• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.12
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• pp.272-278
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• 2018

Traffic volume has been greatly increasing due to urban development and the improvement of living standards, and many complaints are being raised due to the increasing road noise. As a countermeasure against these problems, highly soundproof walls are installed on the sides of roads. However, the ability to bear wind loads is a major design requirement for soundproof walls, which contributes to the exponential increases in construction costs and restricts the height of the walls. The aim of this study is to improve the performance of soundproof walls and to dramatically reduce wind loads while maintaining excellent price competitiveness. Based on Helmholz's resonator theory, a new concept is proposed for a ventilation-type soundproofing plate that can pass through a fluid like air and reduce noise. A full-scale metal soundproofing plate was produced to satisfy the quality standards of highways by conducting a sound-pressure transmission-loss test, wind tunnel test, and material quality test. To verify the reliability, the wall was manufactured and installed, and the sound insulation effect was examined by measuring the noise over time. In the future, ventilated soundproof walls on roads could create a pleasant living environment due to the high noise-insulation effect.

• Journal of the Korean Society of Marine Environment & Safety
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• v.26 no.7
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• pp.810-819
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• 2020

Recently, the demand for liquefied gas has been increasing for various reasons, including environmental problems, and as a result, transportation of liquefied gas through a ship is increasing, and several terminals are also being constructed to accommodate it. The size of the terminal to be constructed shall follow the result if the target ship is clearly determined. Otherwise, the size of the vessel that the terminal intends to accept shall be determined, and then, the dimensions of the vessel given in the regulations or standards shall be used. In this regard, it was found that the main dimensions of the proposed vessels are substantially different from those actually operating and the standard for large-sized vessels has not been established in the process of determining the size of the target vessel by using the "Port and Fishing Port Design Standards" and commentary(2017), which recently is most commonly used as port design criteria in order to construct the liquefied gas terminal. Because of these problems, a revision of the standard for the major dimensions of liquefied gas carriers was proposed through an analysis of the current status of ships in service, as there could be many differences between interested parties in determining the size of the target ships and terminals and evaluating the safety of terminals. It is expected that the proposed revision will be used as a more appropriate and realistic criterion for determining the size of ships and terminals in the future and will prevent unnecessary terminal construction costs.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.3
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• pp.1-12
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• 2021

Technologies for an MVDC(medium voltage direct current) distribution system are being considered as an effective alternative to overcome the interconnection delay issues of PV systems. However, the implementation of a DC distribution system might lead to economic problems because of the development of DC devices. Therefore, this paper deals with the scale of a PV plant based on its capacity and proposes hosting-capacity models for PV systems to establish a network to evaluate the feasibility of an MVDC distribution system. The proposed models can be classified as AC and DC distribution systems by the power-supply method. PV systems with hundreds of MW, dozens of MW, and a few MW can be categorized as large-scale, medium-scale, and small-scale models, respectively. This paper also performed modeling for an economic evaluation of MVDC distribution system by considering both the cost of AC and DC network construction, converter replacement, operation, etc. The profit was composed of the SMP and REC rate of a PV plant. A simulation for economic evaluation was done for the MVDC distribution system using the present worth and equal-principal costs repayment method. The results confirmed that the proposed model is a useful tool to evaluate economic issues of a DC distribution system.

• Explosives and Blasting
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• v.39 no.4
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• pp.22-33
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• 2021

Recently, the frequent occurrence of ground subsidence in urban areas has caused increasing anxiety in residents and incurred significant social costs. Among the causes of ground subsidence, the rupture of old water and sewer pipes not only halts the operation of the buried pipes, but also leads to ground and water pollution problems. However, because most pipes are buried after construction and cannot be seen with the naked eye, the importance of maintenance has underestimated compared to other structures. In recent years, integrated physical exploration has been applied to the maintenance of underground pipes and structures. Currently, to investigate the internal conditions and vulnerable portions of the ground, consolidated physical surveys are executed. Consolidated physical surveys are analysis techniques that obtain various material data and add existing data using multiple physical surveys. Generally, in geotechnical engineering, consolidated physical surveys including electrical and surface wave surveys are adopted. However, it is difficult to investigate time-based changes in under ground using these surveys. In contrast, surveys using cosmic-ray muons have been used to scan the inner parts of nuclear reactors with penetration technology. Surveys using muons enable real-time observation without the influence of vibration or electricity. Such surveys have great potential for available technology because of their ability to investigate density distributions without requiring as much labor. In this paper, survey technologies using cosmic ray muons are introduced, and the possibilities of applying such technologies as new physical survey technologies for underground structures are suggested.

• Journal of Korea Foundry Society
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• v.41 no.6
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• pp.550-557
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• 2021

With the advent of the fourth industrial revolution, the interest in the internet of things (IoT) in manufacturing is growing, even at foundries. There are several types of process data that can be automatically collected at a foundry, but considerable amounts of process data are still managed based on handwriting for reasons such as the limited functions of outdated production facilities and process design based on operator know-how. In particular, despite recognizing the importance of converting process data into big data, many companies have difficulty adopting these steps willingly due to the burden of system construction costs. In this study, the field applicability of IoT-based devices was examined by manufacturing devices and applying them directly to the site of a centrifugal foundry. For the centrifugal casting process, the temperature and humidity of the working site, the molten metal temperature, and mold rotation speed were selected as process parameters to be collected. The sensors were selected in consideration of the detailed product specifications and cost required for each process parameter, and the circuit was configured using a NodeMCU board capable of wireless communication for IoT-based devices. After designing the circuit, PCB boards were prepared for each parameter, and each device was installed on site considering the working environment. After the on-site installation process, it was confirmed that the level of satisfaction with the safety of the workers and the efficiency of process management increased. Also, it is expected that it will be possible to link process data and quality data in the future, if process parameters are continuously collected. The IoT-based device designed in this study has adequate reliability at a low cast, meaning that the application of this technique can be considered as a cornerstone of data collecting at foundries.

• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.5
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• pp.30-42
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• 2022

Due to the increase in construction of tunnels, the burdens of maintenance works for tunnel structures have been increasing in Korea. In addition, the increase of traffic volume and aging of materials also threatens the safety of tunnel facilities, therefore, maintenance costs are expected to increase significantly in the future. Accordingly, automated condition assessment technologies like image-based tunnel scanning system for inspection and diagnosis of tunnel facilities have been proposed. For image-based tunnel scanning system, it is key to create a planar image through stitching of multiple images captured by tunnel scanning system. In this study, performance of feature-based stitching algorithms suitable for stitching tunnel scanning images was evaluated. In order to find a suitable algorithm SIFT, ORB, and BRISK are compared. The performance of the proposed algorithm was determined by the number of feature extraction, calculation speed, accuracy of feature matching, and image stitching result. As for stitching performance, SIFT algorithm was the best in all parts of tunnel image. ORB and BRISK also showed satisfactory performance and short calculation time. SIFT can be used to generate precise planar images. ORB and BRISK also showed satisfactory stitching results, confirming the possibility of being used when real-time stitching is required.

• Journal of the Korean GEO-environmental Society
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• v.22 no.12
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• pp.5-13
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• 2021

Expandable steel pipe piles have been developed to ensure stability and reduce construction costs during underground floor remodeling and extension work. Expandable steel pipe piles are more economical and stable than micropiles. Extensible steel pipe pile is a method of improving the performance of steel pipes by expanding steel pipes underground. In this paper, the changes in buckling strength according to the shape of steel pipes in an extended steel pipe pile were identified, a numerical analysis model was developed to determine the expended part effect of bumps due to steel pipe expansion, and the optimal steel pipe expansion was calculated through material tests. The larger the expansion diameter of the steel pipe and the greater the number of expanded part, the greater the buckling strength. Numerical results showed that the number of expanded part has a greater effect on buckling strength than the expansion rate. When the expansion rate is more than 1.2 times, it can be seen that as the number of expanded part increases, the effect of increasing buckling strength increases significantly. It was also noted that the expanded part effect of the bumps occur significantly when the extension angle is less than 45° and the expansion rate is 1.3 times higher. When the steel pipe is failure, the expanded rate is 20 to 32%, averaging 25.4%. Through the material test, it was analyzed that it is desirable to limit the maximum expansion rate for performing steel pipes to 16%.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.22 no.2
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• pp.93-104
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• 2023

Currently, the permanent road traffic volume surveys under Road Act are conducted using a intrusive Automatic Vehicle Classification (AVC) equipments to classify 12 categories of vehicles. However, intrusive AVC equipment inevitably have friction with vehicles, and physical damage to sensors due to cracks in roads, plastic deformation, and road construction decreases the operation rate. As a result, accuracy and reliability in actual operation are deteriorated, and maintenance costs are also increasing. With the recent development of ITS technology, research to replace the intrusive AVC equipment is being conducted. However multiple equipments or self-built DB operations were required to classify 12 categories of vehicles. Therefore, this study attempted to prepare a method for classifying 12 categories of vehicles using vehicle specification information of the Vehicle Management Information System(VMIS), which is collected and managed in accordance with Motor Vehicle Management Act. In the future, it is expected to be used to upgrade and diversify road traffic statistics using vehicle specifications such as the introduction of a road traffic survey system using Automatic Number Plate Recognition(ANPR) and classification of eco-friendly vehicles.

• Journal of Platform Technology
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• v.10 no.4
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• pp.25-38
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• 2022

Recently, it is reported that the Korean Unmanned Aerial Vehicle (UAV) interface protocol (K-4586) based on STANAG-4586 is being developed to secure interoperability between UAVs. The core elements of the K-4586-based Unmanned Aircraft System (UAS) are the Core UAV Control System (CUCS), Vehicle Specific Module (VSM), Data Link Interface (DLI), and C4I systems. In UAS based on K-4586, the DLI function for transmitting and receiving messages to link UAVs is included in VSM and CUCS respectively. The Generator/Analyzer (G/A) tool is an apparatus that is developed for protocol conformance verification for VSM and CUCS, and G/A tools with DLI message transmitting and receiving should be developed separately. Core applications (VSM, CUCS, DLI) and G/A tools based on K-4586 may be developed independently depending on the developers. If the DLI message modules are different for each developer, the scope and results of protocol conformance verification will be dissimilar, and some problems may happen during system integration. In this study, common DLI message module based on the API was designed to provide the DLI message transmitting and receiving function necessary to the development of core applications and the protocol conformance verification tool of based on K-4586. When applying the proposed common DLI message module, it can be expected to shorten the UAS system development period and reduce costs, and ensure conformance of protocol. In this paper, the design and implementation method for the common DLI message module based on API was proposed and the results of functional test was described.

• Clean Technology
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• v.29 no.3
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• pp.227-234
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• 2023

Recently, local governments have recognized river zones as leisure spaces and local festival venues, and hence, the pressure for developing these zones has increased significantly. However, given the unique functionalities of river zones and the time and costs associated with maintaining facilities and restoring damaged areas, a development plan must be selected carefully. To preserve river zones and to facilitate nature-friendly space utilization, this study focused on improving environmental impact assessment (EIA), which is an institutional implementation procedure for project plans. This study prepared a draft guide for EIA by providing an overview of the research background and survey outcomes, including the status of laws and regulations on river zones, development plans, and opinions on EIA. The results showed that because strategic EIA of basic river plans is important for district designation of river zones and the scope and direction of space utilization, it is necessary to establish a more meticulous business plan before reviewing and evaluating the mini EIA linked to the future implementation of a plan to derive a reasonable assessment. Additionally, this study provides a draft guide for EIA to evaluate the suitability of water-friendly facility construction plans considering the location characteristics and to reflect the factors that can reduce the environmental impacts during the mini EIA stage. In the future, we expect that the results of this study will serve as a foundation for establishing instructions and guides for the development of nature-friendly and water-friendly facilities in river zones during the establishment of plans.