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.

The purpose of this study is to fabricate a multi-stage, variable-section and high-speed of the cutting device for recycling carbon fiber from waste hydrogen storage tanks. In this study, a high precision cutting device is fabricated utilizes (i.e., multi-stage, variable-section, high-speed cutting function and a diamond wire tool) to cut various waste hydrogen storage tank carbon fibers into scrap in a short period of time. The fabricated items include the development of diamond wire tools and wheels, cutting feed systems, structural frames, cooling system applications, and hydrogen tank fixing systems. The rotational speed of multi-stage wheel is in range of 0~600 rpm, and feed speed of diamond wire cutting tools is in range of 10–80 mm/min. The results showed that a new precision cutting device is able to cut the waste hydrogen storage tanks more than 400 pieces of performance indicator scrap (200×200 mm) within 8 hours of the cutting time. This confirmed that a new fabricated cutting device is a high speed cutting machine that is feasible for application in waste hydrogen storage tanks recycling in stead of conventional cutting device.

This study was carried out in a cold storage chamber with a floor space of roughly 3.3 square meters (1 pyeong). The findings revealed that the hybrid cooling system consumed a comparable amount of electricity to that of the conventional vapor compression system. This similarity in power usage can be attributed to the hybrid system’s operational strategy: thermoelectric modules were selectively activated during periods of frost accumulation, effectively minimizing the energy typically used for electric defrosting in vapor compression units. To advance the commercialization of this hybrid system in cold storage applications, several technical improvements must be considered in addition to cost optimization. First, the design should address the bulky nature of the heat exchanger setup. At present, the vapor compression and thermoelectric modules are housed in separate outdoor units; a more efficient approach would involve integrating them into a single, space-saving unit. Second, incorporating a water mist spray mechanism for the outdoor heat exchanger coil could enhance heat dissipation. This method, which leverages latent heat exchange, has demonstrated strong performance in other applications and merits further investigation for use in the proposed system.

본 연구는 염소 도축공정 확립을 위해, 도축 과정 중 탕박(scalding) 및 박피(skinning)가 재래흑염소 등심의 저장 중 물리화학적 특성에 미치는 영향을 비교 분석하고자 수행되었다. 동일한 사양 조건에서 사육된 재래흑염소 6 두를 각각 탕박 및 박피 과정에 따라 도축한 후, 등심근을 채취하여 저장 기간 동안 이화학적 특성 변화를 관찰하여 재래흑염소에 적합한 도축 방법을 선택하고자 하였다. 그 결과, 탕박처리는 전반적으로 연도를 개선하는 데 효과적인 것으로 나타났으며, 박피 처리는 저장 중 보수력 유지에 우수하고, 색도의 선명도(a*, chroma)와 지질산화에 더 안정적인 특성을 보였다. 탕박은 소비자의 기호도 측면에서 유리한 부드러운 조직감을 제공할 수 있지만, 박피는 특히 위생적 안전성과 품질 균일성 확보 측면에서 더 바람직한 도축 방법으로 판단된다.

Sperm storage is a crucial reproductive adaptation that ensures fertilization success by maintaining viable sperm until ovulation. Birds and mammals have evolved anatomically distinct yet functionally analogous structures, sperm storage tubules (SSTs) in the avian female reproductive tract and the epididymis in the mammalian male reproductive tract, that represent a striking example of convergent evolution. These systems prolong sperm lifespan and regulate fertilization timing through shared physiological strategies. While each system has been studied independently, a direct comparison between SSTs and the epididymis has not been thoroughly explored. This review proposes that, although structurally distinct, SSTs and the epididymis exhibit shared physiological strategies such as metabolic suppression, pH and ion regulation, oxidative stress control, and hormonally mediated sperm release. By highlighting these parallels, we present a novel perspective on sperm storage as a case of evolutionary convergence in reproductive physiology. Understanding these shared mechanisms provides new insights into sperm viability regulation and offers practical implications for assisted reproductive technologies (ARTs), such as improved cryopreservation strategies and biomimetic sperm storage platforms designed to mimic SST or epididymal conditions.

This study numerically investigated thermal-structural characteristics of a liquefied hydrogen (LH) storage cylinder with varying inner pressures and surrounding temperatures. A thermal-structure coupled analysis approach was used to predict the thermal-structural characteristics of the LH storage cylinder. For the simulation, the shape of the LH storage cylinder was simplified using SUS 316L and Carbon Fiber Reinforced Plastic (CFRP) materials. As a result, the inner pressure was a crucial factor determining the structural property (i.e., stress and deformation) of the LH storage cylinder. The high pressure led to increased stress and deformation. Additionally, the surrounding temperature affected the stress and deformation of the LH storage cylinder. For example, at a high surrounding temperature, the temperature gradient along the cylinder increased, thereby causing the occurrence of thermal stress. However, this temperature effect on the stress was negligible compared to the effect of inner pressure. The findings of this study will provide meaningful data for improving the structural safety of LH storage systems.

Developing advanced anode materials is one of the effective strategies to enhance the electrochemical performance of sodiumion batteries (SIBs). Herein, inspired by the biological central nervous system structure, we report a facile and efficient strategy to fabricate the three-dimensional hierarchical neural network-like carbon architectures, where the glucose-derived hard carbon (HC) nanospheres are in situ assembled and embedded in carbon nanotube (CNT) network nanostructure (HC/CNT hybrid networks). The HC nanospheres with large carbon interlayer spacing help to decrease the diffusion length of sodium ions and the interconnected CNT networks enable the rapid electron transfer during charge/discharge process. Benefiting from these structure merits, the as-made HC/CNT hybrid networks can deliver a superior rate capacity of 162 mA h g− 1 at the current density of 5 A g− 1. Additionally, it exhibits excellent cycling performance with a capacity retention rate of 86.3% after 140 cycles. This work offers a promising candidate anode material for SIBs and a new prospect towards carbon-based composites design, simultaneously.

Industrialization and increasing consumerism have driven up energy demand and fossil fuel consumption, significantly contributing to global climate change and environmental pollution. While renewable energy sources are sustainable, their intermittent nature necessitates the development of efficient energy storage devices to ensure uninterrupted power supply and optimal energy utilization. Electrochemical energy storage devices are promising for sustainable energy. Traditionally, carbon electrode materials for these devices come from non-renewable sources. However, using biomass and biomass–coal blends can help substitute fossil fuels, reducing environmental impact. Recent advancements in carbon materials have achieved specific surface areas of over 2500 m2/ g, resulting in supercapacitor capacitances of 250–350 F/g and cycling stability exceeding 10,000 cycles with < 5% capacity loss. In lithium-ion batteries, biomass-based anodes deliver 400–600 mA h/g, outperforming graphite. Doped carbon materials enhance charge-transfer efficiency by 20–30%, while CO₂ emissions from production are reduced by 40–60%. With 50–70% lower costs than fossil-based alternatives, biomass-derived carbons present a viable pathway for scalable, eco-friendly energy storage solutions, accelerating the transition toward sustainable energy systems. Overall, this work highlights the influence of carbon materials on the electrochemical properties and hydrogen storage capacity of biomass-based carbon materials. This also underscores their potential application in energy storage.

This study analyzed the methods and characteristics of hydrogen production, storage, transportation, charging, and use of hydrogen presented as an energy supply and demand system for hydrogen. Hydrogen produced by reforming hydrogen, which exists in the form of compounds, is essential to use metal materials exposed to the hydrogen atmosphere in storage and transportation. The mechanism of hydrogen embrittlement and damage cases, which are phenomena in which hydrogen atoms penetrate into the crystal lattice of metal and cause crack failure, were investigated. In addition, it is intended to present a research direction related to the evaluation of physical properties such as thermal conductivity, thermal expansion coefficient, and heat capacity, which are the criteria for selecting materials for hydrogen in a cryogenic environment.

This experiment was conducted in a 1-pyeong cold room. Looking at the experimental results, it can be seen that the power consumption is twice as high when the thermoelectric module cooler is used compared to when the steam compression type cooler is operated. As is commonly known, steam compression coolers have a COP of about 3.0 in commercial coolers such as air conditioning systems and refrigerators, and the COP of coolers using thermoelectric modules is about 1.0, showing a performance difference of about 3 times. The reason for this difference is that the heat conduction fin material and shape were optimized, and the defrosting power consumption was relatively small in the thermoelectric method. The performance of thermoelectric devices shows that although there are still many improvements to be made over existing methods, they can exhibit sufficiently different advantages depending on the system.

This study analyzed the changes in sodium content across different types of kimchi over various storage periods, distinguishing between solids and seasoning (liquid), to better estimate actual sodium intake and improve the food composition databases. Six types (baechu-kimchi, oi-sobagi, buchu-kimchi, baek-kimchi, dongchimi, and nabak-kimchi) were analyzed using ICP-AES. The results were compared with salinometer readings, food composition databases, and nutrition labels from commercial products. Statistical analyses included the Mann-Whitney U test and the Kruskal-Wallis test (=0.05). The findings showed that the seasoning had significantly higher sodium content than the solids and, except for baechu-kimchi and nabak-kimchi, accounted for more than 50% of the total sodium content. Sodium content varied across kimchi types and changed over storage time. Additionally, sodium content measured by ICP-AES significantly differed from those in the food composition databases and commercial nutrition labels, which often over or under-estimated values. Moreover, sodium content in commercial kimchi products exhibited up to a 581-fold difference between the minimum and maximum values. These results suggest that current databases and labeling systems, which do not distinguish between solids and seasoning, may misrepresent the actual sodium intake. Further research and regulatory measures are needed to improve sodium estimation and consumer guidance.

This study investigates the factors influencing the seed longevity of Quercus myrsinifolia, a species with recalcitrant seeds highly sensitive to desiccation and freezing. The effects of moisture content, seed collection date, and storage methods on seed viability were analyzed using exponential decay modeling. Interactions between these factors were also explored to refine conservation strategies. Seeds with moisture content above 40% demonstrated a predicted seed longevity of 2.19 years, whereas those with moisture content below 30% had seed longevity of less than 1 year. Late-season seeds collected in November and December exhibited superior germination percentages and longer predicted seed longevity (1.32 years) compared to early-season seeds collected in September and October (<1 year). In seed weight, large seeds (2.0 g) showed longer predicted seed longevity about 1.5 times greater than that of small seeds (<1.2g). Storage methods significantly affected seed longevity, with refrigerator (4°C) with silica gel maintaining viability for 2–3 years, while seeds stored at room temperature (25°C) exhibited a seed longevity of less than 1 year. Silica gel was found to prevent seed deterioration due to over-desiccation, emphasizing the importance of balanced moisture regulation. Q. myrsinifolia seeds exhibited 𝑏 values ranging from 0.30 to 2.04, demonstrating a close relationship between decay constant, moisture content, storage conditions, and seed longevity. These findings provide critical insights into optimizing seed storage and propagation strategies for Q. myrsinifolia, contributing to its conservation and ecological restoration efforts.

Carbon neutrality by 2050 was declared and are focusing on developing innovative energy technologies aimed at reducing greenhouse gas emissions. Active investment and research are underway in the full-cycle development of hydrogen energy technologies, including hydrogen production, storage, transportation, and utilization, which is gaining attention as a promising future eco-friendly energy source. The storage density of liquid hydrogen is 70.79kg/m3, which is higher than the 41kg/m3 of compressed hydrogen at 700bar, making it more suitable for large-scale storage. To store hydrogen at 20K, insulation technologies such as vacuum insulation, powder insulation, or multi-layer insulation (MLI) are typically required. Consequently, there is active research being conducted on the design of insulation systems and materials. However, research on the design for improving the structural integrity of the supports between the inner and outer tanks remains insufficient. n this study, topology optimization was performed for the support design of a liquid hydrogen storage tank using commercial finite element analysis (FEA) software. The structural safety was validated through structural analysis of a simplified self-designed model.