• Korean Journal of Applied Biomechanics
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• v.18 no.2
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• pp.85-94
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• 2008

The purpose of this study is to provide basic materials for amateur golf players or golf maniacs to learn desirable iron swing motions. This study compared and analyzed the swing motions of iron clubs(3, 6, 9) by using 3-D in three elite golf players. 1. There was no a great difference in the total of swing time by club and the time by phase was nearly similar. 2. There was no a difference in the change in a head location at address and impact by club. 3. The angle change in a right knee joint was similar by club except the difference according to the length of the club. 4. There was a subtle difference in hip rotation angle by club. 5. In each club, the same rotation angle of shoulder joint at address and impact motions contributed to accurate swing, and the maintenance of more than $90^{\circ}$ of shoulder rotation angle in top swing increased swing rotation. 6. Although subtle, the forward angle of upper body was increased with a shorter club. $30-36^{\circ}$ of forward angle of upper body was maintained at address, top swing, and impact motions.

• Korean Journal of Applied Biomechanics
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• v.16 no.2
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• pp.97-108
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• 2006

C. H. OH, S. N. CHOI, T. G. NAM, The Kinematic Analysis of the Tennis Flat Serve Motion, Korean Jiurnal of Sports Biomechanics, Vol. 16, No. 2, pp. 97-108, 2006. By the comparison and the analysis of the different factors during the tennis flat serve motion such as the required time per section, the movement displacement of the racket, the velocity of the upper limbs joints, the physical center of gravity, and the angle and the angular velocity of the upper limbs joints between an ace player and a mediocre player, these following results were drawn. First, the experiment result of the total time required per section in a tennis flat serve motion showed that an ace player was faster than a mediocre player by 0.4 seconds. This result suggested that it was required to increase the speed of the racket head by a swift swing to perform an effective flat serve motion. Second, the experiment result of the movement displacement of the racket in the tennis flat serve motion showed that an ace player greatly moved toward the left side on an x-axis. But both an ace and a mediocre player were shown to be at the similar points on a y-axis at the moment of the impact of the racket. An ace player was also shown to be located at a higher position on a z-axis by 0.23m. Third, the velocity of the center of gravity of an ace player was faster in every phase than that of a mediocre player in a tennis flat serve motion. Fourth, the velocity of the upper limb joints of an ace player was faster in every phase than that of a mediocre player in a tennis flat serve motion. Fifth, the experiment result of the speed of the racket head in tennis flat serve motion showed that a mediocre player was faster than an ace player in the first phase, but the latter was faster than the former in the second, third, and the fourth phases. Sixth, at the moment of impact of a tennis flat serve, an ace player had greater flexion of the angle of the wrist joints by an 11.8 degree than a mediocre player. An ace player also had greater extension of the angle of the elbow joint and the shoulder joint respectively by a 5.2 degree and a 1.4 degree with a mediocre player. Seventh, an ace player had greater angular velocity of the upper limb joints and the hip joints than a mediocre player at the moment of the impact of tennis flat serve. Eighth, an ace player was shown to have a greater change of the forward and the backward inclination (or the anterior and posterior inclination) of the upper body

• Journal of rehabilitation welfare engineering & assistive technology
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• v.9 no.2
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• pp.137-144
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• 2015

In this paper, we present an inertial sensor-based gait analysis system to measure and analyze lower-limb movements. We developed an integral AHRS(Attitude Heading Reference System) using a combination of rate gyroscope, accelerometer and magnetometer sensor signals. Several AHRS modules mounted on segments of the patient's body provide the quaternions representing the patient segments's orientation in space. And a method is also proposed for calculating three-dimensional inter-segment joint angle which is an important bio-mechanical measure for a variety of applications related to rehabilitation. To evaluate the performance of our AHRS module, the Vicon motion capture system, which offers millimeter resolution of 3D spatial displacements and orientations, is used as a reference. The evaluation resulted in a RMSE(Root Mean Square Error) of 1.08 and 1.72 degree in yaw and pitch angle. In order to evaluate the performance of our the gait analysis system, we compared the joint angle for the hip, knee and ankle with those provided by Vicon system. The result shows that our system will provide an in-depth insight into the effectiveness, appropriate level of care, and feedback of the rehabilitation process by performing real-time limb or gait analysis during the post-stroke recovery.

• Korean Journal of Applied Biomechanics
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• v.26 no.4
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• pp.343-351
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• 2016

Objective: The purpose of this study was to help improve game performance and provide preliminary data to enhance the efficiency of the kick and stability of the support foot by comparing the kinematic characteristics of the repeated side kick (geodeupyeopchagi) in poomsaeKoryo between expert and non-expert groups. Method: The subjects were divided into 2 groups according to proficiency in Taekwondo, an expert group and a non-expert group (n = 7 in each group), to observe the repeated side-kick technique. Four video cameras were set at a speed of 60 frames/sec and exposure time of 1/500 sec to measure the kinematic factors of the 2 groups. The Kwon3D XPprogramas used to collect and analyze three-dimensional spatial coordinates. Ground reaction force data were obtained through a force plate with a 1.200-Hz frequency. An independent samplesttest was performed, and statistical significance was defined as .05. The SPSS 18.0 software was used to calculate the mean and standard deviation of the kinematic factors and to identify the difference between the experts and non-experts. Results: The angular displacement of the hip joint in both the expert and non-expert groups showed statistical significance on E1 and E4 of the left support foot and E5 of the right foot (p<.05). The angle displacement of the knee joint in both groups showed statistical significance on E4 of the left support foot, and E1 and E2 of the right foot (p<.05). The angular velocity of the lower leg in both groups showed no statistical significance on the left support foot but showed statistical significance on E2 and E6 of the right foot (p<.05). The angular velocity of the foot in both groups showed no statistical significance on the left support foot but showed statistical significance on E2 of the right foot (p<.05). The vertical ground reaction force in both groups showed statistical significance on E2 (p<.05). The center of pressure in all directions in both groups showed statistical significance (p<.5). Conclusion: While performing the repeated side kick (geodeupyeopchagi), the experts maintainedconsistency and stability of the angle of the support leg while the kick foot moved high and fast. On the other hand, the angle of the support foot of non-experts appeared inconsistent, and the kick foot was raised, relying on the support leg, resulting in unstable and inaccurate movement.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.9
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• pp.3952-3958
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• 2011

This study was to investigate the difference in gait pattern between the visual handicap children and non handicap children in by analyze the biomechanical variation and pattern of lower limb. Therefore, we have made a choice of four visually handicapped children and two subjects, who had no medical disorder for the last six months. In order to collect the gait pattern data of each group, we have used six infrared cameras and one forceplate Also, we have used QTM program to collect the raw data and Visual3D program to calculate kinetic variable. The results were as follows, An/Posterior GRF of breaking phase and propulsion phase in stance phase was lower in visual handicapped children than that of non handicapped children and breaking phase was longer than propulsion phase. extension moment at the ankle was quite lower than general gait pattern and there was little variation at the knee joint which makes the results differ from the general gait pattern. However, hip joint moment was relatively higher than that of other joints. Mechanical variation of lower limb, in case of foot and shank, showed similar results. but generated very low mechanical energy. In thigh, the form of mechanical energy generation was slightly different in each group but generated more mechanical energy than other segments.

• Korean Journal of Applied Biomechanics
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• v.32 no.1
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• pp.17-23
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• 2022

Objective: The aim of this study was to investigate the effect Tiger-step walking on the movement of the lower extremities during walking. Method: Twenty healthy male adults who had no experience of musculoskeletal injuries on lower extremities in the last six months (age: 26.85 ± 3.28 yrs, height: 174.6 ± 3.72 cm, weight: 73.65 ± 7.48 kg) participated in this study. In this study, 7-segments whole-body model (pelvis, both side of thigh, shank and foot) was used and 29 reflective markers and cluster were attached to the body to identify the segments during the gait. A 3-dimensional motion analysis with 8 infrared cameras and 7 channeled EMG was performed to find the effect of tigerstep on uphill walking. To verify the tigerstep effect, a one-way ANOVA with a repeated measure was used and the statistical significance level was set at α=.05. Results: Firstly, Both Tiger-steps showed a significant increase in stance time and stride length compared with normal walking (p<.05), while both Tiger-steps shown significantly reduced cadence compared to normal walking (p<.05). Secondly, both Tiger-steps revealed significantly increased in hip and ankle joint range of motion compared with normal walking at all planes (p<.05). On the other hand, both Tiger-steps showed significantly increased knee joint range of motion compared with normal walking at the frontal and transverse planes (p<.05). Lastly, Gluteus maximus, biceps femoris, medial gastrocnemius, tibialis anterior of both tiger-step revealed significantly increased muscle activation compared with normal walking in gait cycle and stance phase (p<.05). On the other hand, in swing phase, the muscle activity of the vastus medialis, biceps femoris, tibialis anterior of both tiger-step significantly increased compared with those of normal walking (p <.05). Conclusion: As a result of this study, Tiger step revealed increased in 3d range of motion of lower extremity joints as well as the muscle activities associated with range of motion. These findings were evaluated as an increase in stride length, which is essential for efficient walking. Therefore, the finding of this study prove the effectiveness of the tiger step when walking uphill, and it is thought that it will help develop a more efficient tiger step in the future, which has not been scientifically proven.

• The Journal of the Korean bone and joint tumor society
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• v.9 no.1
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• pp.84-92
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• 2003

Purpose: To report two cases of bone tumors other than osteoid osteoma in the proximal femur and treated with percutaneous high frequency radioablation method. Cases: We reviewed two cases with intracortical chondroma and enchondroma in the femoral head retrospectively. The patient with intracortical chondroma was a thirty one year old woman and had suffered right hip pain of 1 year duration. The lesion was located in the head of right femur and treated with CT guided percutaneous high frequency radioablation after needle biopsy under general anesthesia. The symptom was gone immediately after the procedure and was discharged postop. 1 day. 15 months has passed without symptom recurrence. Second case having enchondroma, was 56 year old woman complaining of gluteal area pain for 3 months. Radiologic evaluation showed osteolytic lesion with sclerotic rim on the inferior portion of the left femoral head. She received a same therapy with CT guided radiofrequency ablation following needle biopsy. She reported dramatic pain relief after the procedure and was discharged postop. 1 day. No symptom has occurred for 3 months until now. Conclusion: We present 2 cases of bone tumor occurred in the hip joint area other than osteoid osteoma which were treated with CT guided radiofrequency ablation.

• The Korean Journal of Nuclear Medicine
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• v.33 no.4
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• pp.405-412
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• 1999

Purpose: It is important to evaluate the healing process of avascular necrosis (AVN) involving femoral head after treatment. The purpose of this study was to assess the usefulness of pinhole bone scintigraphy in the AVN of femoral head after surgery. Materials and Methods: We analyzed the changing pattern of pinhole bone scintigram in 21 femoral heads of 16 patients (14 lesions/11 male, 7 lesions/5 female, mean age: 39.4 yrs) before and after multiple drilling or vascularized bone grafting for AVN of the femoral head. In all patients, pre-operative scintigrams were obtained at 1 to 3 months before treatment and the first post-operative scintigrams were obtained at 1 to 3 months after treatment. All patients were followed for 2 to 4 years after operation. Results: The findings of the pinhole scintigrams were divided into three patterns: 1) curvilinear, 2) scattered spotty and 3) undetermined. The 10 of 11 lesions with curvilinear pattern had good postoperative clinical and radiological follow-up findings. However, all 6 lesions with scattered spotty pattern showed poor postoperative findings, which necessitated total hip joint replacement. Of the 4 lesions with undetermined pattern, 2 required total hip joint replacement. There was significant difference in postoperative prognosis between the curvilinear and scattered spotty patterns (p<0.05). Conclusion: We conclude that the pattern of pinhole bone scintigram obtained within 1 to 3 months after multiple drilling or vascularized bone graft operation is a useful prognostic indicator in the AVN of femoral head.

• Journal of Yeungnam Medical Science
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• v.2 no.1
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• pp.11-22
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• 1985

Femur neck fracture is well known as one of the major death cause after trauma in elderly patients, and unsolved fracture due to its frequent association with complications such as avascular necrosis and nonunion. Through meticulous evaluation of the patient, hip and surgeon's experiences, reduction of mortality and morbidity as well as rapid recovery of the patient to the preinjury social and ambulatory status without local complications and revision after treatment is urgently needed. Many factors about this fracture In itself were noted, but we have analyzed 18 femur neck fractures of the patients older than 50 years preliminarily according to age, fracture pattern, osteoporosis, etiology and method of treatment with its delay in association with major complications especially avascular necrosis and nonunion. The results are as follows; 1. Of these 18 fractures, 11 were in females, 8 were caused by minor trauma such as slip-down accident and 4 were associated with definite osteoporosis according to the Sing's classification. 2. Fracture pattern of these 18 are undisplaced in 4, displaced subcapital in 11, displaced transcervical in 3. 11 fractures in the patients older than 60 year are composed of 3 undisplaced or impacted fractures and 8 displaced subcapital fractures. 3. These 18 fractures were treated by closed reduction and Internal fixation with multiple pins in 13, and hemiarthroplasty in 4, but one was not treated to die after discharge from hospital. 4. 4 undisplaced or impacted fractures and 3 displaced transcervical fractures were not associated with any complications such as avascular necrosis or nonunion. But 4 of 6 displaced subcapital fractures were complicated by avascular necrosis, 3 of which were reduced in the varus position within 1 week, and the other was reduced in the good position on 1 week after trauma. There was no complication in 2 displaced subcapital fractures reduced in valgus position within 3 days after trauma. According to the above results, the prognosis of the femur neck fracture is dependent upon the fracture pattern and delay in its treatment. So it is inevitable to reduce the fracture in anatomical or valgus position as early as possible. But the arthroplasty may be needed in displaced subcapital fractures delayed for several days, with its reluction in extreme varus position or impossible and with pre-existing disease in the same hip Joint (total hip replacement).

• Journal of the Korean Orthopaedic Association
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• v.56 no.2
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• pp.125-133
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• 2021

Purpose: The clinical outcomes were investigated to determine if arthroscopic management is a useful method for 19 hips with iliopsoas tendon impingement (IPI) after total hip arthroplasty (THA). Materials and Methods: Eighteen patients (19 hips), who complained of groin pain and flexion pain that persisted after THA from September 2013 to December 2019, were the subjects of this investigation. The mean time to manifestation after THA was four months (range, 1-9 months) in patients of an average age of 60 years (range, 50-69 years). Thirteen out of 18 patients underwent THA using the direct anterior approach and five by the lateral approach. IPI was diagnosed by the medical history, physical examination, blood test, radiographic examination using X-ray and computed tomography, and topical injection therapy. All patients underwent arthroscopic treatment and a dynamic arthroscopic physical examination after exposure to the iliopsoas tendon revealed impingement. Tenotomy was then performed on the muscle portion through the total tendon portion. Symptoms and pain levels of preoperative, postoperative and follow-up period were investigated and compared. Results: The Western Ontario and McMaster Universities Osteoarthritis Index score decreased from an average of 58.4 (range, 40-88) before surgery to an average of 35.0 (range, 15-76) after surgery. Similarly, the visual analogue scale decreased from an average of 4.0 (range, 2-6) before surgery to an average of 1.4 (range, 0-4) after surgery. Sixteen patients (88.9%) showed pain relief and improvement in the straight leg raise test, and two patients showed postoperative muscle weakness and sustained pain. In the follow-up period, muscle weakness improved. One patient underwent arthroscopic iliopsoas tenotomy at the lesser trochanteric level but the symptoms persisted. The clinical symptoms were improved after one more tenotomy at the joint level. Conclusion: Arthroscopic iliopsoas tenotomy performed in patients with IPI after THA showed good clinical results.