• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.47 no.2
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• pp.81-89
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• 2019

In this study, wind tunnel test on Quad-Tilt Propeller which has tandem wings is carried out to analyze the aerodynamic interference effect of front wing and propeller on rear wing during forward flight. Using 6-axis balance system, forces and moments of whole aircraft were measured and using strain gauge at wing root, bending moments were measured to observe change of aerodynamic force of each wings. A 12-hole probe was used to measure the flow field in the wing and propeller wake. Flow characteristics were observed qualitatively through flow visualization experiment using tuft and smoke. To measure the aerodynamic interference by elements, the influence of front wing and propeller on rear wing was analyzed by changing the wings and propellers mount combination.

• Journal of Korean Physical Therapy Science
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• v.2 no.3
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• pp.609-622
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• 1995

The purpose of this study was l)to compare a pelvic tilt angle between sound side and affected side in hemiplegic patients, 2)to determine the difference of weight bearing and weight shifting between sound and affected lower extremity according to the pelvic tilt angle. The subject for the study were 40 hemiplegic patients(mean age of 55.6 years)without orthopedic disability on pelvic bone. The data were analyzed by t-test, one way ANOVA, Multiple comparison and Range. The results of this study were as follows : 1. There was a significant difference in the pelvic tilt angle between sound side and affected side in hemiplegic patients(p<0.05). 2. There was a significant difference in the weight bearing value between sound and affected side in hemiplegic patients according to the posterior pelvic tilt angle(F = 12.43, df = 3/36, p<0.001). Therefore, the lesser the posterior pelvic tilt angle, the higher the weight bearing value on the affected side. 3. The lesser the posterior pelvic tilt angle, the higher the weight shifting value on the affected side. 4. There was a significant difference in weight bearing value between sound and affected side according to the grade spasticity(F = 3.61, df = 4/35, p<0.05). Therefore, the higher the grade spasticity, the lower the weight bearing value on affected side.

• Aerospace Engineering and Technology
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• v.4 no.1
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• pp.39-44
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• 2005

To validate the rotor performance analysis, 3D Computational Fluid Dynamics(CFD) analysis was performed for tilt rotor aeroacoustic model(TRAM). Also, 3D vehicle with rotating rotors was simulated for rotor power effect analysis. Multiple reference frame(MRF) and sliding mesh techniques were implemented to capture the effect of rotor revolution. CFD results were compared with the wind tunnel test results to validate their accuracy. At helicopter mode, CFD analysis predicted lower thrust than the wind tunnel test but CFD results showed good agreement with the test result at cruise mode. Rotor power effect decreased the lift but did not change drag and pitching moment.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.03a
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• pp.813-818
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• 2009

Shear properties of plastic bottle film/plastic bottle film and plastic bottle film/granitic soil which were evaluated from static friction tests. The monotonic shear experiments were performed by using an tilt table apparatus and large direct shear device. The test results showed that the friction angle of each interface and the interface depended on the amount of normal stress, the type of the interface used. Therefore, the testing method should be determined carefully by considering the type of loads and normal stress expected in the field with using the materials installed in the site.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2013.05a
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• pp.1345-1346
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• 2013

• 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.

• Journal of The Korean Society of Integrative Medicine
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• v.7 no.1
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• pp.81-88
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• 2019

Purpose : The purpose of this study was to examine if there is any correlation between pelvic tilt angle and trunk motion and trunk extensor during trunk forward flexion and to measure trunk motion, onset time of trunk motion, and onset time of trunk extensor activation. Methods : The subjects of this study were 42 healthy adults. The subjects had no back pain due to neurological disease and no experience of back surgery. After pelvic tilt angle was measured, each trunk forward flexion was performed three times. Trunk motion and onset time of trunk motion were measured using Myomotion. Four sensors were used, with one located at the upper thoracic (below $C_7$), the lower thoracic ($T_{12}-L_1$), the sacrum ($S_1$), and at the center of the anterior femur. Onset time of trunk extensors (spinalis, longissimus, gluteus medius, gluteus maximus, biceps femoris, and gastrocnemius) activation was measured using a wireless surface EMG. The EMG amplitude was normalized by using the reference voluntary contraction (RVC). The statistical significance of the results were evaluated using Pearson's correlation test. Results : The correlation between pelvic tilt angle and lumbar motion, onset time of pelvis motion, and onset time of gluteus medius activation was statistically significant in a positive direction (p<.05). The correlation between pelvic tilt angle with pelvis motion, onset time of lumbar motion, and onset time of longissimus activation showed a statistically significant negative correlation (p<.05). Conclusion : The study results provide a significant contribution to our understanding of the lumbar load at the initial stage of trunk flexion. Therefore, it may be possible to provide basic data for evaluation and treatment, such as orthodontic treatment for alignment of the spine and back pain. In addition, it is necessary to focus on normal exercise pattern reeducation as well as pelvic correction during exercise in daily life or in industrial fields.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.6 s.177
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• pp.1479-1490
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• 2000

The design process of the motor driven tilt/telescopic steering column is established by axiomatic design approach in conceptual design stage. By selecting independent design variables for improvin g performance of the steering system, each detailed design can be carried out independently. In the detailed design, the safety in crash environment and vibration reduction are considered. An occupant analysis code SAFE(Safety Analysis For occupant crash Environment) is utilized to simulate the body block test. Segments, contact ellipsoids and spring-damper elements are used to model the steering column in SAFE. The model is verified by the result of the body block test. After the model is validated, the energy absorbing components are designed using an orthogonal array. Occupant analyses are performed for the cases of the orthogonal array. Final design is determined for the minimum occupant injury. For vibrational analysis, a finite element model of the steering column is defined for the modal analysis. The model is validated by the vibration experiment. Size and shape variables are selected for the optimization process. An optimization is conducted to minimize the weight subjected to various constraints.

• The Journal of Korean Physical Therapy
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• v.31 no.1
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• pp.7-12
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• 2019

Purpose: This study examined the effects of stretching and strengthening exercises on the pain, pelvic tilt (PT), functional disability, and balance of patients with chronic lower back pain (CLBP). Methods: A total of 42 patients with CLBP were randomly divided randomly into either experimental group I (EG I, n=21), who received stretching exercise, or experimental group II (EG II, n=21), who received strengthening exercise. Both interventions were applied three times a week for eight weeks. Assessments were made with a visual analogue scale (VAS), PT, Oswestry disability index (ODI), and Berg's balance scale (BBS) before and after the eight weeks intervention period. A paired t-test was conducted to compare the within-group changes before and after the intervention. An independent t-test was used compare the between-group difference. The statistical significance level was set to ${\alpha}=0.05$ for all variables. Results: The EG I and II showed significant within-group changes in the VAS, PT, ODI, and BBS (p<0.05). The changes in VAS, PT, ODI, and BBS were similar regardless of the exercise form. Conclusion: In this study, the application of stretching and strengthening exercise for subjects who complain of CLBP was effective in changing the level of pain, PT, functional disability, and balance.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.2
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• pp.130-135
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• 2007

Wind tunnel test for Smart UAV power model has been conducted at KARI LSWT for about 3 months. The static model is used for the base plane and the power effect of tilt rotor is simulated by the tilt-rotor test rig installed in the test section. Although the genuine power effect is the difference between power-on and off tests. The existence of struts for power effect test produced unwanted form of interference and caused the change in flow angularity. To precisely evaluate power effect, a special approach is applied to Smart UAV test.