• Journal of Electrochemical Science and Technology
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• 제6권4호
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• pp.111-115
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• 2015

In this work electrochemical oxidation of Ascorbic acid (AA) on the surface of Cobalt nano particle modified carbon paste electrode (CoNPsMCPE) was studied in alkaline media. CoNPs were green synthesized using Piper longum and a mixture of 5% (w/w) of it were made with carbon paste. CoNPs showed good electrocatalytic activity in alkaline media. Cyclic voltammetry (CV) and chronoamperometry (CA) were used to study the electrochemical performance of CoNPsMCPE. The number of monolayers on the surface of electrode was calculated as 1.08×10⁹ mol cm⁻² that is equal to that of metal Cobalt electrode. Diffusion coefficient of AA was determined using CA analysis which was equal to 1.5×10⁻⁶cm² s⁻¹.

• 한국재료학회지
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• 제28권11호
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• pp.633-639
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• 2018

In anion exchange membrane fuel cells, Pd nanoparticles are extensively studied as promising non-Pt catalysts due to their electronic structure similar to Pt. In this study, to fabricate Pd nanoparticles well dispersed on carbon support materials, we propose a synthetic strategy using mixed organic ligands with different chemical structures and functions. Simultaneously to control the Pd particle size and dispersion, a ligand mixture composed of oleylamine(OA) and trioctylphosphine(TOP) is utilized during thermal decomposition of Pd precursors. In the ligand mixture, OA serves mainly as a reducing agent rather than a stabilizer since TOP, which has a bulky structure, more strongly interacts with the Pd metal surface as a stabilizer compared to OA. The specific roles of OA and TOP in the Pd nanoparticle synthesis are studied according to the mixture composition, and the oxygen reduction reaction(ORR) activity and durability of highly-dispersed Pd nanocatalysts with different particles sizes are investigated. The results of this study confirm that the Pd nanocatalyst with large particles has high durability compared to the nanocatalyst with small Pd nanoparticles during the accelerated degradation tests although they initially indicated similar ORR performance.

• 한국토양비료학회지
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• 제44권4호
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• pp.581-590
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• 2011

Organic farming is rapidly expanding worldwide. Crop growth in organic systems greatly depends on the functions performed by soil microbes, and nutrient supply weed suppression by green manure crops input. Four red-pepper production systems were compared: 1) bare ground (conventional system); 2) hairy vetch monoculture; 3) rye monoculture; and 4) hairy vetch-rye mixture. Soil inorganic N reached the peak at 30 DAI and hairy vetch monoculture was the highest ($192mg\;kg^{-1}$) and soil total carbon was fluctuated sporadically during the experiment. Carbohydrate and phenolic compounds in soil kept significantly higher in green manure crops systems from 10 DBI to 30 DAI, however the level was the maximum at 10 DBI (carbohydrate) and 30 DAI (phenolic comounds). Incorporation of green manure crops residue enhanced soil microbial biomass C and N throughout the growing season except that MBN in rye was reduced after incorporation. Green manure crops systems suppressed weed occurrence and, in particular, it was prominent in rye monoculture. Mineral elements composition and production in red-pepper fruits were markedly decreased in green manure crops systems although hairy vetch monoculture has come close to bare ground (NPK-applied). Therefore, it was suggested that higher biomass production should be performed not only to improve soil quality and suppress weeds but to yield suitable red-pepper fruits in green manure crops-based organic farming.

• 청정기술
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• 제12권3호
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• pp.128-137
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• 2006

초임계이산화탄소 내에서 이온성액체의 부피 변화와 상온 이온성액체와 유기화합물의 혼합물이 두 상으로 분리되는 현상을 고압 view cell을 이용하여 측정하였다. 이온성액체(ionic liquid, IL)로는 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][$PF_6$])와 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][$BF_4$])를 사용하였으며, 유기화합물로는 methanol과 dimethyl carbonate를 사용하였다. 일정한 양의 [bmim][$PF_6$]에 대하여 유기화합물의 양을 증가시킴에 따라 상이 나누어지는 지점인 lower critical end point (LCEP) 압력이 감소하였다. 이온성액체의 수분함량이 증가함에 따라 LCEP가 높게 나타났으며, 일정량 이상의 수분이 함유되어 있으면 LCEP가 나타나지 않았다. LCEP는 같은 부피의 [bmim][$PF_6$]에서보다 [bmim][$BF_4$]에서 약 1.0 MPa 정도 높게 나타났으며, K-point는 이온성액체의 종류와 유기화합물의 양에 따라 거의 변화하지 않았다. 초기시료 중 이온성액체([bmim][$PF_6$])의 농도 (IL/(IL+MeOH))가 7.23 mol% 보다 크면 혼합물의 LECP에서 $L_1$의 부피가 $L_2$의 부피보다 크게 나타났으며, 반대로 작으면 작게 나타났다. 이산화탄소의 존재 하에서 이온성액체의 부피변화는 온도가 증가함에 따라 감소하였으며, 313.15 와 343.15 K 사이에서는 압력이 증가함에 따라 증가하여 300 bar에서는 원래 부피의 123~126 %가 되었다.

• 실내환경 및 냄새 학회지
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• 제17권4호
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• pp.372-380
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• 2018

To abate the problem of odor from restaurants, a hybrid adsorbent consisting of organic and inorganic materials was developed and evaluated using acetaldehyde as a model compound was deveioped and evaluated. Powders of activated carbon, bentonite, and calcium hydroxide were mixed and calcinated to form adsorbent structure. The surface area of the hybrid adsorbent was smaller than that of high-quality activated carbon, but its microscopic image showed that contours and pores were developed on its surface. To determine its adsorption capacity, both batch isotherm and continuous flow column experiments were performed, and these results were compared with those using commercially available activated carbon. The isotherm tests showed that the hybrid adsorbent had a capacity 40 times higher than that of the activated carbon. In addition, the column experiments revealed that breakthrough time of the hybrid adsorbent was 2.5 times longer than that of the activated carbon. These experimental results were fitted to numerical simulations by using a homogeneous surface diffusion model (HSDM); the model estimated that the hybrid adsorbent might be able to remove acetaldehyde at a concentration of 40 ppm for a 5-month period. Since various odor compounds are commonly emitted as a mixture when meat is barbecued, it is necessary to conduct a series of experiments and HSDM simulations under various conditions to obtain design parameters for a full-scale device using the hybrid adsorbent.

• 한국연소학회지
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• 제22권1호
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• pp.23-31
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• 2017

Large-scale fuel tanks emit massive amount of hardly-combustible VOC mixtures which are light hydrocarbon species in dilution with nitrogen and carbon dioxide. We have developed a lab-scale burner to combust those VOC mixtures by use of a turbulent partially-premixed flame as a pilot flame. For a higher HC treatment ratio, the mixture gases were reformed by a rotating arc plasma device. The results showed that the nitrogen mole fraction and the injecting speed of the VOC mixture influence on the performance of the burner. It was also found that the size of the pilot flame and the power supplied to the plasma device determine the overall HC treatment ratio and the concentrations of CO and NOx in the exhaust gas.

• 자원리싸이클링
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• 제11권1호
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• pp.32-36
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• 2002

이 연구는 돈분, 석고와 석탄화를 혼합물을 퇴비화한 것이다. 실험에 사용한 A 시료(PM : SD = 6 : 4)와 C 시료(PM : SD : GS : CFA = 6 : 2 : 1 : 1)를 사용하여 퇴비화 실험결과 A, C 시료의 초기 수분함량은 64, 50%이었고 온도, pH에서도 A시료와 비교했을 때 큰 차이는 없었으나 A,C 시료의 최종 TOC는 약 5550, 2900 mg/kg 이었다. 양이온 교환능은 A, C시료와는 크게 차이는 없었으나 CEC값으로 보아 숙성에 더 많은 시간이 필요할 것으로 생각된다. 그러나 석고와 석탄회 첨가는 돈분 퇴비화 과정에서 첨가제로서의 역할이 있음을 알 수 있었다.

• 한국환경과학회지
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• 제22권10호
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• pp.1263-1271
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• 2013

Graphene oxide (GO)-titania composites have emerged as an attractive heterogeneous photocatalyst that can enhance the photocatalytic activity of $TiO_2$ nanoparticles owing to their potential interaction of electronic and adsorption natures. Accordingly, $TiO_2$-GO mixtures were synthesized in this study using a simple chemical mixing process, and their heterogeneous photocatalytic activities were investigated to determine the degradation of airborne organic pollutants (benzene, ethyl benzene, and o-xylene (BEX)) under different operational conditions. The Fourier transform infrared spectroscopy results demonstrated the presence of GO for the $TiO_2$-GO composites. The average efficiencies of the $TiO_2$-GO mixtures for the decomposition of each component of BEX determined during the 3-h photocatalytic processes were 26%, 92%, and 96%, respectively, whereas the average efficiencies of the unmodified $TiO_2$ powder were 3%, 8%, and 10%, respectively. Furthermore, the degradation efficiency of the unmodified $TiO_2$ powder for all target compounds decreased during the 3-h photocatalytic processes, suggesting a potential deactivation even during such a short time period. Two operational conditions (air flow entering into the air-cleaning devices and the indoor pollution levels) were found to be important factors for the photocatalytic decomposition of BEX molecules. Taken together, these results show that a $TiO_2$-GO mixture can be applied effectively for the purification of airborne organic pollutants when the operating conditions are optimized.

• 한국지반공학회논문집
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• 제27권3호
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• pp.19-26
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• 2011

본 연구에서는 유기물이 혼합된 사질토와 점성토의 다짐특성을 파악하기 위하여, 사질토로는 풍화토를, 점성토로는 카오리나이트를, 유기물로는 석탄을 사용하여 혼합토를 만들고 다짐시험을 실시하였다. 또한 다짐시험시 계면활성제의 일종인 비눗물을 물 대신에 사용하여 다짐특성의 차이를 검토하였다. 유기질 풍화토에서 비눗물을 사용해 다짐시험을 하는 경우 물을 사용하여 다짐시험을 하는 경우와 마찬가지로 유기물함량이 클수록 최적함수비는 증가하고 최대건조단위중량은 감소하였다. 유기질 풍화토에서 작은 다짐에너지를 사용하는 경우에는 물 대신에 비눗물을 사용하면 다짐효과가 다소 증진하는 것으로 나타났다. 유기질 점성토에서는 비눗물을 사용해 다짐시험을 하는 경우 물을 사용하여 다짐시험을 하는 경우와 마찬가지로 유기물함량이 클수록 최적함수비는 감소하고 최대건조단위중량은 증가하였다. 유기질 점성토에서는 다짐에너지의 크기에 관계없이 물 대신에 비눗물을 사용하면 다짐효과가 다소 증진하는 것으로 나타났다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1990년도 추계학술대회 논문집 학회본부
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• pp.97-100
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• 1990

Diamond thin films were synthesized by the MPECVD (Microwave Enhanced Chemical Deposition) using the mixture of the hydrogen and organic compounds($CH_3COCH_3$, $CH_3OH$). In X-ray Diffraction, the d values of all the deposits on the Si substrates with the experimental conditions coincide with those of natural diamond in POD (Powder Diffraction Data). The changes of the morphology of all the deposits were examined by SEM. The amount of amorphous carbon or graphite in the diamond films were increased as the acetone concentration was increased. The morphology of the diamond particles can be changed from ball-like to euhedral by adding the small amount of the methanol in the reaction gases of the high acetone concentration.