• Proceedings of the Korean Radioactive Waste Society Conference
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• 2004.06a
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• pp.353-354
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• 2004

사용후 핵연료의 조성을 분석하거나 또는 반사전자상과 2차 전자상 등으로 시료를 관찰하기 위해서는 핫셀(Hot cell)에 증착기(coater)를 설치하여 시료표면을 전도성 물질인 탄소 등으로 증착시켜야 한다. 그러나 원격조정기를(manipulator)를 이용하여 수행되는 핫셀에서의 증착작업은 사용후 핵연료 시험의 선진분석기술을 갖고 있는 원자력 선진국에서도 핫셀내에 설치되어 있는 증착기의 탄소봉을 교체하는 작업과 진공장치의 성능 유지가 까다로워 시료표면에 균질하게 전도성 물질을 증착시키는 작업에 많은 어려움을 겪고 있다. 본 연구는 통상적으로 이용되는 증착기를 사용하지 않고 Silver Paint를 사용하여 사용후 핵연료를 분석할 수 있는 새로운 방법에 대한 연구를 수행하였다. 산화물 핵연료는 전기전도도가 매우 낮아($3{\times}10^{-1}~4{\times}10^{-8}/ohm{\cdot}cm$)입사된 전자의 이동이 원활하지 못해 일어나는 들뜸(Charging)현상이 발생한다. 그러나 Silver Paint 에 사용후 핵연료를 접착하면 모세관(capillary)현상에 의해 시료 주위와 핵연료의 결정립계로 Silver가 스며들어 입사된 전자의 이동이 원활해져 전도성이 극히 낮은 시료의 분석이 가능하게 된다. 본 시험에 사용된 EPMA는 (Electron Probe Micro Analyzer, SX-50R, CAMECA, Paris, France) 고 방사능을 띤 조사 핵연료의 시험을 수행할 수 있도록 기기의 적절한 부위에 납과 텅스텐으로 차폐되어 시편의 방사능 세기가 $3{\times}10^{10}Bq$까지 시험 가능한 기기이다. 그림 1은 JAERI 에 설치 운영중인 증착기 설비 사진이다. 그림에서 핫셀에 설치된 증착기의 진공을 유지하기 위해 핫셀 벽을 관통하여 증착기 본체까지 연결된 배출관의 형상과 복잡한 주변장치들을 볼 수 있다. 그림 2는 비조사 핵연료 시편을 Silver Pain떼 접착한 사진이다. 그림은 시료주위와 시료 표면까지 Silver Paint가 도포된 모습을 보여주고 있다. 상용발전소에서 연소도가 50,000 Mwd/tU인 사용후 핵연료를 상기와 같은 방법으로 만든 시편의 표면을 관찰한 사진을 그림 3~8에 나타내었다. 그림 3은 핵연료 중앙부위의 결정립을 나타낸 그림이다. Silver Paint만으로 접착한 시료의 표면관찰 및 정량분석이 그림에서 보듯이 가능함을 확인하였다. 그림 4는 사용후 핵연료시료를 중앙부위에서 가장자리까지를 다섯 부위로 나누어 그 중 중앙부위(1/5) 지점의 입계 및 형상을 관찰한 사진이다. 결정립의 크기가 다른 부위보다 상대적으로 크고, 결정립에 생성된 기공이 발달되어 있음을 볼 수 있다. 그림 5와 6과 7은 중심부위와 rim부위 사이 지점을 관찰한 사진으로서 결정립과 기공의 분포가 비슷한 형상을 나타내고 있음을 관찰할 수 있었다. 그림 8은 rim 부위 사진으로 전형적인 rim 영역 현상을 관찰할 수 있었다. 표 1은 그림 2와 같이 비조사 산화물 핵연료를 Silver Paint로 접착한 시편을 정량 분석한 결과이다. 시편의 조성은 33.6 at% U, 66.4 at% O의 결과를 얻었다. 산화물 핵연료의 표면 관찰 및 정량 분석 시험시 시편 표면을 전도성 물질로 증착시키지 않고, Silver Paint 에 시편을 접착하는 방법으로도 만족한 시험 결과를 얻을 수 있었다.

• Membrane Journal
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• v.28 no.1
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• pp.55-61
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• 2018

With vigorous development of petroleum and chemical industry, emission of carbon dioxide has attracted tremendous attention globally due to global warming problem and abnormal climate change. To address these problems, in this study, a PEGBEM-g-POEM graft copolymer with high $CO_2$ affinity was synthesized and $CaCO_3$ was incorporated to form mixed matrix membranes (MMMs) for enhancement of $CO_2$ permeance. By varying the addition weight of $CaCO_3$ in MMMs, high separation performance of $CO_2$ over $N_2$ was obtained. At 50 wt% loading of $CaCO_3$, the greatest separation performance was obtained with an enhanced $CO_2$ permeance from 22.5 to 28.16 GPU and slightly increased $CO_2/N_2$ selectivity from 44.7 to 45.42. It resulted from the increased $CO_2$ solubility of MMMs due to specific interaction between $CaCO_3$ and $CO_2$ molecules. Upon excess loading of $CaCO_3$, MMMs exhibited loss of $CO_2$ separation performance due to the formation of interfacial defects. Based on this result, it is considered that the proper addition of $CaCO_3$ is crucial for improvement of $CO_2$ separation performance.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.12
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• pp.6602-6609
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• 2013

This study is expected to provide background data for establishing mitigation measures for malodor and for comparing complex odor criteria. The impact of malodor at the afflicted locations was analyzed using Industrial Source Complex Short Term 3 (ISCST3) model, which was recommended by the EPA. The Odor Emission Rates (ODR) for piglets and hogs were predicted based on the average, minimum, and maximum emission rates as classification. The forecasting result of the complex odor modelling of pigsty showed that tolerance limit was exceeded at an adjacent administration building, but tolerance limit was not surpassed at an afflicted location which was within 185m from the pigsty. The ISCST3 modelling of the satisfactory ODR for tolerance limit was accomplished at the administration building. From the prediction of this modelling, maximum emission rates based on 1hr at administration building were 10.59~52.93, 19.05~31.76, and 10.59 $OU/m^3/s/m^2$ at emission rates of 50%, 30%, and 10%. This emission rate was slightly higher than the tolerance limit of 10.00 $OU/m^3/s/m^2$. However, it was inferred that the tolerance limit could be satisfied if the emission rate of 10% was controlled.

• Korean Journal of Environmental Agriculture
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• v.11 no.3
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• pp.177-184
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• 1992

To investigate differences in lead contents of paddy soils and rice plants affected by municipal and industrial waste water pollution in Mangyeong River area, soil and plants samples were collected in 1982 and 1990 according to the distances from the main inlet source and depths of soil. Soil samples were extracted with ${4H-HNO}_3$ and plant sampler were digested with mixture of ${HNO}_3$ and ${HCIO}_4$ for analyzing by atomic absorption spectrophotometry. The Pb contents in soils ranged from 13.2 to 56.4 mg $kg^{-1}$. Average Pb level in 1990 was some higher than that in 1982. Variation of Pb content with the distances from the source of waste water showed decreasing tendency wish distances, and it was clearer in 1990 than in 1982. A significant correlation was observed between Pb contents in surface and in subsurface soil, between Pb content in soils and soil properties as clay, OM, and $Ca^{++}$ in 1982, and between Pb content in soils and contents of Cu and Zn in soils. The average Pb content in leaf sheath was 3.42 times of that in brown rice. Pb content in brown rice ranged from 3.1 to 10.4mg $kg^{-1}$.

• Korean Journal of Environmental Agriculture
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• v.13 no.1
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• pp.10-17
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• 1994

To investigate differences with the polluted sources on Cu contents in soils and paddy rices under water pollutions, soils with the distance, the surface(0-15㎝ depth) and subsurface(15-30㎝ depth) in 1982 and 1990, and rice plants at the soil sampling sites in 1990 were separately sample at Mangyeong River area under the influence of municipal and industrial waste water from Jeonju city. Soil samples were extracted with $4M-HNO_3$ and plant samples were digested with mixture of $HNO_3$ and $HClO_4$ for analyzing Cu, Cd, Zn, Pb by atomic absorption spectrophotometry. Cu contents in soils ranged from 5.20 to 71.70 mg $kg^{-1}$. Average Cu level in 1990 was higher than that in 1982. Variation of Cu content with the distances from the source of waste water in 1990 was more regularly decreased than that in 1982. A significant correlation was observed between Cu contents in leaf sheath of rice plant and Cu, Zn and Pb contents in soils. Cu contents in soil was correlated with Zn and Pb in soil at area affected by waste water, regardless of years and soil depths. Cu contents in brown rice ranged from 0.4 to 10 mg $kg^{-1}$, and it was the lowest in parts of rice plant, and Cu content in panicle axis was 2.3 times higher than that in brown rice.

• Journal of Energy Engineering
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• v.26 no.3
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• pp.51-63
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• 2017

Paris Agreement on Climate Change(2015) requires to reduce the greenhouse gas emission. One of the responses to the requirement is to change the proportion of power generation, which is summarized to the decrease in thermal power and the increase in new and renewable power. This article conducts a comparative analysis on the economic effects between thermal- and new and renewable- power generations, using the Input-Output Table from The Bank of Korea. The results of this analysis show that the new and renewable power generation has got the larger effects in production-inducing, value-added-inducing, employment-inducing, and supply-shortage scopes, while the smaller effect in price-pervasive scope than the thermal power generation. According to these results, the complex consideration should be taken into when the changes in power generation mix are tried. Especially, the political efforts to reduce the supply-shortage effect of new and renewable power and the price-pervasive effect of thermal power will be important.

• Journal of Korean Society of Forest Science
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• v.109 no.3
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• pp.300-312
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• 2020

The growing stocks of young forests that are less than10 years of age have been excluded from the Korean forest resource statistics, despite the existence of standing trees; however, sustainable forest management and carbon removals in the forestry section require complete information regarding forest resources. This study developed a method to estimate the growing stocks for young forests from National Forest Inventory (NFI) data. After reviewing previous research on growth characteristics for young forests, we conducted stem analysis of major species, and examined stand characteristics by site index, based on real yield tables. Our statistical analysis results showed that there were few standing trees with diameters at breast height (DBH) above 6 cm in young stands, and that it would have taken 12 years, on average, to reach 6 cm DBH. This suggests that mean tree height by diameter should be assessed at the root, in order to assess growing stocks for young stands through the NFI. Moreover, the database system should be improved to differentiate tree species, since diverse shrubs, including trees, have been surveyed.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.10
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• pp.725-731
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• 2016

This study numerically investigates the thermal performance of a 2.0-kW butane-based combustion heating system for an electric vehicle under cold conditions. The system is used for cabin space heating and coolant-based battery thermal management. ANSYS CFX 17 software was used for parametric analysis. The mass flow rates of cold air and coolant were varied, and their effects were compared. The numerical results were validated with theoretical studies, which showed an error of 0.15%. As the outside air mass flow rates were increased to 0.005, 0.01, and 0.015 kg/s, the cabin supply air temperature decreased continuously while the coolant outlet temperature increased. When the coolant mass flow rates were increased to 0.005, 0.01 and 0.015 kg/s, the air temperature increased while the coolant outlet temperatures decreased. The optimal mass flow rates are discussed in a consideration of the requirements for high cabin heating capacity and efficient battery thermal management.

• Proceedings of the Korea Water Resources Association Conference
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• 2018.05a
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• pp.390-390
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• 2018

산업화에 따른 온실가스 배출량 증가는 심각한 기후변화의 요인으로 작용하여 우리나라를 포함한 전세계는 이에 대응하고자 노력하고 있다. 지구온난화 및 엘리뇨 현상 등으로 인하여 가뭄, 홍수, 한파, 혹서 등의 재해와 기상이변이 속출하고, 최근 우리나라의 경우 매년 가뭄이 발생하고 있어 이에 대한 대책이 시급한 실정이다. 이에 가뭄의 대처방안에 대한 관심이 증대 되었고, 가뭄을 정량적으로 하는 연구들과 기후변화에 따른 가뭄 취약성 평가에 대한 연구들이 진행 되었다. 가뭄의 취약성 평가는 기후변화에 따른 가뭄 저감을 위한 목적에 따라 평가목적, 평가방법, 필요한 정보, 과정의 설계 불확실성에 대한 고려 등이 달라진다. 취약성 평가의 목적은 크게 기후영향평가, 적응정책의 자원배분을 위한 취약부문 및 지역 파악, 적응정책 개발을 위한 적응 대안 분석으로 나눌 수 있다. 취약성 평가의 목적이 취약성 유발요인에 관한 정보를 제공하여 어디에 적응 대책에 필요하고 효과적일 수 있는지 파악하는데 도움을 주는 것이라면, 취약성 결정요인에 대한 분석을 명료하고 상세하게 수행하는 것이 중요하다. 본 연구에서는 기후변화에 따른 농업용수의 취약성 평가지표를 개발하기 위하여 국내 외 취약성 평가 지표를 분석, 국내 농업기상 및 농업용수 등 관련 자료(1981 ~ 2015)의 조사 현황을 고려하여 취약성 평가지표(강우량, 증발산량, 경지면적, 저수용량, 용수로 통수능력, 수요량, 하천평수위)를 제시하고 국내 농업기상 및 농업용수 등 관련 자료의 조사 현황을 고려하여 대상지구인 충북 진천 무수 관개지구에 취약성 지표를 적용하였다. 강우의 증가는 가뭄 취약성에 긍정적 영향을 나타냈고, 증발산량의 증가는 부정적인 영향을 나타냈다. 경지면적의 감소는 소비수량이 증가하므로 가뭄 취약성에 긍정적인 영향을 나타냈고, 저수 용량의 감소는 홍수조절능력의 저하로 인해 부정적인 영향을 끼치고, 하천 홍수위의 변화는 가뭄에 영향을 미치는 요소 중의 하나로 홍수위가 높아지면 가뭄에 부정적인 영향을 나타냈다. 가뭄 취약성 지표들을 각각의 가중치를 합산한 결과, 1981년~2015(5년 분할) 무수지구의 가뭄 취약성 평가는 분석을 시작한 1981년부터 2015년 까지 안전과 우려가 반복 되는 것으로 나타났다. 연구대상지구의 농업기상 및 관련 자료들의 조사 기간이 길면 빈도별 신뢰성이 높아진다. 따라서 자료의 누적은 정확한 기후변화에 대한 이수 및 치수 취약성 평가 지표개발 및 평가 능력을 높여 줄 수 있을 것으로 판단된다.

• Journal of Korean Society of Rural Planning
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• v.27 no.3
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• pp.21-33
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• 2021

Rice straw management and winter crop cultivation are crucial components for the accurate estimation of paddy methane emissions. Field-based extensive investigation of paddy organic matter management requires enormous efforts however it becomes more feasible as drone technology advances. The objectives of this study were to identify paddy fields of straw application and winter crop cultivation using drone images and to apply for the estimation of yearly methane emission. Total 35 sites of over 150ha in area were selected nationwide as the study areas. Drone images of the study sites were taken twice during summer and winter in 2018 through 2019: Summer images were used to identify paddy cultivation areas, while winter images for straw and winter crop practices. Drone-image-based identification results were used to estimate paddy methane emission and compared with conventional method. As the result, mean areas for paddy, straw application and winter crop cultivation were 118.9ha, 12.0ha, and 11.3ha, respectively. Overall rice straw application rate were greater in Gyeonggi-do(20%) and Chungcheongnam-do(12%), while winter crop cultivation was greatest in Gyeongsangnam-do(30%) and Jeolla-do(27%). Yearly mean methane emission was estimated to be 226.2kg CH₄/ha/yr in this study and about 32% less when compared to 331.8kg CH₄/ha/yr estimated with the conventional method. This was primarily because of the lower rice straw application rate observed in this study, which was less than quarter the rate of 55.62% used for the conventional method. This indicates the necessity to use more accurate statistics of rice straw application as well as winter crop practices into paddy methane emission estimation. Thus it is recommended to further study to link drone technology with satellite image analysis in order to identify organic management practices at a paddy field level over extensive agricultural area.