• Journal of the Korean Institute of Landscape Architecture
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• v.42 no.5
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• pp.64-72
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• 2014

This study quantified the storage and annual uptake of carbon by apple trees in orchards as a production-type greenspace, and computed the annual carbon emissions from apple cultivation. Tree individuals in the study orchards were sampled to include the range of stem diameter sizes. The study measured biomass for each part including the roots of sample trees through a direct harvesting method to compute total carbon storage per tree. Annual carbon uptake per tree was quantified by analyzing the radial growth rates of stem samples at ground level. Annual carbon emissions from management practices such as pruning, mowing, irrigation, fertilization, and use of pesticides and fungicides were estimated based on maintenance data, interviews with managers, and actual measurements. Regression models were developed using stem diameter at ground level (D) as an independent variable to easily estimate storage and annual uptake of the carbon. Storage and annual uptake of carbon per tree increased as D sizes got larger. Apple trees with D sizes of 10 and 15 cm stored 9.1 and 21.0 kg of carbon and annually sequestered 1.0 and 1.6 kg, respectively. Storage and annual uptake of carbon per unit area in study orchards were 3.81 t/ha and 0.42 t/ha/yr, respectively, and annual carbon emissions were 1.30 t/ha/yr. Thus, the carbon emissions were about 3 times greater than the annual carbon uptake. The study identified management practices to reduce the carbon footprint of production-type greenspace, including efficient uses of water, pesticides, fungicides, and fertilizers. It breaks new ground by including measured biomass of roots and a detailed inventory of carbon emissions.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.8
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• pp.5728-5735
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• 2015

This study attempts to verify the applicability of ceramic membrane as a separator by comparing the power generation characteristics in single-chamber MFCs using ceramic membranes to those in the MFCs using nafion membrane. The generated power in MFCs by using acetate as a substrate was more stable than that by using formate, propionate and butyrate, respectively. It was shown that the generated power by using formate substrate in MFCs was unstable and a little higher than that by using acetate, and the power generated by using propionate and butyrate were lower than that by using acetate. In order to find out the Pt catalyst effect, it was compared the power generated in MFCs using Pt-coated carbon cloth as electrode to that power using normal carbon cloth. The power generated in MFCs using Pt-coated carbon cloth as electrode was 1.2 times higher than that using normal carbon cloth. The Pt-coated carbon cloth was about 5 times more expensive than normal carbon cloth. It is suggested that both power generation efficiency and cost together should be considered in selecting electrodes of MFCs. It was found that the ceramic membrane was superior to nafion membrane by comparing to the power generation characteristics obtained. It was shown that average voltage values were $523.67mV{\pm}49.41mV$ by using synthetic wastewater, in MFCs of ceramic membrane as a separator. While average voltage values were $424.09mV{\pm}79.95mV$ by using synthetic wastewater, in MFCs of nafion membrane as a separator. The organic removal efficiency, 41.7% by using ceramic membrane was a little bit higher than 40.8% by using nafion membrane. This research implies ceramic membrane can be a valid alternative to nafion membrane as a separator when considering the power generation and the efficiency of organics removal.

• Journal of the Korea Organic Resources Recycling Association
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• v.23 no.3
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• pp.85-92
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• 2015

For concerning the climate change issues, the carbon sequestration and importance of soil organic matter are receiving high attention. To evaluate carbon sequestration in soil is important to determine the soil organic carbon (SOC) fractions such as WESOC (Water extractable soil organic carbon), and $CO_2$ emission by soil microbial respiration. However, the analyses for those contents are time-consuming procedure. There were studied the feasibility of MIRS (Mid-Infrared Spectroscopy), which has short analysis time for determining the WESOC and an incubated carbon in this study. Oven-dried soils at $100^{\circ}C$ and $350^{\circ}C$ were scanned with MIRS and compared with the chemically analyzed WESOC and cumulative carbon dioxide generated during 30, 60, 90, and 120 days of incubation periods, respectively. It was observed that an optimized determination coefficient was 0.6937 between WESOC and untreated soil processed by spectrum vector normalization (SNV) and 0.8933 between cumulative $CO_2$ from 30 days incubation and soil dried at $350^{\circ}C$ after subtracting air-dried soil processed by 1st derivatives. Therefore, it was shown that Quantification of soil organic carbon fractions was possibility to be analyzed by using MIRS.

• Journal of Korea Water Resources Association
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• v.52 no.11
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• pp.917-929
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• 2019

Denitrification in streams is of great importance because it is essential for amelioration of water quality and accurate estimation of $N_2O$ budgets. Denitrification is a major biological source or sink of $N_2O$, an important greenhouse gas, which is a multi-step respiratory process that converts nitrate ($NO_3{^-}$) to gaseous forms of nitrogen ($N_2$ or $N_2O$). In aquatic ecosystems, the complex interactions of water flooding condition, substrate supply, hydrodynamic and biogeochemical properties modulate the extent of multi-step reactions required for $N_2O$ flux. Although water flow in streambed and residence time affect reaction output, effects of a complex interaction of hydrodynamic, geomorphology and biogeochemical controls on the magnitude of denitrification in streams are still illusive. In this work, we built a two-dimensional water flow channel and measured $N_2O$ flux from channel sediment with different bed geomorphology by using static closed chambers. Two independent experiments were conducted with identical flume and geomorphology but sediment with differences in dissolved organic carbon (DOC). The experiment flume was a circulation channel through which the effluent flows back, and the size of it was $37m{\times}1.2m{\times}1m$. Five days before the experiment began, urea fertilizer (46% N) was added to sediment with the rate of $0.5kg\;N/m^2$. A sand dune (1 m length and 0.15 m height) was made at the middle of channel to simulate variations in microtopography. In high- DOC experiment, $N_2O$ flux increases in the direction of flow, while the highest flux ($14.6{\pm}8.40{\mu}g\;N_2O-N/m^2\;hr$) was measured in the slope on the back side of the sand dune. followed by decreases afterward. In contrast, low DOC sediment did not show the geomorphological variations. We found that even though topographic variation influenced $N_2O$ flux and chemical properties, this effect is highly constrained by carbon availability.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2011.05a
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• pp.141-141
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• 2011

DLC(Diamond Like Carbon) 박막은 높은 경도, 낮은 마찰계수, 내화학성 등의 우수한 트라이볼로지적 특성을 가지고 있기 때문에 다양한 산업분야에서 적용되고 있다. 이러한 DLC 박막은 합성기구나 구조의 관점에서 몇 가지 다른 이름으로 불려지기도 한다. 밀도와 경도가 높기 때문에 경질탄소(Hard Carbon)라고도 불려지며, 수소를 함유한 경우에는 수소함유 비정질 탄소(Hydrogenated Amorphous Carbon)이라는 이름이 사용되며, 고밀도 탄소(Dense Carbon) 또는 고밀도 탄화수소(Dense Hydrocarbon)라고 불리기도 한다. 이렇듯 DLC 박막은 합성방법에 따라 함유된 수소와 탄소의 결합구조의 차이가 있다. 수소 함유한 DLC 박막은 20~50%까지 수소를 함유하며, DLC막의 기계적, 광학적, 전기적 특성들이 수소함량과 밀접한 관계를 가지고 있는 것으로 알려져 있다. 그러나 함유된 수소가 $300^{\circ}C$ 이상의 온도에서는 쉽게 결합에서 이탈되면서 흑연화와 더불어 마찰마모시 코팅층의 파손이 발생한다고 보고되고 있고, 또한 수소량이 증가함에 따라 DLC 박막의 경도는 감소하게 되는데, 이는 수소에 의해 dangling bond가 Passivation되면 탄화수소의 3차원적인 Crosslinking은 그만큼 감소하게 되기 때문이라고 알려져 있다. 본 연구에서는 PECVD를 이용하여 여러 가지 공정에 따른 DLC 박막을 증착시켰으며, 수소함유량에 따른 DLC막의 구조와 그에 따른 경도 변화를 살펴보았다. FTIR(Furier Transform Infrared Spectroscopy)과 Raman Spectroscopy을 이용하여 DLC막의 수소의 결합상태를 관찰하였으며, Nano Indentation을 사용하여 미소경도를 측정하였고, FE-SEM을 이용하여 표면과 단면을 관찰하였다. 막의 두께 측정에는 ${\alpha}$-Step을 사용하였으며, Ball-on-Disk 타입의 Tribo-meter을 이용하여, 모재의 경도에 따른 마찰계수 변화를 관찰하였다.

• Proceedings of the Korea Contents Association Conference
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• 2017.05a
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• pp.253-254
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• 2017

미연탄소의 함유량이 많은 플라이애시를 사용한 시멘트의 경우 공기량이 저하되며, 슬럼프의 확보를 위해 AE제와 같은 혼화제의 사용을 요구한다. 이러한 미연탄소를 제거하기 위해 저온 플라즈마를 이용한 표면 개질에 관한 연구가 진행되었으나, $O_2$를 사용하는 플라즈마의 경우 $O_3$를 생성하는 문제가 발생한다. 따라서 본 연구에서는 플라즈마를 대신에 아크방전을 이용하여 플라이애시 내의 미연탄소를 제거해 표면을 개질하는 기술에 관한 기초적 연구를 진행하였다. 그 결과, 아크방전을 통해 플라이애시의 표면을 개질할 시 플라이애시의 물리적 특성이 개선되며, 이를 이용한 시멘트경화체의 강도도 향상되는 것을 알 수 있었다.

• Journal of the Korean Society of Marine Environment & Safety
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• v.17 no.2
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• pp.173-178
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• 2011

Marine TEMA heat exchanger is the equipment to transfer the heat energy through both fluids that are enclosed separately by applying conduction and convection phenomena for a large vessels, Especially for heat exchanger working under the high temperature and high pressure, the expansion ratio should be taken into account other than under the low temperature and low pressure. This study was tried to find out the ideal expansion ratio through analyzing the elasto-plastic stress behavior of deformation while tubes are expanded with the finite element methods.

• Fire Science and Engineering
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• v.21 no.2 s.66
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• pp.30-35
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• 2007

The flame retardancies by the addition of metal powder and flame retardant were evaluated to present as the fundamental data to decrease the fire hazard of polymers and life losses by suffocation and poisoning. For this study, the experiments of flame retardancy were conducted as follows : weight loss rate using thermogravimetric analysis, the measurement of the limiting oxygen index(LOI) and char yield. And smoke mass concentration and CO yield were measured. Acrylonitrile butadiene styrene containing metal powder and flame retardant reduced weight loss rate and increased LOI and char yield with the decreased smoke mass concentration and CO yield. It was found that the most effective complex was tricresyl phosphate-Mo complex.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 1999.10a
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• pp.264-265
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• 1999

대기오염의 주원인이 되는 VOC는 자동차, 건축 등 도장분야에서 '96년기준으로 343,258톤/년이 발생되고 있으며 '94년 기준으로 국내 5개 정유회사의 정제 및 저장시설에서 년간 7,687톤, 출하시설에서 21,889톤이 배출되고 있으며 그 밖에 350개사의 페인트 제조업회사와 비디오 테이프 등의 세정공장에서도 상당량이 발생되는 등 매년 증가 일로에 있다.(중략)

• 한국신재생에너지학회:학술대회논문집
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• 2010.11a
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• pp.154.2-154.2
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• 2010

상대적으로 이산화탄소 배출량이 적으며, 기존의 천연가스를 대체할 수 있고, 21세기 신 에너지원으로 기대되고 있는 메탄 하이드레이트(Methane hydrate)는 태평양과 대서양의 대륙사면 및 대륙붕, 남극대륙의 주변해역 등지에서 자연적으로 발생한 메탄 하이드레이트의 분포가 확인되었으며, 그 매장량의 1조 탄소톤 이상으로 기존 화석연료의 매장량이 5천억 탄소톤, 대기중의 메탄가스가 3억 6천만 탄소톤임을 고려할 때 2배에 이르는 막대한 양이라고 보고하였다. 따라서 메탄 하이드레이트는 화석에너지를 대체할 수 있는 차세대 청정 에너지 또는 대체 에너지원으로서의 무한한 잠재력을 가지고 있어 새로운 에너지분야로 크게 주목을 받고 있다. 또한 하이드레이트는 $172m^3$의 메탄가스와 $0.8m^3$의 물로 분해된다. 만약, 특성을 역으로 이용하여 산업적으로 고체화 수송을 할 경우 화수송보다 18-24%의 비용절감이 이루어질 것으로 예상되어진다. 그러나 메탄 하이드레이트를 인공적으로 만들경우 물과 가스의 반응율이 낮아 하이드레이트 형성시간이 상당히 길고 가스 충진율도 낮다. 따라서 본 연구에서는 하이드레이트를 빨리 만들며 가스 충진율도 증가시키기 위하여 증류수와 다공성물질이며 나노세공(Nano pore)을 가지고 있는 제올라이트를 증류수에 첨가하고, 초음파 분산하여 만든 혼합유체를 메탄가스와 반응시켜 하이드레이트 형성 실험을 수행하여 비교 분석하였다. 그 결과 0.01 wt% 제올라이트 혼합유체에서 증류수보다 하이드레이트가 훨씬 빨리 생성되었으며, 메탄가스소모량은 ${\Delta}T_{subc}$=0.5K에서 약 4배 높음을 보였다.