• Korean Chemical Engineering Research
• /
• v.60 no.4
• /
• pp.473-477
• /
• 2022

In this study, candidate technologies for lithium recovery from the process waste liquid generated in the waste battery recycling process were reviewed, and technologies applicable to the process from the commercialization point of view were reviewed from a qualitative point of view. The evaporation method is difficult to apply because it requires a large-scale land and shows a low recovery rate due to the loss of Li during the concentration process. In the case of precipitation, a commercially available technology shows a high recovery rate due to the high Li/Na selectivity of phosphoric acid, but there are disadvantages in that the process is complicated due to the use of expensive phosphoric acid, requiring a recovery step, and continuous operation is impossible because solids are handled in the Li concentration process. In the case of solvent extraction, if we find an inexpensive extractant with high Li/Na selectivity, continuous operation is possible with the method used in extraction of other metals in the previous step, and when Li is concentrated, continuous operation is possible because it is in a liquid state. If it shows a similar recovery rate compared to precipitation technology, commercialization will be the most likely.

• The Journal of Society for e-Business Studies
• /
• v.26 no.4
• /
• pp.95-118
• /
• 2021

As the AI speaker business has risen significantly in recent years, the potential for numerous uses of AI speakers has gotten a lot of attention. Consumers have created an environment in which they can express and share their experiences with products through various channels, resulting in a large number of reviews that leave consumers with a variety of candid opinions about their experiences, which can be said to be very useful in analyzing consumers' thoughts. Using this review data, this study aimed to examine the factors driving the continued use of AI speakers. Above all, it was determined whether the seven characteristics associated with the intention to adopt AI identified in prior studies appear in consumer reviews. Based on customer review data on Amazon.com, text mining and social network analysis were utilized to examine Amazon eco-products. CONCOR analysis was used to classify words with similar connectivity locations, and Connection centrality analysis was used to classify the factors influencing the continuous use of AI speakers, focusing on the connectivity between words derived by classifying review data into positive and negative reviews. Consumers regarded personality and closeness as the most essential characteristics impacting the continued usage of AI speakers as a result of the favorable review survey. These two parameters had a strong correlation with other variables, and connectedness, in addition to the components established from prior studies, was a significant factor. Furthermore, additional negative review research revealed that recognition failures and compatibility are important problems that deter consumers from utilizing AI speakers. This study will give specific solutions for consumers to continue to utilize Amazon eco products based on the findings of the research.

• The Journal of the Convergence on Culture Technology
• /
• v.8 no.3
• /
• pp.191-201
• /
• 2022

In this study, we are going to derive problems for fire and safety management in multiple-user Buildings and suggest improvement measures to prevent recurrence through analysis of legal operation status for safety management of multiple-user Buildings and case studies of large-scale fires in multiple-user Buildings. For this study, first, the current state of the industry and fire occurrence status were investigated through theoretical considerations of the multi-use industry, and then the previous research on the multi-use industry was analyzed. and by analyzing the legal and institutional status of multiple-user Buildings, problems were derived through cases such as the Jecheon fire in Chungcheongbuk-do, the Inhyeon-dong fire in Incheon, and the Songpa-gu fire in Seoul. As a result, first, the necessity of strengthening the initial fire response capability. Second, thorough maintenance and management of emergency exits. Third, the need for rational regulation of upholstery. Fourth, reinforcement of fire safety education and training. Fifth, strengthening of installation standards for firefighting and safety facilities. Sixth, we derive the result that it is necessary to raise awareness about safety management, compare and analyze it with legal and institutional contents, and suggest solutions accordingly. When looking at the causes of fires in multi-use buildings, building owners, business owners, and employees think that there is no possibility of a fire occurring in their business premises, so there is a lack of awareness. It is necessary to raise awareness through education and publicity of firefighters and related administrative agencies.

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

• Smart Media Journal
• /
• v.12 no.2
• /
• pp.66-75
• /
• 2023

Recently, the number of cloud web applications is increasing owing to the accelerated migration of enterprises and public sector information systems to the cloud. Traditional network attacks on cloud web applications are characterized by Denial of Service (DoS) attacks, which consume network resources with a large number of packets. However, HTTP DoS attacks, which consume application resources, are also increasing recently; as such, developing security technologies to prevent them is necessary. In particular, since low-bandwidth HTTP DoS attacks do not consume network resources, they are difficult to identify using traditional security solutions that monitor network metrics. In this paper, we propose a new detection model for detecting HTTP DoS attacks on cloud web applications by collecting the application metrics of web servers and learning them using machine learning. We collected 18 types of application metrics from an Apache web server and used five machine learning and two deep learning models to train the collected data. Further, we confirmed the superiority of the application metrics-based machine learning model by collecting and training 6 additional network metrics and comparing their performance with the proposed models. Among HTTP DoS attacks, we injected the RUDY and HULK attacks, which are low- and high-bandwidth attacks, respectively. As a result of detecting these two attacks using the proposed model, we found out that the F1 scores of the application metrics-based machine learning model were about 0.3 and 0.1 higher than that of the network metrics-based model, respectively.

• Nuclear Engineering and Technology
• /
• v.25 no.4
• /
• pp.539-547
• /
• 1993

A stochastic approach using continuous time Markov process is presented to model the one-dimensional nuclide transport in fractured rock media as a further extension for previous works［1-3］. Nuclide transport of decay chain of arbitrary length in the single planar fractured rock media in the vicinity of the radioactive waste repository is modeled using a continuous time Markov process. While most of analytical solutions for nuclide transport of decay chain deal with the limited length of decay chain, do not consider the case of having rock matrix diffusion, and have very complicated solution form, the present model offers rather a simplified solution in the form of expectance and its variance resulted from a stochastic modeling. As another deterministic way, even numerical models of decay chain transport, in most cases, show very complicated procedure to get the solution and large discrepancy for the exact solution as opposed to the stochastic model developed in this study. To demonstrate the use of the present model and to verify the model by comparing with the deterministic model, a specific illustration was made for the transport of a chain of three member in single fractured rock medium with constant groundwater flow rate in the fracture, which ignores the rock matrix diffusion and shows good capability to model the fractured media around the repository.

• Journal of the Korean Geotechnical Society
• /
• v.24 no.6
• /
• pp.77-84
• /
• 2008

The existing equations for radial consolidation cannot account for the changes of well resistance with time and cannot predict the appropriate in-situ consolidation curve. In this study, small cylinder cell tests are performed to evaluate the discharge capacity of PVD. Also, a block sample of 1.2 m in diameter and 2.0 m in height was consolidated to observe the change in the drainage capacity with time for three types of PVD. From the test results on a block sample, the drainage curves normalized with initial drainage of each PVD are similar, regardless of the PVD type and the consolidation curve, which is predicted using solutions of radial consolidation based on the discharge capacity measured in a small cylinder cell tests, significantly overestimates the degree of consolidation. The term of well resistance in the radial consolidation solution was back-calculated to fit the consolidation curve of a large block sample and it is defined as the time dependent well resistance factor, L(t). The L(t) was found to be linearly proportional to the dimensionless time factor, Th. It was also shown that the consolidation curve evaluated by using L(t) provides more accurate prediction than the existing solution.

• Smart Media Journal
• /
• v.13 no.5
• /
• pp.52-61
• /
• 2024

The onset of the COVID-19 pandemic has accelerated social transformations across various nations. These changes, particularly prominent in the corporate and industrial sectors, have necessitated a shift towards increased remote activities, fundamentally altering societal structures. Within this context, the concept of the Metaverse, a virtual world existing since the early 2000s but previously underrecognized, began to gain widespread recognition. In South Korea, major tech companies such as Naver, Kakao, and Coupang have long normalized remote working, with new employee orientations also taking place on Metaverse platforms. Beyond the IT sector, institutions requiring large gatherings, such as schools, have adopted the Metaverse for hosting major events like welcome ceremonies and informational sessions. This phenomenon suggests that the Metaverse is not merely a transient social trend but is gradually integrating into the daily lives of the general populace, serving as a significant social connector. This study explores the potential of Metaverse-enabled design thinking and methodologies to address the Environmental, Social, and Governance (ESG) challenges faced by Korean society. Specifically, the research focuses on developing solutions for social issues related to pets in Korea.

• Journal of the Korea Institute of Building Construction
• /
• v.24 no.1
• /
• pp.145-156
• /
• 2024

In an era where construction projects are becoming increasingly large and complex, the Korean construction industry faces the challenge of implementing systematic and cohesive schedule management practices. This study initially delineates the concept of schedule management capabilities, systematically categorizing them into five distinct domains: law and regulations, requirements of project owners, capabilities of professionals and organizations, task capability, and the adoption of smart construction technologies for schedule management. Through a survey targeting industry professionals, this research assesses the perceived importance and the actual proficiency level in schedule management across these categories, employing an Importance Performance Analysis(IPA) to scrutinize these capabilities. The findings underscore the acknowledged significance of diverse aspects of schedule management, yet reveal discrepancies between the current proficiency levels and their perceived importance, pinpointing areas necessitating enhancement. Critical improvement needs identified encompass the planning of budgets for schedule management, development of regulations for assessing construction periods, deployment of specialized on-site staff for schedule management, and investment in advanced schedule management software solutions. Consequently, this study offers a nuanced analysis and strategic insights for enhancing schedule management practices, aiming to facilitate their effective implementation in the field.

• The Journal of the Convergence on Culture Technology
• /
• v.10 no.3
• /
• pp.53-59
• /
• 2024

The novel "The Grapes of Wrath" shows the painful reality of Americans during the Great Depression through the migration journey of the Tom Jod's family, who had no choice but to move from Oklahoma to California and their hardships in California. This presents empathy for their wrath and offers hope for a brotherly solution. This article presents institutional solutions against each novel situation from the perspective of the Constitution, labor law, and competition law. From a constitutional perspective, the poverty of Oklahoma's smallholders is not a result of choice, but is caused by the natural environment and capital concentration, so it is suggested that the government have to intervene to guarantee a minimum standard of living to realize equal rights. From a labor law perspective, worker supply projects are unconstitutional because they constitute intermediate exploitation of labor, and immigrants like the Joad family have the right to form labor unions. From a competition law perspective, it was shown that the large landowners' setting of fruit prices constitutes predatory pricing, and the farmers' attempts to pay similarly low wages constitute collusion. Through this, the attempt was made to recognize that the law is a means to resolve the public wrath that may currently exist, and to show that the story in the novel can bring empathy and understanding to minorities. It is hoped that reading novels can be a way to help interpret the law and sympathize with others as an indicator of a just society.