• Journal of Dental Rehabilitation and Applied Science
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• v.18 no.2
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• pp.127-144
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• 2002

There is an increasing appreciation of the vital role that biomechanics play in the performance of oral implant. The aim of this article is to provide some basic principles that will allow a clinician to formulate a biomechanically valid treatment plan. However, at this point in the history of oral implantology, the clinician should realize that we do not know enough to provide absolute biomechanical rules that will guarantee success of all implants in all situations. To examine the biomechanical questions, one must begin with an analysis of the distribution of biting forcess to implants. Related topics, such as stress transfer to surrounding tissues and interrelationships between bone biology and mechanical loading are major subjects, deserving a separate discussion. Once rigid fixation, angulation, crestal bone level, contour, and gingival health are achieved, stress beyond physiologic limits is the primary cause of initial bone loss around implants. The restoring dentist has specific responsibilities to reduce overload to the bone-implant interface. These include proper diagnosis, leading to a treatment plan designed with adequate retention and form, and progressive loading to improve the amount and density of bone and further reduce the risk of stress beyond physiologic limits. The major remaining factor is the development of occlusal concept in harmony with the rest of the stomagnetic system.

• Journal of the Korean Society of Physical Medicine
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• v.6 no.2
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• pp.145-151
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• 2011

Purpose: The study was designed to investigate the effects of landing heights on muscle activities and ground reaction force during drop landing. Methods: Sixteen healthy adults were recruited along with their written informed consent. They performed a drop-landing task at the height of 20, 40, and 60cm. They completed three trials in each condition and biomechanical changes were measured. The data collected by each way of landing task and analyzed by One-way ANOVA. Ground reaction forces were measured by force flate, muscle activities measured by MP150 system. Results: There were significant differences in ground reaction forces, and significant increases in muscle activities of tibialis anterior, medial gastrocnemius and biceps femoris with landing heights. Conclusion: These findings revealed that heights of landing increases risk factors of body damage because of biomechanical mechanism and future studies should focus on prevention from damage of external conditions.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.23 no.60
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• pp.37-46
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• 2000

A biomechanical model of lower extremity in seated postures was developed to assess muscular activities of lower extremity involved in a variety of foot pedal operations. The model incorporated four rigid body segments with the twenty-four muscles to represent lower extremity This study deals with quasi-static movement to investigate dynamic movement effect in seated foot operation. It is found that optimization method which has been used for modeling the articulated body segments does not predict the forces generated from biarticular muscles and antagonistic muscles reasonably. So, the revised nonlinear optimization scheme was employed to consider the synergistic effects of biarticular muscles and the antagonistic muscle effects from the stabilization of the joint. For the model validation, three male subjects performed the experiments in which EMG activities of the nine lower extremity muscles were measured. Predicted muscle forces were compared with the corresponding EMG amplitudes and it showed no statistical difference. For the selection of optimal seated posture, a physiological meaningful criterion was developed for muscular load sharing developed. For exertion levels, the transition point of type F motor unit of each muscle is inferred by analyzing the electromyogram at the seated postures. Also, for predetermined seated foot operations exertion levels, the recruitment pattern is identified in the continuous exertion, by analyzing the electromyogram changes due to the accumulated muscle fatigue.

• Physical Therapy Korea
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• v.12 no.4
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• pp.33-40
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• 2005

The purpose of this study was to define more precisely the anatomy of the thumb flexor pulley system and to determine the relative contribution of each of the pulleys to the biomechanics of thumb motion at the metacarpophalangeal (MP) and interphalangeal (IP) joints. For this, 22 hands from 11 cadavers were used and randomly assigned to two groups. In the first group, the first annular (A1) pulley was cut first followed by the variable annular (Av) pulley and then the oblique pulley. In the second group, the oblique pulley was cut first followed by the, pulley and then the Av pulley. In 7 of 22 hands, it was a transverse structure parallel to the, pulley with a gap between the A1 and Av pulleys, referred to here as type I. In 9 hands, the A1 and Av pulleys were connected without any gap (type II). In 6 hands, the space between the A1 and Av pulleys were triangular in shape with fibers of the Av pulley converging toward the radial side (type III). In biomechanical study of both first and second experiments, there was no significant difference in MCP joint flexion between the all intact, A1 section, A1/Av section, A2 intact (A1/Av/oblique section), and no pulley configuration (p>.05). In occurring displacements less than 10 mm, there was no significant difference in IP joint flexion (p>.05). However, there was a significant decrease in IP joint flexion occurred in both 15 mm and 20 mm excursion (p<.05), when the oblique pulley was resected additionally after cutting the A1 and Av pulleys in first experiment, and when the A1 pulley was resected additionally after cutting the oblique pulley. According to the results, the injury of only the oblique pulley does not decrease thumb motion significantly. The oblique pulley injury with both the A1 and Av pulleys laceration decreased thumb motion significantly. The additional laceration of the A2 pulley does not decrease thumb motion.

• Korean Journal of Applied Biomechanics
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• v.25 no.1
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• pp.103-111
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• 2015

Objective : The purpose of this study was to evaluate the effect for running shoes with resilience of midsole on biomechanical properties. Methods : 10 healthy males who had no history of injury in the lower extremity with an average age of 26.5 year(SD=1.84), height of 172.22 cm(SD=4.44) and weight of 67.51 kg(SD=6.17) participated in this study. All subjects ran on the treadmill wearing three different running shoes. Foot pressure data was collected using Pedar-X system(Novel Gmbh, Germany) operating at 100 Hz. Surface EMG signals for biceps femoris, rectus femoris, vastus lateralis, medial lateralis, tibialis anterior, medial gastrocnemius, soleus and peroneus longus were acquired at 1000 Hz using Bignoli 8 System(Delsys Inc., USA). To normalize the difference of the magnitude of muscle contractions, it was expressed as a percentage relative to the maximum voluntary contraction (MVC). The impact resilience of the midsole data was collected using Fastcam SA5 system(Photron Inc., USA). Collected data was analyzed using One-way ANOVA in order to investigate the effects of each running shoes. Results : TPU midsole was significantly wider in contact area than EVA, TPE midsole in midfoot and higher in EMG activity than EVA midsole at biceps femoris. TPE midsole was significantly wider in contact area than EVA midsole in rearfoot and higher in peak pressure than EVA midsole in forefoot. EVA midsole was significantly higher in EMG activity than TPU midsole at tibia anterior. In medial resilience of midsoles, TPE midsole was significantly higher than EVA, TPU midsole. Conclusion : TPU midsole can reduce the load on the midfoot effectively and activate tibialis anterior, biceps femoris to give help to running.

• Journal of Korean Institute of Industrial Engineers
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• v.26 no.1
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• pp.73-80
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• 2000

To determine the exact direction and location of the human joint in motion is crucial in developing a more accurate human model and producing a more fitting artificial joint. There have been several reports on the biomechanical analysis of the joint to determine the anatomy and movement of joints. However, all the previous researches were made in vitro study, that is, they investigated the passive movement of the joint from cadavers and the suggested location of the joint axis was difficult to make practical applications due to the lack of the direction of joint axis. Also, in many biomechanical models, each joint axis is assumed to lie horizontally or vertically to the adjacent links. Such an assumption causes inherent inaccuracy. In this study, the direction and location of the transverse elbow axis was obtained with respect to the global coordinate system whose origin is on the lateral epicondyle of the humerus. The suggested result based on the global coordinate system lying on the external landmark will be helpful to understand the information of the axis and to make an application. From the experiments conducted for five subjects, the direction and location of the elbow transverse joint was determined for each subject by the helical axis method. A statistical validation was also performed to confirm the result. Finally, the result was applied to develop a simple elbow model which is a part of the kinematic arm model. The simple elbow movement model was developed to validate the significance of the result and the kinematic arm model was able to describe the geometry of any complex linkage system. As a result, the errors incurred from the proposed model were significantly reduced when compared to the ones from the previous approach.

• Journal of Biomedical Engineering Research
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• v.29 no.2
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• pp.132-138
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• 2008

We investigated the biomechanical properties of a newly designed self-expansion type anterior cruciate ligament (ACL) anchor. The ACL anchor consists of the ring section giving the elastic force, the wedge for maintaining in contact with the femur tunnel wall and the link suspending hamstring graft or artificial ligament. The main design parameters that determine the performance of this device were the expansion angle (${\theta}$) and the thickness ($t_R$). The Ti6Al4V anchors were heated after inserting in a jig for 1 hour at $800^{\circ}C$ in a protective argon gas atmosphere and allowed to cool to room temperature in the furnace. In order to investigate the influence of the expansion angle and the thickness of the ring on the biomechanical properties of the anchor, the maximum pull-out load, stiffness and slippage of the ACL anchor were measured using the pull-out tester, and statistical analyses were also executed. The present results showed that the design parameters gave a significant effect on the performance of the self- expansion type of anchor. The pull-out load of the ACL anchors significantly increased as the thickness of the ring section was increased, having a similar trend for both expansion angles. The ACL anchor showed about 2.5 times higher values of the pull-out load than that of the minimum load (500N)required for the "accelerated rehabilitation". The optimum ${\theta}$ and $t_R$ values of this ACL anchor were suggested to have sufficient resistance against the pull-out force, high stiffness and relatively low slippage after ACL reconstruction.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.20 no.43
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• pp.197-204
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• 1997

Torques on each joint, the compression on L5/S1 disc, the force on hand of a rider are estimated using a static biomechnic model. Forces that the rider applies to the pedals, saddle and handle during starting and speeding are estimated using static mechanics. Physical stress is considered accroding to handle height and horizontal distance between handle and pedal. When handle height is higher in normal speeding, the force on handle and sum of torques on each joint decreases.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.14 no.24
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• pp.71-81
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• 1991

인체의 운동은 많은 수의 자유도를 지닌 조인트(JOINT)와 링(LINK)의 복잡한 운동으로 표현될 수 있다. 이들 링크(LINK)의 회전 운동은 SINE, COSINE 자승 형태의 비선형 운동으로 이루어져있으나, 최근 PERSONAL COMPUTER의 발달로 복잡한 인체 운동의 수학적 모델에 대한 동력학적 DATA 계산이 가능해졌다. 본 연구에서는 5개의 링크(LINK)로 연결된 인체 움직임에 있어 링크(LINK)의 절대 운동(ABSOLUTE MOTION) 및 상대운동(RELATIVE MOTION)을 고려한 PLAGENHOEF의 운동 모델을 PERSONAL COMPUTER를 이용하여 인체 움직임의 동력학적 DATA를 얻을 수 있도록 BASIC 언어로 프로그램을 제기하였다.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.14 no.23
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• pp.7-18
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• 1991

인체의 운동은 많은 수의 자유도를 지닌 조인트(JOINT)와 링(LINK)의 복잡한 운동으로 표현될 수 있다. 이들 링크(LINK)의 회전 운동은 SINE, COSINE 자승 형태의 비선형 운동으로 이루어져있으나, 최근 PERSONAL COMPUTER의 발달로 복잡한 인체 운동의 수학적 모델에 대한 동력학적 DATA 계산이 가능해졌다. 본 연구에서는 5개의 링크(LINK)로 연결된 인체 움직임에 있어 링크(LINK)의 절대 운동(ABSOLUTE MOTION) 및 상대운동(RELATIVE MOTION)을 고려한 PLAGENHOEF의 운동 모델을 PERSONAL COMPUTER를 이용하여 인체 움직임의 동력학적 DATA를 얻을 수 있도록 BASIC 언어로 프로그램을 제기하였다.