• Proceedings of the KIEE Conference
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• 2006.07c
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• pp.1623-1624
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• 2006

It is a paper for design, manufacture and estimation of industry inkjet head. Simulations for Actuator, Ink flow and Ejection are executed for securing design ability. Relations between droplet and properties of ink are explained closely through simulation for nozzle. Actually, two silicon plates are made by dry and wet etching and directly bonded. PZT materials is attached on the bended ink flow part and cut to $540{\mu}m$ interval by dicing saw. Actuator was seen variation within 10% between simulation and actual head. Through the ejection estimation, it is shown that stabilized driving voltages change according to viscosity and surface tension of metal ink. Using the metal ink of viscosity of 4.8 cps and surface tension of 0.025 N/m, it is possible to eject the stable droplets with 5m/s, 20 pl, 5 kHz.

• Journal of Applied Reliability
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• v.17 no.4
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• pp.296-304
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• 2017

Purpose: Recent weapon systems in defense have increased the complexity and importance of software when developing multifunctional equipment. In this study, we analyze the accuracy of the proposed software reliability model when applied to weapon systems. Methods: Determine the similarity between software reliability analysis results (prediction/estimation) utilizing data from developing weapon systems and system failures data during operation of weapon systems. Results: In case of a software reliability prediction model, the predicted failure rate was higher than the actual failure rate, and the estimation model was consistent with actual failure history data. Conclusion: The software prediction model needs to adjust the variables that are appropriate for the domestic weapon system environment. As the reliability of software is increasingly important in the defense industry, continuous efforts are needed to ensure accurate reliability analysis in the development of weapon systems.

• Corrosion Science and Technology
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• v.23 no.2
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• pp.121-130
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• 2024

In recent years, Zn-Al-Mg alloy galvanized steel sheets have been widely used as coated steel sheets to support social capital in the infrastructure field. A feature of Zn-Al-Mg alloy-coated steel sheets is that they provide a better corrosion protection period than Zn-coated steel sheets. In this study, the corrosion resistance of a new Zn-Al-Mg alloy-coated steel sheet was investigated and compared to that of conventional commercially available coated steel sheets. The investigation confirmed that increasing the Mg concentration in the Zn-Al-Mg-coated steel sheet improved corrosion resistance, which was more than 10 times that of the galvanized steel sheet specified in JIS G 3302. The study findings also confirmed that the corrosion resistance reached more than twice that of the coated steel sheet specified in JIS G 3323. If such galvanized steel sheets are applied to social infrastructures that are exposed to severely corrosive environments, the service life of the infrastructure might be extended.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1542-1543
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• 2007

This paper presents the effect of driving waveform for piezoelectric bend mode inkjet printhead with optimized mechanical design. Experimental and theoretical studies on the applied driving waveform versus jetting characteristics were performed. The inkjet head has been designed to maximize the droplet velocity, minimize voltage response of the actuator and optimize the firing frequency to eject ink droplet. The head design was carried out by using mechanical simulation. The printhead has been fabricated with Si(100) and SOI wafers by MEMS process and silicon direct bonding method. To investigate how performance of the piezoelectric ceramic actuator influences on droplet diameter and droplet velocity, the method of stroboscopy was used. Using the water based ink of viscosity of 11.8 cps and surface tension of 0.025N/m, it is possible to eject stable droplets through 64 nozzles average velocity of 4.05 m/s with standard deviation of 0.06 m/s and average diameter of $29.2\;{\mu}m$ with standard variation of $0.5\;{\mu}m$.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.04a
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• pp.54-54
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• 2006

• Proceedings of the KIEE Conference
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• 1999.07g
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• pp.3123-3125
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• 1999

광기록 저장매체의 기록밀도가 더욱 올라가면서 현재 콤팩트디스크나 DVD(Digital Versatile Disc)에 사용되고 있는 d=2인 코드보다는 검출성능이 좋은 d=1인 코드에 대한 관심이 점점 높아지고 있다. 광기록 저장매체에 사용할 수 있는 코드가 갖추어야할 중요한 제한조건으로는 코드열의 전력밀도가 저주파에서 충분히 억압될 수 있어야 한다는 것이다. 광자기디스크나 하드디스크에서 사용된 적이 있는 (1.7)코드는 코드자체로서 DC억압능력을 갖고있지 않다. DC를 억압시키기 위해 보통 부가비트를 일정간격으로 삽입하거나 싱크를 이용하게 되는데 이와 같은 방법으로는 충분한 DC억압이 어렵거나 기록밀도를 올리는데 불리한 원인이 된다. 본 논문에서는 코드열 자체로서 DC억압능력을 갖고 있는 코드워드의 생성방식과 변조 알고리즘을 RLL(1,8)인 경우를 예로 제시하였다. 또한 본 논문에서 제시한 코드의 성능에 대한 검증으로 기존의 RLL(1,8)코드(1)와 본 논문에서 제시한 코드에 4%이하의 부가비트를 삽입하여 DC억압을 수행한 뒤 동일한 기록밀도에서 DC억압성능을 비교하였을 때 저주파 대역에서 $1^{\sim}5dB$이상의 개선효과가 있었음을 확인하였다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.05a
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• pp.267-268
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• 2012

• Proceedings of the Optical Society of Korea Conference
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• 2004.02a
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• pp.248-251
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• 2004

근접장 초해상 기술 중 대표적인 Super-RENS (Super Resolution Near Field Structure) 기술을 이용하여 25GB 용량의 BD(Blu-ray Disc) 다음 세대로 예상되는 100 ${\sim}$ 200 GB 용량의 Media 및 기록 재생 기기를 개발하고자 한다. 현재까지 이 기술의 어려움이었던 Stability 특성은 10만회 재생 내구성을 확인하엿고 CNR (신호 대 잡음 비) 특성은 50 nm 미세 마크에 대하여 40 dB의 특성을 확보 하였다. 이 특성은 대략 75 GB에 대응하는 것으로 BD System을 그대로 사용하면서 달성한 세계 최고의 기록 밀도로 평가된다. 향후 과제는 Jitter. Error Rate등 실제 신호 특성의 확보로서, 이의 확보를 통하여 기술의 상품화 가능성이 확인될 것이다.

• Journal of the Korean Magnetics Society
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• v.5 no.5
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• pp.819-823
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• 1995

The oil-based magnetic fluids were sysnthesized using ultra-fine $Fe_{3}O_{4}$ powder dispersed in hydrocarbon oil. To synthesize ultra-fine $Fe_{3}O_{4}$, we carried out the experiments varying the pH of reacting medium and the initial concentration of $Fe^{2+}$. We also investigated the amount of oleic acid to obtain a stable dispersion and the proper base oil of MF for loudspeaker application. The limits of adsorbed amount of oleic acid on the $Fe_{3}O_{4}$ surface were approximately 35~40 percents of the total magnetite weight. As the $Fe_{3}O_{4}$ content increased from 0.1g/cc to 0.6g/cc, the viscosity of oil-based magnetic fluid increased from 1,063cP to 1,828cP, and its saturation magnetization at 10kOe increased from 66G to 242G. When we tested the MF sample to a commercial speaker, improvements were noted.

• Proceedings of the KIEE Conference
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• 1992.07b
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• pp.886-890
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• 1992

Recent investigations have been made on polymer Insulators of various types. The findings are related to experience on operational lines in foreign countries, design concepts, materials and tests about outdoor properties. Over last decade improvements have been occured in the design and construction techniques of polymer insulators. For transmission and distribution lines, it may be advantageous or even necessary to replace, the conventional porcelain or tempered glass insulators by lighter polymer insulators which have better mechanical properties.