• Journal of the Korea institute for structural maintenance and inspection
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• v.16 no.5
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• pp.11-18
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• 2012

Deterioration and weakening is advanced in compliance with flowing of time and the change of environment in RC structures. Consequently, strength and serviceability decreases, finally, the life of infrastructure shortens and safety characteristics decreases. Accordingly, in this study, a new method to develop a strengthening method using the vacuum impregnation, which increases durability of the infrastructure occurred the safety reduction due to the performance degradation and increases the life of infrastructure by improving the durability compared to the existing method, was planned. For flexural tests, the maximum strength was a low-end order from high order as follows: (1) vacuum impregnation with 2 fold reinforcement, (2) fiber sheet 2 fold reinforcement, (3) vacuum impregnation with 1 fold reinforcement, (4) fiber sheet 1 fold reinforcement, and (5) nothing. Also, for confirmation results about durability, when the fiber reinforcement is being exposed to the inferior environment, the remaining tensile strength exceeded of 90% or more for all environments. This is because the reinforcement used in this research shows the excellent resistance in severe environment.

• Resources Recycling
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• v.33 no.1
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• pp.37-47
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• 2024

In grouting, the LW method is commonly employed to induce the gelation of cementitious material using water glass, thereby restricting the extent of material injection. Nevertheless, challenges manifest when materials are lost before gelation, particularly in regions with high groundwater flow rates or significant subsurface voids. This study developed a thixotropic grout material using LFS and GGBFS to mitigate material loss during injection, with an assessment of its flow characteristics, durability in marine exposure, strength, and injection properties. The outcomes revealed that the thixotropic grout material exhibited flow ranging from 105 to 143 mm and enhanced strength and durability compared to the LW method. Furthermore, field tests substantiated that applying vibration and impact improved impermeability.

• Journal of the Korea institute for structural maintenance and inspection
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• v.28 no.3
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• pp.59-65
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• 2024

In this study, in order to improve the mechanical properties and durability of asphalt mixtures, a modifier (CSM, Cationized Silicate Modifier) was applied to asphalt to derive optimal mixing ratio conditions. Design of asphalt mixture using modified asphalt binder was conducted, and moisture resistance and dynamic stability were evaluated for optimal mixing conditions. The evaluation results showed that it exceeded the standards stipulated in the relevant guidelines, and as a result of conducting a water permeability test on the optimal mixing condition, it was confirmed that impermeable performance was secured. As a result of examining the noise reduction performance through field test, a noise reduction performance of about 10 dB was secured compared to before paving. It will be necessary to secure reliability through continuous noise generation evaluation in the future.

• Journal of the Korean Society of Propulsion Engineers
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• v.16 no.5
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• pp.20-28
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• 2012

Blending method was applied to increase the performance of hydrogen peroxide which is called green propellant. 90 wt.% hydrogen peroxide was blended with ethanol which is less toxic fuel, and there was no storability decrease due to fuel addition. Inconel X750 and Tophet A showed good compatibility and high heat resistance, and SUS 316L was compatible. $Al_2O_3$, $Y_2O_3$, and $ZrO_2$, were coated on the material to improve heat resistance, and it was proved from endurance test that $Y_2O_3$ coating is not suitable and adhesive strength between coating and material is related with allowable temperature of material. Thruster test was performed to confirm the performance increase by blending method, and chamber temperature was $870^{\circ}C$ which is higher than $760^{\circ}C$ that is adiabatic chamber temperature of 90 wt.% hydrogen peroxide.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.150-158
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• 2011

Blending method was applied to increase the performance of hydrogen peroxide which is called green propellant. 90 wt.% hydrogen peroxide was blended with ethanol which is less toxic fuel, and there was no storability decrease due to fuel addition. Inconel X750 and Tophet A showed good compatibility and high heat resistance, and SUS 316L was compatible. Al2O3, Y2O3, and ZrO2, were coated on the material to improve heat resistance, and it was proved from endurance test that Y2O3 coating is not suitable and adhesive strength between coating and material is related with allowable temperature of material. Thruster test was performed to confirm the performance increase by blending method, and chamber temperature was $870^{\circ}C$ which is higher than $760^{\circ}C$ that is adiabatic chamber temperature of 90 wt.% hydrogen peroxide.

• Journal of the Korean Recycled Construction Resources Institute
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• v.11 no.4
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• pp.493-500
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• 2023

The use of TiO₂ photocatalyst in the production of concrete blocks for the purpose of nitrogen oxide reduction is an issue of controversy due to the conflicting evidence on its effectiveness. Efforts have been made to reduce the level of nitrogen oxides in the environment by using of titanium dioxide (TiO₂). This study examined the effect of incorporating activated carbon into concrete blocks on the reduction of nitrogen oxides released into the atmosphere and the durability of the blocks. The efficiency of photocatalyst was enhanced through the addition of a surrounding conductive substance. The addition of activated carbon resulted in a significant increase in the electrical conductivity of photocatalytic blocks and improved durability. The cement mixture using 5 % TiO₂ and 15 % activated carbon exhibited the optimal mixing ratio for the purpose of nitrogen oxide removal. The effect of the addition of conductive carbon to the photocatalytic blocks was discussed with the results of conductivity, flexural and comprssive strength and nitrogen oxide removal test. The relationship between the addition of conductive carbon to the photocatalytic blocks and its resulting effects have been studied by several tests, including conductivity, flexural and compressive strength, and nitrogen oxide removal.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.277-278
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• 2008

에너지절약에 대한 중요성과 관심으로 효율을 높이고 인버터 구동에 대한 서지내구성이 강화된 전동기용 절연소재의 개발에 관심이 커지고 있다. 최근 나노기술의 발달로 전동기용 에나멜 절연재에 나노입자를 강화하여 성능과 효율의 향상이 크게 개선되고 있다. 본 연구에서는 졸겔 제조법으로 PAI-MCS-A계 나노 하이브리드형 에나멜을 제조하여 기존 수지와의 전기적 특성을 비교 분석하였다. 강화입자로 선택한 나노 MCS 의 조성을 최대 30wt% 범위에서 메트릭스 수지와의 상안정성이 확인되었다. 특히 내아크성, 트래킹 시험에서 우수한 내구성이 나타났으며 이는 전동기용 에나멜 및 전력용 절연코팅용으로 사용이 기대된다. 전기적 절연, 섬락, 누설전류 등에 영향을 미치는 K, Na 값이 기존 다른 연구보고와 유사한 값을 가지고 있는 것을 확인하였다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.497-498
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• 2008

에너지절약에 대한 중요성과 관심으로 효율을 높이고 인버터 구동에 대한 서지내구성이 강화된 전동기용 절연소재의 개발에 관심이 커지고 있다. 최근 나노기술의 발달로 전동기용 에나멜 절연재에 나노입자를 강화하여 성능과 효율의 향상이 크게 개선되고 있다. 본 연구에서는 졸겔 제조법으로 PAI-MCS-A계 나노 하이브리드형 에나멜을 제조하여 기존 수지와의 전기적 특성을 비교 분석하였다. 강화입자로 선택한 나노 MCS의 조성을 최대 30wt% 범위에서 메트릭스 수지와의 상안정성이 확인되었다. 특히 내아크성, 트래킹 시험에서 우수한 내구성이 나타났으며 이는 전동기용 에나멜 및 전력용 절연코팅용으로 사용이 기대된다.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.201.1-201.1
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• 2015

복합 유무기 혼합물을 사용하여 제작한 유기 쌍안정 메모리 소자는 저전력 소비, 고밀도 저장성, 높은 기계적 유연성, 저렴한 가격, 간단한 공정 과정 등의 장점들로 인하여 메모리 분야에서 많은 관심을 받고 있다. 그래핀 옥사이드층을 활용하여 만든 소자에 관한 연구는 이미 다양하게 진행되고 있으나, CdSe/ZnS 양자점을 활용한 메모리 소자에 관한 연구는 아직 많이 연구되고 있지 않다. 본 연구에서는 CdSe/ZnS 양자점을 그래핀 옥사이드에 내포한 유기 쌍안정 메모리 소자를 제작하여 메모리로써의 활용 가능성과 메커니즘을 확인하였다. Indium-tin-oxide (ITO) 기판을 세척한 후, CdSe/ZnS 양자점을 내포한 그래핀 옥사이드 층을 스핀코팅을 이용하여 1000 rpm, 3000 rpm, 1000 rpm으로 각각 3 s, 40 s, 3 s로 코팅한 후 핫플레이트에서 90oC로 30분 동안 열처리 한다. 이렇게 제작된 소자의 실온에서 전류-전압을 측정한 결과 높은 전도도와 낮은 전도도의 비율이 최대 [10]^3까지 나오는 것을 확인할 수 있었다. 투과전자 현미경 및 X선 광전자 분광법 측정결과 그래핀 옥사이드 층과 그 안에 내포된 양자점들의 유무를 확인할 수 있었다. 내구성을 측정한 결과 소자가 안정적이라는 것을 확인할 수 있었다.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.69-69
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• 2010

현대 건축물에서 건물에너지의 손실은 대부분은 창호를 통하여 유출되어지고 있으며 에너지 절감을 위해서는 창호의 단열성을 향상시켜야한다. 저방사(Low Emissivity) 코팅유리는 건축물의 냉난방비용을 절약할 수 있는 대표적인 건축재료로써 외부에서 유입되는 태양광의 가시광선 영역은 높은 투과율을 가지면서 적외선 영역과 겨울철 실내 난방열을 반사하는 특징을 지니는 박막코팅기술이다. 이 코팅유리는 일반적으로 유전체/금속/유전체 다층박막 구조로 되어있으며, 유전체층은 내구성 증진과 금속층의 반사를 낮추어 투과율이 향상된다. 금속층은 적외선영역의 복사에너지를 반사하는 역할을 하며 전도성이 우수한 Ag 또는 Au, Pt 등을 이용하고 있다. Ag의 경우 산화물기판 위에 증착하였을 경우 island 성장을 하고 이들의 합체는 전기적, 광학적 특성에 큰 영향을 미치게 된다. 본 연구에서는 DC-sputtering법으로 제조된 Ag/glass, Ag/Ta/glass 박막을 제조하고 Ta seeding이 Ag의 전기적, 광학적 성질에 미치는 영향을 관찰하였다. 박막의 표면 미세구조는 FE-SEM(Field Emission Scanning Electron Microscope)과 AFM(Atomic Force Microscope)으로, 표면저항은 4 point probe로 분석하였다. 광투과율은 UV-Vis spectroscopy와 FT-IR로 측정하였으며 측정파장범위는 각각 200~1100nm와 1400~2400nm 이다.