• The Journal of Korean Physical Therapy
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• v.20 no.1
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• pp.49-56
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• 2008

Purpose: Lack of a valid prognosis of gross motor development in children with cerebral palsy (CP) and the absence of longitudinal data on which to base an opinion in Korea have made it difficult to plan treatment and counsel prognosis issues accurately. The purposes of this study were to examine whether the Gross Motor Function Classification System (GMFCS) is valuable to prognostication about gross motor progress in children with CP in Korea. Methods: Medical records of 61 patients were retrospectively reviewed that visited outpatient department and were diagnosed as CP. Various information was surveyed including CP type, visual acuity, cognitive function, motor acquisition age, ambulatory status, development curves of Gross Motor Function Measure (GMFM) according to each of the 5 level of GMFCS. All of them were compared with other studies. Also the gross motor development curves and the maximum GMFM score derived from this study were compared with the Palisano's report and the Rosenbaum's report. Results: Based on a total of 494 GMFM assessments provided by this study, the 5 distinct motor development curves and the maximum GMFM score were created. These observations is corresponding with the Palisano's and the Rosenbaum`s Development curves. Conclusion: The 5 distinct motor development curves (GMFCS) that were created by Palisano's and Rosenbaum's study is useful in Korea, providing parents and clinicians with a means to plan interventions and to judge progress over time.

• 제어로봇시스템학회:학술대회논문집
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• 1991.10a
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• pp.928-933
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• 1991

In this study, the authors developed a hydraulic motor performance test system which automatically accomplishes the procedure of basic performance test and represents the data obtained in the test as performance curves. The software is made as conversation style between a computer and a user, so even to novices it is very easy to use. The most important point of this study is to get desirable isoefficiency curves. As some defined number of data are obtained at actual test, additional data necessary for desirable isoefficiency curves are generated numerically by interpolation. Basis spline function is used to get more smooth representative performance curves.

• 유체기계공업학회:학술대회논문집
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• 2004.12a
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• pp.189-192
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• 2004

Utilizing pump selection softwares is becoming a new general trend in pump industries, substituting the old fashioned pump catalogs. One of the most powerful pump selection softwares is developed, which features pump performance viscosity correction function as well as pump selection based on the exact pump performance curves, NPSH warning, automatic determination of impeller diameter cutting to meet the customer's performance specification, performance simulation for the rpm and diameter variation, standard motor recommendation according to the motor standards and enclosure types and automatic pump datasheet generation for sales submission, automatic pump drawings and dimension generation for installation check and part preparation. This software provides pump distributors and customers with a quick, easy and exact pump selection, various performance curves review (system curves, performance curve of series or parallel operation) of the selected pumps.

• The Journal of the Acoustical Society of Korea
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• v.15 no.1
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• pp.10-16
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• 1996

Ultrasonic motor is a motor driven by the stator via frictional contact forces generated from ultrasonic vibration of piezoelectric elements. In order to control the ultrasonic motor, it is essential to measure accurately the motor characteristics with respect to driving parameters such as frequency, voltage, phase difference and duty ratio of the driving signals. In this paper, a PC-interfaced evaluation device is developed, and the characteristic curves of the fabricated ultrasonic motor are measured with those parameters. All driving parameters are processed digitally. The developed evaluation device can facilitate charateristics measurements effectively, and provide a base for digital control of the ultrasonic motor.

• Transactions of Materials Processing
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• v.32 no.3
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• pp.122-128
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• 2023

As electric vehicles (EV) have increasingly replaced the conventional vehicles with internal combustion engines (ICE), most of automotive makers are actively devoting to the technology development of EV parts. Accordingly, the manufacturing process for power source has been also shifting from engine/transmission to EV motor/reducer system. However, lack of experience in developing the EV motor still remains as a technical challenge. In this paper, we employed the forming simulation based on finite element modeling to solve this problem. In particular, in order to increase the accuracy of the forming simulation, we introduced the elastic-plastic constitutive model parameters for polymer-copper hybrid wire by investigating the individual strain-stress curves, and elastic modulus of polymer and copper. Then, the reliability of modeling procedure was confirmed by comparing the simulated results with experiments. Finally, the identified mechanical properties and finite element modeling were applied to a hairpin forming process, which involves multiple deformation paths such as bending, pressing, widening, and twisting. The proposed numerical approach can replace common experience or experiment based trials by reducing production time and cost in the future.

• Tribology and Lubricants
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• v.12 no.3
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• pp.100-106
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• 1996

Gerotor pumps and motors are widely used in lubrication and hydraulic actuator systems. Compared with internal gear pumps and motors, they have many advantages. However, the gerotor profiles have not been suff'lciently analyzed theoretically. Therefore, it is very difficult for designer to decide the specifications of the gemtor profiles, and calculation of flow rate and minimum distance of clearance in the contact point of inner and outer rotor is not yet confirmed. In this paper, when we design inner and outer rotor concurently, we have analyzed the gerotor profiles and displayed the calculated results such as flow rate, minimum distance between inner and outer rotor and gerotor profiles.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.3
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• pp.319-325
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• 2015

High-strength steel has replaced mild steel as the material of choice for truck decks or frames, owing to the growing demand for lightweight vehicles. Although studies on the weld fatigue characteristics of mild steel are available, studies on high-strength steels have been seldom conducted. In this study, firstly, we surveyed a chosen number of approaches and selected the Radaj method, which uses the notch factor approach, as the one suitable for evaluating the fatigue life of commercial vehicles. Secondly, we obtained the S-N curves of HARDOX and ATOS60 steel welds, and the F-N curves of the T-weld and overlapped-weld structures. Thirdly, we acquired a general S-N curve of welded structures made of high-strength steel from the F-N curve, using the notch factor approach. Fourthly, we extracted the weld fatigue characteristics of high-strength steel and incorporated the results in the database of a commercial fatigue program. Finally, we compared the results of the fatigue test and the CAE prediction of the example case, which demonstrated sufficiently good agreement.

• 한국신재생에너지학회:학술대회논문집
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• 2006.11a
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• pp.290-296
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• 2006

Control algorithms and implementation issues for a wind turbine simulator are presented for realistic emulation of variable wind characteristics using a lab-scale motor and generator set. When the average wind speed nd turbulence level is given, the torque reference of prime mover is decided through various blocks, such as random wind speed generator, blade characteristic curves, and tower effect compensation. The variable nature of wind can be implemented and tested by not only the computer simulation but also the hardware-in-loop-simulator (HILS). Some application examples of HILS include the development and test of turbine control software for more efficient and stable operation. Feasibility of the proposed simulator has verified by computer simulations and experiment.

• Journal of the Korean Society for Precision Engineering
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• v.29 no.8
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• pp.896-905
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• 2012

Recently, the application of the plastic material to automotive components and structures has steadily increased to satisfy demands on the saving of overall weight and the improvement of energy efficiency. The objective of this paper is to investigate the development of a bumper back-beam using a thermoplastic olefin (TPO). The bumper back-beam was designed to be manufactured from the injection molding process. In order to obtain a proper design of the bumper back-beam, three-dimensional finite element analyses were performed for various design alternatives. Stress-strain curves for different strain rates were measured by high speed tensile tests of the TPO to consider strain rate effects in the FEA. The influence of the sectional shape and the rib formation on the contact force-intrusion curves, the deflection and the energy absorption rate of the bumper back-beam was examined. From the results of the examination, a proper design of the bumper back-beam was acquired. The bumper back-beam consisting of TPO was fabricated from the injection moulding process and the vibration welding. Pendulum crash tests were carried out using the fabricated bumper back-beam. The results of the tests showed that the designed bumper back-beam can satisfy requirements of the federal motor vehicle safety standard (FMVSS). Through the comparison of the previously designed bumper back-beam with the newly designed bumper back beam, it was noted that the weight of the designed bumper back-beam is lighter than that of the previously designed bumper back beam by nearly 16 %. In addition, it was considered that the newly designed bumper back beam can improve recycling of the bumper back-beam.

• Transactions of the Korean Society of Automotive Engineers
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• v.13 no.2
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• pp.37-43
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• 2005

A haptic steering system which reflects steering reaction torque has been developed for a fixed base vehicle simulator. The haptic steering system consists of a steering effort sensor, MR-clutch, AC servo motor and controller. In order to generate realistic steering torque feel to driver and at the same time to meet real-time simulation requirement, 3D torque map is constructed by experimental data and torque generation algorithm using the torque map has been also developed. 3D torque map is constructed using curve fitting and interpolation of the measured values of the steering angle, velocity and steering torque from actual slalom test on the proving ground. In order to carry out performance test of the developed haptic steering system, a fixed based vehicle simulator is constructed by integrating real time vehicle dynamics module, VR-video/audio module, and the haptic steering system. Steering torque and steering angle curves have been obtained from virtual testing in the vehicle simulator and performance of the haptic steering system has been evaluated.