• Journal of the Korea Institute of Building Construction
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• v.16 no.6
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• pp.587-594
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• 2016

This study aims to analyze the benefit-cost of the cleaning device for photovoltaic power generation systems in buildings in order to check its economic feasibility. A product, which has similar characteristics to the ultrasound-based cleaning device and is widely used in South Korea, was selected to compare with the benefit-cost value of the ultrasound-based cleaning device in this study. In order to quantitatively and qualitatively analyze benefit and cost aspects of the two products, categories and evaluation factors of each aspect as well as evaluation criteria were identified. Based on the identified evaluation factors and criteria, this study conducted face-to-face interviews with 15 experts to measure weights of benefit and cost aspects of the products. As the results, the total benefit weight of the ultrasound-based cleaning device was larger than its total cost weight since the benefit-cost value was greater than 1, which was 1.6 times of that of to compared product. Therefore, from the economic perspective, it is worth to develop the cleaning device for photovoltaic power generation systems applying ultrasound technology.

• Journal of Navigation and Port Research
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• v.43 no.6
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• pp.429-436
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• 2019

The eLoran system is considered the best alternative because the vulnerability of satellite navigation systems cannot be resolved as perfect. Thus, South Korea is in the process of establishing a testbed of the eLoran system in the West Sea. To provide resilient navigation services to all waters, additional eLoran transmitters are required. However, it is difficult to establish eLoran transmitters because of various practical reasons. Instead, the positioning with NDGNSS/AIS source can expand the coverage and its algorithm with applying continuous waves is under development. Using the already operating NDGNSS reference station and the AIS base station, it is possible to operate the navigation system with higher accuracy than before. Thus, it is crucial to predict the performance when each system is integrated. In this paper, we have developed a simulation tool that can predict the performance of terrestrial integrated navigation system using the eLoran system, maritime NDGNSS station and the AIS station. The esitmated phase error of the received signal is calculated with the Cramer-Rao Lower Bound factoring the transmission power and the atmospheric noise according to the transmission frequency distributed by the ITU. Additionally, the simulation results are more accurate by estimating the annual mean atmospheric noise of the 300 kHz signal through the DGPS signal information collected from the maritime NDGNSS station. This approach can further increase the reliability of simulation results.

• Journal of the Earthquake Engineering Society of Korea
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• v.25 no.2
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• pp.71-81
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• 2021

This paper presents a real-time, false-pick filter based on deep learning to reduce false alarms of an onsite Earthquake Early Warning (EEW) system. Most onsite EEW systems use P-wave to predict S-wave. Therefore, it is essential to properly distinguish P-waves from noises or other seismic phases to avoid false alarms. To reduce false-picks causing false alarms, this study made the EEWNet Part 1 'False-Pick Filter' model based on Convolutional Neural Network (CNN). Specifically, it modified the Pick_FP (Lomax et al.) to generate input data such as the amplitude, velocity, and displacement of three components from 2 seconds ahead and 2 seconds after the P-wave arrival following one-second time steps. This model extracts log-mel power spectrum features from this input data, then classifies P-waves and others using these features. The dataset consisted of 3,189,583 samples: 81,394 samples from event data (727 events in the Korean Peninsula, 103 teleseismic events, and 1,734 events in Taiwan) and 3,108,189 samples from continuous data (recorded by seismic stations in South Korea for 27 months from 2018 to 2020). This model was trained with 1,826,357 samples through balancing, then tested on continuous data samples of the year 2019, filtering more than 99% of strong false-picks that could trigger false alarms. This model was developed as a module for USGS Earthworm and is written in C language to operate with minimal computing resources.

• Convergence Security Journal
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• v.14 no.6_1
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• pp.129-138
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• 2014

South Korea should correspond to the primary threat to North Korea's nuclear weapons. It is necessary to have countermeasures to solve the realistic problems of North Korea's nuclear weapons. We can intensify military pact between the United States and Korea and at the same time strengthening the current military power. Currently, we take note the threat North Korea's missile. We can not control the development of a nuclear weapon and there are possibilities that North Korea have successfully miniaturized nuclear enough to carry by the missile. We should overview and check the Korea's missile defenses system. While the direction of the overall missile defense system deployment with a focus on lower and upper air defense network. And discuss defense research should be to build a system that can be protected with a key strategic facilities and cities. While North Korea have nuclear weapon, the main issues related to North Korea's nuclear threat. The six party talks countries try to solve the problem by the international and diplomatic approach. At the same time we should make somewhat to defend measures such as military defenses of Kill chain system to protect our country. Kill Chain is on of the effective defense system. We know that North Korea do not abandon to develop nuclear weapons by diplomatic efforts. We should performed in fact by a variety of military suppression method.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.1
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• pp.47-53
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• 2007

The aim of this study is to research applicable possibility or Dry Sorbent Injection Technique(DSI) in sox removal process using Computational Fluid Dynamics(CFD) software package. It will be applied for 500MW in capacity coal-fired thermal power plant operated by South Korea N. Power Co., Ltd. The DSI process is adapted between a preheater and an EP process in the technological assembly. The numerical analysis performs in predicting and optimizing of DSI process's characteristics, which consists of structure of duct, position of injection nozzles, injection speed, and dispersion of sorbent. Computing results are shown that degree of sorbent dispersion depends on structure of duct and position of injection nozzles strongly. The highest dispersion efficiency was obtained when we set a Lobed-plate inside the duct and 6 injection nozzles on the duct(4 injection nozzles at the corners and 2 injection nozzles on upper and under walls as a rectangle duct shape). We also know that change of injection speed of sorbent doesn't have an large effect on the sorbent dispersion but it can effect to drop pressure.

• Nuclear Engineering and Technology
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• v.54 no.1
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• pp.84-96
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• 2022

In the worst case, a temporary ignition source (also known as transient combustibles) between two electrical panels can damage both panels. Mitigation strategies for electrical panel fires were previously developed using fire modeling and risk analysis. However, since they do not comply with deterministic fire protection requirements, it is necessary to analyze the boundary values at which combustibles may damage targets depending on various factors. In the present study, a sensitivity analysis of input variables related to the damage threshold of two electrical panels was performed for dimensionless geometry using a Fire Dynamics Simulator (FDS). A new methodology using a damage evaluation map was developed to assess the damage of the electrical panel. The input variables were the distance between the electrical panels, the vertical height of the fuel, the size of the fire, the wind speed and the wind direction. The heat flux was determined to increase as the vertical distance between the fuel and the panel decreased, and the largest heat flux was predicted when the vertical separation distance divided by one half flame length was 0.3-0.5. As the distance between the panels increases, the heat flux decreases according to the power law, and damage can be avoided when the distance between the fuel and the panel is twice the length of the panel. When the wind direction is east and south, to avoid damage to the electrical panel the distance must be increased by 1.5 times compared to no wind. The present scale model can be applied to any configuration where combustibles are located between two electrical panels, and can provide useful guidance for the design of redundant electrical panels.

• Smart Structures and Systems
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• v.6 no.5_6
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• pp.439-459
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• 2010

Structural health monitoring (SHM) of civil infrastructure using wireless smart sensor networks (WSSNs) has received significant public attention in recent years. The benefits of WSSNs are that they are low-cost, easy to install, and provide effective data management via on-board computation. This paper reports on the deployment and evaluation of a state-of-the-art WSSN on the new Jindo Bridge, a cable-stayed bridge in South Korea with a 344-m main span and two 70-m side spans. The central components of the WSSN deployment are the Imote2 smart sensor platforms, a custom-designed multimetric sensor boards, base stations, and software provided by the Illinois Structural Health Monitoring Project (ISHMP) Services Toolsuite. In total, 70 sensor nodes and two base stations have been deployed to monitor the bridge using an autonomous SHM application with excessive wind and vibration triggering the system to initiate monitoring. Additionally, the performance of the system is evaluated in terms of hardware durability, software stability, power consumption and energy harvesting capabilities. The Jindo Bridge SHM system constitutes the largest deployment of wireless smart sensors for civil infrastructure monitoring to date. This deployment demonstrates the strong potential of WSSNs for monitoring of large scale civil infrastructure.

• The Journal of the Convergence on Culture Technology
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• v.9 no.2
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• pp.227-233
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• 2023

Along with the 4th Industrial Revolution, the impact of "unmanned" is affecting all fields around the world, and in particular, in the military sector, "unmanned" is so important that it occupies a part of the main combat system. Recently, the South Korean military is facing a crisis due to the North Korea's UAV incident that invaded our airspace and descended to Seoul. In response, the South Korea military declared its willingness and countermeasures to capture and destroy North Korea's UAV. However, as the technological development of UAV continues and the utilization plan is expanding, the countermeasures for UAV at the current level can be useless. Also, the threat from North Korea is not just UAV. North Korea has practically a nuclear power and is set to conduct its seventh nuclear test, and its missile technology is also being advanced, with 38 arounds of 67 missile tests conducted in 2022 alone. It is also developing five key strategic weapons that can pose a fatal threat to Korea, and North Korea's strong conventional forces are located around the NLL(Northern Limit Line), and the port of Long Range Artillery is facing the Seoul metropolitan area. It is important to respond to North Korea's UAV threats, which are now receiving much attention, but it will be necessary to comprehensively analyze and clearly prioritize North Korea's threats and use a limited budget to respond to them.

• Journal of International Area Studies (JIAS)
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• v.15 no.1
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• pp.83-108
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• 2011

South America has vast energy resources with the renewable and non-renewable sources. However, many countries in the region are unable to guarantee adequate energy security both of energy supply and demand. Currently the possibility of energy security is high through regional energy integration based on the potential economic benefits. The difference of regulation system with the individual countries in the region impose strong barriers to integration process. Security of energy supply and its demand as well is fundamental issues in this region and regional energy cooperation is essential for getting rid of the insecurity of energy supplies. Despite of this problem, currently Latin American countries made a great effort to make multilateral energy security regime through projecting great energy infrastructure network(e.g. IIRSA) or mechanism especially in South America, which can give countries access to the region's reserve supplies by providing regulations and pricing mechanism with a shared energy market in this region. Brazil's active leading in the formulation of such movement toward energy security integration and participation of energy infrastructure network is good initiative to enforce this great energy security change. Politically and economically, Brazil's geographical position and the level of market size and oil and natural gas resources, in addition the leadership in renewable energy sources make it a sound candidate to take over the coordination of the secure integration of region's energy market. However, on the conditions of existing many obstacles such as, control of the output of the region's power plant, energy flows, the environmental matter within local community must be overcome to make more advance process and steps. Finally, to secure more institutional approach, this region must settle regional disputes resolution regime urgently.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.26 no.4
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• pp.985-994
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• 2016

Since the inauguration of Defense Acquisition Program Administration(DAPA) in 2006, the national defense core technology research & development business has not only pertained to the weapons systems development but also to the improvement of the national science & technology capability via the acquisition of cutting-edge technologies. Furthermore, it has been closely related to the promotion of the defense industry and the mutual improvements of defense and civil technologies. The cyber warfare weapon system, a newly added national defense weapon system field since 2015, has become a promising weapon system branch for improving the national defense power as well as the national defense industry as shown in the case of Israel. By utilizing the existing result of the national defense core technology level, in order to establish the direction of technology planning of the cyber warfare weapon system, this paper analyzes the technology level and features of the cyber warfare weapon system in various aspects via comparisons with other weapons systems. The result of these analyses shows that the cyber warfare weapon system possesses a relatively high technology level due to the technology accumulation in the civilian sector while the relatively slow inclusion to the national weapons systems and the lack of the correspondence case regarding aggressive cyber responses in the defense sector yields a relatively low national rank. However, the technological gap between South Korea and the most advanced country in the field of cyber warfare technology is analyzed to be among the lowest, which indicates that with efficient and effective pursuits in terms of pthe weapons systems acquisitions as well as the core technologies research & development business, an outstanding cyber warfare capacity can be obtained in a short time.