• Journal of Applied Biological Chemistry
• /
• v.62 no.4
• /
• pp.367-374
• /
• 2019

Euphorbia humifusa Willd (EuH), called Ttang-Bin-Dae in Korea, is a traditional medicinal plant widely used for its anti-inflammatory and antiviral activity. Ethyl acetate (EA) extracts of EuH (EA/EuH) inhibit invasion and metastasis by inhibiting tumor necrosis factor TNFá-induced matrix metalloproteinases (MMP)-9 expression in human breast cancer cells. However, the bioactive components of EA/EuH mediating the inhibition of MMP-9 expression have not been identified. In the present study, three bioactive constituents of EA/EuH were isolated using high-performance liquid chromatography. Nuclear magnetic resonance spectroscopy revealed isoquercetin, avicularin, and astragalin as the bioactive compounds responsible for preventing TNFα-induced MMP-9 mRNA expression in breast cancer cells. These findings suggest that isoquercetin, avicularin, and astragalin could be used as valuable anti-metastatic agents against metastatic cancers.

• International Journal of Precision Engineering and Manufacturing
• /
• v.3 no.4
• /
• pp.78-86
• /
• 2002

In this paper, LMI (Linear Matrix Inequality) based on H$\_$$\infty$/ controller for a lire of sight (LOS) stabilization system. It shows that the proposed controller has more excellent stabilization performance than that of the conventional PI-Lead controller. An H$\_$$\infty$/ control has been also applied to the system for reducing modeling errors and the settling time of the system. The LMI-based H$\_$$\infty$/ controller design is more practical in view of reducing a run-time than Riccati-based H$\_$$\infty$/ controller. This H$\_$$\infty$/ controller is available not only to decrease the gain in PI-Lead control, but also to compensate the identifications for the various uncertain parameters. Therefore, this paper, shows that the proposed LMI-based H$\_$$\infty$/ controller had good disturbance attenuation and reference input tracking performance compared with the control performance of the conventional controller under any real disturbances.

• Transactions on Control, Automation and Systems Engineering
• /
• v.1 no.2
• /
• pp.106-112
• /
• 1999

This paper presents an H$\infty$ controller design method for linear systems with time-varying delayed states, inputs, and measurement outputs. Using a Lyapounov unctional , the stability for delay systems is discussed independently of time delays . And a sufficient condition for the existence of H$\infty$ controllers of n-th order is given in terms of three matrix inequalities. Based on the positive-definite solutions of their matrix inequalities, we briefly explain how to construct H$\infty$ construct H$\infty$ controller, which stabilizes time-delay systems independently of delays and guarantees an H$\infty$ norm bound.

• Journal of the Korean Institute of Intelligent Systems
• /
• v.20 no.2
• /
• pp.214-219
• /
• 2010

This paper deals with a nonlinear fuzzy $H_{\infty}$ filter design for SOC(state of charge) estimation in Lithium polymer battery. The dynamic equation of the battery cell is modeled as a T-S fuzzy system and the filter is designed via solutions of linear matrix inequalities. In order to illustrate the performance of the designed filter, a computer simulation is performed using the experimental data with the UDDS(urban dynamometer driving schedule) current profile.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.13 no.3
• /
• pp.172-179
• /
• 2003

Linear matrix Inequality based $H_\infty$ robust controller is designed to control the motion of a 4-axis unbalanced rigid asymmetric rotor supported and controlled by two active magnetic bearings in this paper. To this end, the equations of motion of the system are derived via Hamilton's variational principle and transformed to a state-space form for the standard $H_\infty$ control problem. LMI-based controller, which does not require additional assumptions beyond the usual stabilizability and detectability assumptions, is designed based upon the pole place weighting function and loopshaping technique. The obtained results are compared with those reported in the available literature and the efficiency of the proposed LMI-based $H_\infty$ control is revealed.

• International Journal of Automotive Technology
• /
• v.8 no.4
• /
• pp.483-491
• /
• 2007

A closed form solution of a composite mechanics system is performed for the investigation of elastic-plastic behavior in order to predict fiber stresses, fiber/matrix interfacial shear stresses, and matrix yielding behavior in short fiber reinforced metal matrix composites. The model is based on a theoretical development that considers the stress concentration between fiber ends and the propagation of matrix plasticity and is compared with the results of a conventional shear lag model as well as a modified shear lag model. For the region of matrix plasticity, slip mechanisms between the fiber and matrix which normally occur at the interface are taken into account for the derivation. Results of predicted stresses for the small-scale yielding as well as the large-scale yielding in the matrix are compared with other theories. The effects of fiber aspect ratio are also evaluated for the internal elastic-plastic stress field. It is found that the incorporation of strong fibers results in substantial improvements in composite strength relative to the fiber/matrix interfacial shear stresses, but can produce earlier matrix yielding because of intensified stress concentration effects. It is also found that the present model can be applied to investigate the stress transfer mechanism between the elastic fiber and the elastic-plastic matrix, such as in short fiber reinforced metal matrix composites.

• KSBB Journal
• /
• v.11 no.6
• /
• pp.676-680
• /
• 1996

The characteristics of controlled drug release were studied for a biodegradable drug delivery system. A biodegradable chitosan matrix was prepared after swelling chitosan with 10%-acetic acid and adding sulfadiazine. The release behavior of sulfadiazine from the chitosan matrix was studied using the Higuchi's diffusion controlled model in phosphate buffer solutions of pH 7.4 and pH 1.2. The drug release time was delayed by increasing the content of sulfadiazine. The drug release at pH 7.4 was more delayed than that at pH 1.2. The reason is that chitosan has greater swelling abilities at low pH than at high pH. The apparent release rate constant(K) increased as the concentration of drug increased. In shoat, the formulation the biodegradable chitosan matrix to suppress the burst effect of drug release mechanism, which led to a sustained release pattern.

• Reproductive and Developmental Biology
• /
• v.39 no.3
• /
• pp.49-57
• /
• 2015

In order to achieve successful in vitro production of embryo, it is necessary to establish intrauterine environment during in vitro culture. Thus, this study was investigated to establish embryo culture system using co-incubated collagen matrix gel (CM) with endometrial epithelial cells (EC). Endometrial epithelial cells were isolated from porcine endometrium at follicular phase, the cells seeded in insert dish for co-incubation with CM-coated culture dish. Then, culture media treated with/without 2.0 IU/ml hCG or 10 ng/ml $IL-1{\beta}$. After incubation for 24 h, the co-incubated insert dishes were removed from CM-coated culture dish before embryo culture. Embryos at 48 h after in vitro fertilization (IVF) were cultured on the dish for 120 h with porcine zygote medium. We determined PTGS-2 expression in the ECs, VEGF protein in co-incubated CM with EC and observed cleavage rate and blastocyst development of embryos at 168 h after IVF. In result, expression of PTGS-2 was higher at co-incubated EC with hCG and $IL-1{\beta}$ groups than EC without hCG and $IL-1{\beta}$. The VEGF protein was detected at co-incubated CM with EC, EC treated with hCG and $IL-1{\beta}$ groups higher than CM group. Also, cleavage rate was no significantly difference among all group, however, blastocyst development was significantly higher in co-incubated CM with EC treated with hCG group than un-treated groups (p<0.05). Therefore, we suggest that novel embryo culture system using co-incubated collagen matrix gel with endometrial epithelial cells treated with $IL-1{\beta}$ is beneficial and useful for enhancing the production of porcine blastocysts in vitro.

• Journal of the Institute of Electronics Engineers of Korea SC
• /
• v.41 no.5
• /
• pp.19-27
• /
• 2004

A delay dependent fuzzy $H_2/H_{\infty}$ controller design method for delayed fuzzy dynamic systems is considered. Using delay-dependent Lyapunov function, the asymptotical stability and $H_2/H_{\infty}$ performance problem are discussed. A sufficient condition for the existence of fuzzy controller is presented in terms of linear matrix inequalities(LMIs). A simulation example is given to illustrate the design procedures and performances of the proposed methods.

• International Journal of Automotive Technology
• /
• v.2 no.3
• /
• pp.117-122
• /
• 2001

For a dynamic analysis of a constrained multibody system, it is necessary to have a routine for satisfying kinematic constraints. LU decomposition scheme, which is used to divide coordinates into dependent and independent coordinates, is efficient but has great difficulty near the singular configuration. Other method such as the projection matrix, which is more stable near a singular configuration, takes longer simulation time due to the large amount of calculation for decomposition. In this paper, the row space and the null space of the Jacobian matrix are proposed by using the pseudo-inverse method and the projection matrix. The equations of the motion of a system are replaced with independent acceleration components using the null space of the Jacobian matrix. Also a new hybrid method is proposed, combining the LU decomposition and the projection matrix. The proposed hybrid method has following advantages. (1) The simulation efficiency is preserved by the LU method during the simulation. (2) The accuracy of the solution is also achieved by the projection method near the singular configuration.