• 한국자동차공학회논문집
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• 제1권3호
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• pp.22-33
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• 1993

A theoretical analysis of predicting the detailed motion of a piston-crank mechanism within piston-guide clearance is presented, and the analysis is applied to the piston motion in a gasoline engine. A piston movement program is developed to calculate the piston attitude relative to the bore, the piston to bore impact velocity and kinetic energy loss and the net transverse force acting on the piston. This paper presents the formulation of a set of differential equations governing the transverse and rotational motion of a piston. These equations of motion were solved by well established Runge-Kutta method. As a result of this study, it is possible to predict the effects of piston geometry and piston pin offset on a piston motion and kinetic energy loss.

• The Journal of Korean Physical Therapy
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• 제24권1호
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• pp.41-50
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• 2012

Purpose: This study examined the effect of an integrated kinetic program on the body composition of middle-aged and their associated blood lipid components. Methods: The subjects included 50 middle-aged women who resided at J city. Upon their agreements, the subjects were divided into either an experimental group or the control group. There were 25 subjects in each. The integrated kinetic program was conducted during the 6 weeks, and the experimental group was underwent its associated program 5 times a week. There were 3 subjects from each group that were excluded. The extensions were measured with the extensometer, the weights were taken with the body ingredient analysis instrument, and the blood lipid consistency with the blood autoanalyzer. Results: Pre- and Post- the integrated kinetic program, there were statistically significant differences between the body fat mass and the BMI in the experimental group. However, this difference was not significantly different in the control group. Further, there were no statistically significant differences between the two groups of all items in blood lipid components. But the experimental group showed the decrement from TC and TG items after accomplishing the program. Conclusion: The results of this study showed that this kinetic program helps the prevention and functional control of bodily functional decrement to middle-aged women. It is considered that follow-up studies on practically integrated kinetic programs are needed so that they include exercise accomplishments of proper period and good quality nutrition intake. This is in order to maintain muscular quantity and prevent muscle function decrement for the healthy middle-aged women, preparing in aging and menopause.

• 한국디자인학회:학술대회논문집
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• 한국디자인학회 2003년도 봄 학술발표대회논문집
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• pp.44-45
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• 2003

• 한국패션뷰티학회지
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• 제3권1호
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• pp.29-38
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• 2005

Nowadays, fashion is high evaluated as a mean of self expression as well as a formative art itself, The moderns' elevated beauty sense and strong desire for individuality expression have not only advanced various and refined fashion presentation but also led to expansion of fashion to a total coordination covering hair and makeup. Of them, hair styling does play an important role in rounding out the various image of fashion. It is not only far from omittable part but also, out of simplicity in the past, taking formative characteristics in form and structure day by day. Especially, artistic elements of modern arts are being introduced as motives, and of which representative is e introduction of kinetic art which is thought the artistic approval on mechanization trend in the 20th century. Thus, the study was intended to investigate how and in what forms the various features of kinetic arts is reflected in the modern hair shaping, and to suggest a new prospect of kinetic art-applied hair shaping.

• Journal of the Optical Society of Korea
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• 제13권1호
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• pp.42-47
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• 2009

The propagation of an intense laser pulse through an upward density-gradient plasma in a self-modulated laser wakefield acceleration (SM-LWFA) is investigated by using particle-in-cell (PIC) simulations. In the fully relativistic and kinetic PIC simulations, the relativistic and kinetic effects including Landau damping enhance the electron dephasing. This electron dephasing is the most important factor for limiting the energy of accelerated electrons. However, the electron dephasing, which is enhanced by relativistic and kinetic effects in the homogeneous plasma, can be forestalled through the detuning process arising from the longitudinal density gradient. Simulation results show that the detuning process can effectively maintain the coherence of the laser wake wave in the spatiotemporal wakefield pattern, hence considerable energy enhancement is achievable. The spatiotemporal profiles are analyzed for the detailed study on the relativistic and kinetic effects. In this paper, the optimum slope of the density gradient for increasing electron energy is presented for various laser intensities.

• 한국전문물리치료학회지
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• 제25권2호
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• pp.62-70
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• 2018

Background: The craniocervical flexion (CCF) exercise is one of the effective exercise in correcting forward head posture (FHP). However, some people with FHP achieve CCF with compensatory movements, for example, low cervical flexion using superficial neck flexors such as the sternocleidomastoid (SCM) muscle. No study has yet investigated whether a dual­pres ure biofeedback unit (D-PBU) method to prevent low cervical flexion would be helpful in performing pure CCF movement. Objects: The purpose of this study was to compare the effects of the CCF using D-PBU method and the traditional CCF method on the cross-sectional area (CSA) of the longus colli muscle (LCM) and the activity of SCM muscle in subjects with FHP. Methods: Twenty­four FHP subjects (male: 16, female: 8) were recruited for this study. All subjects performed CCF using two different methods: the traditional CCF method and the CCF using D-PBU method. The CSA of the LCM was measured via ultrasound, and surface electromyography was used to measure SCM muscle activity. Results: The change in CSA of the LCM was significantly larger during the CCF using D-PBU method ($1.28{\pm}.09$) compared with the traditional CCF method ($1.19{\pm}.08$) (p<.05). The SCM muscle activity using the CCF using D-PBU method ($2.01{\pm}1.97$ %MVIC) was significantly lower than when using the traditional CCF method ($2.79{\pm}2.32$ %MVIC) (p<.05). Conclusion: The CCF using D-PBU method can be recommended for increasing LCM activation and decreasing SCM muscle activity during CCF movement in subjects with FHP.

• 대한물리의학회지
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• 제6권2호
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• pp.215-223
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• 2011

Purpose: The purpose of this study was to determine the effect of leg muscle activation by applying proprioceptive neuromuscular facilitation (PNF) arm patterns to unilateral upper extremities under the condition of both open and closed kinetic chains in a seated position. Methods: Twenty-two healthy subjects participated in this study. Four PNF patterns were applied to each subject's unilateral upper extremity. EMG data were collected from the vastus medialis, biceps femoris, tibialis anterior and gastrocnemius. The measured EMG data were digitized and processed to root mean square (RMS) and expressed as percentage maximal voluntary isometric contraction (%MVIC). The data were analyzed using two-way analysis of variance (ANOVA) with repeated measures to determine the statistical significance. Results: The results of this study were summarized as follows: Firstly, in comparison to muscle activation of the biceps femoris, there was a significant increase in the D2 flexion pattern when it was compared with D2 extension pattern and when it was compared with D1 flexion pattern (p<.05). Secondly, there was a significant increase in the muscle activation of the vastus medialis and tibialis anterior with a closed kinetic chain rather than an open kinetic chain (p<.05). Conclusion: In conclusion, in order to increase muscle activation of the biceps femoris, the D2 flexion pattern can be applied, regardless of kinetic chain. In addition, in order to increase muscle activation of the vastus medialis and tibialis anterior, four arm patterns can be applied with a closed kinetic chain.

• 한국표면공학회지
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• 제41권6호
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• pp.255-263
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• 2008

Generally, deposition mechanism of diamond particle is mainly embedding effect in the kinetic spray process. Accordingly, in spite of high cost, helium gas was employed as process gas to get high diamond fraction in the composite coating. In this study, the deposition behavior of bronze/diamond by kinetic spray process was compared using different process gas (helium and nitrogen). Bare (mean size of $5{\mu}m$, $20{\mu}m$) and nickel coated diamond (mean size of $26{\mu}m$) were deposited on Al 6061-T6 substrate with fixed process temperature and pressure. For comparison with experimental results, plastic deformation behavior of nickel layer was simulated by finite element analysis (using ABAQUS/Explicit 6.7-2). The size, broken ratio, and fraction of diamond in the composite coating were analyzed through scanning electron microscopy and image analysis method. The uniform distribution and deposition efficiency of diamond particles in the coating layer could be achieved by tailoring the physical properties of the feedstock.

• Journal of Welding and Joining
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• 제25권4호
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• pp.35-41
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• 2007

In kinetic spraying process, the critical velocity is an important criterion which determines the deposition of a feedstock particle onto the substrate. In other studies, it was experimentally and numerically proven that the critical velocity is determined by the physical and mechanical properties and the state of materials such as initial temperature, size and the extent of oxidation. Compared to un-oxidized feedstock, oxidized feedstock required a greater kinetic energy of in-flight particle to break away oxide film during impact. The oxide film formed on the surface of particle and substrate is of a relatively higher brittleness and hardness than those of general metals. Because of its physical characteristics, the oxide significantly affected the deposition behavior and critical velocity. In this study, in order to investigate the effects of oxidation on the deposition behavior and critical velocity of feedstock, oxygen contents of Al feedstock were artificially controlled, individual particle impact tests were carried out and the velocities of in-flight Al feedstock was measured for a wide range of process gas conditions. As a result, as the oxygen contents of Al feedstock increased, the critical velocity increased.

• 대한핵의학회:학술대회논문집
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• 대한핵의학회 1969년도 제8차 학술대회
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• pp.3.1-3.1
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• 1969