Key Engineering Materials Vols. 297-300

Abstract: The main purpose of this investigation was to evaluate the performance of the solar hot water heater for dwellings in a long period of time. In order to evaluate the performance, there were 11 solar hot water heaters located in Gwangju Chosun University examined for their performance in 30 month period as a long term. The specific monitoring systems of each heater were constructed for the demonstrational research and the data base associated to each monitoring systems were assembled for an extensive analysis for variety of data obtained. The demonstrational experiments were conducted through following the routine procedures of 4 specific tests (the replicated drainage test, the daily drain test, the daily agitation test, the short-term test). The performance evaluation was based on the performances in insulating and solar collecting and the experimental routines and the performance experiments had incorporated the consumers’ use and need of the product. The ultimate goals of this investigation were to achieve consumers’ trust on the products and to promote the extensive distributions of the solar hot water heaters. The demonstrational research of this investigation was to evaluate the performance of the solar hot water heater for the residents for a long period of time. This research will be continued extensively.

Abstract: Ceramic ferrule that is a major part of the optic connectors requires a high level of precision in a grinding chamfer. After the grinding chamfer, there is a problem in that the subsurface damages cannot be removed. The objective of this study was to analyze the grinding force and the associated stress generated in a ceramic ferrule during cylindrically grinding chamfer using Finite Element Analysis (FEA). A two-dimensional finite element model was constructed with the grinding parameters and the mechanical properties of the ferrule as input variables. The size of the geometric model was the same with the ceramic ferrule. The experimental results achieved by the SEM photograph were compared with those from the FEM. The FEM results were in correlation with those of the experiments.

Abstract: By imitating the vibration isolation mechanism and special organic texture of woodpecker’s brain, a bionics mechanics-based structure model is constructed for the vibration isolation system of ultra-precision device. In consideration of compound vibration environment and non-linearity of the ultra-precision device, a fuzzy-PID (PID stands for Proportional, Integral and Derivative.) active vibration control system is developed, its operation is that fuzzy control is adopted while the error is big and PID control is adopted while the error is small. The performance of the vibration control system is validated by numerical simulation. The simulation results show that the bionic vibration control system has good performance against floor disturbances and direct disturbing force. It can be applied to the vibration isolation system of the ultra-precision measuring and manufacturing device.

Abstract: Recently, the demand for Ultra-precision products is rapidly increasing, especially in such industries as semi-conductors, computers, aerospace, and precision machinary. Ultra-precision processing is also extremely needed for NT in the field of mechanical engineering. Lately, together with drastic advancement of electronic and photonics industry, the need of Ultra-precision processing is increased in the manufacturing of various kernel parts, which are connected with these industrial fields. Especially, motion accuracy to nanometers is required in order in stroke of hundreds millimeters according as the diameter of the processed object great and the processing accuracy rises. In this case, the response speed absolute delay due to inertial mass of the moving parts is very large. Therefore, real-time motion error compensation becomes the barest necessity. In this paper, we used ultra-precision cutting unit (UPCU) to cope with the problem. A special UPCU was designed and tested to obtain sub-micrometer from accuracy in diamond turning of flat surfaces. The thermal growth spindle error was compensated in real time using the UPCU driven by piezoelectric actuator along with a laser encoder displacement sensor.

Abstract: The characteristic of flow fields in elbow has been numerically studied to develop anti-abrasive elbows, which is typically equipped in coal-burning power plants, for conveying highvelocity particle-laden fluids. Specially, a vortex flow field in the pipe experiencing particle abrasion was formed and particle flow simulation was conducted. The governing equations for threedimensional, turbulent flow fields were discretized by FVM and solved by the SIMPLE algorithm.

Abstract: We report on a novel method for the surface modification of indium tin oxide (ITO) in LCD glass by direct exposure to a dielectric barrier discharge (DBD) at atmospheric pressure and room temperature. To remove the organic contaminants from the surfaces of ITO film in LCD glass, the atmospheric pressure RF glow discharge plasma was used. Argon (Ar) and oxygen (O2) were used as the carrier gas and reactive gas, respectively. The addition of O2 gas to Ar decreased the contact angle of water and increased the surface cleaning rate due to the increase of oxygen radicals in the plasma. The chemical characteristics of ITO surface after the plama treatment were investigated using X-ray photoelectron spectroscopy (XPS), and new carboxyl group bond was produced. The contact angle of 64° before the plasma treatment was decreased to 7° in the processing condition with oxygen flow rate of 50 sccm, treatment speed of 100mm/sec, and input power of 300W. These hydrophilic effect will be very useful in the manufacturing processes of LCD glass.

Abstract: In this paper the effects of an enhanced solution and aging on the strengthening behavior of commercially available 2024Al alloy were investigated using tension testing and scanning electron microscopy. A differential scanning calorimeter (DSC) was used to measure the incipient melting behavior and then determine the technological parameter of an enhanced solution heat treatment for strengthening the 2024Al alloy. The results show that the incipient melting behavior of the commercially available 2024Al alloy was characterized by a small amount of liquid phase between the temperatures 773K to 788K. A solution treatment, appropriately enhanced by slowly increasing the solution temperature from 773K to 783K at a heating rate of 5K/h, can make the final solution temperature of the alloy higher than the conventional solution temperature of 773K. This improves the constituent phase solution without the formation of overheated microstructures. The results are the strength, especially the yield strength, and the resistance to over-aging can both be considerably improved without a large deterioration to tensile ductility.

Abstract: A method of systematic modeling was presented to analyze dynamic characteristics of an assembled thin plates structure. Based on dynamic fundamental solutions of a thin plate, governing boundary equations in the lateral and internal vibration of the thin plate are established by using a boundary element method (BEM). According to assembled conditions on the boundary, dynamic characteristics equations of the assembled thin plates structure are deduced. In order to raise calculating efficiency and avoid complicated programming operation, an approach of frequency scanning is introduced to analyze dynamic characteristics of the assembled thin plates structure. The natural frequencies and modal shapes are obtained fast and effectively. By numerical calculation and experiments given, the established method has not only good precision but also high efficiency.

Abstract: The effective breadth of a stiffened plate under bending was investigated. The design parameter of an effective breadth was used when a stiffened plate subjected to a lateral loading was considered. Due to the lateral loads there was shear transmission through the plate from the stiffener, which leads to a non-uniform longitudinal stress distribution across the plate width the effective breadth that takes into account a shear lag can be calculated by the simple beam theory. For a tanker, the existing effective breadth concept has been used when longitudinal stiffeners are fixed at adjacent web frames. However, the effective breadth of each classification’s formula can’t be applied to flexible support condition such as the one prevailing in Ro-Ro vessel. The effective breadth according to the rules of several classification societies was compared and a way to get an accurate analysis as suggested.