• Journal of the Korean Geosynthetics Society
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• v.17 no.4
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• pp.267-275
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• 2018

The dredged sediment management system was developed to have an objective, quantitative and scientific decision for the optimum removal time of dredged sediments behind debris barrier and was set up at the real site. The dredged sediment management system is designed and developed to directly measure the dredged sediments behind debris barrier in the field. This management system is composed of Data Acquisition System (DAS), Solar System and measurement units for measuring the weight of dredge sediments. The weight of dredged sediments, the water level and the rainfall are measured in real time using the monitoring sensors, and their data can be transmitted to the office through a wireless communication method. The monitoring sensors are composed of the rain gauge to measure rainfall, the load cell system to measure the weight of dredged sediments, and water level meter to measure the water level behind debris barrier. The management criteria of dredged sediments behind debris barrier was suggested by using the weight of dredged sediments. At first, the maximum weight of dredged sediments that could be deposited behind debris barrier was estimated. And then when 50%, 70% and 90% of the maximum dredged sediments weight were accumulated behind debris barrier, the management criteria were divided into phases of Outlooks, Watch and Warning, respectively. The weight of dredged sediments can be monitored by using the dredged sediment management system behind debris barrier in real time, and the condition of debris barrier and the removal time of dredged sediments can be decided based on monitoring results.

• KIPS Transactions on Computer and Communication Systems
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• v.8 no.6
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• pp.127-138
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• 2019

The data response speed is a critical issue of cloud services because it directly related to the user experience. As such, the in-memory database is widely adopted in many cloud-based applications for achieving fast data response. However, the current implementation of the in-memory database is mostly based on the linked list-based hash table which cannot guarantee the constant data response time. Thus, cuckoo hashing was introduced as an alternative solution, however, there is a disadvantage that only half of the allocated memory can be used for storing data. Subsequently, bucketized cuckoo hashing (BCH) improved the performance of cuckoo hashing in terms of memory efficiency but still cannot overcome the limitation that the insert overhead. In this paper, we propose a data management solution called Wall Cuckoo which aims to improve not only the insert performance but also lookup performance of BCH. The key idea of Wall Cuckoo is that separates the data among a bucket according to the different hash function be used. By doing so, the searching range among the bucket is narrowed down, thereby the amount of slot accesses required for the data lookup can be reduced. At the same time, the insert performance will be improved because the insert is following up the operation of the lookup. According to analysis, the expected value of slot access required for our Wall Cuckoo is less than that of BCH. We conducted experiments to show that Wall Cuckoo outperforms the BCH and Sorting Cuckoo in terms of the amount of slot access in lookup and insert operations and in different load factor (i.e., 10%-95%).

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.18 no.1
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• pp.74-82
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• 2019

The revolution of industry 4.0 is enabling us to build an intelligent connection society called smart cities. The use of renewable energy in particular solar energy is extremely important for modern society due to the growing power demand in smart cities, but its difficult to monitor and manage in each buildings since need to be deploy low energy sensors and information need to be transfer via wireless sensor network (WSN). The Internet of Things (IoT) / low-power wide-area (LPWA) is an emerging WSN technology, to collect and monitor data about environmental and physical electrical / electronics devices conditions in real time. However, providing power to IoT sensor end devices and other public electrical loads such as street lights, etc is an important challenging role because the sensor are usually battery powered and have a limited life time. In this paper, we proposes an efficient solar energy-based power management scheme for smart city based on IoT technology using LoRa wide-area network (LoRaWAN). This approach facilitates to maintain and prevent errors of solar panel based energy systems. The proposed solution maximizing output the power generated from solar panels system to distribute the power to the load and the grid. In this paper, we proved the efficiency of the proposed system with Simulink based system modeling and real-time emulation.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.9
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• pp.7-13
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• 2019

Unlike a typical video wall system, video wall systems used for integrated monitoring in smart city environments should be able to display various videos, images, and texts simultaneously. In this paper, we propose an Internet Protocol (IP)-based video wall system that has no limit on the number of videos that can be monitored simultaneously, and that can arrange the monitor screen layout without restrictions. The proposed system is composed of multiple display servers, a wall controller, and video source providers, and they communicate with each other through an IP network. Since the display server receives and decodes the video stream directly from the video source devices, and displays it on the attached monitor screens, more videos can be simultaneously displayed on the entire video wall. When one video is displayed over several screens attached to multiple display servers, only one display server receives the video stream and transmits it to the other display servers by using IP multicast communications, thereby reducing the network load and synchronizing the video frames. Experiments show that as the number of videos increases, a system consisting of more display servers shows better decoding and rendering performance, and there is no performance degradation, even if the display server continues to be expanded.

• Journal of Korean Society on Water Environment
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• v.34 no.6
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• pp.688-702
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• 2018

Since the 1970s regulations against the pollution of drinking water have been introduced in Lake Paldang watershed area. To understand the effects of water environment management policies and the impacts of climate changes on Lake Paldang, a long-term comprehensive study of this watershed and the changes in its water environment is required. In this study, we analyzed changes in the weather, hydrology, sources of pollution, water quality, and algal development from 2000 to 2015 year based on the statistical data provided by several national information systems. While the population and amount of sewage in the Lake Paldang watershed increased by about 1.5 times, the amount of animal manure showed a decreasing trend during the same period. The wastewater also increased by about 1.5 times while the amount of water intakes rose by about 1.14 times. The water quality in front of the Paldang Dam, which is the representative monitoring site of the Lake Paldang, was stable. The annual average BOD concentration remained within 2 mg/L, which is a "Good (lb)" level according to the environment standards of Republic of Korea. The development of phytoplankton and harmful cyanobacteria were largely influenced by meteorological factors.

• Smart Structures and Systems
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• v.24 no.6
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• pp.769-781
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• 2019

Dynamic displacement response of civil structures is an important index for in-construction and in-service structural condition assessment. However, accurately measuring the displacement of large-scale civil structures such as high-rise buildings still remains as a challenging task. In order to cope with this problem, a vision-based system with the use of industrial digital camera and image processing has been developed for long-distance, remote, and real-time monitoring of dynamic displacement of supertall structures. Instead of acquiring image signals, the proposed system traces only the coordinates of the target points, therefore enabling real-time monitoring and display of displacement responses in a relatively high sampling rate. This study addresses the in-situ experimental verification of the developed vision-based system on the Canton Tower of 600 m high. To facilitate the verification, a GPS system is used to calibrate/verify the structural displacement responses measured by the vision-based system. Meanwhile, an accelerometer deployed in the vicinity of the target point also provides frequency-domain information for comparison. Special attention has been given on understanding the influence of the surrounding light on the monitoring results. For this purpose, the experimental tests are conducted in daytime and nighttime through placing the vision-based system outside the tower (in a brilliant environment) and inside the tower (in a dark environment), respectively. The results indicate that the displacement response time histories monitored by the vision-based system not only match well with those acquired by the GPS receiver, but also have higher fidelity and are less noise-corrupted. In addition, the low-order modal frequencies of the building identified with use of the data obtained from the vision-based system are all in good agreement with those obtained from the accelerometer, the GPS receiver and an elaborate finite element model. Especially, the vision-based system placed at the bottom of the enclosed elevator shaft offers better monitoring data compared with the system placed outside the tower. Based on a wavelet filtering technique, the displacement response time histories obtained by the vision-based system are easily decomposed into two parts: a quasi-static ingredient primarily resulting from temperature variation and a dynamic component mainly caused by fluctuating wind load.

• Journal of Industrial Convergence
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• v.20 no.3
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• pp.33-40
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• 2022

Recently, IoT-linked services have been used in various environments, and IoT and artificial intelligence technologies are being fused. However, since technologies that process IoT data stably are not fully supported, research is needed for this. In this paper, we propose a processing technique that can optimize IoT data after generating embedded vectors based on machine learning for IoT data. In the proposed technique, for processing efficiency, embedded vectorization is performed based on QR such as index of IoT data, collection location (binary values of X and Y axis coordinates), group index, type, and type. In addition, data generated by various IoT devices are integrated and managed so that load balancing can be performed in the IoT data collection process to asymmetrically link IoT data. The proposed technique processes IoT data to be orthogonalized based on hash so that IoT data can be asymmetrically grouped. In addition, interference between IoT data may be minimized because it is periodically generated and grouped according to IoT data types and characteristics. Future research plans to compare and evaluate proposed techniques in various environments that provide IoT services.

• Journal of Internet Computing and Services
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• v.22 no.6
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• pp.129-140
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• 2021

The next generation mBcN should be built to cooperate with the wireless network to support hyper-speed and hyper-connectivity. In this paper, we propose a network architecture for the cooperation mBcN and 5G commercial network and architecture of the cooperative security gateway required for the cooperation. The proposed cooperative security gateway is between gNB and UPF to support LBO, SFC, and security. Our analysis shows that the proposed architecture has several advantages. First of all, user equipment connected with the mBcN can be easily connected through the 5G commercial radio network to the mBcN. Second, the military application traffic can be transmitted to mBcN without going through the 5G core network, reducing the end-to-end transmission delay without causing the traffic load on the 5G core network. In addition, the security level of the military application can effectively be maintained because the user equipment can be connected to the cooperative security gateway, and the traffic generated by the user equipment is transmitted to the mBcN without going through the 5G core network. Finally, we demonstrate that LBO, SFC, and security modules are essential functions of the proposed gateway in the 5G test-bed environment.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.35 no.6
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• pp.631-638
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• 2022

Microgrid, which enables the production and consumption of electricity to be done independently on a small scale, has been studied on one of the solutions of reinforcement for flexibility of electronic system. This study examined the application effect of new microgrid by applying hybrid battery in electric power storage device. We designed the system to highlight the advantage of each battery and complement the disadvantage by using hybrid system with Lithium-ion battery and interval Redox flow battery. It runs with lithium-ion battery during the initial startup while the Redox flow battery operates for a long time at the end of excessive period, and it enables a discharge of Lithium-ion and Redox flow battery at the same time when the load has a large output. We chose Maldives as a subject of this study for organizing and optimizing independent microgrid. Maldives is the country to accomplish 100% domestic electricity in South Asia, but the whole electric power is supplied through diesel generation imported fossil fuel. We organized and optimized microgrid for energy independence on Malahini island to solve Maldives energy cost problem and global energy environment matters. We analyzed the daily power supply and accumulated the power supply from September 18, 2018~February 11, 2019. The accumulated power supply was about 120.4 MWh and the daily power supply was about 800~1000 kWh. Based on the collected information, we divided the cases into three models which are only diesel generator, solar generator as well as diesel generator, and solar+ESS+diesel generator. We analyzed the amount of oil consumption compared to the cost of construction and power output. The result showed that solar+ESS+diesel generator was most economically feasible. As well, we obtained that our considering hybrid battery system reduced the fuel consumption for diesel power generation about 10~15%.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.21 no.5
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• pp.57-66
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• 2022

The Road Management Administration is cracking down on overloaded vehicles by installing low-speed or high-speed WIMs at toll gates and main lines on expressways. However, in recent years, the act of intelligently evading the overloaded-vehicle control system of the Road Management Administration by illegally manipulating the variable axle of an overloaded truck is increasing. In this manipulation, when entering the overloaded-vehicle checkpoint, all axles of the vehicle are lowered to pass normally, and when driving on the main road, the variable axle of the vehicle is illegally lifted with the axle load exceeding 10 tons alarmingly. Therefore, this study developed a technology to detect the state of the variable axle of a truck driving on the road using roadside camera images. In particular, this technology formed the basis for cracking down on overloaded vehicles by lifting the variable axle after entering the checkpoint and linking the vehicle with the account information of the checkpoint. Fundamentally, in this study, the tires of the vehicle were recognized using the Mask RCNN algorithm, the recognized tires were virtually arranged before and after the checkpoint, and the height difference of the vehicle was measured from the arrangement to determine whether the variable axle was lifted after the vehicle left the checkpoint.