Measuring and compensating for 5-DOF parasitic motion errors in translation stages using Twyman–Green interferometry

A new metrological method is presented that performs simultaneous real-time measurements and compensates for 5-DOF parasitic motion errors in translation stages for precision profiling of optical surfaces. Two plane mirrors are used to obtain motion-dependent interferometric fringes generated by the optical principles of Twyman–Green interferometry. The fringes generated are monitored using high-speed 2D photodiode arrays and analyzed to determine the five separate motion error components in real time. Simultaneously, null control is performed to suppress the measured motion errors independently using piezoelectric actuators through real-time feedback control while the machine axis is moving. The experimental results demonstrate that 5-DOF parasitic motion errors are effectively measured and compensated to within 10 nm for translational motions and 0.15 arcsec for angular motions.     

Synthesis and applications of unsaturated polyester resins based on PET waste

Three types of unsaturated polyester resins were synthesized from the glycolysis of polyethylene terephthalate (PET) plastic waste, considering environment, cost and properties for their applications. These synthesized unsaturated polyester resins could be used for various construction processes and materials such as no dig pipelining (NDR-1), pultrusion (PLR-1) and polymer concrete (PCR-1). PET was taken from common soft-drink bottles, and ethylene glycol (EG), diethylene glycol (DEG) and MPdiol glycol mixtures were used for the depolymerization at molar ratios. The glycolyzed PET 1 ^st products (oligomers) were reacted with maleic anhydride, phthalic anhydride and dicyclopentadiene (DCPD) (especially for polymer concrete) to form unsaturated polyester resins with mixed styrene. The lab scale (1–5 kg) and pilot plant scale-up tests (200 kg) were experimented to evaluate the processing characteristics, viscosity, acid number and curing behaviors. The main properties such as hardness, flexural strength, tensile strength, heat distortion temperature, elongation, and chemical resistance were determined based on the various uses of the three resins. Furthermore, the applicability and the properties of these developed resins were verified through many real application tests.     

Modeling and economic analysis of CO<Subscript>2</Subscript> separation process with hollow fiber membrane modules

The main purpose of the study was to develop a model using ASPEN and Excel simulation method to establish optimum CO₂ separation process utilizing hollow fiber membrane modules to treat exhaust gas from LNG combustion. During the simulation, optimum conditions of each CO₂ separation scenario were determined while operating parameters of CO₂ separation process were varied. The characteristics of hollow fibers membrane were assigned as 60 GPU of permeability and 25 of selectivity for the simulation. The simulation results illustrated that 4 stage connection of membrane module is required in order to achieve over 99% of CO₂ purity and 90% of recovery rate. The resulted optimum design and operation parameters throughout the simulation were also correlated with the experimental data from the actual CO₂ separation facility which has a capacity of 1,000 Nm³/day located in the Korea Research Institute of Chemical Technology. Throughout the simulation, the operating parameters of minimum energy consumption were evaluated. Economic analysis of pilot scale of CO₂ separation plant was done with the comparison of energy cost of CO₂ recovery and equipment cost of the plant based on the simulation model. This work was presented at the 6 ^th Korea-China Workshop on Clean Energy Technology held at Busan, Korea, July 4–7, 2006.     

Highly crosslinked poly(glycidyl methacrylate-co-divinyl benzene) particles by precipitation polymerization

Stable and smooth surface poly(glycidyl metharylate-co-divinylbenzene) (GMA-co-DVB) microspheres composed of various concentrations of DVB from 20 to 90 mol% in acetonitrile medium were prepared without a significant coagulum by precipitation polymerization. The number-average diameter of the microspheres linearly increases from 2.63 to 3.34 μm and the particle size distribution becomes narrower by decreasing the uniformity from 1.10 to 1.02 with the DVB concentration from 20 to 90 mol%. The yield of polymerization increased from 28.9 to 79.7% with the DVB concentration as well. The FT-IR spectrum shows the characteristic peaks at 1725-1650 cm⁻¹ assigned to the confirmation of the polymerization between GMA and DVB. No glass transition temperature and the onset of the thermal degradation temperature at higher temperature indicate that the poly(GMA-co-DVB) is crosslinked; this is evidenced by the swelling ratio measurement relevant to the crosslinking density of the poly(GMA-co-DVB). The swelling test suggested that the poly(GMA-co-DVB) particles would be a core/shell type structure composing of a highly crosslinked DVB rich-phase in the core part and slightly crosslinked GMA rich-phase in the shell part.     

A study on UV-curable coatings for HD-DVD: Primer and top coats

This study relates to the development of coatings for optical discs in high-density digital versatile disc systems (HD-DVD or blue lay disk) that use a high numerical aperture of 0.85 at 405 nm wavelength and have a protective top layer over a primer layer for protection against damage and dust. Ultraviolet-curable raw materials of two acrylic monofunctional monomers ( isobornylacrylate, IBA and tetrahydrofurfurylacrylate, THFA) and two kinds of urethaneacrylate oligomers (OUMD and OUME) have been easily mixed with photoinitiators. Curing rate of these materials was characterized by FT-IR. In case of top coats, VTES (vinyltriethoxysilane) and acrylic acid were added to enhance the abrasion resistance. These two kinds of UV-curable resinous materials having no solvent were synthesized and investigated as means for making a blue ray disk having good optical and mechanical properties. In addition, dynamic characteristics including reflectivity, fluctuation of RF signal and noise level were also investigated.     

Measurements and correlation of effect of cosolvents on the solubilities of complex molecules in supercritical carbon dioxide

A new transparent microscale circulation-type high pressure equilibrium cell with on-line sampling was devised. With this apparatus, experimental solubility of molecularly complex species such as steroids (cholesterol, stigmasterol and ergosterol) and fatty acids (palmitic acid and stearic acid) in supercritical carbon dioxide(sc-C0₂) were measured. Also, to find an appropriate substance for enhancing both the polarity and the solubility power of the SC-CO₂ solvent, we arbitrarily selected three polar substances such as acetone, methanol and water and the effect of these cosolvents on the solubility of solutes in SC-CO₂ are examined. The supercritical phase equilibrium data of solute-cosolvent-sc-CO₂ systems were quantitatively correlated using a new equation of state based on the lattice fluid theory incorporated with the concept of multibody interaction. We found that the addition of tracer amount of acetone or methanol to SC-CO₂ enhances the solubility of all solutes about thirty to sixty times when compared with the case of pure sc-CO₂ However, for the case of cosolvent water, no further enhancement of the solubility of solutes was realized. Also, the versatile fittability of the equation of state proposed in this work was demonstrated with the newly measured ternary supercritical equilibrium data.     

Analysis of the Tubular Single Lap Joint with Nonlinear Adhesive Properties

The majority of the load transfer of an adhesively-bonded joint is accomplished by the nonlinear behavior of the adhesive. In this paper, the torque transmission capability and shear stress distribution of the tubular single lap joint were calculated by incorporating the nonlinear shear properties of the adhesive. The nonlinear shear properties were represented by three different mathematical models such as two-parameter exponential, linear perfectly-plastic and multilinear strain-softening approximations.

From the analyses and experiments, it was found that all the analyses with nonlinear approximations predicted the torque transmission capabilities accurately, but the two-parameter exponential approximation gave the best predictions with the simplest form for use in numerical calculation.     

A porous mixed-valent iron MOF exhibiting the acs net: Synthesis, characterization and sorption behavior of Fe3O(F4BDC)3(H2O)3·(DMF)3.5

A new mixed-valent iron MOF, formulated as Fe₃O(F₄BDC)₃(H₂O)₃·(DMF)_3.5 (1), has been synthesized by using a perfluorinated linear dicarboxylate to link trigonal prismatic Fe₃(μ³-O)(O₂C–)₆ clusters. The structure refinement based on single crystal X-ray diffraction data collected from 1 reveals the material exhibits the acs topology with large channels along the crystallographic c-axis. Due to the presence of fluorine atoms the organic link, 2,3,5,6-tetrafluorobenzene-1,4-dicarboxylate (F₄BDC), has a 63° torsion angle between the carboxylate and aromatic planes, resulting in larger channels compared to those in the isoreticular material MOF-235. While few iron-based MOFs have demonstrated porosity, nitrogen and hydrogen sorption experiments carried out at 77 K proved the porosity of outgassed 1, which has a Langmuir surface are of 635 m²/g and a gravimetric capacity of 0.9 wt% of hydrogen at 1 bar.     

Development and application of VPG simulation technique based on equivalent virtual road profile

A Virtual Proving Ground (VPG) is a vehicle simulation environment used for evaluating durability of the suspension elements. Among the components that comprise the VPG system, the tire model with its complex nonlinear characteristics has most significant impact on the credibility of the estimated durability. This research proposes a method for generating an equivalent road profile as a way to compensate for the limits involved in modeling details of the tire characteristics. The method first identifies the frequency response function from the road heights to the spindle forces, which would contain rich information on the tire’s effect on the vehicle dynamics. Then it back-calculates a road profile using this model and the spindle force measurement. Finally the solution is updated iteratively until it yields the spindle forces close to their measured values. Using the proposed method, an equivalent road profile was successfully generated from a spindle force measurement collected from a physical durability test. In order to investigate validity of the proposed method, durability analysis was performed for a suspension component — a lower control arm. From the preliminary VPG simulation results, it was confirmed that the estimated fatigue life agreed well with the estimation based upon the force measurement.     

Fracture toughness of CFRP laminated plates according to resin content

CFRP(carbon fiber reinforced plastic) has recently found wide use in different industries. The material, however, is very prone to damage from collision with foreign objects. This study aims at finding Ĵ-integral in mode II for CFRP laminated plates based on classical bar theory for dynamic conditions in consideration of inertia forces and eventually to finding dynamic inter-layer fracture toughness. Dynamic inter-layer fracture toughness was observed using an in-house ENF (End Notched Flexure) experimental facility using Split Hopkinson’s Bar (SHPB). Also the variation of the fracture toughness depending on different resin contents and fiber arrangement in the CFRP specimen ([0°3/90°3/0°6/90°3/0°3], [0°20], [0°5/90°10/0°5]) was observed. It was established that under both quasi-static and dynamic load conditions, the critical load and the inter-layer fracture toughness increased sharply following the extension of the resin content. Thus, it may be concluded that the resin content is the major factor determining the inter-layer fracture toughness in the CFRP laminated plate.