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.

현재 도로포장 유지보수 과정으로부터 노화된 폐 아스팔트가 발생하며, 순환 아스팔트로서 재활용하기 위해 아스팔트 오일을 첨가제 등과 함께 혼합하여 노화된 아스팔트의 성상 회복 및 유동성을 개선하여 도로포 장 재료로 활용하고 있다. 또한 아스팔트 오일의 사용은 저온영역의 성능 개선에도 영향을 미쳐 개질아스팔트 제작에도 활용하고 있으며, 개질 아스팔트는 SBS(Styrene Butadiene Styrene), SBR(Styrene Butadiene Rubber)등 고무계열의 폴리머와 오일 등을 원 아스팔트에 혼합하여 아스팔트 바인더의 공용성을 향상시키는 기술로서 폴리머는 아스팔트의 고온 영역의 물성, 오일은 저온영역의 물성을 개선하는데 사용된다. 이 중 폴 리머에 관한 연구는 활발히 이루어지고 있는 반면 아스팔트에 사용하는 오일에 관한 연구는 상대적으로 연 구가 부족한 실정이다. 따라서 오일의 사용으로 인한 아스팔트의 물성 변화에 관한 실험적인 검토가 필요 하다고 판단된다.

온실가스 배출량을 최소화하기 위하여 가열 없이 생산이 가능한 상온 아스팔트 포장 공법도 2000년 초부터 개발되어 활용되고 있으 나, 기술적 한계로 인해 성능 확보가 어려워 대부분 기층용으로 활용중에 있다. 상온 아스팔트 혼합물은 유화아스팔트를 사용하는데 양생하는 동안 혼합물 내부에 있는 물이 증가됨에 따라 혼합물 내부의 높은 공극률이 발생하게 되어 포장의 성능을 확보하는데 한계 가 있다. 따라서 본 연구에서는 유화 아스팔트 내 아스팔트 고형분 함량을 증가시켜 물 함량을 최소화함으로서, 양생시간을 단축하고 낮은 공극률 확보를 통한 상온 아스팔트 혼합물의 성능의 변화를 평가하였다. 시험결과, 고형분 함량이 변화에 따라 공극률 및 간접인 장강도, 터프니스 물성이 변화가 나타났다. 하지만 고함량 고형분의 유화 아스팔트를 상온 아스팔트 혼합물에 적용하기 위해서는 최적 함수비 결정방식 및 양생방식 등에 대한 추가적인 연구가 필요한 것으로 나타났다.

본 연구의 목적은 외국인을 위한 한국어 쓰기 수업에 챗GPT를 활용할 경우 나타나는 학습자의 반응을 관찰하고 이를 있는 그대로 기술함으로 써 생성형 인공지능의 교육적 활용 가능성을 모색하는 데에 있다. 이를 위해 연구방법론으로 질적 사례연구를 선택하였으며 자료의 삼각화를 충 실히 이행하기 위하여 한 학기 동안 학습 결과물, 챗GPT와의 대화 내용, 수업 만족도 등을 수집하였다. 수집 자료를 분석한 결과 형태적 측면에 서는 문법적인 오류를 수정하고, 잘못된 표현을 바로잡는 데 챗GPT를 유용하게 활용하였으며 어휘적 측면에서는 모르는 단어나 구어체와 문어 체 간의 변환을 이해하는 데 도움을 받았고 내용적 측면에서는 주제문을 작성하고 논리적인 단락을 구성하는 데 도움을 받았다. 본 연구는 챗 GPT가 교수자와 학습자 간의 상호작용을 보완하여 학습자들의 학습 자 율성을 높일 수 있다는 가능성을 보여준다. 이는 전통적인 교수법의 한 계를 보완하며, 다양한 학습자들의 요구에 대응할 수 있는 새로운 교육 방법을 제시할 수 있다는 점에서 의의가 있다.

In this paper, we covered the basic design process of water-cooled cabinets and studied how to determine the target performance of heat exchanger design, which is essential in water-cooled cabinet design. A theoretical method was presented to set the target efficiency of the heat exchanger, and the pressure drop of air passing through the heat exchanger was predicted analytically. A cabinet-level thermal analysis was performed using the target efficiency and pressure drop data of the heat exchanger. The accuracy of the theoretical method was judged by comparing the theoretically predicted operating environment of the internal equipment with the analytically predicted operating environment of the internal equipment.