본 연구는 EO/IR 마스트가 장착된 수중운동체에 작용하는 유체역학적 하중을 정수 및 파랑 환경에서 규명하는 것을 목적으로 한다. 수치해석은 Reynolds-Averaged Navier-Stokes(RANS) 방정식과 Volume of Fluid(VoF) 기법을 적용하여 수행하였으며, 마스트 및 선체에 작용하는 항력을 계산하였다. 계산 결과는 Morison 방정식과 Stokes 점성모델을 기반으로 한 이론 해석과 비교·검증되었다. 수치해석 결과 는 이론식과 비교하여 평균 상대 오차 5% 이내, 최대 오차 10% 미만의 범위에서 일치하였으며, 상관계수는 0.95 이상으로 나타나 정량적 으로 높은 정합성을 확인하였다. 파랑에 의한 힘의 변동은 파랑 고도 변화에 따른 정수압 분포의 변화가 지배적인 요인으로 분석되었으 며, 동수압 성분은 전체 파력 대비 10% 미만으로 제한적인 영향을 미치는 것으로 나타났다. 이러한 결과는 마스트 설계 시 파랑 영향 고 려의 필요성을 강조하며, 구조적 안정성 확보와 구동기 및 지지부의 과부하 방지를 위한 설계 지침을 제시한다. 본 연구는 향후 불규칙 파랑 조건 및 유체–구조 연성 해석으로 확장될 수 있는 기초자료로 활용될 수 있으며, 수중운동체 마스트 시스템의 신뢰성과 안전성 향 상에 기여할 것으로 기대된다.

Background: Real-time ergonomic risk assessment in manufacturing environments is challenged by severe class imbalance in high-risk postures and the need for deployment-efficient models. Conventional oversampling techniques may violate biomechanical constraints, limiting their suitability for human motion data. Objectives: This study aimed to compare multiple machine learning models for real-time ergonomic risk assessment while addressing data imbalance using biomechanically appropriate learning strategies and evaluating both predictive performance and deployment efficiency. Design: Comparative study. Methods: A large-scale workplace safety dataset comprising image-based skeletal keypoints was analyzed. To mitigate class imbalance without generating biomechanically implausible samples, cost-sensitive learning and focal loss were employed instead of synthetic oversampling. Subject-wise data splitting was applied to prevent data leakage. Five model families, including Random Forest, convolutional neural networks, and a lightweight graphbased network, were evaluated using accuracy, F1-score, area under the receiver operating characteristic curve (AUC), and high-risk recall. Statistical significance was assessed using bootstrap confidence intervals and McNemar and DeLong tests. Results: The lightweight graph-based model demonstrated competitive classification performance while maintaining reduced computational complexity. Although none of the models achieved the predefined high-risk recall threshold, statistically significant performance differences were observed across model families. Conclusion: The findings suggest that biomechanically informed imbalance handling improves methodological validity in ergonomic risk assessment. While deployment feasibility appears promising, further empirical validation on edge hardware is required.

교량 구조물은 강진 발생 시에 구성요소들간에 복잡한 비선형 거동을 보이기 때문에 내진성능평가를 위해서는 동적 비선형 거동 을 효과적으로 반영할 수 있는 증분동적해석(IDA)방법이 유리하다. 납-고무받침(LRB)과 탄성받침(RB)을 가진 두 가지 예제교량에 대하여 근거리 및 원거리 지진 각각 40개씩을 사용하여 0.01g~5.0g 범위에 지진세기에 대하여 증분동적해석을 수행하여 지진응답을 평가하였다. IDA 방법에 의해 40개의 지진세기와 교각의 변위비 사이의 관계곡선을 구하였다. 이 관계곡선에서 총 40개 지진세기의 교차점에 해당하는 지진응답들의 분포를 히스토그램으로 전환하여 손상상태 한계값의 초과확률을 구하여 지진취약도 평가하였다. 40개 점들의 지진취약도로부터 하나의 중앙값과 대수표준편차 함수로 평가하는 방법을 제시하여 최종적인 지진취약도 함수를 평가 하였다. 지진취약도 해석방법 중에서 가장 대표적으로 많이 사용되는 확률론적 지진요구도 모델(PSDM)을 이용하여 동일한 해석조 건에 대하여 지진취약도를 평가하였고, 이를 IDA방법에 의한 지진취약도 함수와 비교한 결과 유사한 경향을 나타냄을 알 수 있었다.

본 연구에서는 3D 스캐닝 기반의 역설계 기술과 전과정평가(Life Cycle Assessment, LCA)를 통합하여 실제 생산 공정의 특성을 반영한 디지털 모델을 구축하고 이를 기반으로 선박의 성능과 환경성을 동시에 개선하는 지속가능한 설계 방법을 제안하였다. 연구 대상 인 8m급 복합재료 소형 선박을 3D 스캐닝하여 초기 디지털 모델을 생성하였으며 이후 설계 중량과 실제 측정 중량 간의 차이를 규명하기 위해 수적층(hand lay-up) 공법의 제조 공차, 재료 겹침, 불균일한 수지 분포 등 생산 현장의 비정형적 요소를 모델에 정량적으로 반영하여 실제 제작 상태에 근접한 역설계 모델을 개발하였다. 이를 기준으로 성능 개선 요구사항을 만족시키는 최종 설계안을 도출하고 두 모델 에 대한 전과정평가를 수행하여 환경 영향을 비교 분석하였다. 그 결과 생산 공정의 특성을 고려한 역설계 모델은 실제 선박의 중량과 0.02% 이내의 오차를 보여 높은 정확도를 입증하고 이를 바탕으로 개선된 최종 설계안은 역설계 모델 대비 평균 1.94%의 환경 영향 감소 효과를 보였으며 폴리에스터 수지가 전체 환경 부하의 핵심 요인임을 정량적으로 식별하였다.

Speed management in Korea currently emphasizes the setting of speed limits and controlling vehicle speeds to align with these standards. However, monitoring safe and stable speeds tailored to specific road sections is essential for enhancing pedestrian safety in urban areas. In this study, a crash frequency model was developed to define the speed stability range and identify the critical threshold at which the crash frequency changes rapidly. This threshold serves as a reference point for assessing the speed stability levels. Individual vehicle trajectory data collected from 20 road segments in Daejeon-si were used to calculate the speed-related safety evaluation indicators that served as input variables for the safety model. The speed stability range calculation incorporates speed-related indicators and road facility data from Daejeon-si, allowing the model to consider the surrounding infrastructure. The findings revealed that intersections and crosswalks are positively correlated with cumulative crash occurrences. Crash frequency predictions showed higher crash likelihoods at average driving speeds below 30 km/h, indicating that congested conditions at intersections or at peak times necessitate increased safety management. Measures for maintaining safe and appropriate vehicle speeds within identified safe ranges are critical. The speed stability range calculation methodology provides a foundation for establishing traffic safety management strategies that focus on speed control in urban areas. These results can guide the development of targeted safety interventions that prioritize pedestrian protection and optimize safe driving speeds across various road segments.

해상 운송 시스템에 사이버 위협이 증가함에 따라, 안전한 운항을 보장하기 위한 사이버 복원력의 필요성이 부각되고 있다. 특 히, 자율운항선박과 같은 고도의 기술 융합이 요구되는 스마트선박은 기존보다 더 광범위한 사이버 공격 표면을 가지게 되어 이에 대한 리스크 관리가 필수적이다. 본 연구에서는 스마트선박의 사이버 복원력을 평가하기 위해 국제 표준인 IACS UR E26, E27, IEC 62443, NIST SP 800-160을 분석하고, 이를 통해 스마트선박의 선종과 자율화 수준에 따른 사이버 리스크 평가 및 각각의 리스크에 맞는 복원력 모델 개념을 설계하였다. 특히, 선박의 자율화 수준이 높아질수록 사이버 리스크가 커지므로 이를 반영한 맞춤형 대응 전략을 도출하고 스마트 선박의 사이버 복원력 향상을 위한 성숙도 모델을 제안했다.

Maintaining sea superiority through successful mission accomplishments of warships is being proved to be an important factor of winning a war, as in the Ukraine-Russia war. in order to ensure the ability of a warship to perform its duties, the survivability of the warship must be strengthened. In particular, among the survivability factors, vulnerability is closely related to a damage assessment, and these vulnerability data are used as basic data to measure the mission capability. The warship's mission capability is usually measured using a wargame model, but only the operational effects of a macroscopic view are measured with a theater level resolution. In order to analyze the effectiveness and efficiency of a weapon system in the context of advanced weapon systems and equipments, a warship's mission capability must be measured at the engagement level resolution. To this end, not the relationship between the displacement tonnage and the weight of warheads applied in the theater level model, but an engagement level resolution vulnerability assessment method that can specify physical and functional damage at the hit position should be applied. This study proposes a method of measuring a warship’s mission capability by applying the warship vulnerability assessment method to the naval engagement level analysis model. The result can be used as basic data in developing engagement algorithms for effective and efficient operation tactics to be implemented from a single unit weapon system to multiple warships.

of hazardous risk factors, risk estimation and determination steps by reflecting the trend of overseas risk assessment. METHODS : In deriving, estimating and determining risk factors, comparing the procedures presented by the ILO with the domestic guidline to find out the differences in procedural. and, According to the domestic manual, after setting the criteria for determining a deterministic perspective, analyze the risk assessment data of a specific domestic company and three overseas risk assessment research data to analyze the differences in methodology domestic and abroad. RESULTS : Within the country, there is a possibility that a deterministic view may be applied to all stages of procedure, and certain corporate data to the risk estimation and determination stage. In the case of overseas, the trend of applying deterministic perspectives to the risk determination stage was confirmed. CONCLUSIONS : Present the need for a standard model for improving deterministic methods in the other two stages, excluding risk determination in the domestic evaluation procedure.

Velvet antler is widely used as a traditional medicine, and numerous studies have demonstrated its tremendous nutritional and medicinal values including immunity-enhancing effects. This study aimed to investigate different deer velvet extracts (Sample 1: raw extract, Sample 2: dried extract, and Sample 3: freeze-dried extract) for proximate composition, uronic acid, sulfated glycosaminoglycan, sialic acid, collagen levels, and chemical components using ultra-performance liquid chromatography-quadrupole-time-of-light mass spectrometry. In addition, we evaluated the cytotoxic effect of the deer velvet extracts on BV2 microglia, HT22 hippocampal cells, HaCaT keratinocytes, and RAW264.7 macrophages using the cell viability MTT assay. Furthermore, we evaluated acute toxicity of the deer velvet extracts at different doses (0, 500, 1000, and 2000 mg/kg) administered orally to both male and female ICR mice for 14 d (five mice per group). After treatment, we evaluated general toxicity, survival rate, body weight changes, mortality, clinical signs, and necropsy findings in the experimental mice based on OECD guidelines. The results suggested that in vitro treatment with the evaluated extracts had no cytotoxic effect in HaCaT keratinocytes cells, whereas Sample-2 had a cytotoxic effect at 500 and 1000 μg/mL on HT22 hippocampal cells and RAW264.7 macrophages. Sample 3 was also cytotoxic at concentrations of 500 and 1000 μg/mL to RAW264.7 and BV2 microglial cells. However, the mice treated in vivo with the velvet extracts at doses of 500–2000 mg/kg BW showed no clinical signs, mortality, or necropsy findings, indicating that the LD50 is higher than this dosage. These findings indicate that there were no toxicological abnormalities connected with the deer velvet extract treatment in mice. However, further human and animal studies are needed before sufficient safety information is available to justify its use in humans.

This study proposes a methodology for assessing seismic liquefaction hazard by implementing high-resolution three-dimensional (3D) ground models with high-density/high-precision site investigation data acquired in an area of interest, which would be linked to geotechnical numerical analysis tools. It is possible to estimate the vulnerability of earthquake-induced geotechnical phenomena (ground motion amplification, liquefaction, landslide, etc.) and their triggering complex disasters across an area for urban development with several stages of high-density datasets. In this study, the spatial-ground models for city development were built with a 3D high-precision grid of 5 m x 5 m x 1 m by applying geostatistic methods. Finally, after comparing each prediction error, the geotechnical model from the Gaussian sequential simulation is selected to assess earthquake-induced geotechnical hazards. In particular, with seven independent input earthquake motions, liquefaction analysis with finite element analyses and hazard mappings with LPI and LSN are performed reliably based on the spatial geotechnical models in the study area. Furthermore, various phenomena and parameters, including settlement in the city planning area, are assessed in terms of geotechnical vulnerability also based on the high-resolution spatial-ground modeling. This case study on the high-precision 3D ground model-based zonations in the area of interest verifies the usefulness in assessing spatially earthquake-induced hazards and geotechnical vulnerability and their decision-making support.