• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.32 no.5
• /
• pp.333-340
• /
• 2019

Tests using a middle velocity propulsion impact machine (MVPIM) were performed to verify the impact resistance capability of sandwich concrete panels (SCP) in a modular liquefied natural gas (LNG) outer tank, and numerical models were constructed and analyzed. $2{\times}2m$ specimens with plain sectional characteristics and specimens including a joint section were used. A 51 kg missile was accelerated above 45 m/s and impacted to have the design code kinetic energy. Impact tests were performed twice according to the design code and once for the doubled impact speed. The numerical models for simulating impact behaviors were created by LS-DYNA. The external steel plate and filled concrete of the panel were modeled as solid elements, the studs as beam elements, and the steel plates as elasto-plastic material with fractures; the CSCM material model was used for concrete. The front plate deformations demonstrated good agreement with those of other tests. However the rear plate deformations were less. In the doubled speed test for the plain section specimen, the missile punctured both plates; however, the front plate was only fractured in the numerical analysis. The impact energy of the missile was transferred to the filled concrete in the numerical analysis.

• Korean Journal of Heritage: History & Science
• /
• v.48 no.4
• /
• pp.138-153
• /
• 2015

A Jincheon Seokjangri B23 furnace was reconstructed and iron smelting experiment was performed to investigate an ancient Baekjae iron production process. The work mainly described in this paper is the $1^{st}$ and $2^{nd}$ experiments among the several experiments carried out at Jungwon National Research Institute of Cultural Heritage. Iron ore(magnetite) and oak charcoal were used as a source and a foot bellow was used for air supply. Common results of the experiments are masses of iron, slag and charcoal formed in the furnace. Most iron lumps were formed nearby the tuyere rather than the area of tapping hole. Metallographic and chemical analysis shows that the iron lumps can be used for either forge or cast depending on their carbon content. Low Fe content and glassy texture of the inner slags suggest that the operation environment was quite reducing. Based on the results of the iron smelting experiments, measurements and analysis, various information was obtained regarding physical-chemical and metallurgical processes of the ancient iron smelting process. It is firmly believed that its undisclosed contents can be revealed more in depth with continual reconstitution experiments.

• Journal of Wetlands Research
• /
• v.23 no.1
• /
• pp.60-66
• /
• 2021

As the concentration of nitrogen in the sewage flowing into the sewage treatment plant increases due to urbanization and industrialization, the degree of adverse effects such as eutrophication and toxicity to the aquatic ecosystem is also increasing. In order to treat sewage containing high concentration of nitrogen, various studies on the biological nitrogen removal process are being conducted. Existing biological nitrogen removal processes require significant costs for supplying oxygen and supplementing external carbon sources. In this respect, as a high-level nitrogen removal process with economic improvement is required, an anaerobic ammonium oxidation process (ANAMMOX), which is more efficient and economical than the existing nitrification and denitrification processes, has been proposed. The purpose of this study is to confirm the stability of the ANAMMOX process in the water treatment process and to derive the ratio of ammonia nitrogen (NH4+) to nitrite nitrogen (NO2-) for the implementation of the mainstream ANAMMOX process. A laboratory-scale Mainstream ANAMMOX reactor was operated by applying the ratio calculated based on the substrate ratio suggested in the previous study. In the initial range, the removal efficiency of NH4+ was 58~86%, and the average removal efficiency was 70%. In the advanced range, the removal efficiency of NH4+ was 94~99%, and the average removal efficiency was 95%. As a result of the study, as the NH4+/NO2- ratio increased, the stability of the mainstream ANAMMOX process was secured, and it was confirmed that the NH4+ removal efficiency and the total nitrogen (TN) removal efficiency increased. As a result, the results of this study are expected to be used as basic data in the application of the ANAMMOX process in the mainstream.

• Korean Journal of Environment and Ecology
• /
• v.36 no.5
• /
• pp.507-524
• /
• 2022

In this study, we revealed the location environment and community structural characteristics after extensively investigating Korea's warm-temperate island areas and categorizing vegetation through TWINSPAN analysis. Based on it, this study aims to suggest the direction of the vegetation restoration plan for warm-temperate forests by deriving a restoration strategy for each vegetation type. The vegetation types were clearly divided into eight types, and communities I through IV were good evergreen broad-leaved forests dominated by Machilus thunbergii and Castanopsis sieboldii. On the other hand, communities V through VIII were Pinus thunbergii forest, deciduous broad-leaved forest, and artificial forest, and retrogressive succession vegetation in the warm-temperate areas. The environmental factors derived from the DCA analysis were altitude (average temperature of the coldest month) and distance from the coastline (salt tolerance). The distribution pattern of warm-temperate forests has been categorized into M. thunbergii, C. sieboldii and Cyclobalanopsis spp. forest types according to the two environmental factors. It is reasonable to apply the three vegetation types as restoration target vegetation considering the location environment of the restoration target site. In communities V through VIII, P. thunbergiiand deciduous broad-leaved formed a canopy layer, and evergreen broad-leaved species with strong seed expansion frequently appeared in the ground layer, raising the possibility of vegetation succession as evergreen broad-leaved forests. The devastated land where forests have disappeared in the island areas is narrow, but vegetation such as P. thunbergii and deciduous broad-leaved forests, which have become a retrogressive succession, forms a large area. The restoration strategy of renewing this area into evergreen, broad-leaved forests should be more effective in realizing carbon neutrality and promoting biodiversity.

• Journal of Nutrition and Health
• /
• v.55 no.3
• /
• pp.330-347
• /
• 2022

Folate, a water-soluble vitamin, acts as a coenzyme for one-carbon metabolism in nucleic acid synthesis and amino acid metabolism. Adequate folate nutritional status during the periconceptional period is known to prevent neural tube defects. In addition, insufficient folate intake is associated with various conditions, such as anemia, hyperhomocysteinemia, cardiovascular disease, cancer, cognitive impairment, and depression. This review discusses the rationale for the revision of the 2020 Korean dietary reference intakes for folate, and suggestions for future revisions. Based on the changes in the standard body weight in 2020, the adequate intake (AI) for infants (5-11 months) and the estimated average requirements (EARs) for 15-18 years of age were revised, but there were no changes in the recommended nutrient intakes (RNIs) and tolerable upper intake levels (ULs) for all age groups. Mean folate intake did not reach RNI in most age groups and was particularly low in women aged 15-29 years, according to the results of the 2016-2018 Korea National Health and Nutrition Examination Survey (KNHANES). The percentages of folate intake to RNI were lower than 60% in pregnant and lactating women, but serum folate concentrations were higher than those in other age groups, presumably due to the use of supplements. Therefore, total folate intake, from both food and supplements, should be evaluated. In addition, the database of folate in raw, cooked, and fortified foods should be further expanded to accurately assess the folate intake of Koreans. Determination of the concentrations of erythrocyte folate and plasma homocysteine as well as serum folate is recommended, and quality control of the analysis is critical.

• Applied Chemistry for Engineering
• /
• v.33 no.1
• /
• pp.28-37
• /
• 2022

The lignite and bituminous coal are mainly used in thermal power plant. They exhaust green house gas (GHG) such as CO₂, and become deplete, thus require alternative energy resources. To solve the problem, the hydrochar production from biomass is suggested. In this study, both hydrothermal carbonization (HTC) and solvothermal carbonization (STC) were used to produce high quality hydrochar. To improve the reactivity of water solvent process in HTC, STC process was conducted using ethanol solution. The experiments were carried out by varying the solid-liquid ratio (1:4, 1:8, 1:12), reaction temperature (150~300 ℃) and retention time (15~120 min) using kenaf. The characteristic of hydrochar was analyzed by EA, FT-IR, TGA and SEM. The carbon content of hydrochar increased up to 48.11%, while the volatile matter decreased up to 39.34%. Additionally, the fuel characteristic of hydrochar was enhanced by reaction temperature. The results showed that the kenaf converted to a fuel by HTC and STC process, which can be used as an alternative energy source of coal.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.21 no.6
• /
• pp.115-131
• /
• 2022

Carbon dioxide (CO₂) emissions from the transportation sector in South Korea accounts for 16.5% of all CO₂ emissions, and road transportation accounts for 96.5% of this sector's emissions in South Korea. Hence, constant research is being carried out on methods to reduce CO₂ emissions from this sector. With the emerging use of smart crossings, attempts to monitor individual vehicles are increasing. Moreover, the potential commercial deployment of autonomous vehicles increases the possibility of obtaining individual vehicle data. As such, CO₂ emission research was conducted at five signalized intersections in the Gangnam District, Seoul, using data such as vehicle type, speed, acceleration, etc., obtained from image detectors located at each intersection. The collected data were then applied to the MOtor Vehicle Emission Simulator (MOVES)-Matrix model-which was developed to obtain second-by-second vehicle activity data and analyze daily CO₂ emissions from the studied intersections. After analyzing two large and three small intersections, the results indicated that 3.1 metric tons of CO₂ were emitted per day at each intersection. This study reveals a new possibility of analyzing CO₂ emissions using actual individual vehicle data using an improved analysis model. This study also emphasizes the importance of more accurate CO₂ emission analyses.

• Economic and Environmental Geology
• /
• v.55 no.6
• /
• pp.661-669
• /
• 2022

The need for miniaturization, high efficiency, and green energy resources as an energy storage device through the development of various electronic device has emerged. Accordingly, nanomaterials with excellent electrochemical properties, such as graphene and graphene hybrids, are attracting attention as promising materials. In particular, in the electric vehicle industry, cost reduction of secondary batteries is a key factor that can determine the spread of related industries, and it is most important to analyze R&D trends for battery material technology and respond to future technological development directions. Therefore, in this study, we tried to suggest a direction for R&D activities in the future by analyzing patent trends for graphene anode material technology for secondary batteries and deriving implications. As a result, in the case of anode material technology, the proportion of foreigners in the US and European patent markets was higher than in the Korean and Japanese patent markets, which means that the US and European marketability is high. In addition, Japanese applicants are filing high-level applications not only in the Japanese patent market but also in other countries suggests that Japan is leading the technology in this field. Lastly, the proportion of research institutes in the patent market of Korea and the US remains high compared to that of Japan and Europe, indicating that the commercialization of technology is still slow in those countries. Therefore research institutes and companies in Korea will have to establish their own strategies for developing and securing materials using the results of patent trends in major countries and major companies analyzed in this study.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.22 no.3
• /
• pp.1-19
• /
• 2023

Bikes have recently emerged as an alternative to carbon neutrality. To understand the demand for public bikes, we endeavored to estimate travel frequency of public bike by considering the intermediate stops. Using the GPS trajectory data of 'Ttareungyi', a public bike service in Seoul, we identified a stay point and estimated travel frequency reflecting population, land use, and physical characteristics. Application of map matching and a stay point detection algorithm revealed that stay point appeared in about 12.1% of the total trips. Compared to a trip without stay point, the trip with stay point has a longer average travel distance and travel time and a higher occurrence rate during off-peak hours. According to visualization analysis, the stay points are mainly found in parks, leisure facilities, and business facilities. To consider the stay point, the unit of analysis was set as a hexagonal grid rather than the existing rental station base. Travel frequency considering the stay point were analyzed using the Zero-Inflated Negative Binomial (ZINB) model. Results of our analysis revealed that the travel frequency were higher in bike infrastructure where the safety of bike users was secured, such as 'Bikepath' and 'Bike and pedestrian path'. Also, public bikes play a role as first & last mile means of access to public transportation. The measure of travel frequency was also observed to increase in life and employment centers. Considering the results of this analysis, securing safety facilities and space for users should be given priority when planning any additional expansion of bike infrastructure. Moreover, there is a necessity to establish a plan to supply bike infrastructure facilities linked to public transportation, especially the subway.

• Proceedings of the Plant Resources Society of Korea Conference
• /
• 2022.09a
• /
• pp.82-82
• /
• 2022

천마(天麻, Gastrodia elata Blume)는 난초과(蘭草科, Orchidaceae)에 속하는 식물로 잎과 뿌리가 없어 탄소동화능력이 없으며, 뽕나무버섯균과 공생하는 기생식물이다. 주요 함유된 성분은 gastrodin, 4-hydroxylbenzyl alcohol, vanillin, vanillyl alcohol, ergothioneine 등이 있고, 주로 진정(鎭靜), 진경(鎭痙), 통락(通絡)의 효능이 있으며, 두통, 반신불수, 언어장애, 현훈(眩暈), 고혈압 등에 사용되고 있다. 천마는 노지 재배에 따른 안정생산 문제가 지속적으로 발생하고 있다. 혹한, 폭우 등 기상환경에 따른 연차간 수량성 차가 673~1,175kg/10a로 크고, 정식 후 원목·종균·자마의 공생관계 형성이 늦어져 자마 생존율이 70% 이하로 낮으며, 18개월 장기 재배 시 생육 환경이 불량해져 썩음병이 많이 발생하고 있다. 본 연구는 비가림시설, 종균 선(先) 접종 배양목 및 20g 이상의 자마를 사용하여 재배기간을 18개월에서 12개월로 6개월을 단축하고자 수행하였다. 본 실험은 종균 선접종 배양목 생산을 위해 ^①원목의 종균 접종 시기는 4월 하순, 6월 상순, 7월 중순으로 40일 간격으로 처리하였고, 이렇게 생산된 배양목을 활용하여 정식은 이듬해 4월 상순, 수확은 그 이듬해 3월 하순으로 설정하였다. 또한, 종균 선접종 배양목을 활용한 ^②천마의 정식 시기는 3월 상순, 4월 상순, 5월 상순으로 30일 간격으로 처리하였고, 수확 시기는 이듬해 2월 하순, 3월 하순, 4월 하순으로 설정하여 천마의 생육상황 및 생산성을 조사하였다. ^①원목의 종균 접종시기를 검정한 결과, 자마 생존율은 4월 하순과 6월 상순 처리가 무처리에 비해 15%가 높았고, 천마 수량은 무처리 대비 4월 하순과 6월 상순 처리구에서 각각 2.07배, 1.64배 높았다. ^②천마의 정식 시기를 검정한 결과, 천마의 유효적산온도는 2,400℃로 3월 상순 처리구는 2,446℃로 충족하였고, 4월 중순 처리구는 2,375℃로 거의 충족하였으나, 5월 상순 처리구는 2,178℃로 222℃가 부족하였다. 자마 생존율은 3월 상순 처리 시 95%로 가장 높았고, 정식 시기가 늦어질수록 자마 생존율이 낮아지는 경향을 보였으며, 수량성은 5월 상순 처리 대비 3월 상순이 3.56배, 4월 상순이 3.43배 높았다. 따라서, 자마 생존율, 유효적산온도, 천마 수량성 등의 결과에 따라 원목의 적정 종균 접종 시기는 4월 하순과 6월 상순 사이고, 천마의 적정 정식 시기는 3월 상순과 4월 상순 사이며, 비가림시설, 종균 선접종 배양목 및 우량자마를 활용하면 재배기간을 노지 대비 6개월 이상 단축할 수 있을 것으로 판단되었다.