• Smart Structures and Systems
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• v.19 no.4
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• pp.371-382
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• 2017

Concrete filled steel tubes are extensively applied in engineering structures due to their resistance to high tensile and compressive load and convenience in construction. But one major flaw, their vulnerability to environmental attack, can severely reduce the strength and life of these structures. Degradation due to corrosion of steel confining the concrete is one of the major durability problems faced by civil engineers to maintain these structures. The problem accelerates as inner surface of steel tube is in contact with concrete which serves as electrolyte. If it remains unnoticed, it further accelerates and can be catastrophic. This paper discusses a non-destructive degradation monitoring technique for early detection corrosion in steel tubes in CFST members. Due to corrosion, damage in the form of debonding and pitting occurs in steel sections. Guided ultrasonic waves have been used as a feasible and attractive solution for the detection and monitoring of corrosion damages in CFST sections. Guided waves have been utilized to monitor the effect of notch and debond defects in concrete filled steel tubes simulating pitting and delamination of steel tubes from surrounding concrete caused by corrosion. Pulse transmission has been used to monitor the healthy and simulated damaged specimens. A methodology is developed and successfully applied for the monitoring of concrete filled steel tubular sections undergoing accelerated chloride corrosion. The ultrasonic signals efficiently narrate the state of steel tube undergoing corrosion.

• BMB Reports
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• v.42 no.5
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• pp.304-309
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• 2009

Nanoparticulate platinum (II) (nano Pt) is a powerful antioxidant that is widely used to scavenge reactive oxygen species (ROS). The antioxidant activity of nano Pt has gained attention as a potentially useful therapeutic for a variety of diseases including cancer and aging. In the present study, we prepared nanoparticulate saponin-Pt (II) (nano saponin-Pt) conjugates using the ethanol reduction method to enhance the permeability and retention effect of Pt. The nano saponin-Pt conjugates were found to restore the viability of approximately 40% of 2,4-dinitrofluorobenzene (DNFB)-treated RAW 264.7 cells. In addition, we found that nano saponin-Pt conjugates acted as a potent antioxidant that reduced the production of ROS and inhibited activation of the MAP kinase pathway and MIP-2 gene expression in response to DNFB. These results provide insight into the potential usefulness of nano saponin-Pt conjugates as a treatment for contact hypersensitivity.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.29 no.9 s.240
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• pp.1175-1182
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• 2005

General systems have many substructures assembled at joints. The bolted joint is generally used in assembling the mechanical parts. However, there are no effective modeling methods to analyze the dynamic characteristics of bolt jointed structure using the finite element (FE) analysis, especially in case of large area contact. Moreover, the design methods for the appropriate bolt locations and the number of bolts considering the dynamic characteristics are not guided properly. In this study, a proper modeling method is developed to simulate the dynamic characteristics of a structure with the large interfaced area using the cone frusta method and spring elements. The natural frequencies are also controlled by adjusting the bolt-joint location and the number of bolts considering relative distances in mode shapes at the interface of bolt-jointed plates. The Modeling method and the optimized design method are verified based on the experimental and the FE analysis results.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.8 no.6
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• pp.84-91
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• 1999

The goal of this study is to analyse the stress and the strain occurring within the work piece at the fine-blanking process and hence to assume the size direction and a distribution chart of the shearing stress as the penetration of the punch is being increased trough the application of the FEM. For this analysis we introduced the piece-wise linear method in the non linear structural analysis program for large deformation sheet metal forming and we defined it as the problem of the non linear contact. Therefore we modeled the above problems as quadratic-nodded axi-symmetrical elements for the character-istics of the work piece. From the result of this analysis it was found that the shearing stress is a great deal occurred on the surface of the work piece during the beginning process of the punch penetration and it's effect is expected to influence importantly for the formation of burnish because the deeper is the penetration of the punch in the narrow clearance zone. the greater is the degree of the strain stress.

• Geomechanics and Engineering
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• v.16 no.3
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• pp.309-320
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• 2018

In this paper, a numerical study using finite element method with considering soil-structure interaction was conducted to investigate the stress and deformation behavior of a sheet pile wall structure. In numerical model, one of the nonlinear elastic material constitutive models, Duncan-Chang E-v model, is used for describing soil behavior. The hard contact constitutive model is used for simulating the behavior of interface between the sheet pile wall and soil. The construction process of excavation and backfill is simulated by the way of step loading. We also compare the present numerical method with the in-situ test results for verifying the numerical methods. The numerical analysis showed that the soil excavation in the lock chamber has a huge effect on the wall deflection and stress, pile deflection, and anchor force. With the increase of distance between anchored bars, the maximum wall deflection and anchor force increase, while the maximum wall stress decreases. At a low elevation of anchored bar, the maximum wall bending moment decreases, but the maximum wall deflection, pile deflection, and anchor force both increase. The construction procedure with first excavation and then backfill is quite favorable for decreasing pile deflection, wall deflection and stress, and anchor forces.

• Geomechanics and Engineering
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• v.20 no.5
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• pp.433-445
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• 2020

A new code, called PRaFULL (Piled Raft Foundation Under Lateral Load), was developed for the analysis of laterally loaded Combined Pile Raft Foundation (CPRF). The proposed code considers the contribution offered by the raft-soil contact and the interactions between all the CPRF system components. The nonlinear behaviour of the reinforced concrete pile and the soil are accounted. As shallower soil layers are of great relevance in the lateral response of a pile foundation, PRaFULL includes the possibility to consider layered soil profiles with appropriate properties. The shadowing effect on the ultimate soil pressure is accounted, when dealing with pile groups, as proposed by the Strain Wedge Model. PRaFULL BEM code obviously requires less computational resources compared to FEM (Finite Element Method) or FDM (Finite Difference Method) codes. The proposed code was validated in the linear elastic range by comparisons with the code APRAF (Analysis of Piled Raft Foundations). The reliability of the procedure to predict piled raft performance was then verified in nonlinear range by comparisons with both centrifuge tests and computer code PRAB.

• Fisheries and Aquatic Sciences
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• v.13 no.2
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• pp.182-189
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• 2010

An active stimulating device (ASD) using a rope apparatus may operated by the flow of turbulence inside a cod end, generating variable stimuli in addition to flow-related effects to minimize the by-catch of juvenile fishes. Preliminary testing involved a hydrodynamic effect inside the cod end with a rotating rope kite or conical rope array to generate variable stimuli (visual stimuli, water flow, or physical contact with fish) to change fish position. The experimental rope kite offered more choice in rotating period and range of sweeping action; adjusting the towing line or flow velocity helped to drive fish toward the net panel and encouraged escape. The conical shape of the rope array in the cod end helped to clear a path for fish by disturbing the rigging and providing more contrast between objects, preventing an optomotor response. This enabled more black porgy to be herded toward the net at an early stage of towing. Therefore, either a conical rope array or a rotating rope kite can be used as an effective ASD to prevent juvenile by-catch.

• Korean Journal of Adult Nursing
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• v.21 no.4
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• pp.435-445
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• 2009

Purpose: This study was to examine whether VRE infection control strategies have an effect on the decrease in incidence rates for VRE acquisition and VRE nosocomial infection in ICU. Methods: All the patients were examined for VRE carriers on ICU admission. Among them, patients hospitalized for over 48 hours were investigated for VRE acquisition rates and VRE nosocomial infection rate using VRE infection control strategies in ICU for the experimental group from September 2007 to April 2008. Before that, incidence of VRE acquisition and VRE nosocomial infection for the control group without Intervention were investigated from May to August 2007 retrospectively. Results: VRE acquisition rate in clinical specimens was 0.6% in the experimental group, that was significantly lower when compared to the control group. VRE carrier rate at admission to ICU was 15.4%. Out of 182 VRE carriers, 180 patients were identified by the active surveillance culture. Conclusion: These results suggested that active surveillance culture at admission was considered to be an essential measure for detection of VRE carrier. But without strict isolation and adherence rating after each intervention, hand washing and contact isolation alone did not significantly decrease VRE nosocomial infection, although it did significantly decrease incidence of VRE acquired from clinical specimen.

• IMMUNE NETWORK
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• v.8 no.2
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• pp.46-52
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• 2008

Background: Oral tolerance is defined by the inhibition of immune responsiveness to a protein previously exposed via the oral route. Protein antigens exposed via the oral route can be absorbed through the mucosal surfaces of the gastrointestinal tract and can make physical contact with immune cells residing in the intestinal lamina propria (LP). However, the mechanisms of oral tolerance and immune regulation in the intestines currently remain to be clearly elucidated. Methods: In order to determine the effect of oral protein antigen intake (ovalbumin, OVA) on the intestinal LP, we assessed the expression profile of the T cell receptor and the co-receptors on the cells from the intestines of the tolerant and immune mouse groups. Results: We determined that the proportion of OVA-specific B cells and ${\gamma}{\delta}$ T cells had decreased, but the CD8${\alpha}{\beta}$ and D8${\alpha}{\alpha}$ T cells were increased in the LP from the tolerant group. The proportion of CD8＋ T cells in the spleen did not evidence any significant differences between treatment groups. Conclusion: These results indicate that CD8＋ T cells in the intestinal LP may perform a regulatory role following antigen challenge via the oral route.

• Journal of Korean Clinical Health Science
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• v.5 no.4
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• pp.1021-1025
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• 2017

Purpose: Changes in corneal thickness after wearing hydrogel lens and silicone-hydrogel lens with different oxygen transmission rates wew syudied. Methods: Experiments were performed on 11 subjects(22 eyes). corneal thickness was measured after wearing contact lenses for 8 hours. Corneal thickness was measured using ORB Scan II(ver. 3.14) Results: In the results of the corneal thickness measurement by direction, in the case of the hydrogel-tor lens, the center thickness was $33.63{\mu}m$, the nasal was $34.29{\mu}m$, the temporal was $27.17{\mu}m$, the inferior was $27.17{\mu}m$, the superior was $18.90{\mu}m$, and change rates were 6.28%, 5.71%, 5.40%, 4.75% and 3.09%, respectively. In the results of the corneal thickness measurement by diameter, in the case of the hydrogel-tor lens, the center was $33.63{\mu}m$, the mid-peripheral was $28.19{\mu}m$, the peripheral was $24.18{\mu}m$, and change rates were 6.28%, 4.76%, and 3.79%, respectively. Conclusions: The hydrogel lenses with relatively low oxygen transmission rates resulted in a significant increase in thickness over the entire cornea compared to silicon-hydrogel lenses with high oxygen transmission rates.