• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.19 no.3
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• pp.320-326
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• 2009

The mechanical impedance and stiffness of the foundation of shipboard equipments and hulls supported by anti-vibration mount are very important so that the anti-vibration mount can accomplish its performance effectively. But, it is frequently argued how much stiffness and mechanical impedance are necessary for those foundations and hulls. In this research, it is discussed by evaluating the dynamic stiffness of the commercial anti-vibration mounts used in a naval vessel. Consequently, in this research, the minimum level of the mechanical impedance and stiffness of the foundation of shipboard equipments and hulls are suggested considering the dynamic stiffness of the mount which varies as frequency.

• Computers and Concrete
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• v.22 no.6
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• pp.501-514
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• 2018

The paper presents the thermo-mechanically induced non-linear response of multiwall carbon nanotube reinforced laminated composite beam (MWCNTRCB) supported by elastic foundation using higher order shear deformation theory and von-Karman non-linear kinematics. The elastic properties of MWCNT reinforced composites are evaluated using Halpin-Tsai model by considering MWCNT reinforced polymer matrix as new matrix by dispersing in it and then reinforced with E-glass fiber in an orthotropic manner. The laminated beam is supported by Pasternak elastic foundation with Winkler cubic nonlinearity. A generalized static analysis is formulated using finite element method (FEM) through principle of minimum potential energy approach.

• Clinics in Shoulder and Elbow
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• v.27 no.1
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• pp.18-25
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• 2024

Background: The Discovery Elbow System (DES) utilizes a polyethylene bearing within the ulnar component. An exchange bearing requires preoperative freezing and implantation within 2 minutes of freezer removal to allow insertion. We report our outcomes and experience using this technique. Methods: This was an analysis of a two-surgeon consecutive series of DES bearing exchange. Inclusion criteria included patients in which exchange was attempted with a minimum 1-year follow-up. Clinical and radiographic review was performed 1, 2, 3, 5, 8 and 10 years postoperative. Outcome measures included range of movement, Oxford Elbow Score (OES), Mayo Elbow Performance Score (MEPS), complications and requirement for revision surgery. Results: Eleven DESs in 10 patients were included. Indications were bearing wear encountered during humeral component revision (n=5); bearing failure (n=4); and infection treated with debridement, antibiotics and implant retention (DAIR; n=2). Bearing exchange was conducted on the first attempt in 10 cases. One case required a second attempt. One patient developed infection postoperatively managed with two-stage revision. Mean follow-up of the bearing exchange DES was 3 years. No further surgery was required, with no infection recurrence in DAIR cases. Mean elbow flexion-extension and pronosupination arcs were 107°(±22°) and 140° (±26°). Mean OES was 36/48 (±12) and MEPS was 83/100 (±19). Conclusions: Our results support the use of DES bearing exchange in cases of bearing wear with well-fixed stems or acute infection. This series provides surgeons managing DES arthroplasty with management principles, successful and reproducible surgical techniques and expected clinical outcomes in performing DES polyethylene bearing exchange. Level of evidence: IV.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.3 no.4
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• pp.43-51
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• 2000

This study was carried out to develop technologies of restoration and revegetation through monitoring the change of vegetation after setting up 3 type experimental sites on abandoned coal-mine lands. According to the results of 7 month's monitoring, sown species and a variety of invading species appeared at experimental sites. Moreover, the number of species, individuals and the ratio of coverage increased as time passed on. After 5 months, each experiment sites showed the result of successful revegetation. The most effective sites was treated by overspreading 1 cm loam soil on coal minesoil. As a result of this study, it is considered that the revegetation of abandoned coal-mine lands can be achieved effectively by making the minimum of foundation layer and improving the efficiency through mechanized construction. Besides, it is recommended to use native and early stage-succession species adapting themselves to coal minesoil, such as Gramineae, Leguminosae, Compositae and etc.

• Computers and Concrete
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• v.16 no.3
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• pp.429-448
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• 2015

The dams are huge structures storing a large amount of water and failures of them cause especially irreparable loss of lives during the earthquakes. They are named as a group of structures subjected to fluid-structure interaction. So, the response of the fluid and its hydrodynamic pressures on the dam should be reflected more accurately in the structural analyses to determine the real behavior as soon as possible. Different mathematical and analytical modelling approaches can be used to calculate the water hydrodynamic pressure effect on the dam body. In this paper, it is aimed to determine the dynamic response of concrete gravity dams using different water modelling approaches such as Westergaard, Lagrange and Euler. For this purpose, Sariyar concrete gravity dam located on the Sakarya River, which is 120km to the northeast of Ankara, is selected as a case study. Firstly, the main principals and basic formulation of all approaches are given. After, the finite element models of the dam are constituted considering dam-reservoir-foundation interaction using ANSYS software. To determine the structural response of the dam, the linear transient analyses are performed using 1992 Erzincan earthquake ground motion record. In the analyses, element matrices are computed using the Gauss numerical integration technique. The Newmark method is used in the solution of the equation of motions. Rayleigh damping is considered. At the end of the analyses, dynamic characteristics, maximum displacements, maximum-minimum principal stresses and maximum-minimum principal strains are attained and compared with each other for Westergaard, Lagrange and Euler approaches.

• Structural Engineering and Mechanics
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• v.64 no.4
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• pp.403-411
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• 2017

In this article, analytical solution for free vibration of micro composite laminated beam on elastic medium based on modified couple stress are presented. The surrounding elastic medium is modeled as the Winkler elastic foundation. The governing equations and boundary conditions are obtained by using the principle of minimum potential energy for EulerBernoulli beam. For investigating the effect of different parameters including material length scale, beam thickness, some numerical results on different cross ply laminated beams such as (90,0,90), (0,90,0), (90,90,90) and (0,0,0) are presented on elastic medium. Free vibration analysis of a simply supported beam is considered utilizing the Fourier series. Also, the fundamental frequency is obtained using the principle of Hamilton for four types of cross ply laminations with hinged-hinged boundary conditions and different beam theories. The fundamental frequency for different thin beam theories are investigated by increasing the slenderness ratio and various foundation coefficients. The results prove that the modified couple stress theory increases the natural frequency under the various foundation for free vibration of composite laminated micro beams.

• Earthquakes and Structures
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• v.10 no.6
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• pp.1429-1449
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• 2016

The effect of porosity on bending and free vibration behavior of simply supported functionally graded plate reposed on the Winkler-Pasternak foundation is investigated analytically in the present paper. The modified rule of mixture covering porosity phases is used to describe and approximate material properties of the FGM plates with porosity phases. The effect due to transverse shear is included by using a new refined shear deformation theory. The number of unknown functions involved in the present theory is only four as against five or more in case of other shear deformation theories. The Poisson ratio is held constant. Based on the sinusoidal shear deformation theory, the position of neutral surface is determined and the equation of motion for FG rectangular plates resting on elastic foundation based on neutral surface is obtained through the minimum total potential energy and Hamilton's principle. The convergence of the method is demonstrated and to validate the results, comparisons are made with the available solutions for both isotropic and functionally graded material (FGM). The effect of porosity volume fraction on Al/Al2O3 and Ti-6Al-4V/Aluminum oxide plates are presented in graphical forms. The roles played by the constituent volume fraction index, the foundation stiffness parameters and the geometry of the plate is also studied.

• Magazine of the Korean Society of Agricultural Engineers
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• v.16 no.4
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• pp.3611-3616
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• 1974

Alluvial plain of the coast of Kum river tail were found as being mostly consisted of weak foundation. The settlement of the ground, density and change of moisture content which were formed by the load due the construction of earth works were disclossed by the field investigations and laboratory tests. The results are as follow, 1) Banking materials are SM and soft soil stratum is CL. 2) Field moisture content; Wf=19-1.37c c; percentage of clay (less than 0.005mm) 3) optimum water content and maximum density of banking materials; rt=2.15$\mid$0.0165W(12%24%) 4) Density and moisture coutent of banking materials; rt=2.146-0.0095W (8%50%) 5) Density and moisture content of weak foundation; rt=2.06-0. 007W After construction (20%50%) Befor construction (40%60%) 6) Load and settlement of weak foundation; Everage settlement ratio; 12% of actual load p Maximum settlement ratio; 19% of actual load p Minimum settlement ratio: 5% of actual load p 7) Relation of cohesion and unconfined compression test value; c=1/2qu (qu<0.5kg/$\textrm{cm}^2$) c=1/3qu (qu<0.5kg/$\textrm{cm}^2$)

• Journal of The Korea Institute of Healthcare Architecture
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• v.23 no.1
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• pp.15-24
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• 2017

Purpose: Korea is expected to enter an aged society in 2018 and then a super-aged society in early 2025. The country's aging is progressing faster than any other country in the world. However, the foundation of the elderly friendly industry is weak, and measures at the government level are urgently needed. Especially, housing problems of the elderly are one of the most urgent measures to be taken. Korea does not have the minimum residential area standard for the elderly, and the current general minimum residential area standard is based on the survey of the housing situation without scientific evidence. Therefore, both standards need to be revised as soon as possible based on scientific evidence. Methods: The minimum residential area standard has been calculated following Karl H. E. Kroemer's Min or Max design also being called as-single cut and dual cut theory- as the maximum population value and minimum population value theory of Ernest J. McCormick. Therefore there is a need for a formula made using a few key factors, such as corresponding dimension, practical dimension, clearance, spare dimension, integrated dimension. These elements can be defined and used as formulas to calculate minimum residential area standards. Results: Assuming the results of the spatial variability in this study showed that it is possible to raise the standard of living in a terms of sustainable minimum size for the young, old and all residents. Implications: The government should set a minimum residential area standard with scientific grounds and set up a policy improving the life of people who live in an needy residential environment.

• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.1
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• pp.40-47
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• 2018

Porous walkway blocks are constructed for the purpose already, but reserved water is easily consumed due to the bigger permeability than necessary. Furthermore, porous structure reduces the strength of blocks, which resulting cracking and settlements in walkways. In this study, we suggested a solution for given problems by determination for the location of minimum principal stress in walkway blocks against moving foot loads in order to design and verifying the determined location of minimum principal stress. An optimum design with a verification example for determined location of minimum principal stress have been presented in a two dimensional Block member on elastic foundation for pedestrian walkway for reserving water inside. The minimum value for sum of shear forces is found when ${\times}1$ is 58.58 mm(30% of total span, 200mm), while the minimum deformation is located at ${\times}2=80mm$(70% of total span, 200 mm). In a modified model, When moving boundary condition(walkway foot loads) is located at ${\times}1$(=0 mm), the location of minimum principal stresses is found at 168 mm( 84% of span, 200 mm), in which the stress concentration due to the foot load is modeled as two layers of distributed loads(reactions of foundation modeled as springs). Consequently, zero deformed reservoirs for rainwater on the neutral axis (${\times}2=167mm$) has been determined in the modified model with three dimensional FEM analysis verifications.