• Proceedings of the Korea Concrete Institute Conference
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• 2006.11a
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• pp.137-140
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• 2006

In this study, a seismic performance of reinforced concrete columns strengthened by a sprayed fiber reinforced polymer (SFRP) is investigated. For this purpose, six column specimens approximately scaled into 2/3, are designed and tested under a constant axial load, 10% of the nominal axial strength of column, and pseudo-static reversed cyclic lateral loading system. Four specimens are strengthened by Sprayed FRP using different combinations of short fibers (carbon or glass fiber) and resins (epoxy or vinyl esther). For comparison, the test investigated in this study also includes a specimen strengthened using carbon fiber reinforced polymer (CFRP), and also a control specimen without strengthening. The results revealed that specimens strengthened using SFRP showed a improved structure behavior, compared to control specimen, in terms of strength, ductility, lateral drift capacity, and energy-absorbtion capacity. In addition, compared to the specimen strengthened using CFRP, Sprayed FRP-strengthened specimens reasonably showed a equivalent seismic performance.

• Journal of the Korea Institute of Military Science and Technology
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• v.15 no.4
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• pp.475-491
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• 2012

Green Chemistry emerged at the end of 20th century, which aims the development of the technologies for the sustainable society at the molecular level. Most products we consume in everyday life are produced through chemical processes, and we often oversee the fact that huge amount of solvents are used and disposed. At the present time most solvents used in laboratories as well as industries are volatile organic compounds(VOC), which gives health and environmental problems. Therefore scientists are seeking new materials which have equivalent properties of VOCs as solvent, and at the same time gives no health and environmental problems. In this brief review, the author describes the present status of research and development activities of green solvent materials throughout research societies worldwide. At present the most attractive green solvent candidates are water, glycerol, supercritical carbon dioxide and ionic liquids. In order to give the pictures of these materials, the author tried to introduce the overall aspects of green solvents in various chemical reaction as well as catalytic roles.

• Steel and Composite Structures
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• v.48 no.5
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• pp.485-498
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• 2023

The need for carbon neutrality in the world strives the construction industry to reduce the use of construction materials. Aiming to this, recycled aggregate concrete (RAC) could be used as it reduces the carbon dioxide emissions. Currently, RAC is mainly used in non-structural members of civil constructions, seldom used in structural members. To broaden its structural use, a new type of composite column, i.e., the square and rectangular RAC filled FRP tubes (CFFTs), has been concerned in this study. The investigation on their axial compressive behavior through physical test and numerical analysis demonstrated that the load-carrying capacity of such column is reduced with the increase of replacement ratio of recycled aggregate and aspect ratio of section but can be improved by the increase of FRP confining stiffness and corner radius, said capacity can be equivalent to their steel reinforced concrete counterparts. At failure, the hoop strain at corner of tube is unexpectedly smaller than that at flat side of the tube although the FRP tube ruptured at its corner first, revealing a premature failure. Besides, a design-oriented stress-strain model of concrete and an analysis-oriented finite element model are proposed to predict the load-strain response of square and rectangular CFFT columns, which facilitates the engineering use of RAC in load-carrying structural members.

• Advances in nano research
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• v.14 no.2
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• pp.141-154
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• 2023

Effects of viscoelastic foundation on vibration of curved-beam structure with clamped and simply-supported boundary conditions is investigated in this study. In doing so, a micro-scale laminate composite beam with two piezoelectric face layer with a carbon nanotube reinforces composite core is considered. The whole beam structure is laid on a viscoelastic substrate which normally occurred in actual conditions. Due to small scale of the structure non-classical elasticity theory provided more accurate results. Therefore, nonlocal strain gradient theory is employed here to capture both nano-scale effects on carbon nanotubes and microscale effects because of overall scale of the structure. Equivalent homogenous properties of the composite core is obtained using Halpin-Tsai equation. The equations of motion is derived considering energy terms of the beam and variational principle in minimizing total energy. The boundary condition is assumed to be clamped at one end and simply supported at the other end. Due to nonlinear terms in the equations of motion, semi-analytical method of general differential quadrature method is engaged to solve the equations. In addition, due to complexity in developing and solving equations of motion of arches, an artificial neural network is design and implemented to capture effects of different parameters on the inplane vibration of sandwich arches. At the end, effects of several parameters including nonlocal and gradient parameters, geometrical aspect ratios and substrate constants of the structure on the natural frequency and amplitude is derived. It is observed that increasing nonlocal and gradient parameters have contradictory effects of the amplitude and frequency of vibration of the laminate beam.

• Advances in nano research
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• v.15 no.6
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• pp.551-565
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• 2023

Coupled porous curved beams, due to their low weight and high flexibility, have many applications in engineering. This study investigates the vibration behavior of coupled porous curved beams in different boundary conditions. The system consists of two curved beams connected by a mid-layer of elastic springs. These beams are made of various materials, such as homogenous steel foam, and composite materials with PMMA (polymethyl methacrylate) and SWCNT (single-walled carbon nanotube) used as the matrix and nanofillers, respectively. To obtain equivalent material properties, the role of mixture (RoM) was employed, followed by the implementation of the porosity function. The system's governing equations were obtained by employing FSDT and Hamilton's law. To investigate thermal vibration, temperature was implemented as a load in the governing equations. The GDQ method was used to solve these equations. To demonstrate the applicability of the GDQ method in calculating the frequencies of the system and the correctness of the developed program, a validation study was conducted. After validation, numerous examples were presented to investigate the behavior of single and coupled curved beams in various material properties and boundary conditions. The results indicate that the frequencies of the curved beams and the system depend highly on the amount of porosity (n) and the distribution pattern. The system frequencies decreased with an increase in the porosity coefficient. The stiffness of the springs had no effect on the first mode frequency but increased frequencies of other modes in a specific range. The frequencies of the system decreased with an increase in environmental temperature.

• Applied Biological Chemistry
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• v.17 no.2
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• pp.93-116
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• 1974

A potent intracellular-lipid-producing yeast, Rhodotorula glutinis var. glutinis SW-17, was screened out from a variety of arable soils, compost heaps, and fodders, and two strains of excellent extracellular-lipid-producing yeasts, Rhodotorula glutinis var. glutinis SW-5 and Rhodotorula graminis SW-54, were screened out from the surface of many species of leaves. And then the intra- and extra-cellular lipid productions by those Rhodotorula yeasts were studied. The results were as follows: 1. During the shaking culture of 8 days at $24^{\circ}C$, both the intra- and extra-cellular lipid accumulation started almost at the stationary phase of growth, when the nitrogen source in the medium was a little more than half used up. The intracellular lipid production by Rhodotorula glutinis var. glutinis SW-17 reached 58.42% (w/w) of dried yeast, and the extracellular lipid production by Rhodotorula graminis SW-54 amounted to 2.62g per liter of the medium. 2. After the carbon and nitrogen sources in the medium were almost consumed, if the yeasts were shake-cultured further in a state of starvation, the yeast cells re-utilized the already produced intra- and extra-cellular lipids and the lipids completely disappeared in the medium in about 90 days. 3. The relative concentration of carbon and nitrogen sources in the media greatly influenced both the intra- and extra-cellular lipid production. When the nitrogen source in the medium was almost used up for the growth of yeast, and excess carbon sources were still available, the lipid production vigorously proceeded. As long as the nitrogen source concentration in the medium was high, the lipid production was greatly suppressed. 4. The optimum pH for both the intra- and extra-cellular lipid production by those yeasts was pH 5.0-6.0. 5. The fatty acid components of the intracellular lipid of Rhodotorula glutinis var. glutinis SW-17 were myristic, palmitic, palmitoleic, stearic, oleic, linoleic, and linolenic acids. The largest components of the fatty acids were palmitic acid equivalent to 30-45% of the whole fatty acids and oleic acid equivalent to 35-50%. 6. The fatty acid components of the extracellular lipid of Rhodotorula glutinis var. glutinis SW-5 and Rhodotorula graminis SW-54 were myristic, palmitic, stearic, oleic, linoleic, linolenic, 3-D-hydroxypalmitic, and 3-D-hydroxystearic acids. The largest components of the fatty acids were 3-D-hydroxypalmitic acid equivalent to 22-25% of the acids and 3-D-hydroxystearic acid equivalent to 13-17%. 7. The polyol component of the intracellular lipids was only glycerol, whereas the polyols of extracellular lipids were glycerol, mannitol, xylitol and arabitol.

• Environmental and Resource Economics Review
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• v.32 no.1
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• pp.47-75
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• 2023

Compared to the EU, which legislates the Carbon Border Adjustment System (CBAM), the United States' carbon border adjustment policy movement is still relatively slow. Recently, however, a related bill has been proposed in the United States, and research institutes have been presenting research results on how to introduce an upstream carbon tax rather than an emission trading system and carry out carbon border adjustment based on it. Therefore, in this study, we looked at the economic and environmental effects of introducing this type of upstream carbon tax and carbon border adjustment in Korea. If an upstream carbon tax of KRW 30,000 per ton of CO₂ is applied to the net supply of domestic fossil energy, the expected carbon tax revenue is approximately KRW 22.9961 trillion, equivalent to about 5.7% of the total revenue of the Korean government of KRW 402 trillion in 2019. In addition, the carbon dioxide content of the steel sector, calculated based on the energy supply and demand status of the steel sector, which emits the most greenhouse gas emissions in Korea and has a considerable amount of overseas exports, was 106.22 million tons of CO₂. On the other hand, assuming that the upstream carbon tax of 30,000 won per ton of CO₂ embodied is directly passed on to the production cost of the steel sector, the carbon tax burden in the steel sector is estimated to reach approximately KRW 3.1865 trillion. Even after deducting KRW 1.1599 trillion in export refunds estimated by using the share of exports of steel products, the net carbon tax burden on steel products for domestic demand amounts to KRW 2.0266 trillion, which is analyzed to act as a factor in increasing the price of steel products.

• Korean Journal of Soil Science and Fertilizer
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• v.47 no.5
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• pp.374-380
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• 2014

To estimate greenhouse gas (GHG) emission, the inventory of rice cultivation at the farming without agricultural chemicals was established from farmers in Gunsan, Jeonbuk province in 2011~2012. The objectives of this study were to calculate carbon footprint and analyse the major factor of GHGs. To do this, we carried out a sensitivity analysis using the analyzed main factors of GHGs and estimated the mitigation potential of GHGs. Also we suggested agricultural methods to reduce GHGs that can be appled by farmers at this region. At the farming system without agricultural chemicals, carbon footprint of rice production unit of 1 kg was 2.15 kg $CO_2.-eq.kg^{-1}$. Although the amount of carbon dioxide ($CO_2$) emission was the largest among GHGs, methane ($CH_4$) emission had the highest contribution to carbon footprint on rice production system when it was converted to carbon dioxide equivalent ($CO_2-eq.$) multiplied by the global warming potential (GWP). Main source of $CO_2$ emission in the rice farming system without agricultural chemicals was combustion of fossil fuels used by agricultural machinery. Most of the $CH_4$ was emitted during rice cultivation practice and its major emission factor was flooded paddy field in anaerobic condition. Also, most of the $N_2O$ was emitted from rice cultivation process. Major sources of the $N_2O$ emission was application of fertilizer such as compound fertilizer. As a result of sensitivity analysis in energy consumption, diesel had the highest sensitivity among the energy inputs. With the reduction of diesel consumption by 10%, it was estimated that $CO_2$ potential reduction was about 2.0%. With reducing application rate of compound fertilizer by 10%, the potential reduction was calculated that $CO_2$ and $N_2O$ could be reduced by 0.5% and 0.9%, respectively. At the condition of 10% reduction of silicate and compost, $CO_2$ and $CH_4$ could be reduced by 1.5% and 1.6%, respectively. With 8 days more drainage than the ordinary practice, $CH_4$ emission could be reduced by about 4.5%. Drainage and diesel consumption were the main sources having the largest effect on the GHG reduction at the farming system without agricultural chemicals. Based on the above results, we suggest that no-tillage and midsummer drainage could be a method to decrease GHG emissions from rice production system.

• Proceedings of the Zoological Society Korea Conference
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• 1999.10b
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• pp.11-11
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• 1999

;It has been reported that suspension-cultured rice cells grown on mixed carbon sources of glucose (GIc) and acetate exhibited diauxic growth in which acetate was the preferred carbon source (Lee and Lee, 1996). Carrot (Daucus carota L.) suspension cells, showing a diauxic growth very similar to that of rice cells, were used to delineate the mechanisms underlying this preferential use of acetate over GIc. Uptakes of both GIc and 3-0-methylglucose (3-0MG), a non-metabolizable GIc analogue, were similarly inhibited when acetate or butylate, weak acids which are capable of transporting protons into the cytosol, were present in the uptake assay mixture containing cells harvested during the GIc-utilizing second growth phase. Inhibition of GIc uptake by these weak acids was similar when equivalent experiments were carried out with isolated plasma membranes. It was further shown that Glc uptake, which requires a proper proton gradient across the plasma membranes, was inhibited during the first growth phase by acetate-mediated alkalization of growth medium and/or simultaneous acidification of cytosol. This study strongly suggests that Glc utilization in plant cells is inhibited by co-presenting carbon source(s) which can alter the proton gradient across the plasma membrane. We further examined diauxic growth in culture containing GIc and malate. Unlike the case in the culture with GIc and acetate, carrot cells used GIc first. Malate was utilized only after Glc is depleted from medium. These results indicate that GIc can be a preferred or less-preferred carbon source depending on the competing carbon source. It was noted that malate was not directly taken up by cells. Instead it was converted extracellularly into fumarate which was subsequently transported into cells. During the malate-growth phase malate uptake was negligible, and fumarate uptake was active and pH-sensitive. It was shown that fumarase released into medium was responsible for the extracellular conversion of malate into fumarate. An immunoblot experiments showed that fumarase antibody raised against Arabidopsis fumarase provided positive signals only in medium in malate culture, not in fumarate or GIc cultures. This study demonstrates the first example in that fumarase, a mitochondria marker enzyme, can be present in places other than mitochondria.ndria.

• International Journal of Highway Engineering
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• v.18 no.5
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• pp.83-93
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• 2016

PURPOSES : The aim of this article is to compare and identify eco-friendly competitiveness between (regional) motorway and high-speed rail(HSR) from the perspective of $CO_2$ emission in the Republic of Korea. METHODS : In order for an analysis of low-carbon competitiveness between the two modes, $CO_2e$ emission, $CO_2eppk$ (equivalent $CO_2$ gram per passenger kilometer), is employed as a comparison index. As for HSR, the index is calculated based on the passenger transport data and the gross of $CO_2e$ produced by Kyungbu high-speed line in 2013. Additionally, the gross of $CO_2e$ is computed by the greenhouse gas emission factors of domestic electricity generation mix. Regarding the index of motorway, it is directly calculated using both the official $CO_2e$ emission factor and the passenger-car occupancy of motorway. RESULTS : The results revealed, in the case of inter-regional transport, that the $CO_2e$ emission of displacement-based cars is 54.9% less than that of HSR, as the domestic electric power systems heavily relies on the thermal power plants over 66%. Note that internal combustion engines commonly used for vehicles are more energy-efficient than steam-driven turbines usually utilized for thermal power generation. CONCLUSIONS : It can be seen, at the very least in our study, that HSR has no superiority over motorway in the case of $CO_2e$ emission under the situations of domestic electricity generation mix. In addition, advanced eco-friendly vehicles have strong advantages over HSR. Therefore, all-out efforts should be made to develop and harvest renewable energy sources in order to achieve low-carbon HSR, sparing fossil fuels.