• KSCE Journal of Civil and Environmental Engineering Research
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• v.37 no.3
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• pp.521-529
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• 2017

In this study, analyzed the effective width of concrete unfilled composite steel grid deck which has different shear connector details from that of composite bridge. The effective width of concrete unfilled composite steel grid deck according to effective width calculation method, load size and main bearing bar spacing-span ratio was evaluated. As a result of analysis, it is analyzed that the effective width is calculated to be nearly equal to the actual effective width by idealizing the stress shape as a trapezoidal shape. In addition, shear hole penetration reinforcing bars applied to increase the shear strength is shown to increase the effective width. From the results of the analysis of the effective width according to main bearing bar spacing-span ratio, proposes the correction factor that can calculate the effective width ratio of the unfilled steel composite steel grid deck.

• Journal of The Korean Society of Agricultural Engineers
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• v.59 no.4
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• pp.43-52
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• 2017

This study analyzed pore water pressure, earth pressure and settlement through laboratory model tests in order to suggest the effective remodeling method in the case of reinforcing the upstream and downstream slope of deteriorated reservoirs that has no cores and filters or is not functional. The method of remodeling the upstream slope using dredge soil is first prevent seepage by installing the core, and the leakage water can be rapidly discharged through a filter installed on the downstream slope. Therefore, it is considered a highly efficient method of remodeling that reduces piping phenomena and increasing the storage capacity of the reservoir. The variation of earth pressure without the core and filter was greater than with it, while the change largely showed in the upstream slope, the downstream slope did not show any significant changes. The remodeling method of the downstream slope with the core appeared differently pore water pressure depending on the presence of the vertical and horizontal filters. In the upstream slope, the pore water pressure rises sharply, the base and middle gradually increased, and the downstream slope appeared small. The pore water pressure of embankment with a vertical and horizontal filter will be smaller than without it. The remodeling of deteriorated reservoir that does not have the function of the filter, the vertical filter must be installed in a position that is higher than the expected seepage line by removing portions of the downstream slopes. Since the horizontal filter is an important structure that provides stable drainage during an earthquake or concentrated leak, it is necessary to examine any change in the seepage characteristics depending on the filter intervals via three-dimensional finite element analysis, and it should be connected to the tow-drain to reduce the possibility of the collapse of the reservoir.

• Advances in concrete construction
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• v.5 no.2
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• pp.117-143
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• 2017

The attack of environmental aggressive agents progressively reduces the structural reliability of buildings and infrastructures and, in the worst exposition conditions, may even lead to their collapse in the long period. A change in the material and sectional characteristics of a structural element, due to the environmental damaging effects, changes its mechanical behaviour and varies both the internal stress redistribution and the kinematics through which it reaches its ultimate state. To identify such a behaviour, the evolution of both the damaging process and its mechanical consequences have to be taken into account. This paper presents a computational approach for the analysis of reinforced and prestressed concrete elements under sustained loading conditions and subjected to given damaging scenarios. The effects of the diffusion of aggressive agents, of the onset and development of the corrosion state in the reinforcement and the corresponding mechanical response are studied. As known, the corrosion on the reinforcing bars influences the damaging rate in the cracking pattern evolution; hence, the damage development and the mechanical behaviours are considered as coupled phenomena. The reliability of such an approach is validated in modelling the diffusion of the aggressive agents and the changes in the mechanical response of simple structural elements whose experimental behaviour is reported in Literature. A second set of analyses studies the effects of the corrosion of the tendons of a P.C. beam and explores potentially unexpected structural responses caused by corrosion under different aggressive exposition. The role of the different types and of the different positions of the damaging agents is discussed. In particular, it is shown how the collapse mode of the beam may switch from flexural to shear type, in case corrosion is caused by a localized chloride attack in the shear span.

• Journal of Korean Society of Steel Construction
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• v.27 no.2
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• pp.207-217
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• 2015

A concentrically braced steel frame is a very efficient structural system because it requires relatively smaller amount of materials to resist lateral forces. However, primarily developed as a structural system to resist wind loads based on an assumption that the structure behaves elastically, a concentrically braced frame possibly experiences the deterioration in energy dissipation after brace buckling and the brittle failure of braces and connections when earthquake loads cause inelastic behavior. Consequently, plastic deformation is concentrated in the floor where brace buckling occurs first, which can lead to the rupture of the structure. This study suggests reinforcing H-shaped braces with non-welded cold-formed stiffeners to restrain flexure and buckling and resist tensile force and compressive force equally.

• Structural Engineering and Mechanics
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• v.60 no.4
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• pp.567-594
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• 2016

The main objective of the current research is estimating the flexural behavior of ferrocement Ribbed Plates reinforced with composite material. Experimental investigation was carried out on fifteen plates; their dimensions were kept constant at 1200 mm in length, 600 mm width and 100 mm thick but with different volume fraction of steel reinforcement and number of ribs. Test specimens were tested until failure under three line loadings with simply supported conditions over a span of 1100 mm. Cracking patterns, tensile and compressive strains, deformation characteristics, ductility ratio, and energy absorption properties were observed and measured at all stages of loadings. Experimental results were compared to analytical models using ANSYS 10 program. Parametric study is presented to look at the variables that can mainly affect the mechanical behaviors of the model such as the change of plate length. The results showed that the ultimate strength, ductility ratio and energy absorption properties of the proposed ribbed plates are affected by the volume fraction and the type of reinforcement, and also proved the effectiveness of expanded metal mesh and woven steel mesh in reinforcing the ribbed ferrocement plates. In addition, the developed ribbed ferrocement plates have high strength, ductility ratio and energy absorption properties and are lighter in weight compared to the conventional RC ribbed plates, which could be useful for developed and developing countries alike. The Finite Element (FE) simulations gave good results comparing with the experimental results.

• Composites Research
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• v.13 no.6
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• pp.39-46
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• 2000

Electrical discharge machining (EDM) cuts metal by discharging electric current across a thin gap between tool and workpiece. Electrical discharge wire cutting, a special form of EDM, uses a continuously moving conductive wire as an electrode, and is widely used for the manufacture of punches, dies and stripper plates. In the wire cutting process, the moving wire is usually supported by cantilever arm and wire guides. As the wire traveling speed has been increased in recent years to improve productivity, the vibration of the cantilever arm occurs, which reduces the positional accuracy of the machine. Therefore, the design and manufacture of the cantilever arm with high dynamic characteristics have become important as the machining speed increases. In this paper, the cantilever arm for guiding the moving wire was designed and manufactured using carbon fiber epoxy composite in order to improve the static and dynamic characteristics. Specimens for the composite cantilever arm were manufactured and tested to investigate the effect of the number of reinforcing plies and length fitted to steel flange on the load capacity. Also, the finite element analysis using layer and contact elements was performed to compare the calculated results with the experimental ones. From the results, the prototype of the composite cantilever arm for the electrical discharge wire cutting machine was manufactured and the static and dynamic characteristics were compared with those of the conventional steel cantilever arm.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.32 no.6
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• pp.465-473
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• 2008

Type II compressed natural gas(CNG) storage vessels for automobiles have been acknowledged for their excellence and have recently become established in local regions. Their supply is not only to automakers in Korea such as Hyundai Motors but they are being increasingly exported. Although the available products have undergone safety evaluations and are certified by an authorized institution they are still short of the optimal design that is possible for such storage vessels. This research investigates the shape and thickness of the dome with the aim of optimizing the type II CNG storage vessels by using a finite element analysis technique. CNG storage vessels can be largely divided into 3 parts namely, the hear part, the cylinder part and the dome part. The head part is designed by means of a hot spinning process and this method is safer than that used in the design of the dome part even though its shape is similar. The thickness of the liners and reinforcing materials was optimized based on the requirements of the cylinder and dome parts. In addition, the shape of the dome, which is most suitable for Type II CNG storage vessels, is proposed by a process of review and analysis of various existing shape, and then conducting a structural stability evaluation to ensure the optimal design plan.

• The Journal of Internal Korean Medicine
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• v.23 no.1
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• pp.117-122
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• 2002

Objective : We conducted this study to analyze some of the trends of treatments from the recent Chinese medical journals and contribute them to the oriental medical experiments and clinical research for the future. Methods : By referring to the Chinese medical journals that were published in China from 1999 to March, 2002, we analyzed the effective rates on frequency, methods, medical treatment, and diseases. Result : The average effective rate was 90.93%, which was very high. Lately, there have been no big changes in the methods of treatment. The methods of coordinating stomach-Qi, supplying Yin element, replenishing bone marrow, tonifying essence of life, and removing blood stasis are used by means of reinforcing Qi, producing blood, tonilying spleen, and replenishing the kidney. Conclusions : The decreased in bone marrow and leucopenia, and the side effects of radiotherapy and chemotherapy were more effectively treated when we used Korean oriental medical treatments. In addition, more Korean oriental medical experiments and clinical studies are needed in Korea, in the future.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.09b
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• pp.152-160
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• 2010

In this study, cohesion of soft ground, soft ground depth and embankment height varying conditions, such as the impact of each condition after the calculation of the range, SCP was performed to evaluate the applicability of the method. Reinforcing effects of scope, and permit lateral movement of SCP 2D and 3D analysis of the program were calculated by the displacement ratio, the result follows. The height and depth of soft soil embankment with increasing and decreasing the cohesion tends to be affected were long range, SCP method applied by the finite element analysis Cu = 1.0tf/$m^2$, embankment height is 3.0m depth of soft soil can be applied in a less than 5.0m, and Cu = 3.0tf/$m^2$, embankment height, the soft soil depth is 3.0m 12.0m, Cu = 3.0tf/$m^2$, embankment height is 5.0m less than 7.0m depth of soft soil can be applied in was. And Cu = 5.0tf/$m^2$, embankment height is 3.0m below 15.0m depth rouge anti Floor, Cu = 3.0tf/$m^2$, embankment height of 5.0m 12.0m depth below the soft soil, Cu = 5.0tf/$m^2$, If the depth of soft soil embankment height of 7.0m and below 5.0m was applicable.

• Geomechanics and Engineering
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• v.14 no.4
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• pp.345-354
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• 2018

Currently, layered geogrid method (LGM) is the commonly practiced technique for reinforcement of slopes. In this paper the geogrid-box method (GBM) is introduced as a new approach for reinforcement of rock-soil slopes. To achieve the objectives of this study, a laboratory setup was designed and the slopes without reinforcements and reinforced with LGM and GBM were tested under the loading of a circular footing. The effect of vertical spacing between geogrid layers and box thickness on normalized bearing capacity and failure mechanism of slopes was investigated. A series of 3D finite element analysis were also performed using ABAQUS software to supplement the results of the model tests. The results indicated that the load-settlement behavior and the ultimate bearing capacity of footing can be significantly improved by the inclusion of reinforcing geogrid in the soil. It was found that for the slopes reinforced with GBM, the displacement contours are widely distributed in the rock-soil mass underneath the footing in greater width and depth than that in the reinforced slope with LGM, which in turn results in higher bearing capacity. It was also established that by reducing the thickness of geogrid-boxes, the distribution and depth of displacement contours increases and a longer failure surface is developed, which suggests the enhanced bearing capacity of the slope. Based on the studied designs, the ultimate bearing capacity of the GBM-reinforced slope was found to be 11.16% higher than that of the slope reinforced with LGM. The results also indicated that, reinforcement of rock-soil slopes using GBM causes an improvement in the ultimate bearing capacity as high as 24.8 times more than that of the unreinforced slope.