• Structural Engineering and Mechanics
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• v.74 no.2
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• pp.243-254
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• 2020

Devastating RC structural failures in the past have identified that the behavior of beam-column joints is more critical and significantly governs the global structural response under seismic loading. The congestion of reinforcement at the beam-column joints with other constructional difficulties has escalated the attention required for strengthening RC beam-column joints. In this context, numerous studies have been carried out in the past, which mainly focused on jacketing the joints with different materials. However, there is no comparative study of different approaches used to strengthen RC beam-column joints, from efficiency and cost perspective. This paper presents a detailed investigation carried out to study the various strengthening schemes of exterior RC beam-column joints, viz., steel fiber reinforcement, carbon fiber reinforced polymer (CFRP) strengthening, steel haunch strengthening, and confining joint reinforcement. The effectiveness of each scheme was evaluated experimentally. These specimens were tested under horizontal loading that produced opening moments on the joints and their behavior was studied with emphasis on strength, displacement ductility, stiffness, and failure mechanism. Special attention was given to the study of crack-width.

• Korean Journal of Optics and Photonics
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• v.32 no.6
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• pp.276-285
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• 2021

This paper reports the study of the line-beam optical system of the laser lift-off (LLO) equipment used in the OLED manufacturing process. To obtain both a long process depth and a narrow width of the line beam, even with the poor M² value of the laser source, the research is focused on the optical system, including the beam transformation unit (BTU). We also propose optical configurations for the super-Gaussian distribution and the fiber-based BTU for the flat-top distribution.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1997.11a
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• pp.473-476
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• 1997

Focused Ar ion laser beam can be utilized to fabricate microstructures on silicon substrate as well as other materials(e.g. such as ceramic). The laser using in this study is an argon ion laser with maximum power of 6 W, wavelength of 514 nm. This laser beam is focused by objectives with a high numerical aperture, a long working distance. We have achieved line width about 1 ${\mu}{\textrm}{m}$ with high scan speed. The resolution for Si machining is determined by the selectivity of the chemical reaction rather than the laser spot size. In this study, we have obtained the maximum etch rate of 434.7 ${\mu}{\textrm}{m}$/sec with high aspect ratio. The characteristics of etched groove was investigated by scanning electron microscope(SEM) and auger electron spectroscopy(AES). It is assumed that the technique using arson ion laser is applicab1e to fabricate microstructures.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1992.05a
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• pp.30-33
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• 1992

This thesis was investigated on ion-induced characteristics in a-$Se_{75}Ge_{25}$ positive and negative resists for focused-ion-beam microlithogaphy. The exposed a-$Se_{75}Ge_{25}$ inorganic thin film shows an increase in optical absorption after exposure to~$10_{16}$ dose of Ga+. The observed shift in the absorption edge toward longer wavelengths is consistent with that in films exposed to band-gap photons(~$10^{21}$photons/cm2). This result may be related with microstructural rearrangements with in the short range of SeGe network. Due to changes in the short range order, the chemical bonding may be affected, which results in increased chemical dissolution in ion-induced film. Also, this resist exhibits good thermal stability because of its high Tg(~$220^{\circ}C$). When focused ion beams are used for direct exposure of resist over a substrate, unwanted implantation of the substrate may be an issue. A possible way to avoid this is to match the thickness of the resist to the range of ions in the resist. Thin aspect is currently under investigation.

• Proceedings of the Materials Research Society of Korea Conference
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• 2008.11a
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• pp.5.1-5.1
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• 2008

• Journal of the KSME
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• v.57 no.1
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• pp.37-41
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• 2017

이 글에서는 대표적인 고에너지 입자빔 기반의 나노가공방법 중에 하나인 집속 이온빔 시스템(focused ion beam system)에 대해 소개하고 이의 응용분야 및 앞으로의 발전 가능성에 대해 논의하고자 한다.

• Proceedings of the Materials Research Society of Korea Conference
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• 1992.05a
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• pp.71-71
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• 1992

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.06a
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• pp.365-366
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• 2008

• Journal of the Mineralogical Society of Korea
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• v.26 no.4
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• pp.325-330
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• 2013

• Proceedings of the Korean Vacuum Society Conference
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• 2008.08a
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• pp.48-48
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• 2008