In this study, the effect of flow rate ratio (R) and total flow rate (Q) on the surface temperature of thermal barrier coatings (TBC) was investigated using a newly developed small-scale methane-oxygen burner rig. Subsequently, the failure mode of electron beam physical vapor deposition (EB-PVD) TBC was examined, and the relationship between surface temperature and coating life was established. The surface temperature of the TBC was found to be strongly dependent on both the flow rate ratio and the total flow rate. Specifically, surface temperature exhibited a proportional relationship with total flow rate, while it showed an inverse relationship with flow rate ratio. The failure mode of the EB-PVD TBC involved a gradual increase in delamination from the rim to the center of the coin-shaped specimen, and this failure mode was found to be independent of surface temperature. Additionally, it was determined that the surface temperature of EB-PVD TBC has a perfectly inverse linear relationship with coating life. This finding implies that the derived linear regression line from the burner rig test can be directly used to predict coating life for any untested surface .temperature.

In this study, we developed a new vertical thermal gradient rig that uses methane-oxygen fuel. We conducted thermal gradient testing on a thermal barrier coating system, with a flame temperature of 1,900℃. Our results showed that the maximum surface temperature reached 1,065℃, while the temperature difference between the surface temperature and the temperature of the middle substrate (ΔT) was 70oC. Using the same torch as in this study, our finding suggest that the total flow rate of the flame should be above 12.4 LPM, and the gun distance should be less than 8 cm, to simulate a surface temperature of 1,300℃, while keeping the substrate temperature below 1,000℃. This will ensure that the flame is wide enough to cover the entire surface area of the thermal barrier coating.

Slot-die coating is a method of coating a wide layer of thin film on a substrate. It has the advantages of large-area coating with high reproducibility and uniform thickness. For this reason, it has been widely applied in various industrial manufacturing fields. To secure higher coating uniformity under various coating conditions, estimating and controlling the flow rate of the coating solution discharged to the substrate is crucial. In this study, a practical gravimetric flow rate measurement method for slot-die coating uniformity evaluation has been introduced. The gravimetric method is a technique for accurately and quickly estimating the flow rate through the mass change over time using a precision weighing balance. We analyzed the measurement principle and errors caused by fluid mechanics such as hydrodynamic force or capillary force. The dynamic properties based on fluid viscosity were also evaluated for flow rates from 5 to 50 μL/s. The repeatability of the fabricated measurement system was ~1.5 μL/s. Finally, it was confirmed that the settling time for high-viscosity fluid could be advanced by 56.4% through multi-step feedforward control.

A theoretical and numerical FSI approach is used to predict the mass flow in a Coriolis flow meter. By comparing with the experimental results according to the relationship between mass flow and the time phase difference at the inlet and outlet of the tubes, the authors could determine the reliability of the present results from a theoretical and numerical approach in this paper. The mass flow has a linear relationship with the time phase difference, which is a unique parameter to measure true mass flow; therefore, for more precise measurement, it should be long enough to detect the signal within the given time resolution afforded by the detecting system and control system. Compact size and manufacturability, which are the important factors that decide the product competitiveness, should also be considered. In this paper, inversed triangle shaped and conventional U shaped Coriolis flow meters are designed, their time phase difference performances are predicted, and the results from experiments are well matched with the predicted results from the above-mentioned analysis.

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.

The high voltage direct current (HVDC) device has been used to transmit electrical power with an advanced technology of semiconductors. The sustainable energy generation technologies of solar power and windmills are demanding that the HVDCs have high performance and reliability. In this regard, the cooling performance of the HVDC becomes a significant research topic because the temperature increase affects the operation of the device. The evaluation system to assess the cooling performance has been developed and is proposed in this paper. The experimental apparatus is presented in detail. Our experiments have shown the accuracy of flow rates, pressure drops, and the temperatures in the desired measurement points. We have successfully developed an evaluation system of the cooling performance of the HVDC device which has 2.48 kW of heat dissipation.

Various chemicals are used for semiconductor process. In particular, the most important element in the etching and cleaning process is chemical liquid. An ultrasonic flow meter is used to monitor the supplying amount of chemical solution. If the ultrasonic flow meter contains bubble inside the liquid, measurement cannot be performed or measurement error will be occurred. In this research, the waveform was improved by zero-crossing processing so that the influence on measurement performance is negligible even if the bubble in the chemical solution is included. Consequently, the amplitude of the sound wave is attenuated. Existing flow meters monitor the amplitude value to determine the authenticity of the signal and to filter the noise. The improved method in this study distinguishes noise waves and monitors signal frequency. Flow measurement was carrying out even when the amplitude was resulting only less than 3% of input level volt. The system developed of this study has shown an exact measuring performance compared with the other make’s flow meters.

Reactors are needed to produce polymeric polymers as materials for OLED (Organic Light Emitting Diode). There are many types of reactors that assist in producing chemical reactions. One type, called a coil type, is a continuous reactor that has many advantages compared to other reactors. It can not only manufacture products continuously, but is cheaper and therefore cost efficient. A continuous coil type reactor was designed and manufactured for this study. A precise flow rate cannot be determined because of the numerous variables. An experimental flow rate is obtained when combining the following information: the valve opening angle, the revolution velocity of the screw and the temperature of the reaction. As a result, the study is considered that people who use this device will refer to this to control flow rate and time for reaction.

Recently, demands for difficult-to-cut materials with high mechanical properties have been increased in various industrial fields, such as the aerospace and automobile industries. Because difficult-to-cut materials have high mechanical properties, it is difficult to achieve conventional machining. Therefore, many researchers have been studying the machining methods for difficult-to-cut materials. One of the many studies of how to cut difficult-to-cut materials involves plasma-assisted machining (PAM) is a machining method that softens difficult-to-cut materials by a plasma heat source to remove by the cutting tool. PAM has various machining conditions, and it is very important to determine the optimal conditions to improve machining accuracy and efficiency. In this study, the cutting force was analyzed by using a gas flow rate and power which are the easiest to control in the PAM system. The results of this study can be applied to PAM data under optimum conditions.