• Journal of the Korea institute for structural maintenance and inspection
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• v.17 no.4
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• pp.84-90
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• 2013

In this study we propose an effective method, Coating processing methods, which can improve the quality of recycled aggregate relatively easily without new equipment investment and complex treatment process and verify the improved effect using the devised method, Coating processing methods. To attain the research aim we used adequately diluted silicate solution for coating and carried out several property valuation for twelve types of material with different coating method. Also we formed concrete with coated aggregates which showed the best property. In conclusion the aggregates with the method of repeated impregnation in the silicate and drying showed the most excellent quality while other coating methods also resulted in an improvement of aggregate quality but failed to meet the KS Standard. Lastly with the optimal material we could obtain the approved compressive strength from the concrete allowing it to be utilized for road facility of which standard compressive strength of design is under 24MPa.

• Membrane Journal
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• v.23 no.1
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• pp.24-44
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• 2013

The MBR technology has evolved rapidly over the past two decades with significant gains in performance and reliability, and reductions in costs. Membrane bioreactors (MBR) technology is widely recognised as offering a key option for enhanced wastewater treatment or reuse. The objective of this paper is then to critically review the remarkable achievement on the research and commercial applications of membrane bioreactor (MBR) technology and to present current and potential MBR markets on a global scope. This brief review of the technology incorporates five key aspects : 1) evolution of MBR practice, 2) the commercial technologies of MBRs, 3) the largest MBR installations globally (e.g. > $10,000m^3/day$), 4) MBR market growth, and 5) directions for future research. Finally, the development directions of economical, environmental and technical aspects in MBRs; 1) investment costs; 2) effluent water quality; 3) membrane materials and modules; 4) MBR equipment and treatment process; 5) operating costs (higher energy & chemical consumption); and 6) sustainability such as anaerobic MBRs in the coming years were addressed.

• KIPS Transactions on Computer and Communication Systems
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• v.6 no.8
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• pp.329-342
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• 2017

Recently, interest and investment in the Internet of Things (IoT) have increased significantly, and security issues are constantly being raised. As a solution, the IETF ACE Working Group is establishing the ACE framework standard, which is a new security framework for various constrained IoT environments based on the existing OAuth 2.0. However, additional work is required to apply the ACE framework, which proposes a new lightweight security system, to the existing Internet environment, and this additional cost is a factor that hinders the application of OAuth 2.0 to the IOT environment. Therefore, we propose an IoT authentication framework based on OAuth 2.0's existing development motivation, and implement a proposal framework based on CoAPthon and analyze its performance.

• Journal of Korean Society for Quality Management
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• v.47 no.3
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• pp.497-508
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• 2019

Purpose: The purpose of this study is to overcome limitations of conventional studies that to predict Baltic Dry Index (BDI). The study proposed applications of Artificial Neural Network (ANN) named Long Short-Term Memory (LSTM) to predict BDI. Methods: The BDI time-series prediction was carried out through eight variables related to the dry bulk market. The prediction was conducted in two steps. First, identifying the goodness of fitness for the BDI time-series of specific ANN models and determining the network structures to be used in the next step. While using ANN's generalization capability, the structures determined in the previous steps were used in the empirical prediction step, and the sliding-window method was applied to make a daily (one-day ahead) prediction. Results: At the empirical prediction step, it was possible to predict variable y(BDI time series) at point of time t by 8 variables (related to the dry bulk market) of x at point of time (t-1). LSTM, known to be good at learning over a long period of time, showed the best performance with higher predictive accuracy compared to Multi-Layer Perceptron (MLP) and Recurrent Neural Network (RNN). Conclusion: Applying this study to real business would require long-term predictions by applying more detailed forecasting techniques. I hope that the research can provide a point of reference in the dry bulk market, and furthermore in the decision-making and investment in the future of the shipping business as a whole.

• Journal of Korean Society on Water Environment
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• v.37 no.4
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• pp.263-274
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• 2021

This study presents the achievements and limitations of the voluntary-based Total Maximum Daily Load (TMDL) through statistical analysis of water quality monitoring data and performance assessments of TMDL plans implemented in the Gyeongan watershed. The results clearly showed that responsible local governments complied the allocated TMDL and the designated water quality goals were successfully achieved in the required period. This was possible because the Ministry of Environment provided innovative incentives, such as, relaxations of the existing tight land-use regulations and full-scale financial aids for constructing and operating public treatment facilities to draw local government voluntary participation. However, a couple of problems which decreased the effectiveness and efficiency of the voluntary TMDL were identified. The different TMDL implementation schedules between upstream (Yongin) and downstream (Gwangju) governments caused delay in water quality improvement and exaggerated TMDL allocation to the local development which made excessive investment in the treatment facilities. Although it is not directly related to the voluntary scheme, technical methods for establishing and assessing the water quality goals should be improved so that the effects of flow conditions on water quality are properly assessed. We expect that results of this case study contribute to developing a more effective voluntary-based scheme for the implementation of the so-called 'tributary TMDL' in the future.

• Knowledge Management Research
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• v.22 no.3
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• pp.17-29
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• 2021

The purpose of this study is to analyze investment performance by applying dynamic methodologies that reflect market expectations rather than traditional static methodologies in applying the glide path of target date fund. In calculating market expectations, the number of distributed shares in the ETF market was used, and the dynamic glide path model portfolio considering market expectations in the analysis period from late 2011 to October 2020 could show better results than the existing static glide path. According to the analysis, increasing the portion of risky assets at a time when the number of shares in the ETF's distribution increases, and in the opposite case, reducing the portion of risky assets is advantageous for profit. The results of this study are expected to provide useful theoretical and practical implications for researchers and asset management workers who are interested in knowledge management from a broad perspective beyond the boundary of pension asset management to the public fund market and ETF market.

• Journal of Korea Society of Digital Industry and Information Management
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• v.17 no.4
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• pp.177-195
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• 2021

The purpose of this study is to examine the trouble of recruitment and research and development of ICT SMEs. Recently, many ICT SMEs have emerged for selling products and services using the technology of the 4th industrial revolution. However, SMEs have relatively deficient resources compared to large companies, the difficulty of maintenance or growth of human resources and intangible resources. This research methodology organized the four stages of the analysis process. The first analysis is the association rules for human resource recruitment. The second analysis is the difficulty of hiring jobs and experienced workers by each stage of company growth. The third analysis is a regression analysis of the trouble of R&D activity. The last analysis is an analysis of association rules on the difficulties of management activities by company growth. As the research result, the first analysis has shown a difference in favored human resources by the ICT industry. The second analysis also showed factor differences in job recruitment difficulties for each stage of corporate growth. In the third analysis, the operation of research institutes in ICT SMEs is influenced by industry type, corporate certification, corporate growth stage, self-technology development, joint technology development, technology transfer, and commercialization. As the last analysis, ICT SMEs showed factor differences in difficulties in management activities by stage of corporate growth. This study contributed empirically emphasizing the troubling phenomenon of human resources and R&D necessary for the growth of ICT SMEs. As a theoretical implication, this research contributed to the research-area expansion of management information using big-data technologies. In particular, this research practically suggests the differentiated direction of recruitment and R&D by ICT SMEs based on industry and each stage of company growth through the association rules of big data.

• Journal of the Korea Convergence Society
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• v.9 no.12
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• pp.17-24
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• 2018

This study attempted to analyze technology convergence structure and key technology research sectors in bio-health. For this, network analysis was performed based on the patent outcomes achieved through national R&Ds. Then, a patent network was analyzed to derive problems and collect data from the National Science & Technology Information Service. With the five groups obtained through the analysis of IPC network and national R&D patents in bio-health based on a research frame network, topics were chosen based on the bio-healthcare technology system. Then, the technology with the greatest ripple effects was derived and compared to other sectors, suggesting a direction for national R&D investments. It is anticipated that this study would make a contribution to a search for R&D investment direction by additionally analyzing overseas patent data and improving correlation analysis between technology convergence and government-led R&D expenses.

• International Area Studies Review
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• v.14 no.1
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• pp.299-319
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• 2010

This thesis analyzed that which countries won the Olympic medals more efficiently at the Olympic Games. Unlike the previous studies, I measured efficiency under the CRS, found implications for investment to improve sports skills through understanding the characteristics of sports race. A methods for research is a DEA-based approach which measures efficiency by using the data only, not assuming the parameters. The inputs are total population and GDP, the output is Olympic medals at 2004 Athens Olympic Games and 2006 Turin Winter Olympic Games. I applied different weights based on the medal colors. The results showed the tendencies that the larger the scales of total population and GDP were, the lower efficient values were. These tendencies imply that sports skills are related with the law of diminishing returns and international convergence. According to these phenomenons, surging investments for sports performance are hard to get proper justification. In the case of limited resources, investing uniformly in various sport entries is more productive than in just one or two sport entries.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.3
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• pp.33-40
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• 2019

FDM 3D printers have become widespread, and investment in the 3D printer industry is increasing. Therefore, many 3D printers are released and the functions of products are emphasized. However, to lower unit prices, open-type 3D printers are sold in kit form, and their performance is very low. If the 3D printer has many heat sources and is sealed, there is the possibility that the main accessories (the main board, power supply, and motor) will be damaged by trapped heat. At the same time, if the ambient temperature is low due to the properties of the material, the output quality deteriorates. In this study, we analyzed the temperature rise of the main accessories and the quality of the output by the heat bed when a chamber was added to an open-type 3D printer. We also compared the quality of the output due to the air flow with the temperature rise of the main accessories. Moreover, we found the optimal value. As a result of the quality analysis, it was finally confirmed that the case with the chamber at $95^{\circ}C$ was the best for the printing condition. In addition, in the absence of the chamber, the bending of the specimen was found to be large, and in the case of the chamber, the degree of bending was slightly decreased by 0.05 mm.