• Korean Journal of Computational Design and Engineering
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• v.16 no.1
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• pp.1-10
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• 2011

In this paper, we propose an AR-based tangible interaction using a finger fixture for virtual evaluation of digital handheld products. To realize tangible interaction between a user and a product in a computer-vision based AR environment, we uses two types of tangible objects: a product-type object and a finger fixture. The product-type object is used to acquire the position and orientation of the product, and the finger fixture is used to recognize the position of a finger tip. The two objects are fabricated by RP technology and AR markers are attached to them. The finger fixture is designed to satisfy various requirements with an ultimate goal that the user holding the finger fixture in his or her index finger can create HMI events by touching specified regions (buttons or sliders) of the product-type object with the finger tip. By assessing the accuracy of the proposed interaction, we have found that it can be applied to a wide variety of digital handheld products whose button size is not less than 6 mm. After performing the design evaluation of several handheld products using the proposed AR-based tangible interaction, we received highly encouraging feedback from users since the proposed interaction is intuitive and tangible enough to provide a feeling like manipulating products with human hands.

• Structural Engineering and Mechanics
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• v.20 no.5
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• pp.575-587
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• 2005

Using the nonlinear load transfer function for pile side soil and the linear load transfer function for pile end soil, a combined approach of the incremental load transfer matrix method and the approximate differential equation solution method is presented for the nonlinear analysis of interaction between flexible pile group and soil. The proposed method provides an effective approach for the solution of the nonlinear interaction between flexible pile group under rigid platform and surrounding soil. To verify the accuracy of the proposed method, a static load test for a nine-pile group under a rigid platform is carried out. The finite element analysis is also conducted for comparison purposes. It is found that the results from the proposed method match very well with those from the experimental test and are better in comparison with the finite element method.

• Wind and Structures
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• v.19 no.1
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• pp.35-58
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• 2014

A numerical simultaneous solution involving a linear elastic model was applied to study the fluid-structure interaction (FSI) of membrane structures under wind actions, i.e., formulating the fluid-structure system with a single equation system and solving it simultaneously. The linear elastic model was applied to managing the data transfer at the fluid and structure interface. The monolithic equation of the FSI system was formulated by means of variational forms of equations for the fluid, structure and linear elastic model, and was solved by the Newton-Raphson method. Computation procedures of the proposed simultaneous solution are presented. It was applied to computation of flow around an elastic cylinder and a typical FSI problem to verify the validity and accuracy of the method. Then fluid-structure interaction analyses of a saddle membrane structure under wind actions for three typical cases were performed with the method. Wind pressure, wind-induced responses, displacement power spectra, aerodynamic damping and added mass of the membrane structure were computed and analyzed.

• Interaction and multiscale mechanics
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• v.6 no.1
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• pp.51-81
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• 2013

A wide literature review on Static Soil-Structure-Interaction (SSI) is done to highlight the key impacts of soil complexity on structural members of framed structures. Attention is paid to the developed approaches, i.e., conventional and Finite Element Method (FEM), to emphasize on deficiencies and merits of the proposed methods according to their applicability, accuracy and power to model and idealization of the superstructures as well as the soil continuum. Proposed hypothesis are much deeply discussed herein for better understanding which is normally neglected in literature review papers due to the large number of references and limit of space.

• International Journal of Internet, Broadcasting and Communication
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• v.14 no.3
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• pp.143-148
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• 2022

In this paper, we employ deep neural network (DNN) to discern Android user interaction data distribution from artificial data distribution. We utilize real Android user interaction trace dataset collected from [1] to evaluate our DNN design. In particular, we use sequential model with 4 dense hidden layers and 1 dense output layer in TensorFlow and Keras. We also deploy sigmoid activation function for a dense output layer with 1 neuron and ReLU activation function for each dense hidden layer with 32 neurons. Our evaluation shows that our DNN design fulfills high test accuracy of at least 0.9955 and low test loss of at most 0.0116 in all cases of artificial data distributions.

• 한국전산유체공학회:학술대회논문집
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• 2006.10a
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• pp.24-25
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• 2006

An unstructured mesh method has been developed for the simulation of steady and time-accurate flows around helicopter rotors. A dynamic and quasi-unsteady solution-adaptive mesh refinement technique was adopted for the enhancement of the solution accuracy in the local region of interest involving highly vortical flows. Applications were made to the 2-D blade-vortex interaction aerodynamics and the 3-D rotor blades in hover. The interaction between the rotor and the airframe in forward flight was investigated by introducing an overset mesh technique.

• KIPS Transactions on Software and Data Engineering
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• v.12 no.7
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• pp.315-324
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• 2023

A simple and accurate whole body rehabilitation interaction technology using immersive digital content is needed for elderly patients with steadily increasing age-related diseases. In this study, we introduce whole-body interaction technology using HoloLens and Kinect for this purpose. To achieve this, we propose three coordinate transformation methods: mesh feature point-based transformation, AR marker-based transformation, and body recognition-based transformation. The mesh feature point-based transformation aligns the coordinate system by designating three feature points on the spatial mesh and using a transform matrix. This method requires manual work and has lower usability, but has relatively high accuracy of 8.5mm. The AR marker-based method uses AR and QR markers recognized by HoloLens and Kinect simultaneously to achieve a compliant accuracy of 11.2mm. The body recognition-based transformation aligns the coordinate system by using the position of the head or HMD recognized by both devices and the position of both hands or controllers. This method has lower accuracy, but does not require additional tools or manual work, making it more user-friendly. Additionally, we reduced the error by more than 10% using RANSAC as a post-processing technique. These three methods can be selectively applied depending on the usability and accuracy required for the content. In this study, we validated this technology by applying it to the "Thunder Punch" and rehabilitation therapy content.

• Wind and Structures
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• v.22 no.3
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• pp.349-368
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• 2016

A preconditioning technique is presented for a simultaneous solution to wind-membrane interaction. In the simultaneous equations, a linear elastic model was employed to deal with the fluid-structure data transfer at the interface. A Lagrange multiplier was introduced to impose the specified boundary conditions at the interface and strongly coupled simultaneous equations are derived after space and time discretization. An initial linear elastic model preconditioner and modified one were derived by treating the linearized elastic model equation as a saddle point problem, respectively. Accordingly, initial and modified fluid-structure interaction (FSI) preconditioner for the simultaneous equations were derived based on the initial and modified linear elastic model preconditioners, respectively. Wind-membrane interaction analysis by the proposed preconditioners, for two and three dimensional membranous structures respectively, was performed. Comparison was made between the performance of initial and modified preconditioners by comparing parameters such as iteration numbers, relative residuals and convergence in FSI computation. The results show that the proposed preconditioning technique greatly improves calculation accuracy and efficiency. The priority of the modified FSI preconditioner is verified. The proposed preconditioning technique provides an efficient solution procedure and paves the way for practical application of simultaneous solution for wind-structure interaction computation.

• Computers and Concrete
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• v.19 no.5
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• pp.545-553
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• 2017

In the authors' previous study, an axial force-flexural moment (P-M) interaction curve model was proposed to evaluate fire-resisting performances of reinforced concrete (RC) column members. The proposed method appeared to properly consider the axial and flexural strength degradations including the secondary moment effects in RC columns due to fire damage. However, the detailed P-M interaction curve model proposed in the authors' previous study requires somewhat complex computational procedures and iterative calculations, which makes it difficult to be used for practical design in its current form. Thus, the aim of this study was to develop a simplified P-M interaction curve model of RC columns exposed to fire considering the effects of fire damage on the material performances and magnitudes of secondary moments. The simplified P-M interaction model proposed in this study was verified using 66 column fire test results collected from literature, and the verification results showed that the proposed simplified method can provide an adequate analysis accuracy of the failure loads and fire-resisting times of the RC column specimens.

• Steel and Composite Structures
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• v.12 no.1
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• pp.73-92
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• 2012

The effect of element interaction and material nonlinearity on the ultimate capacity of stainless steel plated cross-sections is investigated in this paper. The focus of the research lies in cross-sections failing by local buckling; member instabilities, distortional buckling and interactions thereof with local buckling are not considered. The cross-sections investigated include rectangular hollow sections (RHS), I sections and parallel flange channels (PFC). Based on previous finite element investigations of structural stainless steel stub columns, parametric studies were conducted and the ultimate capacity of the aforementioned cross-sections with a range of element slendernesses and aspect ratios has been obtained. Various design methods, including the effective width approach, the direct strength method (DSM), the continuous strength method (CSM) and a design method based on regression analysis, which accounts for element interaction, were assessed on the basis of the numerical results, and the relative merits and weaknesses of each design approach have been highlighted. Element interaction has been shown to be significant for slender cross-sections, whilst the behaviour of stocky cross-sections is more strongly influenced by the material strain-hardening characteristics. A modification to the continuous strength method has been proposed to allow for the effect of element interaction, which leads to more reliable ultimate capacity predictions. Comparisons with available test data have also been made to demonstrate the enhanced accuracy of the proposed method and its suitability for the treatment of local buckling in stainless steel cross-sections.