• Journal of Naturopathy
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• v.10 no.2
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• pp.108-113
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• 2021

Background: Results on the action of antioxidants in extracts of Equisetum hyemale stems and roots have already been reported, but the antioxidant properties have not been analyzed. Purpose: This study was to determine the molecular structure of antioxidants in substances extracted from E. hyemale stems and roots. Methods: Component analysis was analyzed by HPLC and LC-MS after extraction with hot water and ethyl alcohol. Results: The HPLC chromatogram of stem and root extracts showed four significant peaks at a wavelength of 205 nm. Peak 1 at 280 nm is a typical simple phenolic type, and both peaks 2-4 near 280 nm and 370 nm are typical flavonoid glycosides. As for the antioxidant level of the extract by HPLC analysis, the sum of the peaks at 740 nm was the highest at 3,669 mAU in the 100% ethanol extract, 3,096 mAU in the 70% ethanol extract, and 2,868 mAU in the hot water extract. As a result of LC-MS analysis of the antioxidant extract, kaempferol-3-sophoroside-7-glucoside with a molecular weight of 772 da at peak 3, and kaempferol-3-sophoroside-8-glucoside with a molecular weight of 788 and 772 at peak 4 was identified. Conclusions: The above results show that two types of antioxidants were identified in the antioxidant extract of E. hyemale exrtracts. Therefore, the potential as a raw material for functional cosmetics has increased.

• Journal of the Society of Disaster Information
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• v.16 no.4
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• pp.638-649
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• 2020

Purpose: The objective of this study is to evaluate the load carrying capacity of a target bridge structure based on the simple slab bridge of concrete over 20 years of public service. Method: By performing static loading test and dynamic loading test, the displacement, strain, impact factor, and natural frequency values were measured and evaluated through analysis method. Result: The main results of this study are as follows. First, the maximum displacement and maximum strain of S1 were assessed at 2.917 mm and 44.720 𝜇ε( tensile) and -13.760 𝜇ε(compression), respectively, with S2 maximum displacement and maximum strain being 2.100 mm and 4.870 𝜇ε(tensile), respectively. Second, the maximum measured impact factor was 0.191 in section S1 A-A, and the maximum measured impact factor was 0.155 in section S2 C-C. Third, the natural frequency was assessed at 6.086 Hz, and the measurement was found to be within the range of 6.152 Hz to 6.738 Hz. Conclusion: The tested bridge may be evaluated to show good behavior and characteristics for the design load.

• Applied Chemistry for Engineering
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• v.33 no.2
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• pp.126-132
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• 2022

Alkaline fuel cells using liquid fuels such as hydrazine and ammonia are gaining great attention as a clean and renewable energy solution possibly owing to advantages such as excellent energy density, simple structure, compact size in fuel container, and ease of storage and transportation. However, common shortcomings including cathode flooding, fuel crossover, side yield reactions, and fuel security and toxicity are still challenging issues. Real time monitoring of fuel concentrations integrated into a fuel cell device can help improving fuel cell performance via predicting any loss of fuels used at a cathode for efficient energy production. There have been extensive research efforts made on developing real-time sensing platforms for hydrazine and ammonia. Among these, recent advancements in electrochemical sensors offering high sensitivity and selectivity, easy fabrication, and fast monitoring capability for analysis of hydrazine and ammonia concentrations will be introduced. In particular, research trend on the integration of metallic and metal oxide nanoparticles and also their hybrids with carbon-based nanomaterials into electrochemical sensing platforms for improvement in sensitivity and selectivity will be highlighted.

• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.6
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• pp.230-237
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• 2022

It is essential that service life of reinforced concrete structures in economic and safety aspects should be secured. It is well-known that chloride attack is a typical deterioration mechanism in field concrete structures. To prevent serious accidents like collapse, many studies have been conducted to increase resistance of chloride ingress using concrete mixed with GGBS. The usage of GGBS concrete is nowadays mandatory. Since most concretes in the field are unsaturated, study regarding chloride absorption is necessary, but many studies have focused on the chloride diffusion phenomenon. Methods for evaluating chloride absorption are cost and improper in the field. It is necessary to develop a simple method for evaluating chloride absorption in practice. This study evaluated resistance of chloride ingress in GGBS concretes with impedance measurement and absorption test. From the results, it was confirmed that the contents of absorbed chloride were linearly correlated with the measured electrical resistivities (or conductivities) in the concrete. At the end of the test, the electrical conductivities were 250.8 S/m (w/b=0.4) and 303.1 S/m (w/b=0.6) for PC concretes, and 2.6 S/m (w/b=0.4) and 64.4 S/m (w/b=0.6) for GGBS concretes, respectively. Considering influencing factors for chloride absorption and impedance measurement, chloride ingress into concrete is mainly affected by pore structures due to replacement of GGBS. Especially, formations of pore structure are different with binder, thereby binders should be considered in building reinforced concrete structures exposed to chloride environments.

• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.6
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• pp.47-53
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• 2022

As the limit state design method is applied as a method of designing concrete structures, the ultimate state is considered in the analysis or design. In fact, when the reinforced concrete member bears tensile force, the force is transmitted from the rebar to the concrete, and the structure bears the tensile force to the ultimate state even after yield. Therefore, the accurate evaluation of behavior after yield, it is necessary to study the tension stiffening effect after yield of the flexural member. In this study, a 4-point bending test was conducted on the RC simple beam having a rectangular cross section of the double reinforcement, and the behavior of the member was analyzed in detail using the image analysis method. Using the analysis results, the estimation formula for the tension stiffening effect after yield was proposed, and the applicability of this was verified through the experimental results of existing study. The difference between the ultimate strain and the yield strain representing the ductile behavior of the member is similar to the experimental results. The prediction of the proposed formula is relatively accurate.

• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.6
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• pp.39-46
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• 2022

As the limit state design method is applied as the design method of reinforced concrete structure, the ultimate state is considered when analyses or designing. In fact, when the reinforced concrete member is bent, there is a confining effect by stirrup, but the material curve of unconfined concretes applied when designing. In this study, to evaluate the suitability of the confined concrete model for flexural members, a 4-point bending test was conducted on RC simple beam with a double-reinforced rectangular cross-section, and the behavior of the member after yield was analyzed in detail using image processing method. For detailed analysis, the DIC method was adopted as an image analysis method, and the validity of DIC method was verified by comparing the measurement results with the LVDT. The distribution of the strain on the concrete surface calculated as a result of the DIC method could be obtained, and the average strain distribution of the cross-section was calculated. Using the average strain distribution, the stress distribution applied existing confined concrete model as a material curve could be derived. Through the comparison of the experimental results and the existing model application results, the suitability of the confined concrete model for RC flexural members having a rectangular cross-section was evaluated.

• Journal of Intelligence and Information Systems
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• v.28 no.4
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• pp.365-385
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• 2022

The easy payment service is a payment and remittance service that uses a simple authentication method. As online transactions have increased due to COVID-19, the use of an easy payment service is increasing. At the same time, electronic financial industries such as Naver Pay, Kakao Pay, and Toss are diversifying the competition structure of the easy payment market; meanwhile overseas fintech companies PayPal and Alibaba have a unique market share in their own countries, while competition is intensifying in the domestic easy payment market, as there is no unique market share. In this study, the participants in the easy payment market were classified as electronic financial companies, mobile phone manufacturers, and financial companies, and a SWOT analysis was conducted on the representative services in each industry. The analysis examined the user reviews of Google Play Store via a topic modeling analysis, and it employed positive topics as strengths and negative topics as weaknesses. In addition, topic modeling was conducted by dividing news articles into political, economic, social, and technology (PEST) articles to derive the opportunities and threats to easy payment services. Through this research, we intend to confirm the service capabilities of easy payment companies and propose a service activation strategy that allows gaining the upper hand in the market.

• The Journal of Society for e-Business Studies
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• v.26 no.4
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• pp.119-131
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• 2021

With the boom of platform businesses, digital transformation has become the most important topic for businesses. Digital transformation has now become the most urgent strategy for survival, from a strategy considered as an option to choose in the past. Many companies are desperately seeking the ways to be digitally transformed. Even though there have been many studies on digital transformation, most of them are on strategic and conceptual model levels based on simple case analyses. In this study, we analyze the benefits of data integration and network effects from it, based on platform business model at the core of digital transformation. The change based on platform can be categorized into the internal one for the integration of data and better decision making, and the external one for the expansion of the businesses and better prediction of consumer behaviors through the integration of external data sets by the platform business model based enterprises. While the progress for digital transformation is not mature enough yet, financial industry is one of the most promising industries for the change and realization of the aim of it with its relatively much more advanced IT infrastructure. Many companies are making various efforts for the integration of external data, and if the good results can be accomplished, financial industry will contribute to the advancement of digital transformation in other industries as well. For "My Data" project by Korean government, we suggest the data structure and transaction of data (of Korea) should be advanced and established more quickly.

• The Journal of the Korea Contents Association
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• v.22 no.2
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• pp.147-161
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• 2022

This study examined changes in the ecological characteristics and design characteristics of Ban's exhibition space in three representative temporary exhibition halls and three permanent exhibition halls designed by Ban Shigeru since 2000. Through the investigation of the concepts and characteristics of ecological architecture, the design characteristics of exhibition space, the analysis framework of the design characteristics of exhibition space and the design elements of ecological architecture is obtained. The analysis results show that there are big changes between the temporary exhibition space and the permanent exhibition space in terms of building scale, space composition, function, materials and technology. On the one hand, the temporary exhibition space used recyclable materials, such as paper tubes, containers to be assembled on site into a single-layer space focused on display. The assembly method was simple and the construction period was short. After the exhibition, the exhibition space were dismantled. The materials were either transported to the next display site or recycled and reused. On the other hand, the permanent exhibition space used reinforced concrete as the main structure, and used a large amount of wood and glass materials to construct a multi-layered composite cultural space that separated the exhibition space and the leisure space. In terms of ecological characteristics, the building materials of the temporary exhibition space were recycled and no industrial wastes were generated after the demolition. The permanent exhibition hall uses eco-friendly wood for the roof and walls, so it is easy to replace and repair. Both types of exhibition halls are changing ecological architecture in a more sustainable direction by saving resources and energy through natural light and ventilation.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.21 no.6
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• pp.225-240
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• 2022

Gyeonggi-do comprises several types of areas, including urban, semi-urban, and rural areas. The availability of public transportation services varies depending on the area types, but the fare structure is based on a simple transfer rule, i.e., a transfer is free when completed within 30 minutes. As a result, users in non-urban areas with a poor frequency of public transportation services do not receive transfer discounts because most of the bus routes in these areas have a gap of more than 30 minutes between services. In terms of equality of opportunity, the transfer rule is being applied unfavorably and, as a result, equality of opportunity of the non-urban commuter is severely affected. Therefore, this study analyzed the user benefits mainly stemming from transfer fares using the smart card data of commuters using public transportation in Gyeonggi-do. An index called the beneficiary rate of the free transfer was developed and a scenario analysis was conducted based on the various levels of the rate. The results of this analysis proved that the users of public transportation services in non-urban areas in Gyeonggi-do can only receive transfer benefits by the extended time for free transfer and not by the implementation of a uniform policy irrespective of the type of area. The study also suggested an equitable fare transfer system and policy alternatives.