This study conducted an exploratory single-case study on a public maritime education agency (Agency A) to examine the practical reorganization process of the business continuity management system (BCMS) training framework. By analyzing risk assessment (RA) data (2024-2026) and simulation exercise results (2023-2026), this study explored changes in organizational risk perception and the subsequent evolution of training strategies. The RA analysis revealed a shift in priority threats-from typhoons to safety accidents, extreme heat, and technical disruptions-reflecting recent changes in the climate and regulatory environments. Furthermore, a review of early simulation exercises highlighted the structural limitations of conventional training where repetitive, full-staff evacuation drills and uniform tabletop discussions induced participant fatigue and lowered practical engagement. To address these limitations, the institution implemented a two-track framework, separating executive decision-making tabletop exercises from action-oriented practical drills for field staff. For example, field staff engaged in practical drills involving the direct operation of emergency equipment in cooperation with external specialized agencies. Rather than statistically proving causal effectiveness, this study illustrates how aligning customized scenarios with RA results and restructuring emergency organizations to fit specific roles can improve the practical relevance of BCMS exercises. It provides practical implications for public institutions seeking to establish a flexible and sustainable training feedback loop.

This study investigated context-dependent characteristics of vocalizations in captive bottlenose dolphins (Tursiops truncatus) under different behavioral situations in Korea. The experiment was conducted on July 21, 2025, at the Whale Ecology Experience Center in Ulsan, Korea, involving four captive bottlenose dolphins housed together in a single tank. Four experimental conditions were established: (1) a normal condition without external disturbance, (2) a feeding condition in which a trainer threw food into the tank, (3) a training condition involving responses to trainer signals, and (4) a toy-provided condition. Dolphin vocalizations were recorded for a total of 90 minutes using an Aquafeeler IV A and AQH-200D hydrophone (10 Hz-200 kHz, sensitivity -220 dB re 1 V/μPa) while behavioral data were simultaneously collected using tank monitoring cameras. Acoustic analyses were conducted using PAMGuard software. A total of 197 whistles and 378 buzzes and burst-pulses were recorded during the experiment. In the normal condition, dolphins swam freely and predominantly produced whistles within a frequency range of 6.81-23.82 kHz. During the feeding condition, the production of whistles, buzzes, and burst-pulses decreased while click trains associated with food searching behavior were mainly observed, typically lasting 0.9-1.8 seconds. In the training condition, dolphins primarily produced buzzes and burst-pulses, often accompanied by low-frequency tonal components (1.55 – 8.13 kHz) in response to trainer signals. In the toy-provided condition, dolphins produced clicks associated with object exploration along with buzzes and burst-pulses ranging from 1.3 to 10.8 kHz. Whistles were most frequently recorded in the normal condition accounting for 72.5% of total whistle occurrences whereas buzzes and burst-pulses were most frequent in the toy-provided condition (51.1%). These results demonstrate that bottlenose dolphin vocalizations vary systematically according to behavioral context, suggesting that vocalization frequency and patterns should be useful indicators for inferring behavioral states and have potential applications in passive acoustic monitoring and biological monitoring technologies.

This study conducts a precise analysis of the formation process of the Eonmun Spelling System (1930) by examining its primary source materials: the Eonmun Spelling System (Internal Draft) (1928) and the Eonmun Spelling System (Base Text of the Revision) (1929). The 1930 orthography served as a significant turning point in the history of Korean writing systems by establishing the foundation for morphophonemic spelling through the expansion of the final consonant system and refinement of syllabic separation rules. Notably, this research uncovers and compares the Japanese version of the Base Text of the Revision, which had previously been studied only through Korean translations in newspapers such as Dong-a Ilbo. The findings reveal that these translations were not mere renditions, but intentional revisions reflecting the Deliberation Committee’s discussions and the translators’ normative orientations. Furthermore, by analyzing handwritten notes in the mimeographed original of the Base Text, this paper reconstructs debates on core issues, such as morphological representation, initial sound rules, fortis, and the epenthetic sound notation. Ultimately, this study illuminates the dynamic process through which the 1930 orthography emerged from negotiations between the government-general’s policy demands and the academic aspirations of Korean linguists.

Demand for low-carbon fuels is increasing in the aviation sector due to the expansion of global carbon neutrality policies, and sustainable aviation fuel (SAF) is attracting attention as a promising alternative in the aviation industry, where electrification and hydrogen application are difficult. This study is a basic study considering the possibility of aviation fuel conversion, and a hydrocarbon-based biodiesel was prepared through deoxygenation by selecting oleic acid with a free fatty acid structure as a raw material. The conversion rate and selectivity were analyzed through optimization of reaction conditions, and the possibility of use as aviation fuel was basically reviewed through evaluation of fuel characteristics. This study presents basic data for the conversion of free fatty acid-based biodiesel to aviation fuel.

Injection molds, composed of components such as upper and lower cores, mold bases, pins, and cooling channels, serve as the primary tooling for manufacturing plastic products. Despite the often simple geometry of molded products, the configuration and design of mold components remain highly complex, making the technical expertise and accumulated know-how of mold designers essential. However, the mold industry is facing increasing difficulties due to the discontinuation of academic programs dedicated to mold design, the aging of experienced designers, and the lack of incoming skilled personnel. To address these challenges, research on automating mold design has continued, and recent advancements in artificial intelligence (AI) have accelerated efforts to internalize expert knowledge through a variety of computational approaches. In this study, we conducted foundational research aimed at constructing a DT-AX platform capable of handling multiple domains by implementing and modularizing diverse processes within a digital-twin (DT) environment and integrating AI modules specialized for each process. Given the input dimensions of a bottle-cap model (diameter and height), the simplified outer dimensions of a core mold were predicted and subsequently used to generate a 3D model. The resulting STEP file was verified to be compatible with commercial CAD and simulation software. Overall, the results demonstrate the feasibility of implementing an automated mold-design module within a digital-twin environment. Future work will focus on diversifying design variables and increasing geometric complexity to develop modules that more closely approximate real-world mold design.

Photocurable polymer components fabricated via 3D printing often exhibit rough surfaces and visible layer marks due to the inherent characteristics of additive manufacturing. Consequently, post-processing is frequently required to improve the external appearance of the final product. Since surface finishing is typically performed through machining, the appropriate selection of machining parameters is critical to prevent thermal-induced surface damage, particularly given the low heat-deflection temperature of polymer materials. Moreover, the mechanical properties of photocurable resins vary depending on resin composition and curing conditions, which also affect machinability. Therefore, baseline machining experiments are necessary to determine the optimal post-processing conditions for printed components. In this study, machining experiments were conducted on polymer specimens fabricated using a DLP (Digital Light Processing) system by varying spindle speed, feed rate, and depth of cut to optimize surface finishing conditions. The results indicate that the most improved surface roughness, approximately Ra 0.4 μm, was achieved under the conditions of 20,000 RPM spindle speed, 60 mm/min feed rate, and 100 μm depth of cut. This represents a 14-fold improvement compared to the pre-machining surface roughness. These optimized conditions are expected to be applied to the post-processing of porous scaffold core molds in future work.

시멘트 산업은 막대한 에너지 소비와 이산화탄소 배출을 동반하는 대표적인 자원⋅환경 부담 산업으로 알려져 있으며, 이를 대체하기 위한 혼합재 연구가 활발히 이루어지고 있다. 특히 금속 광미(metal mine tailings)는 광산 개발 및 선광 과정에서 대량으로 발생하지만 활용도가 낮아 환경적 문제를 야기하고 있다. 이러한 배경에서 광미를 시멘트 혼합재로 적용하는 연구는 폐기물 저감과 자원 재활용을 동시에 달성할 수 있는 방안으로 주목받고 있다. 이에 본 연구에서는 국내에서 발생한 금속 광미를 조건별로 혼합한 모르타르 공시체를 제작하여 압축강도, 수화반응, 미세구조 및 기공율 변화를 평가하였으며, 이를 통해 금속 광미의 시멘트 혼합재로서 의 적용 가능성을 도출하였다.

In 2015, the safety refresher training system for seafarers was reformed with the aim of strengthening practical skills. However, a failure to forecast demand led to a chronic backlog of trainees. Furthermore, the uniform application of merchant vessel standards (STCW) to fishing vessels (STCW-F) created a qualitative problem, undermining the effectiveness of the education. This study aims to diagnose these issues and propose effective improvement measures. This research employed a mixed-methods approach. First, a comparative analysis was conducted between international conventions (STCW and STCW-F) and domestic regulations, institutional standards, and curricula. Second, an empirical analysis was performed through a survey of 220 merchant and fishing vessel seafarers, which was supplemented by in-depth interviews. The analysis revealed several critical gaps. The domestic legal framework does not distinguish between STCW and STCW-F and the curriculum is heavily biased toward theory, failing to meet international practice-oriented competency standards. The survey and interview results confirmed that the current fits all training is severely misaligned with the operational realities of fishing vessels, which have different equipment and environments. Based on these findings, this study proposes three prolonged improvement plans. First, the curriculum should be dualized to reflect the distinct characteristics of merchant and fishing vessels. Second, a hybrid training model that combines mandatory shore-based training for high-risk drills with flexible onboard training for basic skills should be introduced. Third, facility standards for training institutions should be converted from rigid mandates to flexible guidelines. These measures are expected to resolve the chronic training backlog and enhance the practical emergency response capabilities of all seafarers.

This study addresses the increasing damage to national heritage due to climate change by analyzing the current use of terms that describe deterioration damage phenomena in wooden architectural heritage, and proposes a framework for defining and systematizing these terms. The research found that inconsistencies in the use of terms for the same deterioration damage phenomena and unclear definitions in regular heritage survey and monitoring reports cause confusion in data analysis and accumulation. Consequently, this study followed ISO 704 and KS standards to understand the relational system of terms, proposing a hierarchical structure with "deterioration damage" as the top concept and systematically organizing its sub-concepts. Specific terms such as "crack," and the Korean-originated terms "Gallem" and "Apgoe", were analyzed to establish clear definitions and build a system based on their conceptual properties. The study is expected to enhance the effectiveness of heritage conservation and management, ensure consistency in terminology usage among researchers, and support the establishment of data-based scientific conservation policies. Future research will focus on developing practical standardization strategies for deterioration damage terminology through in-depth discussions with field experts and conducting long-term national-level studies.

Various vibrations occur while a ship is in operation. In the propulsion shaft systems of medium and small-sized vessels, it is common to install elastic couplings to prevent fluctuating torque from being directly transmitted to the reduction gear system and to avoid damage caused by torsional vibrations. However, the majority of elastic couplings are currently imported. The engine speed was gradually increased during the coupling test, while the vibrations were measured. At the point of maximum output, the engine speed was maintained at a constant level to observe the structural vibrations of the engine. This study aims to localize the production of elastic couplings by addressing the issue from the perspectives of torsional and structural vibrations to verify their operational performance.

The International Maritime Organization (IMO) is promoting the transition to eco-friendly fuels such as hydrogen and ammonia, with the goal of achieving net-zero greenhouse gas emissions in the shipping sector by 2050. Hydrogen does not emit greenhouse gases, but it must be stored at an extremely low temperature of -253°C when stored as a liquid. 316L stainless steel is mainly used as a tank material to store liquid hydrogen. FCAW (Flux Cored Arc Welding) is known for its excellent weldability with 316L stainless steel, and it is particularly suited for welding thick metals efficiently, making it an ideal choice for storage tank welding. Finite Element Method (FEM) analysis can simulate the thermal and mechanical deformations occurring during welding with high precision, allowing for accurate prediction of deformation patterns and the derivation of optimal welding conditions. This ensures the stability and quality of the structure while reducing costs. In this study, FCAW butt welding was performed on 316L stainless steel, followed by cross-sectional observation and deformation measurement of the weld area. Based on the cross-sectional observation, a 3D FE model was designed, and heat transfer analysis was conducted. Subsequently, thermo-mechanical analysis was carried out to predict welding deformation.

Magnesium alloys, among various non-ferrous metals, are utilized in diverse fields from the automotive industry to aerospace due to their light weight and excellent specific strength. In the previous Part I study, fiber laser BOP experiments were conducted to derive basic welding characteristics and appropriate bu竹 welding conditions. Subsequently, in the Part II experiment, butt welding was performed, and through tensile tests, hardness tests, and cross-sectional observations, it was found that at laser power of 2.0 kW and welding speed of 50 mm/s, 93% of the base metafs tensile strength and 63.4% of its elongation could be achieved. In this Part III experiment, the microstructures of the base metal and the center of the weld were observed in butt-welded specimens. Through this, laser power and welding speed, on the mechanical behavior and microstructure of magnesium alloys were analyzed

This study aims to establish the concept of fish welfare and develop guidelines for its implementation in South Korean aquaculture. As global awareness of animal welfare grows, scientific evidence shows that fish are sentient beings capable of experiencing pain and that stress has led to increased demand for welfare standards in aquaculture. International organizations like WOAH and the EU have set welfare standards for farmed fish, emphasizing their importance for health, productivity, and food safety. However, in South Korea, fish welfare is still an emerging concept with limited research. This study systematically defines fish welfare, assesses its feasibility in domestic aquaculture, and proposes guidelines tailored to local conditions. The findings highlight the need for gradual implementation, considering the unique biological and environmental factors in fish farming.