• 신재생에너지
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• 제5권2호
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• pp.15-24
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• 2009

As new small scale LFG (landfill gas) energy project model which can improve economic feasibility limited due to the economy of scale, LFG-Microturbine combined heat and power system with $CO_2$ fertilization into greenhouses was proposed and investigated including basic design process prior to the system installation at Gwang-ju metro sanitary landfill. The system features $CH_4$ enrichment for stable microturbine operation, reduction of compressor power consumption and low CO emission, and $CO_2$ supplement into greenhouse for enhancement plant growth. From many other researches, high $CO_2$ concentration was found to enhance $CO_2$ assimilation (also known as photosynthesis reaction) which converts $CO_2$ and $H_2O$ to sugar using light energy. For small scale landfills which produce LFG under $3\;m^3$/min, among currently available prime movers, microturbine is the most suitable power generation system and its low electric efficiency can be improved with heat recovery. Besides, since its exhaust gas contains very low level of harmful contaminants to plant growth such as NOx, CO and SOx, microturbine exhaust gas is a suitable and economically advantageous $CO_2$ source for $CO_2$ fertilization in greenhouse. The LFG-Microturbine combined heat and power generation system with $CO_2$ fertilization into greenhouse gas to enhance plant growth is technologically and economically feasible and improves economical feasibility compared to other small scale LFG energy project model.

• 전기전자학회논문지
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• 제24권3호
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• pp.821-827
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• 2020

자동차에서 배출되는 배기가스가 대도시의 대기 오염원 중 큰 비중을 차지하고 있다. 특히 디젤이나 CNG버스 등 대중교통의 내연기관 차량은 매일 총 주행거리와 운행시간이 길고 차량 수량이 많기 때문에 배출가스 저감 대책이 시급하다. 본 논문에서는 실제로 전기버스의 도로 주행시험을 통한 연료소모율(km/kWh)을 측정하였다. 측정값을 근거로 버스 한 대당 내연기관과 전기버스에서 발생되는 CO₂배출량을 계산하였다. 전기버스를 시내버스로 대체할 경우 CNG버스 대비 예상되는 이산화탄소 저감 등 환경개선 효과와 더불어 전기버스로 대체가 확대될 경우 부가적인 효과를 분석하였다.

• 자원ㆍ환경경제연구
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• 제24권4호
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• pp.607-627
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• 2015

배출권 가격의 변동성은 기업의 온실가스 감축투자를 위한 의사결정 수립 시에 중요한 요인으로 고려된다. 본 논문의 목적은 우리나라 특성 상 재무구조가 연결된 발전사의 입장에서 배출권 가격의 불확실성을 고려하여 온실가스 저감투자의 실물옵션 가치를 평가할 수 있는 방법론을 제시하는 데 있다. 이윤함수가 선형적으로 분리불가한 경우에는 고전적인 실물옵션 기법으로 적정 투자임계 가격을 도출하는 것이 불가능하기 때문에, 몬테카를로 최소자승법을 적용하여 투자임계 가격을 산출하는 알고리즘을 제시하였으며, 가스, 석유, 석탄의 주요 화력발전원의 수치를 이용하여 투자임계 가격을 시뮬레이션 분석하였다. 배출권 가격으로 표시된 투자임계 가격이 가스와 석유가 석탄에 비해 현저히 낮은 것으로 평가되어, 온실가스 감축투자 측면에서 이들 화석연료가 석탄에 비해 상대적으로 유리한 것으로 나타났다.

• Carbon letters
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• 제25권
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• pp.14-24
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• 2018

Electrochemical properties and performance of composites performed by incorporating metal oxide or metal hydroxide on carbon materials based on graphene and carbon nanotube (CNT) were analyzed. From the surface analysis by field emission scanning electron microscopy and field emission transmission electron microscopy, it was confirmed that graphene, CNT and metal materials are well dispersed in the ternary composites. In addition, structural and elemental analyses of the composite were conducted. The electrochemical characteristics of the ternary composites were analyzed by cyclic voltammetry, galvanostatic charge-discharge tests, and electrochemical impedance spectroscopy in 6 M KOH, or $1M\;Na_2SO_4$ electrolyte solution. The highest specific capacitance was $1622F\;g^{-1}$ obtained for NiCo-containing graphene with NiCo ratio of 2 to 1 (GNiCo 2:1) and the GNS/single-walled carbon $nanotubes/Ni(OH)_2$ (20 wt%) composite had the maximum specific capacitance of $1149F\;g^{-1}$. The specific capacitance and rate-capability of the $CNT/MnO_2/reduced$ graphene oxide (RGO) composites were improved as compared to the $MnO_2/RGO$ composites without CNTs. The $MnO_2/RGO$ composite containing 20 wt% CNT with reference to RGO exhibited the best specific capacitance of $208.9F\;g^{-1}$ at a current density of $0.5A\;g^{-1}$ and 77.2% capacitance retention at a current density of $10A\;g^{-1}$.

• 대한약침학회지
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• 제25권4호
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• pp.382-389
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• 2022

Objectives: The Korean Industrial Standard (KS) for sterile acupuncture needles was established in 2009 based on research on the quality control of acupuncture needles. We aimed to determine the quality of acupuncture needles available in South Korea in 2021 by examining their surface condition and chemical composition using field-emission scanning electron microscopy (FE-SEM) and energy-dispersive X-ray spectroscopy (EDS). Methods: In South Korea, there are 23 brands of acupuncture needles, and we examined 10-15 needles from each brand, resulting in a total of 285 needles. The microstructures of the needles were assessed by SEM. Using SEM images, we evaluated the acupuncture needle tips for the following defects/aspects: scratches, lumps, detached coating, bent tip, and tip sharpness. EDS was used to determine the chemical composition of the selected acupuncture needles. Results: Overall, 88.4% of 285 needles were found to have at least one type of abnormality. The most frequently observed abnormalities were scratches and dents on the surface (68.1%), followed by detached coating (63.2%), and lumps (61.8%); blunt tips were observed in about 24% of them. Of 252 needles with at least one defect, 86.9% had two or more types of defects. The ratio of the number of needles with any defect to that of needles without any defect varied among brands, ranging from 50% to 100%. Regarding foreign materials, higher proportions of Si and O were observed on the needles, indicating incomplete or detached silicone coating. Conclusion: The quality of acupuncture needles varied among brands, suggesting that further improvements can be made through various inspection methods.

• 산업공학
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• 제24권2호
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• pp.156-163
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• 2011

The radiopharmaceutical synthesis for PET (positron emission tomography) is composed of chemical reactions using automated synthetical equipment. Due to the radioactive material, the automated equipment is being frequently developed to replace human operators who conduct dangerous, repetitive and dexterous operations. As to operation, the manipulating program is commonly coded using the spread sheet while the whole actuators are mapped in every step. The process map (program) is changed according to such parameters as temperature of reactor, keeping time, mixture sequence and amount of reagent. In cases of customizing the automated synthetical equipment or developing the new radiopharmaceuticals, lots of experiments should be conducted and the programming mistake is not allowed as it can lead abnormal control of the equipment to leak the radioactive materials. The exact process map has depended on trial and error manner. Thus, this study developed the methodology to tabulate the synthetical process to convert the process map automatically while the synthetical module formation is represented by a network model. The proposed method is validated using the actual radiopharmaceutical synthetical procedure.

• 한국분말재료학회지
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• 제24권6호
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• pp.457-463
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• 2017

Nanosized $Gd_2O_3:Eu^{3+}$ red phosphor is prepared using a template method from metal salt impregnated into a crystalline cellulose and is dispersed using a bead mill wet process. The driving force of the surface coating between $Gd_2O_3:Eu^{3+}$ and mica is induced by the Coulomb force. The red phosphor nanosol is effectively coated on mica flakes by the electrostatic interaction between positively charged $Gd_2O_3:Eu^{3+}$ and negatively charged mica above pH 6. To prepare $Gd_2O_3:Eu^{3+}$-coated mica ($Gd_2O_3:Eu/mica$), the coating conditions are optimized, including the stirring temperature, pH, calcination temperature, and coating amount (wt%) of $Gd_2O_3:Eu^{3+}$. In spite of the low luminescence of the $Gd_2O_3:Eu/mica$, the luminescent property is recovered after calcination above $600^{\circ}C$ and is enhanced by increasing the $Gd_2O_3:Eu^{3+}$ coating amount. The $Gd_2O_3:Eu/mica$ is characterized using X-ray diffraction, field emission scanning electron microscopy, zeta potential measurements, and fluorescence spectrometer analysis.

• 한국수소및신에너지학회논문집
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• 제24권6호
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• pp.524-534
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• 2013

Gasoline direct injection(GDI) engine has a high thermal efficiency, but it has a problem to increase carbon emissions such as soot and $CO_x$. In this study, the objective is to analyze numerically a problem for adding the hydrogen during the intake stroke so as to reduce the injected amount of gasoline in GDI engines. For selection of the base model, the cylinder pressure of simulation is matched to experimental data. The numerical analysis are carried out by a CFD model with the hydrogen addition of 2%, 3% and 4% on the volume basis. In the case of 3% hydrogen addition, the injected gasoline amount is only changed to match the maximum pressure of simulation to that of the base model for additional study. It is found that the combustion temperature and pressure increase with the hydrogen addition. And NO emission also increases because of the higher combustion temperature. $CO_x$ emissions, however, are reduced due to the decrease of injected gasoline amount. Also, as the injected gasoline amount is reduced for the same hydrogen addition ratio, the gross indicated work is no significant, But NO and $CO_x$ emissions are considerably decreased. On the order hand, $CO_x$ emissions of two cases are more decreased and their gross indicated works are higher obtained than those of the base model.

• KIEAE Journal
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• 제13권4호
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• pp.11-19
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• 2013

The purpose of this study is to establish the assessment baseline of $CO_2$ emissions from building operations in the view of GHG reduction policy in Korea. The assessment baseline of $CO_2$ emissions shall be used in GHG policy and Carbon Credits in building sectors, but the assessment baseline has not been studied enough or established yet. Also, $CO_2$ emissions from building operations will be variable according to the building occupancy. Therefore the baseline will be different and this study aimed at the establishment of the assessment baseline for residential apartments and office buildings firstly. After reviews of BEER and international standards for building $CO_2$ emissions such as ISO and UNEP-SBCI documents, the analysis of BEER certification data has been pursued for 292 residential apartment complexes and 65 office buildings in South Korea during 2004~2012. As analysis results, the assessment baseline was set to 23.03 $kg{\cdot}CO_2/m^2{\cdot}yr$ or 1.95 $t{\cdot}CO_2/unit{\cdot}yr$ for residential apartment complexes, and 95.91 $kg{\cdot}CO_2/m^2{\cdot}yr$ for office buildings according to the BEER certification basis. Additional assessment baselines were calculated according to year basis, region basis, public and private basis, and GHG policy basis. Finally, the established baseline for residential apartment complexes has been applied for the pilot project in M district, Seoul, and showed 24.97% reduction rate according to the BEER certification basis.

• 한국환경농학회지
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• 제24권2호
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• pp.117-122
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• 2005

논 토양으로부터 발생된 지구온난화 가스의 배출 제어 기술을 구명하기 위하여 논 토양에서 가축분퇴비 및 토양개량제 시용에 따른 온실가스 배출 양상을 검토하였다. 축분퇴비 시용에 따른 $CH_4$ 배출량은 우분퇴비 처리구가 331 kg $ha^{-1}$로 가장 많았으며, 돈분퇴비 시용구는 282 kg $ha^{-1}$, 계분퇴비 시용구는 294 kg $ha^{-1}$이었다. $N_2O$ 배출량은 계분퇴비 시용구가 1.78 kg $ha^{-1}$, 돈분퇴비 시용구가 1.78 kg $ha^{-1}$, 우분퇴비 시용구가 1.60 kg $ha^{-1}$이었다. 반면에 볏짚을 시용한 처리구의 $N_2O$ 배출량은 1.44 kg $ha^{-1}$이었다. 지구온난화 지수(global warming potential : GWP)는 우분퇴비 처리구가 7,447 kg $ha^{-1}$로 가장 많았으며, 돈분퇴비 시용구는 6,474 kg $ha^{-1}$, 계분퇴비 시용구는 6,726 kg $ha^{-1}$ 그리고 볏짚시용구는 6,956 kg $ha^{-1}$이었다. 토양개량제 시용에 의한 온난화 가스 배출시험에서 석회 시용구의 $CH_4$ 배출량은 다근 처리에 비해 373 kg $ha^{-1}$로 가장 많았으며, 규산 시용구는 264 kg $ha^{-1}$, 인공제올라이트 시용구는 239 kg $ha^{-1}$ 그리고 볏짚 시용구는 310 kg ha-1이었다. $N_2O$ 배출량은 석회 시용구가 1.49 kg $ha^{-1}$, 규산 시용구가 1.40 kg $ha^{-1}$, 인공제올라이트 시용구가 1.38 kg $ha^{-1}$이었다. 지구온난화지수(GWP)는 석회 처리구가 8,295 kg $ha^{-1}$, 규산 시용구는 5,978 kg $ha^{-1}$, 인공제올라이트 시용구는 5,447 kg $ha^{-1}$ 그리고 볏짚 시용구는 6,956 kg $ha^{-1}$이었다.