• Title/Summary/Keyword: Carbon cycle

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Research on the Development of the Supercritical CO2 Dual Brayton Cycle (초임계 이산화탄소 이중 브레이튼 사이클 개발 연구)

  • Baik, Young-Jin;Na, Sun Ik;Cho, Junhyun;Shin, Hyung-Ki;Lee, Gilbong
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.40 no.10
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    • pp.673-679
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    • 2016
  • Because of the growing interest in supercritical carbon dioxide power cycle technology owing to its potential enhancement in compactness and efficiency, supercritical carbon dioxide cycles have been studied in the fields of nuclear power, concentrated solar power (CSP), and fossil fuel power generation. This study introduces the current status of the research project on the supercritical carbon dioxide power cycle by Korea Institute of Energy Research (KIER). During the first phase of the project, the un-recuperated supercritical Brayton cycle test loop was built and tested. In phase two, researchers are designing and building a supercritical carbon dioxide dual Brayton cycle, which utilizes two turbines and two recuperators. Under the simulation condition considered in this study, it was confirmed that the design parameter has an optimal value for maximizing the net power in the supercritical carbon dioxide dual cycle.

Electrochemical Characteristics of Silicon/Carbon Composites with CNT for Anode Material (CNT를 첨가한 Silicon/Carbon 음극소재의 전기화학적 특성)

  • Jung, Min zy;Park, Ji Yong;Lee, Jong Dae
    • Korean Chemical Engineering Research
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    • v.54 no.1
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    • pp.16-21
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    • 2016
  • Silicon/Carbon/CNT composites as anode materials for lithium-ion batteries were synthesized to overcome the large volume change during lithium alloying-de alloying process and low electrical conductivity. Silicon/Carbon/CNT composites were prepared by the fabrication processes including the synthesis of SBA-15, magnesiothermic reduction of SBA-15 to obtain Si/MgO by ball milling, carbonization of phenolic resin with CNT and HCl etching. The prepared Silicon/Carbon/CNT composites were analysed by XRD, SEM, BET and EDS. In this study, the electrochemical effect of CNT content to improve the capacity and cycle performance was investigated by charge/discharge, cycle, cyclic voltammetry and impedance tests. The coin cell using Silicon/Carbon/CNT composite (Si:CNT=93:7 in weight) in the electrolyte of $LiPF_6$ dissolved in organic solvents (EC:DMC:EMC=1:1:1 vol%) has better capacity (1718 mAh/g) than those of other composition coin cells. The cycle performance of coin cell was improved as CNT content was increased. It is found that the coin cell (Si:CNT=89:11 in weight) has best capacity retension (83%) after 2nd cycle.

The Effect Analysis of Reducing Carbon Emission by Design Parameter Change and Material Properties (변수 변경 및 재료적 특성에 따른 철골 구조물의 탄소 배출량 절감 효과 분석)

  • Song, Chang-Hyun;Jang, Arum;Ju, Young K.
    • Journal of Korean Association for Spatial Structures
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    • v.23 no.3
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    • pp.105-113
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    • 2023
  • The study used the whole-life carbon assessment method to conduct a thorough carbon-neutral evaluation of a standard steel structure. To further assess carbon emissions, 11 design-changed models were evaluated, with changes made to the span between beams and columns. The results of the carbon emission assessment showed savings of approximately 13.1% by implementing the stage of the beyond life cycle. Additionally, the evaluation of carbon emissions through design changes revealed a difference of up to 42.2%. These findings confirmed that recycling and structural design changes can significantly reduce carbon emissions by up to 48.6%, making it an effective means of achieving carbon neutrality. It is therefore necessary to apply the stage of beyond life cycle and structural change to reduce carbon emissions.

A Study on the Power Generation Using Supercritical Carbon Dioxide (초임계 이산화탄소를 활용한 발전에 대한 연구)

  • NOH, SANGGYUN
    • Journal of Hydrogen and New Energy
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    • v.30 no.4
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    • pp.297-302
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    • 2019
  • In this paper, the power generation efficiency increase has been studied for a Rankine cycle using both supercritical carbon dioxide as a working fluid and LNG as a coolant with PRO/II with PROVISION release 10.0 from Aveva company. Peng-Robinson equation of the state model with Twu's alpha function was selected for the modeling of the power generation cycle using LNG cold heat. Power generation efficiency was increased from 24.82% to 57.76% when using LNG as a coolant for supercritical carbon dioxide power generation cycle.

Global Carbon Cycle Under the IPCC Emissions Scenarios (IPCC 배출시나리오에 따른 지구 규모의 탄소 이동 연구)

  • Kwon, O-Yul
    • Journal of Environmental Science International
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    • v.16 no.3
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    • pp.287-297
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    • 2007
  • Increasing carbon dioxide emissions from fossil fuel use and land-use change has been perturbing the balanced global carbon cycle and changing the carbon distribution among the atmosphere, the terrestrial biosphere, the soil, and the ocean. SGCM(Simple Global Carbon Model) was used to simulate global carbon cycle for the IPCC emissions scenarios, which was six future carbon dioxide emissions from fossil fuel use and land-use change set by IPCC(Intergovernmental Panel on Climate Change). Atmospheric $CO_2$ concentrations for four scenarios were simulated to continuously increase to $600{\sim}1050ppm$ by the year 2100, while those for the other two scenarios to stabilize at $400{\sim}600ppm$. The characteristics of these two $CO_2$-stabilized scenarios are to suppress emissions below $12{\sim}13$ Gt C/yr by tile year 2050 and then to decrease emissions up to 5 Gt C/yr by the year 2100, which is lower than the current emissions of $6.3{\pm}0.4$ Gt C/yr. The amount of carbon in the atmosphere was simulated to continuously increase for four scenarios, while to increase by the year $2050{\sim}2070$ and then decrease by the year 2100 for the other two scenarios which were $CO_2$-stabilized scenarios. Even though the six emission scenarios showed different simulation results, overall patterns were such similar that the amount of carbon was in the terrestrial biosphere to decrease first several decades and then increase, while in the soil and the ocean to continuously increase. The ratio of carbon partitioning to tile atmosphere for the accumulated total emissions was higher for tile emission scenario having higher atmospheric $CO_2$, however that was decreasing as time elapsed. The terrestrial biosphere and the soil showed reverse pattern to the atmosphere.

Global Carbon Cycle and Budget Study (지구규모의 탄소 순환 및 물질수지 연구)

  • 권오열
    • Journal of Environmental Science International
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    • v.5 no.4
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    • pp.429-440
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    • 1996
  • A global carbon cycle model (GCCM), that incorporates interaction among the terrestrial biosphere, ocean, and atmosphere, was developed to study the carbon cycling aid global carbon budget, especially due to anthropogenic $CO_2$ emission. The model that is based on C, 13C and 14C mass balance, was calibrated with the observed $CO_2$ concentration, $\delta$13C and $\Delta$14C in the atmosphere, Δ14C in the soil, and $\Delta$14C in the ocean. Also, GCCM was constrained by the literature values of oceanic carbon uptake and CO, emissions from deforestation. Inputs (forcing functions in the model) were the C, 13C and 14C as $CO_2$ emissions from fossil fuel use, and 14C injection into the stratosphere by bomb-tests. The simulated annual carbon budget of 1980s due to anthropoRenic $CO_2$ shows that the global sources were 5.43 Gt-C/yr from fossil fuel use and 0.91 Gt-C/yr from deforestation, and the sinks were 3.29 Gt-C/yr in the atmosphere, 0.90 Gt-C/yr in the terrestrial biosphere and 2.15 Gt-C/yr in the ocean. The terrestrial biosphere is currently at zero net exchange with the atmosphere, but carbon is lost cia organic carbon runoff to the ocean. The model could be utilized for a variety of studies in $CO_2$ policy and management, climate modeling, $CO_2$ impacts, and crop models.

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Analysis of Water Cycle Effect by Plan of LID-decentralized Rainwater Management Using SWMM-LID Model in a Low-carbon Green Village (SWMM-LID를 이용한 저탄소 녹색마을의 LID-분산형 빗물관리 계획에 따른 물순환 효과 분석)

  • Lee, Jung-Min;Hyun, Kyoung-Hak;Lee, Yun-Sang;Kim, Jung-Gon;Park, Yong-Boo;Choi, Jong-Soo
    • Land and Housing Review
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    • v.2 no.4
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    • pp.503-507
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    • 2011
  • There was a plan to develop a low-carbon green village(approximately $400,000m^2$) in A city, a new town. Restoration of water cycle is essential for creation of the low-carbon green village. Therefore, installation plan of LID-decentralized rainwater management facilities for natural water cycle was established for creation of the low-carbon green village. Analyses on effect of the water cycle were performed in conditions of before, after developing the low-carbon green village and after installing the LID facilities(rain garden, constructed wetland, rainwater harvesting facility, etc.) using SWMM-LID model developed by EPA. Due to the characteristic of permeable area before development and significant green spaces after development, installation plan of LID facilities to restore the water cycle did not show an obvious effect. However, potential of the hydrological cycle could be seen by the installation of the LID facilities.

A Carbon Cycle Model Based Method for Carbon Neutrality Assessment (탄소순환 모델기반 탄소중립 평가방법)

  • Choi, Soo Hyoung
    • Korean Chemical Engineering Research
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    • v.60 no.3
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    • pp.433-438
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    • 2022
  • A carbon cycle model based method is proposed in order to evaluate the effectiveness of various policies and projects to achieve carbon neutrality. The proposed model was validated by properly reproducing the increase in the concentration of carbon dioxide in the atmosphere and the rise of the global average temperature from the data of anthropogenic carbon emissions and deforestation since the industrial revolution. As a case study, a carbon cycle impact assessment was performed for deforestation, reforestation, and afforestation. It was verified that the increase of carbon dioxide in the atmosphere is attributed not only to fossil fuel usage, but also to deforestation, and that even if deforestation is immediately followed by reforestation, it takes very long to return to the initial concentration. The proposed method is expected to be eventually applicable to simulation of potential climate control in the future, contributing to safety verification of various climate engineering techniques.

Macro-level Methodology for Estimating Carbon Emissions, Energy Use, and Cost by Road Type and Road Life Cycle (도로 종류와 도로생애주기별 탄소배출량, 에너지소모량 및 비용에 대한 거시적 분석방법)

  • Hu, Hyejung;Baek, Jongdae
    • International Journal of Highway Engineering
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    • v.17 no.2
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    • pp.143-150
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    • 2015
  • PURPOSES : The authors set out to estimate the related carbon emissions, energy use, and costs of the national freeways and highways in Korea. To achieve this goal, a macro-level methodology for estimating those amounts by road type, road structure type, and road life cycle was developed. METHODS : The carbon emissions, energy use, and costs associated with roads vary according to the road type, road structure type, and road life cycle. Therefore, in this study, the road type, road structure type, and road life cycle were classified into two or three categories based on criteria determined by the authors. The unit amounts of carbon emissions and energy use per unit road length by classification were estimated using data gathered from actual road samples. The unit amounts of cost per unit road length by classification were acquired from the standard cost values provided in the 2013 road business manual. The total carbon emissions, energy use, and cost of the national freeways and highways were calculated by multiplying the road length by the corresponding unit amounts. RESULTS: The total carbon emissions, energy use, and costs associated with the national freeways and highways in Korea were estimated by applying the estimated unit amounts and the developed method. CONCLUSIONS: The developed method can be employed in the road planning and design stage when decision makers need to consider the impact of road construction from an environmental and economic point of view.

Effects of Impregnation on the Manufacture of High Density Carbon Materials (고밀도 탄소재 제조시의 함침효과)

  • 염희남;김경자;이종민;정윤중
    • Journal of the Korean Ceramic Society
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    • v.30 no.10
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    • pp.852-858
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    • 1993
  • The effect of coal tar ptch-impregnated carbon materials which were made from petroleum coke was investigated at various pressure time and impregnation-sintering cycle. As a result, density and bending strength of the carbon materials were remarkably increased in the condition of pressure times of 5hrs and of the cycle of 3rd times. And the value of d002 and Lc of the graphitic carbon sintered at 230$0^{\circ}C$ shwoed 3.387$\AA$ and 167$\AA$, respectively.

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