• Physical Therapy Korea
• /
• v.19 no.4
• /
• pp.24-31
• /
• 2012

The aim of this study was to investigate the effectiveness of self-stretching exercises for iliotibial band (ITB) (Side-lying; right hip and knee were flexed to support the pelvis while left hip was extended and adducted, Standing A; side-bending of the trunk on standing with crossed leg, Standing B; same as Standing A, except the hands were clasped overhead and shifted right side, and Standing C; same as Standing B, except moving the arms diagonally downward) to help determine the most effective self-stretching method to stretch ITB. Twenty-one healthy subjects who do not have ITB shortness from Yonsei University (14 men and 7 women) between the ages of 18 to 28 years voluntarily participated. Ultrasound was performed to measure the thickness of the ITB between the long axis of the ITB and the level parallel to the lateral femoral epicondyle during four self-stretching exercises. All data were found to approximate a normal distribution. We used a one-way repeated-measures analysis of variance (ANOVA) to compare the thickness of the ITB among all self-stretching exercises. The level of significance was set at ${\alpha}$=.05. The ANOVA was followed by Bonferroni's correction. The overall mean of ITB thickness was $1.14{\pm}.4$ mm (${\pm}$ standard deviation) in resting status. The change in the ITB thickness in percentages between the tested position of each self-stretching exercises and resting status was significant (p<.05) (Side-lying $26.62{\pm}10.18%$ with 95% confidence interval [CI]=21.99~31.25%; Standing A $29.46{\pm}16.19%$ with 95% CI=22.09~36.84%; Standing B $44.06{\pm}14.82%$ with 95% CI=37.31~50.81%; Standing C $53.76{\pm}12.1%$ with 95% CI=48.25~59.29%). Results indicated significant differences among four self-stretching exercises except Side-lying versus Standing A (p<.01). Based on these findings, the Standing C self-stretching exercise was the most effective in stretching the ITB thickness among four types of ITB self-stretching exercises. Additionally, the Side-lying self-stretching exercise using gravity to stretch the ITB is recommended as a low-load (low-intensity), long-duration stretch.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2009.10a
• /
• pp.293-296
• /
• 2009

In roll forming process, a sheet metal is continuously progressively formed into a product with required cross-section and longitudinal shape, such as a circular tube with required diameter, wall-thickness and straightness, by passing through a series of forming rolls in arranged in tandem. In recent years, that process is often applied to the bumper rail in the automotive industries. In this study, a optimal front side member manufacturing technology, model deign and proper roll-pass sequences can be suggested by forming number of roll-pass and bending angle. And also effects of the process parameters on the final shape formed by roll forming defects were evaluated.

• Structural Engineering and Mechanics
• /
• v.73 no.3
• /
• pp.259-269
• /
• 2020

In this paper, bending-stretching analysis of thick functionally graded piezoelectric rectangular plates is studied using the higher-order shear and normal deformable plate theory. On the basis of this theory, Legendre polynomials are used for approximating the components of displacement field. Also, the effects of both normal and shear deformations are encountered in the theory. The governing equations are derived using the principle of virtual work and variational approach. It is assumed that plate is made of piezoelectric materials with functionally graded distribution of material properties. Hence, exponential function is used to modify mechanical and electrical properties through the thickness of the plate. Finally, the effect of material properties, electrical boundary conditions and dimensions are investigated on the static response of plate. Also, it is shown that results of the presented model are close to the three dimensional elasticity solutions.

• Advances in materials Research
• /
• v.6 no.1
• /
• pp.45-63
• /
• 2017

In this article, static deflection and buckling of functionally graded (FG) nanoscale beams made of porous material are carried out based on the nonlocal Timoshenko beam model which captures the small scale influences. The exact position of neutral axis is fixed, to eliminate the stretching and bending coupling due to the unsymmetrical material change along the FG nanobeams thickness. The material properties of FG beam are graded through the thickness on the basis of the power-law form, which is modified to approximate the material properties with two models of porosity phases. By employing Hamilton's principle, the nonlocal governing equations of FG nanobeams are obtained and solved analytically for simply-supported boundary conditions via the Navier-type procedure. Numerical results for deflection and buckling of FG nanoscale beams are presented and validated with those existing in the literature. The influences of small scale parameter, power law index, porosity distribution and slenderness ratio on the static and stability responses of the FG nanobeams are all explored.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2016.02a
• /
• pp.244.1-244.1
• /
• 2016

Recently, the technology for flexible electronics such as flexible smart phone, foldable displays, and bendable battery is under active development. With approaching the real commercialization of flexible electronics, the electrical and mechanical reliability of flexible electronics have become significantly important because they will be used under various mechanical deformations such as bending, twisting, stretching, and so on. These mechanical deformations result in performance degradation of electronic devices due to several mechanical problems such as cracking, delamination, and fatigue. Therefore, the understanding of relationship between mechanical loading and electrical performance is one of the most critical issues in flexible electronics for expecting the lifetime of products. Here, we have investigated the effect of monotonic tensile and cyclic deformations on metal interconnect to provide a guideline for improving the reliability of flexible interconnect.

• Geomechanics and Engineering
• /
• v.18 no.2
• /
• pp.161-178
• /
• 2019

In this research, a simple quasi 3D hyperbolic shear deformation model is employed for bending and dynamic behavior of functionally graded (FG) plates resting on visco-Pasternak foundations. The important feature of this theory is that, it includes the thickness stretching effect with considering only 4 unknowns, which less than what is used in the First Order Shear Deformation (FSDT) theory. The visco­Pasternak's foundation is taken into account by adding the influence of damping to the usual foundation model which characterized by the linear Winkler's modulus and Pasternak's foundation modulus. The equations of motion for thick FG plates are obtained in the Hamilton principle. Analytical solutions for the bending and dynamic analysis are determined for simply supported plates resting on visco-Pasternak foundations. Some numerical results are presented to indicate the effects of material index, elastic foundation type, and damping coefficient of the foundation, on the bending and dynamic behavior of rectangular FG plates.

• Geomechanics and Engineering
• /
• v.14 no.6
• /
• pp.519-532
• /
• 2018

In this work, two dimensional (2D) and quasi three-dimensional (quasi-3D) HSDTs are proposed for bending and free vibration investigation of functionally graded (FG) plates using hyperbolic shape function. Unlike the existing HSDT, the proposed theories have a novel displacement field which include undetermined integral terms and contains fewer unknowns. The material properties of the plate is inhomogeneous and are considered to vary continuously in the thickness direction by three different distributions; power-law, exponential and Mori-Tanaka model, in terms of the volume fractions of the constituents. The governing equations which consider the effects of both transverse shear and thickness stretching are determined through the Hamilton's principle. The closed form solutions are deduced by employing Navier method and then fundamental frequencies are obtained by solving the results of eigenvalue problems. In-plane stress components have been determined by the constitutive equations of composite plates. The transverse stress components have been determined by integrating the 3D stress equilibrium equations in the thickness direction of the FG plate. The accuracy of the present formulation is demonstrated by comparisons with the different 2D, 3D and quasi-3D solutions available in the literature.

• Journal of the Microelectronics and Packaging Society
• /
• v.26 no.4
• /
• pp.55-62
• /
• 2019

Stiffness-gradient stretchable electronic packages of the soft PDMS/hard PDMS/FPCB structure were processed using the polydimethylsiloxane (PDMS) as the base substrate and the more stiff flexible printed circuit board (FPCB) as the island substrate. The elastic characteristics of the stretchable packages were estimated and their long-term reliabilities on stretching cycles and bending cycles were characterized. With 0.28 MPa, 1.74 MPa, and 1.85 GPa as the elastic moduli of the soft PDMS, hard PDMS, and FPCB, respectively, the effective elastic modulus of the soft PDMS/hard PDMS/FPCB package was estimated as 0.6 MPa. The resistance of the stretchable packages varied for 2.8~4.3% with stretching cycles ranging at 0~0.3 strain up to 15,000 cycles and for 0.9~1.5% with 15,000 bending cycles at a bending radius of 25 mm.

• The Journal of Korean Institute for Practical Engineering Education
• /
• v.3 no.1
• /
• pp.200-205
• /
• 2011

This research is first to analyze an electomygram reaction of the lower limbs among the muscles used during a back-round kicking of Taekwondo, second to analyze the relationship between the muscles of the kicking limb and those of the supporting limb, third to compare EMG activity of expert with novice. Measured muscles are as follows; rectus fermoris which control flexion and stretching of femora and knee joints, vastus medialis and vastus lateralis, which control flexion and stretching of legs, and biceps fermoris, which control stretching of femora, bending of knee joints and abduction of the crus. The electomygram reaction of all these selected muscles were analyzed. Three kicks were performed, and electomygram of each of kicks were measured. Then, electomygram reaction of the best kick was used for electomygram analysis.

• Proceedings of the Korean Society of Applied Pharmacology
• /
• 1993.04a
• /
• pp.141-141
• /
• 1993

말징버섯 Calvatia craniformis의 culture broth 40 liter를 여과하여 얻은 균사채를 열수 추출하여 진한 갈색 건조분말(Fr. A) 13.1g을 분리하였다. Fr. A에 대하여 DEAE-cellulose ion chromatography를 시행하여 중성분획인 흰색 분말 (Fr. B) 2.50g을, 산성분획인 갈색 분말 (Fr. C) 3.50g을 각각 분리하였다. Fr. B 500mg에 대하여 Sepharose CL-4B gel filtration chromatography를 시행하여 흰색분말 Fr. D(Calvatan) 350mg을 분리하였다. Calvatan 350mg에 대하여 Con A-Sepharose 4B affinity chromatography를 적용하여 미흡착 분획인 Fr. F($\alpha$-form)와 흡착 분획인 Fr. E ($\beta$-form)로 정제하였다. 항암작용의 기전을 구명하고자 마우스에 대하여 면역학적 실험을 시행하였다. macrophage의 활성에 대한 영향을 조사하였던 바, 투여군의 활성화된 macrophage에 의해 유리되는 superoxide anion의 양은 대조군에 비해 1.4배 증가하였고 Calvatan 투여군의 용혈반 형성세포(PFC)는 대조군에 비해 3.1배 증가하였다. 화학 분석에 의해, Calvatan은 다당체 87.2%, 단백질 1.8% 및 hexosamine 1.3%로 구성되어 있었다. 따라서 항암성 분획들은 protein-bound polysaccharide임을 알 수 있었다. 또한 각 분획의 다당체를 구성하고 있는 단당류는 glucose, galactose, mannose 및 xylose 였으며 단백질 부분은 16종의 아미노산으로 구성되어 있었다. IR 스펙트럼은 3300-3400 $cm^{－1}$에서 0-H stretching frequency, 2900 $cm^{－1}$ 에서 C-H stretching frequency, 1630 $cm^{－1}$ 에서 C-0 stretching frequency. 1000-1100 $cm^{－1}$에서 C-H 및 C-0 bending frequency를 나타내는 다당체의 전형적인 특성을 보여주었다.을 보여주었다.