• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.35 no.4
• /
• pp.215-226
• /
• 2022

Significant efforts have been devoted to developing high-performance composite materials by emulating the structure of biological creatures with superior mechanical characteristics. Nacre has been one of the most sought-after natural structures due to its exceptional fracture toughness compared with the constituent materials. However, the effect of manipulating the nacre-like geometry on the impact performance has not been fully investigated thus far. In this study, composites of randomly manipulated nacreous geometry are numerically developed and the impact performance is analyzed. We develop an algorithm by which the planar area of platelets in the nacre-like design is randomly resized. Thereafter, the numerical models of nonuniform nacre-patterned multi-layer structures are developed and the drop-weight impact simulation is performed. The impact behaviors of the model are evaluated by using the ratio of absorbed energy, the von Mises stress distribution, and the impact force-time curve. Therefore, the effect of the geometric irregularity on the nacre-patterned design is elucidated. This insight can be efficiently utilized in establishing the optimum design of the nacre-patterned structure.

• Journal of the Korea Society of Computer and Information
• /
• v.27 no.11
• /
• pp.181-190
• /
• 2022

In this paper, we use a LiDAR sensor and an image camera to detect a left-turning waiting vehicle in two ways, unlike the existing image-type or loop-type left-turn detection system, and a left-turn traffic signal corresponding to the waiting length of the left-turning lane. A system that can efficiently assign a system is introduced. For the LiDAR signal transmitted and received by the LiDAR sensor, the left-turn waiting vehicle is detected in real time, and the image by the video camera is analyzed in real time or at regular intervals, thereby reducing unnecessary computational processing and enabling real-time sensitive processing. As a result of performing a performance test for 5 hours every day for one week with an intersection simulation using an actual signal processor, a detection rate of 99.9%, which was improved by 3% to 5% compared to the existing method, was recorded. The advantage is that 99.9% of vehicles waiting to turn left are detected by the LiDAR sensor, and even if an intentional omission of detection occurs, an immediate response is possible through self-correction using the video, so the excessive waiting time of vehicles waiting to turn left is controlled by all lanes in the intersection. was able to guide the flow of traffic smoothly. In addition, when applied to an intersection in the outskirts of which left-turning vehicles are rare, service reliability and efficiency can be improved by reducing unnecessary signal costs.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.27 no.7
• /
• pp.1098-1105
• /
• 2021

The International Maritime Organization has steadily strengthened environmental regulations on nitrogen oxides and carbon dioxide emitted from marine vessels. Consequently, the demand for electric propulsion vessels based on eco-friendly elements has increased. To this end, research and development has been steadily conducted for various vessels. In electric propulsion systems, a redundancy configuration is typically adopted to increase reliability and facilitate the onboard arrangement. Furthermore, studies have been actively conducted to ensure the safety of electric propulsion systems through the combination with digital twin technology. A digital twin can be used to predict outcomes in advance by implementing real-world equipment or space in a virtual world like twins, integrating real-world information and data with the virtual world, and performing computer simulations of situations that can occur in a real environment. In this study, we perform failure modes and effects analysis (FMEA) to validate the electric power management system (PMS) redundancy scheme for the digital twin technology development of electric propulsion vessels. Then, we propose the role and algorithm of PMS as a compensation function for preventing primary and secondary damages caused by a single equipment failure of the PMS and preventing additional damages by analyzing the impact on the entire system under real vessel operating conditions based on the redundancy FMEA suggested for the ship classification and certification. We verified the improvement in propulsion conservation through tests.

• Journal of the Society of Disaster Information
• /
• v.19 no.1
• /
• pp.161-172
• /
• 2023

Safety education delivered to construction workers in a lecture manner has limitations in concentration and immersion, so delivery power and interest are low. In order to improve unstable behavior through education and prevent safety accidents, it is necessary to change the paradigm to hands-on education. Purpose: Experiential safety education aims to contribute to preventing accidents for construction workers by quickly recognizing risks, improving emergency response skills, and verifying the effectiveness of pre- and post-learning. Method: Based on a survey of workers who experienced the same work environment as the actual construction site, an opinion survey on the pre- and post-safety experience education and a variable measurement tool were planned, and a research hypothesis was established. Results: The Bayesian theory and MC simulation analysis were used to analyze the structural equation model, and the change in construction worker behavior was confirmed through the intended safety (A), non-experiential education in the sub-area of anxiety (B), average, standard deviation, and minimum and maximum values. Conclusion: The effect of education and industrial accidents are reduced only when construction workers are motivated to participate.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.21 no.6
• /
• pp.241-249
• /
• 2022

This paper discusses the design of a ground clutter prevention fence for a radar wind profiler (RWP). The design point of the clutter fence is to improve the quality of the received signal by removing the non-weather clutter coming from the side. In this paper, a clutter prevention fence composed of a metallash mesh around the RWP is proposed, and the phase center of the antenna, the length, and height of the down fence, and the height and slop of the top fence through M&S are designed. The designed ground clutter prevention fence and 256 active phase array antennas were used as basic data. The effectiveness of the design was confirmed by a simulation. The side lobe in the ±90° direction was reduced by more than 30dB depending on the presence or absence of the designed ground clutter prevention fence. The fence was manufactured by 3D modeling, and the clutter shielding performance of approximately 20dB or more on the side of the antenna (±90°) was confirmed by applying it to the currently operated RWP.

• Journal of Korea Society of Industrial Information Systems
• /
• v.14 no.3
• /
• pp.15-21
• /
• 2009

In this paper, we proposed an iterative digital image watermarking technique using encrypted binary phase computer generated hologram in the discrete cosine transform(OCT) domain. For the embedding process of watermark, using simulated annealing algorithm, we would generate a binary phase computer generated hologram(BPCGH) which can reconstruct hidden image perfectly instead of hidden image and repeat the hologram and encrypt it through the XOR operation with key image that is ramdomly generated binary phase components. We multiply the encrypted watermark by the weight function and embed it into the DC coefficients in the DCT domain of host image and an inverse DCT is performed. For the extracting process of watermark, we compare the DC coefficients of watermarked image and original host image in the DCT domain and dividing it by the weight function and decrypt it using XOR operation with key image. And we recover the hidden image by inverse Fourier transforming the decrypted watermark. Finally, we compute the correlation between the original hidden image and recovered hidden image to determine if a watermark exits in the host image. The proposed watermarking technique use the hologram information of hidden image which consist of binary values and encryption technique so it is very secure and robust to the external attacks such as compression, noises and cropping. We confirmed the advantages of the proposed watermarking technique through the computer simulations.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.23 no.4
• /
• pp.189-196
• /
• 2023

As the manufacturing paradigm shifts, various collaborative robots are creating new markets. Demand for collaborative robots is increasing in all industries for the purpose of easy operation, productivity improvement, and replacement of manpower who do simple tasks compared to existing industrial robots. However, accidents frequently occur during work caused by collaborative robots in industrial sites, threatening the safety of workers. In order to construct an industrial site through robots in a human-centered environment, the safety of workers must be guaranteed, and there is a need to develop a collaborative robot guard system that provides reliable communication without the possibility of dispatch. It is necessary to double prevent accidents that occur within the working radius of cobots and reduce the risk of safety accidents through sensors and computer vision. We build a system based on OPC UA, an international protocol for communication with various industrial equipment, and propose a collaborative robot guard system through image analysis using ultrasonic sensors and CNN (Convolution Neural Network). The proposed system evaluates the possibility of robot control in an unsafe situation for a worker.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2022.05a
• /
• pp.506-506
• /
• 2022

비점오염원에서 배출되는 오염부하량(BOD, T-P)은 점오염원의 2배 이상을 차지하고 있어 비점오염원 관리에 대한 관심이 증대되고 있다. 이에 비점오염원의 효율적 관리를 위한 전략 및 추진과제 마련을 위해 제1차('04-'11), 제2차('12-'20) 비점오염원 관리 종합대책(이하 종합대책)이 수립 및 이행되었다. 이어 2016년 물환경보전법 개정에 따라 종합대책의 수립이 법제화되고 지난 2020년 말 제3차 비점종합대책('21~'25)이 수립되었다. 제3차 비점종합대책은 수질개선이 체감되는 비점오염원 관리라는 비전을 가지며 도시, 농·축산, 산림, 관리기반의 4개 분야에 총 71개의 세부 추진과제를 제시하고 있다. T-P 비점오염배출부하량 5% 감축, 불투수율 감축, 비점오염관리지역개소 확대, 고랭지 흙탕물 관리지역 구역 확장, 지역 거버넌스 구축을 대책의 목표와 각 분야별 관리지표로 제시하고 있다. 물환경보전법 제53조의5와 동법 시행령 제75조의3에 따라 환경부장관은 매년 이행사항을 점검 및 평가하여 그 결과를 비점오염원 관리 정책의 수립 및 집행에 반영해야 한다. 지난 제1·2차 대책의 경우 성과 점검 및 관리를 위한 체계가 부재하여 사업의 실효성 확보에 한계가 있었으며 이에 따라 소관별 이행사항 점검 및 평가체계의 필요성이 제기되었다. 따라서 본 연구에서는 종합대책 이행평가 전략 및 세부 추진체계를 마련하여 효율적인 소관별 이행사항 점검 및 평가를 도모하고자 하였다. 분야별 세부 추진과제는 매년, 대책의 목표와 각 분야별 관리지표는 대책 시행 후 5차년에 점검 및 평가할 수 있도록 구성하였다. 또한 종합대책의 최종 목표 달성 시뮬레이션을 통해 5차년 이후 원활한 평가가 이루어질 수 있도록 하였다. 본 연구에서 마련한 이행평가 체계를 통해 적절한 이행평가 및 효율적인 비점오염원 관리를 도모할 수 있을 것으로 사료된다.

• Journal of Navigation and Port Research
• /
• v.46 no.1
• /
• pp.42-56
• /
• 2022

Due to the 4th Industrial Revolution announced at the Davos Forum, the World Economic Forum, in 2016, industrial trends around the world are changing rapidly and intelligently. Among them, the digital twin is drawing attention from all industries as a groundbreaking technology that reduces unnecessary costs and trial and error by implementing real objects, systems, and environments in the same way in the real virtual world and using them to perform simulation analysis. In particular, there is a lot of interest in the application of digital twin technology in solving ports safety and efficiency challenges at once. However, there is a lack of in-depth research for the application of digital twin technology in the port, and in particular, there is a lack of research on measurable data for the implementation of the digital twin in ports. The purpose of this study was to increase granularity and connectivity through measurable data investigation for the application of digital twin technology at container ports. Based on the study results, data factors for container port application were classified into crane data, operational data, physical data, and transportation data, and factor composition, correlation with factors, and fitness were confirmed through confirmatory factor analysis.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.23 no.3
• /
• pp.119-125
• /
• 2023

IT infrastructure operation has advanced, and the methods for managing systems have become widely adopted. Recently, research has focused on improving system management using Syslog. However, utilizing log data collected through these methods presents challenges, as logs are extracted in various formats that require expert analysis. This paper proposes a system that utilizes edge computing to distribute the collection of Syslog data and preprocesses duplicate data before storing it in a central database. Additionally, the system constructs a data dictionary to classify and count data in real-time, with restrictions on transmitting registered data to the central database. This approach ensures the maintenance of predefined patterns in the data dictionary, controls duplicate data and temporal duplicates, and enables the storage of refined data in the central database, thereby securing fundamental data for big data analysis. The proposed algorithms and procedures are demonstrated through simulations and examples. Real syslog data, including extracted examples, is used to accurately extract necessary information from log data and verify the successful execution of the classification and storage processes. This system can serve as an efficient solution for collecting and managing log data in edge environments, offering potential benefits in terms of technology diffusion.