes are modified and quantitatively graded according to four risk grades through expert evaluation method. The weights of evaluation indexes are rationally distributed by the comprehensive assignment method. It is integrated by the subjective factors and the objective factors. Subjective weight is given based on analytical hierarchy process, and objective weight obtained from simple dependent function. The modified grey evaluation model is validated by Jigongling Tunnel. Finally, the water inrush risk of Shangjiawan Tunnel is evaluated by using the established model, and the evaluation result obtained from the proposed method is agrees well with practical situation. This risk assessment methodology provides a powerful tool with which planners and engineers can systematically assess the risk of water inrush in karst tunnels.

• Journal of the Korean Society for Precision Engineering
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• v.26 no.12
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• pp.102-109
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• 2009

This study proposes the structural optimization of a manifold valve. FE analysis is performed to evaluate the strength of a manifold valve. In addition, the structural optimization technique is applied to reduce its weight. In this study, the optimization method using the kriging interpolation method is adopted to obtain the minimum weight satisfying the strength constraint. The maximum stress and the weight are replaced by the metamodels. In this process, tile sample points are generated by latin-hypercube design. Optimum designs are obtained by ANSYS Workbench and the in-house program.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.2
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• pp.153-159
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• 2004

A control-structure combined optimal design problem is discussed taking a 3-D truss structure as a design object. We use descriptor forms for a controlled object and a generalized plant because the structural parameters appear naturally in these forms. We consider not only minimum weight design problem for structure system, but also suppression problem of the effect of disturbances for control system as the purpose of the design. By minimizing the linear sum of the normalized structural objective function and control objective function, it is possible to make optimal design by which the balance of the structural weight and the control performance is taken.

• Journal of the Korea institute for structural maintenance and inspection
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• v.4 no.4
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• pp.211-218
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• 2000

Many bridges are severely damaged by the overloaded heavy vehicle and the trend will become more serious because the traffic volume is continuously increasing. Currently, the vehicles with gross weights over 40 tonf or axle weight over 10 tonf are not allowed on the public road. However, this regulation is not based on a systematic study on the bridge capacity and assumed to be much too conservative depending on the vehicle types and bridge types. In this study, the permit weights of heavy vehicles of diverse axle spacings and axle load distribution are calculated considering the structural characteristics of bridge superstructures. In order to consider the various load effects of heavy weight vehicle crossings, three conditions are considered in the calculation of permit vehicle load. From the results, the permit vehicle weights of the simple girder bridges are calculated.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.18 no.1
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• pp.103-109
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• 2009

This paper presents structural design optimization of a micro milling machine for minimum weight and compliance using a genetic algorithm with dynamic penalty function. The optimization procedure consists of two design stages, which are the static and dynamic design optimization stages. The design problem, in this study, is to find out thickness of structural members which minimize the weight, the static compliance and the dynamic compliance of the micro milling machine under several constraints such as dimensional constraints, maximum compliance limit, and safety factor criterion. Optimization results showed a great reduction in the static and dynamic compliances at the spindle nose of the micro milling machine in spite of a little decrease in the machine weight.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1999.04a
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• pp.203-209
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• 1999

In this study, the structural deflection analysis of robot manipulator for removing nuclear fuel rod from nuclear reactor vessel is performed by using general purpose finite element code (ANSYS). The structural deflection analysis results reported in this study is very required for the accurate design of robot system. The structural deflection analysis for the manipulator's structural status at which the gripper grasps and draws up the nuclear fuel rod is done, For this beginning structural status of robot manipulator's removing motion, the reaction forces at each joint have static maximum values as reported in the reference(6), and so these forces may cause the maximum deflection of robot structure. The structural deflection analysis is performed for selected four working cases of the proposed structural model and results on deformation, stress for the manipulator's solid body and the deflection at the end of robot manipulator's gripper are calculated. And further, the same analysis is performed for the slenderer manipulator with cross section reduced by one-fifth of each side length of proposed model. The analysis is performed not only for the nuclear fuel rod with weight load of 300kg but also for nuclear fuel rods with weight loads of 100kg, 200kg, 400kg and 500kg. The static structural deflection analysis results show that the deflection value increases as the load increases and the largest value (corresponding to the weight load of 500kg in case 1) is much smaller than the gap distance between nuclear fuel rods. but the largest value for the slenderer manipulator is almost as large as the gap distance, Hence, conclusively, the proposed manipulator's structural model is acceptably safe for mechanical design of robot system.