• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.285-287
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• 2014

Equations of motion for the vibration analysis of rotating pre-twisted beams with functionally graded material properties are derived in this paper. Based on Timoshenko beam theory, the effects of shear and rotary inertia are considered. The pre-twisted beam has a rectangular cross-section and is mounted on a rotating rigid hub with a setting angle. Functionally graded material (FGM) properties are considered along the height direction of the beam. The equations of stretching and bending motion are derived by Kane's method employing hybrid deformation variables. To validate the derived equations, natural frequencies of a rotating FGM pre-twisted beam are compared to those obtained by a commercial software ANSYS. The effects of the pre-twisted angle, slenderness ratio, hub radius, volume fraction exponent, and angular speed on the modal characteristics of the system are investigated with the proposed model.

• Journal of the Microelectronics and Packaging Society
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• v.21 no.4
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• pp.69-76
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• 2014

In this study, we developed an ultra-thin flexible printed circuit board(FPCB) using the sputtered flexible copper clad laminate. In order to enhance the adhesion between copper and polyimide substrate, a NiMoNb addition layer was applied. The mechanical durability and flexibility of the ultra-thin FPCB were characterized by stretching, twisting, bending fatigue test, and peel test. The stretching test reveals that the ultra-thin FPCB can be stretched up to 7% without failure. The twisting test shows that the ultra-thin FPCB can withstand an angle of up to $120^{\circ}$. In addition, the bending fatigue test shows that the FPCB can withstand 10,000 bending cycles. Numerical analysis of the stress and strain during stretching indicates the strain and the maximum von Mises stress of the ultra-thin FPCB are comparable to those of the conventional FPCB. Even though the ultra-thin FPCB shows slightly lower durability than the conventional FPCB, the ultra-thin FPCB has enough durability and robustness to apply in industry.

• Journal of Interdisciplinary Genomics
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• v.1 no.2
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• pp.19-22
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• 2019

CATCH 22 syndrome is rare genetic disease that has various manifestations. Cervical vertebral anomaly, such as Klippel-Feil anomaly, is frequently observed in the patients with CATCH22 syndrome. We present the case of an 11-year-old female patient with CATCH22 syndrome and Klippel-Feil anomaly who had been treated torticollis using the customized soft neck collar. During the patient's first visit to our clinic, she presented with low ear set, skull deformity, intellectual disability, and tilting of the head to the left by approximately 25 degrees. Imaging studies revealed multisegmental fusion and C3 hemivertebrae of the cervical spine and left thoracic scoliosis at T4 with 50 degrees of Cobb's angle. We instructed passive stretching and applied the customized soft neck collar we invented. The ipsilateral aspect of the neck collar is designed to provide vertical support between the clavicle and mandibular angle and is adjustable in height. The Velcro was attached to the neck collar at the point of contact with the ipsilesional mandibular angle, which provides negative sensory feedback, inducing her to tilt neck to the contralesional side. We applied the neck collar for 2 hours a day. After 1 year of treatment, her neck inclination angle improved from 25 to 10 degrees. Providing negative sensory feedback using the customized soft neck collar can be one of the treatment options of postural management in patients with torticollis in cases of CATCH 22 syndrome combined with Klippel-Feil anomaly.

• Bulletin of the Korean Chemical Society
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• v.23 no.2
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• pp.253-261
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• 2002

Vibrational properties of ferrocyanide complex ion, $[Fe(CN)_6]^{4-}$ , have been studied based on the force constants obtained from the density functional calculations at B3LYP/$6-31G^{\ast\ast}$ level by means of the normal mode analysis using new bond angle and linear angle internal coordinates recently developed. Vibrations of ferrocyanide were manipulated by twenty-three symmetry force constants. The angled bending deformations of C-Fe-C, the linear bending deformations of Fe-C${\equiv}$N and the stretching vibrations of Fe-C have been quantitatively assigned to the calculated frequencies. The force constants in the internal coordinates employed in the modified Urey-Bradley type potential were evaluated on the density functional force field applied, and better interaction force constants in the internal coordinates have been proposed. The valence force constants in the general quadratic valence force field were also given. The stretch-stretch interaction and stretch-bending interaction constants are not sensitive to the geometrical displacement in the valence force field.

• Korean Journal of Occupational Health Nursing
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• v.9 no.1
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• pp.49-55
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• 2000

When standing, walking, or running for extended periods of time, fatigue occurs in the legs. Although there are many ways, to release tense or fatigued leg muscles, in the case that there is insufficient time to relax, an easy way to release leg fatigue is using an inclined step (about 3 minutes). This method was more effective than performing stretching exercises as studied. An experiment was conducted on a golf course in the Kangwon province in Korea. Subjects were chosen randomly and consisted of 5 females and 4 males golf caddies. Their main tasks consisted of pulling golf carts to the bottom of a hill for 8 to 10 hours and sometimes lifting and lowering golf clubs during the duration of one day. EMG was measured after work and after using the previously mentioned inclined Steps for the lower legs using ME3000P. This study investigated the types of inclined Steps which would be most effective and appropriate for golf caddies, whether sex difference had any influence existed between male and female workers. The results showed that a step with a $20^{\circ}$ angle was most effective for males and a step with a $25^{\circ}$ angle was most effective for females. Females showed faster recovery from fatigue than males. However, there were no statistical significance between males and females.

• Physical Therapy Korea
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• v.14 no.4
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• pp.58-65
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• 2007

The purpose of this study was to investigate the effects of serratus anterior strengthening exercises on scapular position and Visual Analog Scale (VAS) pain measurements taken at the resting position in young adults with adducted scapular. The exercise program included stretching of the scapular retractor and strengthening of the serratus anterior muscle. We measured the distance from the midline of the thorax to the vertebral border of the scapular with a tape line (Superior Kibler), and the distance from the 7th cervical spinous process to the acromial angle with 3-dimension motion analysis system, to compare the resting scapular position before and after exercise. Fifteen subjects with adducted scapular were recruited to compare the resting scapular position and VAS. The distance from 7th cervical spine process to acromial angle of the scapular and VAS decreased significantly (p<.01) after exercise, while the distance from the midline of the thorax to vertebral border of the scapular increased (p<.05). The conclusion is that the serratus anterior exercise program altered the resting scapular position and decreased VAS.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2004.10a
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• pp.319-324
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• 2004

Cross wedge rolling process is utilized to manufacture multi-stepped axis symmetrical parts. This process is generally performed under high temperature conditions in order to induce serious deformation. But cold cross wedge rolling process has been rarely studied due to the limits of deformation. Recently, the cold cross wedge rolling process has been utilized to enhance the material strength in specified parts of manufactured products. In this paper, experimental researches were carried out with various forming conditions of cold cross wedge rolling process in order to suggest the design guidance to make preform for cold cross wedge rolling. The tensile strength and the surface hardness of specified region were compared to that of initial material with the variation of the area reduction and the rotational speed of rolling die. With respect to the area reduction, the maximum tensile strength was linearly increased and the surface hardness was rapidly increased within lower percent of area reduction. The surface hardness was saturated over the rotational die speed of 0.8 RPM.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.10a
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• pp.293-296
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• 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
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• v.48 no.4
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• pp.519-545
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• 2013

An outline of the Timoshenko beam theory is presented. Two differential equations of motion in terms of deflection and rotation are comprised into single equation with deflection and analytical solutions of natural vibrations for different boundary conditions are given. Double frequency phenomenon for simply supported beam is investigated. The Timoshenko beam theory is modified by decomposition of total deflection into pure bending deflection and shear deflection, and total rotation into bending rotation and axial shear angle. The governing equations are condensed into two independent equations of motion, one for flexural and another for axial shear vibrations. Flexural vibrations of a simply supported, clamped and free beam are analysed by both theories and the same natural frequencies are obtained. That fact is proved in an analytical way. Axial shear vibrations are analogous to stretching vibrations on an axial elastic support, resulting in an additional response spectrum, as a novelty. Relationship between parameters in beam response functions of all type of vibrations is analysed.

• The Journal of the Acoustical Society of Korea
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• v.25 no.3E
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• pp.131-136
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• 2006

The PML developed for the radio wave propagation is a powerful numerical domain truncation technique. We perform an analytic study on the reflection from the PML inserted in the ocean bottom. In the ocean bottom, we show the PML to have the improved performance but simultaneously the degeneration below the critical angle of the fast ocean bottom. The degeneration of the PML can be simply relaxed by stretching the thickness of the PML or putting the attenuation coefficient to the ocean bottom. As a better solution, we propose the improved truncation technique based on the PML and the non-local boundary condition. Finally, we apply the PML to the acoustic wave propagation using split-step Pade PE solver. For the problems of the ocean waveguide, the numerical efficiency of the PML is examined and the usefulness of the PML is confirmed.