조선해양산업의 용접 자동화는 숙련 인력 부족과 고위험 환경 극복을 위해 협동로봇 중심으로 발전하고 있으나 선박블록 내 부 공간을 계측하기 위한 3차원 비전 센서의 경우 계측 거리에 따라 품질이 저하되는 문제가 있다. 본 연구는 협동로봇 용접 자동화를 위 해 3차원 포인트 클라우드 기반의 V-개선 용접선 검출 알고리즘을 제안하였으며 특히 자동화 용접에 필수적인 1m 미만 근거리에서 비전 센서 기술에 따른 계측 정밀도 및 검출된 평면의 개선각을 정량적으로 비교 검증하였다. 대중적으로 활용되고 있는 Active IR Stereo와 Time-of-Flight(ToF) LiDAR 센서를 400mm, 600mm, 800mm 거리에서 90° 개선각 시편으로 비교 평가한 결과 Active IR Stereo 센서는 삼각 측 량 원리의 한계로 인한 데이터 왜곡으로 상당한 각도 오차를 보였으며 800mm에서는 개선면 검출에 실패하였다. 반면 ToF LiDAR 센서는 데이터 왜곡에 강건하여 400mm에서 4.4°의 가장 낮은 평균 개선각 오차를 기록했으며 모든 거리에서 안정적으로 평면을 검출하였다. 이 를 통해 근거리 V-개선 형상 계측에는 ToF LiDAR 방식이 Active IR Stereo 방식보다 높은 정밀도를 제공하여 용접선 검출에 더 적합함을 정량적으로 검증하였다.

Modifying the softening point (SP) of pitch is crucial owing to its substantial influence on pitch applicability. This study presents a novel fluorination technique for engineering the SP of mesophase pitch (MP). Low-concentration fluorine gas was used to modify the edge sites of the MP, allowing for either an increase or decrease in the SP by controlling the gas reactivity. The fluorination was conducted with 20 vol% F2 gas under reaction temperature of 25, 50, and 75 ℃ for 2 h in atmospheric pressure. A reduction in SP was achieved through edge alkylation, with a decrease of up to 14.1% observed after the fluorination. Conversely, an increase in SP resulted from edge dealkylation at higher reaction temperatures. As the modified MPs retained perfect anisotropy, this study offers an effective strategy for adjusting the SP to meet application needs without causing structural deterioration.

본 연구의 목적은 PAPE에서 최적의 휴식 시간에 대한 급성 효과를 알아보기 위하여 VRT가 결합된 백 스쿼트 수행 후 휴식 시간에 따라 수직점프에 미치는 급성 효과를 비교하는 것이다. 본 연구의 대상자는 19세 이상의 성인 14명이 참가하였고(연령: 21.43 ± 1.81세, 신장: 175.39 ± 5.74 cm, 체중: 75.53 ± 7.61 kg), 가변저항을 결합한 부하 방법(고정부하 80%, 가변부하 20%)을 통해 백 스쿼트 전(pre) 과 백 스쿼트 후 휴식시간(R3, R6, R9)에 따라 수직점프의 높이와 하지 근전도의 자료를 구간에 따라 수 집하였다. 결론은 다음과 같다. 수직점프의 높이는 R3, R6에서 가장 높았다. 근전도에서 대퇴직근은 p2에 서 R9, 대퇴이두근은 p1에서 R9의 근활성도가 크게 나타났다. 전경골근은 p2에서 pre, R3, R9, p3에서 pre, p4에서 pre, R6, R9의 근활성도가 크게 나타났다. 비복근은 p1에서 R6, pre, R3 순으로, p2에서 R6 의 근활성도가 크게 나타났다. 이러한 결과를 통하여 PAPE 시 3-6분 정도의 적절한 휴식시간이 최대수행 능력과 근활성도의 효율적인 측면을 기대할 수 있다.

This study introduces a refined method for accurately determining the Invariant Point (IVP) of Very Long Baseline Interferometry (VLBI) antennas through constrained optimization, emphasizing the critical role of axis-offset sign conditions. Optical surveying techniques, commonly used to determine IVPs, inherently involve measurement limitations and observational errors, which may lead to biased estimations of the Azimuth (AZ) and Elevation (EL) axes. To mitigate these biases, we implement physical geometric constraints, including equal-radius conditions for target circles and equal inter-circle distances to ensure consistency across multiple Azimuth positions. Our method specifically incorporates a novel approach for determining the axis-offset sign, which significantly influences VLBI delay estimations. To validate the effectiveness of our method, we conducted numerical simulations using a virtual model with a predefined IVP and axis configuration. Realistic measurement noise was introduced to generate synthetic observational data. Simulation results clearly show that our constrained optimization approach substantially reduces bias and variance in IVP estimation compared to the geometric method proposed in our previous work. Specifically, the proposed method reduced the 3D RMSE of IVP estimation by approximately 40% (e.g., from 1.239 mm to 0.736 mm at 50 m observation distance) and the Interquartile Range (IQR) Error Norm by over 60% (e.g., from 0.949 mm to 0.343 mm at 50 m observation distance). The proposed method’s explicit handling of axis-offset sign conditions demonstrates originality and practical applicability, providing robust and reliable antenna reference point determination. Furthermore, we successfully applied this refined method to the Korean VLBI Network (KVN) Pyeongchang VLBI antenna, demonstrating practical effectiveness in operational geodetic VLBI environments. This advancement contributes to enhanced precision in International Terrestrial Reference Frame (ITRF) realization through improved VLBI station positioning.

In this study, we focus on the design and verification of a relatively low-cost point absorber wave energy converter, addressing the high costs and maintenance challenges of conventional wave energy generation systems. The proposed mechanical energy conversion device generates electricity by transforming the vertical motion of wave height into the vertical motion of a magnet connected to a spring. A simulation was conducted to analyze the magnet’s oscillation amplitude based on its weight and the spring constant. The performance of the device was then verified through simple water tank experiments. This study aims to develop a cost-effective wave energy generation system that can compete with wind and solar power generation.

본 연구의 목적은 고정저항과 가변저항을 적용한 백 스쿼트 시 단축성 구간을 전반부와 후반부 로 나누어 신체중심의 속도와 근전도 분석을 통하여 스티킹 포인트에 미치는 영향을 분석하는 것이다. 본 연구의 대상자로 19세 이상의 성인 15명이 연구에 참여하였다(연령: .25.8±2.6 yr, 신장: 181.4±2.2 cm, 체중: 79.7±3.9 kg). 2가지 부하 방법(고정부하, 고정부하+가변부하)를 통하여 백 스쿼트 시 3차원 동작분 석과 하지 근전도를 통하여 자료를 수집하였다. 이에 따른 결론은 다음과 같다. 신체중심의 속도는 VRT가 CRT보다 빠른 속도가 나타났고, 후반부가 전반부보다 빠른 속도가 나타났다. 근전도 분석에서 대퇴직근은 CRT가 VRT보다 근활성도가 크게 나타났고, 전경골근은 CRT의 전반부가 후반부보다 근활성도가 크게 나타났지만, VRT는 차이가 없었다. 이러한 결과를 통하여 고정부하의 약점을 가변부하를 통하여 효율적인 운동을 기대할 수 있다.

If the release point of the precision air delivery system is determined only by L/D, target accuracy can be greatly reduced due to changes in wind speed and direction by altitude. In this paper, after conducting a self-made precision air delivery system (PADS) drop test, we analyzed the problems that may occur due to wind changes by altitude and proposed an algorithm to determine the release point of PADS to increase the precision of PADS landing. As a result of conducting the simulation with this algorithm, it was similar to the results of the drop experiment. In addition, the conceptual design of HW and SW was carried out for the actual dropsonde implementation in the future.

This study sought various ways to prevent the occurrence of waste fishing gear and promote the recovery. It is expected that the problem of waste fishing gear can be effectively solved through measures such as strengthening education and publicity, technical measures, establishment of recovery infrastructure, and provision of incentives. In particular, introduction of the waste fishing gear recovery promotion point system gives fishermen practical motivation. It can be an important means of inducing leisure and sustainable fishing activities. In addition, by inducing the participation of private companies, it is expected to promote the recovery and recycling of waste fishing ports and contribute to the protection of the marine environment and fisheries resources. The government or local government should actively review the measures suggested in this study and prepare related laws and policies. In addition, it is necessary to establish a system to induce the participation of various stakeholders and support sustainable fishing activities through public-private cooperation. Through this, we will be able to achieve carbon neutrality goals in the fishing sector in response to climate change. This study suggests an early stage plan, and in future research, it is necessary to evaluate and find and improve practical effects through pilot projects. Moreover, it is necessary to study the management of closed fishing gear and carbon neutrality practice measures at the global level by seeking international cooperation measures. Consequently, more effective and sustainable marine environment and fishery resource protection measures can be prepared.

In modern society, buildings are becoming more complex, and the population is becoming more densely populated. Such large buildings require a variety of evacuation measures, as there is a high possibility of large-scale human casualties due to increased evacuation distance and evacuation time in the event of a fire. Strobe light and exit sign light are used as important evacuation equipment to provide early warning and evacuation directions. In this thesis, we conducted a fire simulation assuming that a fire occurrence point notification function and a strobe light function were added to equipment such as visual alarms and evacuation guidance, and compared and analyzed the difference in evacuation completion time with existing equipment. The scenarios for the simulation were divided into “general fire situations” and “fire location and evacuation exit guidance situation” and the differences in evacuation completion time in the event of a fire were compared and analyzed for each floor from the 1st floor to the 3rd floor. The maximum travel distance to complete evacuation in the case of a fire on the first floor decreased by 80.6 m and the evacuation completion time decreased by 329.4 seconds, and the maximum travel distance to complete evacuation in the case of a second-floor fire decreased by 28.5 m and the evacuation completion time by 438.8 seconds. During the fire on the third floor, the maximum distance decreased until evacuation was completed to 3.4 m, and the evacuation completion time was reduced by 355.6 seconds. It is expected that if the congestion level of evacuation routes is reduced by utilizing the congestion level of evacuation exits when fire alarm systems and evacuation equipment are activated, the evacuation completion time will be further shortened and evacuations will be carried out quickly and safely.

이동 물체의 전역 경로 탐색에 있어 출발지점과 도착지점은 반드시 필요한 조건 중 하나이다. 선박의 경로 탐색에 있어 도착 가능 지점은 부두 이외 선박의 입출항 전 대기 장소 및 선박 수리 등 다양한 목적으로 이용되는 정박지(Anchorage)도 포함될 수 있다. 이 러한 정박지는 연안 해역 환경에 따라 특정 형태로 설계된 공간으로 경로 탐색을 위한 도착지점은 선박이 정박을 위한 투묘 지점이라고 볼 수 있다. 이에, 본 연구에서는 샘플링 기반 탐색 알고리즘 중 PRM 및 계산 기하학 알고리즘을 통해 정박지라는 특정 공간에 대해 다른 선박이 점유하지 않는 공간 탐색을 통한 투묘 지점 산출 방법을 제시하였다. 또한, 개발된 알고리즘을 검증하기 위하여 국내 목포항 11번 정박지를 대상 해역으로 선정하고 시뮬레이션을 수행한 결과 다른 선박이 점유하지 않는 공간에 대해 투묘 지점을 탐색할 수 있었다. 본 연구의 결과는 향후 선박의 의사 결정 및 VTS의 정박지 관리를 위한 지원 방안으로 활용될 수 있을 것으로 기대된다.