• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.19 no.6
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• pp.797-803
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• 2010

A method has been developed to tune the static stiffness at a rotation joint considering the whole machine tool system by interactive use of finite element method and experiment. This paper describes the procedure of this method and shows the results. The method uses the static experiment on measurement model which is set-up so that the effects of uncertain factors can be excluded. For FEM simulation, the rotation joint model is simplified using only spindle, bearing and spring. At the rotation joint, the damping coefficient is ignored, The spindle and bearing is connected by only spring. By static experiment, 500 N is forced to the front and behind portion of spindle and the deformation is measured by capacitive sensor. The deformation by FEM simulation is extracted with changing the static stiffness from the initial static stiffness considering only rotation joint. The tuning static stiffness is obtained by exploring the static stiffness directly trusting the deformation from the static experiment. Finally, the general tuning method of the static stiffness of machine tool joint is proposed using the force stream and the modal analysis of machine tool.

• Physical Therapy Korea
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• v.2 no.2
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• pp.46-55
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• 1995

The purpose of this study was to assess the concurrent validity and reliability of goniometric measurement of joint motion. Subjects were 40 healthy university students. Measurements were performed by 4 inexperienced physical therapy students. Four different instruments were used and three readings were taken with each instrument in random order making a total of 12 readings for flexion of the right elbow of each subject. Goniometers used were 1. universal 2. fluid-based goniometer/inclinometer 3. digital LCD goniometer 4. electronic goniometer/torsiometer. The results were as follows: Concurrent validity was highest (r= .94) with the universal and digital LCD tools. Interrater reliability (Pearson Product Moment Correlation) was good for each tool. Interrater reliability calculated by ICC(2,1) was highest (.96) with the tensiometer and lowest (.78) with the digital LCD goniometer. Intrarater reliability calculated by ICC was excellent (${\geq}.90$) for all instruments. These results show that concurrent validity, intrarater and interrater reliability are very good in the used of all four types of goniometers/inclinometer/tensiometer, even with inexperienced raters. These results confirm the almost universal reliance on hand held goniometers for joint measurement by physical therapists as being a reliable practice. Further research should be done clinically with actual patients.

• International journal of advanced smart convergence
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• v.11 no.4
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• pp.57-67
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• 2022

The demand for personal training (PT), through which high exercise effects can be achieved within short-term, has recently increased. PT can achieve an exercise amount improvement effect, only if accurate postures are maintained upon performing PT, and exercise with inaccurate postures can cause injuries. However, research is insufficient on exercise amount comparisons and judging exercise accuracy on PT. This study proposes an exercise accuracy measurement algorithm and compares differences in exercise amounts according to exercise postures through experiments using a respiratory gas analyzer. The exercise accuracy measurement algorithm acquires Euler anglesfrom major body parts operated upon exercise through a motion device, based on which the joint angles are calculated. By comparing the calculated joint angles with each reference angle in each exercise step, the status of exercise accuracy is judged. The calculated results of exercise accuracy on squats, lunges, and push-ups showed 0.02% difference in comparison with actually measured results through a goniometer. As a result of the exercise amount comparison experiment according to accurate posture through a respiratory gas analyzer, the exercise amount was higher by 45.19% on average in accurate postures. Through this, it was confirmed that maintaining accurate postures contributes to exercise amount improvement.

• Imaging Science in Dentistry
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• v.36 no.1
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• pp.41-48
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• 2006

Purpose : To evaluate the reliability and clinical usefulness of ultrasonography in the temporomandibular joint (TMJ). Materials and Methods : Parasagittal and paracoronal 1.5 T MR images and 7.5 MHz ultrasonographs of 40 TMJs in 20 asymptomatic volunteers were obtained. Disc position using MR imaging was evaluated and the distance between the lateral surface of mandibular condyle and the articular capsule using MR image and ultrasonograph of 27 TMJs with normal disc position was measured and compared. Intraobserver and interobserver measurements reliability was evaluated by using interclass correlation coefficients (ICC) and measurement error. Also, the distance measured on ultrasonographs was compared, according to mouth position and disc postion. Results : The normal disc position was found in 27 of 40 asymptomatic joints. At the intraobserver reliability of measurement, ICC at the closed and open mouth position were 0.89 and 0.91. The measurement error was 0.4% and 0.5%. At the interobserver reliability, ICC at the closed and open mouth position were 0.92 and 0.81. The measurement error was 0.4% and 0.7%. At the TMJ with normal disc position, the distances between the lateral surface of mandibular condyle and the articular capsule measured on MR images and ultrasonographs were $2.0{\pm}0.7mm,\;1.8{\pm}0.5mm$, respectively (p<0.05). On the ultrasonographs, the distances at open mouth position were $1.2{\pm}0.5mm$ (p<0.05). At the TMJ with medially displaced disc, the distances at the closed and open mouth position were $1.3{\pm}0.3\;mm\;and\;0.9{\pm}0.2\;mm$ (p<0.05). Conclusion : The results suggest ultrasonography of TMJ is a reliable imaging technique for assessment of normal disc position.

• Korean Journal of Applied Biomechanics
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• v.29 no.4
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• pp.227-235
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• 2019

Objective: The purpose of this study was to evaluate the effect of passive-acute temperature therapy of the femoral muscle and dynamic warm-up on the countermovement jump performance. Method: Twenty male track and field athletes from national team underwent three treatments applied on the femoral muscles; cold temperature treatment, thermal treatment and dynamic warm-up. The variables extracted at 2 time points (pre-measurement and post measurement) were the temperature of the left and right femoral muscle, displacement & velocity of centre of mass, peak power out, range of motion and moment & power of the knee joint. Results: There was a statistically significant difference in the temperature of the femoral muscle according to measurement time which was high in the order of thermal treatment, dynamic treatment and cold treatment. The jump height was the highest in the dynamic warm-up with no statistically significant difference for the range of motion of the knee joint. The peak power out at dynamic warm-up and the power of the knee joint were statistically significant according to the treatment and measurement time. Conclusion: Local cold and thermal treatment of femoral muscles at ambient temperature did not improve jump performance, while dynamic warm-up was considered to be effective for maintaining the performance of the activities that require strong muscular power.

• International Journal of Automotive Technology
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• v.8 no.6
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• pp.723-730
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• 2007

The typical design of automotive driveshafts generally utilizes Constant Velocity(CV) joints as a solution to NVH. CV joints are an integral part of vehicles and significantly affect steering, suspension, and vehicle vibration comfort levels. Thus, CV joints have been favored over universal joints due to the constant velocity torque transfer and plunging capability. Although CV joints are common in vehicle applications, current research works on modeling CV joint friction and assumes constant empirical friction coefficient values. However, such models are long known to be inaccurate, especially under dynamic conditions, which is the case for CV joints. In this paper, an instrumented advanced CV joint friction apparatus was developed to measure the internal friction behavior of CV joints using actual tripod-type joint assemblies. The setup is capable of measuring key performance of friction under different realistic operating conditions of oscillatory speeds, torque and joint installation angles. The apparatus incorporates a custom-installed triaxial force sensor inside of the joint to measure the internal CV joint forces(including friction). Using the designed test setup, the intrinsic interfacial parameters of CV joints were investigated in order to understand their contact and friction mechanisms. The results provide a better understanding of CV joint friction characteristics in developing improved automotive driveshafts.

• Journal of the Korean Society of Physical Medicine
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• v.9 no.3
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• pp.293-299
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• 2014

PURPOSE: The purpose of this study was to investigate the effect of functional training using a sliding rehabilitation machine (SRM) on the mobility of the ankle joint and balance in children with cerebral palsy (CP). METHODS: The subjects consisted of 11 children who were diagnosed with spastic CP. They carried out the functional training using the SRM for 30 minutes, three times a week, for 8 weeks. Before and after all of the training sessions, the subjects were tested using the Pediatric Balance Scale (PBS) and Gross Motor Function Measurement (GMFM), range of motion (ROM) in the ankle joint, the pennation angle of the gastrocnemius muscle and the fascicle length of gastrocnemius muscle were measured to determine the mobility of the ankle joint and balance ability. RESULTS: There were significant differences between the pre-test and post-test in the PBS and GMFM. The ROM of the ankle joint was significantly increased after the functional training using the SRM. Moreover, the fascicle length was increased and the pennation angle was decreased after the functional training using the SRM, but the difference was not significant. CONCLUSION: These results suggest that functional training using the SRM may have some effect on the mobility of ankle joint and balance in children with CP. According to the results, this study could present an approach to the rehabilitation or treatment of children with CP.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.11
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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.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.11
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• pp.1664-1671
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• 2004

It is necessary to have a model that describes the feature of the knee Joint with a sufficient accuracy. Koreans, however, do not have their own knee joint model to be used in the total knee replacement arthroplasty. They have to use European or American models which do not match Koreans. Three-dimensional visualization techniques are found to be useful in a wide range of medical applications. Three-dimensional imaging studies such as CT(computed tomography) and MRI(magnetic resonance image) provide the primary source of patient-specific data. Three-dimensional knee joint models were constructed by image processing of the CT data of 10 subjects. Using the constructed model, the dimensions of Korean knee joint were measured. And this study proposed a three-dimensional model and data, which can be helpful to develop Korean knee implants and to analyze knee joint movements.

• Nuclear Engineering and Technology
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• v.54 no.10
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• pp.3703-3716
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• 2022

Target alignment technology is one of the most critical technologies in laser fusion experiments and is an important technology related to the success of laser fusion experiments. In this study, by combining the open-loop and closed-loop errors of the target alignment, the Kalman state observer is used to estimate the position of the target, which improves the observation precision of the target alignment. Then the optimized result is used to guide the alignment of the target. This method can greatly optimize the target alignment error and reduce uncertainty. With the improvement of the target alignment precision, it will greatly improve the reliability and repeatability of the experiments' results, thereby improving the success rate of the experiments.