• Tribology and Lubricants
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• v.35 no.6
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• pp.369-375
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• 2019

This paper presents a new method on how to calculate the thrust forces acting on an auto-leveling device in headlamps for passenger vehicles. The leveling device is used to lower the angle of lights when a load in the trunk of the vehicle lifts it. In the process of the headlamp design, it is imperative to predict the external forces so that the designers can decide whether to proceed or not. The device is composed of three pivot joints with no reaction moment, a plate that holds the lamp, and a leveling motor that changes rotation to linear motion. In this study, force balance, moment balance, and geometric compatibility are applied to the leveling device system so that a nonlinear system of equations can be derived; the multi-dimensional Newton-Raphson algorithm is then used to solve these. A sensitivity analysis is carried out to verify which design variables affect the system the most: the mass of the lamp and the height between the pivot and leveling device affect the thrust forces the most. Then, considering the friction forces between the moving parts, the hysteresis of the forces are derived. An experimental apparatus, designed and developed in this study, is used to verify the exactness of the derived equations. The results from experiments coincide well with the calculated results. The friction hysteresis, in particular, proves this upon analysis.

• Journal of the Korean Academy of Clinical Electrophysiology
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• v.8 no.1
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• pp.43-50
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• 2010

Purpose : The objective of this study is to effect of an aquatic rotation control and obstacle avoidance when conducted underwater on hemiplegia patient's balance ability and vestibular function. Methods : Twelve hemiplegia patients participated and were randomly assigned to a control group(I) with standard physical therapy and an aquatic group(II) with an aquatic rotation control, obstacle avoidance and standard physical therapy as well. The aquatic group trained using a Halliwick rotation control and obstacle avoidance through 3 times per week over 6 weeks. For all subjects, vestibular function, their balance, the change of electrooculogram (EOG), the change of accelerometer axis and torsiometer according to visual sense, vestibular sense with galvanic vestibular stimulation (GVS) or not during leg close stance were measured. Results : The EOG in the vertical and horizontal (p<0.05) were both significantly lowered. The change was significantly lower in the trajectory range of motion of trunk and spine with torsiometer when leg close stand (p<0.01) and leg close stand with GVS (p<0.01). The centre of gravity accelerated, there were reduced significantly difference X and Y axis of accelerometer during the closing of the leg without vision (p<0.05). There were reduced significantly difference X and Z axis of accelerometer during the closing of the leg with GVS (p<0.05). There were reduced significantly difference X and Z axis of accelerometer during the closing of the leg and close eyes with GVS (p<0.05). Conclusion : The balance ability, vestibular system and postural control is improved.

• Korean Journal of Adult Nursing
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• v.14 no.2
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• pp.222-232
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• 2002

Background and Purpose: After the coronary angiography procedure, patients are required to remain on bed rest to reduce the risk of bleeding and hematoma formation at the puncture site. This prolonged bed rest in the supine position is difficult for many patients, who frequently complain of low back pain. The purpose of the study was to determine whether a specially designed exercise therapy and transcutaneous electrical nerve stimulation (TENS) had an effect on the alleviation of low back pain. Method: Sixty-two patients were assigned to one of three groups : specially designed exercise therapy plus TENS plus general nursing care (exercise group N=21), general nursing care plus TENS (TENS group, N=23) or general nursing care (control group, N=18). The exercise therapy consisted of five movements including stretching, pelvic tilting, knee to chest, modified situps and trunk rotation with minimizing the motion of the puncture site. The severity of low back pain was assessed by a visual analogue scale(VAS) every two hours. The use of analgesic and any development of bleeding or other complications were monitored as well. The level of serum ${\beta}$-endorphin was determined before and after the three interventions. Result: The pain score of the exercise group was significantly lowered compared to that of the other groups. There was no difference in the serum ${\beta}$-endorphin level among three groups. Analgesic were less frequently taken by the exercise group. However the incidence of bleeding complications was not significantly different among the three groups. Conclusion: Exercise therapy is more effective than general care or TENS in alleviating low back pain of the patients with coronary angiography.

• Korean Journal of Applied Biomechanics
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• v.19 no.4
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• pp.761-770
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• 2009

The purpose of this study was to observe the kinematic patterns of hurdling by domestic hurdlers and elite hurdlers from other countries in particular, we studied the hurdling motion and joint angles at the third hurdle in 110-m hurdle races. There were slight differences in the following variables at takeoff and landing: angle of the center of gravity(elite hurdler, $34.14^{\circ}$ domestic hurdler, $24.89^{\circ}$), angle variables the body angle(elite hurdler, $4.27^{\circ}$ domestic hurdler, $6.37^{\circ}$), the angle of trunk inclination(elite hurdler, $3.18^{\circ}$ domestic hurdler, $11.58^{\circ}$), and the hip angle(elite hurdler, $40.1^{\circ}$ domestic hurdler, $43.2^{\circ}$).

• Journal of The Korean Society of Integrative Medicine
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• v.1 no.4
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• pp.57-66
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• 2013

PURPOSE: The purpose of this study was to investigate the effects using pressure biofeedback and teaching abdominal hollowing exercise on pelvic stabilization during the active straight leg raising test. METHOD: The subjects were divided into 3 groups who were fourty eight healthy participants, aged 20~25 years recruited for this study. First group wad control group. This group didn't any education. Second group was teaching them for a week. And last group was teaching abdominal hollowing exercise. The rotation angles of pelvic were measured by the motion anayalyser on flat surface and on form roll for the active leg raising. RESULT: Using pressure biofeedback and teaching abdominal hollowing exercise groups were significantly effective than control group in rotation angles of pelvis. And using pressure biofeedback group was more effective than teaching core stability muscles contraction group. CONCLUSION: This study suggested that patients with low back pain and pelvic instability can improve pelvic stabilization through pressure biofeedback and teaching abdominal hollowing exercise.

• Korean Journal of Applied Biomechanics
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• v.16 no.2
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• pp.193-205
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• 2006

This study was to analysis the kinematic and kinetic differences between new walking shoe(NWS : RYN) and general walking shoe(GWS). The subjects for this study were 10 male adults who had the walking pattern of rearfoot shrike with normal foot. The movement of one lower leg was measured using plantar pressure and Vicon Motion Analysis Program(6 MX13 and 2 MX40 cameras : 100 f / s) while the subjects walked at the velocity(1.5m/s. on 2m).. The results of this study was as follows : 1. The NWS was better than the GWS that caused injuries such as adduction, abduction and pronation are reduced While walking on a perpendicular surface, the landing angle and the knees angles were extensive which makes walking more safe which reduces anxiety and uneasiness. 2. The bottom of the NWS were now made into a more circular arch which supports the weight of the body and reduces the irregular angles when wearing GWS. This arch made the supporting area more wide which made the upholding the trunk of the body more effective. The whole bottom of the foot that supports the weight is more flexible in addition, increases the safeness of walking patterns and the momentum of the body. 3. The moment the heel of the foot of the NWS touch the ground, the range of the pressure were partially notable and the range of the pressure on the upper part of the thigh were dispersed The injuries that occurred while walking. primary factors when a shock related injuries are reduced Judgements of the impacts of the knees and the spinal column dispersing could be made.

• Korean Journal of Applied Biomechanics
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• v.14 no.1
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• pp.83-98
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• 2004

The purpose of this study was to determine the kinematic variables of the hurdling for a korea record holder (A) and a national hurdle representative (B). after the kinematic variables such the distance and the distance and height of C.G, the velocity and the angle were analyzed about the hurdling. The results were summarized as follows; 1. In terms of the distance and the height of C.G, subject A showed long in horizontal distance from C.G to the take-off phase, but showed short in the landing phase. Subject B showed short in horizontal distance from C.G to the take-off phase, and showed long in the landing phase. 2. In terms of the velocity of C.G, Subject A showed fast C.G velocity in horizontal direction to the braking phase, Subject A and B showed slower C.G velority in the landing phase, but Subject A showed height C.G velocity in vertical direction to the to the take-off, the landing, and propulsion phase 3. In terms of the angle of C.G and lean of C.G to front at the braking and the take-off phase. Subject A kept the less angle in the maximum trunk lean to front at the flight phase as comparison with Subject B. 4. In terms of the velocity of the knee and the ankle joint. Subject A showed fast in the resultant velocity of the left ankle joint the take-off phase, but showed slow in the left knee joint. Subject B showed fast in the resultant velocity of the left knee joint the take-off phase, but showed slow in the right knee and the right ankle joint.

• Korean Journal of Applied Biomechanics
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• v.17 no.1
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• pp.111-119
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• 2007

The purpose of this study was to investigate muscle activity and gait pattern in lower limb depending on the outsole of heel rockers. Fifteen healthy men volunteered for this experiment. Each subject performed totally three trails with two pairs of different heel rocker shoes and a pair of normal running shoes at speed of 1.33m/s for 1 minute during walking on a treadmill. Kinematic data gathered in 100Hz was recorded and analyzed by using the 3D motion capture system to measure the trunk tilt and joint angle of the right lower limb. And the lower extremity muscle activities were simultaneously recorded in 1000Hz and assessed by using EMG. The statistical analysis was the one-way ANOVA with the repeated measures to compare among the three kinds of shoes. The level of statistical significance for all tests was 0.05. Joint angle of lower limb was showed statistically significant different in MST(hip joint), LHS(ankle joint), and RTO(knee and ankle joint). Muscle activity of rectus femoris and biceps femoris was statistically increased in both heel rocker shoes during gait cycle on treadmill. The maximum peak time of tibialis anterior in the negative heel rocker showed the delay of approximately 23.8%time than normal shoes. Gait pattern variability of the negative heel rocker was increased in the first half of the stance phase and the variability of the positive heel rocker was increased in the terminal stance phase. In Conclusion, stability was decreased in between joints of lower limb on positive heel rocker than negative heel rocker. This study found that there were different joint angle, muscle activity, gait pattern and coordinate system of the lower limb in each kind of shoes. These unstability affected the lower extremity and the whole body. A further study has to be continued with study of rehabilitation and exercise for a long-term.

• Journal of Korean Physical Therapy Science
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• v.3 no.1
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• pp.919-927
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• 1996

Recently sports injuries are increasing due to the development of sports leisure industries as well as the increase of exercising population, and the study for sports injuries is needed more than before. Then the author studied the reasons for injuries, incidence rate, sites and sorts of sports injuries for the middle and high school football players during one year period from Jan. to Dec. 1994. The study subjects were 319 middle and high school players in Pusan and the method was questionnaire method. The results were as follows; 1. The average injury rate due to football play was 3.3 times per person for the 319 subjects during the last one year, and it was highest in goalkeeper as 4.6 times by position. 2. 68 % of the subjects did not receive periodic health examination, 74.9 % wore body protectors. The sports injuries due to football play occurred most commonly in soil play-ground(79.6 %), during training(52.3 %), and in winter time(33.7 %). 3. The commonly occurred injuries by motion were coalition(39.2 %), tackle(12.9 %), dribble (11.4 %) in order; those by sorts were contusion(34.4 %), sprain (32.9 %), spasm(9.0 %) ; and those by body portions lower extremities(82 %), trunk(17.6 %), upper extremities(12.5 %). 4. The frequently used treatment area was home care as in 42.7 % ; treatment methods were physical therapy, acupuncture/moxacautery, rest, operation in order; choices of treatment method were recommendation by coach/manager, and that by medical professional was the lowest as in 2.2 %. 5. If sports injury occurred during play, coach or manager let the players take rest in 56.2 %, but emergent management by medical professional was done only in 1.9 %. The return to play was decided mostly by the player himself(52.8 %), but that decided by a doctor was only in 1.0 %. In conclusion, to lessen the sports injuries due to football play, annual physical check-up, strengthening of play rules, improvement of playground, conditioning exercise, regulation of body protectors, and preventive training for expected injuries behaviors should be done and the decision to return to play and emergent management should be done by a medical professional as well. Football player, sports injury, injured body portions, sorts of injury, treatment method.

• Physical Therapy Korea
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• v.26 no.2
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• pp.1-7
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• 2019

Background: In previous studies, changes in postural alignment were found when the slope was changed during walking. Downhill walking straightens the trunk by shifting the line of gravity backward. Objects: This study investigated the effect of the downhill treadmill walking exercise (DTWE) on thoracic angle and thoracic erector spinae (TES) activation in subjects with thoracic kyphosis. Methods: A total of 20 subjects with thoracic kyphosis were recruited for this study. All the subjects performed the DTWE for 30 minutes. A surface EMG and 3D motion capture system were used to measure TES activation and thoracic angle before and after the DTWE. Paired t-tests were used to confirm the effect of the DTWE (p<.05). Results: Both the thoracic angle and TES activation had significantly increased after the DTWE compared to the baseline (p<.05). An increase in the thoracic angle indicates a decrease in kyphosis. Conclusion: The DTWE is effective for thoracic kyphosis patients as it decreases their kyphotic posture and increases the TES activation. Future longitudinal studies are required to investigate the long-term effects of the DTWE.