• Transactions of the Korean Society of Automotive Engineers
• /
• v.4 no.2
• /
• pp.166-172
• /
• 1996

This paper presents the characteristics of the crankshaft speed fluctuations. To analyze them, the speed waveforms were measured both at the flywheel and at the front end of the engine. The speed waveform measured at the flywheel shows better result than at the front end one, because of the torsional vibration and the auxiliary components. And the patterns of the speed fluctuations are classified into three region, such as low load, middle load and high load region with the variations of the loads. Additionally, as the engine speeds increase and the loads decrease, the analysis of the speed becomes more difficult due to lower variation of the speed. And in all the regions, the main frequency component of the speed fluctuation is firing frequency.

• Proceedings of the KIEE Conference
• /
• 2002.07c
• /
• pp.1640-1643
• /
• 2002

Image sticking, the phenomenon that the previously displayed pattern still remains after the image is changed into different image, is one of the most serious problem in realizing high picture quality. In this paper, we tried characterizing this undesirable feature in terms of the luminance and the intial firing voltage at ramp up time in reset period. It was found that the cell located at the boundary of previous image pattern show low firing voltage and high background luminance. And the results show that the degree of the image sticking is severely affected by discharge duration and the length of the sustain period.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.10 no.6
• /
• pp.927-934
• /
• 1999

A measuring system was integrated for the testing of live EED with continuous wave RF stimulus at low frequency range(1~250 MHz) and pulsed RF stimulus at high frequency range(8~10 GHz). The test system, set-up method and test procedure for the RF sensitivity of EED are described in this paper. The Bruceton method is applied to obtain distribution statistics such as mean firing level, standard deviation of the distribution and confidence levels for various applied firing signals.

• Journal of the Ergonomics Society of Korea
• /
• v.16 no.2
• /
• pp.15-27
• /
• 1997

Brain potential is described using the mesocolumnar activity defined by averaged firings of excitatory and inhibitory neuron of neocortex. Lagrangian is constructed based on SMNI(Statistical Mechanics of Neocortical Interaction) and then Euler Lagrange equation is obtained. Excitatory neuron firing is assumed to be amplitude- modulated dominantly by the sum of two modes of frequency .omega. and 2 .omega. . Time series of this neuron firing is calculated numerically by Euler Lagrangian equation. I .omega. L related to low frequency distribution of power spectrum, I .omega. H hight frequency, and Sd(standard deviation) were introduced for the effective extraction of the dynamic property in the simulated brain potential. The relative behavior of I .omega. L, I .omega. H, and Sd was found by parameters .epsilon. and .gamma. related to nonlinearity and harmonics respectively. Experimental I .omega L, I .omega. H, and Sd were obtained from EEG of human in rest state and of canine in deep sleep state and were compared with theoretical ones.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1997.11a
• /
• pp.510-514
• /
• 1997

The thin film that is electrically conductive and optically transparent is called conductive transparent thin film. ITO(Indium-Tin Oxide) which is a kind of conductive transparent thin film has been widely used in solar cell, transparent electrical heater, selective optical filter, FDP(Flat Display Panel) such as LCD(Liquid Crystal Display), PDP(Plasma Display Panel) and so on. Especially in PDP, ITO films is used as a transparent electrode in order to maintain discharge and decrease consumption power through the improvement of cell structure. In this study, we prepared ITO by reactive r.f. sputtering with indium-tin(Sn 10wt%) alloy target instead of indium-tin oxide target. The ITO films deposited at low temperature 15$0^{\circ}C$ and 8% $O_2$. Partial pressure showed about 3.6 Ω/$\square$. At the end of firing, the resistance of ITO was decreased, the optical transparence was improved above 90%.

• Journal of the Korean Ceramic Society
• /
• v.18 no.3
• /
• pp.192-200
• /
• 1981

This study deals with the low temperature ($25^{\circ}C$-$600^{\circ}C$) properties of Kaolin-Phosphate-water systems. Phosphoric acid, mono aluminum phosphate, mono ammonium phosphate, the mixture of phosphoric acid and mono aluminum phosphate, and the mixture of phosphoric acid and mono ammonium phosphate were used to characterize the M.O.R. of the systems with to quantity of phosphates, curing time, and firing temperature. Firing shrinkage, viscosity, surface tension, DTA, TGA, and X-ray diffraction patterns were also measured in order to investigated the factors of strengthening. The results of this study were summarized as follows: 1. The M.O.R. of kaolin-phosphate systems were stronger than that of Kaolin-water system at room temperature or low temperature($25^{\circ}C$-$600^{\circ}C$). Though it was increased according to the longer curing time, the higher temperature, and the more addition of phosphate, the M.O.R. were decreased in the case of 10 wt% phosphate addition in the system of phosphoric acid, mono aluminum phosphate and phosphoric acid-mono aluminum phosphate. 2. When the concentration of Phosphate was at 4 wt%, the M.O.R. of specimen cured at $25^{\circ}C$ and added to the phosphoric acid was strongest among the specimens in added to the others phosphates. Whereas, when the concentration of phosphate was above 6wt%, the M.O.R. of specimen cured at $25^{\circ}C$ and added to the phosphoric acid mono ammonium phosphate system cured at $25^{\circ}C$ was the strongest. 3. The M.O.R. of the specimen heated, in the temperature range of 15$0^{\circ}C$-1$600^{\circ}C$, and added to the mixture of phosphoric acid-mono aluminum phosphate system or phosphoric acid-mono ammonium phosphate system was stronger than that of specimen added to Phosphoric acid, mono-aluminum Phosphate or mono-ammonium phosphate alone. 4. The bonding force of phosphate binders was more closely related to surface tension than viscosity and it tended to be inversely proportional to surface tension. The bonding force after heating treatment seemed to be caused by the change of structure of phosphate according to heating.

• Journal of the Korean Ceramic Society
• /
• v.29 no.2
• /
• pp.83-88
• /
• 1992

New ceramic substrates firable at low temperature (<1000$^{\circ}C$) were prepared with mixture of alumina and glass powders in CaO-Al2O3-SiO2 system. The substrate of alumina 40 wt% and glass 60 wt%, which was fired between 900∼1000$^{\circ}C$, shows low dielectric constant (5∼8 at 1 MHz), specific gravity of 3.10, relatively low thermal expansion coefficient (5.5${\times}$10-6/$^{\circ}C$ at 40∼500$^{\circ}C$) and excellent surface roughness (0.4∼0.5 ${\mu}$Ra). These properties were thought to be superior to those of conventional Al2O3 ceramic substrates.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.31 no.5
• /
• pp.218-227
• /
• 2021

A thick film NTC thermistor for low temperature co-firing was manufactured by printing and sintering a paste prepared using NTC powder of Mn_1.5Ni_0.4Co_0.9Cu_0.4O₄ composition, lead free frit, and RuO₂ on a 96 % alumina substrate. The effect of frit and RuO₂ on the electrical properties of thick film NTC thermistor was studied. The resistance of the thick film NTC thermistor was higher than that of the bulk phase sintered at the same temperature, but it was found that the negative resistance temperature characteristic appeared more clearly and linearly in the resistance - temperature characteristic. On the other hand, the area resistance decreased as the sintering temperature increased, and the area resistance increased as the amount of frit added increased. The B constant of the thick film NTC thermistor was 3000 K or higher. Among them, it was found that the B constant of the thick film NTC thermistor made of paste with 5 wt% of frit added and sintered at 900℃ showed the highest B constant. Also, it can be seen that the area resistance decreased with the addition of RuO₂, and the change in the area resistance decrease of the thick film NTC thermistor obtained by sintering the paste containing 5 wt% of RuO₂ at 900℃ is the most obvious.

• Korean Journal of Materials Research
• /
• v.24 no.9
• /
• pp.502-507
• /
• 2014

Recently, improvement in the conversion efficiency of silicon-based solar cells has been achieved by decreasing emitter doping concentration, because the lightly doped emitter can effectively prevent the recombination of electrons and holes generated by solar light irradiation. This type of emitter is very thin due to the low doping concentration, thus conductive materials (i.e., silver) used for front electrodes can easily penetrate the emitter during a firing process because of their large diffusivity in silicon. This results in junction leakage currents which might reduce cell efficiencies. In this study, $Al_2O_3$-coated Ag powders were synthesized by an ultrasonic spray pyrolysis method and applied to the conductive materials of the front electrode to control the junction leakage current. The $Al_2O_3$ shell obstructs the Ag diffusion into the emitter during the firing process. The powder is spherical with a core-shell structure and the thickness of the $Al_2O_3$ shell is tens of nanometers. Solar cells were fabricated using pure Ag powders or the $Al_2O_3$-coated Ag powder as front electrode materials, and the conversion efficiency and junction leakage current were compared to investigate the role of the $Al_2O_3$ shell during the firing processes.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.42 no.1
• /
• pp.76-81
• /
• 2014

Military helicopter is exposed to the enemy gun firing due to the low altitude flight of contour flight, hovering & nap of the Earth flight, therefore it has the high possibility to be exploded by the gun firing. Recently the Anti-ballistic requirement is required to get the high level of safety from gun firing in required operational capability. The first military utility helicopter of SURION has the Anti-ballistic requirement and explosion proof. In order to meet the requirement, OBIGGS is adopted for the first time in KUH. It is proven that Anti-Explosion capability is satisfied to requirement for improving vent system which was insufficiently designed in development period and related to Anti-explosion.