• Journal of Korea Foundry Society
• /
• v.35 no.5
• /
• pp.109-113
• /
• 2015

In this study, the measurement of FN (ferrite volume fraction) and the solution annealing ratio at a temperature of $1130^{\circ}C$ were determined with 15A elbow fittings of shell cast SSC13, and the corrosion resistance with and without austenitizing solution annealing were investigated in comparison with AISI304. The delta ferrite phase was observed in the material due to the slow cooling effect of the shell mold casting. However, the delta ferrite phase decreased gradually with the solution annealing at a temperature of $1130^{\circ}C$. The hardness generally decreased with a heat treatment; however, its corrosion resistance was improved with the heat treatment. In addition, when a passivation treatment was applied, its corrosion ratio showed the lowest value. The pattern of general corrosion decreased due to the decrease in the delta ferrite phase with the solution annealing treatment. Consequently, it is suggested that the corrosion resistance of SSC13 elbow fittings can be improved by increasing the ratio of any solution annealing treatment used and by decreasing the ferrite phase. The relationship between the ratio of solution annealing and delta ferrite is expressed as follows: SA (solution annealing ratio,%) = 98 - FN (ferrite volume fraction, %).

• JSTS:Journal of Semiconductor Technology and Science
• /
• v.14 no.2
• /
• pp.163-168
• /
• 2014

Bottom gate thin-film transistors were fabricated using solution processed IGZO channel layers with various gallium composition ratios that were annealed on a hot plate. Increasing the gallium ratio from 0.1 to 0.6 induced a threshold voltage shift in the electrical characteristics, whereas the molar ratio of In:Zn was fixed to 1:1. Among the devices, the IGZO-TFTs with gallium ratios of 0.4 and 0.5 exhibited suitable switching characteristics with low off-current and low SS values. The IGZO-TFTs prepared from IGZO films with a gallium ratio of 0.4 showed a mobility, on/off current ratio, threshold voltage, and subthreshold swing value of $0.1135cm^2/V{\cdot}s$, ${\sim}10^6$, 0.8 V, and 0.69 V/dec, respectively. IGZO-TFTs annealed at $300^{\circ}C$, $350^{\circ}C$, and $400^{\circ}C$ were also fabricated. Annealing at lower temperatures induced a positive shift in the threshold voltage and produced inferior electrical properties.

• JSTS:Journal of Semiconductor Technology and Science
• /
• v.15 no.2
• /
• pp.249-254
• /
• 2015

Solution-derived amorphous indium-gallium-zinc oxide (a-IGZO) thin-film-transistor (TFTs) were developed using a microwave irradiation treatment at low process temperature below $300^{\circ}C$. Compared to conventional furnace-annealing, the a-IGZO TFTs annealed by microwave irradiation exhibited better electrical characteristics in terms of field effect mobility, SS, and on/off current ratio, although the annealing temperature of microwave irradiation is much lower than that of furnace annealing. The microwave irradiated TFTs showed a smaller $V_{th}$ shift under the positive gate bias stress (PGBS) and negative gate bias stress (NGBS) tests owing to a lower ratio of oxygen vacancies, surface absorbed oxygen molecules, and reduced interface trapping in a-IGZO. Therefore, microwave irradiation is very promising to low-temperature process.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.31 no.1
• /
• pp.50-54
• /
• 2018

In this study, a femtosecond laser pre-annealing technology based on indium zinc oxide (IZO) thin-film transistors (TFTs) was investigated. We demonstrated a stable pre-annealing process to analyze the change in the surface structures of thin-films, and we improved the electrical performance. Furthermore, static and dynamic electrical characteristics of IZO TFTs with n-channel inverters were observed. To investigate the static and dynamic responses of our solution-processed IZO TFTs, simple resistor-load-type inverters were fabricated by connecting a $1-M{\Omega}$ resistor. The femtosecond laser pre-annealing process based on IZO TFTs showed good performance: a field-effect mobility of $3.75cm_2/Vs$, an $I_{on}/I_{off}$ ratio of $1.8{\times}10^5$, a threshold voltage of 1.13 V, and a subthreshold swing of 1.21 V/dec. Our IZO-TFT-based N-MOS inverter performed well at operating voltage, and therefore, is a good candidate for advanced logic circuits and display backplane.

• Journal of Electrical Engineering and Technology
• /
• v.12 no.6
• /
• pp.2353-2358
• /
• 2017

A femtosecond laser pre-annealing process based on indium zinc oxide (IZO) thin-film transistors (TFTs) is fabricated. We demonstrate a stable pre-annealing process to analyze surface structure change of thin films, and we maintain electrical stability and improve electrical performance. Furthermore, dynamic electrical characteristics of the IZO TFTs were investigated. Femtosecond laser pre-annealing process-based IZO TFTs exhibit a field-effect mobility of $3.75cm^2/Vs$, an $I_{on}/I_{off}$ ratio of $1.77{\times}10^5$, a threshold voltage of 1.13 V, and a subthreshold swing of 1.21 V/dec. And the IZO-based inverter shows a fast switching behavior response. From this study, IZO TFTs from using the femtosecond laser annealing technique were found to strongly affect the electrical performance and charge transport dynamics in electronic devices.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2003.11a
• /
• pp.121-126
• /
• 2003

This paper describes the optimum design for journal bearing by using simulated annealing method. Simulated annealing algorithm is an optimum design method to calculate global and local optimum solution. Dynamic characteristics of a journal bearing are calculated by using finite difference method (FDM), and these values are used for the procedure of journal bearing optimization. The objective is to minimize the resonance response (Q factor) of the simple rotor system. Bearing clearance and length to diameter ratio are used as the design variables.

• Journal of KIISE:Computer Systems and Theory
• /
• v.33 no.8
• /
• pp.486-494
• /
• 2006

In this paper, we introduce a new solution for the load balancing problem, an important issue in parallel processing. Our heuristic load balancing technique called MGA effectively combines the benefit of both mean-field annealing (MFA) and genetic algorithms (GA). We compare the proposed MGA algorithm with other mapping algorithms (MFA, GA-l, and GA-2). A multiprocessor mapping algorithm simulation has been developed to measure performance improvement ratio of these algorithms. Our experimental results show that our new technique, the composition of heuristic mapping methods improves performance over the conventional ones, in terms of solution quality with a longer run time.

• Korean Chemical Engineering Research
• /
• v.49 no.5
• /
• pp.600-604
• /
• 2011

Solution processed IGO thin films were prepared using a general chemical solution route by spin coating. The effect of the annealing temperature of IGO thin films based on the ratio of 2:1 of indium to gallium on crystallization was investigated with varying annealing temperature from $300^{\circ}C$ to $600^{\circ}C$. The electronic device characteristic of IGO thin film was investigated. The solution-processed IGO TFTs annealed at 300 and $600^{\circ}C$ in air for 1 h exhibited good electronic performances with field effect mobilities as high as 0.34 and 3.83 $cm^2/V{\cdot}s$, respectively. The on/off ratio of the IGO TFT in this work was $10^5$ with 98% transmittance.

• Proceedings of the KSME Conference
• /
• 2000.04a
• /
• pp.797-802
• /
• 2000

Flow shop scheduling problem involves processing several jobs on common facilities where a setup time Is incurred whenever there is a switch of jobs. Practical aspect of scheduling focuses on finding a near-optimum solution within a feasible time rather than striving for a global optimum. In this paper, a hybrid meta-heuristic method called tabu-genetic algorithm(TGA) is suggested, which combines the genetic algorithm(GA) with tabu list. The experiment shows that the proposed TGA can reach the optimum solution with higher probability than GA or SA(Simulated Annealing) in less time than TS(Tabu Search). It also shows that consideration of setup time becomes more important as the ratio of setup time to processing time increases.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.33 no.2
• /
• pp.93-98
• /
• 2020

We investigated the effect of a post-annealing process using ultraviolet (UV) light on the electrical properties of solution-processed InZnO (IZO) thin-film transistors (TFTs). UV light was irradiated on IZO TFTs for different time periods of 0s, 30s, and 90s. We measured transfer and retention stability curves to evaluate the performance of the fabricated TFTs. In addition, we measured height, amplitude, and phase AFM images to analyze changes in the surface and morphology of the devices. AFM measurements were performed by setting the drive amplitude of the cantilever tip to 47.9 mV in tapping mode, then dividing the device surface into 500 nm × 500 nm. In the case of IZO TFT irradiated with UV for 30s, the electron mobility and I_on/I_off ratio were improved, the threshold voltage was reduced by approximately 2 V, and the subthreshold swing also decreased form 1.34 V/dec to 1.11 V/dec.