• Advances in biomechanics and applications
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• v.1 no.3
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• pp.169-185
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• 2014

Computational multibody models of the elbow can provide a versatile tool to study joint mechanics, cartilage loading, ligament function and the effects of joint trauma and orthopaedic repair. An efficiently developed computational model can assist surgeons and other investigators in the design and evaluation of treatments for elbow injuries, and contribute to improvements in patient care. The purpose of this study was to develop an anatomically correct elbow joint model and validate the model against experimental data. The elbow model was constrained by multiple bundles of non-linear ligaments, three-dimensional deformable contacts between articulating geometries, and applied external loads. The developed anatomical computational models of the joint can then be incorporated into neuro-musculoskeletal models within a multibody framework. In the approach presented here, volume images of two cadaver elbows were generated by computed tomography (CT) and one elbow by magnetic resonance imaging (MRI) to construct the three-dimensional bone geometries for the model. The ligaments and triceps tendon were represented with non-linear spring-damper elements as a function of stiffness, ligament length and ligament zero-load length. Articular cartilage was represented as uniform thickness solids that allowed prediction of compliant contact forces. As a final step, the subject specific model was validated by comparing predicted kinematics and triceps tendon forces to experimentally obtained data of the identically loaded cadaver elbow. The maximum root mean square (RMS) error between the predicted and measured kinematics during the complete testing cycle was 4.9 mm medial-lateral translational of the radius relative to the humerus (for Specimen 2 in this study) and 5.30 internal-external rotation of the radius relative to the humerus (for Specimen 3 in this study). The maximum RMS error for triceps tendon force was 7.6 N (for Specimen 3).

• Journal of the Korean Society for Nondestructive Testing
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• v.31 no.5
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• pp.494-499
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• 2011

This paper presents the biomechanical analysis and evaluation technology of musculoskeletal system by multi-body human dynamic model and 3-D motion capture data. First, medical image based geometric model and material properties of tissue were used to develop the human dynamic model and 3-D motion capture data based motion analysis techniques were develop to quantify the in-vivo joint kinematics, joint moment, joint force, and muscle force. Walking and push-up motion was investigated using the developed model. The present model and technologies would be useful to apply the biomechanical analysis and evaluation of human activities.

• Journal of the Ergonomics Society of Korea
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• v.26 no.2
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• pp.45-59
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• 2007

The operating tasks of overhead crane have caused undue stress to the operators from physical, mental, and environmental workload. Existing workload assessment models for musculoskeletal disorders such as OWAS, RULA, and QEC have limited applicability to the crane operating tasks because they focus mainly on physical factors and do not consider the relative importance of each factor. The present study was to develop a workload assessment model customized to overhead crane operation, following a systematic process: (1) analyzing task characteristics, (2) selecting workload factors, (3) developing assessment methods, (4) establishing action levels, and (5) computerizing the assessment model. Based on literature review, worksite survey, and focus group interview, 4 physical factors (awkward posture, static posture, repetitive motion, and excessive force), 6 mental factors (visual demand, auditory demand, task complexity and difficulty, time urgency, work schedule related stress, and safety related stress), and 4 environmental factors (noise, vibration, dust, and temperature) were selected and their rating scales and relative weights were determined. Then, based on the workload assessment results of 8 overhead cranes operated at different workplaces, the action levels of each factor category were established. Finally, the crane operation assessment model was computerized for effective analysis and report preparation. The present approach is applicable to develop a customized workload assessment model for an operating task under consideration.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.8
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• pp.691-701
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• 2017

The barbell squat is a fundamental physical exercise for strengthening the lower body and core muscles. It is an integral part of training and conditioning programs in sports, rehabilitation, and fitness. In this paper, we proposed a virtual test framework for squat exercises using a Smith machine to simulate joint torques and muscle forces, based on an integrated product-human model and motion synthesis algorithms. We built a muscular skeletal human model with boundary conditions modeling the interactions between the human body and a machine or the ground. To validate the model, EMG, external forces, and squat motions were captured through physical experiments by varying the foot position. A regression-based motion synthesis algorithm was developed based on the captured squat motions to generate a new motion for a given foot position. The proposed approach is expected to reduce the need for physical experiments in the development of training programs.

• Physical Therapy Korea
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• v.11 no.4
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• pp.51-60
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• 2004

Falls are common, costly, and a leading cause of death among older adults. The major predisposing factors of a fall may include age-related deterioration in the dynamic system composed of auditory, somatosensory, vestibular, visual, musculoskeletal, and neuromuscular subsystems. Older adults with a history of frequent falls demonstrated significant reductions in gait velocity, muscle force production, and balance performance. These altered neuromechanical characteristics may be further exaggerated when faced with conflicting multisensory conditions. Despite the important contribution of multisensory function on the sensorimotor system during postural and locomotor tasks, it remains unclear whether multisensory intervention will produce dynamic balance improvement during locomotion in older adults with a history of frequent falls. Therefore, the purpose of this paper is to address important factors associated with falls in elderly adults and provide theoretical rationale for a multisensory intervention program model.

• Transactions of the Korean Society of Automotive Engineers
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• v.15 no.6
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• pp.62-72
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• 2007

Fracture analysis of human bone is necessary to predict the failure of musculoskeletal structures and to heal them by several possible mechanisms under different loading conditions. But human bone is a complex material, with a multiphase, heterogeneous and anisotropic microstructure. Due to the difficulty of obtaining experimental and clinical results, the importance of numerical analysis and computational simulations in biomechanics are increasing gradually. In this study, stress analysis for human femur model is performed by using the 2-dimensional finite element method(FEM) and its stress distribution is determined. From these results, the fracture mechanic parameters are calculated and the fracture criteria on human femur are investigated and discussed.

• Journal of the Ergonomics Society of Korea
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• v.29 no.5
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• pp.819-829
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• 2010

By referring thirty-seven previous studies on manual material handling (MMH), this paper analyzed guidelines and main factors of one-handed tasks. The previous studies concerned main factors of distance, weight, frequency, posture, gender, age, training, direction of force, height of the force exerted, and object shape and size. Based on these factors, the criteria used to understand one-handed tasks were objective measures of maximum strength, reaction force, etc., psychophysical measures of maximum acceptable frequency and weight, etc., and physiological measures of oxygen uptake, heart rate, electromyography, etc. An allowance threshold model regarding quantitative and objective fatigue and workload would be suggested for future research. This study would be expected that it serve to establish and Korean recommendations of one-handed tasks.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.359-363
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• 2004

Numerous studies have been performed to analyze various phenomena of human's walking, gait. In the present study, unrecognized walking and recognized walking were analyzed by three dimensional motion capture system(VICON motion system Ltd., England) and simulated by computer program. Two normal males participated in measuring the motion of unrecognized and recognized walking. Six infrared cameras and four force plates were used and sixteen reflective markers were attached to the subject to capture the motion. A musculoskeletal model was generated anatomically by using ADAMS(MSC software corp., USA) and LifeMOD(Biomechanics Research Group Inc, USA). The inverse dynamic simulation and forward dynamic simulation were also performed. The result of simulation was similar to the experimental result. This study provides the base line for dynamic simulation of the falling walking. It will be useful to simulate various another pathologic gaits for old peoples.

• Journal of the Ergonomics Society of Korea
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• v.29 no.4
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• pp.445-453
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• 2010

It is necessary to quantitatively evaluate the workload of workers in order to improve the level of safety and efficiency as well as to prevent workers from musculoskeletal disorders. The purpose of this study is to introduce biomechanical methods that are largely used to quantitatively evaluate workload. The biomechanical methods use kinematics and kinetics to analyze the movement and force of biomechanical body. Motion analysis, joint angle measurement, ground reaction force, mathematical model, and electromyography (EMG) were introduced as a tool or device for biomechanical evaluation. In this study, the special feature of each method was emphasized and important tips for field measurement were summarized. The information and technique disclosed in this summary can be used to evaluate and design the workplace better by effectively control the workload of field workers.

• Clinics in Shoulder and Elbow
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• v.6 no.2
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• pp.115-126
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• 2003

Although painful conditions of varying degrees of severity involving the soft tissues (i .e., muscles, tendons, ligaments, periosteum and peripheral nerves) occur frequently, their underlying pathogenesis is poorly understood. The term peripheral neuropathic pain has recently been suggested to embrace the combination of positive and negative symptoms in patients whose pain is due to pathological changes or dysfunction in peripheral nerves or nerve root. The spinal nerve root, because of its vulnerable position, is very easily prone to injury from pressure, stretch, angulation, and friction. Therefore, not a few of musculoskeletal chronic pains are result of nerve root dysfunction. Neuropathic changes due to nerve root dysfunction are primarily in soft tissue especially muscle, tendon and joint. It shows tenderness over muscle motor points and palpable muscle contracture bands and restricted Joint range. Careful palpation and physical examination is the important tool that, be abne to detect all of these phenomena.