• Korean Journal of Applied Biomechanics
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• v.23 no.3
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• pp.261-269
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• 2013

The purpose of this study was to investigate the degree of improvement of scoliosis, muscle function and VAS between the exercise group and the control group after conducting correct posture exercise program with 20 female students diagnosed with scoliosis through PAPS in M middle school for 12 weeks. The conclusion was as follows. Cobb's angle in exercise group was changed from $11.6^{\circ}{\ae}2.5^{\circ}\acute{y} $ to $7.3^{\circ}{\ae}2.0^{\circ}\acute{y} $ which was statistically significant difference (p<.001). However, the change in Cobb's angle was not significant in control group, hence there was no statistically significant difference. The limber back strength was changed from $45.9^{\circ}{\ae}8.7$ kg to $51.6^{\circ}{\ae}14.9$ kg and sit-up was changed from $13.7^{\circ}{\ae}5.1$ times to $12.9^{\circ}{\ae}5.3$ times in exercise group, but they were not statistically significant. Control group also showed no statistically significant change in back strength and sit-up. The degree of VAS was changed from $7.3^{\circ}{\ae}1.6$ to $3.3^{\circ}{\ae}2.4$ which was a statistically significant difference (p<.01) in exercise group. However, there was no statistically significant difference in control group. Consequently, correct posture exercise program was considered to be effective for the reduction of Cobb's angle and degree of VAS for middle school female students with scoliosis. Therefore the correct posture exercise program can be recommended for youth scoliosis to improve and prevent the body imbalance and ultimately for the health of the youths.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.12
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• pp.146-153
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• 2009

Recently, the common grounding systems are adapted in most large structures. Since the ground resistance is insufficient to evaluate the performance of grounding systems, it is needed to measure grounding impedance. Even though the methods of measuring grounding impedance of large grounding systems are presented in IEEE standard 81.2, but they have not been described in detail. In this paper, we present the accurate method of measuring grounding impedance based on the revised fall-of-potential method and measurement errors due to earth mutual resistance and ac mutual coupling depending on locating test electrodes at remote earth were examined for the 15[m]$\times$15[m] grounding grid. As a result, the measurement error due to earth mutual resistance is decreased when the distance to auxiliary electrodes increased. To get rid of measurement errors due to mutual coupling, the potential lead should be installed at a right angle to the current lead. When the angle between the potential and the current leads is an acute angle or an obtuse angle, the mutual couple voltage is positive or negative, respectively. Generally, the measurement errors due to mutual coupling with an obtuse angle route are lower than those with an acute angle route.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.939-942
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• 2008

Moir$\acute{e}$s are a natural interference phenomenon which occurs whenever a transparent regular pattern plate is overlapped on another regular pattern plate. In the contact-type 3 dimensional imaging systems, the moires are inherent because an image display panel is seen through a viewing zone forming optical plate. The mathematical analysis of moires in the systems shows that they can be minimized by the proper selection of overlapping angles between them. The angle is different for pixels with different aspect ratios.

• Proceedings of the KSME Conference
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• 2002.08a
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• pp.683-686
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• 2002

The hydrodynamic instability of the three-dimensional boundary-layer over a rotating disk has been numerically investigated for three cases flows using linear stability theory (i.e. Rossby number, Ro = -1, 0, and 1). Detailed numerical values of the disturbance wave number, wave frequency, azimuth angle, radius (Reynolds number, Re) and other characteristics have been calculated for $K{\acute{a}}rm{\acute{a}}n$, Ekman and $B{\"{o}}ewadt$ boundary-layer flows. Neutral curves for these flows are presented. Presented are the neutral stability results concerning the two instability modes (Type I and Type II) by using a two-point boundary value problem code COLUEW that was based upon the adaptive orthogonal collocation method using B-spline. The prediction from the present results on both instability modes among the three cases agrees with the previously known numerical and experimental data well.

• Steel and Composite Structures
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• v.22 no.6
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• pp.1261-1280
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• 2016

We study chaotic motion in a nonlinear laminated composite plate under subsonic fluid flow and a simultaneous external load in this paper. We derive equations of motion of the plate using the von-$K{\acute{a}}rm{\acute{a}}n^{\prime}s$ hypothesis and the Hamilton's principle. Galerkin's approach is adopted as the solution method. We then conduct a divergence analysis to obtain critical velocities of the transient flow. Melnikov's integral approach is used to find the critical parameters in which chaos takes place. Effects of different parameters including the aspect ratio, plate material and the ply angle in laminates on the critical flow speed are investigated. In a parametric study, we show that how the linear and nonlinear stiffness of the plate and the load frequency and amplitude would influence the chaotic behavior of the plate.

• Journal of the Korean Mathematical Society
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• v.49 no.4
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• pp.671-686
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• 2012

This paper mainly deals with the tilted Carath$\acute{e}$odory class by angle ${\lambda}$ ${\in}$ ($-{\pi}/2$, ${\pi}/2$), denoted by $P{\lambda}$) an element of which maps the unit disc into the tilted right half-plane {<${\omega}$ : Re $e^{i{\lambda}}{\omega}$ > 0}. Firstly we will characterize $P{\lambda}$ from different aspects, for example by subordination and convolution. Then various estimates of functionals over $P{\lambda}$ are deduced by considering these over the extreme points of $P{\lambda}$ or the knowledge of functional analysis. Finally some subsets of analytic functions related to $P{\lambda}$ including close-to-convex functions with argument ${\lambda}$, ${\lambda}$-spirallike functions and analytic functions whose derivative is in $P{\lambda}$ are also considered as applications.

• Journal of the Korean Society for Precision Engineering
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• v.32 no.12
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• pp.1023-1029
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• 2015

Laser-assisted machining (LAM) is one of the most effective methods for enhancing the machinability of difficult-to-cut materials, such as titanium alloys and various ceramics, and has been studied by many researchers. LAM is a method that facilitates machining by softening a workpiece using a laser heat source. The advantages of the LAM process are decreases in tool wear, cutting force, and surface roughness. However, when the material is over-heated, melting or burning can occur. This study analyzed the heat source distribution with regard to overlapping of preheating on the laser heating path with an acute angle, a right angle and obtuse angles. Then, a power reduction method was proposed to reduce the melting and burning of the workpiece.

• ALGAE
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• v.22 no.2
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• pp.87-93
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• 2007

Three ecotypes of the freshwater red alga Compsopogon coeruleus (Balbis) Montagne were recorded from different freshwater and brackish water habitats of Orissa state in the east coast of India. These three had persistent differences in their branching pattern, e.g. (i) acute angle between main axis and lateral branch, (ii) equal or near to right angle between main axis and lateral branch, and (iii) short spine-like outgrowth instead of a branch in older filaments, besides having differences in the length, breadth and thickness of cortex of the thallus. Morphological observation of these taxa, and the ecological characteristics of the habitat of their occurrence is presented.

• The Journal of Korean Physical Therapy
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• v.22 no.6
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• pp.21-28
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• 2010

Purpose: The purpose of this study was to investigate the kinematic adaptation of head and trunk to ascend stairs and a ramp. Subjects were healthy young adults. Three-dimensional kinematic patterns of head and trunk movements were examined during stair climbing and steeper ramp climbing. Methods: Fourteen young subjects with no history of chronic or acute musculoskeletal, cardiovascular or respiratory disorders took part in this experiment. Kinematic data were collected using a 6 camera Vicon system (Oxford Metrix, Oxford, England). Repeated measures ANOVA analyses were used to investigate the effect of gait mode on kinematics of the head and trunk. Results: The angle of the trunk while ascending stairs or a ramp was modified in three human planes (p<0.05). The angle of head and neck during the ascending of stairs or a ramp was not changed in the sagittal plane but was changed in the frontal and transverse planes (p<0.05). Conclusion: This study describes and discusses some basic kinematic mechanisms underlying the pattern of head and trunk changes during stair and ramp climbing and showed that postural adaptation of the head and trunk is necessary to maintain balance.

• Bulletin of the Society of Naval Architects of Korea
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• v.20 no.2
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• pp.43-49
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• 1983

Stiffened plates, mostly used in the major part of ship and airplane structures, have been studied by various way-theoretical and experimental. In case of the fore and aft parts of the parallel middle body of ship structure, the stiffeners are not right-angled to the plate but acute angled. This paper presents the analysis of plates having included stiffeners by Finite Strip Method. The results of calculation show the influence of inclined angle which is less than $10^{\circ}$is ignorable. It is recommended that, when the inclined angle is over $20^{\circ}$, the section modulus of stiffener should be increased.