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Backstepping Control and Synchronization for 4-D Lorenz-Stenflo Chaotic System with Single Input
유성훈,현창호,박민용 한국지능시스템학회 2011 INTERNATIONAL JOURNAL of FUZZY LOGIC and INTELLIGE Vol.11 No.3
In this paper, a backstepping design is proposed to achieve stabilization and synchronization for the Lorenz-Stenflo (LS) chaotic system. The proposed method is a recursive Lyapunov-based scheme and provides a systematic procedure to design stabilizing controllers. The proposed controller enables stabilization of the chaotic motion and synchronization of two identical LS chaotic systems using only a single control input. Numerical simulations are presented to validate the proposed method.
Control and Synchronization of New Hyperchaotic System using Active Backstepping Design
유성훈,현창호,박민용 한국지능시스템학회 2011 INTERNATIONAL JOURNAL of FUZZY LOGIC and INTELLIGE Vol.11 No.2
In this paper, an active backstepping design is proposed to achieve control and synchronization of a new hyperchaotic system. The proposed method is a systematic design approach and exists in a recursive procedure that interlaces the choice of a Lyapunov function with the design of the active control. The proposed controller enables stabilization of chaotic motion to the origin as well as synchronization of the two identical new hyperchaotic systems. Numerical simulations illustrate the validity of the proposed control technique
유성훈,조봉준,이예진,김은혜,최성희,임수,이가희,박영주,박경수,장학철 대한당뇨병학회 2011 Diabetes and Metabolism Journal Vol.35 No.1
Background: We examined the change in the levels of incretin hormone and effects of glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide 1 (GLP-1) on insulin secretion in women with previous gestational diabetes (pGDM). Methods: A 75-g oral glucose tolerance test (OGTT) was conducted on 34 women with pGDM. In addition, 11 women with normal glucose tolerance, matched for age, height and weight, were also tested. The insulin, GIP, GLP-1, and glucagon concentrations were measured, and their anthropometric and biochemical markers were also measured. Results: Among 34 women with pGDM, 18 had normal glucose tolerance, 13 had impaired glucose tolerance (IGT) and 1 had diabetes. No significant differences were found in GLP-1 concentration between the pGDM and control group. However, a significantly high level of glucagon was present in the pGDM group at 30 minutes into the OGTT. The GIP concentration was elevated at 30 minutes and 60 minutes in the pGDM group. With the exception of the 30-minute timepoint, women with IGT had significantly high blood glucose from 0 to 120 minutes. However, there was no significant difference in insulin or GLP-1 concentration. The GIP level was significantly high from 0 to 90 minutes in patients diagnosed with IGT. Conclusion: GLP-1 secretion does not differ between pGDM patients and normal women. GIP was elevated, but that does not seem to induce in increase in insulin secretion. Therefore, we conclude that other factors such as heredity and environment play important roles in the development of type 2 diabetes.
Synthesis of ultra‐small gold nanorods: Effect of reducing agent on reaction rate control
유성훈,윤고은,이현승,권재성,이영복,이승현 대한화학회 2023 Bulletin of the Korean Chemical Society Vol.44 No.8
Recently, anisotropic plasmonic nanoparticles with unique optical properties have seen applications in nanomedicine ranging from optical biosensing to bioimaging and drug delivery. For these uses, uniform gold nanoparticles with a very small size and appropriate aspect ratio that maintain optical properties in near‐IR region are desirable. In this study, we synthesized uniform ultra‐small gold nanorods with high yield, using hydroquinone as the reducing agent in the growth solution via the seed‐mediated method. We were able to control the rate of reduction of gold ions by adjusting the volume of hydroquinone, resulting in the controlled growth rate of gold nanorods. Moreover, by adjusting the volume of the gold precursor, we synthesized ultra‐small gold nanorods with dimensions of 16.3 (±2.24) × 5.85 (±0.54) nm (length and diameter). We characterized the ultra‐small gold nanorods by UV–visible‐NIR spectrophotometry, transmission electron microscopy, x‐ray diffraction, and fast Fourier transform techniques.