• Journal of Astronomy and Space Sciences
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• 제37권2호
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• pp.85-94
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• 2020

Equatorial noise, also known magnetosonic waves (MSWs), are one of the frequently observed plasma waves in Earth's inner magnetosphere. Observations have shown that wave amplitudes maximize at the magnetic equator with a narrow extent in their latitudinal distribution. It has been understood that waves are generated from an equatorial source region and confined within a few degrees magnetic latitude. The present study investigates whether the MSW instability and saturation amplitudes maximize at the equator, given an energetic proton ring-like distribution derived from an observed wave event, and using linear instability analysis and particle-in-cell simulations with the plasma conditions at different latitudes along the dipole magnetic field line. The results show that waves initially grow fastest (i.e., with the largest growth rate) at high latitude (20°-25°), but consistent with observations, their saturation amplitudes maximize within ±10° latitude. On the other hand, the slope of the saturation amplitudes versus latitude revealed in the present study is not as steep as what the previous statistical observation results suggest. This may be indicative of some other factors not considered in the present analyses at play, such as background magnetic field and plasma inhomogeneities and the propagation effect.

• 한국대기환경학회지
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• 제26권6호
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• pp.657-665
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• 2010

Carbon dioxide ($CO_2$) is known to be a major greenhouse gas partially emitted from waste combustion facilities. According to the greenhouse gas emission inventory in Korea, the quantity of the gas emitted from waste sector in 2005 represents approximately 2.5 percent of all domestic greenhouse gas emission. Currently, the emission rate of greenhouse gas from the waste sector is relatively constant partly because of both the reduced waste disposal in landfills and the increased amounts of waste materials for recycling. However, the greenhouse gas emission rate in waste sectors is anticipated to continually increase, mainly due to increased incineration of solid waste. The objective of this study was to analyze the property of Municipal Solid Waste (MSW) and estimate $CO_2$ emissions from domestic MSW incineration facilities. The $CO_2$ emission rates obtained from the facilities were surveyed, along with other two methods, including Tier 2a based on 2006 IPCC Guideline default emission factor and Tier 3 based on facility specific value. The $CO_2$ emission rates were calculated by using $CO_2$ concentrations and gas flows measured from the stacks. Other parameters such as waste composition, dry matter content, carbon content, oxidation coefficient of waste were included for the calculation. The $CO_2$ average emission rate by the Tier 2a was 34,545 ton/y, while Tier 3 was 31,066 ton/y. Based on this study, we conclude that Tier 2a was overestimated by 11.2 percent for the $CO_2$ emission observed by Tier 3. Further study is still needed to determine accurate $CO_2$ emission rates from municipal solid waste incineration facilities and other various combustion facilities by obtaining country-specific emission factor, rather than relying on IPCC default emission factor.

• 한국체육학회지인문사회과학편
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• 제54권5호
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• pp.829-840
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• 2015

본 연구는 정상시를 가진 정상인을 대상으로 입체시 부족을 유발하여 장애물 보행 시 발생될 것으로 생각되는 하지관절의 운동 변화에 대한 운동학적 분석과 지면반력의 변화를 고찰하는 것이다. 본 연구의 대상자는 입체시 테스트를 거쳐 통과한 18명이 연구에 참여하였다(age: 22.1±2.7 years, height: 176.8±4.4 cm, weight: 67.6±5.8 kg). 3차원 동작분석 시스템과 지면반력기를 이용하여 분석한 결과는 다음과 같다. 보행속도는 장애물 보행 시 느리게 나타났다. 고관절 각변위는 대부분 보행구간에서 장애물 보행 시 굴곡이 크게 나타났다. 무릎관절 각변위는 모든 보행구간에서 장애물 보행 시 굴곡이 크게 일어났고, TO와 FC2에서 입체시 감소의 영향으로 굴곡이 크게 나타났다. 발목관절 각 변위는 FC2에서 장애물 보행 시 굴곡이 크게 나타났다. 몸통기울기는 MSt, TO, MSw에서 장애물 보행 시 신전이 크게 나타났다. 지면반력은 Fx 값(내외측힘)에서 차이가 나타나지 않았지만, Fy 값(전후힘)에서 좌우발 모두 장애물 보행 시 전방 최대힘(추진력)이 크게 나타났고, 후방 최대힘(제동력)은 오른발은 입체시부족 보행 시 크게 나타났으며, 왼발은 장애물 보행 시 크게 나타났다. Fz 값(수직힘)은 최대힘-1과 최대힘-2에서 좌우발 모두 장애물 보행 시 최대 힘이 크게 나타났고, 계곡힘에서 오른발은 입체시부족 보행이 정상시 보행보다 작은힘이 나타났다.

• 유기물자원화
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• 제18권3호
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• pp.77-86
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• 2010

본 연구에서는 간접흡입식 풍력선별기의 모델에 대하여 폐기물의 선별특성을 전산유체역학적인 방법으로 고찰하여 폐기물 모델에 대한 적정한 항력계수 및 흡입풍속에 대한 결과를 얻었다. 개발중인 풍력선별기는 송풍기를 설치하여 공기를 사이클론 후단에서 흡입하는 방식으로 선별 폐기물이 송풍기 회전차를 통과하지 않는 특징이 있으며, 흡입구의 특성 및 배관의 압력손실이 선별효율에 큰 영향을 미칠 수 있다. 풍력선별기를 이용한 폐기물을 선별하기 위해서는 폐기물의 공기역학적 특성에 대한 사전연구가 필수적이다. 비닐의 경우 약 0.8~1.0 내외의 항력계수를 적용하는 것이 타당하며, 캔은 압축여부에 따라 차이가 있으나 0.2~0.7의 범위에 있다. 풍력선별기의 흡입유속에 따른 선별효율은 약 25~26 m/s의 흡입유속에서 가장 높은 효율을 얻었다. 흡입구의 형상, 이송덕트의 배관방법에 따라 압력손실이 발생하여 흡입유속이 변화하므로 표준화를 통해 적절한 설계가 가능하도록 지속적인 연구가 필요하다.

• Environmental Engineering Research
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• 제24권2호
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• pp.220-237
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• 2019

Solid waste management (SWM) is one of the poorly rendered services in developing countries - limited resources, increasing population, rapid urbanization and application of outdated systems leads to inefficiency. Lack of proper planning and inadequate data regarding solid waste generation and collection compound the SWM problem. Decision makers need to formulate solutions that consider multiple goals and strategies. Given the large number of available options for SWM and the inter-relationships among these options, identifying SWM strategies that satisfy economic or environmental objectives is a complex task. The paper develops a mathematical model for a municipal Integrated SWM system, taking into account waste generation rates, composition, transportation modes, processing techniques, revenues from waste processing, simulating waste management as closely as possible. The constraints include those linking waste flows and mass balance, processing plants capacity, landfill capacity, transport vehicle capacity and number of trips. The linear programming model integrating different functional elements was solved by LINGO optimization software and various possible waste management options were considered during analysis. The model thus serves as decision support tool to evaluate various waste management alternatives and obtain the least-cost combination of technologies for handling, treatment and disposal of solid waste.

• 한국환경보건학회지
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• 제32권1호
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• pp.8-18
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• 2006

The aim of this study is to evaluate the emission characteristics of mercury, lead, arsenic, and selenium from medium size municipal solid waste incinerators(MSWIs) in Korea. The concentrations of mercury, lead, arsenic, and selenium emitted from medium size MSWI stack were $2.67\;{\mu}g/Sm^3,\;0.38\;mg/Sm^3,\;1.33\;{\mu}g/Sm^3,\;0.28\;{\mu}g/Sm^3$, respectively. The concentration levels of mercury, lead, arsenic in flue gas from medium size MSW incinerator stacks selected were nearly detected under the Korea criteria level. Removal efficiencies of mercury, lead, arsenic, and selenium in waste heat boiler(WHE) and cooling tower(CT) were $90.36\%,\;69.76\%,\;43.04\%,\;40.64\%$, respectively. In general, the removal efficiencies of mercury and lead in WHE were higher than those of arsenic and selenium in WHE. Emission gas temperature reduction from waste heat boiler(WHB) and cooling tower(CT) can control mercury and lead of medium size MSWIs. To evaluate the relationship between mercury, lead, arsenic, selenium of fly ash and those of flue gas, it was carried out to correlation analysis of each metal concentration in the fly ash and in the flue gas from medium size MSWIs. From the correlation analysis, the coefficients of mercury, lead, arsenic, and selenium were 0.61, -0.38, 0.87, 0.28, respectively. The results of correlation analysis revealed that it should be highly positive to the correlation coefficients of mercury and arsenic in the fly ash and those of the flue gas emitted from medium size MSWIs. As it were, the concentrations of mercury and arsenic of flue gas from medium size MSWIs are high unless mercury and arsenic in fly ash are properly controlled in dust collection step in medium size MSWIs. It was also concluded that mercury, lead, arsenic, and selenium from MSWIs stacks could be controlled by waste heat boiler(WHE) and dust collecting step in medium size MSWIs.

• 유기물자원화
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• 제16권1호
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• pp.70-78
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• 2008

본 연구에서는 경기도 B지역 학교 폐기물의 성상 및 물리 화학적 특성을 조사하였다. 이것은 폐기물 재활용 및 자원화시설 설계를 위한 기초자료로 활용할 수 있게 하고자 한다. 학교폐기물의 물리적 조성의 실험결과 음식 쓰레기 12.25%, 종이류 56.26%, 플라스틱과 비닐류 9.26%, 섬유 1.52%, 나무 3.70%, 고무 및 피혁류와 기타는 0.11%이다. 학교폐기물의 대부분은 종이류와 플라스틱류이고, 약 90%가 가연성분인 것으로 나타났다. 삼성분 분석 결과 수분 5.72%, 가연분 88.29%, 그리고 회분 5.98%로 나타났으며, 농촌지역 학교 폐기물 성분중 수분이 도시지역 학교보다 높게 나왔다. 건조된 폐기물의 원소 분석 결과 탄소, 산소, 수소가 높게 나왔으며 학교폐기물의 저위발열량은 3051.44kcal/kg로 조사되어졌다.

• 한국환경과학회지
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• 제25권2호
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• pp.239-246
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• 2016

This study aims to analyze region-specific trends in changing greenhouse gas emissions in incineration plants of local government where waste heat generated during incineration are reused for the recent five years (2009 to 2013). The greenhouse gas generated from the incineration plants is largely $CO_2$ with a small amount of $CH_4$ and $N_2O$. Most of the incineration plants operated by local government produce steam with waste heat generated from incineration to produce electricity or reuse it for hot water/heating and resident convenience. And steam in some industrial complexes is supplied to companies who require it for obtaining resources for local government or incineration plants. All incineration plants, research targets of this study, are using LNG or diesel fuel as auxiliary fuel for incinerating wastes and some of the facilities are using LFG(Landfill Gas). The calculation of greenhouse gas generated during waste incineration was according to the Local Government's Greenhouse Emissions Calculation Guideline. As a result of calculation, the total amount of greenhouse gas released from all incineration plants for five years was about $3,174,000tCO_2eq$. To look at it by year, the biggest amount was about $877,000tCO_2eq$ in 2013. To look at it by region, Gyeonggido showed the biggest amount (about $163,000tCO_2eq$ annually) and the greenhouse gas emissions per capita was the highest in Ulsan Metropolitan City(about $154kCO_2eq$ annually). As a result of greenhouse gas emissions calculation, some incineration plants showed more emissions by heat recovery than by incineration, which rather reduced the total amount of greenhouse gas emissions. For more accurate calculation of greenhouse gas emissions in the future, input data management system needs to be improved.

• 환경위생공학
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• 제16권2호
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• pp.63-70
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• 2001

This study was initiated to evaluate and resolve the potential problems caused as the MSWI(Municipal Solid Waste Incinerator) fly ash were stabilized and solidified into the cement. The physical and chemical properties of fly ashes (K and M) used in this study were fixed according to the operating conditions of the incineration plant. The compressible strength of the solidified matrix used in this study were measured at 7, 28, and 56 curing days, respectively, to evaluate the stability of the solidified matrix, which were further analyzed by XRD and SEM. The experimental results obtained in this study showed that the relatively long hours of curing periods were needed to solidify the fly ash. The solidified matrix containing K ash had the high and excellent compressible strength of $200{\;}kg/\textrm{cm}^2$, after 56 curing days, but was not good enough in appearance. The analytical data by SEM confirmed that the alkaline Na and K, which are highly dissolved in water, were included in the fly ash and evenly distributed into the exterior surface of the solidified matrix. Whereas, the solidified matrix containing M ash never showed such a compressible strength as shown in the K ash due to the severe fracture, even as early as 7 curing days. Based on its XRD analysis, it appeared that both $C_2S$ and $C_3S$ highly related to the compressible strength were not crystallyzed into the solidified matrix. However, the compressible strength of the solidified and cemented M ash was remarkably improved by 100 times, after the alkalinity was washed out, which indicated that it is equivalent to 30 to 40g per one kg of fly ash.

• 공업화학
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• 제19권3호
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• pp.259-263
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• 2008

소각로에서 발생한 다이옥신 및 질소산화물 제거용 폐탈질 촉매($V_2O_5/TiO_2$)의 비활성화 원인을 규명하고자 반응 활성 실험 및 물리 화학적 특성 분석을 수행하였으며, 다양한 재생방법을 통한 폐탈질 촉매의 재생효율을 연구하였다. 고정층 실험 결과 $260^{\circ}C$를 기준으로 약 60% 정도 질소산화물 제거 활성 차이를 보였으며, 허니컴 실험의 경우 1, 2-Dichlorobenzen (1, 2-DCB) 분해효율이 $200^{\circ}C$에서 약 14% 정도 차이가 나타났다. 또한 촉매의 비활성화 원인을 연구하기 위해서 신촉매와 폐촉매에 대하여 XRD, TGA, 그리고 ICP의 특성 분석을 실시한 결과 황산 암모늄염, 중금속(Pb, As 등), 전이금속(Fe 등), 알칼리 금속(Ca), 그리고 상전이가 촉매의 비활성화 원인으로 조사되었다. 또한, 폐촉매의 재생을 위해 다양한 방법으로 처리한 결과 수세과정을 배제한 공기분위기에서 열처리한 경우 우수한 재생효과를 나타내었다.