• 청정기술
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• 제27권1호
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• pp.85-92
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• 2021

태양에너지를 활용하여 전력을 생산하는 시스템인 Solar water battery는 광전기화학전지와 에너지저장시스템을 결합한 것으로 추가적인 외부 전압 없이 태양에너지의 전환과 저장을 동시에 할 수 있다. Solar water battery는 광전극, 저장전극 그리고 상대전극으로 구성되어 있고, 이들의 선택과 조합은 시스템의 성능과 효율에 있어 중요한 역할을 한다. 본 연구에서는 Solar water battery의 구성요소들을 변화시켜 시스템에 미치는 영향을 알고자 하였다. 상대전극이 방전 시 미치는 영향, 광전극과 저장전극의 전극 재료, 전해질의 종류에 따른 태양에너지 전환 효율과 저장 용량에 미치는 영향에 대해 연구하였다. 이들의 최적화된 구성(TiO2 : NaFe-PB : Pt foil)에서 15시간동안의 광조사 후의 방전 용량이 72.393 mAh g-1으로 시스템 구성 조건에 따라 광전환/저장 효율이 크게 영향을 받음을 확인 할 수 있었다. 또한, 유기 오염물질을 광전극 반응조내 전해질에 첨가하여 광전하를 효율적으로 분리시킴으로써 광전류 증가시켰으며, 이로 인해 저장용량이 향상되고, 동시에 오염물질도 분해시킬 수 있음을 확인하였다. 이처럼 Solar water battery는 추가적인 외부 전압이 필요없는 새로운 친환경 태양에너지 전환/저장 시스템이며, 나아가 수처리에도 활용할 수 있을 것으로 기대된다.

• 디지털정책학회지
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• 제1권2호
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• pp.9-15
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• 2022

2011년, 세계경제포럼(The World Economic Forum)은 물-에너지-식량을 세계 3대 위험군에 포함했다. 물-에너지-식량은 국가의 발전 전략과 국민의 삶과 관계된다. 본 연구에서는 SBM-Malmquist 지수를 기반으로 중국의 2011-2020년 물-에너지-식량 종합 이용 효율성을 계산한다. 측정 결과를 살펴보면, 중국 전체 물-에너지-식량의 종합 이용은 효율성이 낮으나 상승세를 보였다. 전국적으로 물-에너지-식량 종합 이용 효율성은 뚜렷한 차별성이 존재하며 전반적으로 동부> 중부> 서부의 지리적 분포 구도를 보인다. 전국에 Beijing과 Shanghai만 진정한 유효에 이르고 기타 각 성의 투입과 산출 사이에는 모두 비효율 상태가 존재한다. 물-에너지-식량 종합 이용 효율성의 Malmquist 지수는 1.136으로 상승세를 보이며 기술효율과 기술진보를 통해 중국의 물-에너지-식량 종합 이용 효율성의 향상을 이끌고 있다. 하루빨리 물-에너지-식량 문제에 있어 전략적높이를 끌어올려 그 발전에 대한 정책적 지원을 해야 한다. 각 지역은 지역 간 조율기구를 설립해야 하며 각 성의 식량 생산량, 수자원 분포 등 문제에 따라 맞춤형 조치를 제정해 경제가 조방형 발전에서 녹색 발전으로 전환되도록 조속히 추진해야 한다.

• 한국지열·수열에너지학회논문집
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• 제3권2호
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• pp.17-23
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• 2007

Geothermal energy is used in various forms, such as power generation, direct use, and geothermal heat pumps. High temperature geothermal energy sources have been used for power generation for more than a century. Recent technical advances in power generation equipments make relatively low temperature geothermal energy to be available for power generation. In these applications, lower temperature geothermal energy source makes smaller difference between condensing water temperature and it. Various condensing water temperatures were investigated in analyzing its influence on power generation performance. Condensing water temperature of organic Rankine cycle imposed greater influence on power generation and its performance in lower temperature geothermal power generation.

• 태양에너지
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• 제12권3호
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• pp.84-93
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• 1992

본 연구에서는 꽃저장용 냉장시스템 등에 태양열을 이용할 수 있는 난방시스템을 조합하여 충분한 양의 고온을 확득하여 주택의 난방을 가능케 하는 시스템을 설계, 제작했다. 압축기는 기존의 압축기 냉각방식을 공냉식에서 수냉식으로 전환시켜 적절한 냉각효과의 증대는 물론 냉열을 회수하여 고온의 온수를 빠른 시간 내에 획득할 수 있는 시스템을 개발했다.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part2
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• pp.1122-1123
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• 2006

Mn-Fe oxide and Mn-Fe oxide/$ZrO_2$(50wt%/50wt%) were prepared by ball milling method. XRD data of the prepared samples revealed that hematite and ferrite phase coexisted. Water splitting at 1273K, after thermal reduction at 1573K, was performed 4 times for the samples. Hydrogen production amount was analyzed by GC with TCD detector. Water splitting capacity of Mn-Fe oxide was improved by ball milling with $ZrO_2$.

• Tribology and Lubricants
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• 제35권6호
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• pp.350-355
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• 2019

Surface energy is an important factor in determining the performance of application components in terms of preventing adhesion failure between thin films. In this regard, numerous attempts have been made to acquire the desired surface energy through chemical treatment or by using micro/nanostructures. However, such approaches are expected to provide extreme values of surface energy, which may not be suitable in achieving the enhanced performance of applications. In this study, we propose a method to control surface energy by using bilayer metallic film heterostructures. We measure the water contact angle of incompatible (Ni/Ag) and compatible (Zn/Ag) metal pairs under several experimental factors, including thickness, time, and temperature. Furthermore, we conduct Auger electron spectroscopy measurements to investigate the atomic concentration with respect to depth after the change in the water contact angle. The experimental results reveal that three parameters, namely, compatibility, film thickness, and environmental temperature, are major factors in controlling the water contact angle. Thus, we experimentally demonstrate that controlling these three parameters can provide the approximate desired water contact angle. This result is expected to aid in the performance enhancement of a wide range of application components, where control of surface energy is required.

• Bulletin of the Korean Chemical Society
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• 제30권5호
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• pp.1067-1070
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• 2009

We studied change in water contact angle on $TiO_2$ surfaces upon high-energy electron-beam treatment. Depending on conditions of e-beam exposures, surface OH-content could be increased or decreased. In contrast, water contact angle continuously decreased with increasing e-beam exposure and energy, i.e. change in the water contact angle cannot be rationalized in terms of the overall change in the surfacestructure of carbon-contaminated $TiO_2$. In the C 1s spectra, we found that the C-O and C=O contents gradually increased with increasing e-beam energy, suggesting that the change in the surface structure of carbon layers can be important for understanding of the wettability change. Our results imply that the degree of oxidation of carbon impurity layers on oxide surfaces should be considered, in order to fully understand the change in the oxide surface wettability.

• 한국지열·수열에너지학회논문집
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• 제8권4호
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• pp.17-23
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• 2012

Due to reinforcement of international environment regulation and high oil prices, interest in renewable energy is growing. Countries participating in UNFCCC are continuously putting efforts in reducing greenhouse gas after enforcing Kyoto Protocol into effect on Feb, 2005. Energy used in buildings, which relies heavily on fossil fuel accounts for about 24% of total energy consumption. In this study, air, geothermal and water source heat pump systems for an 322 $m^2$ auditorium in an office building is simulated using TRNSYS version 17 for comparing energy consumptions. The results show that energy consumptions of air, geothermal and water source heat pumps are 14,485, 10,249, and 10,405 kWh, respectively. Annual equal payments which consider both initial and running costs become 5,734,521, 6,403,257 and 5,596,058 Won. Thus, water source heat pump is the best economical choice.

• Nuclear Engineering and Technology
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• 제53권8호
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• pp.2570-2575
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• 2021

The exchange behaviors of hydrogen isotopes between protonated lithium metal compounds and deuterated water or tritiated water were investigated. The various protonated lithium metal compounds were prepared by acid treatment of lithium metal compounds with different crystal structures and metal compositions. The protonated lithium metal compounds could more effectively reduce the deuterium concentration in water compared with the corresponding pristine lithium metal compounds. The H⁺ in the protonated lithium metal compounds was speculated to be more readily exchangeable with hydrons in the aqueous solution compared with Li⁺ in the pristine lithium metal compounds, and the exchanged heavier isotopes were speculated to be more stably retained in the crystal structure compared with the light protons. When the tritiated water (157.7 kBq/kg) was reacted with the protonated lithium metal compounds, the protonated lithium manganese nickel cobalt oxide was found to adsorb and retain twice as much tritium (163.9 Bq/g) as the protonated lithium manganese oxide (69.9 Bq/g) and the protonated lithium cobalt oxide (75.1 Bq/g) in the equilibrium state.

• 한국수소및신에너지학회논문집
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• 제34권5호
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• pp.389-397
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• 2023

This study compares domestic and foreign research on renewable energy-based water electrolysis clean hydrogen. Domestic studies from 2010 to 2023 focused on technological efficiency, energy efficiency, and system efficiency, with few analyzing infrastructure and technology trends. Overseas research initially focused on technological efficiency and stability, but has since shifted to economic and environmental impact, policy effectiveness, industry-university-research cooperation, and sustainability. To improve water electrolysis technology production, this study suggests prioritizing technology stability over efficiency, resolving government regulations and resident acceptance issues, promoting industry-university-institute cooperation for rapid commercialization of research results, and developing a strategy for sustainable development of renewable energy-based water electrolysis technology.