• Journal of the Korean Magnetics Society
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• v.18 no.1
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• pp.36-38
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• 2008

We calculate the electron scattering amplitude with reduced angular momentum expansion(RAME) and compare it with the plane wave approximation. By using WKB approximation it is shown that the curvature correction factor given by RAME is originated from the source wave centrifugal potential energy. The factor also can be understood as an effective wave number correction factor in plane wave approximation. Angular momentum and its relationship with scattering amplitude is explicitly shown.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2000.04a
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• pp.259-266
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• 2000

This study was conducted to investigate the seismic behavior assessment of circular reinforcement concrete bridge piers particularly with regard to assessing the displacement ductility curvature ductility response modification factor(R) and plastic hinge region etc, The experimental variables of bridge piers test consisted of transverse steel details amount and spacing different axial load levels etc. The test results indicated that reinforcement concrete bridge piers with confinement steel by the code specification exhibited suffcient ductile behavior and seismic performance. Also it is found that current seismic design code specification of confinement steel requirements may be revised.

• Communications of the Korean Mathematical Society
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• v.10 no.2
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• pp.365-374
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• 1995

On a compact manifold without conjugate points, the volume entropy can be obtained as the average mean curvature of the horospheres in the universal covering space. In the case when the volume entropy is zero, we prove that the universal covering space is diffeomorphic to a product space with a line factor. This fact can be considered as a surporting evidence for the Mane's conjecture, which claims the flatness of the mainfold.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.5
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• pp.346-356
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• 2018

Overweight and abdominal obesity caused by sedentary lifestyle may induce deconditioned and atrophied extensor musculature of the lumbar spine and be a potential risk factor for low back pain (LBP). Therefore, this study was conducted to evaluate the validity of high intensity circuit training (HICT) on weight loss and subsequent alleviation of spine curvature (SC) and visual analog scale (VAS) among middle aged men with abdominal obesity. The training program (1 exercise session for 30 minutes, three times a week for 12 weeks) consisted of 12 different functional exercises based on core strengthening multiple joint circuit training. Portions of the obesity index related to body composition were positively changed, which improved the angles of thoracic kyposis and lumbar lordosis, which appeared to effectively reduce lower back pain. Taken together, HICT specifically designed for LBP effectively decreased obesity related body composition and was superior to other treatments for decreasing aggravation of the spine curvature and LBP caused by abdominal obesity; however, weight loss should be the primary treatment target for LBP patients.

• Journal of Korean Medicine Rehabilitation
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• v.33 no.4
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• pp.185-193
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• 2023

Objectives This study was conducted to find out the correlation between lumbar malposition and lumbar disc herniation. Methods Among the patients who visited Gwangju Jaseng Hospital of Korean Medicine from January 2019 to January 2021, taking 92 patients under age 60 who had the records of X-rays and magnetic resonance imaging (MRI) images as the research subjects, Cobb's angle was measured in anterior-posterior (AP) view and lateral (LAT) view, the number of displacements was scored by listing categories defined by The Korean Society of Chuna Manual Medicine for Spine and Nerves. The degree of lumbar intervertebral disc herniation was expressed as a percentage according to the method of Kato, etc., and the correlation between each factor was analyzed. Results AP curvature and MRI herniation index showed significant positive correlation in L4-L5 level but there was no significant difference in L5-S1 level. LAT curvature and MRI herniation index had no correlation in L4-L5 level, but there was a significant negative correlation in L5-S1 level. Malposition score and MRI herniation index had a significant positive correlation in L5-S1 level, whereas there was no correlation in L4-L5. Conclusions As a result of the study, AP curvature and MRI herniation index showed a significant positive tendency in L4-L5 lumbar spine, and LAT curvature and MRI herniation index showed a significant negative tendency in L5-S1 lumbar spine. Malposition score and MRI herniation index were found to have a significant positive tendency in L5-S1 lumbar spine.

• Journal of Korean Society of Steel Construction
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• v.14 no.6
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• pp.803-811
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• 2002

Current composite steel and concrete bridges are designed using full-interaction theory assuming there is no relative slip, between the steel and concrete components along their interface, because of the complexities of partial-interaction analysis techniques. However, in the assessment of existing composite bridges this simplification may not be warranted as it is often necesary to extract the correct capacity and endurance from the structure. This may only be achieved using partial-interaction theory which tuly reflects the behaviour of the structure. In this paper, Parametric analyses have been carried out in order to confirm the partial-interaction curvatures with deflection effect using the finite element method. Therefore, the model is considered for simply supported steel and concrete composite bridges with a uniform distribution of connectors subjected to a single concentrated load. For the case studies, this study applicate a parameters such as the number and space of stud shear connector and elastic modulus of concrete slabs. From this study, it is known that partial-interaction effect was in the increase to the increasing the deflection of composite bridges, and stiffness and strength of slab concrete considering the occurrence of crack effect seriously to the partial-interaction behavior.

• Journal of the Korean Recycled Construction Resources Institute
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• v.9 no.2
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• pp.143-151
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• 2021

Flexural test of reinforced concrete beam with corroded reinforcement were performed to measure the deflection, curvature and cracking moment for various bar diameter and amounts of corrosion. The amounts of corrosion are varied from 0% to 10% by weight and the bar diameters are chosen as 10mm, 13mm, and 19mm. The changes in reinforcement diameter do not affect the flexural behaviors significantly according to this experiment. If the amounts of corrosion is greater than 2%, the deflection and curvature of the beam increased and the cracking moment decreased. It means that the lower amounts of corrosion does not result structural damage in flexural member significantly as in direct tensile test. A modification factor considering an effect of amounts of corrosion is proposed based on the experiment, which can be used to determine the deflection of reinforced concrete beam with corroded reinforcement.

• Restorative Dentistry and Endodontics
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• v.46 no.1
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• pp.5.1-5.13
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• 2021

Objectives: The aim of the current study was to assess whether the amount of extruded debris differs for straight and severely curved root canals during retreatment using H-files, R-Endo, Reciproc and ProTaper Universal Retreatment (PTU-R) files. Additionally, the area of residual filling material was evaluated. Materials and Methods: Severely curved (n = 104) and straight (n = 104) root canals of maxillary molar teeth were prepared with WaveOne Primary file and obturated with gutta-percha and AH Plus sealer. Root canal filling materials were removed with one of the preparation techniques: group 1: H-file; group 2: R-Endo; group 3: Reciproc; group 4: PTU-R (n = 26). The amount of extruded material and the area of the residual filling material was measured. The data were analyzed with 2-way analysis of variance (ANOVA) and 1-way ANOVA at the 0.05 significance level. Results: Except for Reciproc group (p > 0.05), PTU-R, R-Endo, and H-file systems extruded significantly more debris in severely curved canals (p < 0.05). Each file system caused more residual filling material in severely curved canals than in straight ones (p < 0.05). Conclusions: All instruments used in this study caused apical debris extrusion. Root canal curvature had an effect on extruded debris, except for Reciproc system. Clinicians should be aware that the difficult morphology of the severely curved root canals is a factor increasing the amount of extruded debris during the retreatment procedure.

• Steel and Composite Structures
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• v.37 no.3
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• pp.371-390
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• 2020

One of the most common strategies for retrofitting as-built reinforced concrete (RC) columns is to enlarge the existing section through the application of a new concrete layer reinforced by both steel transverse and longitudinal reinforcements. The present study was dedicated to developing a comprehensive model to predict the seismic behavior of as-built RC jacketed columns. For this purpose, a new sectional model was developed to perform moment-curvature analysis coupled by the plastic hinge method. In this analysis-oriented model, new methodologies were suggested to address the impacts of axial, flexural and shear mechanisms, variable confining pressure, eccentric loading, longitudinal bar buckling, and varying axial load. To consider the effective interaction between core and jacket, the monolithic factor approach was adopted to extent the response of the monolithic columns to that of a respective RC jacket strengthened column. Next, parametric studies were implemented to examine the effectiveness of the main parameters of the RC jacket strategy in retrofitting as-built RC columns. Ultimately, the reliability of the developed analytical model was validated against a series of experimental results of as-built and retrofitted RC columns.

• Korean Journal of Applied Biomechanics
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• v.20 no.3
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• pp.319-325
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• 2010

The purpose of this research was to investigate the differences in the ski carving turn motion according to level of expertise. The posture and movement of 6 skiers nearby the fall-line was evaluated with a biomechanical approach focusing the rotational mechanics. The slope was at an angle of $9^{\circ}$ and the following variables were measured and calculated: tangential velocity, change of COM height after passing fall-line, width between feet, angle between upper body and thigh, trunk angle, average radius of curvature and average centripetal force. The expert skiers minimized their center of mass height movement and maintained the width of between their feet after the passing the fall-line in comparison with the beginners and intermediate skiers. The experts restrained themselves from pushing their upper body downward after the turn to maximize the centripetal force. The experts in comparison with the beginners and intermediate skiers during the turn didn't have to reduce their radius of curvature to maintain a high centripetal force. It was concluded, that the most important factor affecting the centripetal force, was for the beginners and intermediate skiers, to minimize their movement while using the appropriate amount of edging.