• Economic and Environmental Geology
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• v.55 no.3
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• pp.241-259
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• 2022

In general, the REE were produced by mining conventional deposits, such as the carbonatite or the clay-hosted REE deposits. However, because of the recent demand increase for REE in modern industries, unconventional REE deposits emerged as a necessary research topic. Among the unconventional REE recovery methods, the REE-bearing coal deposits are recently receiving attentions. R-types generally have detrital originations from the bauxite deposits, and show LREE enriched REE patterns. Tuffaceous-types are formed by syngenetic volcanic activities and following input of volcanic ash into the basin. This type shows specific occurrence of the detrital volcanic ash-driven minerals and the authigenic phosphorous minerals focused at narrow horizon between coal seams and tonstein layers. REE patterns of tuffaceous-types show flat shape in general. Hydrothermal-types can be formed by epigenetic inflow of REE originated from granitic intrusions. Occurrence of the authigenic halogen-bearing phosphorous minerals and the water-bearing minerals are the specific characteristics of this type. They generally show HREE enriched REE patterns. Each type of REE-bearing coal deposits may occur by independent genesis, but most of REE-bearing coal deposits with high REE concentrations have multiple genesis. For the case of the US, the rare earth oxides (REO) with high purity has been produced from REE-bearing coals and their byproducts in pilot plants from 2018. Their goal is to supply about 7% of national REE demand. For the coal deposits in Korea, lignite layers found in Gyungju-Yeongil coal fields shows coexistence of tuff layers and coal seams. They are also based in Tertiary basins, and low affection from compaction and coalification might resulted into high-REE tuffaceous-type coal deposits. Thus, detailed geologic researches and explorations for domestic coal deposits are required.

• Clean Technology
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• v.28 no.4
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• pp.269-277
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• 2022

With the recent development of the biological enzymatic reaction industry, lactic acid (LA) can be mass-produced from biomass sources. In particular, a catalytic process that converts LA into acrylic acid (AA) is receiving much attention because AA is used widely in the petrochemical industry as a monomer for superabsorbent polymers (SAP) and as an adhesive for displays. In the LA conversion process, NaY zeolites have been previously shown to be a high-activity catalyst, which improves AA selectivity and long-term stability. However, NaY zeolites suffer from fast deactivation due to severe coking. Therefore, the aim of this study is to modify the acid-base properties of the NaY zeolite to address this shortcoming. First, base promoters, Ca ions, were introduced to the NaY zeolites to tune their acidity and basicity via ion exchange (IE) and incipient wetness impregnation (IWI). The IWI method showed superior catalyst selectivity and stability compared to the IE method, maintaining a high AA yield of approximately 40% during the 16 h reaction. Based on the NH₃- and CO₂-TPD results, the calcium salts that impregnated into the NaY zeolites were proposed to exit as an oxide form mainly at the exterior surface of NaY and act as additional base sites to promote the dehydration of LA to AA. The NaY zeolites were further treated with KOH before calcium impregnation to reduce the total acidity and improve the dispersion of calcium through the mesopores formed by KOH-induced desilication. However, this KOH treatment did not lead to enhanced AA selectivity. Finally, calcium loading was increased from 1wt% to 5wt% to maximize the amount of base sites. The increased basicity improved the AA selectivity substantially to 65% at 100% conversion while maintaining high activity during a 24 h reaction. Our results suggest that controlling the basicity of the catalyst is key to obtaining high AA selectivity and high catalyst stability.

• KIPS Transactions on Software and Data Engineering
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• v.12 no.1
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• pp.19-30
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• 2023

An electric scooter(e-scooter), one popularized micro-mobility vehicle has shown rapidly increasing use in many cities. In South Korea, the use of e-scooters has greatly increased, as some companies have launched e-scooter sharing services in a few large cities, starting with Seoul in 2018. However, the use of e-scooters is still controversial because of issues such as parking and safety. Since the perception toward the means of transportation affects the mode choice, it is necessary to track the trends for electric scooters to make the use of e-scooters more active. Hence, this study aimed to analyze the trends related to e-scooters. For this purpose, we analyzed news articles related to e-scooters published from 2014 to 2020 using dynamic topic modeling to extract issues and sentiment analysis to investigate how the degree of positive and negative opinions in news articles had changed. As a result of topic modeling, it was possible to extract three different topics related to micro-mobility technologies, shared e-scooter services, and regulations for micro-mobility, and the proportion of the topic for regulations for micro-mobility increased as shared e-scooter services increased in recent years. In addition, the top positive words included quick, enjoyable, and easy, whereas the top negative words included threat, complaint, and ilegal, which implies that people satisfied with the convenience of e-scooter or e-scooter sharing services, but safety and parking issues should be addressed for micro-mobility services to become more active. In conclusion, this study was able to understand how issues and social trends related to e-scooters have changed, and to determine the issues that need to be addressed. Moreover, it is expected that the research framework using dynamic topic modeling and sentiment analysis will be helpful in determining social trends on various areas.

• Land and Housing Review
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• v.13 no.2
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• pp.49-64
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• 2022

To effectively lead "Innovative City Season 2", it is important to investigate whether the creation of an innovative city has a positive effect on the revitalization of the hinterland town economy. This study explores the effects (external effects) of increases in the number of workers at public institutions in the innovative city of Jeollabuk-do, located closest to the hinterland town (Jeonju-si). In the results, we show that increases in the number of workers positively affected the commercial real estate market, which is one of the barometers that show the revitalization level. On the other hand, the effect was found to be limited to the new downtown commercial real estate market with good accessibility and modernized facilities and services. This suggests that the innovative city adjacent to the hinterland town meets the purpose of the innovative city to some extent by generating a positive external effect, especially in accessible and modernized areas. To further expand the positive spillover effects of an innovative city on the hinterland town, it is necessary to expand public institutions for relocation, improve settlement conditions, and establish a practical cooperation system between specialized public institutions and hinterland-related industries.

• Journal of Bio-Environment Control
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• v.31 no.2
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• pp.133-141
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• 2022

Bulbophyllum auricomum Lindl. is a rare orchid and has flowers with an attractive fragrance. The present study investigated the tissue culture method for micropropagation. Capsules derived from artificial self-pollination were obtained for the best seed germination in MS basal medium. Plant growth regulators (1.0 mg·L^-1 of BAP and 2.0 mg·L^-1 of NAA) were affected by callus induction from subcultured pseudobulb explants. For the callus subculture, different natural plant extracts were tested in 11 treatment media. Among them, MS medium with 150 mL·L^-1 of coconut water was generally effective in fresh weight (1.75 ± 0.08) and (3.01 ± 0.20) of callus proliferation and PLBs induction at 1 and 2 months, respectively, followed by an MS combination of 30 g·L^-1 of banana and 20 g·L^-1 of potato extract. The results of a comparative study of different MS mediums containing plant growth regulators with a natural extract combination and MS medium supplemented with natural extract only showed that MS medium supplemented with a combination of natural extracts (150 mL·L^-1 of coconut water) and plant growth regulators (2.0 mg·L^-1 of BAP and 1.0 mg·L^-1 of NAA) obtained the highest shoot regeneration (3.37 ± 0.17) and (6.41 ± 0.68) after 1 month and 2 months of culturing, respectively.

• Journal of Environmental Impact Assessment
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• v.32 no.1
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• pp.49-59
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• 2023

The rapid advance of technology has accelerated global warming. As 50.4 percent of South Korea's population is concentrated in the Seoul Metropolitan Area, which has become a considerable emitter of greenhouse gases, the city's average temperature is expected to increase more rapidly than in other areas in the country. A rise in the average temperature would affect everyday life and urban ecology; thus, appropriate measures to cope with the forthcoming disaster are in need. This study analyzed the changes in plant phenological phases from the past to the present based on temperatures (average temperature of Feb, Mar, April) observed in seven different weather stations nearthe Seoul Metropolitan Area (Ganghwa, Seoul, Suwon, Yangpyeong, Icheon, Incheon, and Paju) and the first flowering dates of Plum tree (Prunus mume), Korean forsythia (Forsythia koreana), Korean rosebay (Rhododendron mucronulatum), Cherry tree (Prunus serrulate), Peach tree (Prunus persica), and Pear tree (Pyrus serotina). Then, RCP (Representative Concentration Pathways) 2.6 and 8.5 scenarios were used to predict the future temperature in the Seoul Metropolitan Area and how it will affect plant phenological phases. Furthermore, the study examined the differences in the flowering dates depending on various strategies to mitigate greenhouse gases. The result showed that the rate of plant phenological change had been accelerated since the 1900s.If emission levels remain unchanged, plants will flower from 18 to 29 earlier than they do now in the Seoul Metropolitan Area, which would be faster than in other areas in the country. This is because the FFD (First Flowering Date), is highly related to temperature changes. The Seoul Metropolitan Area, which has been urbanized more rapidly than any other areas, is predicted to become a temperature warming, forcing the FFDs of the area to occur faster than in the rest of the country. Changes in phenology can lead to ecosystem disruption by causing mismatches in species interacting with each otherin an ecosystem. Therefore, it is necessary to establish strategies against temperature warming and FFD change due to urbanization.

• Composites Research
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• v.36 no.1
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• pp.1-15
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• 2023

Demand for energy consumption reduction is increasing according to the development expectations of future mobility. Lightweight structural materials are known as a method to reduce greenhouse gas emissions and improve energy efficiency. In particular, fiber reinforced polymer composite (FRP) is attracting attention as a material that can replace existing metal alloys due to its excellent mechanical properties and light weight. In this paper, industrial applications and research trends of carbon fiber reinforced composites (CFRP, carbon FRP) and self-reinforced composites (SRC) were reviewed based on the reinforcement, polymer matrix, and manufacturing process. In order to overcome the expensive process cost and long manufacturing time of the epoxy resin-based autoclave method, which is mainly used in the aircraft field, mass production of CFRP-applied electric vehicles has been reported using a high-pressure resin transfer molding process including fast-curing epoxy. In addition, thermoplastic resin-based CFRP and interface enhancement methods to solve the recycling issue of carbon fiber composites were reviewed in terms of materials and processes. To form a perfect matrix-reinforcement interface, which is known as the major factor inducing the excellent mechanical properties of FRP, studies on SRC impregnated with the same matrix in polymer fibers have been reported. The physical and mechanical properties of SRC based on various thermoplastic polymers were reviewed in terms of polymer orientation and composite structure. In addition, a copolymer matrix strategy for extending the processing window of highly drawn polypropylene fiber-based SRC was discussed. The application of CFRP and SRC as lightweight structural materials can provide potential options for improving the energy efficiency of future mobility.

• Economic and Environmental Geology
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• v.56 no.4
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• pp.457-473
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• 2023

Asbestos has been produced, imported and used in various industries in Korea over the past decades. Since asbestos causes fatal diseases such as malignant mesothelioma and lung cancer, the use of asbestos has been generally banned in Korea since 2009. However, there are still many asbestos-containing materials around us, and safe management is urgently needed. This study aims to examine asbestos-related trend changes using major asbestos-related keywords based on the asbestos trend analysis using big data for the past 32 years (1991 to 2022) in Korea. In addition, we reviewed both domestic trends related to the production, import, and use of asbestos before 1990 and asbestos-related policies from 2023 to 2027. From 1991 to 2000, main keywords related to asbestos were research, workers, carcinogens, and the environment because the carcinogenicity of asbestos was highlighted due to domestic production, import, and use of asbestos. From 2001 to 2010, the main keywords related to asbestos were lung cancer, litigation, carcinogens, exposure, and companies because lawsuits were initiated in the US and Japan in relation to carcinogenicity due to asbestos. From 2011 to 2020, the high ranking keywords related to asbestos were carcinogen, baseball field, school, slate, building, and abandoned asbestos mine due to the seriousness of the asbestos problem in Korea. From 2021 to present (2023), the main search keywords related to asbestos such as school, slate (asbestos cement), buildings, landscape stone, environmental impact assessment, apartment, and cement appeared.

• (The) Research of the performance art and culture
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• no.40
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• pp.193-222
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• 2020

In this study, the development of traditional contents is to be enabled to succeed the values of the heritage on the song sang during dry-field farming of Bongpyeong Memil-dorikkaejil-sori. In addition, the identity on the heritage of songs sang during farming were diagnosed, and their value in context with the history and the value as the community for succession are emphasized as the value of cultural asset to expand the discussion up to the level of traditional cultural industry works. In the Bongpyeong Memil-dorikkaejil-sori, the intrinsic artistic value, the excellence of value as the educational experience, factor for overcoming the extinction of farming songs, and the promotion direction of the storytelling on buckwheat were provided. This is breaking from the formalization and being old-fashioned on the Bongpyeong Memil-dorikkaejil-sori to focus on the symbolization of the agricultural heritage in the modern context, habituating and spreading the gene of slash-and-burn field (hwajeon or budaeki). In terms of methodology on awareness, historicity or creativity, alternative method on the folk songs in labor was provided by having critical mind on the Bongpyeong Memil-dorikkaejil-sori and buckwheat songs. By reviewing the field contextualization of designating the intangible cultural asset, suggestions were made on activating the succession, and even the method of symbolic registration on the heritage of buckwheat farming was mentioned. Heritage on agricultural culture that can represent Pyeongchang and Gangwon must be discovered to be made into a brand. In addition, the uniqueness in the Madang 'Song Madaengi Traditional Music' must be found to apply as the brand on the point in which the people around the world can have consensus for utilization. As the farming song, rediscovery of the Bongpyeong Memil-dorikkaejil-sori is required to create the sustainable status as the multi-purpose cultural contents and provide the network of professionals for activating the folk songs to enable the opportunity of qualitative substantiality and spread instead of quantitative growth. In addition, festivals for each region, especially the festival for Pyeongchang area must be utilized centrally on the development of farming songs to organize the storytelling actively.

• Research in Plant Disease
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• v.28 no.4
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• pp.221-230
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• 2022

The fire blight caused by Erwinia amylovora (Ea) was first reported in 2015 in Korea, and the disease has rapidly spread to 22 regions until 2021. In Korea, all host plants in the apple and pear orchards where fire blight occurred should be eliminated and buried by the Plant Protection Act. To prevent the spread of the disease, all burial sites were prohibited from planting the new host plants for the next three years. To confirm the eradication efficiency of Ea and the reoccurrence of fire blight, the surveillance facilities were established on three burial sites from 2019 to 2020 in Anseong-si, Gyeonggi-do, and Chungju-si, Chungcheongbuk-do. As host plants, five apple trees of fire blight-susceptible cultivar 'Fuji', were planted in each facility. All facilities were enclosed with fences and nets and equipped with two CCTVs, motion sensors, and several other sensors for recording weather conditions to monitor the environment of the sentinel plants in real-time. The sentinel plants were checked for the reoccurrence of fire blight routinely. Suspicious plant parts were collected and analyzed for Ea detection by loop-mediated isothermal amplification polymerase chain reaction and conventional polymerase chain reaction. Until November 2022, Ea has not been detected in all sentinel plants. These results might support that the burial control of infected plants in soil works efficiently to remove Ea and support the possibility to shorten the prohibition period of host plant establishment in the burial sites.