• Journal of the Korean Institute of Telematics and Electronics
• /
• v.9 no.5
• /
• pp.34-42
• /
• 1972

Current noise is an important indication of quality in deposited carbon film resistors. Imperfections in the resistive film create high current densities and consequently high current noise. The magnitude of current noise is depend upon many inherent properties of the resistor such as resistive material and others such as processing, fabrication and packing of resistive elements, etc. Performance tests have definitely established a correlation between current noise and electrical performance of carbon film resistors. To interprete the normal distribution of the current noise index for representative groups of resistors would serve as a powerful tool in judging the Quality control and product uniformity by the manufacturer.

• Journal of the Korean Institute of Telematics and Electronics A
• /
• v.31A no.4
• /
• pp.84-91
• /
• 1994

A compact electron cyclotron resonance(ECR) plasma system composed of a microwave generator and a magnet coil was fabricated. A Langmuir single probe was used to investigate the plasma characteristics of the system through I-V measurements. The performance of the compact ECR plasma system was tested for the case of silicon etching reaction with $CF_{4}/O_{2}$(30%) mixed gas. Electron density and etch rate increased to maximum values and then decreased with increasing argon gas pressure, but electron temperature changed in the opposite way. The electron density and the electron temperature of argon gas plasma were 0.85${\times}~5.5{\times}10^{10}cm^{-3}$ and 4.5~6.0 eV, respectively, in the pressure range from $3{\times}10^{4}$ to 0.05Torr. The etch rate reached a maximum value at the position of 2.5cm from the bottom of plasma cavity. Etch rate uniformity was $\pm$6% across 6cm wafer. Anisotropic index was 0.75 at 1.5${\times}10^{-4}$Torr.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2002.08a
• /
• pp.905-909
• /
• 2002

Characteristics of reflective LCDs, which have gained a lot of notice in recent years, rely largely on optical design of circular polarizers and the quarter-wave plates, as a component. Important design includes wavelength dispersion, viewing angle, uniformity of display and matching of refractive index. Our work has contributed to improving performance of reflective LCDs by enhancing the characteristics of polymer film using stretching and optical lamination technologies. To design that offers higher contrast and wider viewing angle, we have discovered that it is necessary to control viewing angle variation of the polarizing axis in order to compensate for the viewing angle of the polarizing film as well as the optical anisotropic properties of liquid crystal. Applying this technology to circular polarizers used for reflective LCDs enables design of wide viewing angle circular polarizers. In order to realize higher contrast for reflective LCDs, it is also necessary to design other optical materials including polarizing films. For design of hybrid optical film, it is particularly necessary to reduce surface reflection and interface reflection. This paper also reports our findings concerning this topic.

• Current Applied Physics
• /
• v.18 no.11
• /
• pp.1436-1440
• /
• 2018

SiN and SiCN film production using plasma-enhanced atomic layer deposition (PE-ALD) is investigated in this study. A developed high-power and high-density multiple inductively coupled plasma (multi-ICP) source is used for a low temperature PE-ALD process. High plasma density and good uniformity are obtained by high power $N_2$ plasma discharge. Silicon nitride films are deposited on a 300-mm wafer using the PE-ALD method at low temperature. To analyze the quality of the SiN and SiCN films, the wet etch rate, refractive index, and growth rate of the thin films are measured. Experiments are performed by changing the applied power and the process temperature ($300-500^{\circ}C$).

• JSTS:Journal of Semiconductor Technology and Science
• /
• v.11 no.3
• /
• pp.135-145
• /
• 2011

Accurate process characterization and optimization are the first step for a successful advanced process control (APC), and they should be followed by continuous monitoring and control in order to run manufacturing processes most efficiently. In this paper, process characterization and recipe optimization methods with multiple outputs are presented in high density plasma-chemical vapor deposition (HDP-CVD) silicon dioxide deposition process. Five controllable process variables of Top $SiH_4$, Bottom $SiH_4$, $O_2$, Top RF Power, and Bottom RF Power, and two responses of interest, such as deposition rate and uniformity, are simultaneously considered employing both statistical response surface methodology (RSM) and neural networks (NNs) based genetic algorithm (GA). Statistically, two phases of experimental design was performed, and the established statistical models were optimized using performance index (PI). Artificial intelligently, NN process model with two outputs were established, and recipe synthesis was performed employing GA. Statistical RSM offers minimum numbers of experiment to build regression models and response surface models, but the analysis of the data need to satisfy underlying assumption and statistical data analysis capability. NN based-GA does not require any underlying assumption for data modeling; however, the selection of the input data for the model establishment is important for accurate model construction. Both statistical and artificial intelligent methods suggest competitive characterization and optimization results in HDP-CVD $SiO_2$ deposition process, and the NN based-GA method showed 26% uniformity improvement with 36% less $SiH_4$ gas usage yielding 20.8 ${\AA}/sec$ deposition rate.

• Imaging Science in Dentistry
• /
• v.47 no.2
• /
• pp.75-86
• /
• 2017

Purpose: The purpose of this study was to apply a newly developed free software program, at low cost and with minimal time, to evaluate the quality of dental and maxillofacial cone-beam computed tomography (CBCT) images. Materials and Methods: A polymethyl methacrylate (PMMA) phantom, CQP-IFBA, was scanned in 3 CBCT units with 7 protocols. A macro program was developed, using the free software ImageJ, to automatically evaluate the image quality parameters. The image quality evaluation was based on 8 parameters: uniformity, the signal-to-noise ratio (SNR), noise, the contrast-to-noise ratio (CNR), spatial resolution, the artifact index, geometric accuracy, and low-contrast resolution. Results: The image uniformity and noise depended on the protocol that was applied. Regarding the CNR, high-density structures were more sensitive to the effect of scanning parameters. There were no significant differences between SNR and CNR in centered and peripheral objects. The geometric accuracy assessment showed that all the distance measurements were lower than the real values. Low-contrast resolution was influenced by the scanning parameters, and the 1-mm rod present in the phantom was not depicted in any of the 3 CBCT units. Smaller voxel sizes presented higher spatial resolution. There were no significant differences among the protocols regarding artifact presence. Conclusion: This software package provided a fast, low-cost, and feasible method for the evaluation of image quality parameters in CBCT.

• Tunnel and Underground Space
• /
• v.26 no.2
• /
• pp.120-130
• /
• 2016

Considering the applicability of Kuz-Ram model, which has been used extensively for predicting rock fragmentation size distribution by blasting, to domestic open-pit limestone mine, a total of 21 blasting tests have been executed at an open-pit limestone mine in eastern Gangwon of South Korea. A comparative analysis of field measured value and Kuz-Ram predicted value showed that there are a considerable amount of error in the predicted values regardless of application of various correction parameters for rock factor and uniformity factor; up to 56.45% in mean fragmentation size and 37.52% in uniformity index. Also the problem of applying different correction parameters has been derived even though a similar blasting pattern has been adopted for a same blasting bench. The authors therefore suggest that Kuz-Ram model needs to be modified for a proper application to domestic open-pit limestone mine.

• Journal of Advanced Marine Engineering and Technology
• /
• v.34 no.3
• /
• pp.360-368
• /
• 2010

A SCR catalytic filter system is used for reducing $NO_x$ and soot emissions simultaneously from diesel combustors. The amount of ammonia (as a reducing agent) must be controlled with the amount of $NO_x$ to obtain an optimal $NO_x$ conversion. Hence, gas mixing between ammonia and exhaust gases is vital to ensure that the SCR catalyst is optimally used. If ammonia mass distribution is not uniform, slip potential will occur in rich concentration areas. At lean areas, on the other hand, the catalyst is not fully active. The better mixing is indicated by the higher uniformity of ammonia mass distribution which is necessary to be considered in SCR catalytic filter system. The ammonia mass distributions are depended on the flow field of fluids. In this study, the velocity field of gaseous flow is investigated to characterize the transport of ammonia in SCR catalytic filter system. The influence of different injection placements on the ammonia mass distribution is also discussed. The results show that the ammonia mass distribution is more uniform for the injector directed radially perpendicular to the main flow of inlet at the gravitational direction than that at the side wall for both laminar (Re = 640) and turbulent flows (Re = 4255). It is also found that the mixing index decreases as increasing the heating temperature in the case of ammonia injected at the side wall.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.24 no.12B
• /
• pp.2335-2341
• /
• 1999

The $2\times32$ coupler consists of Mach-Zehnder interferometer and Y branch coupler. For the designs of this coupler, three dimensional rectangular core waveguide decomposed to two-dimensional structure by the effective index method. To optimize the waveguide structure, the confinement factor was investigated with two-dimensional finite difference Beam Propagation Method. The $2\times32$ coupler fabricated by simulation with height between Mach-Zehnder arms, H=$43.6\mu\textrm{m}$(path difference $0.668\mu\textrm{m}$) was showed best characteristics. In the results of dry etching of core layer, the etching rate of core layer was above 2600${\AA}$/min, the etching ratio of SiO2 to Al mask was 30:1 and the uniformity of etching was $\pm$5%. The maximum insertion loss and the uniformity of $2\times32$ coupler were below 19.2dB, 2dB respectively.

• Proceedings of the Korean Society of Crop Science Conference
• /
• 2017.06a
• /
• pp.213-213
• /
• 2017

High quality seed of proso millet that has high germination percentage, germination speed, and uniformity demanded to increases rates of mechanization in cereal crop cultivation. In order to improve germination characteristics, proso millet seeds were treated with red light, ultrasonication and liquid smoke (LS) solution that generated from hickory wood. All treatments were performed in seed priming solution with 100mM $NH_4NO_3$ at $15^{\circ}C$ for 24hrs under aeration condition. Seeds were exposed under light intensity of 2000 lux for 15m, 30m, 60m, and 120m in priming solution. Ultrasonic treatment was performed at 60%, 80%, and 100% intensity of 21.6 KHz for 5m, 10m, and 20m in priming solution. For LS treatment seed were soaked in 0%, 0.5%, 1.0%, 5.0% and 10.0% of diluted solution with $dH_2O$ or 100mM $NH_4NO_3$ solution. The effect of seed treatment was evaluated with germination percentage (GP), mean germination time (MGT), germination index (GI), germination rate (GR), Germination uniformity (GU) and heath seed percentage (HS). Our results demonstrate that red light (15min) or ultrasonication (21.6kHz, 5min) treatment improved MGT, GI, GR, and GU comparing to untreated control. Importantly, we show that LS treatments have significant effect on the health seedling and germination characteristics. Proso millet seeds that treated with 5% LS solution for 24hrs improves HS up to 97% that similar results obtained in 100mM $NH_4NO_3$ priming for 24hrs. The combined treatment with LS solution and 100mM $NH_4NO_3$ priming were not effective in all treatments. Our results demonstrate that treating seeds with LS or 100mM $NH_4NO_3$ priming or ultrasonication improves germination characteristics. The methods described here will help advance research using this species by increasing the germination performance at which successive seed pellet process.