• Journal of Life Science
• /
• v.31 no.10
• /
• pp.960-968
• /
• 2021

Since microalgae research started on late 18 century, they have been recognized as one of the most important bioresources used in bioindustry. Owing to the large efforts paid to industrial application of this microorganisms, their importance on food/feed and bioactive compounds has been further extending into the environmental research areas including alternative energy resources, mitigation of the carbon emission, and waste-water treatment. However, despite the importance on their industrial application, the fundamental research field related to the long-term preservation of microalgae culture has not received much attention. However, a less labor intensive and cost-efficient preservation technology enabling biologically active and stable microalgae-culture provides a key success factor in the biotechnological application. Therefore, this study investigated various cutting-edge microalgae cryopreservation technologies currently developed so far, mainly targeting Chlorophyta, which occupies the largest taxon in the classification system of microalgae. In addition, for the development of successful cryopreservation technique, the key factors such as temperature control effect and preservative effect during cryopreservation of microalgae culture were investigated. In addition, the problems with current preservation technology that is being used in Korean domestic biological resource banks and the international microalgal resource banks are described. According to our investigation, currently no standard method for long-term preservation of microalgae is available due to their various morphological and physiological characteristics. To overcome such issues, much more efforts on fundamental research area on the identification of specific biomarker used for microalgae taxonomical classification and further systemic approaches based on strain-specific cryopreservation methods needed.

• Membrane Journal
• /
• v.30 no.6
• /
• pp.395-408
• /
• 2020

Polymer electrolyte membrane fuel cells (PEMFCs) have gained much attention as eco-friendly energy conversion devices without emission of environmental pollutant. Polymer electrolyte membrane (PEM) that can transfer proton from anode to cathode and also prevent fuel cross-over has been regarded as a key component of PEMFCs. Although perfluorinated polymer membranes such as Nafion® were already commercialized in PEMFCs, their high cost and toxic byproduct generated by degradation have still limited the wide spread of PEMFCs. To overcome these issues, development of hydrocarbon based PEMs have been studied. Incorporation of cross-linked structure into the hydrocarbon based PEM system has been reported to fabricate the PEMs showing both high proton conductivity and outstanding physicochemical stability. This study focused on the various cross-linking strategies to the preparation of cross-linked PEMs based on hydrocarbon polymers with ion conducting groups for application in PEMFCs.

• (The)Study of the Eastern Classic
• /
• no.73
• /
• pp.91-117
• /
• 2018

In the tribute system controlling international relations of pre-modern East Asia, conciliation diplomacy between royal authorities was a principle of diplomatic relations among each nation. Therefore, capitals where royal authorities really existed were political centers and diplomatic stages at the same time. Notably, diplomatic relations between United Silla and Japan were maintained dually by conciliation diplomacy between royal authorities and practical diplomacy through Dazaihu located in Tsukushi. Tsukushi located at the northwestern tip of Kyushu was a gateway to foreign nations and stronghold in terms of national defense. Amidst an East Asian war named Baek River Battle in 663, the royal court of Daehwa established Dazaihu here because it was necessary for diplomatic and military responses. Dazaihu established as part of diplomatic negotiation not only took diplomatic functions as an official residence since the latter half of the 7thcentury. and but also was used as a stage of official diplomacy between Silla and Japan. Diplomatic negotiation between Silla and Japan through Dazaihu was made in practical methods and such a situation could be confirmed through diplomatic documents exchanged between Silla and Dazaihu in the middle of the 8thcentury. At that time, protocols became an importan tissue.

• Composites Research
• /
• v.35 no.3
• /
• pp.127-133
• /
• 2022

Polypropylene (PP) has been received great attention as a next-generation high-voltage power cable insulation material that can replace cross-linked polyethylene (XLPE). However, the PP cannot be used alone as an insulation material because of its high elastic modulus and vulnerability to impact, and thus is mainly utilized as a form of a copolymer with rubber phases included in the polymerization step. In this paper, a soft PP-based blend was prepared through melt-mixing of impact PP, polyolefin elastomer, and propylene-ethylene random copolymer. The elastic modulus and impact strength of the blend could properly be decreased or increased, respectively, by introducing elastomeric phases. Furthermore, the blends showed a high storage modulus even at a temperature of 100℃ or higher at which the XLPE loses its mechanical properties. In addition, the blend was found to be effective in suppressing the space charge compared to the pristine PP as well as XLPE.

• The Journal of the Korea Contents Association
• /
• v.22 no.3
• /
• pp.538-546
• /
• 2022

For the recent 5 years, the trends showed that the child abuses by parents was declined while that by child care teachers and principals, employees in child welfare institution was increased. In particular, significant increase of child abuses by child care teachers and principals should be paid attention more than the abuse by the others. The government had already enacted the Act on Punishment against Child Abuses in 2014 to respond and prevent from child abuses strongly. However, as the cases of child abuses continued, questions were raised on the effectiveness of the regulation or whether the court performed well to play a role to punish the assailants of child abuses by amended regulations was suspected. This study is aimed to review the application cases of the Act on Punishment against Child Abuses through the precedents of child abuses in child care centers and to analyze how the punishments to assailants have been changed compared to application of Child Welfare Act. This study has the meaning to grasp the incompleteness of legal application on the child abuse cases and provide the basic data to improve the legal and system.

• Journal of The Korean Association of Information Education
• /
• v.26 no.3
• /
• pp.187-195
• /
• 2022

Recently, with interest in metaverse, attempts are being made to utilize the metaverse platform in various forms. In this paper, we focused on the educational application potential of metaverse, and developed and applied a metaverse STEAM program to provide an effective learning experience to learners in non-face-to-face educational situations. The developed program utilizes Minecraft and ZEPETO, familiar to students, as metaverse learning platforms, and consists of a total of 16 lessons of 5 modules in the form of modules so that alternative classes can take place in the educational field. Through this, the learner's change in STEAM attitude and learning satisfaction were measured, and through the developed STEAM program, the learner's interest, consideration, communication, usefulness, self-concept, self-efficacy, and career choice areas significantly increased. In addition, positive results were confirmed in all areas of the learner satisfaction test related to satisfaction, interest, and overall class. In the future, considering the characteristics of the metaverse, it is necessary to break free from the constraints of time and space to communicate anew, and various learner-centered educational approaches based on a high degree of freedom and immersion should be implemented.

• Journal of the Korean Society for Library and Information Science
• /
• v.56 no.2
• /
• pp.35-55
• /
• 2022

As altmetrics has received a lot of attention as an muti-dimensional impact assessment tool, it is necessary to verify whether it can supplement the citation-based research performance evaluation system. This study analyzed and compared the effects of each altmetrics sources on citation by sampling 1,600 high-cited papers published in the last 10 years (Sample A) and non-year-limited papers (Sample B) indexed in Scopus. In addition, it was analyzed whether the OA of the paper had a moderating effect on the numbers of cited-by, and the difference according to the samples was verified. As a result of the analysis, only the number of Mendeley bookmark readers was analyzed to have a positive (+) effect on the numbers of cited-by, and OA status had a significant moderating effect in both groups. However, in sample A, OA showed a reinforcing effect on cited-by, whereas Sample B showed a weakening effect, showing a difference. On the other hand, social mention such as media reports do not have a significant effect on the cited-by regardless of OA conditions, but they can be used to understand the social impact of non-academic mass readers.

• KIPS Transactions on Software and Data Engineering
• /
• v.11 no.8
• /
• pp.339-346
• /
• 2022

Recently, the resource depletion and climate change problem caused by the massive usage of fossil fuels for electric power generation has become a critical issue worldwide. According to this issue, interest in renewable energy resources that can replace fossil fuels is increasing. Especially, photovoltaic power has gaining much attention because there is no risk of resource exhaustion compared to other energy resources and there are low restrictions on installation of photovoltaic system. In order to use the power generated by the photovoltaic system efficiently, a more accurate photovoltaic power forecasting model is required. So far, even though many machine learning and deep learning-based photovoltaic power forecasting models have been proposed, they showed limited success in terms of interpretability. Deep learning-based forecasting models have the disadvantage of being difficult to explain how the forecasting results are derived. To solve this problem, many studies are being conducted on explainable artificial intelligence technique. The reliability of the model can be secured if it is possible to interpret how the model derives the results. Also, the model can be improved to increase the forecasting accuracy based on the analysis results. Therefore, in this paper, we propose an explainable photovoltaic power forecasting scheme based on BiLSTM (Bidirectional Long Short-Term Memory) and SHAP (SHapley Additive exPlanations).

• Membrane Journal
• /
• v.32 no.6
• /
• pp.411-426
• /
• 2022

Energy plays a significant role in modern lifestyle because of our extensive reliance over energy-operating devices. Therefore, there is a need for alternative and green energy resources that can fulfill the energy demand. For this, fuel cell (FCs) especially anion exchange membrane fuel cells (AEMFCs) have gained tremendous attention over the other (FCs) due to their fast reaction kinetics without using noble catalyst and allow to use of cheaper polymers with high performance. But lack of highly conductive, chemically, and mechanically stable anion exchange membrane (AEM) still main obstacle to the development of high performance AEMFCs. Therefore, graphene-based polymer composite membranes came into the existence as AEMs for the FCs. The exceptional properties of the graphene help to improve the performance of AEMs. Still, there are lot of challenges in the graphene derivatives based AEMs because of their high tendency of agglomeration in polymer matrix which reduced their potential. To overcome this issue surface modification of graphene derivatives is necessary to restrict their agglomeration and conserved their potential features that can help to improve the performance of AEM. Therefore, this review focus on the surface modification of graphene derivatives and their role in the fabrication of AEMs for the FCs.

• Journal of Korean Society of Forest Science
• /
• v.112 no.3
• /
• pp.363-373
• /
• 2023

Forest biomass surveys are regularly conducted to assess and manage forests as carbon sinks. LiDAR (Light Detection and Ranging), a remote sensing technology, has attracted considerable attention, as it allows for objective acquisition of forest structure information with minimal labor. In this study, we propose a method for estimating overstory and understory biomass in forest stands using backpack laser scanning (BPLS) and unmanned aerial vehicle laser scanning (UAV-LS), and assessed its accuracy. For overstory biomass, we analyzed the accuracy of BPLS and UAV-LS in estimating diameter at breast height (DBH) and tree height. For understory biomass, we developed a multiple regression model for estimating understory biomass using the best combination of vertical structure metrics extracted from the BPLS data. The results indicated that BPLS provided accurate estimations of DBH (R² =0.92), but underestimated tree height (R² =0.63, bias=-5.56 m), whereas UAV-LS showed strong performance in estimating tree height (R² =0.91). For understory biomass, metrics representing the mean height of the points and the point density of the fourth layer were selected to develop the model. The cross-validation result of the understory biomass estimation model showed a coefficient of determination of 0.68. The study findings suggest that the proposed overstory and understory biomass survey methods using BPLS and UAV-LS can effectively replace traditional biomass survey methods.