• Earthquakes and Structures
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• v.8 no.5
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• pp.1171-1190
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• 2015

Enhancement of strength and ductility is the main reason for the extensive use of FRP jackets to provide external confinement to reinforced concrete columns especially in seismic areas. Therefore, numerous researches have been carried out in order to provide a better description of the behavior of FRP-confined concrete for practical design purposes. This study presents a new approach to obtain strength enhancement of CFRP (carbon fiber reinforced polymer) confined concrete cylinders by applying artificial neural networks (ANNs). The proposed ANN model is based on experimental results collected from literature. It represents the ultimate strength of concrete cylinders after CFRP confinement which is also given in explicit form in terms of geometrical and mechanical parameters. The accuracy of the proposed ANN model is quite satisfactory when compared to experimental results. Moreover, the results of the proposed ANN model are compared with five important theoretical models proposed by researchers so far and considered to be in good agreement.

• Proceedings of the Korean Society of Veterinary Clinics Conference
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• 2007.05a
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• pp.137-137
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• 2007

• Structural Engineering and Mechanics
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• v.50 no.6
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• pp.853-862
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• 2014

In this paper, two approximate analytical methods have been applied to forced nonlinear vibration problems to assess a high accurate analytical solution. Variational Iteration Method (VIM) and Perturbation Method (PM) are proposed and their applications are presented. The main objective of this paper is to introduce an alternative method, which do not require small parameters and avoid linearization and physically unrealistic assumptions. Some patterns are illustrated and compared with numerical solutions to show their accuracy. The results show the proposed methods are very efficient and simple and also very accurate for solving nonlinear vibration equations.

• Structural Engineering and Mechanics
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• v.51 no.2
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• pp.349-360
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• 2014

In this study, three approximate analytical methods have been proposed to prepare an accurate analytical solution for nonlinear oscillators with fractional potential. The basic idea of the approaches and their applications to nonlinear discontinuous equations have been completely presented and discussed. Some patterns are also presented to show the accuracy of the methods. Comparisons between Energy Balance Method (EBM), Variational Iteration Method (VIM) and Hamiltonian Approach (HA) shows that the proposed approaches are very close together and could be easily extend to conservative nonlinear vibrations.

• Structural Engineering and Mechanics
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• v.51 no.3
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• pp.519-530
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• 2014

This paper attempts to investigate the nonlinear dynamic analysis of strong nonlinear problems by proposing a new analytical method called Hamiltonian Approach (HA). Two different cases are studied to show the accuracy and efficiency of the method. This approach prepares us to obtain the nonlinear frequency of the nonlinear systems with the first order of the solution with a high accuracy. Finally, to verify the results we present some comparisons between the results of Hamiltonian approach and numerical solutions using Runge-Kutta's [RK] algorithm. This approach has a powerful concept and the high accuracy, so it can be apply to any conservative nonlinear problems without any limitations.

• Computers and Concrete
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• v.20 no.1
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• pp.57-63
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• 2017

A coupled experimental-numerical study on shear fracture in concrete specimens with different geometries is carried out. The crack initiation, propagation and final breakage of concrete specimens are experimentally studied under compression loading. The load-strain and the strength of the specimens are experimentally measured, indicating decreasing effects of the shear behavior on the failure load of the specimen. The effects of specimen geometries on the shear fracturing path in the concrete specimens are also investigate. Numerical models using an indirect boundary element method are made to evaluate the crack propagation paths of concrete specimens. These numerical results are compared with the performed experiments and are validated experimentally.

• Structural Engineering and Mechanics
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• v.64 no.3
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• pp.329-337
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• 2017

This study concerns the vibrational behavior of multi-walled nested silicon-carbide and carbon nanotubes using the finite element method. The beam elements are used to model the carbon-carbon and silicon-carbon bonds. Besides, spring elements are employed to simulate the van der Waals interactions between walls. The effects of nanotube arrangement, number of walls, geometrical parameters and boundary conditions on the frequencies of nested silicon-carbide and carbon nanotubes are investigated. It is shown that the double-walled nanotubes have larger frequencies than triple-walled nanotubes. Besides, replacing silicon carbide layers with carbon layers leads to increasing the frequencies of nested silicon-carbide and carbon nanotubes. Comparing the first ten mode shapes of nested nanotubes, it is observed that the mode shapes of armchair and zigzag nanotubes are almost the same.

• Annual Conference of KIPS
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• 2000.10a
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• pp.481-484
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• 2000

본 논문에서는 현 교육의 문제점을 해결하고 학생들 개개인의 특기.적성을 살릴 수 있는 특별활동 프로그램에 있어 기존의 방식인 손으로 직접 작업을 하던 특별활동 부서 배정 방식을 향후 교육환경의 변화 추세에 맞추어 학교 안에서 이루어지는 교육활동을, 시간적 공간적 제약을 벗어나 자유로운 공간에서 학생 임의로 특별활동 부서를 신청, 자동 배정할 수 있도록 PHP 와 MySQL을 이용하여 시스템을 구축함으로써, 학생들에게는 정보화 교육의 극대화를 꾀하였고, 교사에게는 조직 편성 운영의 시간과 경비를 줄임으로서 교수-학습의 질을 향상시킬 수 있는 방향을 제시한다.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.26 no.1
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• pp.75-89
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• 2016

Objectives: The purpose of this study was to investigate job stress and satisfaction by general characteristics of engineers industrial hygiene management, and we expect to provide basic data for strategic plan to strengthen the role related to the job. Methods: The subjects of this study was 184 persons who belong to the Korean Industrial Health Association, and 178 completed questionnaires were analyzed. The survey was conducted from June 29 to July 3, 2015. Conclusions: It is necessary to decrease the stress caused by additional job through increasing manpower and developing detailed manual according to the position and systematic job assignment considering general characteristics. Also, it is judged that job satisfaction should increase by vitalizing mentoring, club, small group activity in workplace for maintaining and improving good personal relationship with team members, and implementing incentive system to acknowledge and reward personal duty result.

• Ocean Systems Engineering
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• v.5 no.1
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• pp.31-40
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• 2015

Three dimensional (3D) non-linear finite element analysis of offshore pipeline is investigated in this work with the help of general purpose software Abaqus. The general algorithm for the finite element approach is introduced. The 3D seabed mesh, limited to a corridor along the pipeline, is extracted from survey data via Fledermous software. Moreover soil bearing capacity and coefficient of frictions, obtained from the field survey report, and are introduced into the finite element model through the interaction module. For a case of study, a 32inch pipeline with API 5L X65 material grade subjected to high pressure and high temperature loading is investigated in more details.