• 한국운동역학회지
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• 제31권1호
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• pp.64-71
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• 2021

Objective: This study investigated the different in isokinetic peak strength of the knee joint, and kinetics and kinematics in drop landing pattern of lower limb between the patellofemoral pain syndrome (PFPS) patients and normal. Method: 30 adult females were divided into the PFPS (age: 23.13±2.77 yrs; height: 160.97±3.79 cm, weight: 51.19±4.86 kg) and normal group (age: 22.80±2.54 yrs, height: 164.40±5.77 cm, weight: 56.14±8.16 kg), with 15 subjects in each group. To examine the knee isokinetic peak strength, kinematics and kinetics in peak vertical ground reaction force during drop landing. Results: The knee peak torque (Nm) and relative strength (%) were significantly weaker PFPS group than normal group. In addition, PFPS group had significantly greater hip flexion angle (°) than normal group. Moreover, normal group had significantly greater moment of hip abduction, hip internal rotation, and left ankle eversion than PFPS group, and PFPS group had significantly greater moment of knee internal rotation. Finally, there was significant differences between the groups at anteroposterior center of pressure. Conclusion: The PFPS patients had weakened knee strength, and which can result in an unstable landing pattern and cause of more stress in the knee joints despite to effort of reduce vertical ground reaction force.

• 한국운동역학회지
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• 제34권2호
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• pp.81-92
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• 2024

Objective: The purpose of this study was to analyze the impact acceleration, shock attenuation and biomechanical variables at various running speed. Method: 20 subjects (height: 176.15 ± 0.63 cm, weight: 70.95 ± 9.77 kg, age: 27.00 ± 4.65 yrs.) participated in this study. The subjects ran at four different speeds (2.5 m/s, 3.0 m/s, 3.5 m/s, 4.0 m/s). Three-dimensional accelerometers were attached to the distal tibia, sternum and head. Gait parameters, biomechanical variables (lower extremity joint angle, moment, power and ground reaction force) and acceleration variables (impact acceleration, shock attenuation) were calculated during the stance phase of the running. Repeated measures ANOVA was used with an alpha level of .05. Results: In gait parameters, decreased stance time, increasing stride length and stride frequency with increasing running speed. And at swing time 2.5 m/s and 4.0 m/s was decreased compared to 3.0 m/s and 3.5 m/s. Biomechanical variables statistically increased with increasing running speed except knee joint ROM, maximum ankle dorsiflexion moment, and maximum hip flexion moment. In acceleration variables as the running speed increased (2.5 m/s to 4.0 m/s), the impact acceleration on the distal tibia increased by more than twice, while the sternum and head increased by approximately 1.1 and 1.2 times, respectively. And shock attenuation (tibia to head) increased as the running speed increased. Conclusion: When running speed increases, the magnitude and increasing rate of sternum and head acceleration are lower compared to the proximal tibia, while shock attenuation increases. This suggests that limiting trunk movement and increasing lower limb movement effectively reduce impact from increased shock. However, to fully understand the body's mechanism for reducing shock, further studies are needed with accelerometers attached to more segments to examine their relationship with kinematic variables.

• Steel and Composite Structures
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• 제18권5호
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• pp.1215-1237
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• 2015

The majority of connections in moment resisting frames are considered as being fully-rigid. Consequently, the real behavior of the connection, which has some level of flexibility, is ignored. This may result in inaccurate predictions of structural response. This study investigates the influence of flexibility of the extended end-plate connections in the steel moment frames. This is done at two levels. First, the actual micro-behavior of extended end-plate moment connections is explored with respect to joint flexibility. Then, the macro-behavior of frames with end-plate moment connections is investigated using modal, nonlinear static pushover and incremental dynamic analyses. In all models, the P-Delta effects along with material and geometrical nonlinearities were included in the analyses. Results revealed considerable differences between the behavior of the structural frame with connections modeled as fully-rigid versus those when flexibility was incorporated, specifically difference occurred in the natural periods, strength, and maximum inter-story drift angle.

• The Journal of Korean Physical Therapy
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• 제28권1호
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• pp.14-21
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• 2016

Purpose: The purpose of this study was to investigate examine how the kinematics and kinetics of lower limb joints were changed depending on the unstable shoes (US) during sit-to-stand task (SitTS). Methods: Nineteen healthy females were participated in this study. The subjects performed sit-to-stand task with US and barefoot. The experiment was repeated three times for each tasks with conditions. The kinematics and kinetics of lower limb joint were measured and analyzed using a 3-D motion analysis system. A paired t-test was utilised performed for to identificationy of changes in mean of angle, force, and moment between both the two conditions. Results: The results of this study showed kinematic differences in lower limb joints during SitTS based on the US. The hip, knee, and ankle angle showed statistically significant differences during SitTS. At the initial of SitTS, Tthe force and moment of the hip flexor, hip extensor, knee flexor, knee extensor, ankle flexor, and ankle extensor showed statistically significant differences. At the terminal of SitTS, Tthe force and moment of the hip flexor, hip extensor, knee flexor, knee extensor, ankle flexor, and ankle extensor showed statistically significant differences. At the maximum of SitTS, Tthe moment of the hip extensor showed statistically significant differences. The force and moment of the ankle flexor, extensor moment showed statistically significant differences. Conclusion: Therefore, Wwearing US is considered to influence on the lower limb joints kinematics and kinetics during SitTS movements, and thus suggests the possibility that of reducing the risks of pain, and osteoarthritis caused by changes in the loading of lower limb joints.

• 시큐리티연구
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• 제31호
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• pp.187-207
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• 2012

본 연구는 태권도의 기본동작인 주춤서기 자세에서의 주먹 지르기 동작을 3차원 입체영상분석을 통해 유형별로 운동학적 변인인 시간, 속도, 각도, 각속도, 각가속도 등을 분석하여 유형별 특성을 알아보고 올바른 주먹 지르기 동작의 지도방법을 제시하고자 하였다. 이를 위해 대학교 경호무도 태권도 경호무도시범단 3인을 대상으로 실시하였고 다음과 같은 결론은 도출 하였다. 1. 지르기 동작 수행시간 : 각 유형(Type)별 주춤서기 자세에서 주먹 지르기 동작 수행시간은 1구간에서 $0.24{\pm}0.07s$와 $0.42{\pm}0.08s$로 유형(Type)1의 주먹 지르기 동작 수행시간이 빠르게 나타났지만 전체 수행시간에 대한 구간별 비율은 유형(Type)2의 테이크 백(take back)이 더 짧은 것으로 나타났다. 2. 선속도 및 선가속도 변인 : 각 유형(Type)의 국면별 선속도는 모두 다르지만 가장 높은 선속도는 각 유형(Type)의 임팩트 순간 이라 할 수 있으며, 유형(Type)2의 임팩트 순간인 3국면에서 가장 높은 선속도가 나타났다. 3. 관절각 변인 : 유형(Type)별 주먹 지르기 동작이 관절의 각은 임팩트 국면인 유형(Type)1의 주먹 지르기 동작과 유형(Type)2의 주먹 지르기 동작에서 외형적으로 큰 차이가 나지 않지만 유형 (Type)2의 주먹 지르기 동작이 관절각의 변화가 다양해 역동적인 자세를 취하고 있다. 4. 각속도 및 각가속도 변인 : 유형(Type)1의 주먹 지르기 동작이 임팩트 순간인 3국면의 고관절, 견관절, 손목관절 의 각속도는 각각 $0.79{\pm}0.02deg/s$, $0.91{\pm}0.04deg/s$, $5.24{\pm}0.09deg/s$ 로 나타났으며, 유형(Type)2의 주먹 지르기 동작이 임팩트 순간인 4국면의 고관절, 견관절, 손목관절의 각속도는 각각 $1.32{\pm}0.03deg/s$, $0.21{\pm}0.03deg/s$, $4.98{\pm}0.08deg/s$로 나타났다. 유형(Type)2의 임팩트 순간인 3국면의 오른쪽 손목관절의 각가속도의 변화를 보면 $176.24{\pm}1.11deg/s^2$로 유형(Type)1의 임팩트 순간의 각가속도 보다 더 큰 속도의 변화를 보였다.

• 한국운동역학회지
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• 제15권4호
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• pp.55-66
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• 2005

The present study used a video analysis system to quantify the kinematical data of step shoot motion by male university handball players. From the results of analyzing dynamic variables of step shoot motion according to shooting direction were drawn conclusions as follows. 1. The height of release was proportional to the height of players, and the height of release appeared low in left-side attacks. This is probably because the left-right-throwing angle is larger in left-side attacks than that in center attacks and right-side attacks and, as a result, the throwing arm is lowered down in throwing. 2. The leftward inclination angle of the body was larger in order of right-side attacks > center attacks > left side attacks. 3. Players' throwing form was close to three quarter style in left-side attacks. In center and right-side attacks, the arm was somewhat more upright but still it was more three quarter style than overhand style. 4. The front-rear throwing angle at the moment of release was much higher in right-side attacks than in left-side ones. This is probably because the point of time for releasing the ball is usually late in right-side attacks and, as a result, the front-rear throwing angle becomes quite large. 5. The contribution of body parts on the ball speed was higher in order of the forearm > upper arm, hand > shoulder joint. 6. In players whose distance between the two legs at the moment of release, their body usually did not incline to the side much. Thus it is considered necessary to correct the right leg in their shooting motion. 7. According to the result of analyzing throwing form, the speed of the ball at the moment of leaving the hand was faster in right-side attacks than in left-side and center attacks.

• 한국정밀공학회지
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• 제23권4호
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• pp.75-82
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• 2006

In this paper, we propose an optimal trajectory for biped robots to move up-and-down stairs using a genetic algorithm and a computed-torque control for biped robots to be dynamically stable. First, a Real-Coded Genetic Algorithm (RCGA) which of operators are composed of reproduction, crossover and mutation is used to minimize the total energy. Constraints are divided into equalities and inequalities: Equality constraints consist of a position condition at the start and end of a step period and repeatability conditions related to each joint angle and angular velocity. Inequality constraints include collision avoidance conditions of a swing leg at the face and edge of a stair, knee joint conditions with respect to the avoidance of the kinematic singularity, and the zero moment point condition with respect to the stability into the going direction. In order to approximate a gait, each joint angle trajectory is defined as a 4-th order polynomial of which coefficients are chromosomes. The effectiveness of the proposed optimal trajectory is shown in computer simulations with a 6-dof biped robot that consists of seven links in the sagittal plane. The trajectory is more efficient than that generated by the modified GCIPM. And various trajectories generated by the proposed GA method are analyzed in a viewpoint of the consumption energy: walking on even ground, ascending stairs, and descending stairs.

• 한국정밀공학회지
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• 제21권11호
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• pp.209-218
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• 2004

The purpose of this paper is to suggest a practical and simple method for the identification of the joint mechanical properties and to apply it to human knee joints. The passive moment at a joint was modeled by three mechanical parts, that is, a gravity term, a linear damper term and a nonlinear spring term. Passive pendulum tests were performed in 5 fat and 5 thin men. The data of pendulum test were used to identify the mechanical properties of joints through sequential quadratic programming (SQP) with random initial values. The identification was successful where the normalized root-mean-squared (RMS) errors between the simulated and experimental joint angle trajectories were less than 10％. The parameter values of mechanical properties obtained in this study agreed with literature. The inertia, gravity and the damping constant were greater at fat men, which indicates more resistance to body movement and more energy consumption fer fat men. The suggested method is noninvasive and requires simple setup and short measurement time. It is expected to be useful in the evaluation of joint pathologies.

• 대한물리치료과학회지
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• 제7권2호
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• pp.579-595
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• 2000

The purposes of this study were to compare pelvic tilt before and after manipulation of sacroiliac joint in 31 low back pain patients (11 males, 20 females) with sacroiliac joint dysfunction. The sacroiliac joint of patients was manipulated on the side of anterior pelvic tilt, using the technique described by Stoddard (1962) and Greenmann (1996). I used this technique because it usually eliminated sacroiliac joint dysfunction in one treatment session. SPSS for window computer system was used to analyze the data. Also t-test was performed for comparison of pelvic tilt angle before and after manipulation, and Pearson product-moment correlation analysis was performed for intratester reliability for measurements of pelvic tilt angle before and after manipulation. The result were as follows: 1. Intratester reliability was good for measures of pelvic tilt (r=.98). 2. The pelvic tilt after manipulation was significantly decreased (mean=$3.40^{\circ}$) compared with the pelvic tilt before manipulation (p=.001). All subjects showed asymmetrical right versus left pelvic tilt before manipulation. 40% of subjects showed decreased asymmetrical right versus left pelvic tilt after manipulation, and 60% of subjects showed symmetrical right versus left pelvic tilt after manipulation. I think that pelvic tilt asymmetry with hypomobility due to loss of joint play could be symmetrized by manipulation or mobilization, but pelvic tilt asymmetry with unilateral pelvic muscle shortening could not be symmetrized by manipulation or mobilization without relaxation and stretching of shortened muscles.

• 한국지반공학회논문집
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• 제25권10호
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• pp.17-30
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• 2009

지하에 공동을 건설하는 터널 공사의 경우 초기 응력의 집중 및 발파와 같은 시공단계에서의 과도한 에너지의 적용으로 인하여 주변 암반에 손상을 발생시킨다. 이러한 손상의 발생은 터널에 작용하는 하중 및 터널 주변 암반의 흐름조건에 상당한 영향을 끼친다. 이러한 이유로 터널 주변에 발생하는 손상구간에 대하여 다양한 연구가 수행되었다. 본 연구에서는 유사암석으로 제작된 공동이 존재하는 절리모델의 이축압축실험을 통하여 공동주변의 손상발생을 연구하였다. 절리면은 수평면과 $30^{\circ}$, $45^{\circ}$, $60^{\circ}$의 조건으로 형성되었으며, 초조강시멘트 재료를 이용하여 유사절리모델을 제작하였다. 이축압축 실험결과 공동주변에서는 절리면에 수직한 방향으로 인장균열의 발생이 관측되었으며, 균열의 진행으로 인하여 암반블록이 형성되었으며, 진행하는 인장균열이 다른 절리면에 도달하여 암반블록이 완전히 형성된 경우 탈락하는 과정을 보였다. 이러한 인장균열의 진전은 절리면의 각도에 따라 상이한데 절리면의 각도가 클수록 안정적이며 진행성의 균열 진전 양상이 관측되었다. 이러한 인장균열의 발달은 절리면으로 구성된 암편을 보로 가정 할 경우 공동의 곡률로 인한 기하학적 형상의 불규칙성으로 인하여 모멘트가 작용하는 것으로 판단된다. 이상의 실험결과를 입자요소해석 방법을 기반으로 하는 PFC 2D를 이용하여 모사하였다. 해석결과 실험에서 관측한 바와 같이 절리면 각도가 작을수록 손상대의 폭은 넓어지며 인장균열의 진행에 의한 암반블록의 형성이 관측되었다. 또한 상호작용이 발생하는 균열을 조사한 결과 수치해석에서도 절리면의 각도가 작은 조건에서 진행성의 파괴가 나타났다.