• Clean Technology
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• v.26 no.4
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• pp.329-335
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• 2020

Methanol synthesized from renewable hydrogen and captured CO2 has recently attracted great interest as a sustainable energy carrier for large-scale renewable energy storage. In this study, molten carbonate fuel cell's performance was investigated with the direct conversion of methanol into syngas inside the anode chamber of the cell. The internal reforming of methanol may significantly improve system efficiency since the heat generated from the electrochemical reaction can be used directly for the endothermic reforming reaction. The porous Ni-10 wt%Cr anode was sufficient for the methanol steam reforming reaction under the fuel cell operating condition. The direct supply of methanol into the anode chamber resulted in somewhat lower cell performance, especially at high current density. Recycling of the product gas into the anode gas inlet significantly improved the cell performance. The analysis based on material balance revealed that, with increasing current density and gas recycling ratio, the methanol steam reforming reaction rate likewise increased. A methanol conversion more significant than 90% was achieved with gas recycling. The results showed the feasibility of electricity and syngas co-production using the molten carbonate fuel cell. Further research is needed to optimize the fuel cell operating conditions for simultaneous production of electricity and syngas, considering both material and energy balances in the fuel cell.

• Journal of the Korean Association of Geographic Information Studies
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• v.24 no.1
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• pp.40-53
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• 2021

Research vessels(R/Vs) used for ocean research move to the planned research area and perform ocean observations suitable for the research purpose. The five research vessels of the Korea Institute of Ocean Science & Technology(KIOST) are equipped with global positioning system(GPS), water depth, weather, sea surface layer temperature and salinity measurement equipment that can be observed at all times during cruise. An information platform is required to systematically manage and utilize the data produced through such continuous observation equipment. Therefore, the data flow was defined through a series of business analysis ranging from the research vessel operation plan to observation during the operation of the research vessel, data collection, data processing, data storage, display and service. After creating a functional design for each stage of the business process, KIOST Underway Meteorological & Oceanographic Information System(KUMOS), a Web-Geographic information system (Web-GIS) based information platform, was built. Since the data produced during the cruise of the R/Vs have characteristics of temporal and spatial variability, a quality management system was developed that considered these variabilities. For the systematic management and service of data, the KUMOS integrated Database(DB) was established, and functions such as R/V tracking, data display, search and provision were implemented. The dataset provided by KUMOS consists of cruise report, raw data, Quality Control(QC) flagged data, filtered data, cruise track line data, and data report for each cruise of the R/V. The business processing procedure and system of KUMOS for each function developed through this study are expected to serve as a benchmark for domestic ocean-related institutions and universities that have research vessels capable of continuous observations during cruise.

• Composites Research
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• v.34 no.3
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• pp.192-198
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• 2021

Due to enormous market growing of electric vehicles without combustion engine, reducing unwanted BSR (buzz, squeak, and rattle) noise is highly demanded for vehicle quality and performance. Particularly, innerbelt weatherstrips which not only block wind noise, rain, and dust from outside, but also reduce noise and vibration of door glass and vehicle are required to exhibit high damping properties for improved BSR performance of the vehicle. Thermoplastic elastomers (TPEs), which can be recycled and have lighter weight than thermoset elastomers, are receiving much attention for weatherstrip material, but TPEs exhibit low material damping and compression set causing frictional noise and vibration between the door glass and the weatherstrip. In this study, high damping EPDM (ethylene-propylene-diene monomer)/PP (polypropylene) thermoplastic vulcanizates (TPV) were investigated by varying EPDM/PP ratio and ENB (ethylidene norbornene) fraction in EPDM. Viscoelastic properties of TPV materials were characterized by assuming that the material damping is directly related to the viscoelasticity. The optimum material damping factor (tanδ peak 0.611) was achieved with low PP ratio (14 wt%) and high ENB fraction (8.9 wt%), which was increased by 140% compared to the reference (tanδ 0.254). The improved damping is believed due to high fraction of flexible EPDM chains and higher interfacial slippage area of EPDM particles generated by increasing ENB fraction in EPDM. The stick-slip test was conducted to characterize frictional noise and vibration of the TPV weatherstrip. With improved TPV material damping, the acceleration peak of frictional vibration decreased by about 57.9%. This finding can not only improve BSR performance of electric vehicles by designing material damping of weatherstrips but also contribute to various structural applications such as urban air mobility or aircrafts, which require lightweight and high damping properties.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.66 no.4
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• pp.383-391
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• 2021

To develop a cultivation method for the mass production of sweetpotato cultivars, 'Juhwangmi' (orange tuber) and 'Sinjami' (puple tuber), the yield of tuber roots and content of various functional substances were analyzed according to planting intervals and growing periods. For 'Juhwangmi, the total yield of tubers was increased by respectively 36% and 54% and the yield of tubers over 300 g was increased by respectively 170% and 221% in the 140-day and 160-day cultivation plots compared with that in the 120-day cultivation plot at the 70×20 cm planting interval. Similarly, the total content of beta-carotene in the tubers increased as the cultivation period was extended. In particular, beta-carotene content at the 70×20 cm planting interval was the highest. For 'Sinjami', at the same planting interval, the total yield of tubers and yield of tubers over 300 g significantly increased as the growing period was extended. Within the same cultivation period, the yield of tubers over 300 g and the total anthocyanin content of 'Sinjami' were higher at the 70×30 and 70×35 cm planting intervals than at the 70×20 and 70×25 cm planting intervals in the 140-day and 160-day cultivation plots. Moreover, the total polyphenol and flavonoid content was significantly higher in 'Sinjami' than in 'Juhwangmi', and the values were the highest in the 160-day cultivation plots. In particular, the content of these two functional substances in tubers over 300 g was the highest at the 70×30 and 70×35 cm planting intervals.

• Geophysics and Geophysical Exploration
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• v.24 no.4
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• pp.194-201
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• 2021

Induced polarization (IP) effect is known to be caused by electrochemical phenomena at interface between minerals and pore water. Spectral induced polarization (SIP) method is an electrical survey to localize subsurface IP anomalies while injecting alternating currents of multiple frequencies into the ground. This method was effectively applied to mineral exploration of various ore deposits. Titanomagnetite ores were being produced by a mining company located in Gonamsan area, Gwanin-myeon, Pocheon-si, Gyeonggi-do, South Korea. Because the ores contain more than 0.4 w% vanadium, the ore deposit is called as Gwanin vanadiferous titanomagnetite (VTM) deposit. The vanadium is the most important of materials in production of vanadium redox flow batteries, which can be appropriately used for large-scale energy storage system. Systematic mineral exploration was conducted to identify presence of hidden VTM orebodies and estimate their potential resources. In geophysical exploration, laboratory geophysical measurement of rock samples is helpful to generate reliable property models from field survey data. Therefore, we performed laboratory SIP data of the rocks from the Gwanin VTM deposit to understand SIP characteristics between ores and host rocks and then demonstrate the applicability of this method for the mineral exploration. Both phase and resistivity spectra of the ores sampled from underground outcrop and drilling cores were different of those of the host rocks consisting of monzodiorite and quartz monzodiorite. Because the phase and resistivity at frequencies below 100 Hz are mainly dependent on the SIP characteristics of the rocks, we calculated mean values of the ores and the host rocks. The average phase values at 0.1 Hz were ores: -369 mrad and host rocks: -39 mrad. The average resistivity values at 0.1 Hz were ores: 16 Ωm and host rocks: 2,623 Ωm. Because the SIP characteristics of the ores were different of those of the host rocks, we considered that the SIP survey is effective for the mineral exploration in vanadiferous titanomagnetite deposits and the SIP characteristics are useful for interpreting field survey data.

• Journal of Practical Agriculture & Fisheries Research
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• v.22 no.1
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• pp.65-77
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• 2020

In order to industrialize of Dendranthema indicum (L.) DesMoul., which is a lot of commercially available and is synonymous with chrysanthemum tea, in the autumn of 2018, Dendranthema indicum (L.) DesMoul. seeds were collected from its own native region, and the seeds were germinated after refrigerated storage. Young seedlings were subjected to experiments in February, March, and April in the open field to examine the effects on the harvesting of leaves by distance and the growth of leaves and stems. The results of analyzing the components by collecting the leaves+stem after collecting the flower of Dendranthema indicum (L.) DesMoul. are as follows. 1. When D. indicum (L.) DesMoul. seedlings were planted according to the transplanting date, the number of flowers was 17.1 in the transplanting date in April. The diameter of the flower was 2.9cm, 16ea, 6.5~6.6g in the fresh weight, and the dry weight of the case was 1.1~1.2g. The leaves were 46~47ea in March and April in the planted area, 5.2~5.3cm in leaf length and 3.5~3.6cm in leaf width. 2. When planted D. indicum (L.) DesMoul. seedlings according to transplanting distance, the number of flowers was 16.2 when planted at 20×20cm intervals and, 16.8~17.1 at 30×30~50×50cm intervals. The diameter of the flower was 2.7~2.8cm, the number of petals was 8, the length of the petal was 0.8 cm, and fresh weight was 6.5~6.6g per flower. Leaves had the largest number of 47 of 30×30cm and 40×40cm, and leaf length appeared at the longest 6.2cm in the 50×50cm treatment area, but 5.2cm in the other treatment areas. 3. The extraction yield of D. indicum (L.) DesMoul. leaves+stems was 7.93%, and the extraction solvent colors were light green at 50, 60% and green at 70, 80, 90, 100%. The extraction yield of D. indicum (L.) DesMoul. flowers was 7.58%, the color of the extraction solvent was light yellow at 50, 60 and 70%, yellow at 80 and 90%, and dark yellow at 100%. 4. We confirmed 11 kinds of ingredients such as in D. indicum (L.) DesMoul. flowers are gallic acid, 4-hydroxy benzoic acid, methyl gallate, 4-hydroxy-3-methoxy benzoic, caffeic acid, salicylic acid, p-coumaric acid, sinapic acid, naringin, 4-melthoxyben, flavone. The content was 29.200-36.900ppm. 5. The components contained in the D. indicum (L.) DesMoul. leaf+stem, salicylic acid appeared at 6,129.526ppm, and the next 4-methoxyben was 1,966.714ppm. It was methyl gallate 8.197ppm, 4-hydroxy-3-methoxy benzoic 6.994ppm, caffeic acid 5.566ppm, flavone 4.522ppm, p-coumaric acid 3.787ppm, gallic acid 1.893ppm that appeared in the content below 10ppm.

• Journal of Life Science
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• v.32 no.7
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• pp.578-587
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• 2022

Korea, as the world's 7^th largest emitter of greenhouse gases, has raised the national greenhouse gas reduction target as international regulations have been strengthened. As it is possible to utilize coastal and marine ecosystems as important nature-based solutions (NbS) for implementing climate change mitigation or adaptation plans, the blue carbon ecosystem is now receiving attention. Blue carbon refers to carbon that is deposited and stored for a long period after carbon dioxide (CO₂) is absorbed as biomass by coastal ecosystems or oceanic ecosystems through photosynthesis. Currently, there are only three blue carbon ecosystems officially recognized by the Intergovernmental Panel on Climate Change (IPCC): mangroves, salt marshes, and seagrasses. However, the results of new research on the high CO₂ sequestration and storage capacity of various new blue carbon sinks, such as seaweeds, microalgae, coral reefs, and non-vegetated tidal flats, have been continuously reported to the academic community recently. The possibility of IPCC international accreditation is gradually increasing through scientific verification related to calculations. In this review, the current status and potential value of seaweeds, seagrass fields, and non-vegetated tidal flats, which are sources of blue carbon on the east coast, are discussed. This paper confirms that seaweed resources are the most effective NbS in the East Sea of Korea. In addition, we would like to suggest the direction of research and development (R&D) and utilization so that new blue carbon sinks can obtain international IPCC certification in the near future.

• Journal of Korea Port Economic Association
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• v.37 no.3
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• pp.117-128
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• 2021

In order for the users (shipping firms and shippers) and suppliers (stevedoring firms) in the container terminal industry to win-win, it is necessary to have some appropriate diverse market conditions for the industry. This study analyses the basic conditions and demand and supply characteristics of the industry and investigates the market performance of Busan container ports. First, this article analyses the basic characteristics of demand and supply. As the demand characteristics, there are five ones such as 1) exogeneity of demand, 2) function as export/import transportation and hub for transshipment, 3) increase of users' bargaining power, 4) high substituting elasticity, 5) reduction of volume growth. As the supply characteristics, there are seven ones such as 1) inelasticity of supply, 2) homogeneity of stevedoring services, 3) over-supply, 4) adoption of cutting-edge stevedoring technology, 5) scale economy and impossibility of storage, 6) labor market rigidity, 7) enhancing port's role in SCM. In addition, this study conducts the so-called structure-conduct-performance analysis. For the structure analysis, 1) lacks of scale economy in stevedoring companies, 2) high entry barrier, 3) strengthening of shipping firms' bargaining power, 4) transitory permission scheme for tariff are analyzed. For the conduct analysis, 1) price discrimination between export/import and transshipment, 2) mid-term length of terminal use contract, 3) continuous investment in equipment, 4) low level of cooperation among terminal operating firms are derived. For the performance analysis, 1) inequality in profitability, 2) reduction of export/import cost, 3) delay in adopting cutting-edge technology, 4) idle equipment are analyzed. Following this logical flow, the hypothesis that the market structure influences the market conduct is tested based on the actual dataset. As a future agenda in the conclusion, this article recommends the so-called port industrial policy.

• Korean Journal of Remote Sensing
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• v.38 no.5_3
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• pp.925-938
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• 2022

Agricultural reservoirs are an important water resource nationwide and vulnerable to abnormal climate effects such as drought caused by climate change. Therefore, it is required enhanced management for appropriate operation. Although water-level tracking is necessary through continuous monitoring, it is challenging to measure and observe on-site due to practical problems. This study presents an objective comparison between multiple AI models for water-body extraction using radar images that have the advantages of wide coverage, and frequent revisit time. The proposed methods in this study used Sentinel-1 Synthetic Aperture Radar (SAR) images, and unlike common methods of water extraction based on optical images, they are suitable for long-term monitoring because they are less affected by the weather conditions. We built four AI models such as Support Vector Machine (SVM), Random Forest (RF), Artificial Neural Network (ANN), and Automated Machine Learning (AutoML) using drone images, sentinel-1 SAR and DSM data. There are total of 22 reservoirs of less than 1 million tons for the study, including small and medium-sized reservoirs with an effective storage capacity of less than 300,000 tons. 45 images from 22 reservoirs were used for model training and verification, and the results show that the AutoML model was 0.01 to 0.03 better in the water Intersection over Union (IoU) than the other three models, with Accuracy=0.92 and mIoU=0.81 in a test. As the result, AutoML performed as well as the classical machine learning methods and it is expected that the applicability of the water-body extraction technique by AutoML to monitor reservoirs automatically.

• Korean Chemical Engineering Research
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• v.59 no.3
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• pp.345-358
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• 2021

This study focuses on the development of the liquid air production process that uses LNG (liquefied natural gas) cold energy which usually wasted during the regasification stage. The liquid air can be transported to the LNG exporter, and it can be utilized as the cold source to replace certain amount of refrigerant for the natural gas liquefaction. Therefore, the condition of the liquid air has to satisfy the available pressure of LNG storage tank. To satisfy pressure constraint of the membrane type LNG tank, proposed process is designed to produce liquid air at 1.3bar. In proposed process, the air is precooled by heat exchange with LNG and subcooled by nitrogen refrigeration cycle. When the amount of transported liquid air is as large as the capacity of the LNG carrier, it could be economical in terms of the transportation cost. In addition, larger liquid air can give more cold energy that can be used in natural gas liquefaction plant. To analyze the effect of the liquid air production amount, under the same LNG supply condition, the proposed process is simulated under 3 different air flow rate: 0.50 kg/s, 0.75 kg/s, 1.00 kg/s, correspond to Case1, Case2, and Case3, respectively. Each case was analyzed thermodynamically and economically. It shows a tendency that the more liquid air production, the more energy demanded per same mass of product as Case3 is 0.18kWh higher than Base case. In consequence the production cost per 1 kg liquid air in Case3 was $0.0172 higher. However, as liquid air production increases, the transportation cost per 1 kg liquid air has reduced by $0.0395. In terms of overall cost, Case 3 confirmed that liquid air can be produced and transported with $0.0223 less per kilogram than Base case.