• Proceedings of the KSME Conference
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• 2001.06b
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• pp.601-606
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• 2001

Free vibration analysis was performed for a spinning disk/spindle system mounted on a flexible baseplate. A simplified model was presented considering the effects of the baseplate flexibility on a disk/spindle system, and the equations of motion were derived by the assumed mode method and Lagrange's equation. From the results of the tree vibration analysis, the variations of the natural frequencies were investigated by changing rotating speed, baseplate thickness. They were attributed to the coupling between the flexible modes of the spinning disk/spindle system and the baseplate. This simplified model was used to predict the dynamic characteristics of a small size disk drive. The validity of the simplified model was verified by experiments and FE analysis.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.27 no.1
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• pp.21-30
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• 2021

Background: This study aimed to investigate the effects of muscle energy technique (MET) and instrument assisted soft tissue mobilization (IASTM) on knee extension ROM, knee extensor/flexor strength and muscle thickness immediately and after 24 hours. Methods: A total of 30 subjects participated in this study. The participants were assigned to either MET (n=15) or IASTM (n=15). 90-90 straight leg raise, knee extensor/flexor muscle strength, muscle thickness test were measured before, immediately after and 24 hours after the intervention. Results: Both groups significantly improved knee extension ROM on immediate (MET 10.7°, IASTM 10.21° increased) and after 24 hours assessment (MET 5.61°, IASTM 5.47° increased)(p<.05). In the MET group, knee extension and flexion muscle strength increased immediately after intervention (p<.05). In the IASTM group, knee extension muscle strength increased and knee flexor muscle strength decreased immediately after intervention (p<.05). Furthermore, both groups showed a pattern of returning to the initial strength after 24 hours. In both groups, no significant difference in muscle thickness immediately and after 24 hours was observed (p>.05). Conclusion: According to the results of the present study, MET and IASTM technique showed lasting effectiveness in flexibility of shortened hamstring immediately after and in 24 hours after the intervention. In both groups, MET increased muscle strength and increased ROM, while IASTM decreased muscle strength and increased ROM, with no change in muscle thickness.

• International Journal of Human Ecology
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• v.13 no.1
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• pp.105-115
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• 2012

This research investigated the influences of structural characteristics such as fabrics, mechanical properties, and subjective sensory images on the off-line and on-line preferences to women's spring/summer suits fabrics to extract the most effective factor towards preference as well as analyze the preferential off-line and on-line differences to predict the exact texture image on-line. Objective evaluations were done for the measurement of the mechanical properties of fabrics using Kawabata's Evaluation System and subjective evaluations were done with 109 female subjects who value the off-line and on-line sensory image of suit fabrics. For statistical analysis, factor analysis, cluster analysis, t-test, ANOVA, and regression were used. The results were as follows. The preference scores on-line were generally higher than those off-line. For the structural characteristics of fabrics, differences of thickness were observed according to preference clusters, and the preference increased as thickness was lowered off-line and on-line. For mechanical properties, WC influenced off-line and on-line preferences. Fabrics with low compression energy were preferred; however, the effect of SMD was observed off-line only. In subjective sensory images, the 'smoothness' image influenced off-line and on-line preferences the most. All sensory images influenced the off-line preferences; however, the effects of 'flexibility' and 'weight' were not shown on-line.

• Steel and Composite Structures
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• v.23 no.1
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• pp.1-16
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• 2017

This paper is presented to solve the buckling problem of functionally graded truncated conical shells subjected to displacement-dependent pressure which remains normal to the shell middle surface throughout the deformation process by the semi-analytical finite strip method. Material properties are assumed to be temperature dependent, and varied continuously in the thickness direction according to a simple power law distribution in terms of the volume fraction of a ceramic and metal. The governing equations are derived based on first-order shear deformation theory which accounts for through thickness shear flexibility with Sanders-type of kinematic nonlinearity. The element linear and geometric stiffness matrices are obtained using virtual work expression for functionally graded materials. The load stiffness also called pressure stiffness matrix which accounts for variation of load direction is derived for each strip and after assembling, global load stiffness matrix of the shell which may be un-symmetric is formed. The un-symmetric parts which are due to load non-uniformity and unconstrained boundaries have been separated. A detailed parametric study is carried out to quantify the effects of power-law index of functional graded material and shell geometry variations on the difference between follower and non-follower lateral buckling pressures. The results indicate that considering pressure stiffness which arises from follower action of pressure causes considerable reduction in estimating buckling pressure.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.31 no.1
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• pp.39-45
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• 1999

Refining in papermaking plays an important role in changing fiber properties as well as paper properties. The major effects of refining on pulp fibers are internal and external fibrillation, fiber shortening, and fines formation. Many workers showed that internal fibrillation of the primary refining effects was most influential in improving paper properties. In particular, refining produces separation of fiber walls into several lamellae, thus causing fiber wall swelling with water penetration. This leads to the increase of fiber flexibility and of fiber-to-fiber contact during drying. If the fibers are very flexible, they will be drawn into close contact with each other by the force of surface tension as the water is removed during the drainage process and drying stages. In order to study the effect of fiber wall delamination on paper properties, cross-sectional image of fibers in a natural condition had to be generated without distortion. Finally, it was well recognized that confocal laser scanning microscope (CLSM) could be one of the most efficient tool for creating and quantifying fiber wall delamination in combination with image analysis technique. In this study, the CLSM could be used not only to observe morphological features of transverse views of swollen fibers refined under low and high intensity, but also to investigate the sequence of fiber wall delamination and fiber wall breakage. From the CLSM images, increasing the specific energy or refining decreased the degree of fiber collapse, fiber cross-sectional area, fiber wall thickness and lumen area. High intensity refining produced more external fibrillation.

• Journal of the Korean Society of Clothing and Textiles
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• v.13 no.1 s.29
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• pp.79-87
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• 1989

In the part 1 and 2, relations were found between fundmental mechanical properties and primary hand values, performance of Korean women's summer and fall & winter fabrics. In this paper, in order to investigate the hand values and mechanical properties such as tensile, shearing, bending, compression, surface and thickness & weight of the core-spun yarn woven fabrics for Korean folk clothes were measured by KES-F system. The experimental results are statistically analyzed in the aspects of the mechanical properties, their effects on the hand values, formation of weared clothes and transformation behavior. The correlation in the hand values are analyzed, too. Furthermore, there mechanical properties are discussed in comparison with those values for kimono fabrics. The main results are summarized as follows: 1. The core-spun yarn woven fabrics for Korean folk clothes have box-shaped silhouette based on higher bending rigidity and shear elasticity. 2. The core-spun yarn woven fabrics for Korean folk clothes are inferior to silk fabrics, superior to polyester fabrics in formation. 3. A drapability and wrinkle recovery of core-spun yarn woven fabrics for Korean folk clothes formation for weared clothes are inferior to polyester fabrics, superior to silk fabrics. 4. A primary factor of mechanical properties contribute to the hand values of core-spun yarn woven fabrics for Korean folk clothes are same as the Korean women's winter fabrics, except for flexibility with soft feeling. 5. As for the hand values of core-spun yarn woven fabrics for Korean folk clothes, stiffness, anti-drape stiffness are superior to those of polyester fabrics. And also, flexibility with soft feeling, scrooping feeling of core-spun yarn woven fabrics have greater values as compared with silk fabrics for Korean folk clothes.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1963-1966
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• 2005

Degenerative lumbar spinal stenosis(DLSS) is a disease inducing low back pain, leg pain, convulsion, numbness, and neurogenic claudication from compression of nerve root. Intervertebra fixation was reported to increase the degenerative of neighbor region after treatment. Recently, a new surgical technique of inserting a fixator between interspinous processes has been introduced. The purpose of this study is to design of the interspinous process fixator with flexibility to complement the trouble of using fixator in DLSS. This study evaluated the existing fixator through the mechanical test and modified fixators using the finite element analysis(FEA). Displacement, stiffness and Von-Mises stress were found to have similar values to those obtained from the mechanical test and the FEA in the biomechanical loading condition. Effects of variation in length and thickness were investigated to design an optimal fixator.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.3 s.180
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• pp.195-202
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• 2006

The degenerative lumbar spinal stenosis (DLSS) is a disease inducing low back pain, leg pain, convulsion. numbness, and neurogenic claudication from compression of nerve root. Intervertebra fixation was reported to increase the degeneration of neighbor lesion after treatment. Recently, a new surgical technique of inserting a fixator between interspinous processes has been introduced. The purpose of this study is to design the interspinous process fixator with flexibility to complement the trouble of using fixator in DLSS. This study evaluated the existing fixator through the mechanical test and modified it using the finite element analysis (FEA). The evaluation was based on the displacement, stiffness and von-Mises stress obtained from the mechanical test and calculated from the FEA in the biomechanical loading condition. Effects of variation in length and thickness were investigated to design an optimal fixator. Three prototypes were manufactured using FEA results. Mechanical tests under the biomechanical loading condition were performed to select the best one from these three. The selected fixator increased flexiblity by 32.9%.

• Structural Engineering and Mechanics
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• v.67 no.4
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• pp.417-425
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• 2018

The main aim of this paper is to investigate the bending of Euler-Bernouilli nano-beams made of bi-directional functionally graded materials (BDFGMs) using Eringen's non-local elasticity theory in the integral form with compare the differential form. To the best of the researchers' knowledge, in the literature, there is no study carried out into integral form of Eringen's non-local elasticity theory for bending analysis of BDFGM Euler-Bernoulli nano-beams with arbitrary functions. Material properties of nano-beam are assumed to change along the thickness and length directions according to arbitrary function. The approximate analytical solutions to the bending analysis of the BDFG nano-beam are derived by using the Rayleigh-Ritz method. The differential form of Eringen's non-local elasticity theory reveals with increasing size effect parameter, the flexibility of the nano-beam decreases, that this is unreasonable. This problem has been resolved in the integral form of the Eringen's model. For all boundary conditions, it is clearly seen that the integral form of Eringen's model predicts the softening effect of the non-local parameter as expected. Finally, the effects of changes of some important parameters such as material length scale, BDFG index on the values of deflection of nano-beam are studied.

• International Journal of Naval Architecture and Ocean Engineering
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• v.10 no.4
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• pp.520-528
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• 2018

This paper presents the results of experimental investigation on the elastic-plastic response of steel unstiffened wedges with dead-rise $10^{\circ}$ subjected to repeated impulsive pressure loadings. Repeated drop tests were performed with both wedge thickness and drop height varied. The pressure and histories were recorded during the tests and the permanent deflections were measured after every drop. Using the recorded test result, the effects of flexibility of wedges and repetition have been investigated. From the pressure history obtained from the tests the characteristics of the impulses were identified. Numerical simulations of the tests were made using the measured pressure history and the permanent deflection predictions were compared with those of the experiments.