• 한국연소학회:학술대회논문집
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• 한국연소학회 2013년도 제46회 KOSCO SYMPOSIUM 초록집
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• pp.15-17
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• 2013

In the design of combined cycle power plants, the design parameters considered mainly could be changed and added for performance evaluation with change on the design objective and method. Therefore, the design criteria considering the different objectives and type of power plant were needed. Thermodynamic and economic analyses of various types of gas turbine combined cycle power plants with demand on generation of power and heat and carbon capture system from high pressure flue gas have been performed to establish criteria for optimization of power plants.

• 한국과학교육학회지
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• 제42권4호
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• pp.397-415
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• 2022

최근 지구 온난화 문제가 심각해짐에 따라 탄소 순환에 대한 교육적 요구가 커지고 있다. 이와 관련하여 탄소 순환에 대한 체계적인 이해를 위해 시스템 사고 능력의 접목이 요구되고 있다. 더욱이 급변하는 환경, 사회, 경제적 상황에서, 시스템 사고 교육은 미래 사회를 살아갈 학생들에게 요구되는 역량을 강화할 수 있으므로 더욱 강조되고 있다. 이 연구의 목적은 첫째, 탄소 순환에 대한 시스템 사고 검사 도구를 개발하고 루브릭을 활용한 분석 방법을 구성하고, 둘째, 개발된 검사도구 및 루브릭 분석 방법을 적용하여 학생들의 시스템 사고 능력을 분석하는 것이다. 이 연구를 위해 탄소 순환 및 시스템 사고와 관련된 다양한 선행 연구를 분석하였다. 이 결과를 바탕으로 시스템 사고 검사도구 및 루브릭을 활용한 시스템 사고 능력 분석 방법을 개발하였다. 이를 고등학생 및 대학생 172명에게 적용하여 시스템 사고 능력을 분석하였다. 이 연구의 결과는 다음과 같다. 첫째, 선행연구 분석을 통해 탄소 순환 및 시스템 사고 검사를 위한 시사점을 도출하였고, 탄소 순환에 대한 시스템 사고 검사도구 및 이를 평가하기 위한 루브릭 채점 가이드를 개발하였다. 이를 중학생을 대상으로 예비 투입을 진행하고, 전문가 자문을 통해 최종 완성하였다. 둘째, 개발된 검사도구를 활용하여 학생들의 시스템 사고 능력을 분석한 결과, 학생들은 탄소 순환과 관련된 요인을 식별하는 것과 같은 낮은 수준의 시스템 사고는 잘 수행하였지만, 시간 지연이나 피드백 과정과 같은 높은 수준의 시스템 사고는 부족한 것으로 나타났다. 지구 온난화는 현재 인류가 직면한 가장 시급한 문제 상황으로, 탄소 순환의 중요성이 커지고 있다. 이러한 복잡한 문제 상황은 시스템 사고 능력의 적용을 바탕으로 올바르게 이해하고 근본적인 해결책을 모색할 수 있을 것이다.

• 대한기계학회논문집
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• 제6권2호
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• pp.101-106
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• 1982

This study was undertaken to determine tensile properties and low-cycle fatigue behavior of 0.6%C high carbon steel used of structural purposes at temperatures up to 500.deg.C. In the low-cycle fatigue test the upper limit was decided by elongation(i.e. the total strain range), while the lower limit was defined by the load (i.e. zero load). The following results were obtained. Both, the ultimate tensile strength and low-cycle fatigue resistance attain the maximum values near 250.deg.C. Above this temperature the values decrease rapidly as the temperature increases. The low-cycle fatigue resistance decreases whenever there is an increase of the total strain range. Because the hardness of cycle fatigued specimen correlates cyclic hardening and cyclic softening, therefore the hardness of cycle fatigued specimen is smaller than that of the nonfatigued specimen at room temperature and 500.deg.C but much larger than the hardness of the nonfatigued specimen near 250.deg.C.

• 설비공학논문집
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• 제16권2호
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• pp.158-166
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• 2004

The performance of a heat pump using $CO_2$ is predicted and analyzed by using a cycle simulation model developed in this study. Cycle simulations are conducted by varying design parameters and operating conditions with the applications of advanced techniques to improve system performance. The applied systems in the simulations are internal heat exchanger, expander, and 2-stage compression with intercooling. As a result, the applications of advanced techniques improve the heating and cooling performances of the transcritical $CO_2$ cycle by 8∼26％ and 20∼30％, respectively, over the basic cycle.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2022년도 가을 학술논문 발표대회
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• pp.125-126
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• 2022

As environmental problems around the world become serious, Korea has also raised the greenhouse gas reduction in the building sector to 32.8% compared to 2018, and efforts to reduce carbon in buildings are expanding. Recently, research is being actively conducted to reduce carbon in the long term by expanding the scope of greenhouse gas indirect emissions (Scope3), and even within the domestic Green Standard for Energy and Environmental Design(G-SEED) by quantitatively evaluating the environmental impact of buildings during the entire life cycle. However, it is difficult to accurately evaluate the carbon emission of the transportation process by assuming the material transport distance in the evaluation of the Life Cycle Assessment(LCA). Therefore, in this study, the main building materials of the building were selected through case evaluation and the carbon emission of the material transport process was derived based on the actual transport distance, and this was compared and analyzed with the theoretical LCA results.

• 대기
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• 제25권1호
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• pp.85-97
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• 2015

This study is to investigate future changes in carbon cycle using the HadGEM2-Carbon Cycle simulations driven by $CO_2$ emissions. For experiment, global carbon budget is integrated from the two (8.5/2.6) representative concentration pathways (RCPs) for the period of 1860~2100 by Hadley Centre Global Environmental Model, version 2, Carbon Cycle (Had-GEM2-CC). From 1985 to 2005, total cumulative $CO_2$ amount of anthropogenic emission prescribed as 156 GtC. The amount matches to the observed estimates (CDIAC) over the same period (136 GtC). As $CO_2$ emissions into the atmosphere increase, the similar increasing tendency is found in the simulated atmospheric $CO_2$ concentration and temperature. Atmospheric $CO_2$ concentration in the simulation is projected to be 430 ppm for RCP 2.6 at the end of the twenty-first century and as high as 931 ppm for RCP 8.5. Simulated global mean temperature is expected to rise by $1.6^{\circ}C$ and $3.5^{\circ}C$ for RCP 2.6 and 8.5, respectively. Land and ocean carbon uptakes also increase in proportion to the $CO_2$ emissions of RCPs. The fractions of the amount of $CO_2$ stored in atmosphere, land, and ocean are different in RCP 8.5 and 2.6. Further study is needed for reducing the simulation uncertainty based on multiple model simulations.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2016년도 춘계 학술논문 발표대회
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• pp.259-260
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• 2016

Recently, world-wide focusing on the interest for the reduction of greenhouse gas emissions associated with climate change and global warming, South Korea also has set up a national greenhouse gas reduction target and action plans seeking to achieve them. In particular, in the construction area, to encourage green building certification of the building and carbon labeling acquisition of building products, in order to reduce the environmental impact caused by the industrial activities have been in steady efforts. Therefore, this study estimates the life cycle carbon footprint of building construction materials applied to carbon emissions reduction technology and analyzes the results. Through the CO₂ emissions analysis in construction phase and maintenance phase of the building, it provides basic resource for future research expansion and establishes a step-by-step whole life cycle carbon emissions reduction plan in new construction and existing buildings.

• Advances in materials Research
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• 제7권3호
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• pp.195-201
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• 2018

High Strength low alloy steels containing various levels of C, Nb and Mn were used and for each of which, a simulated double thermal cycle was applied with the same first peak temperature and different second peak temperatures to produce HAZ microstructure corresponding to multi-pass weld. Effect of double cycle second temperature on the microstructure was observed and compared with single cycle results obtained from previous works, it was found that the percentage of martensite austenite constituent (MA) increases by Nb addition for all steels with the same Mn content and the increase in Mn content at the same Nb content shows an increase in MA area fraction as well. MA area fraction obtained for the double cycle is larger than that obtained for the single cycle for all steels used which imply that MA will have great role in the brittle fracture initiation for double cycle and the inter-pass temperature should be controlled for medium and high-carbon Mn steel to avoid large area fraction of MA. The beneficial effects of Niobium obtained in single pass weld were not observed for the double cycle or multi pass welds.

• 상하수도학회지
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• 제27권2호
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• pp.223-232
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• 2013

In this study, carbon emissions and energy consumption were evaluated to establish a design strategy which has low energy consumption and carbon emission production, by using life cycle energy (LCE) and life cycle $CO_2(LCCO_2)$ calculation methods in life cycle management(LCM) tools. After improvement design projects, the energy consumption and $CO_2$ emission were calculated and compared in three sewage treatment plants (STPs), which are A STP, B STP, and C STP. The reduction of carbon emissions was 28,020.1 ton $CO_{2-}e/yr$, 37,399.6 ton $CO_{2-}e/yr$ and 8,788.3 ton $CO_{2-}e/yr$, respectively. Production of energy was 792 TOE/yr, 1,235 TOE/yr and 1,023 TOE/yr, respectively. As a result, the estimation of energy and energy self-sufficiency was 5.1 %, 14.5 % and 23.5 %, respectively. The result of this study shows the LCM can be contributed to establish strategy for energy and carbon emission reduction in sewage treatment plants.

• 과학교육연구지
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• 제45권3호
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• pp.275-291
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• 2021

이 연구의 목적은 인간 활동의 영향을 고려하여 지구 시스템 내에서 물질 순환에 대한 중·고등학생들의 시스템 사고의 수준과 특성을 분석하는 것이다. 이를 위해 2015 개정 교육과정 분석을 통해 평가 문항을 개발하였으며, 시스템 사고를 적용하여 평가 루브릭을 개발하였다. 한국 지구과학 올림피아드에 참여한 중·고등학생을 연구 대상으로 하였다. 평가 문항을 이용하여 수집된 학생 응답을 평가 루브릭을 이용하여 시스템 사고 수준을 결정하였으며, 단어 분석을 이용하여 시스템 사고의 특성을 파악하였다. 이를 토대로 인간 활동의 영향을 고려한 교육과정 개선을 논의하였다. 연구 결과는 다음과 같다: 첫째, 대다수 중등학교 학생의 시스템 사고수준이 물질의 순환에 대한 시스템 요소를 확인하거나 분류하는 낮은 수준이었으며, 시스템 연관이나 경향의 일반화와 같은 높은 수준은 상대적으로 적은 비율인 것으로 나타났다. 물의 순환보다 탄소의 순환에서 학생들의 시스템 사고 수준이 높은 것으로 나타났다. 둘째, 물질 순환에 대한 시스템 사고의 특성은 물의 순환에서는 물을 주요 시스템 요소로 인지한 상태로 기권과 다른 시스템 요소 간에 주로 증발로 연관을 나타내고 있었다. 탄소의 순환에서는 이산화 탄소를 주요 시스템 요소로 간주하여 생물권과의 연관으로 광합성과 호흡을 표상하고 있었다. 셋째, 지구 시스템 내 물질의 순환에서 인간 활동의 영향을 고려한 교육을 위해서 기존의 지구 시스템에서 확장하여 사회-생태 시스템을 고려한 교육과정의 개선을 제언하였다.