• Journal of the Korean Society for Precision Engineering
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• v.33 no.3
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• pp.173-181
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• 2016

This paper reports on the development of a roller-cam clutch mechanism. This mechanism can transfer bidirectional torque with high backdrivability, as well as increase actuation energy efficiency, in electrical exoskeleton robots. The developed mechanism was installed at the robot knee joint and unclutched during the swing phase which uses less metabolic energy, thereby functioning as a passive joint. The roller-cam clutch aimed to increase actuation energy efficiency while also producing high backdrivability by generating zero impedance for users during the swing phase. To develop the mechanism, mathematical modeling of the roller-cam clutch was conducted, with the design having more than three safety factors following optimization. Titanium (Ti-6AL-4V) material was used. Finally, modeling verification was done using ANSYS software.

• Journal of muscle and joint health
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• v.7 no.1
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• pp.40-52
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• 2000

Recently with the development in computer technology and its communication system, many changes in medical informatics enable us to use various medical information regardless of time or place. There are many home pages on the web, which provide medical counseling and hospital information. On May 11th 1999, Korean Rheumatology Health Professions Society began its new service as a home page on the web with various rheumatologic health information, questioning/ answering, and so on. This study was undertaken to examine the content and the purpose of health counseling on the web. The data was collected from 173 questioners who visited questioning/ answering site in the KRHPS home page for May 11th, 1999 through November 10th, 1999. Most of the questioners consulted the health problems of their or their families. Over two thirds of them were already diagnosed medically. Rheumatoid arthritis was the most frequent one. Other diseases, such as, osteoarthritis, ankylosing spondylitis, Still's disease were also on the list. Most of the questioners wanted to know treatment strategies, to consult about their symptoms, and to make diagnosis. And many questioners wanted detailed explanations about their diseases or the informations regarding the hospital. These findings suggest that the health counseling on the web may be used to supplement the lack of direct medical interviews with doctors. It also is expected to guide the patients to the right direction.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.643-644
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• 2006

The purpose of this study is to experimentally analyze swing motion with soft golf clubs and compare with that with normal golf clubs. Soft golf is newly devised recreational sport based on golf but focus on the playability for the elderly. The subject fur the experiment performed swing motion using a normal golf club and a soft golf club in turn. The swing motion of the subjects was tracked using an opto-electric three-dimensional motion analysis system. The results were compared against those obtained with a normal golf club. The range of motion was analyzed along with top head speed for two cases. It was found that higher club head speed could be achieved with reduced range of motion at lumbar joint using soft golf club when compared against the swing using regular club. The lower range of motion fur lumbar bending means reduced risk of injury at the joint. So, it is projected that we can reduce the risk of injury with soft golf while maintaining the club head speed.

• Korean Journal of Materials Research
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• v.26 no.7
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• pp.376-381
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• 2016

For the development of a low-melting point filler metal for brazing aluminum alloy, we analyzed change of melting point and wettability with addition of Sn into Al-20Cu-10Si filler metal. DSC results showed that the addition of 5 wt% Sn into the Al-20Cu-10Si filler metal caused its liquidus temperature to decrease by about 30 oC. In the wettability test, spread area of melted Al-Cu-Si-Sn alloy is increased through the addition of Sn from 1 to 5 wt%. For the measuring of the mechanical properties of the joint region, Al 3003 plate is brazed by Al-20Cu-10Si-5Sn filler metal and the mechanical property is measured by tensile test. The results showed that the tensile strength of the joint region is higher than the tensile strength of Al 3003. Thus, failure occurred in the Al 3003 plate.

• Transactions of the Korean Society of Automotive Engineers
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• v.15 no.1
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• pp.56-63
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• 2007

In case of bus rollover, the body structure of the bus should be designed to ensure the survival space for passengers. So, this study focuses on evaluating rollover strength through a computer simulation using the commercial code, LS-DYNA3D at the initial stage of vehicle development. For this study, section structure was modeled using a simple beam element, and impact boundary conditions required by ECE(Economic Commission for Europe) regulation No.66 were applied. In order to confirm the validity of the beam element bus model, the results compared with the test results and shell element bus model. The analysis errors from beam element bus model are due to the difference in strain energy of joint area between beam and shell model. In this study, a method for the joint modeling was suggested by using nonlinear springs to which the collapse mechanisms were applied.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.26 no.1
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• pp.89-99
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• 2017

This paper describes the development of a thigh wearable robot for power assistance during stair climbing. In the wearable robot developed in this study, high-power BLDC motors and high-capacity harmonic reduction gears are used to effectively assist the thigh muscle during stair climbing. In particular, normal ground and stair are distinguished accurately by using wireless smart shoes, and the stair climbing assistance is performed by activating the actuators at an appropriate time. Impedance of the hip joint was effectively reduced by performing friction compensation of the gears, and a wearing adjustment mechanism was designed to fit the robot to the thigh by conveniently modifying the width and tilting angle of the robot using set collars. Consequently, the performance of the developed thigh wearable robot was verified through stair climbing experiments with EMG measurement.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.8
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• pp.771-782
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• 2017

This paper describes the development of a wearable robot to assist ankle power for the elderly. Previously developed wearable robots have generally used motors and gears to assist muscle power during walking. However, the combination of motor and reduction gear is heavy and has limitations on the simultaneous control of stiffness and torque due to the friction of the gear reducer unlike human muscles. Therefore, in this study, Mckibben pneumatic muscle, which is lighter, safer, and more powerful than an electric motor with gear, was used to assist ankle joint. Antagonistic actuation using a pair of pneumatic muscles assisted the power of the soleus muscles and tibialis anterior muscles used for the pitching motion of the ankle joint, and the model parameters of the antagonistic actuator were experimentally derived using a muscle test platform. To recognize the wearer's walking intention, foot load and ankle torque were calculated by measuring the pressure and the center of pressure of the foot using force and linear displacement sensors, and the stiffness and the torque of the pneumatic muscle joint were then controlled by the calculated ankle torque and foot load. Finally, the performance of the developed ankle power assistive robot was experimentally verified by measuring EMG signals during walking experiments on a treadmill.

• The Journal of the Korea Contents Association
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• v.21 no.4
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• pp.137-152
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• 2021

In North Korea, where there was little external activity, the number of overseas academic paper publications has recently increased. This study aims to quantitatively analyze North Korean papers published abroad to identify changes in North Korea's research and development trends, and to explore the possibility of developing them through joint research with domestic researchers in the future. To this end, since 1986, frequency analysis and network analysis have been conducted on papers published overseas including North Korean researchers. The analysis was conducted on authors, research institutes, countries, and research fields, and changes were analyzed before and after Kim Jong-un took office. According to the results of the analysis, as the number of foreign papers published rapidly increased during the eight years after Kim Jong-un took office, the composition of the top researchers, research institutes, and researchers with high influence in joint research also changed a lot. After Kim Jong-un came to power, the proportion of North Korean researchers and research institutes increased relatively, and a network component was formed between researchers with high influence on joint research, so it was observed that they focused on specific research topics. It was found that the major foreign collaborators or research institutes of North Korean researchers were from China.

• International Journal of Concrete Structures and Materials
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• v.10 no.4
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• pp.479-497
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• 2016

Many experimental studies have evaluated the in-plane behavior of reinforced concrete frames in order to understand mechanisms that resist progressive collapse. The effects of transverse beams, frames and slabs often are neglected due to their probable complexities. In the present study, an experimental and numerical assessment is performed to investigate the effects of transverse beams on the collapse behavior of reinforced concrete frames. Tests were undertaken on a 3/10-scale reinforced concrete sub-assemblage, consisting of a double-span beam and two end columns within the frame plane connected to a transverse frame at the middle joint. The specimen was placed under a monotonic vertical load to simulate the progressive collapse of the frame. Alternative load paths, mechanism of formation and development of cracks and major resistance mechanisms were compared with a two-dimensional scaled specimen without a transverse beam. The results demonstrate a general enhancement in resistance mechanisms with a considerable emphasis on the flexural capacity of the transverse beam. Additionally, the role of the transverse beam in restraining the rotation of the middle joint was evident, which in turn leads to more ductile behavior. A macro-model was also developed to further investigate progressive collapse in three dimensions. Along with the validated numerical model, a parametric study was undertaken to investigate the effects of the removed column location and beam section details on the progressive collapse behavior.

• Journal of Korea Technology Innovation Society
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• v.11 no.4
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• pp.532-562
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• 2008

Recently, one of the issues to be discussed from the viewpoint of product management in National R&D Programs is about the management of intellectual property produced by joint research and development. According to existing legislative system, the main R&D institute and collaborative enterprise own the patent produced by joint R&D activities together at the rate of investment. But, there are many discussions if that is right in legal principles and in substance. Patents by Cooperative National R&D Programs are very different from common patents because of its characteristics and have scheme controlled complexly by related laws and ordinances. This paper aims to review the legal theory on the possession and utilization of patents produced by Cooperative National R&D Programs, and to try to find out the improvement of existing legislative system. For this purpose, after looking into the meaning and the legal system of Cooperative National R&D Programs, and examining the ruling theory on the possession and utilization of co-invented patent, finally research the problems and improvement of existing related legislative system.