• Clinics in Shoulder and Elbow
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• 제21권3호
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• pp.151-157
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• 2018

Background: Nonunion of lateral humeral condyle fracture causes cubitus valgus deformity. Although corrective osteotomy or osteosynthesis can be considered, there are controversies regarding its treatment. To evaluate elbow joint biomechanics in non-united lateral humeral condyle fractures, we analyzed the motion of elbow joint and pseudo-joint via in vivo three-dimensional (3D) kinematics, using 3D images obtained by computed tomography (CT) scan. Methods: Eight non-united lateral humeral condyle fractures with cubitus valgus and 8 normal elbows were evaluated in this study. CT scan was performed at 3 different elbow positions (full flexion, $90^{\circ}$ flexion and full extension). With bone surface model, 3D elbow motion was reconstructed. We calculated the axis of rotation in both the normal and non-united joints, as well as the rotational movement of the ulno-humeral joint and pseudo-joint of non-united lateral condyle in 3D space from full extension to full flexion. Results: Ulno-humeral joint moved to the varus on the coronal plane during flexion, $25.45^{\circ}$ in the non-united cubitus valgus group and $-2.03^{\circ}$ in normal group, with statistically significant difference. Moreover, it moved to rotate externally on the axial plane $-26.75^{\circ}$ in the non-united cubitus valgus group and $-3.09^{\circ}$ in the normal group, with statistical significance. Movement of the pseudo-joint of fragment of lateral condyle showed irregular pattern. Conclusions: The non-united cubitus valgus group moved to the varus with external rotation during elbow flexion. The pseudo-joint showed a diverse and irregular motion. In vivo 3D motion analysis for the non-united cubitus valgus could be helpful to evaluate its kinematics.

• 한국운동역학회지
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• 제25권3호
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• pp.323-333
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• 2015

Objective : The purpose of this study was to investigate the changes of gait patterns and muscle activations with increased loads during stair walking. Also, it can be used as descriptive data about continuous stair walking in a real life setting. Method : Twelve sedentary young male adults(Age: $27.0{\pm}1.8yrs$, Weight: $65.8{\pm}9.9kg$) without any lower extremity injuries participated in this study. Participants performed stair walking up 7 floors and their ascending and descending motion on each floor was analyzed. A wireless electromyography(EMG) were attached on the Rectus Femoris(RF), Biceps Femoris(BF), Gastrocnemius(GN), Tibialis Anterior(TA) muscle to calculate integrated EMG(iEMG), median frequency(MDF) and co-contraction index(CI). Chest and left heel accelerometer signal were recorded by wireless accelerometer and those were used to calculate approximate entropy(ApEn) for analyzing gait pattern. All analyses were performed with SPSS 21.0 and for repeated measured ANOVA and Post-hoc was LSD. Results : During ascending stairs, there were a statistically significant difference in Walking time between 1-2nd and other floors(p=.000), GN iEMG between 2-3th and 6-7th(p=.043) floor, TA MDF between 1-2nd and 5-6th(p=.030), 6-7th(p=.015) floor and TA/GN CI between 2-3th and 6-7th(p=.038) floor and ApEn between 1-2nd and 6-7th(x: p=.003, y: p=.005, z: p=.006) floor. During descending stairs, there were a statistically significant difference in TA iEMG between the 6-5th and 3-2nd(p=.026) floor, and for the ApEn between the 1-2nd and 6-7th(x: p=.037, y: p=.000, z: p=.000) floor. Conclusion : Subjects showed more regular pattern and muscle activation response caused by regularity during ascending stairs. Regularity during the first part of stair-descending could be a sign of adaptation; however, complexity during the second part could be a strategy to decrease the impact.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1997년도 추계학술대회
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• pp.511-514
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• 1997

The objective of this study is to propose a finite element based design of the dental implant replacing unction and shape of natural teeth. For this, geometric actors were varied to investigate stress distribution of the alveolar bone around dental implant. In this study, the results were obtained based on the theory of linear elastic, with geometrically axisymmetric assumption. Geometric actors determining implant shape are ranged as 0.2mm-0.6mm, 0.04mm-0.1mm, 0.46mm-0.84mm or height of thread, radius of curvature of thread, and pitch, respectively. The stresses in the alveolar bone caused by biting force playa major role in determining implant stability. Especially, the stress concentration in the cortical bone causes bone resorption and finally makes the implant unstable. Therefore, the stress distributions were investigated on the side of the alveolar bone focusing on the area of cortical bone. The maximum von Mises stress was found to increase up to 6% as the height of thread increases, while its value was to decrease to 19% when the radius of curvature increase within the assigned ranges. For the variation of pitch, the larger size of pitch results in greater maximum von Mises stress when the length of the implant under consideration is fixed. The existence of the neck below the shoulder did not affect the stress distribution in the region of alveolar bone. However, the stresses on the side of the implant near the neck were found to be different by 20% approximately. Therefore, the neck can provide the stability of the implant against continuing biting movement. As a conclusion, the finite element based study shows a potential in designing the dental implant systematically.

• 한국운동역학회지
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• 제19권3호
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• pp.489-497
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• 2009

본 연구의 목적은 최대 수직점프시 개인내에서 발생하는 수행력의 차이와 이와 관련된 역학적 변인들의 영향을 규명하는데 있다. 이를 위해 20대 남성 20명을 대상으로 6회의 최대 수직점프를 실시하였으며, 이 가운데 최고 수행과 최저 수행을 추출한 후 수행력과 역학적 변인들을 비교, 분석하였다. 분석 결과, 우수수행과 비우수수행사이의 점프 높이는 약 4cm로 10% 정도의 유의한 차이를 보였으며 이는 이지시 중심의 높이(25%)와 이지속도(75%)에 기인하였다. 무릎관절과 엉덩관절의 역학적 출력은 유의한 차이가 나타나지 않은 반면 발목관절에서는 최대신전모멘트, 최대파워, 일량이 우수수행에서 유의하게 높았다. 최대수직점프에서 개인내 수행차는 주로 발목관절의 운동에 주로 기인한다고 할 수 있으며, 무릎과 엉덩관절의 역학적 출력은 수행력에 주요한 기여를 하지만 개인내 변이가 크지 않아 개인내 수행차에는 영향을 미치지 못하였다. 이에 비추어 점프력을 극대화하기 위해서는 트레이닝의 과정에서 발목관절의 역학적 출력을 증가시킬 수 있는 방안에도 보다 관심을 두어야 할 것으로 사료된다.

• 한국운동역학회지
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• 제26권3호
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• pp.315-321
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• 2016

Objective: The aim of this study was to analyze effects of the toe-spring angle of bobsleigh shoes on start speed lap time to develop Korean-specific bobsled shoes suitable for winter environments and for domestic players on the basis of sports science and optimized biomechanical performance. Method: Seven Korean bobsleigh athletes participated in this study, with three pairs of sprint spikes from three companies (Type A, Type B, Type C). To analyze sprint lap time and forefoot bending angle for each shoe, participants were instructed to drag a sled 15 meters from the start line at a maximum sprint. forefoot bending angle was collected by a high speed camera, and lap time speed was measured. Results: Lap time for type B shoes was $3.52{\pm}0.17sec$, type A was $3.55{\pm}0.19sec$, and type C was $3.56{\pm}0.18sec$. Forefoot bending angles were: angle 1, $6.88{\pm}5.55^{\circ}$; angle 2, $9.23{\pm}6.38^{\circ}$; angle 3, $15.56{\pm}5.39^{\circ}$; angle 4, $9.54{\pm}3.85^{\circ}$; angle 5, $9.22{\pm}5.08^{\circ}$; angle 6, $7.66{\pm}6.44^{\circ}$; and angle 7, $4.30{\pm}6.24^{\circ}$ (p<.001). Forefoot bending in angle 3 was as follows: type A, $16.47{\pm}6.01^{\circ}$; type B, $14.30{\pm}4.96^{\circ}$; and type C, $15.90{\pm}5.17^{\circ}$. Conclusion: Hard outsoles and midsoles are better than soft type for reduced start lap time when developing a prototype Korean bobsled shoe.

• 한국운동역학회지
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• 제17권4호
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• pp.201-208
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• 2007

The purpose of this study is to compare 4 different body punch types(type 1: a punch using a shoulder, type 2: a punch using a waist, type 3: a punch using lower extremities, and type 4: a punch with elbows by your side at chest level) in horseback-riding stance and establish suitable teaching theory and method, which would be a useful reference to Taekwondo instructors on the spot(in Taekwondo dojangs all around Korea). Five exhibition players from Korean national Taekwondo exhibition team participated in this study. Each participant was asked to perform the four different types of punches and their kinematic and kinetic data were recorded with 7 vicon cameras(125Hz) and two force plates(AMTI, 1200Hz). We analyzed displacement, time, resultant center of body mass trajectory, velocity, trunk angular velocity, and ground reaction force(GRF) from each body segment in body punch and the result. I performed 1-way ANOVA(RM) for average values of each player after standardization and statistical significance was set as p<.05. was as the following ; First, they showed a tendency to take the body punch posture with the biggest motion at a shoulder and on descending order a waist and a knee. Second, a mean time for each body punch on ascending order 0.46sec. for type 2, 0.49sec for type 3, 0.50sec. for type 4, and 0.56sec. for type 1. Third, a mean resultant center of body mass trajectory for each body punch the longest 4.07cm for type 3 and the shortest 2.458cm for type 1. Fourth, a mean of maximal velocity of a fist strike was the fastest 5.99m/s for type 3, 5.93m/s for type 4, 5.67m/s for type 2, and 5.01m/s for type 1 on the descending order. Fifth, a mean of maximal trunk angular velocity of the fastest 495.6deg./sec. for type 4 and 337.7deg./sec. for type 1 on the descending order. Sixth, strongest value was type 3, 2 for anterior-posterior ground reaction force(left -54.89N, right 60.58N), type 4 for medial-lateral GRF(left 83.59N, right -80.12N), and type 3 for vertical GRF(left 341.79N, right 426.11N).

• 생명과학회지
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• 제16권5호
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• pp.773-779
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• 2006

단축범위 무릎인공관절 수술자와 다축범위 무릎인공관절 수술자를 대상으로 앉았다 일어나는 동안 운동학적 및 운동역학적 요인들을 비교분석한 결과는 다음과 같다. 앉았다 일어나는 동작은 다축범위 수술자 집단이 단축범위 수술자 집단보다 0.19초(p= 0.033) 빠르게 나타났다. 최대상체 굴곡각도는 다축범위 수술자 집단이 단축범위 수술자집단 보다 $10^{\circ}(p=0.014)$정도 크게 나타났다. 상체굴곡 각속도는 다축범위 수술자 집단이 단축범위 수술자 집단보다 $7^{\Omega}{\cdot}S^{-1}$(p= 0.058)빠르게 나타났다. 단축범위 수술자 집단과 다축범위 수술자 집단의 ADD와 ABD의 차이는 거의 없었다. 대퇴사두근의 근전도분석은 내측광근은 무릎굴곡각 $60^{\Omega}-15^{\Omega}$(p＜0.05)에서 단축범위 수술자 집단 근전도 값이 다축범위 수술자집단 근전도값 보다 작게 나타났다. 외측광근은 무릎굴곡각 $60^{\Omega}-45^{\Omega}$(p＜0.05)에서 단축범위 수술자 집단 근전도 값이 다축범위 수술자집단 근전도값 보다 작게 나타났다. 대퇴직근의 값은 무릎굴곡각 $60^{\Omega}-30^{\Omega}$(p<0.05)에서 단축범위 수술자 집단 근전도 값이 다축범위 수술자집단 근전도값 보다 작게 나타났다. 대퇴이두근의 값은 무릎굴곡각 $75^{\Omega}-15^{\Omega}$(p＜0.05)에서 단축범위 수술자 집단 근전도 값이 다축범위 수술자집단 근전도값 보다 작게 나타났다.

• 한국운동역학회지
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• 제26권1호
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• pp.21-30
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• 2016

Objective: This study aimed to examine the characteristics of joint kinematics and synchronicity of rowing motion between elite and non-elite rowers. Methods: Two elite and two non-elite rowers performed rowing strokes (3 trials, 20 strokes in each trial) at three different stroke rates (20, 30, 40 stroke/min) on two stationary rowing ergometers. The rowing motions of the rowers were captured using a 3-dimensional motion analysis system (8-infrared camera VICON system, Oxford, UK). The range of motion (RoM) of the knee, hip, and elbow joints on the sagittal plane, the lead time ($T_{Lead}$) and the drive time $T_{Drive}$) for each joint, and the elapsed time for the knee joint to maintain a fully extended position ($T_{Knee}$) during the stroke were analyzed and compared between elite and non-elite rowers. Synchronicity of the rowing motion within and between groups was examined using coefficients of variation (CV) of the $T_{Drive}$ for each joint. Results: Regardless of the stroke rate, the RoM of all joints were greater for the elite than for non-elite rowers, except for the RoMs of the knee joint at 30 stroke/min and the elbow joint at 40 stroke/min (p < .05). Although the $T_{Lead}$ at all stroke rates were the same between the groups, the $T_{Drive}$ for each joint was shorter for the elite than for the non-elite rowers. During the drive phase, elite rowers kept the fully extended knee joint angle longer than the non-elite rowers (p < .05). The CV values of the TDrive within each group were smaller for the elite compared with non-elite rowers, except for the CV values of the hip at all stroke/min and elbow at 40 stroke/min. Conclusion: The elite, compared with non-elite, rowers seem to be able to perform more powerful and efficient rowing strokes with large RoM and a short $T_{Drive}$ with the same $T_{Lead}$.

• 한국운동역학회지
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• 제19권2호
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• pp.297-309
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• 2009

이 연구에서는 피칭웨지 스윙 시 족저압력 측정기를 이용하여 평지, 오르막 내리막경사면에서의 족저압력분포의 메카니즘을 분석하여 운동역학적인 기초자료를 제공하고자 피험자는 KPGA 3명, KLPGA 3명을 대상으로 족저압력분포를 측정한 후 스윙시간, 동작특성, 평균족저압력 그리고 최대족저압력을 분석한 결과 경사면의 형태변화에 따른 스윙동작 시 구간별 시간변인과 족저압력변인들을 종합적으로 분석 결과 경사면에서의 스윙동작은 백스윙 과정에서 하지의 코일링 동작을 방해하는 요인이 될 수 있으며, 다운스윙과정에서도 체중분산을 최소화시키는 하지의 블로킹 동작과 이 후 릴리스 동작에도 부정적인 영향을 미치는 것으로 분석되었다. 또한 경사면은 스윙동작에 영향을 미칠 수 있는 많은 외적 요인들 중의 하나인데, 오르막경사면에서의 어드레스 자세는 하지의 움직임을 제한하기 때문에 약간 좁은 스탠스를 유지하고, 내리막경사에서는 반대로 하지의 더 큰 활동성을 막기 위하여 더 넓은 스탠스를 가져야 할 것으로 판단되며, 어드레스 자세에서 뿐만 아니라 오르막경사의 다운스윙 동안에도 가능한 신체균형을 유지시키기 위하여 체중을 왼발에 두어야 할 것으로 판단된다.

• 한국운동역학회지
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• 제17권1호
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• pp.191-199
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• 2007

This study was conducted to examine the biomechanical characteristics of open spike in the volleyball to improve the technique of the volleyball spike. The subjects were six male college and high school athletes. The motions of volleyball spike were filmed by using two Sony VX 2000 Video Cameras. The mechanical factors were angle and angular velocity of body segments in the upper and the lower limbs. The conclusions were as follows; 1. The angle of the shoulder joint of the skilled showed larger than that of the unskilled in impacting of the volley ball spike. 2. The angle of the elbow joint of the skilled showed larger than that of the unskilled in impacting of the volley ball spike. 3. The angle of the wrist joint of the skilled showed smaller than that of the unskilled in impacting of the volley ball spike. 4. The angle of the hip joint of skilled showed larger than that of unskilled in impacting of the volley ball spike. 5. The angle of the knee joint of the skilled and the unskilled showed same in take off and impacting of the volley ball spike, and that of the skilled showed smaller than that of the unskilled in take-off touchdown and touchdown after impact of the volley ball spike. 6. The angle of the ankle joint of skilled showed larger than unskilled in take-off of the volley ball spike. 7. The angular velocity of the shoulder joint, elbow joint, wrist joint of the skilled showed faster than that of the unskilled in impacting of the volley ball spike. Taken together the result of them, I have come to conclusion that knee joint angle in touchdown of the take off should be decreased and knee joint angle in take off should be increased, and then stability of the take off should be made and, and that extension of the elbow joint should be made and wrist joint angle decreased and shoulder and hip joint angle increased, and then C.O.G of the arm and hand should be positioned ahead C.O.G of the body in impacting for effective impact of the spike, and that the transfer of the angular velocity of body segments for effective impact of the spike make from the proximal segment to the distal segment at spike in volleyball.