• Journal of Apiculture
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• v.34 no.3
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• pp.245-254
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• 2019

We investigated the anti-tumor effects and molecular mechanism of Brazil, China and Korean regional propolis on HeLa ovarian cancer cell line. Each propolis extracts was prepared by ethanol extraction method. Cytotoxicity of propolis extracts was determinated by EZ-cytox cell viability assay. To necessity of anti-tumor effect and molecular mechanism of propolis, we must be adjusting propolis concentration. Due to 100 ㎍/mL of propolis extract were reduced cell viability to less than 50%, we adjusted all of propolis concentration to 100 ㎍/mL. By Western blotting analysis, we confirmed that anti-tumor mechanism of Brazil, China and Korea regional propolis has significantly difference. All of propolis was activated apoptosis related molecules such as PARP, caspase-3. However, cell proliferation signaling molecules including Akt1, ERK and Bcl-2 were reduced the protein expression level. Especially, the expression of tumor suppressor protein p53 was significantly increased in propolis-treated group such as Gyeonggi, Chungbuk, Chungnam, Jeonbuk, Gyeongnam and China. The phosphorylation of Bax which as apoptosis indicator was appeared in propolis-treated group such as Gyeonggi, Gangwon, Chungnam, Gyeongbuk, China. In this results showed that the regional propolis has completely different mechanism in anti-tumor. Thus, propolis extracts may be useful source of functional materials on anti-cancer and it will be able to choose the suitable propolis for cancer therapy by analyzing individual characteristics.

• Ecology and Resilient Infrastructure
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• v.9 no.1
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• pp.77-82
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• 2022

This study aims to understand how mobile and stationary air pollution sources affect the air quality and soil properties in urban parks. We selected three sites of urban parks in Seoul as follows: Ha-neul Park in Mapo-gu (Site_M), Ill-won Eco-Park in Gangnam-gu (Site_G), and Yangjae Citizen's Forest in Seocho-gu (Site_Y), and compared the results of each site's traffic volume, air quality concentration, and soil analysis. Traffic volume was high in Site_M, followed by Site_G and Y; Site_M and G were closer to the resource recovery facility than Site_Y. Hence, we hypothesized that PM and NO₂ concentrations in the atmosphere were higher in Site_M than Site_G and Y, causing different soil nitrogen content among sites due to different atmospheric deposition. Consistent with our hypothesis, the concentrations of PM2.5 and NO₂ were higher in Site_M and G than Site_Y, while Site_Y had higher PM10 than other sites. The soil NO₃^- contents showed no significant difference among three sites, whereas the soil NH₄+ content was extremely high in Site_Y. This high content of soil NH₄⁺ is thought to be due to acidification from excessive fertilization. Lower soil pH of Site_Y further supported the evidence of heavy fertilization in this site. Overall nitrogen dynamics implies that soil nitrogen status is more influenced by park management such as fertilization rather than atmospheric deposition. Despite of lower soil NH₄⁺ content of Site_M and G than Y, vegetation vitality looked similar among three sites. This indirectly indicates that excessive fertilizer input in urban park management needs to be reconsidered. This study showed that even if the air quality was different due to mobile and stationary sources, it did not directly affect the soil nitrogen nutrient status of the adjacent urban park.

• 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.

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.1
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• pp.1-9
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• 2022

The effect of sediments in a waste dumping area on marine organisms was evaluated using sediment toxicity tests with a benthic amphipod (Monocorophium acherusicum) and bioluminescent bacterium (Vibrio fischeri) in accordance with the Korean Standard Method for Marine Wastes (KSMMW). Nine sites in the East Sea-Byeong, East Sea-Jeong, and Yellow Sea-Byeong areas were sampled from 2016 to 2019. The test results showed that the relative average survival rate (benthic amphipods) and relative luminescence inhibition rate (luminescent bacteria) were below 30%, which were judged to be "non-toxic." However, in the t-test, a total of 12 benthic amphipod samples (6, 1, 1, and 4 in 2016, 2017, 2018, and 2019, respectively) were significantly different (p<0.05) from the control samples. To identify the source of toxicity on benthic amphipods, a simple linear regression analysis was performed between the levels of eight heavy metals (Cr, As, Ni, Cd, Cu, Pb, Zn, and Hg) in sediments and the relative average survival rate. The results indicated that Cr had the highest contribution to the toxicity of benthic amphipods (p = 0.000, R2 = 0.355). In addition, Cr was detected at the highest concentration at the DB-85 station and exceeded the Marine Environment Standards every year. Although the sediments were determined as "not toxic" according to the ecotoxicity criteria of the KSMMW, the results of the statistical significance tests and toxicity identification evaluation indicated that the toxic effect was not acceptable. Therefore, revising the criteria for determining the toxic effect by deriving a reference value through quantitative risk assessment using species sensitivity distribution curves is necessary in the future.

• Journal of the Korean Society of Radiology
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• v.17 no.1
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• pp.149-156
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• 2023

The purpose of this study is to compare of growth and chlorophyl between old-barley seed (OBS, 2019) and New-barley seed (NBS, 2020) exposed by X-ray. After germination the OBS and NBS, experimental group was exposed by 30 Gy X-ray using linear accelerator (Clinac IS, VERIAN, USA), by 6 MV X-ray, SSD 100 cm, 18 × 10 cm², 600 MU/min. Length was measured every day until 9th day, and chlorophyl was analyzed using spectrophotometer(uv-1800, shimadzu, japan) after measuring weight in 9th day. Data analysis was performed the Independent T-test using SPSS ver 26.0(Chicago, IL, USA). NBS grow more faster than OBS in control group, but OBS grow more faster than NBS in experimental group. Length of control group was longer significantly every day than that of experimental group in OBS. NBS weighted more than OBS in control group, but OBS weighted more than NBS in experimental group. In comparing chlorophyl density, NBS high more than OBS in control group as well as experimental group. Growth and weight of OBS was effected more those than NBS by X-ray, but NBS in chlorophyl by X-ray. It is expected to be used as basic data for future X-ray research in barley seed.

• Ecology and Resilient Infrastructure
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• v.9 no.1
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• pp.1-14
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• 2022

The total maximum daily load (TMDL) implemented in Korea mainly manages the mainstream considering a single common pollutant and river discharge, and the river system is divided into unit watersheds. Changes in the water quality of managed rivers owing to the water quality management in tributaries and unit watersheds are not considered when implementing the TMDL. In addition, it is difficult to consider the difference in the load of pollutants generated in the tributary depending on the conditions of the water quality change in each unit watershed, even if the target water quality was maintained in the managed water system. Therefore, it is necessary to introduce the total maximum load management at tributaries to manage the pollution load of tributaries with a high degree of pollution. In this study, the HSPF model, a watershed runoff model, was applied to the target areas consisting of 53 sub-watersheds to analyze the effect of water quality changes the in tributaries on the mainstream. Sub-watersheds were selected from the three major areas of the Paldang water system, including the drainage basins of the downstream of the South Han-River, Gyeongan stream, and North Han-River. As a result, BOD ranged from 0.17 mg/L to 4.30 mg/L, and was generally high in tributaries and decreased in the downstream watershed. TP ranged from 0.02 mg/L - 0.22 mg/L, and the watersheds that had a large impact on urbanization and livestock industry were high, and the North Han-River basin was generally low. In addition, a pollution source reduction scenario was selected to analyze the change in water quality by the amount of pollution load discharged at each unit watershed. The reduction rate of BOD and TP according to the scenario changes was simulated higher in the watershed of the downstream of the North Han-River and downstream and midstream of the Gyeongan stream. It was found that the benefits of water quality reduction from each sub-watershed efforts to improve water quality are greatest in the middle and downstream of each main stream, and it is judged that it can be served as basic data for the management of total tributaries.

• Journal of Korean Elementary Science Education
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• v.41 no.2
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• pp.283-294
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• 2022

Although the concept of light is important in the elementary school curriculum, substantial research suggests that students and teachers have difficulties in understanding it. Therefore, it is necessary to analyze the reasons for these difficulties-whether it is due to the content or due to the presentation method of contents, structure, and expression. The national curriculum and textbooks of Korea, the US, China, and Japan were comparatively analyzed from the following perspectives: 1) key concepts of light, 2) structure of light units in the textbook, 3) materials, light sources, and optics used in light units. Consequently, there were differences between countries in their inclusion of the concept of light in the curriculum. In particular, the Korean curriculum studies the concept of refraction by a convex lens, whereas the concept of light, light source, and vision is not introduced. Furthermore, countries also differed in their structuring of units. The Korean curriculum was presented segmentally by concept rather than structured according to core ideas or perspectives, and the connection between concepts was unclear. In addition, there were differences between the countries in materials, light sources, and optical instruments to explain key concepts. On using light, the US curriculum provides a purpose and uses light to achieve it, and China and Korea understand the concept. It was divided into the method of using the material to deepen. Based on the results of this analysis, the implications for the elementary science curriculum in Korea were derived as follows. First, it is necessary to introduce concepts sequentially and organize them so that the connection between concepts is well expressed. Second, it is necessary to introduce light and light sources as the predominant concepts. Third, it is necessary to include the principle of seeing objects. Fourth, it is necessary to adjust the material and content level of the refraction concept included in the light and lens unit. Fifth, an integrated approach is required because light has a deep connection with various concepts included in the elementary science curriculum.

• Environmental and Resource Economics Review
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• v.31 no.2
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• pp.165-204
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• 2022

This study organized data from 2000 to 2014 for 20 grid-connected countries in Europe and analyzed the determinants of carbon emissions through the panel GLS method considering the problem of heteroscedasticity and autocorrelation. At the same time, the effect of introducing ETS was considered by dividing the sample period as of 2005 when the European emission trading system was introduced. Carbon emissions from individual countries were used as dependent variables, and proportion of generation by each source, power self-sufficiency ratio of neighboring countries, power production from resource-holding countries, concentration of power sources, total energy consumption per capita in the industrial sector, tax of electricity, net electricity export per capita, and size of national territory per capita. According to the estimation results, the proportion of nuclear power and renewable energy generation, concentration of power sources, and size of the national territory area per capita had a negative (-) effect on carbon emissions both before and after 2005. On the other hand, the proportion of coal power generation, the power supply and demand rate of neighboring countries, the power production of resource-holding countries, and the total energy consumption per capita in the industrial sector were found to have a positive (+) effect on carbon emissions. In addition, the proportion of gas generation had a negative (-) effect on carbon emissions, and tax of electricity were found to have a positive (+) effect. However, all of these were only significant before 2005. It was found that net electricity export per capita had a negative (-) effect on carbon emissions only after 2005. The results of this study suggest macroscopic strategies to reduce carbon emissions to green growth, suggesting mid- to long-term power mix optimization measures considering the electricity trade market and their role.

• Journal of Service Research and Studies
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• v.12 no.2
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• pp.135-151
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• 2022

This study was conducted on a servicism basis as a study to build the management wisdom of Korea as an asset of human society. The case of the founding and development of the Republic of Korea, which developed into one of the world's leading powers with unprecedented rapid growth despite the devastating three-year war immediately after its founding, is an important subject of study. This study conducted a macroscopic analysis. In the process of carrying out the founding activities, it was confirmed that the original idea inherent in Koreans was the Taegeuk idea of the National Flag. The founders of the Republic of Korea consciously or unconsciously adopted the Taegeuk ideology as the founding ideology. It can be said that the Taegeuk ideology has led to greater success because it is based on the service philosophy, which is the common truth of mankind. In this study, the process of preparing for the founding of the Republic of Korea, which was founded by accepting a new maritime civilization from a country with a long continental civilization, the process of national foundation, and the process of operating the country after its founding were analyzed as a whole. In particular, it discovered the excellent wisdom of the founders who appropriately utilized the strengths of continental and maritime civilizations in necessary situations, and confirmed that the dynamic operating model of development through fierce competition between the two opponents was a success factor for high-speed national development. It requires great wisdom for Koreans with diverse ideological backgrounds and unique personalities to unite to establish and run a nation. This is because fierce competition and cooperation must be carried out at the same time. The great wisdom of the founding of the Republic of Korea was able to be demonstrated because the Taegeuk ideology was acting as a common basic ideology for Koreans. Taegeuk ideology, the source of wisdom that Korea has developed under constant tension, can be capitalized as human wisdom, and additional case studies are needed.

• Journal of The Korean Association For Science Education
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• v.43 no.3
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• pp.253-263
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• 2023

This study explored the discrepancy between the text of a teacher's guide about straight and reflective light and the content knowledge of pre-service elementary teachers. A total of 455 questions and 543 answers generated by 279 pre-service elementary teachers after reading a 'Shadow and Mirror' unit in the teacher's guide were analyzed. The questions were classified according to the types of concepts and discrepancies, and the answers were analyzed for accuracy. The results of analyzing the concepts of questions revealed that the pre-service elementary teachers were most curious about the shadow in the straight concept, the mirror image in the reflection concept, and the light source in other concepts. The questions with a low correct answer rate due to incorrect- or non-answers, such as those concerning the superposition principle of light by reflection, the principle of experimental tools, and images by lenses, were only partially or not included in the teacher's guide. When the questions were classified according to the type of discrepancy, the frequency of questions due to knowledge deficit was higher than that due to knowledge clash. This demonstrates that the concepts that teachers need to know must be supplemented with the contents of the teacher's guide. Discrepancies due to knowledge clashes are often caused by conflicts between what is experienced in everyday life and what is presented in textbooks. Therefore, it is necessary to reduce the discrepancy between the texts of the teacher's guide and the knowledge of pre-service elementary teachers by including the differences between the actual context of everyday life and the context of the textbook in the teacher's guide.