This paper proposes an Adjustable Circular Steel Connector(ACS) to enable immediate response to construction errors that may occur during the on-site assembly of modular members. To evaluate its flexural performance, one rectangular steel tube beam specimen without ACS and three specimens with ACS(with varying ACS lengths) were fabricated. Experimental results showed no pull-out occurred between Shank A and Shank B, and the application of ACS facilitated stress distribution in the rectangular steel tube. The specimens with ACS exhibited up to 92% of the maximum load capacity of the monolithic specimen, and showed increasingly ductile behavior as the ACS length increased. Due to the cross-sectional difference between Shank A and Shank B within the ACS, yielding was observed in Shank B. Further studies are needed on this part, as well as on the behavior of the ACS under cyclic loading conditions.

본 연구에서는 실험실 규모의 혈액투석 실험 장치를 구성하고 polysulfone (PS) 중공사막과 polyethylene terephthalate (PET) 소재의 모노 및 멀티 스페이서 얀(spacer yarn)을 적용한 5 종류의 소형 혈액투석 모듈을 제작하여 스페이서의 존재가 혈액투석 모듈에 미치는 영향을 확인하였다. 수투과도 측정 결과에서 스페이서가 없는 모듈의 flux가 가장 높은 것으 로 확인되었으나, 이는 스페이서를 적용한 모듈의 막표면적이 감소한 원인으로 분석된다. 반면, 요소(urea) 제거 실험에서는 스페이서 적용 여부와 종류에 따른 성능 차이가 뚜렷하게 나타났으며, 스페이서가 내부 유동 균일화에 기여함으로써 확산 저 항을 감소시키는 효과가 확인되었다. 특히 모노 스페이서를 10 wt% 적용한 모듈은 낮은 막표면적에도 불구하고 혈액투석 실 험 3 h 경과 시점에서 약 67.99%의 요소 제거율을 기록하여, 스페이서를 적용하지 않은 모듈(62.75%) 대비 약 5.24% 높은 요소 제거 효율을 나타냈다.

This study was conducted to improve the stability of small barges used for remote bird monitoring at Capsosiphon fulvescens aquaculture farms. The monitoring accuracy is compromised by rolling and pitching motions induced by waves and wind. To address this problem, a damping system was developed to enhance barge stability. Field experiments were conducted at a farm to evaluate the effectiveness of the developed damping system. The rotational motions of the barge, with and without the damping system, were measured using a six-axis gyroscope sensor. The measurements were conducted at the Capsosiphon fulvescens farm located in Cheokchan-ri and Deokdong-ri, Gogeum-myeon, Wando-gun, Jeollanam-do across two periods: from October 5, 2024 to December 17, 2024 (Damping without) and from February 19, 2025 to April 15, 2025 (Damping with). The collected data were validated against wind speed records from the Korea Meteorological Administration. The results demonstrated that the damping system effectively reduced barge motion. Within a wind speed range of 0.1-9.0 m/s, the system achieved an average reduction of 7.11% in rotational motions. Its maximum performance was recorded at approximately 7.0 m/s wind speed where it achieved a reduction of 23.35%. These findings confirm the system significantly enhances barge stability and improves monitoring reliability.

Current seismic design provisions prohibit the use of a weak panel zone from using special moment frame (SMF) connections due to concerns that large deformations in these zones may lead to brittle connection failures. However, several experimental studies have demonstrated that moment connections with weak panel zones can exhibit adequate ductility and energy dissipation capacity for SMF connections. This study aims to investigate the impact of weak panel zones on the seismic performance of SMFs utilizing welded unreinforced flange-welded web (WUF-W) connections, as outlined in AISC 358-22. The analysis will consider both four-story and twelve-story SMFs. Each frame will be modeled with either strong or weak panel zones. The findings indicate that SMFs with weak panel zones demonstrate greater ductility and collapse strength compared to their counterparts with strong panel zones.

This study compared the physical properties and catch performance of gillnets made from biodegradable PBEAS (butylene succinate-co-adipate/terephthalate-co-ethylene succinate) resin with those of conventional PA (polyamide) gillnets in coastal gillnet fisheries targeting Pampus argenteus. Mechanical tests showed that PBEAS nets showed tensile strength and elongation similar to PA nets. In field trials, the total catch weight of PBEAS nets (596.6 kg, 261 individuals) was slightly higher than that of PA nets (535.1 kg, 248 individuals). The catch of Pampus argenteus was also greater in PBEAS nets with increases of approximately 51.0% in number and 35.8% in weight although the difference in total catch weight between the two net types was not statistically significant (Wilcoxon signed-rank test, p = 0.25). The size distribution of Pampus argenteus ranged from 12 to 28 cm fork length (FL) for both nets, with PBEAS nets showing more individuals particularly in the 16 – 20 cm range. Bycatch patterns were similar between the two gears where Chelidonichthys kumu, white Argyrosomus argentatus, and Zeus faber identified as dominant species. These findings clearly demonstrate the practical potential of PBEAS biodegradable gillnets and highlight their promise as an alternative to PA nets for promoting sustainable fisheries.

전기추진 선박의 추진축계 이상상태는 심각한 선박 운항 장애를 초래할 수 있으므로, 추진 시스템의 상태를 정확히 진단하고 사전에 예방 유지보수를 수행하는 Prognostics and Health Management(PHM) 기술의 필요성이 증가하고 있다. 본 연구에서는 전기추진 선박 의 추진축 이상상태를 조기에 감지하고 진단하기 위하여 진동 데이터를 기반으로 한 머신러닝 기반 PHM 시스템의 개발과 성능 평가를 수행하였다. Land-Based Testing System(LBTS) 시스템에서 수집된 정상 상태와 축 정렬 이상 상태(0.5 mm, 1.0 mm, 1.5 mm)의 진동 데이터를 활용하여 데이터 전처리 및 특성 추출을 수행하였다. 연구에서는 Fully Connected Neural Network(FCNN) 및 Convolutional Neural Network(CNN)을 적용하여 이상 상태를 진단하는 모델을 개발하고 비교 분석하였다. FCNN 기반 모델은 단순한 구조로 빠른 학습이 가능 하여 실시간 모니터링에 적합한 반면, CNN 모델은 미세한 상태 변화를 효과적으로 탐지하는 데 탁월한 성능을 보였다. 성능 평가 결과 FCNN 모델은 평균 95% 이상의 정확도를 나타냈으며, CNN 모델은 이보다 더욱 향상된 성능을 제공하였다. 본 연구를 통해 개발된 진동 기반 PHM 시스템은 전기추진 선박 추진축 이상상태를 효과적으로 조기에 진단할 수 있는 능력을 입증하였다. 이러한 연구 성과는 전기 추진 선박의 안전하고 효율적인 운항을 위한 신뢰성 높은 유지보수 전략 수립에 중요한 기여를 할 것으로 기대된다. 향후 연구로는 데이 터 품질 개선 및 추가적인 딥러닝 모델 적용을 통한 성능 향상을 목표로 한다.

Permeable blocks are effective in improving urban water circulation and alleviating heat islands and floods. However, they cause environmental problems owing to their dependence on cement and natural aggregates. In this study, a permeable block was developed, and its performance was verified using ferronickel slag (FNS) as a substitute. The block applied with FNS met the KS F 4419 standard, and an average flexural strength of 4 MPa and a permeability coefficient of 0.1 mm/s or more were secured. This study confirmed that natural aggregate collection could be suppressed, resource efficiency could be improved, greenhouse gas reduction could be achieved, and high value-added industrial byproducts could be used.

This study investigates the seismic performance of beam-column connections using Thin-Walled Steel Composite (TSC) beams and Prestressed Reinforced Concrete (PSRC) columns. TSC beams are constructed from U-shaped thin steel plates that are filled with concrete, allowing for composite action with slabs through the use of shear connectors. They are widely applied in industrial buildings due to excellent strength, stiffness, and constructability. However, slender web plates are prone to local buckling, which may compromise their performance during seismic events. To mitigate this issue, internal supports have been introduced to enhance web stability and concrete confinement. Cyclic loading tests on three specimens—with and without internal supports—demonstrated that the supports increased moment capacity, improved energy dissipation, and effectively reduced buckling. Even slender sections demonstrated performance comparable to that of compact sections. All specimens reached peak strength at a 2.44% rotation angle, with damage localized near the supports. A practical connection detail was also proposed, taking into account constructability and structural reliability. The results provide valuable guidance for the seismic design of composite systems in large-scale structures.