• 방사성폐기물학회지
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• 제18권2호
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• pp.169-177
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• 2020

Here, the stability of stainless steel 316 (SS-316) was investigated to identify its applicability in the oxide reduction process, as a component in related equipment, to produce a complicated gas mixture composed of O₂ and Cl₂ under an argon (Ar) atmosphere. The effects of the mixed gas composition were investigated at flow rates of 30 mL/min O₂, 20 mL/min O₂ + 10 mL/min Cl₂, 10 mL/min O₂ + 20 mL/min Cl₂, and 30 mL/min Cl₂, each at 600℃, during a constant argon flow rate of 170 mL/min. It was found that the corrosion of SS-316 by the chlorine gas was suppressed by the presence of oxygen, while the reaction proceeded linearly with the reaction time regardless of gas composition. Surface observation results revealed an uneven surface with circular pits in the samples that were fed mixed gases. Thermodynamic calculations proposed the combination of Fe and Ni chlorination reactions as an explanation for this pit formation phenomenon. An exponential increase in the corrosion rate was observed with an increase in the reaction temperature in a range of 300 ~ 600℃ under a flow of 30 mL/min Cl₂ + 170 mL/min Ar.

• 환경영향평가
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• 제21권2호
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• pp.255-264
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• 2012

The present study attempts to understand the emission pattern of greenhouse gases in people's daily life through the estimation and analysis of the amount and characteristics of the greenhouse gases. Based on the survey of 1,000 people throughout the nation, monthly emission of greenhouse gases per-capita was estimated from their use of fuels, electricity, water, and personal and public transportation means in addition to their waste generation. In the case of personal car drivers, greenhouse gas emission was the greatest from their cars, followed by the emission from electricity, fuels, and public transportation. Emission from water consumption and waste generation was relatively low. Fuel consumption varied depending on the number of household members, their housing type, and the size of their living spaces. Results showed that single-person households emitted the largest amount of per-capita greenhouse gas while greenhouse gas emission from electricity was inversely proportional to the number of persons in a given household.

• Advances in Energy Research
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• 제3권3호
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• pp.167-179
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• 2015

This paper presents a techno-economic analysis of a partial repowering scheme for an existing 210 MW coal fired power plant by integrating a gas turbine and by employing waste heat recovery. In this repowering scheme, one of the four operating coal mills is taken out and a new natural gas fired gas turbine (GT) block is considered to be integrated, whose exhaust is fed to the furnace of the existing boiler. Feedwater heating is proposed through the utilization of waste heat of the boiler exhaust gas. From the thermodynamic analysis it is seen that the proposed repowering scheme helps to increase the plant capacity by about 28% and the overall efficiency by 27%. It also results in 21% reduction in the plant heat rate and 29% reduction in the specific $CO_2$ emissions. The economic analysis reveals that the partial repowering scheme is cost effective resulting in a reduction of the unit cost of electricity (UCOE) by 8.4%. The economic analysis further shows that the UCOE of the repowered plant is lower than that of a new green-field power plant of similar capacity.

• 한국방사성폐기물학회:학술대회논문집
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• 한국방사성폐기물학회 2017년도 춘계학술논문요약집
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• pp.153-154
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• 2017

The thermal analysis of transportation and storage cask for SNF was conducted during short term loading operations for forced gas drying condition. The fuel cladding temperature in 6 regions of SNF in the cask during the short term loading operations for forced gas drying condition is shown in the Fig. 3. The thermal analysis results of calculated maximum cladding temperature in each process demonstrate that operating scenario of TFD in detailed design maintain well below the temperature limits of $400^{\circ}C$.

• 청정기술
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• 제19권2호
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• pp.113-120
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• 2013

화학적으로 안정한 과불화합물을 처리하기 위해서는 많은 양의 에너지를 필요로 한다. 이러한 단점을 극복하기 위해서 저전력 아크 플라즈마 시스템을 개발하였다. 분해대상은 $CF_4$, $SF_6$, $NF_3$가 플라즈마 토치로 직접 주입되었으며, 아크 플라즈마 토치의 열효율을 측정하여 실출력을 계산하였다. 실출력과 폐기체 유량 변화 그리고 추가적인 반응가스에 의한 분해효율을 확인하였다. 또한 열역학적 평형조성 분석을 수행하여 실험 결과와 비교하였다. 토치의 열효율은 60~66%의 결과를 보였으며 폐가스 유량이 증가함에 따라 분해효율이 감소하였고 입력전력이 늘어남에 따라 분해효율이 상승되었다. 추가적인 반응 가스가 없이 $CF_4$, $SF_6$, $NF_3$의 분해효율은 입력전력이 3 kW, 폐가스 유량이 70 L/min인 조건에서 각각 4, 15, 90%를 보였다. 반응가스로 산소와 수소를 이용하여 분해효율을 급격하게 증가시킬 수 있었으며, 실험 결과 산소보다 수소를 사용하였을 경우가 분해효율 상승효과와 부산물 제어에 효과적인 것을 알 수 있었다. 수소의 경우, 발생되는 부산물은 불화수소산이었으며 이는 일반적인 습식 스크러버를 이용하여 처리가 용이한 물질이다. 수소를 이용한 화학반응에서 입력전력이 3 kW, 폐가스유량이 100 L/min인 조건에서 $CF_4$가 25%, $SF_6$가 39%, $NF_3$가 99%의 분해효율을 각각 나타냈다.

• Asian Journal of Atmospheric Environment
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• 제2권2호
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• pp.116-124
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• 2008

In this study, the Tier 2 method recommended by the Intergovernmental Panel on Climate Change (IPCC) was used to predict the methane generation rate at two landfill sites, designated as Y and C for purposes of this study, in South Korea. Factors such as the average annual waste disposal, methane emissions ($L_0$) and methane gas generation rate constant (k) were estimated by analyses of waste and the historical data for the landfills. The value of k was estimated by field experiments and then the changes in the methane generation rate were predicted through the year 2050, based on the value of k. The Y landfill site, which was in operation until the year 2008, will generate a total of 17, 198.7 tons by the end of 2018, according to our estimations. At the C landfill site, which will not be closed until the end of 2011, the amount of methane gas generated in 2011 will be 3,316 tons and the total amount of gas generated by 2029 will be 61,200 tons. The total production rate of methane gas at the C landfill is higher than that of the Y landfill. This indicates that the capacity of a landfill site affects the production rate of methane gas. However, the interrelation between the generation rate of methane and the value of k is weak. In addition, the generation of methane gas does not cease even when the operations at a landfill site come to a close and the methane gas production rate is at its highest at end of the operating life of a landfill site.

• 자원리싸이클링
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• 제20권2호
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• pp.3-15
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• 2011

현재 CDM사업 등록은 대부분 에너지, 화학공정, 제조공정 분야에서 이루어지고 있다. 그러나, 무기질 자원재활용을 통한 CDM사업 등록은 그렇게 많지 않은 실정이다. 본 논문에서는 국내 무기질 폐기물의 재자원화를 통한 CDM사업 등록 가능성을 알아보기 위하여 국내외 CDM사업 현황 분석 및 적용사례를 조사하였다. 조사결과 CDM사업 등록 사례는 대량으로 활용할 수 있는 산업 중의 하나인 시멘트산업의 원료 대체화 분야에서 다수의 등록이 이루어진 것으로 조사되었다. 우리나라에서의 CDM사업 적용 전망은 산업의 규모, 무기질 자원 활용 산업 및 온실가스 배출량을 분석하고 대량으로 활용할 수 있을 정도로 지속적으로 발생되는 우기질 폐가물의 현황 등을 면밀히 검토해야 할 것으로 판단된다.

• 웰빙융합연구
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• 제7권3호
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• pp.31-42
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• 2024

Purpose: Open-air dumping is a significant problem in Gilgit City, with limited research analyzing waste generation and its physicochemical impact on the soil. This study aimed to evaluate the effects of open dumping on soil properties and compare them with a controlled site. Research Design, data, and Methodology: Using ANOVA, the study found significant differences in electrical conductivity (EC), soil organic matter (SOM), soil organic carbon (SOC), sand, silt, and clay between the two sites, except for pH. Pearson correlation revealed that pH negatively correlated with EC, sand, and silt, but positively with SOM, SOC, and clay. The control site's mean EC was 6.06 mS/m, whereas the dumping site recorded 8.5 mS/m. EC is inversely related to SOM, SOC, silt, and clay, but directly to sand. SOC and SOM values varied significantly, with notable differences in soil texture components like clay and silt. Results: The research highlights the detrimental effects of unsystematic waste dumping on soil health and its contribution to greenhouse gas emissions, particularly methane, which exacerbates climate change. Conclusion: The study concluded that waste deposition and decomposition significantly impact EC, SOM, SOC, and soil texture, though pH remains unchanged. The unsystematic dumping of solid waste contributes to climate change through methane production, a potent greenhouse gas. To mitigate these impacts, the study recommends regular monitoring, waste prevention, recycling strategies, and continuous training for stakeholders to achieve sustainable development.

• 한국환경보건학회지
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• 제36권2호
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• pp.136-140
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• 2010

The integrated gasification combined cycle (IGCC) is one of the most promising proposed processes for advanced electric power generation that is likely to replace conventional coal combustion. This emerging technology will not only improve considerably the thermal efficiency but also reduce or eliminate the environmentally adverse effects normally associated with coal combustion. The IGCC process gasifies coal under reducing conditions with essentially all the sulfur existing in the form of hydrogen sulfide ($H_2S$) in the product fuel gas. The need to remove $H_2S$ from coal derived fuel gases is a significant concern which stems from stringent government regulations and also, from a technical point of view and a need to protect turbines from corrosion. The waste seashells were used for the removal of hydrogen sulfide from a hot gas stream. The sulphidation of waste seashells with $H_2S$ was studied in a thermogravimetric analyzer at temperature between $600^{\circ}C$ and $800^{\circ}C$. The desulfurization performance of the waste seashell sorbents was experimentally tested in a fixed bed reactor system. Sulfidation experiments performed under reaction conditions similar to those at the exit of a coal gasifier showed that preparation procedure and technique, the type and the amount of seashell, and the size of the seashell affects the $H_2S$ removal capacity of the sorbents. The pore structure of fresh and sulfided seashell sorbents was analyzed using mercury porosimetry, nitrogen adsorption, and scanning electronmicroscopy.

• International Journal of Concrete Structures and Materials
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• 제9권3호
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• pp.295-306
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• 2015

Simulating natural leaching process for cementitious materials is essential to perform long-term safety assessments of repositories for nuclear waste. However, the current test methods in literature are time consuming, limited to crushed material and often produce small size samples which are not suitable for further testing. This paper presents the results from the study of the physical (gas permeability as well as chloride diffusion coefficient) and mechanical properties (tensile and compressive strength and elastic modulus) of solid cementitious specimens which have been depleted in calcium by the use of a newly developed method for accelerated calcium leaching of solid specimens of flexible size. The results show that up to 4 times increase in capillary water absorption, 10 times higher gas permeability and at least 3 times higher chloride diffusion rate, is expected due to complete leaching of the Portlandite. This coincides with a 70 % decrease in mechanical strength and more than 40 % decrease in elastic modulus.