Poly (3-hexylthiophene)/polymethylmethacrylate [P3HT/PMMA] composite thin film was prepared by the spin-coating method by composing a prism-coupled waveguide. The UV-visible spectrum was recorded in the range of 300-900nm to determine its optical absorption property. An Nd:YAG laser with a wavelength of 1064nm, a pulse width of 5ns, and a repetition frequency of 10Hz was used for optical bistability measurements. The optical bistable characteristics of the prism-coupled waveguide comprised of P3HT/PMMA composite thin film was measured for different input laser power intensity using optical bistable measuring equipment. The effect of organic gas treatment on the optical bistable behavior of the P3HT/PMMA quasi-waveguide was observed. The effect of PMMA molecular weight on the optical bistability of the P3HT/PMMA waveguide was also investigated.

This paper presents an unsteady flow modeling of an electrorheological (ER) valve system and verifies its effectiveness through experimental investigation. After designing a cylindrical ER valve, a dynamic model for unsteady flow of ER fluid is derived by considering the fluid inertia. The field-dependent pressure drop of the unsteady flow is then calculated and validated with the experimental result. In order to clearly observe the difference between the unsteady flow model and the steady model, the flow rate of the ER valve is analyzed under low frequency and high frequency sinusoidal inputs. In addition, in order to demonstrate the effectiveness of the proposed unsteady flow model, a position control system activated by ER valves is constructed. The dynamic model of the control system is formulated on the basis of the unsteady flow analysis, and control responses such as flow rate, pressure drop and displacement are compared between the unsteady flow and the steady flow models.