• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.25 no.5
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• pp.321-328
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• 2016

Cranes are generally used to drop or lift equipment or materials. The present study focuses on equipment used for dropping and lifting the sonar system for undersea exploration. This study deals with a GA-based MATLAB$^{(R)}$ simulation for the design optimization of a new overboarding prototype with a two degree-of-freedom mechanism, including a parallelogram link, which is efficient in sonar system operation and maintenance. First, the strengths and weaknesses of the existing overboarding mechanisms are analyzed. The new mechanism to solve these problems is then suggested. For the proposed mechanism, the GA-based MATLAB$^{(R)}$ simulation technique is applied to the proposed mechanism to optimize the link lengths and the actuator lengths. By doing this, the mechanism cannot interfere in the hull's internal environment. Hence, the work range of motion (ROM) is satisfied, and good torque-angle properties are obtaind. The developed technology will be helpful in calculating the maximized output torque of the actuator for the application in practice using a similar type of the proposed mechanism.

• 보존과학연구
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• s.16
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• pp.41-58
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• 1995

Several comparisons of treatment methods for stabilizing corroded Chinese coins at Shin-an marine sites were investigated. In aqueous solution, the seexamination were performed to show whether chloride ions are gradually removed, patination changes are acceptable and archaeological details are identified. The six desalting methods showed that the orders of removal of chloride ions were ranked electrolysis (electolyte : 0.1M sodium sesqui.)> 5% sodium dithionite(1M NaOH)> 5%sodium dithionite(0.1M sesqui.)> 5% citric acid> 0.1M sodium sesquicarbonate>deionized water. As the examinations of moisture absorption to the relative humidity has compared for bronze disease, all of desalted coins for the R.H 53% and R.H 75%except to R.H 95% are showed serious bronze disease.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.4
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• pp.1154-1163
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• 1996

This paper presents a three dimensional modeling and dynamic anlaysis of a hydraulic excavator. An excavator is composed of a ground, an under-frame, two idlers, two spockets, an upper-frame, a boom, an arm, a bucket two yokes, two connecting rods, two boom cylinders, an arm cylinder, and a bucket cylinder. Each cylinder is modeled with two separate bodies which are linked to each other by a translational joint. The three dimensioanl model of the excavator consists of 22 bodies and each body is assumed as rigid. This paper suggested the maximum lifting capability, a critical load and reaction forces at joints form the DADS simulation. It was presumed that the reaction forces due to a critical load are three times bigger than those due to the maximum lifting capacity.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.11
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• pp.4738-4744
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• 2011

This study proposes the system of new small sluice gate operated without the upper concrete structure. The new mechanism is composed of hydraulic system, driving mechanism to feed the floodgate up and down, hydrological locking device, safety device and etc. The hydraulic pumps and control systems away from the location of the sluice gate systems are installed and controled in place. The feed device with the hydraulic rack, pinion and hydraulic actuator is installed on the side of the sluice gate. The following results take the advantages of cost reduction, operation safety and compact product.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.4
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• pp.31-38
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• 2021

In this paper, we proposed an optimal design for determining the shape of a lifting lug freely by applying a multivariate function to the D-type lug, which is commonly used in shipyards. We derived the optimal aspect ratio of the lug through structural analysis and analyzed the safety and behavior of the lug aspect ratio. As a result, two types of final candidates, both lighter than the existing lug weight, were suitable for the ratio. They were found to have the greatest force at an angle of 45 degrees when a load of 100 tons was imposed. When the horizontal and vertical feature ratio of the lug was 1:3, it showed excellent results in terms of safety rates while maintaining weight reduction and functional aspects.

• Journal of the Korea Institute of Building Construction
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• v.20 no.6
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• pp.497-504
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• 2020

In Korea construction industry, researches are being conducted to reduce the disasters related tower crane due to the increase of tower crane's usage and accidents continuously. Although the usage amount of remote control tower crane has been increasing recently, the research on remote-control tower crane is insufficient. In this study, the importance ranking of remote control tower crane's accident factors derived by AHP analysis. AHP questionnaire was conducted to engineers (or operators) like construction site engineer, construction manager, safety engineer, and tower crane operator, who have more than 10 years career. The results of AHP analysis reveal that top ranking factor of remote control tower crane's accident is lifting work for materials. Therefore, the high importance factors should be managed, and taken the priority measures for reducing the tower crane accidents by using the results of this research.

• Journal of Drive and Control
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• v.19 no.4
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• pp.62-69
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• 2022

Construction machinery is exposed to accidents such as collisions, narrowness, and overturns during operation. In particular, mobile crane is operated only with the driver's vision and limited information of the assistant worker. Thus, there is a high risk of an accident. Recently, some collision avoidance device using sensors such as cameras and LiDAR have been applied. However, they are still insufficient to prevent collisions in the omnidirectional 3D space. In this study, a rotating LiDAR device was developed and applied to a 250-ton crane to obtain a full-space point cloud. An algorithm that could provide distance information and safety status to the driver was developed. Also, deep-learning segmentation algorithm was used to classify human-worker. The developed device could recognize obstacles within 100m of a 360-degree range. In the experiment, a safety distance was calculated with an error of 10.3cm at 30m to give the operator an accurate distance and collision alarm.

• Journal of the Korean Society of Safety
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• v.38 no.4
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• pp.60-67
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• 2023

Various lifting slings are used in domestic industrial sites depending on the purpose, form, and environment. Each sling has its characteristics, and safe lifting work is possible when its performance meets the regulations. Therefore, this study analyzed domestic and foreign regulations and guidelines related to chain slings. It identified significant problems by analyzing the chain-sling-related disaster cases. The current status of chain slings used by various industries and the ways to improve chain sling safety were studied. The major chain sling issues were: 1) employing improper components to chains, 2) having different safety coefficients between the regulation and industrial standards, and 3) using chains unsuitable for lifting purposes. Based on these issues, the following measures were proposed to improve chain sling work safety: 1) revise the safety coefficient requirements under the Regulations on Occupational Safety and Health Standards, 2) disseminate specialized sling courses, and 3) strengthen on-site chain slings-related training. In the future, this study is expected to minimize chain use mistakes by unifying the safety coefficient related to chain slings and recognizing the importance of correctly selecting components employed in the chain.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2021.10a
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• pp.385-387
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• 2021

Marine deposition waste threatens the book ecosystem and causes a decrease in catch due to ghost fishing, causing damage of about 370 billion won per year. In order to collect this, a current status survey is conducted using two-way ultrasonic detectors, diving, and lifting frames. However, the scope of the investigation is small to investigate a lot of sedimentary waste, and there is a possibility of causing casualties. This paper deals with the implementation of a high-accuracy marine deposition detection AI model by learning the coastal sediment image data of AI-Hub using the YOLOv5 algorithm suitable for real-time object detection.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.9 no.1
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• pp.13-19
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• 2004

We compared two different zooplankton data sets simultaneously obtained at the same place with different mesh-sized nets. Smaller mesh-sized net yielded less diverse zooplankton taxa. However, it was difficult to generalize the relationship between the size of the mesh of the net used and the length of the species list observed. It was not only because the sample sizes obtained by smaller mesh net were relatively smaller due to the clogging problem but also because smaller mesh net usually collected more tiny animals that were difficult to identify at lower taxonomic categories. In terms of abundances, on the other hand, the smaller and the larger mesh-sized nets collected smaller and larger-sized animals more effectively, respectively. The abundances of small sized animals were usually greater than those of large-sized animals by about an order of differences. Due to this different catchability of the nets, the community analyses based on Principal Component Analysis led to different results for the same community.