• 대한인간공학회:학술대회논문집
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• 대한인간공학회 1995년도 추계학술대회논문집
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• pp.141-155
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• 1995

To understand kinetic characteristics during the process of initation of gait from standing, from the visual cue to toe off of the stance limb, vertical ground reaction forces(GRF) and center of pressure(COP) during gait initation period were evaluate with two force platforms placed side by side in thirty two adults(young 16, elderly 16, each mean age 27.79 and 51.70 years) with no history of 7 neuromusculo-skeletal abnormality. Gaint initation period of swing and stance limbs, percentage of gait initiation period and ratio of the vertical forces to body weight at each peak of the vertical forces of both limbs, and also movement of net COP were measured and described. 2 groups, one of 16 young adults and another of 16 elderly adults, were compared statistically. These data showed the increase of initiation of gait period and the decrease of movement of net COP, nd also can now be used as a part of database when initation of gait in subjects with neuromusculoskeletal abnormalities need to be evaluated.

• 대한기계학회논문집A
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• 제28권9호
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• pp.1262-1269
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• 2004

This study predicts muscle forces acting on the lower extremity when the knee joint is in deep flexion. The whole body was approximated as a link model, and then the moment equilibrium equations at the lower extremity joints were derived far given reaction farces against the ground. Measurement of deep flexion was carried out by placing ten markers on the body. This study calculated the moment acting at each Joint from the equations of force and moment, classified the complicated muscles around the knee joint, and then predicted the muscle forces to balance the joint moment. Two models were proposed in this study: the simpler one that consists of three groups of muscle and the more detailed one of nine groups of muscle.

• 한국운동역학회지
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• 제19권3호
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• pp.519-528
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• 2009

상해 예방을 위해 이용하는 테이핑의 효과는 이미 선행연구들에서 이해할만하게 이야기 되어져 왔지만, 기능적 발목 불안정성을 가진 대상자에게 동적 임무를 가지고 지면반력과 안정성을 분석한 연구는 거의 없다. 본 연구는 발목 불안정성을 가진 선수들을 대상으로 점프 후 착지 시 지면반력 변인과 안정성에 미치는 영향을 알아보는데 있다. 이 실험을 위하여 기능적 발목 불안정성을 가진 14명의 선수가 참가하였고 동작분석과 지면반력 값을 산출하기 위해 적외선 카메라 8대(Vicon MX-F20, Oxford Metric Ltd, Oxford, UK)로 구성된 동작분석시스템(Vicon Motion Systems)과 지면반력기를 사용하였다. 본 연구 결과 발목 불안정성이 있는 선수에게 테이핑의 적용은 착지 시 배측굴곡 각속도, 내번 각속도, 최대 수직지면반력을 감소시켰으며, 안정성과 관련된 변인인 A-P cop, M-L cop에서 안정성을 향상시켰다. 임상에서 발목 불안정성이 있는 선수들에게 상해 예방을 위한 하나의 방법으로 테이핑의 사용을 권장해도 될 것으로 사료된다.

• 한국정밀공학회지
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• 제25권7호
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• pp.79-86
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• 2008

This paper describes the development of wearing intelligent shoe system to measure applied forces and moments (ground reaction forces and moments) on the soles of feet during human walking. In order to walk safely, robot must get the intelligent feet with 6-axis force/moment sensors (Fx sensor (x-direction force sensor), Fy sensor, Fz sensor, Mx sensor (Mx : x-direction moment sensor), My sensor, and Mz sensor) and detect the forces and moments data from the sensors. And the feet must be controlled with the data and controllers. While a human is walking, the forces and moments should be measured and analyzed for robot's intelligent feet. Therefore, the wearing intelligent shoe system should be developed. In this paper, four 6-axis farce/moment sensors and two high speed measuring devices were designed and fabricated, and the wearing intelligent shoe system was made using these. The characteristic tests of the wearing intelligent shoe system were performed, and the forces and moments were detected using it.

• 한국정밀공학회지
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• 제32권4호
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• pp.377-386
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• 2015

Joint force/torque estimation by inverse dynamics is a traditional tool in biomechanical studies. Conventionally for this, kinematic data of human body is obtained by motion capture cameras, of which the bulkiness and occlusion problem make it hard to capture a broad range of movement. As an alternative, inertial motion sensing using cheap and small inertial sensors has been studied recently. In this research, the performance of inertial motion sensing especially to calculate inverse dynamics is studied. Kinematic data from inertial motion sensors is used to calculate ground reaction force (GRF), which is compared to the force plate readings (ground truth) and additionally to the estimation result from optical method. The GRF estimation result showed high correlation and low normalized RMSE(R=0.93, normalized RMSE<0.02 of body weight), which performed even better than conventional optical method. This result guarantees enough accuracy of inertial motion sensing to be used in inverse dynamics analysis.

• 국제초고층학회논문집
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• 제5권3호
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• pp.177-186
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• 2016

Along the subduction-zone of the western Japanese islands, large earthquakes are expected occur around the middle of this century, and long-period ground motions will reach major urban areas, shaking high-rise buildings violently. Since some old high-rise buildings were designed without considering long-period ground motions, reinforcing such buildings is an important issue. An effective method to reinforce existing high-rise buildings is installing additional dampers. However, a problem with ordinary dampers is that they require reinforcement of surrounding columns and girders to support large reaction forces generated during earthquake ground motion. To solve this problem, a deformation-dependent oil damper was developed. The most attractive feature of this damper is to reduce the damping force at the moment when the frame deformation comes close to its maximum value. Due to this feature, the reinforcement of columns, girders, and foundations are no longer required. The authors applied seismic retrofitting with a deformation-dependent oil damper to an existing 54-story office building (Shinjuku Center Building) located in Shinjuku ward, Tokyo, in 2009 to suppress vibration under the long period earthquake ground motions. The seismic responses were observed in the 2011 Tohoku Earthquake, and it is clarified that the damping ratio was higher and the response lower by 20% as compared to the building without dampers.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1996년도 춘계학술대회
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• pp.331-334
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• 1996

The present study was performed to investigate gait characteristics of 30-39 year-old normal adults and 9-10 year-old children. The results focused on joint motions in the sagittal plane and ground reaction forces. The results will play an important role as a valuable data to determine normal and abnormal gait patterns as well as gait characteristics of Korean people.

• International Journal of Precision Engineering and Manufacturing
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• 제9권1호
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• pp.30-33
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• 2008

Understanding the characteristics of amputee gait is key in developing more advanced prostheses. The aim of this study was to quantitatively analyze a stair-climbing task for transfemoral amputees with a prosthesis and to predict the muscle forces and joint moments at musculoskeletal joints using a dynamic analysis. A three-dimensional musculoskeletal model of the lower extremities was constructed from a gait analysis using transformation software for two transfemoral amputees and ten healthy people. The measured ground reaction forces and kinematical data of each joint from the gait analysis were used as input data for an inverse dynamic analysis. Dynamic analyses of an transfemoral amputee climbing stairs were performed using musculoskeletal models. The results showed that the summed muscle forces of the hip extensor of an amputated leg were greater than those of a sound leg. The opposite was true at the hip abductor and knee flexor of an amputated leg. We also found that higher moments at the hip and knee joints of the sound leg were required to overcome the flexion moment caused by the body weight and amputated leg. Dynamic analyses using musculoskeletal models may be a useful means to predict muscle forces and joint moments for specific motion tasks related to rehabilitation therapy.

• Tuberculosis and Respiratory Diseases
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• 제78권3호
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• pp.281-285
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• 2015

Statins lower the hyperlipidemia and reduce the incidence of cardiovascular events and related mortality. A 60-year-old man who was diagnosed with a transient ischemic attack was started on acetyl-L-carnitine, cilostazol, and rosuvastatin. After rosuvastatin treatment for 4 weeks, the patient presented with sudden onset fever, cough, and dyspnea. His symptoms were aggravated despite empirical antibiotic treatment. All infectious pathogens were excluded based on results of culture and polymerase chain reaction of the bronchoscopic wash specimens. Chest radiography showed diffuse ground-glass opacities in both lungs, along with several subpleural ground-glass opacity nodules; and a foamy alveolar macrophage appearance was confirmed on bronchoalveolar lavage. We suspected rosuvastatin-induced lung injury, discontinued rosuvastatin and initiated prednisolone 1 mg/kg tapered over 2weeks. After initiating steroid therapy, his symptoms and radiologic findings significantly improved. We suggest that clinicians should be aware of the potential for rosuvastatin-induced lung injury.

• 한국정밀공학회지
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• 제18권5호
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• pp.137-146
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• 2001

A robust controller with the sliding mode is proposed for stable dynamic walking of the biped robot in this paper. For the robot system to be controlled, which is modeled as 14 DOF rigid bodies by the method of multi-body dynamics, the joint angle trajectories are determined by the velocity transformation matrix. Also Hertz force model and Hysteresis damping element are utilized for the ground reaction and impact forces during the contact with the ground. The biped robot system becomes unstable since those forces contain highly confused noise components and some discontinuity, and modeling uncertainties such as parameter inaccuracies. The sliding mode control is applied to solve above problems. Under the assumption of the bounded estimation errors on the unknown parameters, the proposed controller provides a successful way to achieve the stability and good performance in spite of the presence of modeling imprecisions of uncertainties.