국제해운의 탈탄소 전환과 IMO GHG 전략에 따른 규제 강화로 선박별 정밀 배출 산정이 요구되고 있다. 그러나 실제 운항 선 박의 주기관 출력 정보는 외부 데이터베이스에 의존하는 경우가 많아 데이터 수집 단계에서 상당한 경제적 비용과 시간 지연이 발생한 다. 이러한 제약을 완화하기 위해, 본 연구는 AIS 정적 정보 중 선체길이를 단일 입력변수로 활용하여 선종별 주기관 출력을 기계학습으 로 추정하는 방법을 제안한다. 본 연구에서는 선형회귀, K-최근접이웃, 랜덤포레스트, 그래디언트부스팅, AdaBoost, XGBoost, LightGBM, CatBoost 등 8종의 기계학습 모델을 적용하였다. 수집한 데이터는 선종별로 분리한 뒤 무작위 분할하였고, 90% 학습셋에서 10-fold 교차검 증을 수행한 후 10% 홀드아웃 테스트로 최종 성능을 평가하였다. 테스트셋 기준 화물선은 CatBoost가 R²=0.96, 탱커선은 Gradient Boosting이 R²=0.96으로 가장 우수하였다. 여객선은 XGBoost가 R²=0.89, 예인선은 CatBoost가 R²=0.76을 보였다. 본 연구를 통해 AIS 데이터를 이용하여 주기관 출력을 추정할 수 있음을 확인하였다.

Five novel miniature bipolar radiofrequency (RF) electrode tips with distinct tip geometries (spherical, flat, square, and 45° angled) were developed to enable high-precision tissue ablation. Performance was evaluated on saline-soaked tissue, ex vivo bovine liver, and porcine muscle under consistent RF power settings. All designs produced highly localized lesions only a few millimeters across, confirming precise ablation with minimal damage to surrounding tissue. Tip geometry influenced ablation efficiency: a 45° angled tip created ~5 mm lesions at lower power (highest efficiency), whereas an ultra-fine 1.0 mm tip produced ~1 mm lesions but required higher power. These results indicate that the new bipolar RF electrodes achieve precise, localized tissue ablation with minimal surrounding tissue damage and show promise for precise lesion removal in minimally invasive surgery.

온실가스 배출을 줄이기 위해 기존 선박에 사용되는 내연기관을 대체할 수 있는 다양한 기술이 제안되고 있으며, 그중에서도 고 효율·무배출 특성을 가진 연료전지가 유망한 대안으로 주목받고 있다. 본 연구에서는 선박의 종류 및 규모에 따라 네 가지 유형의 선박을 선정하고, 기존 내연기관 기반 추진 시스템을 연료전지-배터리 하이브리드 추진 시스템으로 전환하는 방안을 검토하였다. 제안된 하이브리 드 추진 시스템은 주 전원으로 고분자전해질막연료전지(PEMFC), 보조 전원으로 Battery를 사용한다. PEMFC가 기본 부하(base load)를 담당하 고, Battery는 피크 부하(peak load)를 담당한다. PEMFC는 50kW 스택을 기본 단위로 모듈화하여 적용하였으며, 시스템 전체 크기, 연료전지와 배터리의 비율, 주변 기기와의 연계 등을 고려하여 각 선박 유형에 적합한 시스템 구성을 도출하였다. 연구 결과, 선박의 종류와 운항 특성 에 따라 PEMFC-Battery hybrid propulsion system의 구성이 달라져야 함을 확인하였다. 항해가 길어질수록 PEMFC의 비중을 높이는 것이 필요 하며 액화수소의 사용이 강제화된다. 또한 항해 구역과 긴급 상황에 대응할 수 있도록 시스템의 단일/이중화 여부 또한 고려되어야 한다. 선 박 규모에 따라 적정한 추진 전동기와 주변 기기 설치를 고려해야 한다. 이러한 운항 조건과 설계 요소를 반영한 PEMFC-Battery hybrid propulsion system은 다가오는 배출 규제를 충족할 수 있으며, 해양 분야 탈탄소화를 위한 실현 가능한 대안이 될 수 있다.

Fault detection in electromechanical systems plays a significant role in product quality and manufacturing efficiency during the transition to smart manufacturing. Because collecting a sufficient number of datasets under faulty conditions of the system is challenging in practical industrial sites, unsupervised fault detection methods are mainly used. Although fault datasets accumulate during machine operation, it is not straightforward to utilize the information it contains for fault detection after the deep learning model has been trained in an unsupervised manner. However, the information in fault datasets is expected to significantly contribute to fault detection. In this regard, this study aims to validate the effectiveness of the transition from unsupervised to supervised learning as fault datasets gradually accumulate through continuous machine operation. We also focus on experimentally analyzing how changes in the learning paradigm of the deep learning model and the output representation affect fault detection performance. The results demonstrate that, with a small number of fault datasets, a supervised model with continuous outputs as a regression problem showed better fault detection performance than the original model with one-hot encoded outputs (as a classification problem).

Conventional bipolar electrodes (typically with round or flat tips) deliver radiofrequency energy in a broad, continuous manner. Their larger tip size and simple shape cause the applied energy to disperse over a wide area, making precise lesion control difficult and often leading to collateral tissue damage. As a result of these design limitations, traditional electrodes exhibit lower energy efficiency and tend to create lesions that unintentionally extend beyond the target area, with excessive thermal spread to surrounding tissues. In contrast, the five newly developed bipolar electrode designs concentrate energy delivery more effectively and provide improved control over lesion size and shape. These novel electrodes demonstrated higher energy efficiency, produced well-confined lesions, and minimized thermal injury to adjacent tissues, thereby overcoming the major drawbacks of conventional designs.

본 논문에서는 다양한 FDM 출력 공정 변수에 따라 결정되는 출력물의 비등방 물성을 구조 해석 과정에서 반영할 수 있는 개선된 해석 방안을 제안하였다. 출력 공정 변수에 대한 물성의 민감도를 분석하였으며, 실제 출력물에 대한 인장 시험을 통해 적층 방향에 따라 이방 특성이 도출됨을 확인하였다. 또한, 출력물에 대한 단면 분석을 통해 적층 레이어 높이 및 필라멘트 채움률 등의 공정 변수 들이 내부 공극 특성에 영향을 미치며, 결과적으로 출력물의 이방 특성이 유발된다는 사실을 확인하였다. 나아가, 적층 방향, 적층 레 이어 높이, 필라멘트 채움률 등이 동시에 고려된 균질화 모델 분석을 통해 출력 과정에서 발생되는 내부 공극 분포가 출력물의 기계적 거동 특성에 미치는 영향을 규명하고자 하였다. 수치 예제로써 로어 컨트롤 암 출력물의 비등방 특성이 반영된 구조 해석을 수행하였 으며, 이를 통해 FDM 출력물 설계 과정에서의 개선된 해석 방안의 타당성을 검증하였다.

In this paper, This study examines the acquisition patterns of Chinese advanced Korean learners before and after comprehensive output is applied in the acquisition of adnominal suffix, The aim of this study is like to verify whether it functions as a “'perceptive”'among the important roles in second-language acquisition. The main research question sad dressed are as follows: 1. What is the acquisition pattern of '-(으)ㄴ' and '-던' be fore and after applying the compressible output? 2. What is the cognitive processing patterns of '-(으)ㄴ' and '-던' of learners before and after the compressible output is applied? 3. (Hypothesis verification)The compressible output functions to recognize the target grammar item. Pre- and post-SPRT and WGJT are conducted to solve Research Problems 1 and 2, and to solve Research Problem 3, interview contents with participants and reconstructed contents are analyzed. The results in dicate that for the first research question, the response rate of learners to the tubular ending '-(으)ㄴ' question increased the post-correct answer rate, and resulted in more effective acquisition compared with before the output is applied. Meanwhile, the learner's response rate to “'-던”'improved slightly. However, ]no significant difference is indicated between the before and after cases;,therefore, one may not conclude that the acquisition of '-던' after the output is more effective. Regarding the cognitive processing patterns '-(으)ㄴ' and '-던', the main effect of the '-(으)ㄴ' sub-item type(F=3.14, P= .045) and the main effect before and after the output is applied(F=28.54, P= .000) are significant. However, the item type and the interaction before and after the output is applied(F=0.39, P= .75) cannot be confirmed as significant. In other words, both the pre- and post-learners ex hi bit different sensitivities depending on the type of question. However, one may not firmly conclude that the pattern of varying sensitivities differs before and after the output is applied. Regarding the question pertaining to '-던' one may not conclude that the main effect of the item type(F=1.11, P= .37), the main effect before and after the output is applied(F=1.65, P=.37), and the interaction between the item type and the pre-and post-output(F=1.71, P= .14) are all significant. In other words, one may not conclude the sensitivity of '-던' varies bypre-/ post-output and the item type. Interviews and reconstructions with participants are analyzed to verify the "getting to know" hypothesis among the important roles posed in the third research question. The result shows that,, in acquiring a second language, the understandable output clearly recognizes the gap between what one wishes to express and what one can use accurately through communication, corrects errors from the other person’'s feedback, or activates the knowledge one learned to promote the level of accurate use from avoidance for the part one wishes to express when correcting errors.

This study was conducted through experiments by producing an image output evacuation guide light linked with a smoke detector. To summarize the results, first, the biggest recognition distance of the door at 30% smoke concentration was found to be the image output evacuation guide light. This is because of visual impairment and fear caused by indoor smoke, and in the process of finding the light of the emergency exit, accurate recognition of the evacuation behavior was searched even at the farthest distance, and it is judged that the time required for evacuation was short. Second, the biggest recognition distance of the door at 70% smoke concentration was the image output evacuation guide light, which showed the longest recognition distance. It is judged that even in smoke with many evacuees, the door is accurately recognized while seeing the light of the image output evacuation guide light and exits safely. Third, when the smoke concentration was 100%, the smoke rose and the evacuation guide light at the top of the door was not identified as thick smoke, and the image output evacuation guide light was displayed on the bottom of the passage, indicating that the evacuee accurately recognized the door and escaped safely to the outside even from a long distance.

In this study, contribution evaluation method applying Independent Component Analysis (ICA) was proposed. The necessity of applying ICA to the contribution evaluation was investigated through numerical simulation. The simulation modeled a scenario where the vibration/noise sources were physically overlapped in a small space, and their frequency characteristics were similar. For comparison between the conventional contribution evaluation method and the proposed method, the contribution evaluation was performed using the ordinary and partial contribution evaluation methods. Through this analysis, it was confirmed that the proposed method can identify contributions by restoring the signal when the frequency characteristics of the vibration/noise sources were similar, and their positions overlapped. These results confirm that the contribution evaluation method based on independent component analysis is effective in appropriately analyzing vibration/noise sources when their frequency characteristics are similar, and their positions overlap.

In this paper, we address the issue of temperature uniformity in high-power antenna systems by proposing and analyzing various design strategies. Specifically, when there is significant spatial freedom in the internal coolant pathways of the cooling plate, a counterflow approach is implemented to achieve temperature uniformity. Conversely, in scenarios where spatial constraints exist, a differential fin area design is proposed to effectively manage heat distribution. Additionally, in cases where the design of coolant pathways is restricted and fin design is not feasible, we suggest minimizing temperature variations by adjusting the thermal conductivity of the carriers located beneath the heat-generating components. This comprehensive approach aims to enhance the thermal management of high-power antenna systems, ensuring improved system stability and performance.

In this study, power generation characteristics based on water flow dynamics in a pipe system with a mobile firefighting robot were analyzed using 3D CAD modeling and computational fluid dynamics(CFD) simulations. The water flow field which is significantly affected by applied pressure, generates mechanical torque at the turbine blades, enabling power generation. The inlet pressure of the flow field was set to approximately 6 to 12 bar, and the flow characteristics such as velocity, pressure, and mass flow rate, along with power generation characteristics, were analyzed under various turbine rotational velocities. It was observed that higher inlet pressures resulted in increased torque and mechanical power output at the turbine blades. This research is expected to serve as a fundamental design and data reference to improve the performance of firefighting robots at fire sites.

본 논문에서는 3D 프린팅 공정을 통해 제작된 단섬유 강화 복합소재 구조물의 기계적 거동을 효과적으로 예측하기 위한 AM 공정 연계 구조 해석 기법을 제안하였다. 복합소재 3D 프린터(Mark Two, Markforged)를 활용하여 다양한 노즐 경로를 갖는 인장 시편을 출력하였으며, 출력물에 대한 인장 시험을 진행하였다. 또한, 노즐 경로에 따른 부위별 이방 물성을 도출하기 위해 실험적 데이터를 기반으로 역공학 기법을 적용하였다. 제안된 AM 공정 연계 구조 해석 방안의 타당성을 검증하기 위해 실험 결과와의 비교/분석을 병 행하였으며, 부위별 이방 물성이 반영된 FE 모델을 바탕으로 AM 공정 연계 구조 해석을 수행함으로써 복합소재 3D 프린팅 출력물의 거동 양상을 정확하게 예측할 수 있음을 확인하였다.

In this paper, we aim to improve the output quality of a food 3D printer through optimized component design and implementation. Existing 3D printers produce customized outputs according to consumer needs, but have problems with output speed and poor quality. In this paper, we aim to solve this problem through optimized design of unit parts such as the extruder, nozzle, guide, and external case. Fusion 360 was used for element design, and in the performance evaluation of the implemented system, the average precision was 0.06mm, which is higher than the non-repeatable precision of ±0.1㎜ of other products, and the feed speed of the existing system was evaluated to be more than twice as fast, from 70mm/s to 140mm/s. In the future, we plan to continuously research output elements that can produce texture and color and device control methods for convenience.

The laser power has been continually increased since the laser was developed in the mid-20th century. Achieving higher laser power requires not only enhancing the cooling performance of laser systems but also addressing the potential degradation of optical characteristics due to thermal deformation induced by laser beam absorption in a mirror. This study delves into the thermal deformation characteristics of mirrors in high-power laser systems. To minimize thermal deformation by heat absorption, Zerodur, known for its low coefficient of thermal expansion, was employed as the mirror material. Various configurations including circular, rectangular, and spline shapes were implemented on a solid mirror structure. Furthermore, two different diameter of a mirror, 300mm and 400mm, were considered to investigate the size effect of the high-power laser beams. Also, three different transmitted beam power were adopted: 50W, 250W, and 500W. Based on the finite element analysis for the thermal deformation, the deformation characteristics of the different types of mirror structures were investigated and analyzed for high-power laser systems.

3D 프린팅 콘크리트는 임의의 형상을 자유롭게 적층하여 제작할 수 있다는 장점을 가지고 있지만, 노즐의 구조 및 형상에 따라 곡선부의 출력 품질이 달라진다. 또한, 공기중에서 출력한 경우와 수중에 서 출력한 경우 그 품질이 달라진다. 본 연구에서는 고정 마감날을 가진 사각형 노즐을 이용하여 3D 프린팅 모르타르를 수중에서 곡선 형태로 출력하고 적층한 후 출력성능, 적층성능, 및 역학적성능을 평가하였다. 30 × 30 mm 사각형 개구부를 가지고 있고 노즐 끝 양 측면에 고정 마감날이 설치된 노 즐을 사용하였다. 사전 직선 출력시험에서 선정된 조건인 호퍼 회전속도 14 rpm, 노즐 이동 속도 2000 mm/min을 적용하여 출력하였고, 1층 높이를 30mm로 출력하여 5층 적층하였다. 출력 및 적층 결과, 직선부분의 표면은 양호한 반면 곡면부분, 특히 곡률이 큰 곡선부분의 바깥쪽에서 표면균열이 관찰되었다. 직선부분의 치수 일관성은 양호한 반면, 곡률 반경이 작은 곡선부분의 폭 차이가 나타났 다. 곡선부분의 밀도와 압축강도는 직선부분보다 낮았다. 이는 곡선부에서 직사각형 노즐 회전에 따른 재료 토출이 불균일하기 때문인데, 이러한 문제점을 보완할 수 있는 제어 기술 개발이 필요하다.

In this study, the various process conditions for high-power DC Magnetron Sputtering (DCMS) on the surface roughness of carbon thin films were investigated. The optimal conditions for Si/C coating were 40min for deposition time, which does not deviate from normal plasma, to obtain the maximum deposition rate, and the conditions for the best surface roughness were – 16volt bias voltage and 400watt DC power with 1.3x10-3torr chamber pressure. Under these optimal conditions, an excellent carbon thin film with a surface roughness of 1.62nm and a thickness of 724nm was obtained. As a result of XPS analysis, it was confirmed that the GLC structure ( bonding) was more dominant than the DLC structure ( bonding) in the thin film structure of the carbon composite layer formed by DC sputtering. Except in infrequent cases of relatively plasma instability, the lower bias voltage and applied power induces smaller surface roughness value due to the cooling effect and particle densification. For the optimal conditions for Graphite/C composite layer coating, a roughness of 36.3 nm and a thickness of 711 nm was obtained under the same conditions of the optimal process conditions for Si/C coating. This layer showed a immensely low roughness value compared to the roughness of bare graphite of 242 nm which verifies that carbon coating using DC sputtering is highly effective in modifying the surface of graphite molds for glass forming.

Titanium constitutes approximately 60% of the weight of steel and exhibits strength comparable to steel's but with a higher strength-to-weight ratio. Titanium alloys possess excellent corrosion resistance due to a thin oxide layer at room temperature; however, their reactivity increases above 600°C, leading to oxidation and nitridation. Welding titanium alloys presents challenges such as porosity issues. Laser welding minimizes the heat-affected zone (HAZ) by emitting high output in a localized area for a short duration. This process forms a narrow and deep HAZ, reducing the deterioration of mechanical properties and decreasing the contact area with oxygen. In this study, fiber laser welding was conducted on 8.0mm thick Ti-6Al-4V alloy using the Bead On Plate (BOP) technique. A total of 25 welding conditions were experimented with to observe bead shapes. The results demonstrated successful penetration within the 0.792mm to 8.000mm range. It was concluded that this experimental approach can predict diverse welding conditions for Ti-6Al-4V alloys of various thicknesses.