• Journal of the Korea Convergence Society
• /
• v.13 no.5
• /
• pp.307-312
• /
• 2022

The purpose of this study was to investigate the effects of wearing functional clothing over calf muscles on the muscle function of the calf and to verify whether functional clothing can increase calf muscle function. The participants of the study were 21 male students from University B who had no lower extremity abnormality. The measurement method was measured at 30°/sec and 120°/sec angle speed before and after wearing functional clothing on the right and left calves using Humac Norm of CSMI, a constant speed muscle function measuring instrument. No significant difference was observed during dorsiflexion when wearing functional clothing, but in plantar flexion, muscle strength and muscle endurance were significantly increased. Therefore, wearing functional clothing over the calves showed a positive effect on improving exercise function, and future research suggests a study comparing the degree of muscle function improvement between those wearing functional clothing and those not wearing it for athletes training ahead of the competition.

• Structural Engineering and Mechanics
• /
• v.75 no.4
• /
• pp.477-485
• /
• 2020

Finite element (FE) model based structural damage detection (SDD) methods play vital roles in effectively locating and quantifying structural damages. Among these methods, structural model updating should be conducted before SDD to obtain benchmark models of real structures. However, the characteristics of updating parameters are not reasonably considered in existing studies. Inspired by the l_∞ norm regularization, a novel anti-sparse representation method is proposed for structural model updating in this study. Based on sensitivity analysis, both frequencies and mode shapes are used to define an objective function at first. Then, by adding l_∞ norm penalty, an optimization problem is established for structural model updating. As a result, the optimization problem can be solved by the fast iterative shrinkage thresholding algorithm (FISTA). Moreover, comparative studies with classical regularization strategy, i.e. the l₂ norm regularization method, are conducted as well. To intuitively illustrate the effectiveness of the proposed method, a 2-DOF spring-mass model is taken as an example in numerical simulations. The updating results show that the proposed method has a good robustness to measurement noises. Finally, to further verify the applicability of the proposed method, a six-storey aluminum alloy frame is designed and fabricated in laboratory. The added mass on each storey is taken as updating parameter. The updating results provide a good agreement with the true values, which indicates that the proposed method can effectively update the model parameters with a high accuracy.

• Journal of Institute of Control, Robotics and Systems
• /
• v.14 no.7
• /
• pp.615-623
• /
• 2008

This paper proposes an $H_{\infty}$ controller design method for Takagi-Sugeno (T-S) fuzzy systems using a fuzzy basis-function-dependent Lyapunov function. Sufficient conditions for the guaranteed $H_{\infty}$ performance of the T-S fuzzy control system are given in terms of linear matrix inequalities (LMIs). These LMI conditions are further used for a convex optimization problem in which the $H_{\infty}-norm$ of the closed-loop system is to be minimized. To facilitate the basis-function-dependent Lyapunov function approach and thus improve the closed-loop system performance, additional decision variables are introduced in the optimization problem, which provide an additional degree-of-freedom and thus can enlarge the solution space of the problem. Numerical examples show the effectiveness of the proposed method.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2006.05a
• /
• pp.167-170
• /
• 2006

This study proposes a new wavelet watermark technique based on the Linear Bit Expansion. To ensure the security of the watermark, it is Amold Transformed before embedding. Then the wavelet transformation of watermark and original images is processed. Since the size of the watermark image is a quarter of the original site, it uses linear bit-expansion to enlarge the watermark image. Lastly, watermark is inserted in a given intensity to the corresponding low frequency subbands of the wavelet-transformed images proposed in this paper. When detecting the presence of watermark, the similarity between extracted watermark and the original watermark is compared applying the F norm function.

• International Journal of Fuzzy Logic and Intelligent Systems
• /
• v.8 no.3
• /
• pp.170-174
• /
• 2008

The measurement of performance of a process considering both the location and the dispersion of information about the process is referred to as the process capacity indices (PCIs) of interest, $C_{pk}$. This information is presented by the mean and standard deviation of the producing process. Linguistic variables are used to express the evaluation of the quality of a product. Consequently, $C_{pk}$ is defined with fuzzy numbers. Lee [Eur. J. Oper. Res. 129(2001) 683-688] constructed the definition of the $C_{pk}$ index estimation presented by fuzzy numbers and approximated its membership function using the "min" - norm based Zadeh's extension principle of fuzzy sets. However, Lee's result was shown to be invalid by Hong [Eur. J. Oper. Res. 158(2004) 529-532]. It is well known that $T_w$ (the weakest t-norm)-based addition and multiplication preserve the shape of L-R fuzzy numbers. In this paper, we allow that the fuzzy numbers are of L-R type. The object of the present study is to propose a new method to calculate the $C_{pk}$ index under $T_w-based$ fuzzy arithmetic operations.

• Communications of the Korean Mathematical Society
• /
• v.21 no.4
• /
• pp.719-727
• /
• 2006

In this paper, we study the boundedness and the com-pactness of weighted composition operator between $H^{\infty}$ and Bergman type space on the unit ball of $\mathbb{C}^n$. Also, the norm of corresponding weighted composition operator is computed.

• Journal of the Korean Mathematical Society
• /
• v.49 no.5
• /
• pp.927-945
• /
• 2012

An approximation of singular source terms in elliptic problems is developed and analyzed. Under certain assumptions on the curve where the singular source is defined, the second order convergence in the maximum norm can be proved. Numerical results present its better performance compared to previously developed regularization techniques.

• 제어로봇시스템학회:학술대회논문집
• /
• 1991.10a
• /
• pp.40-45
• /
• 1991

This paper deals with the design of feedback controllers which minimize the $H^{\infty}$-norm of the weighted sensitivity function. Using the Lagrange multiplier method and the Nevanlinna-Pick interpolation theory, an algorithm which stabilizes a plant and makes the output to track the reference signal is proposed..

• 제어로봇시스템학회:학술대회논문집
• /
• 1991.10a
• /
• pp.46-51
• /
• 1991

An algorithm of finding a solution to an $H^{\infty}$-minimization problem is proposed, and the solution is obtained explicity in terms of closed-form. We construct an optimal controller subject to the interpolation constraints such that $H^{\infty}$-norm and the minimized value of transfer function matrix are equal.l.

• Korean Journal of Mathematics
• /
• v.5 no.2
• /
• pp.127-134
• /
• 1997

On the setting of the upper half-space of the euclidean n-space, we study some properties of harmonic little Bloch functions and we show that for a given harmonic little Bloch function $u$, there exists unique harmonic conjugates of $u$, which are also little Bloch functions with appropriate norm bounds.