• Journal of the Microelectronics and Packaging Society
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• v.21 no.4
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• pp.133-137
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• 2014

As a preceding process for preparing several micrometer sized Ag-coated Cu flakes, ball milling of submicrometer-sized Cu particles synthesized through a wet chemical method was performed in order to convert the particles into flakes. To suppress oxidation and aggregation of the particles during ball milling, ethylene glycol and ethyl acetate were used as a medium and a surface modifying agent, respectively. Results obtained with different rotation speeds of a jar indicated that the rotation speed changes a rotating mode, and strikingly alters the final shapes and shape uniformity of Cu particles after milling. The diameter of zirconia ball was also confirmed. Although there was aggregates in the initial submicrometer-sized Cu particles, therefore, well-dispersed Cu flakes with a size of several micrometers were successfully prepared by ball milling through optimization of rotation speed, amount of ethyl acetate, and diameter of zirconia ball.

• Convergence Security Journal
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• v.23 no.5
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• pp.81-89
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• 2023

Kubernetes is a representative open-source software for container orchestration, playing a crucial role in monitoring and managing resources allocated to containers. As container environments become prevalent, security threats targeting containers continue to rise, with resource exhaustion attacks being a prominent example. These attacks involve distributing malicious crypto-mining software in containerized form to hijack computing resources, thereby affecting the operation of the host and other containers that share resources. Previous research has focused on detecting resource depletion attacks, so technology to respond when attacks occur is lacking. This paper proposes a reinforcement learning-based dynamic resource management framework for detecting and responding to resource exhaustion attacks and malicious containers running in Kubernetes environments. To achieve this, we define the environment's state, actions, and rewards from the perspective of responding to resource exhaustion attacks using reinforcement learning. It is expected that the proposed methodology will contribute to establishing a robust defense against resource exhaustion attacks in container environments

• Transactions of the Korean Society of Mechanical Engineers B
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• v.39 no.12
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• pp.927-934
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• 2015

In this study, we numerically investigated the concentration characteristics of a linear Fresnel reflector system that can drive a solar thermal absorption refrigeration system to be installed in Saudi Arabia. Using an optical modeling program based on the Monte Carlo ray-tracing method, we simulated the concentrated solar flux, concentration efficiency, and concentrated solar energy on four representative days of the year - the vernal equinox, summer solstice, autumnal equinox, and winter solstice. Except the winter solstice, the concentrations were approximately steady from 9 AM to 15 PM, and the concentration efficiencies exceed 70%. Moreover, the maximum solar flux around the solar receiver center changes only within the range of $13.0{\sim}14.6kW/m^2$. When we investigated the effects of the receiver installation height, reflector width, and reflector gap, the optimal receiver installation height was found to be 5 m. A smaller reflector width had a greater concentration efficiency. However, the design of the reflector width should be based on the capacity of the refrigeration system because it dominantly affects the concentrated solar energy. The present study was an essential prerequisite for thermal analyses of the solar receiver. Thus, an optical-thermal integration study in the future will assist with the performance prediction and design of the entire system.

• Journal of the Korea Convergence Society
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• v.11 no.1
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• pp.211-219
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• 2020

This paper examines in depth the UN's disaster risk reduction system and framework that affect a country's disaster safety strategy and focuse on identifying the global trends in disaster risk reduction that have emerged in the Hyogo and the Sendai Framework, a disaster risk reduction strategy proposed by the UN since 2000. For this aim it attempts a theoretical review based on collecting a variety of domestic and international literatures, draws meaningful implications and suggests alternatives to a national disaster risk reduction policy. According to the analysis, the UN disaster risk reduction mechanism is UNISDR, the Secretariat is UNDRR, and the SRSG represents it, and the Sendai Framework, developed from the Hyogo Code of Conduct, a global strategy which has been for disaster safety for the past decade, will lead global disaster safety for the next decade. The policy implications drawn from the analysis of both strategies are the emphasis on consistent international coordination, strengthening resilience and an integrated and comprehensive approach. In conclusion, this paper proposes the need for a disaster risk reduction strategy to establish a resilience reinforcement system to proactively identify and cope with risk factors and to minimize impacts, to promote the coordination of international coordination and cooperation at the government level.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.1
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• pp.138-147
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• 2020

The construction field is one of the most representative job creation businesses, but it has been pointed out that the overall quality of the jobs is low because of the nature of the order-made production industry, such as unstable employment structure, aging workforce, etc.. Accordingly, the government plans to implement the "prevailing wage system" that guarantees a minimum wage for construction site workers. In reality, however, only a market wage could be used for a construction cost estimation because there was no standard for the prevailing wage. A comparative analysis of the prevailing wage and market wage was performed. This paper proposes a framework for estimating the reasonable prevailing wage in the construction industry. The results showed that the prevailing wage was estimated to be 4.7% lower than the market wage when the proposed framework is applied to the carpenters' case. This suggests that the proposed model could be used as an alternative for market wage considering the original purpose of the prevailing wage. This study will construct the basic data for scientific analysis on the wage, and finally, help estimate the reliable prevailing wage in the future.

• KIPS Transactions on Computer and Communication Systems
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• v.7 no.3
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• pp.81-90
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• 2018

Due to the dramatic advancement of IoT (Internet of Things), it is expected that tens of billions of IoT devices will be connected by the year 2024. Furthermore, as IoT technologies evolves, the security management in IoT platforms has become a critical issue. For example, there are interworking problems between heterogeneous IoT platforms caused by differences from communication protocols, security policies, etc. in each platform. In addition, unsecured interworking can cause major security issues including the information leakage. In this paper, in order to solve these problems, a security interworking architecture is proposed and implemented in both FIWARE and oneM2M, which are representative IoT platforms. First, the security architecture of FIWARE is analyzed and implemented, and then the security framework based on OAuth 2.0 is developed on Mobius platform. Finally, in order to validate the proposed security interworking architecture, a LED (Light-Emitting Diode) example, where the LED is controlled by only authorized users, is developed. The proposed architecture can be extended to the diverse IoT platforms and devices.

• Journal of Digital Convergence
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• v.18 no.10
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• pp.537-546
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• 2020

This study aims to find the structure of social disussion on government 'Senior job program' by analyzing 1107 newspaper articles on 'senior job program' from 11 major newspaper articles and 8 financial newspapers. Topic modeling via latent dirichlet allocation model was employed for analysis and as result, 5 latent topics were extracted as follows : general information, local government project propaganda, senior life related issues, employment creation effect and market relations. Until 2015, most of the articles focused on the first two topics, indicating not much discourse was formed concerning the characteristics of the program. However, after 2015, the third topic started to increase and after the launch of Moon Jae In government, there has been a drastic increase in the employment creation related topic indicating that current social discourse mirrored by the media is definitely focused on employment creation aspect of senior job program. Based on the result, this study suggests the necessity to increase the quality and also enhance employment aspects of Senior job program.

• Informatization Policy
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• v.24 no.1
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• pp.3-29
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• 2017

The purpose of this research is to understand immersive media such as virtual reality, augmented reality, mixed reality, 360-degree videos etc. from the perspective of user-based approach. 3D videos were once expected as the next-generation industry, but soon it further evolved into UHD and are now followed by immersive media represented by virtual reality. As the virtual reality plays an important role, the current research tries to bring up implications that can be applied to the industrial field along with academic understanding through six theoretical approaches related to virtual reality such as media richness, interactivity, presence, body-ownership, user experience, and visual perception. These six theories were used in immersive media studies such as 3D videos. Media richness and interactivity are the main factors forming positive or negative attitude, presence explains why users are immersed, user experience accounts for total psychological reaction, and visual perception explains how complex the experience of seeing is. Especially, although there is less media research applied, the body-ownership is likely to be not only used in virtual reality research, but immersive media research. The user-based theories related to virtual reality will provide various implications for immersive media researchers as well as hardware and content creators of virtual reality.

• Journal of Broadcast Engineering
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• v.26 no.4
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• pp.368-376
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• 2021

Artificial intelligence clouds help to efficiently develop the autonomous things integrating artificial intelligence technologies and control technologies by sharing the learned models and providing the execution environments. The existing autonomous things development technologies only take into account for the accuracy of artificial intelligence models at the cost of the increment of the complexity of the models including the raise up of the number of the hidden layers and the kernels, and they consequently require a large amount of computation. Since resource-constrained computing environments, could not provide sufficient computing resources for the complex models, they make the autonomous things violate time criticality. In this paper, we propose a digital twin software development framework that selects artificial intelligence models optimized for the computing environments. The proposed framework uses a load estimation DNN model to select the optimal model for the specific computing environments by predicting the load of the artificial intelligence models with digital twin data so that the proposed framework develops the control software. The proposed load estimation DNN model shows up to 20% of error rate compared to the formula-based load estimation scheme by means of the representative CNN models based experiments.

• Asia-pacific Journal of Multimedia Services Convergent with Art, Humanities, and Sociology
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• v.8 no.4
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• pp.285-296
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• 2018

Among many hacking attempts carried out in the past few years, the cyber-attacks that could have caused a national-level disaster were the attacks against nuclear facilities including nuclear power plants. The most typical one was the Stuxnet attack against Iranian nuclear facility and the cyber threat targeting one of the facilities operated by Korea Hydro and Nuclear Power Co., Ltd (Republic of Korea; ROK). Although the latter was just a threat, it made many Korean people anxious while the former showed that the operation of nuclear plant can be actually stopped by direct cyber-attacks. After these incidents, the possibility of cyber-attacks against industrial control systems has become a reality and the security for these systems has been tightened based on the idea that the operations by network-isolated systems are no longer safe from the cyber terrorism. The ROK government has established a realistic control systems defense concept and in the US, the relevant authorities have set up several security frameworks to prepare for the threats. This paper presented various cyber security attack cases and their scenarios against control systems, along with the analysis of countermeasures for them. Though this task, we attempt to identify the items that need to be considered when designing a domestic security framework to improve security and secure stability.