• Structural Engineering and Mechanics
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• v.46 no.1
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• pp.91-110
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• 2013

This paper proposes a novel iterative procedure for the design of planar reinforced concrete structures in which the reinforcement is designed for stresses calculated in a nonlinear finite element analysis. The procedure is intended as an alternative to strut and tie modeling for the design of complex structures like deep beams with openings. Practical reinforcement arrangements are achieved by grouping the reinforcement into user defined horizontal and vertical bands. Two alternative strategies are proposed for designing the reinforcement which are designated A and B. Design constraints are specified in terms of permissible stresses and strains in the reinforcement and strains in the concrete. A case study of a deep beam with an opening is presented to illustrate the method. Comparisons are made between design strategies A and B of which B is shown to be most efficient. The resulting reinforcement weights are also shown to compare favorably with those previously reported in the literature.

• Composites Research
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• v.15 no.1
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• pp.9-20
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• 2002

In this study, the design method of filament wound composite pressure tanks was established by using finite element analyses. Pressure tanks were designed with and without a load sharing metallic liner. A GUI(graphic user interface) program was developed to increase the efficiency of analyses. The replacement ratio was defined in order to replace a metal pressure tank with a composite one. Finally, the best design model that is satisfied with design requirements was suggested.

• Transactions of Materials Processing
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• v.22 no.6
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• pp.303-309
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• 2013

Spring-back of MS1470 steel sheets was numerically predicted using a non-linear kinematic hardening material behavior based on the Yoshida-Uemori model. From uniaxial tension and uniaxial tension-compression-tension data as well as the uniaxial tension-unloading-tension data, the parameters of the Yoshida-Uemori model were obtained. For the numerical simulations, the Yoshida-Uemori model was implemented into the commercial finite element program, ABAQUS/Explicit and ABAQUS/Standard using the user-defined material subroutines. The model performance was validated against the measured spring-back from the benchmark problems of NUMISHEET 2008 and NUMISHEET 2011, the 2-D draw bending test and the S-rail forming test, respectively.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.5
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• pp.599-604
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• 2019

This study examined how the characteristics of smartphone affect the functional performance of smartphones. In particular, this study focused on an understanding of the correlation between smartphone functional factors and usage habits. Functionality is defined as 11 kinds of functional elements. The characteristics of the smartphones were defined as the hardware characteristics and the user habits characteristics. Eighty subjects were organized to collect actual data by the smartphone function. The actual time required to perform each function was measured and observed five times for each functional element. Regression analysis was performed using Minitab ver.14 by classifying the measured values of the functional elements as dependent variables, the hardware characteristics collected through the questionnaire, and the user's usage habits as 12 independent variables. Overall, it is difficult to conclude that demographic and hardware characteristics of smartphone users have a significant effect on the performance. On the other hand, the variables related to smartphone usage habits have had a great impact on the performance of smartphone tasks, and as a result, the task execution time has increased. In simple input variables or viewing variables, the effects on usability was relatively small, but in all active variables, the execution time increased 10% - 30% in all tasks except for phone calls, seeking phone numbers, and dictionary search. Thus far, if the smartphone user interface has been provided uniformly in a large and simple manner, users with various usage habits can be utilized even if the input method and task processing method are more complicated and various interface types are provided.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.28 no.1
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• pp.1-8
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• 2015

In this paper, computational evaluation method for fatigue crack growth rate(FCGR) based on material viscoplastic-damage model is proposed. Viscoplastic-damage model expressing material constitutive behavior of 7% nickel steel is introduced and is implemented into commercial finite element analysis(FEA) code, ABAQUS, as a user defined material subroutine(UMAT) for application in the FEA environments. Verification of developed UMAT and material parameters of material model are carried out by uniaxial tensile test simulations of 7% nickel steel. Moreover, jump-in-cycles procedure and rearrangement of critical damage are employed and also implemented to the ABAQUS UMAT for fatigue damage analysis. Typical FCGR test results such as relationship between crack length and number of cycles and relationship between da/dN and ${\Delta}K$ could be obtained from FCGR test simulation using developed UMAT and these results are compared with experimental results in order to verify of proposed computational method.

• Journal of Navigation and Port Research
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• v.37 no.1
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• pp.9-14
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• 2013

The e-navigation has been being developed in IMO is a sort of strategy to provide user-oriented services for safe navigation and environmental protection based on the architecture and its related services complying with the user needs. At NAV $57^{th}$ meeting in 2011, the overarching e-navigation architecture was approved which represent overall relationship only between onboard and ashore elements, so more detail technical architecture for each element should be developed for implementation in view of services and systems. Considering the continuous and iterative verification of e-navigation development process required by IMO, the relationship and traceability should be took in consideration between the outcome of e-navigation process and the element of the architecture. In this paper, we have surveyed literarily the user needs, result of gap analysis and practical solutions to address them and defined the architecture elements and their relationship considering the three kinds of views of DoDAF(Architecture Framework) of US department of Defence, in result, proposed the e-navigation shipboard technical architecture.

• 한국HCI학회:학술대회논문집
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• 2008.02b
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• pp.268-273
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• 2008

This work defines user intention according to intention range, and also proposes an interactive sound installation which reflects and varies above features. User intention consists of several decomposition concepts, which are elemental intentions, partial intentions, and a universal intention. And also, each concept is defined as inclusion/affiliation relationship with other concepts. For the representation of elemental intention, we implemented an musical interface, Color note, which represents the colors and notes according to response of participants. We also propose Harmonic Defragmentation (HD), which arranges the partial intentions with harmonic rule. Finally, the universal intention is inferred to the comprehensive direction of elemental intentions. We used Karhunen-Lo$\`{e}$ve(K-L) Transform for the inference. For verifying the validity of our proposed interface, the "Color Note," and the various techniques, we installed our work and surveyed various users for the evaluation of HD and statistical techniques. Also, we commissioned another survey to find out satisfaction measurement which was used for expressing universal intention.

• Computers and Concrete
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• v.24 no.3
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• pp.207-222
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• 2019

This paper has presented an effective and accurate meso-scale finite element model for simulating the fracture process of concrete under compression-shear loading. In the proposed model, concrete is parted into four important phases: aggregates, cement matrix, interfacial transition zone (ITZ), and the initial defects. Aggregate particles were modelled as randomly distributed polygons with a varying size according to the sieve curve developed by Fuller and Thompson. With regard to initial defects, only voids are considered. Cohesive elements with zero thickness are inserted into the initial mesh of cement matrix and along the interface between aggregate and cement matrix to simulate the cracking process of concrete. The constitutive model provided by ABAQUS is modified based on Wang's experiment and used to describe the failure behaviour of cohesive elements. User defined programs for aggregate delivery, cohesive element insertion and modified facture constitutive model are developed based on Python language, and embedded into the commercial FEM package ABAQUS. The effectiveness and accuracy of the proposed model are firstly identified by comparing the numerical results with the experimental ones, and then it is used to investigate the effect of meso-structure on the macro behavior of concrete. The shear strength of concrete under different pressures is also involved in this study, which could provide a reference for the macroscopic simulation of concrete component under shear force.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.29 no.2 s.233
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• pp.253-261
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• 2005

In decades, a substantial body of work on a unified viscoplastic model which considers the mechanism of plastic deformation and creep deformation has developed. The systematic scheme for numerical analysis of unified model is necessary because the dominant failure mechanism is the defect growth and coalescence in materials. In the present study, the unified viscoplastic model for materials with defects suggested by Suquet and Michel was employed for numerical analysis. The constitutive equations are integrated based on the generalized mid-point rule and implemented into a finite element program (ABAQUS) by means of user-defined subroutine (UMAT). To evaluate the validity of the developed UMAT code and the assessment of the adopted viscoplastic model, the results obtained from the UMAT code was compared with the numerical reference solution and experimental data. The unit cell analysis also has been investigated to study the effect of strain rate, temperature, stress triaxiality and initial defect volume fraction on the growth and coalescence of the defect.

• The Journal of the Korea institute of electronic communication sciences
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• v.8 no.12
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• pp.1911-1916
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• 2013

One significant challenge that arises in social tagging systems is the rapid increase in the number and diversity of the tags. As opposed to structured annotation systems, tags provide users an unstructured, open-ended mechanism to annotate and organize web-content. In this paper, we propose a scheme for URL recommendation that is based on a folksonomy which is comprised of user-defined tags, URL-keywords and the category folder name as the major element. This scheme will be further improved and implemented on a browser extension that recommends to users the best way to classify a particular URL.