• The Journal of Korean Physical Therapy
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• 제31권6호
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• pp.333-338
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• 2019

Purpose: Although previous studies on the screw-home movement (SHM) for autopsy specimen and walking of living persons conducted, the possibility of acquiring SHM based on inertial measurement units received little attention. This study aimed to investigate the possibility of measuring SHM for the non-weighted bearing using a micro-electro-mechanical system-based wearable motion capture system (MEMSS). Methods: MEMSS and camera-based motion analysis systems were used to obtain kinematic data of the knee joint. The knee joint moved from the flexion position to a fully extended position and then back to the start point. The coefficient of multiple correlation and the difference in the range of motion were used to assess the waveform similarity in the movement measured by two measurement systems. Results: The waveform similarity in the sagittal plane was excellent and the in the transverse plane was good. Significant differences were found in the sagittal plane between the two systems (p<0.05). However, there was no significant difference in the transverse plane between the two systems (p>0.05). Conclusion: The SHM during the passive motion without muscle contraction in the non-weighted bearing appeared in the entire range. We thought that the MEMSS could be easily applied to the acquisition of biomechanical data on the knee related to physical therapy.

• 한국운동역학회지
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• 제26권3호
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• pp.243-248
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• 2016

Objective: The aim of this study was to determine the kinematical characteristics of somersault with twist in the Lou Yun and Akopian motions and to provide useful information to gymnastic athletes in men's vault. Method: The study subjects were 12 male adult top athletes. After 12 trials (7 Lou Yun and 5 Akopian trials) filmed by using two digital high-speed camcorders set at 90 frames/sec, kinematical data were collected through the direct linear transformation (DLT) method. The mean differences in biomechanical variables were compared during the second flight upward phase. The kinematic characteristics of somersault with twist in the Lou Yun and Akopian motions were identified. Results: In Lou Yun motion, the vertical release velocity through horse breaking was not difficult to obtain, so the athletes had enough time to prepare for the twist. Therefore, the Lou Yun motion has an advantage to make a cat twist in the pike posture. In the Akopian motion, obtaining the horizontal velocity through horse pushing was so easy that the Akopian athletes attained a large angular impulse and angular momentum. Therefore, the Akopian motion has an advantage to making a tilt twist in the body tilting posture. Conclusion: This study suggests that gymnastic athletes should control their body segment movements in order to increase the twisting angular velocity of the whole body, which requires regulation of the longitudinal moment of inertia of the body. Moreover, athletes should prepare for the shoulder and hip twists early in order to make the landing position in advance.

• 한국운동역학회지
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• 제17권4호
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• pp.209-219
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• 2007

The purpose of this study was to analyze biomechanical mechanism (posture, moment of back joint, EMG) when athletes (Judo, Ssirum) and lay people lifted a load according to two different lift methods; backlift and leglift. The number of subjects was 12; 8 athletes (4 for Judo, 4 for Ssirum) and 4 lay people. We recorded a lift motion in backlift and leglift using 7 real time infrared cameras (vicon) and analyzed EMG pattern of major muscles for a lift (lattisimus dorsi, erector spinae, biceps femoris). In a backlift Judo players showed a biggest range of back flexion and extension motion and lay people flexed more than other groups at phase 2 in which an interaction between groups and events was statistically significant (p=.024). In a leglift Ssirum players more flexed their back in a barbell lift and there was a statistical significance (p=.021) between groups and events. For moment of back joints, 1) in a backlift a larger loading on back joints in all three groups at phase 2 when lifting down a barbell, 2) in a leglift a larger loading on back joints when lifting down a barbell in two athlete groups but a larger loading when lifting up a barbell in lay people group, and all groups did not show any statistical significance. For EMG, right lattisimus dorsi muscle in a backlift was statistical significant (p=.006) in an interaction between groups and phase but left lattisimus dorsi muscle was insignicant, and there was not any significance in a leglift. Generally atheletes (Judo and Ssirum) used more their muscles of lower extremity in lifting up and down and lay people did more their ones of upper extremity.

• Safety and Health at Work
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• 제4권2호
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• pp.105-110
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• 2013

Background: To determine the influence of lifting speed and type on peak and cumulative back compressive force (BCF) and shoulder moment (SM) loads during symmetric lifting. Another aim of the study was to compare static and dynamic lifting models. Methods: Ten male participants performed a floor-to-shoulder, floor-to-waist, and waist-to-shoulder lift at three different speeds [slow (0.34 m/s), medium (0.44 m/s), and fast (0.64 m/s)], and with two different loads [light (2.25 kg) and heavy (9 kg)]. Two-dimensional kinematics and kinetics were determined. A three-way repeated measures analysis of variance was used to calculate peak and cumulative loading of BCF and SM for light and heavy loads. Results: Peak BCF was significantly different between slow and fast lifting speeds (p < 0.001), with a mean difference of 20% between fast and slow lifts. The cumulative loading of BCF and SM was significantly different between fast and slow lifting speeds (p < 0.001), with mean differences ${\geq}80%$. Conclusion: Based on peak values, BCF is highest for fast speeds, but the BCF cumulative loading is highest for slow speeds, with the largest difference between fast and slow lifts. This may imply that a slow lifting speed is at least as hazardous as a fast lifting speed. It is important to consider the duration of lift when determining risks for back and shoulder injuries due to lifting and that peak values alone are likely not sufficient.

• 한국운동역학회지
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• 제15권4호
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• pp.143-151
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• 2005

This study was conducted to investigate the technical factors of Cuervo forward straight vaults with single twist, single and half twists, and double twists actually performed by three execellent male gymnasts participated in artistic gymnastics competition of 2003 summer Universiade in Daegu and the 85th National Sports Festival in Cheongju. To accomplish the research goals the Cuervo vaults of three gymnasts were filmed by using three digital camcorders set by 60 Hz, and data were collected through the DLT method of three dimensional cinematography. The kinematic and kinetic variables as each phasic time, CM displacement velocity, release angle inclination angle hip joint angle landing angle, average horse reaction force average moment arm average torque, whoe body's total remote local angular momentum were analyzed, so the following conclusions were reached. Generally to perform the better Cuervo vault, a gymnast should touch down on the board with the great horizontal velocity of the whole body through the fast run-up, and touch down on the horse by decreasing the horizontal displacement of the whole body during the preflight, so raise CM height gradually within a short horse contact time. He should increase the horse reaction force through checking the horizontal velocity of the whole body effectively and the inclination angular displacement of the handstand, if so he can have the large vertical velocity of the whole body. By using the acquired the velocity and the angular momentum of the whole body, he can vault himself higher and twist sufficiently, then he can get better if the body could be tilted by swinging both arms and perform the cat twist with a little flexions at hip joints. According to the above outcomes we can judge that the best athletes is LuBin, the better is YTY, and the next is JSM.

• 한국운동역학회지
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• 제17권1호
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• pp.1-8
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• 2007

Ground reaction force (GRF) measures are one of the most commonly used in biomechanical study. GRF system is very useful educational tool to explain and demonstrate the Newton's law of universal gravitation and laws of motion as well. However, accuracy, intra- and inter- force platform measures' consistency, reliability, noise, and the effect of platform mounting to GRF measures were not clearly viewed. The aim of this study was to examine the above. GRFs of a plastic dummy and two subjects' quiet upright standing were collected at four university laboratories eight force platforms. The types of platforms, analysis programs, and platform set-up were various. Three 100s-trials were conducted with sampling frequency of 100 Hz. First two trials' vertical component of GRFs, Fz, and CoP sway ranges of mid-60s-portion of 100s trials were analyzed by the paired t-tests and one-way ANOVA. Six of eight platforms' 1st and 2nd trial dummy Fz were statistically different (p<.05) and all platforms ICC were poor (<.28). Fz of the two platforms in every four laboratories were statistically different (p<.05). There were white noises and/or very distinctive noises at specific frequency ranges in all Fz measures. 5 Hz low-pass filtering made clear the Fz differences. CoP ranges of dummy were less than 0.5 cm and the best was 0.02 cm. This CoP range finding agrees with previous results suggests the importance of force platform mounting and A/D card resolution.

• Archives of Pharmacal Research
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• 제28권11호
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• pp.1311-1316
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• 2005

To better define the relationship between dermal regeneration and wound contraction and scar formation, the effects of epidermal growth factor (EGF) loaded in collagen sponge matrix on the fibroblast cell proliferation rate and the dermal mechanical strength were investigated. Collagen sponges with acid-soluble fraction of pig skin were prepared and incorporated with EGF at 0, 4, and 8 $\mu$g/1.7 $cm^{2}$. Dermal fibroblasts were cultured to 80$\%$ confluence using DMEM, treated with the samples submerged, and the cell viability was estimated using MTT assay. A deep, $2^{nd}$ degree- burn of diameter 1 cm was prepared on the rabbit ear and the tested dressings were applied twice during the 15-day, post burn period. The processes of re-epithelialization and dermal regeneration were investigated until the complete wound closure day and histological analysis was performed with H-E staining. EGF increased the fibroblast cell proliferation rate. The histology showed well developed, weave-like collagen bundles and fibroblasts in EGF-treated wounds while open wounds showed irregular collagen bundles and impaired fibroblast growth. The breaking strength (944.1 $\pm$ 35.6 vs. 411.5 $\pm$ 57.0 Fmax, $gmm^{-2}$) and skin resilience (11.3 $\pm$ 1.4 vs. 6.5 $\pm$ 0.6 mJ/$mm^{2}$) were significantly increased with EGF­treated wounds as compared with open wounds, suggesting that EGF enhanced the dermal matrix formation and improved the wound mechanical strength. In conclusion, EGF-improved dermal matrix formation is related with a lower wound contraction rate. The impaired dermal regeneration observed in the open wounds could contribute to the formation of wound contraction and scar tissue development. An extraneous supply of EGF in the collagen dressing on deep, $2^{nd}$ degree-burns enhanced the dermal matrix formation.

• 대한치과보철학회지
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• 제29권1호
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• pp.167-213
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• 1991

The successful replacement of missing teeth has been one driving aim behind the emergence of implant dentistry as both a technology and clinical vocation for over four decades. To date, a multitude of dental implant devices had been designed and utilized in the patient population. Most of these devices have been designed without support of the engineering criteria. The long-term success of any dental implant is dependent upon the optimization of stresses which occurs during oral function and parafunction. Although many studies have examined the biologic interactions between dental implants and living tissue, few studies have been reported on the biomechanical aspects of dental implants. The purpose of this study was to analyze the stress distribution of osseointegrated prosthesis on certain conditions, such as amount of load, location of load, length of fixtures, number of fixtures used, arch shape, bone quality, etc. Three dimentional finite element analysis was used for this study. FEM models were created using commercial software(Super SAP. for IBM 16 bit AT computer. All elements were 8-node brick, isoparametric. Mandible and prosthesis was modeled with 780 elements and 1074 nodes. The results were as follows : 1. In case of cantilever extension, there was a compressive stress at the base of the first implant and a tensile stress at the base of the second implant. 2. The stresses were linearly proportional to the amount of load. 3. The stresses were linearly proportional to the length of cantilever. 4. There was a stress concentration at the neck of the implant and bone under horizontal loads.

• 대한기계학회논문집B
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• 제35권11호
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• pp.1243-1248
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• 2011

본 연구에서는 한국인 표준체형과 유사한 사람의 의료 영상 자료를 이용하여 인체 골격계 모델을 만들었다. 이를 동역학 해석 상용 소프웨트어인 $RecurDyn^{TM}$에 탑재시켜 인체 시뮬레이션 모듈을 개발하였고, 노인의 보행 동작해석을 통해 모델을 검증하여 보행기(elderly walker) 사용 유무에 따른 앉기-서기 및 보행을 분석하였다. 노인이 보행기를 사용하였을 때 앉기-서기 동작 시 하지관절 기구학의 변화는 미비하였고, 보행 시 각 관절의 가동범위가 조금 줄었고 동작시간이 상당히 길어졌다. 또한 근전도 해석결과 일부 발목 주변 근육들과 햄스트링 근육에서 근활성치가 줄거나 활성시간이 줄었다. 이러한 변화는 보행기를 통해 보행할 때 하지의 기여도가 감소했기 때문이라고 생각되었다. 본 연구를 통해 얻어진 시뮬레이션 기술은 여러 가지의 생체역학 연구에 널리 활용될 것으로 생각된다.

• 대한의용생체공학회:의공학회지
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• 제25권6호
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• pp.511-517
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• 2004

기존의 재활운동 장치들은 상지 또는 하지의 특정한 관절에 대해서만 재활운동이 가능하게 개발되었다. 따라서 여러 관절을 재활시키고자 할 경우, 그에 맞는 다양한 종류의 재활기구 들이 필요하다. 이러한 단점을 보완하기 위하여 본 연구에서는 각 관절에서 이루어지는 다양한 재활운동을 통합 구현하는 CMRS(CIM and Robotics Lab. Multi - joint Rehabilitation System)을 제안하였다. 이 시스템을 위해 인체의 상지 및 하지에 대한 기구학적 특성을 이용하여 각 관절의 회전 특성 및 좌표관계를 조사하였으며, 이와 같은 연구를 바탕으로 재활운동 기구 제작 시 알맞은 메커니즘을 제시하고. 다양한 재활 부위와 이를 재활 운동시키는 헤드부의 위치관계를 연구하였다. 시뮬레이션을 통하여 재활운동 시스템의 가능성을 판별하였고. 안정되고 편리한 위치 조정을 위한 베이스프레임을 개발하였다. 이를 고려하여 최종적으로 8개의 자유도를 가진 CMRS을 개발하였으며 다 관절을 하나의 시스템으로 재활 가능할 것이라 사료 된다.