• 한국항해항만학회지
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• 제31권8호
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• pp.671-674
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• 2007

본 논문에서는 ETC 시스템에서 다중반사로 인한 오신호 또는 시스템간의 간섭을 방지하기 위하여 사용될 전파흡수체를 설계 및 제작하였다. 자성손실 재료인 MnZn-ferrite, 도전손실 재료인 Carbon과 지지재인 CPE를 사용하여 조성비별로 전파흡수체 샘플을 제작하고, 측정된 샘플의 데이터로부터 최적의 조성비가 MnZn-ferrite : Carbon : CPE = 40 : 15 : 45 wt% 임이 확인되었다. 확인된 샘플로부터 재료정수 복소비유전율과 복소비투자율을 계산하여 시뮬레이션 하였으며, 이 결과를 토대로 전파흡수체를 실제 제작하여 전파흡수능을 분석한 결과 시뮬레이션과 실제측정 값이 거의 일치하는 것을 볼 수 있었다. 결과적으로 전파흡수체의 조성비 MnZn-ferrite : Carbon : CPE = 40 : 15 : 45 wt% 로 두께 3.38 mm, 주파수 5.8 GHz대에서 전파흡수능 20 dB 이상의 전파흡수체를 개발하였다.

• 한국산학기술학회논문지
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• 제14권9호
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• pp.4635-4642
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• 2013

화력발전소로부터 배출되는 이산화탄소를 분리하기 위하여 급수가 다른 아민을 혼합한 개선 흡수제를 개발하고자 하였다. 급수가 다른 1, 2, 3급 아민을 혼합한 후 이산화탄소 부분압에 따른 이산화탄소 흡수능을 조사하였다. 동일한 압력에서 이산화탄소 흡수능은 3DMA1P 30wt%>3DMA1P 27wt%+MEA 3wt%>3DMA1P 27wt%+DEA 3wt% 순으로 나타내었으며, 이는 3급인 3DMA1P에 2급인 DEA보다는 1급인 MEA를 혼합하는 것이 우수한 흡수능을 보이고 있다. 따라서 흡수능이 우수한 3급 아민에 흡수속도를 높이기 위하여 1급 아민을 혼합하는 것이 유리함을 알 수 있다. 최종적으로 준경험 기액 평형모델을 이용하여 실험 결과를 계산한 결과 실험치와 잘 일치하였다.

• Journal of Ecology and Environment
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• 제46권3호
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• pp.250-258
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• 2022

Background: To assess the carbon sequestration capacity and net ecosystem productivity (NEP) of Quercus glauca forests, we analyzed the net primary productivity (NPP), carbon storage, and carbon emission of soil in a Q. glauca forest on Jeju Island (South Korea) from 2016 to 2018. Results: The average carbon stock in the above- and below-ground plant biomass was 223.7 Mg C ha^-1, while the average amount of organic carbon fixed by photosynthesis was 9.8 Mg C ha^-1 yr^-1, and the average NPP was 9.6 Mg C ha^-1 yr^-1. Stems and branches contributed to the majority of the above- and below-ground standing biomass and NPP. The average heterotrophic carbon emission from the soil was 8.7 Mg C ha^-1 yr^-1, while the average NEP was 1.1 Mg C ha^-1 yr^-1. Although the carbon stock, carbon absorption, and soil respiration values were higher than those reported in other oak forests in the world, the NEP was similar or lower. Conclusions: These results indicator that Q. glauca forests perform the role of a large carbon sink through the CO₂ absorption in the plants in terms of carbon balance. And it is judged to be helpful as data for assessment of carbon storage and flux in the forests and mitigation of elevated CO₂ in the atmosphere.

• 한국산학기술학회논문지
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• 제11권11호
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• pp.4643-4648
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• 2010

본 논문에서는 주요 온실가스인 이산화탄소를 고압 환원 분위기인 연소전 조건에서 회수하기 위해 물리흡수제인 DMSO, Sulfone, PEG를 이용하여 이산화탄소 흡수특성을 조사하였다. 회분식 기-액 평형반응기를 이용하여 흡수반응온도 및 압력에 따른 이산화탄소 용해도와 물리흡수제의 재생성, 그리고 초기흡수특성을 연구하였다. 실험결과 PEG가 이산화탄소 용해도 및 초기 흡수능력이 가장 우수하였다. 그리고 PEG를 비롯한 물리흡수제가 다양한 흡수반응온도 및 압력에서 우수하게 재생됨을 확인할 수 있었다.

• Bulletin of the Korean Chemical Society
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• 제33권7호
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• pp.2325-2332
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• 2012

A series $[C_3Omim]$[X] of imidazolium cation-based ILs, with ether functional group on the alkyl side-chain have been synthesized and structure of the materials were confirmed by various techniques like $^1H$, $^{13}C$ NMR spectroscopy, MS-ESI, FTIR spectroscopy and EA. More specifically, the influence of changing the anion with same cation is carried out. The absorption capacity of $CO_2$ for ILs were evaluated at 30 and $50^{\circ}C$ at ambient pressure (0-1.6 bar). Ether functionalized ILs shows significantly high absorption capacity for $CO_2$. In general, the $CO_2$ absorption capacity of ILs increased with a rise in pressure and decreased when temperature was raised. The obtained results showed that absorption capacity reached about 0.9 mol $CO_2$ per mol of IL at $30^{\circ}C$. The most probable mechanism of interaction of $CO_2$ with ILs were investigated using FTIR spectroscopy, $^{13}C$ NMR spectroscopy and result shows that the absorption of $CO_2$ in ether functionalized ILs is a chemical process. The $CO_2$ absorption results and detailed study indicates the predominance of 1:1 mechanism, where the $CO_2$ reacts with one IL to form a carbamic acid. The $CO_2$ absorption capacity of ILs for different anions follows the trend: $BF_4$ < DCA < $PF_6$ < TfO < $Tf_2N$. Moreover, the as-synthesized ILs is selective, thermally stable, long life operational and can be recycled at a temperature of $70^{\circ}C$ or under vacuum and can be used repeatedly.

• 한국분말재료학회지
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• 제1권2호
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• pp.181-189
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• 1994

The compacts of pure and phosphorus-coated iron powder with 0~0.8%C were sintered at $1100^{\circ}C$ for 40 min. in cracked ammonia gas atmosphere. The tensile and impact strengths were measured and the relationship of the results with carbon content, phosphorus, quenching and tempering was investigated. The results obtained can be summarized as follows : (1) The tensile strength of sintered compacts increased slowly with carbon content. Increase in tensile strength by heat treatment was evident especially in the low carbon specimen. The specimen with phosphorus showed higher strength compared to pure iron compacts value. (2) No inflection point of elasticplastic deformation on stress-strain curve was observed in sintered steel. The elastic modulus of sintered steel had the same tendency as tensile strength. But the elongation showed the opposite tendency. (3) The impact absorption energy of sintered steel without addition of phosphorus decreased successively with carbon content and by quenching and tempering. On the contrary, addition of phosphorus resulted in an increase of the impact absorption energy. Quenching and tempering did not affect the impact energy especially in high carbon content. (4) The main fracture source was pore in specimen and the propagation of crack occured mostly along the grain boundaries. But the intragranular fracture was also observed in high carbon, quenched and tempered specimen, and especially in the specimen with phosphorus.

• 공업화학
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• 제10권2호
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• pp.177-182
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• 1999

대기중의 이산화탄소가 공기-아연전지에 미치는 영향을 검토하기 위하여 수산화칼륨 수용성 전해액을 공기와 접촉시킨 다음 시간의 경과에 따라 전해액중의 탄산칼륨 농도를 분석하여 전지 용량과의 관계를 규명하고자 하였다. 전해액은 공기와 접촉하는 시간이 경과함에 따라 대기중의 이산화탄소 흡수로 인하여 탄산칼륨의 농도가 증가하였으나 이에 비례하여 전지의 용량은 선형적으로 감소하였다. 이산화탄소의 흡수반응속도는 소수성 막의 세공크기가 주 인자로 작용하였으며, 세공크기를 조절한 소수성 막을 사용한 결과 이산화탄소 흡수로 인한 전지용량 열화현상을 현저히 감소시킬 수 있었다.

• Environmental Engineering Research
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• 제24권1호
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• pp.159-172
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• 2019

To investigate the influence of pollution events on the chemical composition and formation processes of aerosol particles, 24-h integrated size-segregated particulate matter (PM) was collected during the fall season at an urban site of Gwangju, Korea and was used to determine the concentrations of mass, water-soluble organic carbon (WSOC) and ionic species. Furthermore, black carbon (BC) concentrations were observed with an aethalometer. The entire sampling period was classified into four periods, i.e., typical, pollution event I, pollution event II, and an Asian dust event. Stable meteorological conditions (e.g., low wind speed, high surface pressure, and high relative humidity) observed during the two pollution events led to accumulation of aerosol particles and increased formation of secondary organic and inorganic aerosol species, thus causing $PM_{2.5}$ increase. Furthermore, these stable conditions resulted in the predominant condensation or droplet mode size distributions of PM, WSOC, $NO_3{^-}$, and $SO{_4}^{2-}$. However, difference in the accumulation mode size distributions of secondary water-soluble species between pollution events I and II could be attributed to the difference in transport pathways of air masses from high-pollution regions and the formation processes for the secondary chemical species. The average absorption ${\AA}ngstr{\ddot{o}}m$ exponent ($AAE_{370-950}$) for 370-950 nm wavelengths > 1.0 indicates that the BC particles from traffic emissions were likely mixed with light absorbing brown carbon (BrC) from biomass burning (BB) emissions. It was found that light absorption by BrC in the near UV range was affected by both secondary organic aerosol and BB emissions. Overall, the pollution events observed during fall at the study site can be due to the synergy of unfavorable meteorological conditions, enhanced secondary formation, local emissions, and long-range transportation of air masses from upwind polluted areas.

• 임산에너지
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• 제25권2호
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• pp.42-48
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• 2006

본 연구는 강원도 홍천군 운두령 일대에 설치된 잣나무 등 5개소 생장고정조사구를 대상으로 생장변화를 구명하고, 탄소저장량 및 흡수량을 산정하여 운두령 산림관리에 기초적인 자료를 제공하고자 하였다. 임분생장변화는 유령림인 잣나무, 낙엽송, 소나무 임분에서 연년수고생장과 흉고직경생장이 점진적으로 진행되었으며, 그 외 임분은 이들보다는 생장율이 낮은 것으로 나타났다. 직경급 분포 및 직경변화 예측에 있어서는 신갈나무와 자작나무 임분의 직경급분포는 현재와 유사할 것으로 예측되며, 다른 수종은 상위 직경급으로의 변화가 많을 것으로 예측되었다. 2005년 말 현재 운두령 모델림 내 총탄소량은 5,974천 탄소톤이고, 2005년도 한 해 동안 산림의 생장에 따른 총탄소량은 166,174 탄소톤이며, 순탄소흡수량은 155,481탄소톤으로 전년 대비 2,736탄소톤(1.8%)이 증가하였다. 결과적으로 운두령모델림은 온실가스 측면에서 볼 때 순흡수원으로 작용하고 있으며, 그 순흡수량도 최근 조금씩 늘어나고 있는 경향을 보이고 있다.

• 대기
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• 제21권3호
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• pp.301-309
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• 2011

In this study, we compared light-absorption properties of aerosols observed in East and South Asia from black carbon (BC) mass concentration, aerosol scattering (${\sigma}_s$) and absorption (${\sigma}_a$) coefficients measurements at four sites: Korea Climate Observatory-Gosan (KCO-G), Korea Climate Observatory-Anmyeon (KCO-A), Maldives Climate Observatory-Hanimaadhoo (MCO-H) and Nepal Climate Observatory-Pyramid (NCO-P). No significant seasonal variations of BC mass concentration, ${\sigma}_s$ and ${\sigma}_a$, despite of wet removal of aerosols by precipitation in summer, were observed in East Asia, whereas dramatic changes of light-absorbing aerosol properties were observed in South Asia between dry and wet monsoon periods. Although BC mass concentration in East Asia is generally higher than that observed in South Asia, BC mass concentration at MCO-H during winter dry monsoon is similar to that of East Asia. The observed solar absorption efficiency (${\alpha}$) at 550 nm, where ${\alpha}={\sigma}_a/({\sigma}_s+{\sigma}_a)$, at KCO-G and KCO-A is higher than that in MCO-H due to large portions of BC emission from fossil fuel combustion. Interestingly, ${\alpha}$ at NCO-P is 0.14, which is two times great than that in MCO-H and is about 40% higher than that in East Asia, though BC mass concentration at NCO-P is the lowest among four sites. Consistently, the highest elemental carbon to sulphate ratio is found at NCO-P.