• Clean Technology
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• v.27 no.1
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• pp.79-84
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• 2021

In this study, the waste activated carbon used in the painting process was filled into a cylindrical cartridge and the characteristics of desorption by low temperature gas were investigated. Adsorption and desorption experiments of toluene with activated carbon were conducted to determine the flow rate of desorption. In an experiment where desorption was performed while changing conditions at flow rates of 1, 2 and 4 ㎥ min-1, it was determined that 2 ㎥ min-1 was appropriate due to the high THC concentration and desorption time. In the early stage of the desorption of waste activated carbon, 2-butanone and MIBK (methyl isobutyl ketone) with a low boiling point were generated at a high rate in the gas component, and after that, the concentration of THC decreased and the BTX was desorbed at a high rate. The total calorific value of the gas component generated during the desorption of waste activated carbon was 316 kcal kg-1. From repeating the regeneration of waste activated carbon with toluene five times, it was observed that the iodine value and the specific surface area were relatively lower than that of new activated carbon. In the desorption experiment where two cylindrical cartridges were connected in series, the maximum THC concentration was about 470 ppm.

• Journal of Environmental Impact Assessment
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• v.30 no.2
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• pp.89-104
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• 2021

This study investigated the public opinion on the use and conservation management of national park, to manage the growing demand of national park visit and to support the policy direction of national park. So far, various surveys and big data analysis on the use and perception of national park have been conducted, but there have been limitations such as lack of survey questions on issues in park management and use. In addition, the object of the previous studies were limited to the national park visitors; therefore, this study expanded the object of survey from national park visitors to ordinary citizens. Unlike previous studies conducted only on national park visitors, ordinary citizens relatively prefered bottom areas rather than high-altitude ones. A policy to limit the visit to high-ridge area of mountain is being currently driven; however, the survey results of ordinary citizens suggested to maintain current policies or to increase visitor reservations system within narrow limits. On the other hand, the proportion of citizens who have used the visitor-reservation system was very small. We discuss the difference between national park visitors and ordinary citizens and the policy conditions according to changes in park management principles and public attitudes toward national parks.

• Journal of the Korea Convergence Society
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• v.12 no.8
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• pp.245-256
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• 2021

The Fourth Industrial Revolution brought the quantitative value of data across the industry and entered the era of 'Big Data'. This is due to both the rapid development of information & communication technology and the diversity & complexity of customer purchasing tendencies. An enterprise's core competence in the Big Data Era is to analyze and utilize the data to make strategic decisions for enterprise. However, most of traditional studies on Big Data have focused on technical issues and future potential values. In addition, these studies lacked interest in managing the quality and utilization levels of internal & external customer Big Data held by the entity. To overcome these shortages, this study attempted to derive influential factors by recognizing the quality management information systems and quality management of the internal & external Big Data. First of all, we conducted a survey of 204 executives & employees to determine whether Big Data quality management, Big Data utilization, and level management have a significant impact on corporate work efficiency & corporate management performance. For the study for this purpose, hypotheses were established, and their verifications were carried out. As a result of these studies, we found that the reasons that significantly affect corporate management performance are support from the management class, individual innovation, changes in the management environment, Big Data quality utilization metrics, and Big Data governance system.

• Membrane Journal
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• v.31 no.6
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• pp.417-425
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• 2021

As the demand for high-capacity batteries increases, there has been growing researches on the lithium metal anode with a capacity (3,860 mAh/g) of higher than that of conventional one and a low electrochemical potential (-3.040 V). In this study, using the anatase phased TiO₂ nanoparticles synthesized by hydrothermal synthesis, a PVdF-HFP/TiO₂ organic/inorganic composite material was designed and used as an interfacial protective layer for a Li metal anode. As-formed organic/inorganic-lithium composite thin film was confirmed through the crystalline structure and morphological analyses. In addition, the electrochemical test (cycle stability and voltage profile) confirmed that the protective layer of PVdF-HFP/TiO₂ composite (10 wt% TiO₂ and 1.1 ㎛ film thickness) contributed to the enhanced electrochemical performance of the lithium metal anode (Colombic efficiency retention: 90% for 77 cycles). Based on comparative test with the untreated lithium electrode, it was confirmed that our protective layer plays an important role to stabilize/improve the EC performance of the lithium metal negative electrode.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.50 no.3
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• pp.181-192
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• 2022

Active vibration control system(AVCS) for helicopter enables to control the vibration generated from the main rotor and has the superb vibration reduction performance with low weight compared passive vibration reduction device. In this paper, FxLMS algorithm-based vibration control software of the light civil helicopter tansmits the control command calculated using the signals of the tachometer and accelerometers to the circular force generator(CFG) is developed and verified. According to the RTCA DO-178C/DO-331, the vibration control software is developed through the model based design technique, and real-time operation performance is evaluated in PILS(processor in-the loop simulation) and HILS(hardware in-the loop simulation) environments. In particular, the reliability of the software is improved through the LDRA-based verification coverage in the PIL environments. In order to AVCS to light civil helicopter(LCH), the dynamic response characteristic model is obtained through the ground/flight tests. AVCS configuration which exhibits the optimal performance is determined using system optimization analysis and flight test and obtain STC certification.

• Journal of the Society of Disaster Information
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• v.18 no.1
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• pp.146-153
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• 2022

Purpose: In the case of domestic port facilities, port structures that have been in use for a long time have many problems in terms of safety performance and functionality due to the enlargement of ships, increased frequency of use, and the effects of natural disasters due to climate change. A big data analysis method was studied to develop an approximate model that can predict the aging pattern of a port facility based on the maintenance history data of the port facility. Method: In this study, member-level maintenance history data for caisson-type quay walls were collected, defined as big data, and based on the data, a predictive approximation model was derived to estimate the aging pattern and deterioration of the facility at the project level. A state-based aging pattern prediction model generated through Gaussian process (GP) and linear interpolation (SLPT) techniques was proposed, and models suitable for big data utilization were compared and proposed through validation. Result: As a result of examining the suitability of the proposed method, the SLPT method has RMSE of 0.9215 and 0.0648, and the predictive model applied with the SLPT method is considered suitable. Conclusion: Through this study, it is expected that the study of predicting performance degradation of big data-based facilities will become an important system in decision-making regarding maintenance.

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.4
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• pp.567-576
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• 2022

Seafarers are exposed to various unpredictable maritime risks due to the spatial specificity of the working environment of the sea; thus, sufficient compensation for injured crewmembers is needed. However, Korea does not provide such compensation. Therefore, this study attempted to examine the Maritime Labor Act and the Industrial Accident Insurance Act of Germany, an advanced European social insurance country, and derive implications compared to Korea. First, we investigated how compensations are managed by a public institution in Germany and by shipowners in Korea. Second, regarding the contents of accident compensation, Germany does not only provide continuous treatment and care through various support systems, but also operates various programs to enable a return to ship work. In contrast, Korea has a temporary compensation system that allows shipowners to avoid liability for accident compensation, which is disadvantageous to shipwrecked seafarers. Finally, in Germany, workers' compensation insurance is public, judged considering the origin of work, whereas in Korea, it is determined by shipowners or insurance companies. Therefore, it is necessary to establish a public institution in charge of crew accident compensation to ensure proper compensation for crewmembers in Korea and to improve the Seafarers Act or system to provide compensation for additional medical care, disability pension, and rehabilitation benefits.

• Composites Research
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• v.35 no.3
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• pp.201-215
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• 2022

This paper presents the development of thin and lightweight ultra-high temperature radar-absorbing ceramic composites composed of an aluminosilicate ceramic matrix-based geopolymer reinforced ceramic fiber and sendust magnetic nanoparticles in X-band frequency range (8.2~12.4 GHz). The dielectric properties with regard to complex permittivity of ceramic/sendust-aluminosilicate composites were proportional to the size of sendust magnetic nanoparticle with high magnetic characteristic properties as flake shape and its concentrations in the target frequency range. The characteristic microstructures, element composition, phase identification, and thermal stability were examined by SEM, EDS, VSM and TGA, respectively. The fabricated total thicknesses of the proposed single slab ultra-high temperature radar absorber correspond to 1.585 mm, respectively, exhibiting their excellent EM absorption performance. The behavior of ultra-high temperature EM wave absorption properties was verified to the developed free-space measurement system linked with high temperature furnace for X-band from 25℃ to 1,000℃.

• Journal of Bio-Environment Control
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• v.31 no.2
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• pp.98-103
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• 2022

Non-destructive estimation of leaf area is a more efficient and convenient method than leaf excision. Thus, several models predicting leaf area have been developed for various horticultural crops. However, there are limited studies on estimating the leaf area of strawberry plants. In this study, we predicted the leaf areas via nonlinear regression analysis using the leaf lengths and widths of three-compound leaves in five domestic strawberry cultivars ('Arihyang', 'Jukhyang', 'Keumsil', 'Maehyang', and 'Seollhyang'). The coefficient of determination (R²) between the actual and estimated leaf areas varied from 0.923 to 0.973. The R² value varied for each cultivar; thus, leaf area estimation models must be developed for each cultivar. The leaf areas of the three cultivars 'Jukhyang', 'Seolhyang', and 'Maehyang' could be non-destructively predicted using the model developed in this study, as they had R² values over 0.96. The cultivars 'Arihyang' and 'Geumsil' had slightly low R² values, 0.938 and 0.923, respectively. The leaf area estimation model for each cultivar was coded in Python and is provided in this manuscript. The estimation models developed in this study could be used extensively in other strawberry-related studies.

• Journal of Korean Home Economics Education Association
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• v.33 no.2
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• pp.27-44
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• 2021

This study is to identify the concept of action from the critical science perspective and to explore the agency of home economics teachers for the purpose of teacher education. The context and various characteristics of home economics teacher' agency were identified in terms of philosophy and teacher education. The results of the study indicates, first, the concept of action refers to an activity of individuals involving one's own intentions, and include the ability to reveal a unique identity that aims to reach a set purpose and decision, and this can be identified by mutual meaning in the public sphere. Second, teacher agency is influenced by a teacher's professional experiences and cultural and structural aspects, and it can create an environment which can promote self-directed and cooperative relationships among individuals and communities. Therefore, home economics teachers should be able to reasonably judge, contemplate, and act through reflections on the circumstances and consequences in which their agency is exercised. Third, home economics teachers can reflect and think critically about the values, roles, and sense of purpose of home economics education based on agency. Teachers should focus on the process of achieving their agency rather than on completing it, and they can continuously develop it through a perceived shared understanding among teachers. Therefore, the conceptualization of the agency of home economics teachers is to understand the practice revealed in a teacher's actions. This requires environmental support in school settings because it acts as a mechanism for strengthening the thinking and reflection of teachers through the creation of interactive environments in which professional knowledge and experiences can be shared.