• Journal of Biomedical Engineering Research
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• v.22 no.3
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• pp.293-301
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• 2001

A patient-specific musculoskeletal model, whose parameters can be identified noninvasively, was developed for the automatic generation of patient-specific stimulation pattern in FES. The musculotendon system was modeled as a torque-generator and all the passive systems of the musculotendon working at the same joint were included in the skeletal model. Through this, it became possible that the whole model to be identified by using the experimental joint torque or the joint angle trajectories. The model parameters were grouped as recruitment of muscle fibers, passive skeletal system, static and dynamic musculotendon systems, which were identified later in sequence. The parameters in each group were successfully estimated and the maximum normalized RMS errors in all the estimation process was 8%. The model predictions with estimated parameter values were in a good agreement with the experimental results for the sinusoidal, triangular and sawlike stimulation, where the normalized RMS error was less than 17%, Above results show that the suggested musculoskeletal model and its parameter estimation method is reliable.

• Structural Engineering and Mechanics
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• v.52 no.4
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• pp.663-686
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• 2014

This paper deals with free vibration analysis of bidirectional functionally graded annular plates resting on a two-parameter elastic foundation. The formulations are based on the three-dimensional elasticity theory. This study presents a novel 2-D six-parameter power-law distribution for ceramic volume fraction of 2-D functionally graded materials that gives designers a powerful tool for flexible designing of structures under multi-functional requirements. Various material profiles along the thickness and in the in-plane directions are illustrated by using the 2-D power-law distribution. The effective material properties at a point are determined in terms of the local volume fractions and the material properties by the Mori-Tanaka scheme. The 2-D differential quadrature method as an efficient and accurate numerical tool is used to discretize the governing equations and to implement the boundary conditions. The fast rate of convergence of the method is shown and the results are compared against existing results in literature. Some new results for natural frequencies of the plates are prepared, which include the effects of elastic coefficients of foundation, boundary conditions, material and geometrical parameters. The interesting results indicate that a graded ceramic volume fraction in two directions has a higher capability to reduce the natural frequency than conventional 1-D functionally graded materials.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.1
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• pp.79-86
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• 2007

The Magnus effect measurement apparatus was designed and built for spinning wind tunnel model which would simulate the rotation of projectiles. Prior to the high speed test, the ground functional test and the low speed test were carried out in the Agency for Defense Development's Low Speed Wind Tunnel(ADD-LSWT) at spin rates from about 6,000 to 10,000 rpm. Magnus force and moment were measured on the spinning projectile model at velocity of 100 m/s. It was shown that the Magnus force and moment were linear function of spin parameter. The test results were compared with Magnus test run on the same configuration in the Arnold Engineering Development Center's Propulsion Tunnel 4T(AEDC-4T).

• Journal of the Microelectronics and Packaging Society
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• v.23 no.4
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• pp.107-112
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• 2016

In this paper, the hydrophobic rough surfaces were prepared by employing a conventional nano-imprint lithography technique, and the effects of surface parameter, ratio of the top surface to the flat unit cell, on the impingement behaviors of liquid droplet were investigated to improve robustness of hydrophobic functionality. The critical height defined for the transition from rebound to fragmentation is measured by droplet impingement test in order to study dynamic behavior of an impinged droplet. It showed the critical height decreased with high surface parameter while it increased with low surface parameter. However, the critical height decreased again as surface parameter decreased further. Observed results suggest that the optimized surface pattern should be designed for the increased critical height.

• International Journal of Precision Engineering and Manufacturing
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• v.3 no.2
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• pp.52-60
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• 2002

Axiomatic Design is the one of many useful methods for making a good design. In this method, the independency of Functional Requirements (FRs) is an important property to determine whether the design is good or not. Until now so many designers have decided the independency between FRs by their own decisions. The way depending on inspiration is simple and fast, but it can not be considered as a precise conclusion. Also there are not exact rule that evaluate the quantitative independence between FRs. This paper will show the way to evaluate the quantitative independence of FRs from the comparison between FRs of lower levels, and develop more efficient and objective tool in Axiomatic Design.

• Proceedings of the KSME Conference
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• 2001.06c
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• pp.445-450
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• 2001

DVD(Digital Versatile Disk) is the data storage media devised to make high storage density and high data input/output possible. Therefore higher rotational speed and better accuracy in optical pick-up are required compared with the existing optical storage device. These operational functional requirements are concerned with abilities of optical storage device. Especially, High rotational speed is deeply concerned with the noise and vibration of optical storage device, is important problem in development of optical storage device so much. This paper propose a new concept ROM media of optical storage device named as Cylindrical ROM media, and evaluate this by means of Axiomatic approach and empirical data.

• Proceedings of the KSME Conference
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• 2001.06c
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• pp.426-431
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• 2001

When we use various multimedia programs such as 3D-game, visual conference, dial-pad phone by internet service, we make use of headset generally. As internet system is magnified more and more, a demand of headset will be increasing continuously. Because microphone was fixed by headset, it has many inconveniences for using headset. For these reasons, new concept headset is needed nowadays. Main idea of development of headset is very the automatic operation system of microphone. There are many process variables in appling new technology to the conventional headset. They can be solved by using axiomatic approach method which is very useful design method for designing new products. Its main character is scientific and analytical. The goal of this research is to design and manufacture a new headset model with axiomatic design method. In this paper, a new concept headset was presented by mapping the relation between functional requirements and design parameters.

• Korean Journal of Mathematics
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• v.6 no.1
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• pp.27-46
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• 1998

We are concerned with an optimal control problem governed by a Poisson equation in which body force acts like a control parameter. The cost functional to be optimized is taken to represent the error from the desired observation and the cost due to the control. We recast the problem into the mixed formulation to take advantage of the minimax principle for the duality method. The existence of a saddle point for the Lagrangian shall be shown and the optimality system will be derived therein. Finally, to attain an optimal control, we combine the optimality system with an operational technique. By achieving the gradient of the cost functional, a convergent algorithm based on the projected gradient method is established.

• Journal of Institute of Control, Robotics and Systems
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• v.11 no.1
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• pp.13-18
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• 2005

This paper considers a design problem of the repetitive control system for linear systems with time-varying norm bounded uncertainties. Using the Lyapunov functional for time-delay systems, a sufficient condition ensuring robust stability of the repetitive control system is derived in terms of an algebraic Riccati inequality (ARI) or a linear matrix inequality (LMI). Based on the derived condition, we show that the repetitive controller design problem can be reformulated as an optimization problem with an LMI constraint on the free parameter.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.10 no.4
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• pp.155-158
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• 1985

A simple active-R filter is proposed by utilizing only four resistors and two operational amplifiers. This filter has multi-functional characteristics and decreases the ratio of resistors. The sensitivity of $W_r$ and $Q_r$ as the parameter of filter is very low and the operating frequency of this active-R filter is possible in the high frequency. The integration of this active-R filter is easy due to the decrease in the number of resistors and the lowering of the ration of resistors. The experiment shows that all the characteristics of this active-R filter are in accordance with thory.