The use of hydrogen as an energy carrier has gained widespread adoption in warehouses and industrial environments. This increasing adoption necessitates the need for stringent safety evaluations specifically for enclosed fueling systems where the potential of accidental discharges may result in explosions or jet fires. This study demonstrates a quantitative risk assessment of an indoor hydrogen dispenser positioned in a warehouse facility using the Hydrogen Risk Assessment Models (HyRAM+) version 6.1 software developed by Sandia National Laboratories. A representative 120 m x 120 m x 10.62 m housing a 70 MPa gaseous hydrogen dispenser used in the refueling of hydrogen-powered vehicles in an enclosed space scenario was modeled Based on realistic industry standard assumptions system geometry conditions of operation and component inventory were defined. HyRAM+ was employed to evaluate deterministic and probabilistic models to determine potential loss of life (PLL), fatal accident rate (FAR), and average individual risk (AIR). The PLL, FAR, and AIR values of 1.05 x 10-4 fatalities per year 0.02 fatalities per 100 million working hours and 5.99 x 10-7, respectively indicate negligible individual risk under the modeled conditions. Additionally flame and leak analysis revealed smaller sizes of leaks being likely to result in no ignition and safe shutdown with larger leak size resulting in the probability of explosion or jet fire. Furthermore radiative heat flux analysis of a 6.223 mm leak also revealed the occurrence of peak heat flux along the jet axis with a decrease in distance demonstrating that thermal exposure is highly directional. These findings demonstrate that the assessed indoor hydrogen dispenser operates within acceptable safety limits and highlight the effectiveness of HyRAM+ as a tool for hydrogen safety designs.

The renewable energy has, currently, been used because of its eco-friendly energy such as no emission gas and less environmental pollution. Fuel cell electric vehicle (FCEV) using polymer electrolyte membrane fuel cell (PEMFC) uses the hydrogen as fuel to obtain the power by electrochemical reaction. The objective of this study is to investigate the flow characteristics of the hydrogen according to entrainment ratio for ejector of FCEV through comparison analysis with the air. As the results, the flow of hydrogen in ejector corresponds to turbulence with Reynold number 18,093. The pressure difference of the hydrogen between primary flow and secondary flow in ejector was about 16 times compared with that of the air. The mean velocity of the hydrogen in ejector outlet was faster about 15 times than the air.

Performance of the hydrogen fuel cell system in a compact special vehicle is mainly influenced by the thermal characteristics of heat release through air flow with electrochemical mechanisms. In this study, numerical analysis has been carried out to investigate air flow and heat transfer characteristics near the fuel cell system for various operating conditions. The cooling characteristics around the radiator system depend on air flow generated by vehicle movement, and the effects of vehicle-induced air flow on the velocity and temperature distributions within the heat release system were examined. These results showed that there are quite complicated air flow around the radiator and fan near the fuel cell system in the vehicle cargo area, and its efficient flow field resulted in cooling performance improvement with driving speed. Hence overall heat release characteristics of the hydrogen fuel cell system are strongly associated with various air flow behavior formed around the compact special vehicle including cargo area.

The effect of metal codoping on hydrogen storage has been meticulously studied in small cubic C8 nanocluster within the framework of density functional theory (DFT). Initially, a C8 nanocluster was doped with two Li atoms [ C8(Li)2], achieving a hydrogen uptake of 15.5 wt% with an adsorption energy of 0.16 eV. Although this configuration demonstrates a high hydrogen storage capacity, its thermodynamic stability under ambient conditions is limited due to weak binding interactions between Li and H2 molecules. By introducing metal atoms that have stronger binding with the C8 framework, it is expected to enhance the overall structural stability. For that, we have chosen Na, K, Be, Mg, Ca, Sc, Ti, V, and Cr metal atoms along with Li to investigate the influence of codoping on hydrogen storage characteristics. The Ti- and V-codoped structures exhibited significant distortion of the C8 nanocluster during optimization primarily due to strong charge transfer, steric repulsion arising from the larger atomic radii of Ti and V, and partial bond breaking within the nanocluster framework and were, therefore, excluded from further calculations. The resulting codoped structures—C8LiNa, C8LiK, C8LiBe, C8LiMg, C8LiCa, C8LiSc, and C8LiCr— yielded hydrogen uptake of 16.1 wt%, 14.6 wt%, 11.2 wt%, 13.7 wt%, 12.4 wt%, 9.8 wt%, and 11.5 wt%, respectively, all surpassing the U.S. Department of Energy 2025 target of 5.5 wt%. Among these, the LiCr codoped C8 nanocluster exhibited significantly improved adsorption energies of 0.31 eV, which is within the ideal range of 0.2–0.6 eV for faster adsorption–desorption kinetics. Furthermore, Gibbs free energy corrections to H2 adsorption energy at various temperatures and pressures revealed superior thermodynamic stability of the C8LiCr structure, suggesting its promising potential for practical hydrogen storage applications. These results highlight the significant impact of metal codoping as a powerful strategy for enhancing hydrogen uptake, stability, and overall H2 storage performance in nanostructured materials.

본 연구는 선박용 내연 기관에 적용되는 연료 분사 노즐을 대상으로, 수소 연료 운전 조건에서의 구조적 거동을 규명하기 위해 정적 열-구조 연성(static thermo-structural coupled) 유한요소 해석(FEA)을 수행하였다. 해석은 상용 프로그램 ANSYS Mechanical 2025 R1을 사 용하였으며, 주요 경계 조건으로 연료 공급 온도 -60°C~120°C, 연료 공급 압력 60 bar 및 연료 분사 압력 60 bar를 적용하였다. 또한 노즐 니들의 개폐(open/close) 상태를 각각 모델링하여 니들의 개폐에 따른 구조적 응답 변화를 비교하였다. 해석 결과, 노즐의 최대 등가 응력 (maximum equivalent stress)은 니들 폐쇄 상태에서 니들 개방 상태에 비해 약 1.6배 높게 나타났으며, 최대 등가 응력은 모든 조건에서 유로 벽면에 집중되었다. 이러한 결과는 수소 연료 적용 시 노즐의 잠재적 취약 부를 사전에 예측할 수 있음을 시사하며, 내수소성 확보를 위 한 재료 선정 및 구조 보강 설계의 기초 자료로 활용될 수 있다. 제안된 해석 접근법은 향후 수소 내연기관용 노즐의 내구성 향상, 형상 최적화 및 신뢰성 평가를 위한 기반 연구로서 의의가 있다.

Hydrogen embrittlement (HE) remains one of the most critical challenges in ensuring the structural integrity of steels for hydrogen energy infrastructures, including storage and transport systems. Despite decades of research, the underlying mechanism of HE is still not fully understood due to the complexity of hydrogen-microstructure interactions across multiple length scales. Cryogenic Atom Probe Tomography (Cryo-APT) has recently emerged as a unique method of providing near-atomic resolution and compositional sensitivity for hydrogen analysis, thereby enabling direct visualization of hydrogen distribution at defects, interfaces, and precipitates. This review summarizes recent progress in Cryo-APT-based investigations of hydrogen behavior in steels, with a focus on trapping mechanisms, the role of microstructural features, and the synergistic activation of multiple HE mechanisms. Key technical developments, such as cryogenic workflows and isotope tracing, have significantly advanced the reliability of Cryo-APT hydrogen quantification. Case studies on ferritic-martensitic steels, pearlitic steels, and advanced high-strength steels highlight the potential of Cryo-APT to reveal both diffusible and non-diffusible hydrogen trapping. While current limitations include local sampling bias, experimental complexity, and signal interpretation challenges, continuous improvements in methodology and integration with multiscale modeling are expected to establish Cryo-APT as a core approach for elucidating HE mechanisms. This review provides a comprehensive perspective on the current technical state and future directions of Cryo-APT in HE researches.

Thermal barrier coatings (TBCs) for hydrogen-fueled gas turbines withstand higher combustion temperatures and increased steam concentrations compared to conventional natural-gas systems. These harsh operating conditions significantly accelerate the thermal degradation of widely used YSZ coatings, emphasizing the need for alternative top-coat materials with improved phase stability and reduced thermal conductivity. In this study, rare-earth zirconate ceramics, Gd2Zr2O7 (GdZO), Tm2Zr2O7 (TmZO), and a mixed composition (Gd0.5Tm0.5)2Zr2O7 (Gd/TmZO), were synthesized and investigated as potential next-generation TBC candidates. Each material was comparatively examined with a focus on crystal structure, thermophysical properties, and thermal conductivity. Furthermore, high-temperature steam exposure experiments were performed to simulate hydrogen combustion environments. Microstructural analyses, high-temperature degradation behavior, and phase stability evaluations were carried out to obtain fundamental experimental data. This study provided essential baseline information for the design and development of high-performance TBC materials suitable for the hydrogen-fueled gas turbine systems.

본 연구에서는 α-Al2O3 중공사 지지체 위에 γ-Al2O3, SiO2 산화막 및 Pd 금속막을 각각 증착하여 수소 분리막을 제작하고, 암모니아 열분해 반응 후 생성되는 혼합기체(H2, N2, NH3)에 대한 투과 성능을 비교⋅분석하였다. scanning electron microscope과 atomic force microscope 분석 결과, 산화막 코팅을 통해 표면 조도가 크게 개선되어 Pd 무전해도금 시 결 함 억제에 기여할 수 있음이 확인되었다. 기체투과실험은 450°C, 0.5~2.0 barg 조건에서 수행되었으며, 산화막 기반 분리막은 기공 투과 메커니즘에 의해 최대 수소 순도가 82%에 머무른 반면 금속막 기반 분리막은 용해–확산 기반의 bulk diffusion 메 커니즘을 통해 97% 이상 순도의 수소를 안정적으로 분리하였다. 특히 Pd/α 중공사막은 2 barg에서 15 mL/min 이상의 수소 flux와 1900 이상의 H2/NH3 seperation factor을 기록하며 산화물 기반 분리막보다 월등한 성능을 보였다. 결론적으로 산화물 막은 단독 분리 성능은 제한적이지만 Pd 증착을 위한 전처리 및 중간층으로서 유효함이 확인되었으며, Pd 중공사막은 고온 수소 정제 공정에 가장 적합한 선택지임을 입증하였다.

메탄화 공정은 탄소 포집 및 활용(CCU) 기술의 하나로, 탄소중립 달성을 위한 핵심 기술이다. 본 연구는 메탄화 반응기 배출가스에서 생성가스인 메탄과 미반응 수소를 분리하기 위한 가스 분리 시스템 설계를 위한 사전 연구로, 소형 막 모듈을 이용한 2단 분리막 시스템을 설계⋅제작하고 시험 가스인 질소-수소 혼합가스에 대한 분리 성능을 실험적으로 평가하 였다. 1단 막 모듈에서는 질소-수소 혼합가스에 대한 혼합 가스 선택도를 측정하였으며, 1단 및 2단 막 모듈 모두에서 잔류 측과 투과 측의 목표 가스 회수율 및 순도를 분석하였다. 본 연구에서 수행한 국내 A사 막 모듈의 성능 분석 결과는 향후 메 탄화 반응 가스 분리 시스템 설계 및 최적화 연구의 기초자료로 활용될 수 있다.

Efficient energy conversion technologies require cost-effective and durable catalysts for water oxidation. This study presents SnS2/ C composite synthesized via solvothermal method to enhance electrocatalytic performance in water splitting. Morphological analysis reveals that carbon incorporation disrupts the flower-like SnS2 nanosheets, increasing active site accessibility and improving charge transfer efficiency. Three different electrolytes (KOH, PBS and H2SO4) are systematically employed to evaluate the material’s electrocatalytic activity comprehensively. The electrochemical tests indicate that pure SnS₂ exhibits an overpotential (η) of 410 mV at 10 mA/cm2 for oxygen evolution reaction (OER) in 1 M KOH. Integration of carbon significantly lowers this value to 180 mV with a tafel slope of 103 mV/dec for SSC12 (1:2 SnS₂/C) composite. For hydrogen evolution reaction (HER) in acidic media, SSC12 achieves an η of 275 mV at 500 mA/cm2 with a tafel slope of 121 mV/dec. The catalyst further demonstrates strong durability for OER in 1 M KOH but shows diminished HER activity in 0.5 M H2SO4. This study demonstrates the synergistic role of carbon in enhancing SnS₂ catalytic attributes, emphasizing the potential of these composites for sustainable energy conversion applications.

본 연구는 액체수소 저장 환경에서 사용되는 온도 센서 및 트랜스미터를 대상으로 신뢰성 평가를 수행하고자 FMEA(Failure Modes and Effects Analysis)와 QFD(Quality Function Deployment)를 적용하였다. 고장 심각도, 발생 가능도를 기준으로 주요 고장모드를 도출 하였으며, 사용자 요구사항과 인증기관 기준을 바탕으로 도출된 기술 요구 항목에 따라 QFD 분석을 수행하였다. FMEA 결과, Thermowell 의 풀림이 위험도 7점으로 주요 고장으로 식별되었다. QFD 분석 결과로는 내환경시험 항목으로 습도시험이 중요도 점수 5000점으로 가장 높은 중요도를 나타냈다. 이어서 수명 및 극저온 항목의 중요도도 높게 평가되어, 극저온 수소 환경에서의 센서 구성품 및 보호 구조체의 견고성과 환경 내구성 시험 전략의 중요성이 강조되었다.

본 연구는 수소 저장 용기의 지진 취약도 분석 시 요구되는 막대한 계산 자원 문제를 해결하고자, 기하학적 대칭성을 활용한 1/4 대칭 유한요소 모델(Quarter Model)을 개발하고 그 타당성을 검증하였다. 표준화된 AC 156 인공지진을 이용한 비선형 시간 이력 해석을 통해 Full Model과 응답을 비교한 결과, Quarter Model의 해석 시간을 Full Model의 20%를 가지고 해석을 완료하였으 며, 이에 따른 신뢰성 확보를 위해 최상단 변위를 통해 이를 검증하였을 때 0.13%의 미미한 오차를 보이며 변위 시간 이력 양상 역시 동일한 거동을 보이며 효율성 확보라는 연구 목표를 달성했다. 또한, 고유진동수, 강재와 콘크리트 주요부의 최대 응력에서 모두 높은 수준의 일치도를 보여 정량적 신뢰도를 입증하였다. 이를 통해 제안된 모델은 해석 정확도를 유지하면서 계산 비용을 획기적으로 절감 하는 효율적인 방법론임을 확인하였다. 다만 이는 균질 등방성 재료인 강재에 한정된 대칭 모델이며, 그 외의 재료 사용 시 추가적인 연구를 통한 모델 구축이 필요할 것으로 판단된다.