• Journal of the Korea society of information convergence
• /
• v.6 no.1
• /
• pp.37-41
• /
• 2013

In this study, by using the Oculus Pentacam, we analyzed the relationship of corneal front astigmatism corneal and the radius of curvature of the rear face of the 20's to 40's. The vertical radius of curvature were man 7.94mm (${\pm}0.22$), women 7.87mm (${\pm}0.21$), the horizontal radius of the anterior corneal appeared man 7.69mm (${\pm}0.27$), women 7.63mm(${\pm}0.23$). And rear vertical radius of curvature were man 6.52mm(${\pm}0.23$), woman 6.55mm (${\pm}0.22$), the horizontal radius of the anterior corneal appeared man 6.06mm (${\pm}0.24$), woman 6.08mm(${\pm}0.24$). The results of correlation analysis between the radius of corneal posterior surface and the anterior corneal surface, it was found out that there is a significant correlation. In this study, similar results were obtained anterior surface of the cornea, the radius of curvature of the rear surface, the refractive power, and astigmatism, as other papers that have been reported. But in this paper, the cornea thickness was thicker than other previously reported paper.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.22 no.11
• /
• pp.1509-1520
• /
• 1998

An experiment was carried out for the fully developed turbulent flow of water in tube coils on the condition of uniform heat flux. The present work was conducted for various ranges for Dean number(1794~1321), Prandtl number (2.5~4.5), curvature ratio parameters (22~60). Heat transfer to steady viscous flow in coiled tubes of circular cross section was studied for fully developed velocity and temperature fields under the thermal boundary condition of uniform heat flux. The peripherally local Nusselt number correlated as a function of Dean and Prandtl numbers. We studied the flow in heat coiled tubes under the influence of both centrifugal and buoyancy forces in order to gain insight into the flow pattern. In the present study, we obtained three emperical formulas, $Nu_v=0.0231Re^{0.84}Pr^{0.4}(a/R)^{0.13}$ (vertical) $Nu_c=0.0241Re^{0.86}Pr^{0.4}(a/R)^{0.08}$ (corrugated) $Nu_h=0.0227Re^{0.84}Pr^{0.4}(a/R)^{0.09}$ (horizontal).

• Proceedings of the KSR Conference
• /
• 2011.05a
• /
• pp.842-848
• /
• 2011

The low-floor tram is a kind of railway vehicles which is operated on the street way track. For reducing the radius of curvature of the track, the tram consists of some carbody modules, and the articulation systems connect and support these carbody modules. The kind of articulation systems would be the hinge type and the pitching type. The hinge type articulation could allow only the yawing motion of the carbody modules, and the pitching type articulation could allow the pitching and yawing motions of the carbody modules simultaneously. With these function of the articulation systems, the tram could be operated on the horizontal and vertical curvature of the track. The number of each type of articulation could be decided with the number of carbody modules, and the manufacturer would decided the position of each type of the articulation in the view of the stability of carbody modules in the operation condition.

• 한국전산유체공학회:학술대회논문집
• /
• 2009.11a
• /
• pp.218-222
• /
• 2009

A level-set (LS) method is presented for computation of boiling phenomena which involve liquid-vapor interfaces that evolve, merge and break up in time, the flow and temperature fields influenced by the interfacial motion, and the microlayer that forms between the solid and the vapor phase near the wall. The LS formulation for tracking the phase interfaces is modified to include the effects of phase change on the liquid-vapor interface and contact angle on the liquid-vapor-solid interline. The LS method can calculate an interface curvature accurately by using a smooth distance function. Also, it is straightforward to implement for two-phase flows in complex geometries. The numerical method is applied for analysis of nucleate boiling on a horizontal surface and film boiling on a horizontal cylinder.

• Journal of Ocean Engineering and Technology
• /
• v.25 no.2
• /
• pp.62-66
• /
• 2011

In this paper, a liquid-filled long membrane container resting on a horizontal foundation is considered. All of the quantities are normalized to obtain similarity solutions. A system of nonlinear ordinary differential equations with undetermined boundary conditions is solved analytically. The integration of the curvature gives the solutions, which are expressed in terms of the elliptic integrals. A method for finding the shape and characteristic values is proposed for a given cross-sectional volume. The validity of these solutions is confirmed, and some results are shown for characteristic values and shapes.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.19 no.9
• /
• pp.2249-2260
• /
• 1995

An experiment of close contact melting of phase-change medium partially filled in an isothermally heated horizontal cylinder is performed which involves the volume expansion of liquid induced by the solid-liquid density difference. The solid-liquid interface motion and the free surface behavior of liquid were reported photographically. The experimental results show that the curvature of upper solid-liquid interface varied to flat as melting progresses. In addition to the varying interface shape, the melting rate increases with the lower initial height of solid and the free surface height of liquid increases linearly. The experimental results of molten mass fraction were expressed in a function of dimensionless time Fo.Ste$^{3}$4/ and agreed well with the analytical solutions.

• Bulletin of the Korean Mathematical Society
• /
• v.49 no.5
• /
• pp.1089-1099
• /
• 2012

We construct three kinds of complete embedded singly-periodic minimal surfaces in $\mathbb{H}^2{\times}\mathbb{R}$. The first one is a 1-parameter family of minimal surfaces which is asymptotic to a horizontal plane and a vertical plane; the second one is a 2-parameter family of minimal surfaces which has a fundamental piece of finite total curvature and is asymptotic to a finite number of vertical planes; the last one is a 2-parameter family of minimal surfaces which fill $\mathbb{H}^2{\times}\mathbb{R}$ by finite Scherk's towers.

• The Journal of the Acoustical Society of Korea
• /
• v.20 no.6
• /
• pp.75-81
• /
• 2001

In this paper we analyzed the localization error of near-field detection algorithm in the sea. The near-field detection algorithms using triangulation and wavefront curvature basically assume a signal in two dimension of bearing and range. But the assumption causes localization error because there is three dimension of bearing, range, and depth in the sea. Even through three dimensional effect is considered, the localization error is occurred if multipath propagation in the sea is ignored. To analyze the localization error in the sea, we simulate the near-field localization using acoustic propagation model and focused beamforming considering wavefront curvature. The simulation results indicate that localization error always occurs in the sea and the error varied with sound velocity profile, water depth, bottom slope, source range, etc.

• Journal of the Korean Society for Railway
• /
• v.16 no.4
• /
• pp.311-317
• /
• 2013

In railway construction, superimposition of horizontal and vertical curves has critical effects on the running stability and the ride comfort of vehicles as well as on construction costs. In this study, running safety, ride comfort, and track acting forces were analyzed by a numerical analysis using the VAMPIRE program according to cases of superimposition of vertical and horizontal curves. From the analysis results, it was found that running safety, riding comfort, and track acting forces in the case of superimposition of vertical and horizontal curves as well as vertical and transition curves meet all of the criteria. Also, in the case of the superimposition of vertical curves and curvature change between horizontal transition curves and circular curves meet all of the criteria.

• The Research Journal of the Costume Culture
• /
• v.24 no.3
• /
• pp.358-366
• /
• 2016

This study was performed to measure the posture correction effect of wearing ergonomic experimental clothing. Two types of experimental clothing (A, B) were developed. Both of them reinforced the muscles surrounding the spine. Experimental clothing A was developed by reflecting the shape and position of the pectoralis major muscle, abdominal muscle, and latissimus dorsi muscle. Experiment clothing B was developed by reflecting the integrated form of those muscles. Subjects were males in their 20s~30s (n=32). They were divided into two groups based on their acromion distance (AD): the turtle neck syndrome group (n=16, AD=3.81cm) and the normal group (n=16, AD=1.27cm). The correction of body posture was detected by three index values: change of the cervical curvature angle, horizontal distance between the seventh cervical vertebra and tragion, and AD. The comfort and tightness of the clothing were also measured. The results showed that both types of experimental clothing corrected body posture and that turtle neck syndrome can be prevented by wearing these types of posture correcting clothing. Two index values were decreased: cervical curvature angle ($0.31{\sim}1.32^{\circ}$) and horizontal distance between seventh cervical vertebra and tragion (0.22~0.31cm). The chest was also stretched. The comfort was rated as good for both types of experimental clothing. These results indicate that the experimental clothing had a posture correction effect without any discomfort for daily living.