• 신재생에너지
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• 제20권1호
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• pp.110-115
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• 2024

Global sustainable energy needs and carbon neutrality goals make hydrogen a key future energy source. South Korea and Japan lead with proactive hydrogen policies, including South Korea's Hydrogen Law and Japan's strategy updates aiming for a hydrogen-centric society by 2050. A notable advance is the solar thermal chemical water-splitting cycle for green hydrogen production, spotlighted by Korea Institute of Energy Research (KIER) and Niigata University's joint initiative. This method uses solar energy to split water into hydrogen and oxygen, offering a carbon-neutral hydrogen production route. The study focuses on international collaboration in solar energy for thermochemical water-splitting and E-fuel production, highlighting breakthroughs in catalyst and reactor design to enhance solar thermal technology's commercial viability for sustainable fuel production. Collaborations, like ARENA in Australia, target global carbon emission reduction and energy system sustainability, contributing to a cleaner, sustainable energy future.

• 한국수소및신에너지학회논문집
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• 제19권2호
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• pp.132-138
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• 2008

금속산화물의 열화학싸이클에 의한 수소생산 소재중 안정성이 우수하고 물분해 수소생산능이 비교적 우수한 $NiFe_2O_4$를 합성하여 열화학수소생산공정 적용시 최적화의 조건에 대하여 검토하였다. 합성한 $NiFe_2O_4$는 격자상수가 $8.34\;{\AA}$이었고, 뫼스바우어에 의해 구조는 Ni이 페라이트 구조인 $AB_2O$의 B위치에 주로 위치하는, A 및 B의 상대적 흡수강도가 57.9:42.1인 역스피넬구조를 보이고 있다. 이러한 구조의 $NiFe_2O_4$의 열적환원은 $610^{\circ}C$부터 시작하여 $1200^{\circ}C$에 이르는 동안 약 1.1 wt%의 무게감소가 관찰된다. 물에 의한 산화과정에서 수소가 발생하게 되는데, $1200^{\circ}C$이하의 환원온도에서 가능한 수소생산량은 약 $0.45\;cm^3/g{\codt}cycle$ 이었다. 산화 환원의 반복과정에서 $NiFe_2O_4$의 XRD에 의한 구조변화는 관찰되지 않아 매우 안정한 구조를 갖는다는 것을 보여주었다. 수소생산을 위한 무게당 싸이클당 수소생산양은 산화 환원과정의 온도범위가 가장 중요하였고 물의 접촉시간은 중요한 요소가 되지 않았다. 열적 환원과정에서 많은 양의 수소생산성능을 보이기 위해서는 $1200^{\circ}C$이상의 고온을 필요로 하는 것을 보여주었다.

• Korean Chemical Engineering Research
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• 제54권4호
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• pp.479-486
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• 2016

순산소 전로 후드의 일산화탄소와 열회수를 위해서는 고효율의 증기를 발생시키는 증기드럼의 장착이 필요하다. 그러나 제선 제강공정에서 증기발생은 간헐적이거나 주기적인 산소 취입공정기간에 제한적이다. 따라서, 증기드럼은 전로의 주기에 따른 산소의 취련기간 동안 효율적으로 증기를 발생시키도록 최적 설계되어야 한다. 따라서 본 연구에서는 다양한 운전조건 및 기하학적 형상변화가 증기드럼 내의 열유동 특성과 성능에 미치는 효과를 예측할 수 있는 3차원 전산유체역학 모델을 제안하였다. 본 모델은 유체유동 및 열전달 뿐만 아니라 계면유동에서의 증발 및 응축을 유한체적법을 사용하여 고려하였다. 본 모델의 예측성능을 검증하기 위하여 실험에서 구한 증기발생량과 비교하였으며 3.2%의 상대오차를 보였다.

• 청정기술
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• 제24권1호
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• pp.9-14
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• 2018

본 연구에서는 TiN-Zr 수소분리막의 제조 공정에 대한 환경 영향 특성을 분석하기 위해 물질전과정평가를 수행하였다. Material Life Cycle Assessment (MLCA)의 소프트웨어로는 Gabi를 사용하였다. 이를 통하여 각 공정에서 미치는 영향과 특성화 별 환경영향평가를 수행하였다. 졸겔법에 의해 전구체 TiN을 합성하고 볼밀법을 이용하여 지르코늄을 코팅하였다. 이를 CIP, HPS에 의해 디스크 형으로 제작하였고 주사전자현미경(scanning electron microscopy, SEM), 에너지분산형 분광분석법(energy dispersive X-ray spectroscopy, EDS), X-선 회절분석기(X-ray diffraction, XRD), 열중량분석(thermo gravimetry/differential thermal analysis, TG/DTA), 비표면적분석(Brunauer, Emmett, Teller, BET) 및 가스 크로마토그래프 시스템(gas chromatograph system, GP)을 이용하여 분리막의 야금학적, 물리학적, 열역학적 특성을 분석하였다. 또한, 물질전과정평가를 위해 수행한 특성화와 정규화 결과, 영향범주 별 환경영향은 해양 생태 독성이 94%, 수계 생태 독성 2%, 인간독성 2%의 기여도를 보였다. 아울러, 제조공정 중 전기 사용이 생태계 영향에 큰 영향을 미친다는 것을 알 수 있었다. 물질 전 과정 평가는 Eco-Indicator '99 (EI99)와 CML 2001 방법론을 기반으로 분석하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 추계학술대회 논문집 학회본부 C
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• pp.822-824
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• 1998

The lithium polymer battery with polymer electrolyte is expected as a safe and long cycle life battery. This paper reports primarily the recent development results of a solid polymer electrolyte, which is a key point of the secondary battery system. The new type of polymer electrolyte was prepared under a dry Ar atmosphere by dissolving $LiCIO_4$ in a matrix of EC, PC and then dispersing polyacrylonitrile(PAN). Also adding some inorganic filler $Al_2O_3$. The dispersed solution heated at $120^{\circ}C$. The polymer electrolyte were characterized by EIS(Electrochemical Impedance Spectroscopy), TGA(Thermo Gravimetric analysis), DMA(Dynamic Mechanical Analyzer), DSC (Differential Scanning Calorimetry). The lithium ion yield is 0.29 when PAN-$Al_2O_3$ which was applied DC 5mV. The ionic conductivity of PAN, PAN-$Al_2O_3$ polymer electrolytes were showed $1.0{\times}10^{-4}S/cm$, $8.4{\times}10^{-4}S/cm$ at room temperature. When inorganic filler was added in the polymer electrolyte, ionic conductivity and lithium yield more larger than without inorganic filler.

• Composites Research
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• 제36권5호
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• pp.315-320
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• 2023

오토클레이브를 사용하는 열경화성 탄소 섬유 복합재 성형 공정에서는 설정한 온도 사이클에 따라 내부 온도가 변화한다. 이 온도 변화에 따라 복합재 수지가 경화되며 성형이 진행된다. 이러한 과정에서 수지의 화학 반응으로 열이 발생하며, 이로 인해 오토클레이브 내부 온도와 복합재의 온도가 다를 수 있는 상황이 나타난다. 이전 연구에서는 복합재와 오토클레이브의 온도를 동일하게 가정하고, 성형 후에 발생하는 잔류 응력과 열 변형을 예측하였다. 그러나 잔류 응력과 열 변형은 복합재 온도와 경화도에 따라 영향을 받는 요소이기 때문에, 본 연구는 수지의 화학 반응열을 고려하여 정확한 온도와 경화도 변화를 계산하는 열화학 모델 해석 기법을 검증하였다. 또한, 이 모델이 다른 두께에서도 이와 같은 경향성을 나타내는지 확인하기 위해 두께별 케이스 연구를 하였다.

• Journal of Welding and Joining
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• 제26권3호
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• pp.61-66
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• 2008

As ships become to be larger than ever, the thicker plate and the higher tensile steel plate are used in naval shipyard. Though special chemical composition is needed for high-tensile steels, recent high-tensile steels are made by the TMCP(Thermo-Mechanical control process) skill. The increase of yield stress and tensile stress of TMCP steels is induced from bainite phase which is transformed from austenite, but that increased yield stress can be vanished by another additional thermal cycle like welding and heating. As thermal deformations are deeply related by yield stress of material, the study for prediction of plate deformation by heating should reflect principle of TMCP steels. This study developed an algorithm which can calculate inherent strain. In this algorithm, not only the mechanical principles of thermal deformations, but also the predicting of the portion of initial bainite is considered when calculating inherent strain. The simulations of plate deformation by these values showed good agreements with experimental results of normalizing steels and TMCP steels in welding and heating. Finally we made an inherent strain database of steels used in Class rule.

• 콘크리트학회논문집
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• 제17권5호
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• pp.857-868
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• 2005

This paper deals with the accumulated damage in concrete structures due to the cyclic freeze-thaw as an environmental load. The cyclic ice body nucleation and growth processes in porous systems are affected by the thermo-physical and mass transport properties, and gradients of temperature and chemical potentials. Furthermore, the diffusivity of deicing chemicals shows significantly higher value under cyclic freeze-thaw conditions. Consequently, the disintegration of concrete structures is aggravated at marine environments, higher altitudes, and northern areas. However, the properties of cyclic freeze-thaw with crack growth and diffusion of chloride ion effects are hard to be identified in tests, and there has been no analytic model for the combined degradations. The main objective is to determine the driving force and evaluate the reduced strength and stiffness by freeze-thaw. For the development of computational model of those coupled deterioration, micro-pore structure characterization, pore pressure based on the thermodynamic equilibrium, time and temperature dependent super-cooling with or without deicing salts, nonlinear-fracture constitutive relation for the evaluation of internal damage, and the effect of entrained air pores (EA) has been modeled numerically. As a result, the amount of ice volume with temperature dependent surface tensions, freezing pressure and resulting deformations, and cycle and temperature dependent pore volume has been calculated and compared with available test results. The developed computational program can be combined with DuCOM, which can calculate the early aged strength, heat of hydration, micro-pore volume, shrinkage, transportation of free water in concrete. Therefore, the developed model can be applied to evaluate those various practical degradation cases as well.

• International Journal of Naval Architecture and Ocean Engineering
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• 제1권2호
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• pp.95-100
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• 2009

As ships become larger, thicker and higher tensile steel plate are used in shipyard. Though special chemical compositions are required for high-tensile steels, recently they are made by the TMCP (Thermo-Mechanical control process) methodology. The increased Yield / Tensile strength of TMCP steels compared to the normalized steel of same composition are induced by suppressing the formation of Ferrite and Pearlite in favor of strong and tough Bainite while being transformed from Austenite. But this Bainite phase could be vanished by another additional thermal cycle like welding and heating. As thermal deformations are deeply related by yield stress of material, the study for prediction of plate deformation by heating should niflect the principle of TMCP steels. The present study is related to the development of an algorithm which could calculate inherent strain. In this algorithm, not only the mechanical principles of thermal deformations, but also the initial portion of Bainite is considered when calculating inherent strain. Distortion analysis results by these values showed good agreements with experimental results for normalized steels and TMCP steels during welding and heating. This algorithm has also been used to create an inherent strain database of steels in Class rule.

• 한국자동차공학회논문집
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• 제20권1호
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• pp.95-105
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• 2012

The selective catalytic reduction (SCR) system is a highly-effective aftertreatment device for NOx reduction of diesel engines. Generally, the ammonia ($NH_3$) was generated from reaction mechanism of SCR in the SCR system using the liquid urea as the reluctant. Therefore, the precise urea dosing control is a very important key for NOx and $NH_3$ slip reduction in the SCR system. This paper investigated NOx and $NH_3$ emission characteristics of urea-SCR dosing system based on model-based control algorithm in order to reduce NOx. In the map-based control algorithm, target amount of urea solution was determined by mass flow rate of exhaust gas obtained from engine rpm, torque and $O_2$ for feed-back control NOx concentration should be measured by NOx sensor. Moreover, this algorithm can not estimate $NH_3$ absorbed on the catalyst. Hence, the urea injection can be too rich or too lean. In this study, the model-based control algorithm was developed and evaluated on the numerical model describing physical and chemical phenomena in SCR system. One channel thermo-fluid model coupled with finely tuned chemical reaction model was applied to this control algorithm. The vehicle test was carried out by using map-based and model-based control algorithms in the NEDC mode in order to evaluate the performance of the model based control algorithm.