• International Journal of Precision Engineering and Manufacturing
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• v.7 no.3
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• pp.66-71
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• 2006

Some wheelchair users with neuromuscular disorders experience involuntary extensor thrusts, which may cause injuries via impact with the wheelchair, cause the user to slide out of the wheelchair seat, and damage the wheelchair. Knowledge of the human-generated forces during an extensor thrust is of great importance in devising safer, more comfortable wheelchairs. This paper presents an efficient method for identifying human-generated forces during an extensor thrust. We used an inverse dynamic approach with a three-link human body model and a system for measuring human body motion. We developed an experimental system that determines the angular motion of each human body segment and the force at the footrest, which was used to overcome the mathematical indeterminacy of the problem. The proposed method was validated experimentally, illustrating the force-identification process during an extensor thrust.

• Journal of the Korea Society for Simulation
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• v.20 no.1
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• pp.69-77
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• 2011

Modeling and Simulation(M&S) technology gets an attention from various parts such as industry and military. Especially, military uses the technology to cope with a different situation from the one in the Cold War and maximize the effect of training against the cost in the new environment. In order for the training based on M&S technology to be effective, the situations of a battlefield and a combat must be more realistically simulated. For this, a technique development on Computer-Generated Forces(CGF) which represents a unit's simulation logic and a human's simulated behaviors is focused. The CGF simulating a human's behaviors can be used in representing an enemy force, experimenting behaviors in a future war, and developing a new combat idea. This paper describes a methodology to accomplish Computer-Generated Forces' autonomous intelligence. It explains the process of applying a task behavior list based on the METT+T element onto CGFs. On the other hand, in the domain knowledge of military field manual, fuzzy facts such as "fast" and "sufficient" whose real values should be decided by domain experts can be easily found. In order to efficiently implement military simulation logics involved with such subjectivity, using a fuzzy inference methodology can be effective. In this study, a fuzzy inference methodology is also applied.

• Transactions of the Korean Society of Automotive Engineers
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• v.13 no.1
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• pp.132-139
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• 2005

The driving position of head restraints and the relative risk of neck injury were studied in the computer simulation. MADYMO human model with the detail neck model was used to define the magnitude and direction of internal forces acting on the cervical spine during rear-end impact and to determine the effect of the initial position of the occupant's head with respect to the head restraints. Maximum reaction forces were generated during the head contact to the restraint and relatively large forces were generated at each spinal components in lower cervical spine in proportion to backset and height distance increasement.

• Korean Journal of Computational Design and Engineering
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• v.17 no.1
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• pp.62-70
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• 2012

This paper proposes a novel discomfort assessment method for truck ingress and egress motions based on the maximum-voluntary-contraction (MVC) ratios of muscles obtained by biomechanical analysis of human musculoskeletal models. In this study, a human motion to enter and exit a truck cabin with different types and heights of footsteps is first measured using an optical motion capture system and load sensors. Next, in a biomechanical analysis system, a human musculoskeletal model with contacting conditions on footsteps and handles is modeled, and then joint torques and muscles forces are calculated by inverse dynamics of the musculoskeletal model with the motion data. Finally, the MVC ratios for the muscles are calculated and their statistical values are used as the measure of discomfort. To ensure the feasibility of our method, subjective discomfort levels have been investigated through the participants' experiments and questionnaires and compared to the results of our method. Comparing to the existing methods based on joint angles or torques, our approach provide a more essential criterion for discomfort because it is based on the muscle contraction by which an active human motion is basically generated.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.1593-1597
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• 2003

The home service robot supports human beings by performing various kinds of works at home. This paper presents a simple control method for opening a door from the viewpoint of the mobile manipulation. The simulation shows various results of path planning and motion planning for opening a door. The joint trajectories were generated by the simulation system. In general, a six-axis force/torque sensor at an end-effector is needed in order to maintain the static equilibrium of the manipulator. But we show another method. From three components of applied forces which was directly obtained by the three-axis force sensor and three components of applied forces which was indirectly estimated by the joint-torque sensors, all of joint torques that will exactly balance forces at the end-effector in the static situation can be found. It is more practical method than using a six-axis force sensor in a wrist. Experimental results have shown that the opening a door can be realized more effectively from the suggested control method of mobile manipulation.

• Proceedings of the KSME Conference
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• 2000.04a
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• pp.261-267
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• 2000

A mathematical model was developed to calculate the muscle force of lower extremity during the gait. We constructed a model of human locomotion, which includes a muscle-skeletal system with 7 segments and 16 lower limb muscles. Using a optimization technique, muscle forces variation of the lower extremity during the gait were generated and its result was verified by comparing a experimental results of EMG analysis. Moreover. the walking movement of the model could be compared quantitatively with those of experimental studies in human by inverse dynamics.

• Microbiology and Biotechnology Letters
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• v.48 no.4
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• pp.423-428
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• 2020

In vitro evolution is a powerful technique for the engineering of yeast strains to study cellular mechanisms associated with evolutionary adaptation; strains with desirable traits for industrial processes can also be generated. There are two distinct approaches to generate evolved strains in vitro: the sequential transfer of cells in the stationary phase into fresh medium or the continuous growth of cells in a chemostat bioreactor via the constant supply of fresh medium. In culture, evolutionary forces drive diverse adaptive mechanisms within the cell to overcome environmental or intracellular stressors. Especially, this engineering strategy has expanded to the field of human cell lines; the understanding of such adaptive mechanisms provides promising targets for the treatment of human genetic diseases and cancer. Therefore, this technology has the potential to generate numerous industrial, medical, and academic applications.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.8
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• pp.37-44
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• 2008

Nowadays, the increasing global competition forces manufacturer to reduce the cost and time for implementation of manufacturing system. The AR(augmented reality) technology as a new human-machine interface introduces a noteworthy perspective for a new manufacturing system design. Using AR technology, a physically existing production environment can be superimposed with virtual planning objects. Therefore, the planning tasks can be validated without modeling the surrounding environment of the production domain during short process planning time. In this paper, we introduce the construction of AR browser and determine the optimal environment parameters for field application of AR system through lots of tests. And, many methods such as multi-marker coordinate system, division of virtual objects and so on, are proposed in order to solve the problems suggested from initial field test. Based on these tests and results, the test-bed of C/Pad assembly system is configured and robot program for C/Pad assembly is generated based on AR system.

• Korean Journal of Applied Biomechanics
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• v.12 no.2
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• pp.393-405
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• 2002

When our body is immersed in water, we experience weightlessness. The degree of weightlessness that we experience varies depending on the proportion of the body immersed in water, being governed by the relationship between the weight of body and the buoyant force acting on the body. Human body during the performance of swimming in no exception to these influences. Swimmers body is subject to a time and position dependent force system. Even the magnitude of the buoyant force acting on the swimmers body at every given instant and the corresponding position of the CB change continuously. The findings of this study support the following conclusions. The buoyancy torque was the primary source of bodyroll exhibited by front crawl swimmers performing at distance pace, accounting for 88 % of the bodyroll. Faster swimmers used buoyancy more effectively to generate bodyroll, partially supporting the postulation that an effective use of buoyancy for bodyroll may reduce the generated hydrodynamic forces to be wasted in non-propulsive directions and maximize forward propulsion.

• The Journal of Korea Robotics Society
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• v.18 no.4
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• pp.481-486
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• 2023

The purpose of this study is to optimize parameters of a contact model to obtain similar ground contact force of human walking. Dynamic walking simulation considering ground contact is performed to determine load specifications when developing walking assist robots. Large contact forces that are not observed in actual experimental data occur during the simulation at the initial contact (e.g., heel contact). The large contact force generates unrealistic large joint torques. A lower exoskeleton robot with no ankles is developed with the Matlab simscape and the nonlinear hyper volumetric contact model is applied. Parameters of the nonlinear hyper volumetric model were optimized using actual walking contact force data. As a result of optimization, it was possible to obtain a contact force pattern similar to actual walking by removing the large contact force generated during initial contact.