• The Korean Journal of Applied Statistics
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• v.26 no.6
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• pp.873-887
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• 2013

The axis of rotation in biomechanics is a major tool to investigate joint function; therefore, many methods to estimate the axis of rotation have been developed. However, there exist several problems to describe, estimate, and test the axis statistically. The axis is directional data(axial data) and it should not be analyzed with traditional statistics. A proper comparative method should be considered to compare axis estimating methods for the same given data ANOVA (analysis of variance) is a frequently used statistical method to compare treatment means in experimental designs. In case of the axial data response assumed to come from Watson distribution, there are a few ANOVA method options. This study constructed ANOVA models for within-subjects designs of axial data. Two models (one within-subjects factor and two within-subjects factors crossed design) were considered. The empirical data used in this study were instantaneous axes of rotation of flexion/extension at the knee joint and the flexion/extension and pronation/supination at the elbow joint. The results of this study can be further applied to the various analysis of experimental designs.

• Journal of Biomedical Engineering Research
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• v.32 no.3
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• pp.230-236
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• 2011

The aim of this study was to investigate the alteration of lumbar spine and trunk postures on different load-carrying types and amounts under static loading. Two load-carrying types(unilateral carrying: UC vs. bilateral carrying: BC) and four different loads(0, 5, 10, and 15 kg) were randomly tested in this study. Carrying a heavy bag would affect human body posture, specifically lumbar spine curvature, which is considered as one of sources of back problems. Previous studies have not paid attention to the approach of the multisegment model of the lumbar spine and trunk. This study separated two compartments of trunk segment(the lumbar and thorax) in the analysis. The multisegment model of the lumbar spine in addition to Helen-Hayes marker set was used. Eight motion analysis cameras and a force plate were utilized. Ten male subjects(mean mass, $70.6{\pm}3.97$ kg; mean height, $178{\pm}4.18$ m) having no musculoskeletal disease participated in this study. We analyzed trunk angles in three anatomical planes and the spinal curvature in sagittal and frontal planes. Increased loading in both UC and BC significantly resulted in increases in trunk forward lean but only UC induced increases in trunk lateral lean. In addition, increased loading in BC produced flatten lumbar curvature in sagittal plane. As far as coupling motion, subjects tended to use axial rotation of the lumbar spine in transverse plane in response to increased UC loading. Finally, it is concluded that the increased static loading in UC rather than in BC tends to causes combined alterations of the spinal postures(sagittal and transverse planes together), which would be vulnerable to improper mechanical stresses on the spine.

• The Journal of Korean Orthopaedic Ultrasound Society
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• v.1 no.2
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• pp.112-116
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• 2008

Ultrasonography of shoulder joint recently enlarges its utility since the knowledge of the shoulder disease is increased by numerous researches. Ultrasonography is not only noninvasive, safe, and relatively cheap, but also an unique modality that can monitor tendon movement during shoulder motion. Sonographic examination generally starts from the front side of the shoulder joint and finishes at back side in sitting position. Many structures in shoulder joint such as muscles, ligaments, glenoid labrum, bone, and especially rotator cuff tendon can be examined by ultrasonography. The rotator cuff is a motion unit consisted with subscapularis, supraspinatus, infraspinatus, and teres minor muscles. It functions as fulcrum and compresses the humeral head onto the glenoid, and steers for shoulder joint.

• The Journal of the Korea Contents Association
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• v.16 no.12
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• pp.327-345
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• 2016

The purpose of this study was to carry out cognitive movement therapy program for children with affective and behavioral disorder based on neuro science, psychology, motor learning, muscle physiology, biomechanics, human motion analysis, movement control and to quantify characteristic of expression and gestures according to change of facial expression by emotional change. We could observe problematic expression of children with affective disorder, and could estimate the efficiency of application of movement therapy program by the face expression change of children with affective disorder. And it could be expected to accumulate data for early detection and therapy process of development disorder applying converged measurement and analytic method for human development by quantification of emotion and behavior therapy analysis, kinematic analysis. Therefore, the result of this study could be extendedly applied to the disabled, the elderly and the sick as well as children.

• Journal of Institute of Control, Robotics and Systems
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• v.17 no.10
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• pp.1021-1028
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• 2011

The objective of this paper is to optimize the design parameters of a novel mechanism for a robotic knee orthosis. The feature of the proposed knee othosis is to drive a knee joint with independent actuation during swing and stance phases, which can allow an actuator with fast rotation to control swing motions and an actuator with high torque to control stance motions, respectively. The quadriceps device operates in five-bar links with 2-DOF motions during swing phase and is changed to six-bar links during stance phase by the contact motion to the patella device. The hamstring device operates in a slider-crank mechanism for entire gait cycle. The suggested kinematic model will allow a robotic knee orthosis to use compact and light actuators with full support during walking. However, the proposed orthosis must use additional linkages than a simple four-bar mechanism. To maximize the benefit of reducing the actuators power by using the developed kinematic design, it is necessary to minimize total weight of the device, while keeping necessary actuator performances of torques and angular velocities for support. In this paper, we use a SGA (Simple Genetic Algorithm) to minimize sum of total link lengths and motor power by reducing the weight of the novel knee orthosis. To find feasible parameters, kinematic constraints of the hamstring and quadriceps mechanisms have been applied to the algorithm. The proposed optimization scheme could reduce sum of total link lengths to half of the initial value. The proposed optimization scheme can be applied to reduce total weight of general multi-linkages while keeping necessary actuator specifications.

• The Journal of Advanced Prosthodontics
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• v.12 no.2
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• pp.67-74
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• 2020

PURPOSE. This study evaluated the influence of prosthesis weight and number of implants on the bone tissue microstrain. MATERIALS AND METHODS. Fifteen (15) fixed full-arch implant-supported prosthesis designs were created using a modeling software with different numbers of implants (4, 6, or 8) and prosthesis weights (10, 15, 20, 40, or 60 g). Each solid was imported to the computer aided engineering software and tetrahedral elements formed the mesh. The material properties were assigned to each solid with isotropic and homogeneous behavior. The friction coefficient was set as 0.3 between all the metallic interfaces, 0.65 for the cortical bone-implant interface, and 0.77 for the cancellous bone-implant interface. The standard earth gravity was defined along the Z-axis and the bone was fixed. The resulting equivalent strain was assumed as failure criteria. RESULTS. The prosthesis weight was related to the bone strain. The more implants installed, the less the amount of strain generated in the bone. The most critical situation was the use of a 60 g prosthesis supported by 4 implants with the largest calculated magnitude of 39.9 mm/mm, thereby suggesting that there was no group able to induce bone remodeling simply due to the prosthesis weight. CONCLUSION. Heavier prostheses under the effect of gravity force are related to more strain being generated around the implants. Installing more implants to support the prosthesis enables attenuating the effects observed in the bone. The simulated prostheses were not able to generate harmful values of peri-implant bone strain.

• Biomaterials and Biomechanics in Bioengineering
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• v.2 no.1
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• pp.47-59
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• 2015

A bioactive and multifunctional elastin-like polymer (ELP) was produced by genetic engineering techniques to develop new artificial matrices with the ability to mimic the extracellular matrix (ECM). The basic composition of this ELP is a thermo- and pH-sensitive elastin pentapeptide which has been enriched with RGD-containing domains, the RGD loop of fibronectin, for recognition by integrin receptors on their sequence to promote efficient cell attachment. Hydrogels of this RGD-containing polymer were obtained by crosslinking with hexamethylene diisocyanate, a lysine-targeted crosslinker. These materials retain the "smart" nature and temperature-responsive character, and the desired mechanical behavior of the elastin-like polymer family. The influence of the degree of crosslinking on the morphology and properties of the matrices were tested by calorimetric techniques and scanning electron microscopy (SEM). Their mechanical behavior was studied by dynamical mechanical analysis (DMA). These results show the potential of these materials in biomedical applications, especially in the development of smart systems for tissue engineering.

• Biomaterials and Biomechanics in Bioengineering
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• v.2 no.1
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• pp.23-32
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• 2015

Facile immobilization of growth factors in hyaluronic acid (HA) hydrogels using dual enzymes is reported in the paper. The hydrogels were formed by using horseradish peroxidase (HRP) and hydrogen peroxide ($H_2O_2$) and transforming growth factor-${\beta}3$ (TGF-${\beta}3$) was covalently conjugated on the hydrogels in situ using tyrosinase (Ty) without any modifications. For the preparation of hydrogels, HA was grafted with poly(ethylene glycol) (PEG), which was modified with a tyrosine. The gelation times of the HA hydrogels were ranging from 415 to 17 s and the storage moduli was dependent on the concentration of $H_2O_2$ and Ty (470-1600 Pa). A native TGF-${\beta}3$ (200 ng/mL) was readily encapsulated in the HA hydrogels and 17% of the TGF-${\beta}3$ was released over 1 month at the Ty concentration of 0.5 KU/mL, while the release was faster when 0.3 KU/mL of Ty was used for the encapsulation (27%). It can be suggested that the growth factors resident in the hydrogels for a long period of time may lead cells proliferating and differentiating, whereas the growth factors that are initially released from the hydrogels can induce the ingrowth of cells into the matrices. Therefore, the dual enzymatic methods as facile gel forming and loading of various native growth factors or therapeutic proteins could be highly promising for tissue regenerative medicines.

• Journal of rehabilitation welfare engineering & assistive technology
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• v.7 no.1
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• pp.21-27
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• 2013

Manual wheelchair propulsion can lead to pain and injuries of users due to mechanical inefficiency of wheelchair propulsion motion. The kinetic analysis of the upper limbs during manual wheelchair propulsion needs to be studied. A two dimensional inverse dynamic model of upper limbs was developed to compute the joint torque during manual wheelchair propulsion. The model was composed of three segments corresponding to upper arm, lower arm and hand. These segments connected in series by revolute joints constitute open chain mechanism in sagittal plane. The inverse dynamic method is based on Newton-Euler formalism. The model was applied to data collected in experiments. Kinematic data of upper limbs during wheelchair propulsion were obtained from three dimensional trajectories of markers collected by a motion capture system. Kinetic data as external forces applied on the hand were obtained from a dynamometer. The joint rotation angles and joint torques were computed using the inverse dynamic model. The developed model is for upper limbs biomechanics and can easily be extended to three dimensional dynamic model.

• Journal of Korean Medicine Rehabilitation
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• v.20 no.3
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• pp.75-91
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• 2010

Objectives : Although the controversy surrounding the biomechanics of the sacroiliac joint remains unresolved at this time, the clinical importance of this joint in the cause of back pain has been established since 1930's. Recently, there has been renewed interest in the sacroiliac joint. This study was performed to evaluate the effects of pulsed electromagnetic therapy(PEMT) with acupuncture therapy for patients, who were suffering from sacroiliac joint syndrome, and to conduct more researches in the usage of acupuncture therapy for treating sacroiliac joint syndrome. Methods : 25 patients, who were diagnosed as sacroiliac joint syndrome were selected. They were treated twice a week during 3 weeks. They were measured after all the treatment and firs week and fourth week after termination of treatment by using visual analogue scale(VAS) and Roland Morris disability index(RMDI). The VAS and RMDI patterns were analyzed by using 'pared T-test' and 'Kruskal-Wallis' test. Results : 1. Each times of PEMT with acupuncture therapy, there were statistical significance in improvement of VAS(p<0.05) and each times of therapy except 1st one, there were statistical significance in improvement of RMDI(p<0.05). 2. After 4th therapy, there were most significant improvement of VAS with RMDI(p<0.001), when we compared the change in VAS and RMDI before and after the each therapy. 3. There was no statistical significance in VAS and RMDI by onset, sex and age. Conclusions : The results indicate that pulsed electromagnetic therapy and acupuncture therapy had good effect on sacroiliac joint syndrome.