• Computers and Concrete
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• v.12 no.2
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• pp.131-149
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• 2013

Various types of reinforcement splicing methods have been developed and implemented in reinforced concrete construction projects for achieving the continuity of reinforcements. Due to the complicated reinforcement arrangements and the difficulties in securing bar spacing, the traditional lap splicing method, which has been widely used in reinforced concrete constructions, often shows low constructability and difficulties in quality control. Also, lap spliced regions are likely to be over-reinforced, which may not be desirable in seismic design. On the other hand, mechanical splicing methods can offer simple and clear arrangements of reinforcement. In order to utilize the couplers for the ribbed-deformed bars, however, additional screw processing at the ends of reinforcing bars is typically required, which often lead to performance degradations of reinforced concrete members due to the lack of workmanship in screw processing or in adjusting the length of reinforcing bars. On the contrary, the use of screw-ribbed reinforcements can easily solve these issues on the mechanical splicing methods, because it does not require the screw process on the bar. In this study, the mechanical coupler suitable for the screw-ribbed reinforcements has been developed, in which any gap between the reinforcements and sleeve device can be removed by grouting high-flow inorganic mortar. This study presents the uniaxial tension tests on the screw-ribbed reinforcement with the mechanical sleeve devices and the cyclic loading tests on RC columns with the developed coupler. The test results show that the mechanical sleeve connection developed in this study has an excellent splicing performance, and that it is applicable to reinforced concrete columns with a proper confinement by hoop reinforcement.

• Journal of KIISE:Computing Practices and Letters
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• v.12 no.3
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• pp.208-217
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• 2006

This paper presents a cloth simulation technique that implements plastic deformation. Plasticity is the property that material does not restore completely to the original state once deformed, in contrast to elasticity. We model cloth using a particle model, and posit two kinds of connections between particles, i.e. the sequential connections between immediate neighbors, and the interlaced connections between every other neighbors. The sequential connections represent the compression and tension of cloth, and the interlaced connections the bending in cloth. The sequential connections are modeled by elastic springs, and the interlaced connections by elastic or plastic spring depending on the amount of the current deformation of the connections. Our model is obtained by adding plastic springs to the existing elastic particle model of cloth. Using the new model, we have been able to simulate bending wrinkles, permanently deformed wrinkles, and small wrinkles widely distributed over cloth. When constructing elastic and plastic spring models for sequential and interlaced connections, we took pain to prevent the stiffness matrix of the whole cloth system from being indefinite, in order to help achieve physical stability of the cloth motion equation and to improve the effectiveness of the numerical method.

• Magazine of the Korea Concrete Institute
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• v.8 no.3
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• pp.187-195
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• 1996

A finite element formulation based on the CFT(Compression Field Theory), considering the effect of compression softening in cracked concrete, and macro-scopic and rotating crack models etc., was presented for the nonlinear behaviour of structural concrete. Considering the computational efficency and the ability of modelling the post-ultimate behaviour as major concerns, the Incremental displacement solution algorithm involving initial material stiffnesses and the relaxation procedure for fast convergence was adopted and formulated in a type of 8-noded quadrilateral isoparametric elements. The analysis program NASCOM(Non1inear Analysis of Structural Concrete by FEM : Monotonic Loading) developed in this way enables the predictions of strength and deformation capacities in a full range, crack patterns and their corresponding widths, and yield extents of reinforcement. As the verification purpose of NASCOM, the predictions were made for Bhide's Panel(PB21) and Leonhardt's deep beam tests. The predicted results shows somewhat stiff behaviour for the panel test, and vice versa for deep beam tests. More refining process would be necessary hereafter in terms of more accurately simulating the effects of tension-stiffening and compression softening in concrete.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.8 no.2
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• pp.125-133
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• 1988

To establish the rational design method, it is very important that predict accurately load-deformation response on reinforced concrete members. Torque-twist curves of reinforced concrete members in pure torsion were proposed recently by Collins and Hsu, etc. But, it is found that torsional strength of reinforced concrete members based on Hsu's theory is underestimated in the over-all load region except the ultimate state. In this paper, an attempt is made to present the higher-precision of torsional strength on arbitrary loading condition. For this purpose, constitutive equations are derived from which an estimate can be made of the torsional behavior of reinforced concrete members under the pure torsion. Tension stiffness of concrete in both the cracked and uncracked state have been considered. A softening effect that reduces the strength of the concrete by the diagonal cracking of concrete have been appropriately deliberated. Particularly, the experiments was done with 14 test beams to investigate the validity of theoretical analysis.

• Journal of the Korean Recycled Construction Resources Institute
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• v.4 no.2
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• pp.112-117
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• 2016

This research compared the tensile performance of the vegetation mat, which was developed byu using the rapidly growing biodegradable plastic, Poly Lactic Acid(PLA), according to the biodegradation period. The test applied the method defined by Korean Standard KS. In the result of experiment using single-material PLA mesh and PLA plastic, the tensile strength and molecular weight were inverse-proportional to the 5 months of biodegradation period. The thickness of PLA mesh was increased by 11.2~13.4% while the tensile strenth of it was reduced by 32.4~55.4%. The tensile strength and molecular weight of PLA plastic were also reduced over time. However, the tension test of vegetation mat comprised of PLA mesh, non-woven fabric (including seeds), and jute net didn't have specific tendency.

• Advances in biomechanics and applications
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• v.1 no.2
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• pp.127-141
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• 2014

A preliminary study of a new pulsatile pump that will work to a frequency greater than 1 Hz, is presented. The fluid-structure interaction between a Newtonian blood flow and a piston drive that moves with periodic speed is simulated. The mechanism is of double effect and has four valves, two at the input flow and two at the output flow; the valves are simulated with specified velocity of closing and reopening. The simulation is made with finite elements software named COMSOL Multiphysics 3.3 to resolve the flow in a preliminary planar configuration. The geometry is 2D to determine areas of high speeds and high shear stresses that can cause hemolysis and platelet aggregation. The opening and closing valves are modelled by solid structure interacting with flow, the rhythmic opening and closing are synchronized with the piston harmonic movement. The boundary conditions at the input and output areas are only normal traction with reference pressure. On the other hand, the fluid structure interactions are manifested due to the non-slip boundary conditions over the piston moving surfaces, moving valve contours and fix pump walls. The non-physiologic frequency pulsatile pump, from the viewpoint of fluid flow analysis, is predicted feasible and with characteristic of low hemolysis and low thrombogenesis, because the stress tension and resident time are smaller than the limit and the vortices are destroyed for the periodic flow.

• Clinics in Shoulder and Elbow
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• v.10 no.2
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• pp.155-159
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• 2007

Arthroscopic single-row rotator cuff repair is a well established surgical technique for the treatment of rotator cuff tears. However, the problem of postoperative retear remains a concern. Various avenues are being explored to address this problem. Some studies have suggested that restoring the anatomical footprint may improve the healing and initial strength of the repaired rotator cuff tendon. The double-row technique was introduced as a method of reconstructing the anatomical footprint. According to biomechanical studies on cadavers, this technique improved mechanical strength and reduced gap formation. However, the biological properties of reattached tendon such as tension, and vascularity have not been proved yet. Furthermore, the apparent mechanical superiority of the double-row over the single-row construction has not resulted in better functional outcomes. Therefore, the less complicated and less costly single-row technique is still the recommended treatment for rotator cuff repairs.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.1
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• pp.70-78
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• 2009

Floodplain areas of major South Korean rivers were determined by analyzing topographical maps and hydraulic properties of floodplain soil were measured using disc tension infiltrometer. To assess the possibility of treating secondary effluents of municipal wastewater with floodplain soil, a computer code for the analysis of unsaturated flow in soil was employed along with searches conducted in the literature. Based on the data generated, an estimate of total floodplain filtration capacity in Korea was obtained. The results of our study reveal that Korean floodplains have surface soil that is adequate for treating water. Moreover, the distributions of floodplains are substantial over the entire reaches of the rivers, indicating that the conditions are favorable for floodplain filtration as additional treatment of secondary effluent. The capacity of floodplain filtration in Korea is circa 182,000,000 $m^3$/day and most of the rivers are estimated to have enough capacity of floodplain filtration to meet all the secondary effluent, indicating that this technology may be expected to make further improvements on river water quality. Furthermore, this method may also be applied to better the source-water quality for drinking water.

• Archives of Reconstructive Microsurgery
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• v.7 no.1
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• pp.68-72
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• 1998

With the advent of microvascular free-tissue transfer, this single stage resurfacing method for large scar and soft tissue defects around the wrist in the patients of electrical burn has distinctive advantage over the conventional multistage pedicle-flap transfer. Between 1992 and 1996, we treated 9 cases of 8 patients who had large scar around the wrist due to old electrical burn with free flaps as a preparation of staged tendon graft. Mean age was 30.3 years and average scar area was $6{\times}11cm$. The length of time the injury and free flaps was 9 months on an average. Prior to the free flap, we performed the angiography to all patients in order to evaluate the circulation of the forearm and hand and to choose the recipient vessel. In all cases, proximal ulnar arteries in the forearm remained intact and all radial arteries remained intact in 8 of 9 cases on angiogram. The interosseous arteries were well visualized in all cases. We used the ulnar arteries as a recipient artery. The types of flaps used were f scapular cutaneous flaps, 2 dorsalis pedis flaps and a radial forearm flap. Flap survial was 100 percents with satisfactory functional and cosmetic results. Free flaps using ulnar artery as a recipient artery is one of the useful reconstruction methods for the resurfacing of large scar around the wrist in the patients of old electrical burn.

• Journal of Korean Academy of Nursing
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• v.53 no.5
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• pp.538-555
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• 2023

Purpose: This qualitative study used interpretative phenomenological analysis and photovoice methods to explore the meaning of non-suicidal self-injury experienced by adolescents. Methods: Participants were adolescents enrolled in middle and high schools in Gyeonggi-do and Jeollabuk-do who were selected through snowball sampling. Six participants had repeatedly engaged in self-injurious behavior for over a year. Data were collected through in-depth interviews and the photovoice method between November 2020 and July 2021. The collected data were analyzed using six steps of interpretative phenomenological analysis. Results: The results yielded 5 main themes and 18 subthemes. The main themes were 'a silent cry to an indifferent world', 'a heartache that one endures with scars', 'an inescapable cycle', 'filling the space in one's heart', and 'healing the wounds'. The study findings revealed that the self-injurious behavior of adolescents began as a consequence of feeling lost and struggling with conflicts at home and school, which helped them relieve tension and pain. Nonetheless, inflicting self-injury only left signs of regret and remorse, which became a trace that the participants wanted to hide. However, the wounds healed after receiving attention and support from others. They were determined to stop engaging in repeated self-injurious behaviors and made efforts to do so. Conclusion: This study can be used as a basis for the development of educational programs to prevent non-suicidal self-injury in adolescents. Additionally, it can inform nursing interventions that focus on building support systems to help adolescents who attempt self-injury.