• Wind and Structures
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• v.29 no.3
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• pp.177-194
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• 2019

While establishing adequate load paths in the light-frame wood structures is critical to maintain the overall structural integrity and avoid significant damage under extreme wind events, the understanding of the load paths is limited by the high redundant nature of this building type. The objective of the current study is to evaluate the system effects and investigate the load paths in the wood structures especially the older buildings for a better performance assessment of the existing building stock under high winds, which will provide guidance for building constructions in the future. This is done by developing building models with configurations that are suspicious to induce failure per post damage reconnaissance. The effect of each configuration to the structural integrity is evaluated by the first failure wind speed, amajor indicator beyond the linear to the nonlinear range. A 3D finite-element (FE) building model is adopted as a control case that is modeled using a validated methodology in a highly-detailed fashion where the nonlinearity of connections is explicitly simulated. This model is then altered systematically to analyze the effects of configuration variations in the model such as the gable end sheathing continuity and the gable end truss stiffness, etc. The resolution of the wind loads from scaled wind tunnel tests is also discussed by comparing the effects to wind loads derived from large-scale wind tests.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1994.10a
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• pp.49-54
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• 1994

A dynamic model for the cutting process in the end milling process is developed. This model, which describes the dynamic response of the end mill, the chip load geometry including tool runout, the dependence of the cutting forces on the chip load, is used to predict the dynamic cutting force during the end milling process. In order to predict accurately cutting forces and tool vibration, the model, which uses instantaneous specific cutting force, includes both regenerative effect and penetration effect. The model is verified through comparisons of model predicted cutting force with measured cutting forces obtained from machining experiments.

• Journal of Applied Reliability
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• v.16 no.2
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• pp.90-97
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• 2016

Purpose: Majority of bridges and roads in Gangwon Province have been carrying loads associated with heavy materials such as rocks, mining products, and cement. This location-specific live loads have contributed to the present situation of overloading, compared to other provinces in Korea. However, the bridges in Gangwon province are designed by national bridge design specification, without considering the location-specific live load characteristics. Therefore, this study focuses on the real traffic data accumulated on regional weighing station to verify the live load characteristics, including actual live load gross vehicle weight, axle weight axle spacings, and number of trucks. Methods: In order to take into account the location specific live load, a governmental weigh station (38th national highway Miro) have been selected and the passing truck data are processed. Based on the truck survey, trucks are categorized into 3 different shapes, and each shape has been idealized into normal distribution. Then, the resulting survey data are processed to predict the target maximum live load values, including the axle loads and gross vehicle weights in 75 years service life span. Results: The results are compared to the nationally used DB-24 live loads, and the results show that nationally recognized DB-24 live load does not sufficiently represent real traffic in mountaineous region in Gangwon province. Conclusion: The comparison results in the recommendation of location-specific live load that should be taken into account for bridge design and evaluation.

• Proceedings of the KIEE Conference
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• 1992.07a
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• pp.414-416
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• 1992

Stability analysis and load distribution problem of two coordinating robots using full dynamic model is studied in this paper. Dynamic models of two robots are combined with the position force control strategy and the Liapunov 2nd method is used for the proof of the stability. This analysis shows that the position and force control of two coordinating robot is always stable. Also, load distribution problem is mentioned with respect to the end-effector forces minimizing joint torques.

• Steel and Composite Structures
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• v.12 no.6
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• pp.523-540
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• 2012

It was clear from the former researches on reinforced concrete filled tubular steel (RCFT) structures that RCFT structures have different performance than concrete filled steel tubular (CFT) structures. However, despite of that, load-sharing ratio of RCFT is evaluating by the formula and range of CFT given by JSCE. Therefore, the aim of this investigation is to study the load-sharing ratio of RCFT columns subjected to axial compressive load by performing numerical simulations of RCFT columns with the nonlinear finite element analysis (FEA) program - ADINA. To achieve this goal, firstly proper material constitutive models for concrete, steel tube and reinforcement are proposed. Then axial compression tests of concrete, RC, CFT, and RCFT columns are carried out to verify proposed material constitutive models. Finally, by the plenty of numerical analysis with small-sized and big-sized columns, load-sharing ratio of RCFT columns was studied, the evaluation formulas and range were proposed, application of the formula was demonstrated, and following conclusions were drawn: The FEA model introduced in this paper can be applied to nonlinear analysis of RCFT columns with reliable results; the load-sharing ratio evaluation formula and range of CFT should not be applied to RCFT; The lower limit for the range of load-sharing ratio of RCFT can be smaller than that of CFT; the proposed formulas for load-sharing ratio of RCFT have practical mean in design of RCFT columns.

• Nuclear Engineering and Technology
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• v.52 no.1
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• pp.78-86
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• 2020

The operation and monitoring (OM) interface is the digital medium between nuclear power system and operators. The cognitive load of OM interface has an important effect on the operation errors made by operator during OM task between operator and computer. The cognitive load model of OM interface is constructed for analysing the composition and influencing factors of OM interface cognitive load. And to study the coping strategies and methods for cognitive load of nuclear power system. An experiment method based on eye movement is proposed to measure the cognitive load of OM interface. Experiment case is carried out with 20 subjects and typical OM interface of a nuclear power system simulator. The OM interface is optimized based on the experiment results. And the results comparison between the original OM interface and the optimized OM interface shows that the cognitive load model and proposed method is valuable contributions in reducing the cognitive load and improving the interaction efficiency of OM tasks.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.4C
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• pp.159-167
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• 2012

In this study, laboratory model pile-load test and finite element analysis were carried out to compare and analyze the strain behaviour around the model pile tip. In order to simulate the pile load, both the LCM(load control method)and DCM(displacement control method) were introduced to determine which one is appropriate for the FE simulation. In contrast to the previous simulation method, two interface elements around the model pile were used to consider the slip effect in the finite element analysis and its results were compared to the model test. Through this study it was found that the degree of non-associated flow was a dominant factor in terms of numerical solution convergence. In addition, an improved FE mesh was required to obtain the symmetric distribution of the maximum shear strain contour.

• Journal of Korean Society on Water Environment
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• v.33 no.6
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• pp.769-779
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• 2017

Nutrient (i.e., nitrogen and phosphorus) budgets are required under a 'Livestock Excreta Survey'. A nutrient budget is one of the agri-environmental indicators that calculates the difference between the inputs and outputs of the amount of nutrients within a certain boundary and for a certain time period (e.g., 1 year). In this study, a nutrients budget model was developed to effectively determine the surplus of nutrients within a region in Korea. The C# program language was used in order to facilitate the deployment of a graphical user interface (GUI) and to enhance compatibility. Also, the model was developed on Windows OS, which is the commonly used operating system in Korea. The model was based on the OECD/Eurostat nutrient budget method, and it was modified to consider manure composting procedures as well. There are key features of the nutrient budget model, including directly use of the original data sets from various input and output sources, and a collectively exchange of the address in different formats. The model can quickly show the results of various spatial and temporal resolutions with the same data, as well as perform a sensitivity analysis with coefficients and easily compareresults using tables and graphs. Further, it would be necessary to study the extension of the scope of utilization, such as the application of various nutrient budget methods. It would also be helpful to investigate both pre and postprocessing information such as linking input data through online systems.

• Smart Structures and Systems
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• v.31 no.3
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• pp.275-281
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• 2023

In recent years, technological developments have rapidly increased the number of complex structures and equipment in the industrial. Accordingly, the prognostics and health monitoring (PHM) technology has become significant. The safety assessment of industrial sites requires data obtained by installing a number of sensors in the structure. Therefore, digital twin technology, which forms the core of the Fourth Industrial Revolution, is attracting attention in the safety field. The research on digital twin technology of structures subjected to seismic loads has been conducted recently. Hence, this study proposes a digital twin system that estimates the responses and arbitrary load in real time by utilizing the minimum sensor to a pipe that receives a seismic and arbitrary load. To construct the digital twin system, a finite-element model was created considering the dynamic characteristics of the pipe system, and then updating the finite-element model. In addition, the calculation speed was improved using a finite-element model that applied the reduced-order modeling (ROM) technology to achieve real-time performance. The constructed digital twin system successfully and rapidly estimated the load and the point where the sensor was not attached. The accuracy of the constructed digital twin system was verified by comparing the response of the digital twin model with that derived by using the load estimated from the digital twin model as input in the finite-element model.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.187-188
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• 2011

This paper proposes the hybrid Complex-PSO algorithm based on the complex search method and particle swarm optimization (PSO) for unconstrained optimization. This hybridization intends to produce faster and more accurate convergence to the optimum value. These hybrid will concentrate on determining the dynamic load model parameters, the ZIP model and induction motor model parameters. Measurement-based parameter estimation, which employs measurement data to derive load model parameters, is used. The theoretical foundation of the measurement-based approach is system identification. The main objective of this paper is to demonstrate how the standard particle swarm optimization and complex method can be improved through hybridization of the two methods and the results will be compared with that of their original forms.