The present investigation studies the effects of heat treatment temperature on the corrosion behavior of cold worked 6111 aluminum alloy. The specimens were cold worked at different cold working ratios, namely, 10, 20, and 40%. They were then heat treated at 100, 200, and 400°C. Corrosion tests were performed using tap water with 0.01 M sodium hydroxide, as a corrosive medium, and the weight loss of the corroded specimens plus the corrosion rates were then calculated. Experimental results showed that corrosion rates depended on the amount of cold working percentage and the heat treatment temperature. Corroded surfaces were also photographed and analyzed. The graphs revealed large numbers of corrosion pits, in addition to crevice corrosion and fine grains of rust, and these rusts were cultivated to scales that were detached from the surfaces and were subjected to corrosive medium.

In this investigation, we propose a flexible structured illumination microscope (FSIM) to eliminate mechanical moving parts for the phase shifts in the spatial pattern and longitudinal scanning of the specimen. In order to prevent these mechanical motions, we adopt a focus-tunable lens and digital micromirror device (DMD) to replace the lateral motion of the pattern and the scanning of the specimen, respectively, which leads to the enhancement of rapid and precise measurement results for measuring the 3D surface profile of specimens. To realize the proposed system, two types of flexible structured illumination microscopes, Macro and micro types, were constructed and their performances were verified with a plane mirror and step height specimens.

Equipment used in the semiconductor manufacturing process generally have a flow rate control system for each nozzle to regulate the flow rate of chemical solution fed to the wafer. In existing flow rate control systems, flow rate overshoots occur because of excess pressure and the control rates of the overshoots are less because additional operation time is required for the electric valves. In this study, to address the shortcomings of existing flow rate control systems, we proposed a method to improve the speed of flow rate control by introducing a constant pressure valve. The constant pressure valve controls the flow path via gas pressure, thereby facilitating prompt control and efficiently improving the flow rate overshoot caused by the pressure overshoot. To improve the control speed and control stability of the constant pressure valve, a three-step automatic control speed application function was developed, and the measured valve, control amount mapping function, and pre-open function were defined to reduce the initial control speed. The experimental results showed a measurement precision within 1% of the target flow rate and stable control performance as well as control speed reduction from 3 seconds in existing systems to 2 seconds or less for the proposed system.

This research investigated the cooling performance of the motor in electric vehicle depending on the shape of the cooling channel. The research, conducted numerically by FLUENT V20.1, focused on the numerical study of heat transfer coefficients to find an optimum design shape with high cooling performance. To compare the cooling performance, the temperatures in the coil and cooling channel were analyzed. As a result of forced convection, the average cooling channel velocity of Case 2 was 38% faster than Model N and 34% faster than Case 1. The maximum temperature of the cooling channel of Case 2 was 8.7% lower than Model N and 5.6% lower than Case 1. The minimum temperature of the coil of Case 2 was 2.7% lower than Model N and 4.3% lower than Case 1. The maximum temperature of the coil of Case 2 was 4.6% lower than Model N and 2.9% lower than Case 1. Ultimately, cooling channel of Case 2 showed the best cooling performance and improved driving performance for motor durability.

This research is to investigate the cooling performance of the motor in the electric vehicle depending on the cooling channel fin. The research focused on numerical study of the temperature of coil and cooling channel and the heat transfer coefficients to find a optimum design shape with high cooling performance at three different cases. To compare the convective cooling performance of the three cooling channels, local position (R) are displayed on the surface of the coils with a large temperature deviation. This research was performed on forced convection and was numerically analyzed by FLUENT V20.2. Owing to forced convection by the same mass flow, the average cooling channel velocity in Case 3 was 17.4% faster than Case 1 and 8.6% faster than Case 2. Out of the three cases, the highest heat transfer coefficient was found in the cooling channel and coil of Case 3, which had two cooling fins. The coil maximum temperature of Case 3 with 2 cooling fins was 4.7% lower than Case 1 without cooling fins and 1.7% lower than Case 2 with 1 cooling fin. Ultimately, Case 3 with two cooling fins provided the best cooling performance and improved driving motor performance for motor durability.

In this study, the deformation of a large industrial door subjected to wind load was investigated through computational fluid dynamic and structural analyses. The model for the structural analysis was simplified by considering the PVC curtain and wind bar in the shape of the actual door. The pressure distribution acting on the front of the door was obtained from computational fluid dynamic analysis and the deformation of the door was obtained from structural analysis. According to the results, the pressure distribution was not uniform on the front of the door and varied depending on the location. The distribution of the deflection in the wind bar was obtained and it was found that the position of the maximum deformation occurred slightly above the center of the door. Finally, the deformation of the door could be predicted by analyzing the deflections of the wind bar subjected to different wind speeds through regression analysis.

Ultrasonic cutting is used not only for cutting various materials such as metals and non-metals, but also for bone cutting of the human body or for various surgical operations. In recent, ultrasonic cutting technology is being applied for cutting various food products such as cakes, pizza, and cheese. It is shown that ultrasonic vibrations for cutting food products enables high-precision and high-quality cutting, and the quality of the cutting surface is affected by the shape of food products and cutting conditions. However, most of the studies have been on industrial cutting horns that can be used in large-scale grocery factories, but these cutting horns are very different from the shape of knives used in the households. Accordingly, research or technology development for ultrasonic cutting knives that can be used in household has not been studied. Therefore, this study developed a knife that can cut or process food by applying ultrasonic vibration while having a shape similar to the existing knife as possible so that it can be used in general. To develop such a knife, a modal analysis was performed using the finite element method for knife models of various shapes, and a suitable model for a kitchen knife was proposed.

In this study, the design of an axial steam turbine that is installed for a using waste pressure. Airfoils and flow fields are designed based on 1D and 2D meridional plane design techniques. The 3D geometry of the steam turbine is designed considering the 1D and 2D design parameters. The turbine is designed with an average radius of 287 mm and rotates at 8,300 re v/min. The inlet boundary condition of the steam turbine was applied in consideration of the installation condition of the waste pressure turbine. When analyzing the results of the numerical simulation, the performance of the steam turbine is predicted with an output of 3.5 MW and isentropic efficiency of 88.4%. The choked flow in the nozzle throat and the flow separation in the suction side on the blades are predicted numerically, and it is expected to be a study to determine the cause of the reduction in efficiency of the steam turbine.

Low back injury (LBI) often occurs during manual materials handling (MMH). Intradiscal pressure (IDP) is used to assess the risk of the LBI and is measured in vivo or by computer simulation. As for computer simulation, motion analysis and finite element (FE) analysis are usually employed. In this study, a FE model has been developed for L4-L5 segment with high risk of injury to predict LBI during manual lifting tasks. The FE model was composed of lumbar vertebrae, discs, and ligaments and a calibration process was performed to set the nonlinear material properties of the intervertebral disc. To validate the developed FE model, IDP and range of motion (ROM) under in vitro loading conditions were compared to the experiments and other FE studies in literature. Within in vitro range, IDP and ROM from the FE model were in agreement with results from previous studies. The FE model developed in this study can be scaled according to the subject used in the analysis integrating FE analysis to motion analysis, and is expected to be used in future work to estimate IDP and stress/strain in joint structures during occupational activities.