• Proceedings of the Korean Vacuum Society Conference
• /
• 2014.02a
• /
• pp.494.2-494.2
• /
• 2014

실리콘 태양전지는 현재 다른 태양전지 셀에 비해서 높은 변환효율 및 우수한 안정성을 가지고 있으며, 상대적으로 가격도 저렴하여 상용으로 판매되는 대다수의 모듈이 실리콘 태양전지를 사용하고 있다. 이러한 태양전지 모듈이 25년 이상 보증을 위해서는 장기 열화메카니즘 연구가 중요시 되고 있다. 따라서 태양전지 모듈을 가속열화하여 높은 내구성을 보유하고 있는지 연구가 필요하다. 본 연구에서는 결정질 실리콘 태양전지 모듈의 옥외실증 시험을 통해 일사량, 기온, 습도, 풍향, 풍속과 같은 환경인자에 따른 모듈의 성능 비교를 통해 모듈의 열화요인에 대하여 분석하였다. MYPGT (Maximal Yield Power Generation Tracking)를 활용하여 모듈의 특성을 정밀하게 측정하며, 빠른 대기환경의 변화에 따른 매시간 태양전지의 전류-전압 특성을 지속적으로 정확하게 측정함으로써 대기환경에서 받는 영향에 대해 분석하였다.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.23 no.4
• /
• pp.145-151
• /
• 2019

The Physical performance of use materials was evaluated to improve durability of fast-paced repair mortar used at rapid construction sites. The fastening performance and basic performance were evaluated by substituting ferronickel grinding slag residues, rapid settlement, and EVA-based polymer for mortar. As a result, the compressive strength, flexural strength and adhesion strength were increased due to the use of FS Fine Aggregate and RS Fine Aggregate. The chloride ion promotion test of fast-polymer mortar kept the chloride inhibitory performance from 7 days to 28 days when fNS was used less than 50%. Durability degradation due to the use of FS Fine Aggregate and RS Fine Aggregate has not been found, and it is believed that further consideration of economic and long-term durability will be required for use as alternative Aggregate for construction and civil engineering.

• Journal of the Korean Institute of Gas
• /
• v.28 no.1
• /
• pp.65-72
• /
• 2024

Green Hydrogen demonstration complex is under conduction in Jeju island which is rich in renewable energy resources and will produces green hydrogen using a water electrolysis systems. In order to check durability of long-term operation, AST(accelerated stress test) was applied and the power pattern based on Jeju Island's wind power was applied. After 800 hours of repeated application of low current and high current, the performance of the PEM water electrolysis cell was reduced by up to 10% and by about 5.5% in operating conditions. As the result of impedance analysis, it can be seen that the electrode polarization resistance greatly increased than ohmic polarization resistance. In addition, when the durability evaluation was conducted by applying the wind power pattern of Jeju Island, the performance of the PEM water electrolysis cell showed up to 1.6% and a decrease of less than 1% in operating conditions. As a result of the impedance, it can be seen that the change of ohmic resistance and electrode polarization resistance is small.

• Information Display
• /
• v.23 no.4
• /
• pp.12-21
• /
• 2022

반도체 기반 양자점 (QD)소재와 CsPbX3 (X=Cl, Br, I)기반 perovskite 양자점 또는 나노결정 소재(PNC)는 매우 우수한 양자효율과 좁은 발광 선폭으로 고색재현성 디스플레이 색변환 소재 또는 발광 소재로서 각광을 받고 있다. 그러나, 기존 화학적 합성법을 통해 제조되는 QD 및 PNC 소재는 취약한 열 및 화학적 안정성으로 인해 장기 내구성의 개선이 요구된다. 이들 QD 및 PNC 소재는 모두 완전 무기 소재인 산화물 기반 유리 소재내에 생성이 가능하며, 이를 통해 장기 내구성을 근본적으로 개선할 수 있다. 반도체 기반 QD 함유 유리소재 (QDEG)의 경우, 유리 내 core/shell 구조를 가진 QD의 생성으로 양자효율의 향상이 가능했으나, 콜로이드 기반 양자점 (cQD)과 달리 다중 shell의 형성이 어려워 양자효율이 제한되고, 발광 선폭이 넓어 고색재현성 디스플레이용 색변환 소재로 적용되기에는 아직 한계가 있다. 한편, Perovskite 양자점 (또는 나노결정) 함유 유리소재 (PNEG) 소재는 QDEG과 달리 콜로이드 기반의 PNC (c-PNC)가 가지는 우수한 양자효율과 20 nm 수준의 좁은 선폭을 유리 내에서도 가지며, c-PNC 대비 열적, 화학적 및 광학적 안정성이 획기적으로 향상되어 실질적인 응용 가능성을 높이고 있다. 특히, 일반적인 용융-급랭법으로 제조하여 대량생산에 용이하고, 분말 또는 판상 등 다양한 형태로의 제작이 가능한 장점이 있다. 현재까지 제조된 PNEG의 최대 PL-QY는 450 nm 여기 시 녹색 및 적색에서 약 60% 수준이며, Al₂O₃ 분말을 이용할 경우 최대 80% 수준까지 달성이 가능하다. 또한, PNEG과 blue LED를 이용하여 백색 LED를 구현할 경우 color filter를 적용하지 않을 때, NTSC 대비 최대 약 130 % 수준의 높은 색재현 영역을 보여 주고 있으며, 실제 LCD용 BLU로 적용 시 기존 상용 c-QD 소재와 동등 이상의 색재현 영역을 보이고 있어, 실질적인 응용 가능성이 매우 높음을 확인하였다. PNEG의 상업적인 응용을 위해서는 몇 가지 추가적인 연구 개발이 필요하다. 기존 c-QD 또는 c-PNC는 나노 수준 크기의 입자가 액상에 분산된 형태로 입도 제어가 용이하나, PNEG의 경우 분말 제조 시 유리 형성 후 분쇄를 통해 제조되며, 입도가 대개 수십 ㎛ 이하로 작아질 경우 PL-QY가 저하되어, 향후 잉크젯 공정 응용을 위해서는 고효율의 분말 제조공정 개발이 필요하다. 또한, 유리 소재의 경우 절연체로서 기존 QD 소재 대비 electro-luminescence(EL) 소자의 활성층으로 사용하는데 제약이 있어 PNEG을 이용한 EL 소자 제작에 대한 연구도 필요하다. 마지막으로, 기존 c-PNC 소재와 같이 Pb가 함유되지 않은 PNEG 소재의 개발이 선결되어야 할 것으로 판단된다. 이와 같은 해결 과제들에도 불구하고, PNEG 소재는 기존 c-QD 소재 대비 매우 우수한 안정성을 기반으로 고품위 고색재현 디스플레이용 색변환 소재로서 다양한 응용에 활용될 수 있을 것으로 기대된다.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.18 no.3
• /
• pp.167-177
• /
• 2014

New technologies for water purification are continuously emerging to address global water quality problems, and one such technology involves advanced hermetic water purification facilities made by concrete that utilize ozone treatment processes. Better knowledge about surface deterioration of epoxy coating exposed to ozone treatment is needed as a foundation for development of improved methods and materials in the future. This study utilized atomic force microscopy (AFM), nanoindentation methods, and existing indirect methods such as visual observation, changes in mass, surface observation and chrominance analysis, to evaluate epoxy water-resistance and anti-corrosiveness. This study considered six different epoxy formulations to assess typical degradation characteristics of epoxy surfaces with regard to water-resistance/anti-corrosiveness. AFM and nanoindentation techniques emerged as promising direct methods with potential to provide quantitative measures of surface quality that are improvements upon existing indirect methods. The experiments also confirmed that some of the epoxy-coatings were severely iMPacted by ozone exposure, and thus the results demonstrate that concern about such deterioration is justified.

• Journal of the Korean Society for Railway
• /
• v.17 no.4
• /
• pp.260-269
• /
• 2014

Transition tracks are an alternative for enhancing the long-term serviceability and durability of concrete track components in railway bridges. The goal of this paper is to investigate the structural behavior for transition track systems of railway bridge deck ends. In this study, the structural behavior of transition tracks such as the variations in static, dynamic, and fatigue behaviors and dynamic properties (natural frequency and damping ratio) are assessed and compared through performing loading tests and finite element analyses using actual vehicle impact loadings. As a result, it is found that the structural behavior of the transition track system is expected to satisfy the actual vehicle impact loading, and the variation in the neutral axis and dynamic characteristics are not affected by the fatigue loading. Therefore, it is inferred that the structural capacity and long-term durability of the transition track system is proven.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2008.11a
• /
• pp.533-536
• /
• 2008

This study is the application of phosphate magnesia cement for solidification of soils. The object of the study is the application of the pavment of the farm roads. The new pavement method must be environmental, ecologic and durable. So, for solidification of farm road's soil, we use magnesia cement as quick setting, high strength materials. At magnesia phosphate cement, mixing ratio of mono ammonium phosphate and magnesia is 4:6 and w/b is 50 wt%, it show 14 MPa of compressive strength, and high hydration heat. Solidified soils that mixing ratios of magnesia cement and soil are 4:6 and 5:5 have very high durability for freezing and thawing.

• Journal of the Korea Concrete Institute
• /
• v.21 no.5
• /
• pp.639-647
• /
• 2009

In order to evaluate the durability of reinforced concrete structures under chloride attack from sea water and frost damage, it is important to analyze both the microstructural characteristics of concrete and its diffusion resistance of concrete against chloride ingress. In this study, a relation between micro-pore structures of concrete obtained by the Mercury Intrusion Porosimetry and accelerated chloride diffusivity as well as long term chloride diffusivity were studied for ground granulated blast furnace slag(GGBS) concrete. Different water-cement ratio of 40, 45, 50% and different unit cement concrete of 300, 350, 400 or 450 kg/$m^3$ of the GGBS concrete along with OPC concrete were used and freeze and thawing, and the change in diffusivity and microstructure were observed for both GGBS concrete and damaged GGBS concrete due to rapid freezing and thawing.

• Journal of the Society of Disaster Information
• /
• v.9 no.3
• /
• pp.315-323
• /
• 2013

Recently, FRB is being used more as reinforcement of RC beam thanks to its material advantages in construction industry. The external attachment reinforcement of FRP is a construction method with advantages such as high strength, stiffness, excellent durability and construction practicability, despite of its weight. However, the reinforcement has a disadvantage to cause damage on permanent structure as its structure is water-tight by low water permeability reinforcement, preventing water from draining outside. The study attempted flexural failure test for GP of which material properties are equally same as the existing FRP and that with permeability, shows good binding with the concrete structure, durable performance and durability, comparably analyzing the improvement of durability and ductility according to changes of fiber contents of composite strip.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.28 no.3A
• /
• pp.407-415
• /
• 2008

Hydration reaction of Free-CaO is thought to be the main reason of expansion failure of slag. A lot of research institutions are conducting studies on solutions to this problem, and moreover it has been carried out how to make use of aggregates for concrete. While studies covering wide rage of blast furnace slag have been accomplished in the country, studies on steelmaking slag are insufficient. Therefore, this study aimed at analyzing basic physical properties of electric arc furnace oxidizing slag, which is the main material, and furthermore it focused on how to make use of aggregates for concrete examining chemical mechanism, which can be put to practical use. To address this issue, components of electric arc furnace oxidizing slag were analyzed with measurement of physical properties, followed by long-term strength and detailed durability analysis, which can evaluate the appropriateness of application of cement concrete. Besides the environmental conservation and recycling which can be obtained by application of industry byproducts, commercializing of electric arc furnace oxidizing slag as fine aggregates for cement concrete are expected.