The use of aluminum-based hybrid metal matrix composite (HMMC) materials, especially in engine components like pistons, is intended to improve wear resistance and overall performance. Crucial tribological indicators, such as wear and friction coefficients, underscore the significance of these materials. However, present aluminum alloys have limited wear because of clustered reinforced particles and relatively high coefficients of thermal expansion (CTE), resulting in inadequate anti-seizure properties during dry sliding conditions. This research introduces a novel “Hybrid Metal Matrix Composite of Al7068 Reinforced with Fly Ash-SiC-Al2O3”. Al7068 is employed for its superior strength-to-weight ratio and specific modulus, which is ideal for components exposed to cyclic loads and varying temperatures. The integration of fly Ash (FA), silicon carbide (SiC), and alumina (Al2O3) as reinforcements enhances wear resistance, diminishes particle clustering, improves stiffness, mitigates CTE discrepancies, and fortifies the composite against strain and corrosion, thereby enhancing its overall performance. The Stir-casting method was used with optimized reinforcement percentages (10 % total), and comprehensive evaluations through wear tests and mechanical property analyses determined the composite's optimal composition. The proposed HMMC variant with the most suitable reinforcement percentage exhibited enhanced engine piston functionality, reduced wear, low deformation of 0.20 mm, and a comparatively higher ultimate tensile strength of 190 megapascals (Mpa).

본 연구는 중부지역에서 사료작물인 수단그라스 교잡종(Sorghum x Sudangrass hybrid, SX-17)의 기후 영향에 대한 취약성을 평가하고 생산성에 영향을 미치는 주요 기후 요인을 규명하고자 2017년부터 2018년까지 충청북도 충주와 충청남도 청양에서 현장 실험을 수행하였으며, 기후 취약성은 농촌진흥청에서 정의한 지수를 활용하여 평가하고 기온 및 강수량 자료는 기상청에서 제공받았다. 2018년의 수단그라스 교잡종의 생초 및 건물 수량은 고온과 가뭄 스트레스로 인해 2017년에 비해 현저히 감소하였고, 두 지역 모두 2010년 이후 기후 취약성 증가 추세를 보였으며 2018년에 최대값인 0.7에 도달하였고, 이러한 결과는 극한 기상 현상이 사료작물 생산성에 부정적인 영향을 미친다는 점을 부각시 키며 기후영향 취약성 평가는 기후변화 시나리오 하에서 효과적인 농업 적응 전략 수립을 위한 기초자료로 활용될 수 있음을 시사한다.

To support the International Maritime Organization’s (IMO) 2050 greenhouse gas reduction targets, hybrid propulsion energy management systems (EMS)—which integrate multi-energy coordination and dynamic scheduling—have become a critical pathway for enabling low-carbon transitions and improving energy efficiency in the maritime sector. This paper conducts a comprehensive and structured analysis of EMS technologies applied to ship hybrid propulsion systems. It evaluates the functional roles of EMS under varying system architectures, synthesizes mainstream energy management strategies, and identifies current technological bottlenecks, thereby contributing theoretical foundations for the green transformation of the shipping industry. The study first examines representative hybrid propulsion architectures, detailing their technical characteristics to clarify the functional positioning and optimization priorities of EMS in each configuration. It then reviews prevailing energy management and control strategies, with a focus on their integration with artificial intelligence (AI) and the emergence of adaptive and data-driven approaches. Finally, the paper identifies key challenges in hybrid propulsion EMS, proposes future research directions, and offers practical recommendations to support the advancement and implementation of intelligent energy management technologies in maritime applications.

As a technical alternative to strengthening global environmental regulations and increasing domestic oil costs due to the climate crisis, the government (Ministry of Oceans and Fisheries) has been implementing the technological development of hybrid commercial fishing boats since 2021. This study empirically analyzes the awareness of fisheries workers (n=568) and fisheries-related stakeholders (n=151) regarding the hybrid fishing boats and evaluates strategic competitive advantages of the boat-building technology using the VRIO (Value, Rarity, Inimitability, Organization) framework. The Korean fisheries sector currently faces worsening business conditions due to structural challenges such as resource depletion (57.6%), labor shortages (30.8%), and rising fuel costs (81.5%). Consequently, the tax-free fuel subsidy program has emerged as a critical factor for sustaining fisheries operations, with 91.9% of fishers identifying the program as essential for business stability and 63.6% indicating they would cease operations if the program were abolished. Under these circumstances, hybrid electric vessels are gaining attention as a promising alternative for reducing fuel costs, with 32.2% of respondents expressing a willingness to adopt such vessels. Conditional demand analysis revealed that 37% of fishers showed willingness to purchase if fuel savings reached 30~50%, with an average acceptable price increase of 16.8% over conventional boats and an average desired government subsidy rate of 56.3%. The VRIO results show that the technology holds competitive advantages in value, rarity, and inimitability, but falls short in the organization dimension. The results indicate the need for improvements in institutional infrastructure such as dedicated organizations, process standardization, and a structured supply system.

북한의 새로운 시위방식인 오물·쓰레기 풍선 살포와 관련해 한국군은 당시 어떠한 억제 전략을 선택했고, 최종 판단을 내리는 과정에서 고려 가능한 옵션 은 무엇이었을까? 이 글은 이를 학술적으로 설명할 수 있는 이론과 뒷받침할 수 있는 근거가 필요하다는 문제의식과 함께 한미 양국 군이 최근 참고한 논문 으로 Monaghan(2022)의 “하이브리드 위협 억제 방안”이라는 이론을 소개하고 북한의 오물·쓰레기 풍선 살포 행위를 ‘하이브리드 위협’으로 규정한다. 다음으 로, 하이브리드의 위협 발생 단계가 ‘도발 3단계’로 진입했으며, 그 강도가 ‘고 강도’로 누적 접근하고 있음을 확인하였다. 이에 따라 한국군이 이론적으로 선 택할 수 있는 억제 전략은 응징적 억제, 절대적 억제, 맞춤형 억제, 확장 억제 (요청)로 추릴 수 있으나, 실제로는 위협 강도에 따라 개별 대응하는 ‘맞춤형 억제 전략’ 그리고 동맹국인 미국에 ‘확장 억제를 요청’하는 전략을 선택했음을 알 수 있다. 아울러, 중국 정찰풍선·추정체에 대한 미국의 고고도 격추 대응 사 례를 함께 살펴봄으로써 일각에서 주장하는 ‘원점 타격’ 방식이 어려운 근거를 찾게 된다. 마지막으로, 한국군이 선택한 맞춤형 억제 전략의 시행을 극대화하 고 향후 북한의 다양한 하이브리드 위협에 대한 대비와 대응 조치의 적절성 및 신뢰성을 입증하기 위해서는 실효성 있는 대안이 추가로 필요하다고 주장한다. 구체적으로는, 위협 강도의 한계선을 결정지을 ‘정성적 기준’과 위협 행위자의 ‘고의성을 입증하는 방법’의 마련, 종합대책을 세울 주체로서 ‘컨트롤타워’의 필 요성, 외교부·통일부·법무부 등 각 정부 부처의 개별 특성에 맞는 다각적 노력 을 강조한다.

정확한 선박 항적 예측은 선박의 충돌 회피 전략 수립과 자율운항 선박의 안전 운항에 중요한 요소이다. MMG(Maneuvering Modeling Group) 모델이나 CFD(Computational Fluid Dynamics)를 활용하여 선박 항적을 계산할 수 있지만, 계산을 위한 선박의 정확한 계 수등을 확보하는 것은 현실적으로 어렵다. 이에 대한 대안으로, LSTM(Long Short-Term Memory)과 같은 인공지능을 활용한 항적 예측 연 구가 진행되고 있다. 그러나 LSTM 단독으로는 선박의 복잡한 비선형적 움직임을 완벽히 예측하는데 한계가 있다. 예측 정확도를 향상 시키기 위해 본 연구에서는 STL-CNN-LSTM 하이브리드 모델을 제안한다. 이 모델은 STL (Seasonal and Trend decomposition using Loess)을 이용한 데이터를 분해하고, CNN(Convolutional Neural Network)을 활용한 데이터의 특징 추출, 그리고 LSTM을 통한 학습이 이뤄진다. 이 연구는 CNN-LSTM에 비해 얼마나 더 높은 항적 예측도를 보여주는지 비교 분석한다. 분석 결과, STL-CNN-LSTM 모델은 CNN-LSTM보 다 우수한 예측 성능을 보이며, 예측 오차는 1~5미터 범위 내에 있는 것으로 나타났다. 이러한 연구 결과는 정밀한 충돌 회피 전략 개 발에 기여할 수 있으며, 향후 연구에서는 실무 적용을 위한 충돌회피 모델의 설계 고도화 연구에 적용될 것이다.

A hybrid energy harvester that consisted of thermoelectric (TE) composite film and electrospun piezoelectric (PE) polymeric membranes was constructed. TE composites were fabricated by dispersing inorganic TE powders inside polyvinylidene fluoride elastomer using a drop-casting technique. The polyvinylidene fluoride-trifluoroethylene, which was chosen due to its excellent chemical resistance, mechanical stability, and biocompatibility, was electrospun onto an aluminum foil to fabricate the ultra-flexible PE membranes. To create a hybrid energy harvester that can simultaneously convert heat and mechanical energy resources into electricity, the TE composite films attached to the PE membrane were encapsulated with protective polydimethylsiloxane. The fabricated energy harvester converted the outputs with a maximum voltage of 4 V (PE performance) and current signals of 0.2 μA (TE performance) under periodical heat input and mechanical bending in hybrid modes. This study demonstrates the potential of the hybrid energy harvester for powering flexible and wearable electronics, offering a sustainable and reliable power source.

This study aimed to estimate the accumulated temperature requirements for phenological changes in Lilium. Eight cultivars of three lily types were cultivated in open field conditions for phenological observations based on floral organ development. Growing degree days (GDD) requirements for phenological changes were calculated and verified using Lilium LA hybrid ‘Serrada’ under greenhouse conditions. Lilium Oriental hybrids exhibited higher GDD requirements compared to Lilium FA and LA hybrids for their phenological development. Estimations of phenological change dates in greenhouse cultivation were accurate within 1–3 days. These results provide a reliable description for predicting lily development stages across diverse cultivation environments by quantifying the accumulated temperature requirements for key phenological events.

The seismic performance of lead-rubber bearings (LRBs) is significantly affected by both the axial force and loading rate they experience. Accurate assessment of LRBs’ seismic performance, therefore, requires realistic simulation of these forces and rates, as well as of the response of the isolated structure during seismic events. This study conducted a series of real-time hybrid simulations (RTHS) to evaluate the seismic behavior of LRBs in such conditions. The simulations focused on a two-span continuous bridge isolated by LRBs atop the central pier, exposed to horizontal and vertical ground motions. In the RTHS framework, the LRBs were physically tested in the laboratory, while the remainder of the bridge was numerically modeled. Findings from these simulations indicated that the vertical ground motion had a minimal effect on the lateral response of the bridge when isolated by LRBs.

Being in a stable continental region (SCR) with a limited history of instrumentation, South Korea has not collected sufficient instrumental data for data-driven ground motion models. To address this limitation, we investigated the suitability of the hybrid ground motion simulation method that Graves and Pitarka (2010, 2015) proposed for simulating earthquake ground motions in South Korea. The hybrid ground motion simulation method used in this study relies on region-specific parameters to accurately model phenomena associated with the seismic source and the wave propagation. We initially employed relevant models and parameters available in the literature as a practical approach. We incorporated a three-dimensional velocity model developed by Kim et al. (2017) and a one-dimensional velocity model presented by Kim et al. (2011) to account for the crustal velocity structure of the Korean peninsula. To represent the earthquake source, we utilized Graves and Pitarka’s rupture generator algorithm along with a magnitude-area scaling relationship developed for SCR by Leonard (2014). Additionally, we assumed the stress and attenuation parameters based on studies of regional seismicity. Using the implemented platform, we simulated the 2016 Mw5.57 Gyeongju earthquake and the 2017 Mw5.4 Pohang earthquake. Subsequently, we compared results with recorded accelerations and an empirical ground motion prediction equation at strong motion stations. Our simulations had an overall satisfactory agreement with the recorded ground motions and demonstrated the potential of broadband hybrid ground motion simulation for engineering applications in South Korea. However, limitations remain, such as the underestimation of long-period ground motions during the 2017 Pohang earthquake and the lack of a model to predict the ground motion amplification associated with the near-surface site response accurately. These limitations underscore the importance of careful validation and refinement of region-specific models and parameters for practically implementing the simulation method.