• 한국광학회지
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• 제12권3호
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• pp.235-239
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• 2001

본논문에서는 반강유전성 액정의 in-plane tilt 각이 약 $22.5^{\circ}C$인 특성을 가진다는 것을 이용하여 액정의 위상지연을 $\lambda/2$로 설계한 광대역 $\lambda/4$필름을 사용한 단일 편광판 모드 반사형 LCD의 구조를 제안하였으며 이구조의 여러 가지 광특석을 전사모사 해보았다. 실제 실험에서는 in-plane tilt 각이 $\24.9\lambda$인 Chisso상의 CS-4001 반강유전성 액정을 사용하여 액정 셀의 위상지연을 $\lambda/2$로 설계하여 각도에 따른 반사특성과 파장에 따른 분광특성을 측정하였다.

• 설비공학논문집
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• 제14권9호
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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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• 제9권3호
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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.

• 한국전문물리치료학회지
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• 제13권4호
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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.

• 한국전문물리치료학회지
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• 제26권1호
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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.

• 전기학회논문지
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• 제62권5호
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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.

• 한국운동역학회지
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• 제21권1호
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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.

• 설비공학논문집
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• 제8권1호
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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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• 제25권3호
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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.

• 한국화재소방학회논문지
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• 제23권5호
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• pp.90-95
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• 2009

산불의 확산에 있어 바람은 매우 중요한 인자이다. 바람은 또한 지형에 따라 변화되며 이로 인해 다른 확산형태를 가지게 된다. 따라서 산불의 확산속도 해석을 위해 먼저 풍속에 따른 화염각 변화를 살펴볼 수 있다. 이는 바람에 의해 변화된 화염각으로 인해 미연소 지표 대상물에 열전달의 차이를 가져오기 때문이다. 풍속이 증가할수록 화염과 지표면이 가까워짐으로 인해 열전달이 증가되어 미연소물질이 착화온도에 빨리 도달하게 되어 화염의 확산속도가 빨라지게 된다. 따라서 본 연구에서는 바람에 의한 화염각 변화 산정식을 Froude number 관계식을 이용한 수치해석과 실험을 통해 제시하였다. 그 결과, Froude number 계수 A=1.85를 제시하였고 제시된 식에 대한 실험 화염각의 평균 오차각은 약 $3.3^{\circ}$로 다른 모델식에 비해 실험값과 유사한 결과를 나타내었다. 향후, 이 연구를 통해 열전달 수치해석을 통한 화염확산연구에 활용될 수 있을 것으로 사료된다.