A high-pressure in-situ permeation measuring system was developed to evaluate the hydrogen permeation properties of polymer sealing materials in hydrogen environments up to 100 MPa. This system employs the manometric method, utilizing a compact and portable manometer to measure the permeated hydrogen over time, following high-pressure hydrogen injection. By utilizing a self-developed permeation-diffusion analysis program, this system enables precise evaluation of permeation properties, including permeability, diffusivity and solubility. To apply the developed system to high-pressure hydrogen permeation tests, the hydrogen permeation properties of ethylene propylene diene monomer (EPDM) materials containing silica fillers, specifically designed for gas seal in high-pressure hydrogen environments, were evaluated. The permeation measurements were conducted under pressure conditions ranging from 5 MPa to 90 MPa. The results showed that as pressure increased, hydrogen permeability and diffusivity decreased, while solubility remained constant regardless of pressure. Finally, the reliability of this system was confirmed through uncertainty analysis of the permeation measurements, with all results falling within an uncertainty of 11.2 %.

Ti-6Al-4V alloy is widely utilized in aerospace and medical sectors due to its high specific strength, corrosion resistance, and biocompatibility. However, its low machinability makes it difficult to manufacture complex-shaped products. Advancements in additive manufacturing have focused on producing high-performance, complex components using the laser powder bed fusion (LPBF) process, which is a specialized technique for customized geometries. The LPBF process exposes materials to extreme thermal conditions and rapid cooling rates, leading to residual stresses within the parts. These stresses are intensified by variations in the thermal history across regions of the component. These variations result in differences in microstructure and mechanical properties, causing distortion. Although support structure design has been researched to minimize residual stress, few studies have conducted quantitative analyses of stress variations due to different support designs. This study investigated changes in the residual stress and mechanical properties of Ti-6Al-4V alloy fabricated using LPBF, focusing on support structure design.

Gas sensors play a crucial role in monitoring harmful gas concentrations and air quality in real-time, ensuring safety and protecting health in both environmental and industrial settings. Additionally, they are essential in various applications for energy efficiency and environmental protection. As the demand for hydrogen refueling stations and hydrogen fuel cell vehicles increases with the growth of the hydrogen economy, accurate gas concentration measurement technology is increasingly necessary given hydrogen's wide explosion range. To ensure safety and efficiency, gas sensors must accurately detect a wide range of gas concentrations in real-world environments. This study presents two types of gas sensors with high sensitivity, stability, low cost, fast response time, and compact design. These sensors, based on volume and pressure analysis principles, can measure gas filling amounts, solubility, diffusivity, and the leakage of hydrogen, helium, nitrogen, and argon gases in high-density polyethylene charged under high-pressure conditions. Performance evaluation shows that the two sensors have a stability of 0.2 %, a resolution of 0.12 wt･ppm, and can measure gas concentrations ranging from 0.1 wt･ppm to 1400 wt･ ppm within one second. Moreover, the sensitivity, resolution, and measurement range of the sensors are adjustable. Measurements obtained from these sensors of gas filling amounts and the diffusivity of four gases showed consistent results within uncertainty limits. This system, capable of real-time gas detection and characterization, is applicable to hydrogen infrastructure facilities and is expected to contribute to the establishment of a safe hydrogen society in the future.

길이가 긴 터널 내부에서 TNT와 같은 화약의 폭발을 해석할 때, 재연소 현상을 고려하는 것이 매우 중요하다. 재연소 현상을 해석 에 반영하기 위해서는 재연소 에너지와 지속 시간을 적절히 적용해야 한다. 본 연구에서는 터널과 유사한 구조인 충격파관 실험을 통 해 해석 조건을 검증한 뒤, 이를 바탕으로 터널 입구로부터 내부 폭발 위치 변화에 따른 재연소 지속 시간의 경향을 분석하였다. 또한, 이 결과를 폭발 해석에 적용하여 터널 내부 폭압과 충격량의 변화를 분석하였다. 해석은 입구 면적이 0.785m2인 정사각형 단면의 터 널을 모델링하여 수행되었다. 분석 결과, 터널 내부 폭발 위치가 입구에서 깊어질수록 재연소 지속 시간은 일정하게 증가하며 특정 지 점에서 수렴하는 경향을 보였다. 또한, 재연소 지속 시간 증가를 반영한 폭발 해석 결과, 터널 내부 최대 폭압은 폭발 위치가 내부로 이 동함에 따라 증가하다가 특정 폭발 위치 이후로는 더 이상 증가하지 않았다.

Sanghuang mushroom is highly valued for its medicinal potential, including anticancer, anti-inflammatory, and antioxidant activities, and has recently gained significant economic and pharmacological importance. Despite considerable taxonomic revisions within the genus Sanghuangporus, confusion persists in Korea due to the continued use of outdated names such as Phellinus linteus, P. baumii, and Inonotus baumii, as well as inconsistencies in common names. This study aimed to clarify the species diversity of Sanghuangporus in Korea through integrative approaches combining phylogenetic, morphological, and ecological analyses. Using four genetic markers (ITS, nLSU, RPB2, and TEF1), we analyzed 11 dried specimens preserved at the Seoul National University Fungus Collection and 74 fungal strains maintained by the Korean Agricultural Culture Collection. As a result, we identified eight Sanghuangporus species in Korea: S. baumii, S. mongolicus, S. quercicola, S. sanghuang, S. subbaumii, S. vaninii, S. weigelae, and a novel candidate species, Sanghuangporus sp. 1. Among these, S. mongolicus and S. quercicola were newly recorded species for Korea. By providing diagnostic traits and ITS barcode sequences, this study offers a reliable taxonomic framework for the accurate identification of Sanghuangporus species. It also supports future taxonomic studies, cultivar development, and applied research in pharmaceutical and functional bioactive materials.

The Indian Ocean is the second-largest tuna fishing ground in the world, accounting for approximately 1.2 million tonnes (23%) of the estimated 5.2 million tonnes of global commercial tuna catch in 2023. This study examined the relationship between tuna catches, specifically skipjack, bigeye, and yellowfin tunas, and prey biomass (Nautical Area Scattering Coefficient, NASC) estimated from acoustic surveys conducted in the southwestern Indian Ocean from 20 April to 15 May 2019. Environmental variables were derived from the Copernicus Ocean Model, and tuna length data from the IOTC. The estimated total tuna catch in the study area was approximately 166,400 tonnes, with the northwestern region showing the highest catches and NASC values. Tuna catches increased with NASC; however, the relationship was non-linear. While skipjack showed no significant correlation with NASC, bigeye and yellowfin tunas exhibited weak but significant positive correlations. Environmental analysis revealed that the northern waters had high surface temperatures, low salinity, and low oxygen levels, with mid and deep layers characterized by low temperature, salinity, oxygen, and chlorophyll. These findings offer a foundation for understanding tuna distribution in relation to prey and environmental conditions, highlighting the need for future species- and fishery-specific studies to support sustainable tuna resource management.

This study aimed to enhance the operational efficiency and safety of offshore eel trap fisheries by developing six types of automated fishing equipment: a bait crusher, bait cutter, main line arranging device, trap cleaning device, eel sorting device, and fish pump system. Sea trials demonstrated that the bait crusher and bait cutter significantly reduced manual labor and processing time while maintaining bait quality. The main line arranging device improved productivity and safety by automating the sorting of looped cords. The trap cleaning device effectively removed fouling organisms using high-pressure water and rotating brushes. The eel sorting device enabled automatic size-based selection, improving resource management and operational efficiency. The fish pump system transferred eels rapidly with minimal physical damage, reducing unloading time by over 80% and decreasing labor requirements. A satisfaction survey of fishery participants confirmed that all developed devices were highly effective in reducing workload, enhancing safety, and improving operational performance. The automated equipment developed in this study is expected to contribute to the sustainable management of offshore eel trap fisheries and to offer potential applicability to other coastal and offshore fisheries.

This study examined the offshore eel trap fishing process using one year of fishing logs and fishermen’s insights to identify key operational challenges and propose equipment improvement for greater efficiency and safety. Conger eel catches varied significantly by season, depth, and temperature, peaking in winter at 85–90 m and 23°C. The western waters of Jeju Island were identified as a major fishing ground, with the highest catch recorded in November and the lowest in July, reflecting seasonal trends. Each fishing operation deployed about 10,000 traps, with an average loss of 38 traps, posing economic concerns. The process involved intensive manual labor in bait preparation, trap retrieval, catch separation, line loading, and unloading, leading to high physical demands and safety risks. To address these issues, the study proposed automation through the development of a line loading device, trap cleaning device, bait processing machine, and automatic catch separator. These innovations could reduce the labor force required by one to two workers per process, alleviate workloads, and enhance resource management. By integrating quantitative logbook analysis with field-based knowledge, this study offers practical value. Further research is recommended on automation development, cost-effectiveness, and field validation to support safer and more sustainable eel trap fisheries.

본 연구는 직장인의 정신 건강 문제를 해결하기 위한 새로운 접근법으로 뮤지컬 워크숍 참여가 우울감과 스트레스 감소에 미치는 영향을 실증적으로 분석하고자 했다. 현대 직장인들은 과도한 업무, 복잡한 대인관계, 고용 불안정 등으로 인해 높은 수준의 스트레스와 우울감을 경험하고 있 으며, 이는 개인의 삶의 질 저하와 조직 생산성 감소로 이어질 수 있다. 이에 따라 예술 활동이 정서적 안정과 스트레스 감소에 긍정적인 영향을 미친다는 점에 주목하여, 터치아트컴퍼니에서 진행된 일반인 뮤지컬 워크숍 참여자 20명을 대상으로 설문조사를 실시하였다. 연구는 단일 집단 회고적 사전-사후 설문조사를 통해 뮤지컬 워크숍 참여 전후의 우울감과 스트레스 수준 변화를 측정하였다. 분석 결과, 워크숍 참여 후 참가자들의 우울감과 스트레스가 유의미하게 감소한 것으 로 나타났으며, 이는 통계적으로도 유의미한 효과를 보여주었다. 또한, 개방형 설문 응답을 통해 참가자들이 자신감 향상, 일상의 활력 증가, 새로운 사회적 관계 형성, 성취감 및 긍정적 감정 증가 등을 경험했음을 확인하였다. 본 연구는 뮤지컬 워크숍이 직장인의 정신 건강 증진을 위한 효과적인 예술 활동임을 입증하며, 지역 사회 문화 예술 프로그램 활성화와 직장인들의 삶의 질 향상에 기여할 가능성을 제시한다. 그러나 표본 크기의 제한과 통제 집단 부재 등의 한계점을 고 려하여 향후 연구에서는 더 큰 규모의 표본과 장기적 효과 분석을 포함한 심층적인 연구가 필요하 다.

A technology was developed to measure the hydrogen uptake and diffusivity of polymer materials used in high-pressure hydrogen tanks and pipelines at hydrogen refueling stations. This technology involves charging hydrogen into polymer under a maximum pressure of 90 MPa, followed by depressurization. The polymer material is then placed in a cylinder partially submerged in water, and hydrogen is released from the material. The increase in volume of the released hydrogen causes a decrease in the water level in the cylinder. To track this in real-time, an image analysis algorithm based on the brightness of a crescent-shaped water level image is used to accurately measure the water level and change in hydrogen amount at the same time. This data is then used in a self-developed diffusivity analysis program to evaluate hydrogen uptake and diffusivity. Using this technology, the hydrogen uptake and diffusivity of sulfur-crosslinked nitrile butadiene rubber (NBR) composites containing carbon black and silica fillers were measured from 2 to 90 MPa. Additionally, the relationship between the physical stability of the NBR composites and their hydrogen uptake and diffusivity was investigated. To validate the effectiveness of the technology, an uncertainty analysis of the measurements was conducted, with all results showing an uncertainty within 8 %.

Microalgae are efficient fatty acid producers owing to their high photosynthetic activities. They can act as sources of biofuel, feed, and various bioactive compounds. This study aimed to determine optimal culture conditions, including culture medium, temperature, and light intensity, to enhance the biomass and fatty acid content of the indigenous freshwater microalga, Tetradesmus obliquus. Evaluation using a high-throughput photobioreactor revealed that the optimal culture temperature and light intensity were 25°C and 300 μmol m-2 s-1, respectively. Additionally, we optimized components (N, P, and Mg) of the BG-11 medium to enhance the microalgal biomass. Modified BG-11 medium increased the T. obliquus biomass by 37% compared to the standard BG-11 medium. Subsequently, the culture medium was replaced with N- and P-depleted media to determine the abiotic stress factor that could increase the cellular fatty acid content. Notably, fatty acid content was significantly increased from 8.5% up to 14.6% on day 7 of culture in N-deficient (N-P+ and N-P-) media. Sequential optimization effectively increased the biomass by 83% and fatty acid content by >76% in T. obliquus. Our optimization method can be used to enhance the biomass and fatty acid contents of various other microalgae.