• Korean Journal of Optics and Photonics
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• v.12 no.3
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• pp.235-239
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• 2001

In this paper, we propose an optical configuration of a reflective AFLC display mode using a half-wave AFLC cell in which inplane tilt angle is $22.5^{\circ}C$. To check the validity of our design, we fabricate a reflective half-wave AFLC cell of which the in-plane tilt angle is $24.9^{\circ}C$, and measure viewing angle and visible spectra characteristics. In the results, the half-wave AFLC cell in the reflective configuration exhibits wide viewing-angle as well as high brightness and contrast. trast.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.14 no.9
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• pp.725-733
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• 2002

In this study, the heat transport limitations of a two-phase closed thermosyphon were investigated. For the test, a two-phase closed thermosyphon ($L_t/: 600 mm,\;L_e:105mm,\;L_a:75mm,\;L_c:420mm,\;D_o:22.2mm,$ container: copper (inner grooved surface), working fluid: PFC ($C_6F_14$) was fabricated with a reservoir that can change the fill charge ratio. The following was imposed as the factors on the heat transport limitations of a two-phase closed thermosyphon. 1) Fill charge ratio of the working fluid. 2) Tilt angle of the longitudinal axis. From tile experimental data, some results were obtained as follows. When the fill charge ratio was relatively small ($\psi$20%), the heat transport limitation occurred about 100W by dry-out limitation. However over 40%, it shelved nearly constant value (500 W) by flooding limitation. The heat transport limitation according to the tilt angle increased smoothly until the tilt angle was $60^{\circ}$,/TEX>, after then decreased slowly.

• Physical Therapy Rehabilitation Science
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• v.9 no.3
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• pp.191-196
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• 2020

Objective: Congenital muscular torticollis (CMT) is a disease with abnormal head and neck posture in infants. It affects the child's movement and development and can lead to complications. Therefore, this study aims to find out what factors influence the rehabilitation treatment duration of infants with CMT. Design: Cross-sectional study. Methods: The subjects were 63 infants under 90 days of age who were diagnosed with CMT. Age, thickness of the sternocleidomastoid muscle (SCM) on the affected and non-affected side, head tilt angle, and head rotation angle of the affected head in infants were collected. The ratio of muscle thickness was calculated from the thickness of the affected SCM and the thickness of the non-affected SCM (A/N ratio). All subjects underwent conservative physical therapy twice a week for 30 minutes, and the end of the treatment was when the angle of head tilt was normal or less than 5 degrees, and the treatment duration was calculated. Results: Age, thickness of affected SCM, and head tilt were significantly correlated with treatment duration (p<0.05). The thickness of the non-affected SCM, A/N ratio, and head rotation angle did not show any correlation with treatment duration. The factors affecting the treatment duration were head tilt and age, showing 21% explanatory power of adjusted R². Conclusions: The main factors affecting the treatment duration of infants with CMT are head tilt and age. Therefore, more attention should be directed to the infant's head tilt and age for effective physical therapy of infants with CMT.

• Physical Therapy Korea
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• v.13 no.4
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• pp.56-63
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• 2006

This study examined the effects of the abdominal drawing-in (ADI) maneuver using a pressure biofeedback on muscle recruitment pattern of erector spinae and hip extensors and anterior pelvic tilt during hip extension in the prone position. Fourteen able-bodied volunteers, who had no medical history of lower extremity or lumbar spine disease, were recruited for this study. The muscle onset time of erector spinae, gluteus maximus, and medial hamstring and angle of anterior pelvic tilt during hip extension in prone position were measured in two conditions: ADI maneuver condition and non-ADI maneuver condition. Muscle onset time was measured using a surface electromyography (EMG). Kinematic data for angle of anterior pelvic tilt were measured using a motion analysis system. The muscle onset time and angle of anterior pelvic tilt were compared using a paired t-test. The study showed that in ADI maneuver during hip extension in prone position, the muscle onset time for the erector spinae was delayed significantly by a mean of 43.20 ms (SD 43.12), and the onset time for the gluteus maximus preceded significantly by a mean of -4.83 ms (SD 14.10) compared to non-ADI maneuver condition (p<.05). The angle of anterior pelvic tilt was significantly lower in the ADI maneuver condition by a mean of 7.03 degrees (SD 2.59) compared to non-ADI maneuver condition (15.01 degrees) (p<.05). The findings of this study indicated that prone hip extension with the ADI maneuver was an effective method to recruit the gluteus maximus earlier than erector spinae and to decrease anterior pelvic tilting.

• Physical Therapy Korea
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• v.26 no.1
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• pp.67-74
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• 2019

Background: Uncontrolled lumbopelvic movement leads to asymmetric symptoms and causes pain in the lumbar and pelvic regions. So many patients have uncontrolled lumbopelvic movement. Passive support devices are used for unstable lumbopelvic patient. So, we need to understand that influence of passive support on lumbopelvic stability. It is important to examine that using the pelvic belt on abdominal muscle activity, pelvic rotation and pelvic tilt. Objects: This study observed abdominal muscle activity, pelvic rotation and tilt angles were compared during active straight leg raise (ASLR) with and without pelvic compression belt. Methods: Sixteen healthy women were participated in this study. ASRL with and without pelvic compression belt was performed for 5 sec, until their leg touched the target bar that was set 20 cm above the base. Surface electromyography was recorded from rectus abdominis (RA), internal oblique abdominis (IO), and external oblique abdominis (EO) bilaterally. And pelvic rotation and tilt angles were measured by motion capture system. Results: There were significantly less activities of left EO (p=.042), right EO (p=.031), left IO (p=.039), right IO (p=.019), left RA (p=.044), and right RA (p=.042) and a greater right pelvic rotation angle (p=.008) and anterior pelvic tilt angle (p<.001) during ASLR with pelvic compression belt. Conclusion: These results showed that abdominal activity was reduced while the right pelvic rotation angle and anterior pelvic tilt angle were increased during ASLR with a pelvic compression belt. In other words, although pelvic compression belt could support abdominal muscle activity, it would be difficult to control pelvic movement. So pelvic belt would not be useful for controlled ASLR.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.5
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• pp.712-716
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• 2013

In solar generation, the PV array's azimuth is headed due south and the tilt is generally $33^{\circ}$ in order to acquire maximum generation. However, when installed in a site where there are buildings or other facilities, the azimuth and tilt are adjusted. Yet, when the azimuth and tilt are deviated from due south and $33^{\circ}$, the generation quantity is decreased substantially and currently a method to estimate the decreasing proportion is unavailable. Therefore, in this thesis, an equation on the "change ratio of solar radiation due to the changes in tilt and azimuth" was deduced by utilizing empirical data on the amount of solar radiation received according to the changes of tilt and azimuth and Interpolation. By using this equation, the decreasing proportion of generating quantity due to the installation methods of PV system can be estimated, therefore, it can be usefully utilized when designing and going through feasibility studies for development of solar generation systems.

• Korean Journal of Applied Biomechanics
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• v.21 no.1
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• pp.107-114
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• 2011

Closed kinematic chain exercises such as squatting have been widely indicated for knee rehabilitation in patients with patellofemoral disorders such as osteoarthritis and patellofemoral pain. Patellofemoral disorders are thought to be associated with abnormal patellar kinematics. In addition, the Q-angle may be undervalued in patients with patellofemoral pain and a laterally displaced patella. The purpose of this study was to assess patellar kinematics and the Q-angle during double-leg semi-squat and wall-slide semi-squat exercises. In this study, 28 asymptomatic subjects(16 male, 12 female) were assessed. Patellar tilt, patellar spin, and Q-angle were recorded using a motion analysis system during double-leg semi-squat and wall-slide semi-squat exercises. The Q-angle and patellar tilt were significantly increased, whereas patellar spin was significantly decreased, at $45^{\circ}$ of knee flexion compared with $0^{\circ}$. No differences were observed for the Q-angle, patellar tilt, and patellar spin during double-leg semi-squat and wall-slide semi-squat exercises. However, a significant interaction was observed between squat type and knee angle for patellar spin. We found that the patella is laterally tilted during semi-squat exercises and that there was no difference in patellar tracking between knee flexion during double-leg semi-squat and wall-slide semi-squat exercises.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.8 no.1
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• pp.1-12
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• 1996

In lots of application to heat exchanger systems, closed two-phase thermosyphons are tilted from a horizontal. If the tilt angle, especially, is less than 30$^{\circ}$, the operational performances of thermosyphon are highly dependent on tilt angle. The present study was conducted to better understand such operational behaviors as mech-anni는 of phase change, and flow patterns inside a tilted thermosyphon. For experiment, an ethanol thermosyphon with a 35% of fill charge rate was designed and manufactured, using a copper tube with a diameter 19mm and a length 1500mm. Through a series of test, the tilt angle was kept constant at each of 4 different values in the range 10~25deg. and the heat supply to the evaporator was stepwisely increased up to 30㎾/$m^2$. When a steady state was established to the thermosyphon for each step of thermal loads, the wall temperature distribution and vapor temperature at the condenser were measured. The wall temperature distributions demonstrated a formation of dry patch in the top end zone of the evaporator, with a values of temperature 20~4$0^{\circ}C$ higher than the wetted surface for a moderate heat flux q≒20㎾/$m^2$. Inspite of the presence of hot dry patch, however, the mean values of boiling heat transfer coefficient at the evaporator wall were still in a good agreement with those predicted by Rohsenow's formula, which was based on nucleate boiling. For the condenser, the wall temperatures were practically uniform, and the measured values of condensation heat transfer coefficient were 1.7 times higher than the predicted values obtained from Nusselt's film condensation theory on tilted plate. Using those two expressions, a correlation was formulated as a function of heat flux and tilt angle, to determine the total thermal resistance of a tilted thermosyphon. The correlation formula showed a good agreement with the experimental data within 20%.

• Journal of Biosystems Engineering
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• v.25 no.3
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• pp.233-240
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• 2000

A commercially available Doppler radar was modified and evaluated for on-board monitoring of ground speed. The radar output was corrected for pitch angle of aircraft based on the output of an electrolytic tilt sensor. The effects of aircraft speed, height and mounting angle on error in the ground speed were evaluated. The speed error decreased with an increase of the mounting angle since the radar contact angle with respect to the ground approached to the mounting angle. The error increased with an increase of the nominal aircraft speed. The altitude insignificantly affected the speed error. The Doppler radar provided acceptable percent errors within 5% in most measurements. The error can be reduced within ${\pm}$1.5% by increasing the mounting angle ($43^{\circ}$). The error of -3.8% at the mounting angle of $29^{\circ}$could be reduced by adjusting the mounting angle with respect to the radar contact angle.

• Fire Science and Engineering
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• v.23 no.5
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• pp.90-95
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• 2009

The wind is very important factor in forest fire spread. Flame spread has a change through wind pattern change in forest fire. In order to analyze the forest fire flame spread rate, change of flame tilt depending on wind may be considering first. This is be cause the flame spread rate varies by the flame tilt changed due to transfer of heat. Especially, as wind speed grow, flame gets closer to surface, heat transfer ratio increase, virgin fuel bed reaches ignition temperature more rapidly, and flame moves faster. This study deduces, through experiment and physical figure analysis, relations on the change behavior of flame tilt due to wind. The value of flame tilt angle calculated from the equation and the experiment value showed average error angle of $3.3^{\circ}$, which is relatively smaller than results of previous studies that used other coefficient. Froude number coefficient A can be calculated in the method provided in this research for estimation of flame tilt angle of virgin fuel bed with varying thermal properties. The research finding is expected to be applied to future studies on flame spread through numerical analysis of heat transfer.