• Carbon letters
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• v.26
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• pp.66-73
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• 2018

We assessed the effects of combining bio-char with straw residue mulching on the loss of soil soluble nutrients and citrus yield in sloping land. The two-year study showed that straw residue mulching (ST) and bio-char application combined with straw residue (ST+BC) can significantly reduce soil soluble nutrient loss when compared with the control treatment (CK). The comparative volume of the soil surface runoff after each of the treatments was as follows: CK > ST > ST + BC. Compared with the CK, the runoff volume of the ST was reduced by 13.6 % and 8.5 % in 2014 and 2015, respectively. Compared with the CK, combining bio-char with the ST application reduced the loss of soluble nitrogen and improved the soil total nitrogen content reaching a significant level in 2015. It dramatically increased the soil organic matter content over the two year period (36.3% in 2014, 50.6% in 2015) as well as the carbon/nitrogen ratio (C/N) (16.6% in 2014 and 39.3% in 2015). Straw mulching combined with bio-char showed a trend for increasing the citrus yield.

• Fibers and Polymers
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• v.1 no.2
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• pp.97-102
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• 2000

Pitch precursors were synthesized from coal tar(CT) and pyrolysis fuel oil(PFO, petroleum residue oil) at relatively low temperature of $250^{\circ}$, in the presence of horontrifluorideidiethyletherate complex(BFDE) as a catalyst and nitrobenzene(NB) as a co-catalyst. The softening point, nitrogen content and carbon yield increased with an increase of concentration of NB. The pitch precursors with good spinnability were prepared by removing the volatile components through $N_2$ blowing. The precursor pitches were spun through a circular nozzle, stabilized at $310^{\circ}$ and finally carbonized at $1000^{\circ}$. The optically anisotropic structure formed at the absence of NB was changed into isotropic structure, showing a decrease in size of the flow domain. The hollow carbon fiber could be prepared in the process of stabilization. The results proposed that the morphology of carbon materials could be controlled by changing the concentration of catalyst and/or co-catalyst and/or stabilization condition that affect on the mobility of molecules during carbonization.

• Korean Journal of Materials Research
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• v.23 no.9
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• pp.510-516
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• 2013

Fly ash is one of the aluminosilicate sources used for the synthesis of geopolymers. The particle size distribution of fly ash and the content of unburned carbon residue are known to affect the compressive strength of geopolymers. In this study, the effects of particle size and unburned carbon content of fly ash on the compressive strength of geopolymers have been studied over a compositional range in geopolymer gels. Unburned carbon was effectively separated in the $-46{\mu}m$ fraction using an air classifier and the fixed carbon content declined from 3.04 wt% to 0.06 wt%. The mean particle size ($d_{50}$) decreased from $22.17{\mu}m$ to $10.79{\mu}m$. Size separation of fly ash by air classification resulted in reduced particle size and carbon residue content with a collateral increase in reactivity with alkali activators. Geopolymers produced from carbon-free ash, which was separated by air classification, developed up to 50 % higher compressive strength compared to geopolymers synthesized from raw ash. It was presumed that porous carbon particles hinder geopolymerization by trapping vitreous spheres in the pores of carbon particles and allowing them to remain intact in spite of alkaline attack. The microstructure of the geopolymers did not vary considerably with compressive strength, but the highest connectivity of the geopolymer gel network was achieved when the Si/Al ratio of the geopolymer gel was 5.0.

• Carbon letters
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• v.5 no.3
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• pp.127-132
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• 2004

Chop molding composites and 2D carbon/carbon composites were manufactured by hot press molding method. Phenol resin of novolac type was used for matrix precursor and PAN-based carbon, PAN-based graphite and pitch-based carbon fiber were used for reinforcement and boron oxide was used for oxidation retardant. All of the composites were treated by $2000^{\circ}C$ and $2400^{\circ}C$ graphitization process, respectively. After graphitization process, amount of a boron residue in carbon/carbon composites is much according to irregularity of used raw materials. Under the presence of boron in carbon/carbon composites, catalytic effect of boron was a little at $2000^{\circ}C$ graphitization temperature. However, it was quite at $2400^{\circ}C$ graphitization.

• Journal of Microbiology and Biotechnology
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• v.30 no.11
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• pp.1688-1696
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• 2020

Soil physical and chemical characteristics, soil potential denitrification rates (PDR), community composition and nirK-, nirS- and nosZ-encoding denitrifiers were studied by using MiSeq sequencing, quantitative polymerase chain reaction (qPCR), and terminal restriction fragment polymorphism (T-RFLP) technologies base on short-term (5-year) tillage field experiment. The experiment included four tillage treatments: conventional tillage with crop residue incorporation (CT), rotary tillage with crop residue incorporation (RT), no-tillage with crop residue retention (NT), and rotary tillage with crop residue removed as control (RTO). The results indicated that soil organic carbon, total nitrogen and NH₄⁺-N contents were increased with CT, RT and NT treatments. Compared with RTO treatment, the copies number of nirK, nirS and nosZ in paddy soil with CT, RT and NT treatments were significantly increased. The principal coordinate analysis indicated that tillage management and crop residue returning management were the most and the second important factors for the change of denitrifying bacteria community, respectively. Meanwhile, this study indicated that activity and community composition of denitrifiers with CT, RT and NT treatments were increased, compared with RTO treatment. This result showed that nirK, nirS and nosZ-type denitrifiers communities in crop residue applied soil had higher species diversity compared with crop residue removed soil, and denitrifying bacteria community composition were dominated by Gammaproteobacteria, Deltaproteobacteria, and Betaproteobacteria. Therefore, it is a beneficial practice to increase soil PDR level, abundance and community composition of nitrogen-functional soil microorganism by combined application of tillage with crop residue management.

• 한국기계연구소 소보
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• s.15
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• pp.37-46
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• 1985

Properties of Precursor pitch derived from petroleum residue were studied physical and chemical analysis method for investigation of production of pitch fiber. For preparing of those precursor pitches it was carried out a temperature and time variation experiment i reactor. It was demonstrated the precursor pitch prepared in this study to have a similar properties to Ashland precursor pitch capable of bulk mesophase formation from the results of the basic analysis, that is, molecular weight distribution, coking yield, carbon content, chemical composition, etc.

• Journal of Pharmaceutical Investigation
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• v.9 no.1
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• pp.1-6
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• 1979

This report is carried out pharmaceutical properties for the mosquito coil made of Ginseng leaf and the residue after extraction of Ginseng root. This experimental results are: Loss on drying of Insam (Ginseng) mosquito coil powder is average 8.31%, ash content of the powder is average 9.51% and burning time of Insam mosquito coil is aprroximately 36 minutes per gram. The contents of carbon monoxide and carbon dioxide on burning of mosquito coil are as same as following: Insam mosquito coil A brand mosquito coil B brand mosquito coil Allethrin in a piece of Insam mosquito coil was stable under the experimental conditions. CO (ppm) 360 540 760 $CO_2(%)$ 0.052 0.076 0.066 Allethrin in a piece of Insam mosquito coil was stable under the experimental conditions.

• New & Renewable Energy
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• v.5 no.2
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• pp.9-14
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• 2009

Automobile Shredder Residue (ASR) is very appropriate in a gasification melting system. Gasification melting system, because of high reaction temperature over than $1,350^{\circ}C$, can reduce harmful materials. To use the gasification processes for hydrogen production, the high concentration of CO in syngas must be converted into hydrogen gas by using water gas shift reaction. In this study, the characteristics of shift reaction of the high temperature catalyst (KATALCO 71-5M) and the low temperature catalyst (KATALCO 83-3X) in the fixed - bed reactor has been determined by using simulation gas which is equal with the syngas composition of gasification melting process. The carbon monoxide composition has been decreased as the WGS reaction temperature has increased. And the occurrence quantity of the hydrogen and the carbon dioxide increased. When using the high temperature catalyst, the carbon monoxide conversion ratio ($1-CO_{out}/CO_{in}$) rose up to 95.8 from 55.6. Compared with average conversion ratio from the identical synthesis gas composition, the low temperature catalyst was better than the high temperature catalyst.

• Journal of Korean Society of Forest Science
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• v.102 no.1
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• pp.82-89
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• 2013

Harvest is one of the major disturbances affecting the soil carbon (C) dynamics in forests. However, researches on the long-term impact of periodic harvest on the soil C dynamics are limited since they requires rigorous control of various factors. Therefore, we adopted a modeling approach to determine the long-term impacts of harvest interval, harvest intensity and post-harvest residue management on soil C dynamics by using the Korean Forest Soil Carbon model (KFSC model). The simulation was conducted on Pinus densiflora S. et Z. stands in central Korea, and twelve harvest scenarios were tested by altering harvest intervals (50, 80, and 100-year interval), intensities (partial-cut harvest: 30% and clear-cut harvest: 100% of stand volume), and the residue managements after harvest (collection: 0% and retention: 100% of aboveground residue). We simulated the soil carbon stock for 400 years for each scenario. As a result, the soil C stocks in depth of 30 cm after 400 years range from 50.3 to 55.8 Mg C $ha^{-1}$, corresponding to 98.1 to 108.9% of the C stock at present. The soil C stock under the scenarios with residue retention was 2.5-11.0% higher than that under scenarios with residue collection. However, there was no significant impact of harvest interval and intensity on the soil C stock. The soil C dynamics depended on the dead organic matter dynamics derived from the amount of dead organic matter and growth pattern after harvest.

• Fibers and Polymers
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• v.2 no.4
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• pp.178-183
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• 2001

A pitch precursor for a general purpose carbon fiber was prepared by condensation of pyrolized fuel oil (petroleum residual oil) with bromine under nitrogen blowing. such a condensation raised the softening point of the pitch from 4$0^{\circ}C$ to $265^{\circ}$ with a yield of 43%. The pitch precurosr showed an enhanced aromaticity and enlarged molecular size, which led to a reduction in molecular mobility and optical isotropy. The precursor was spun into fibers of $20\mu\textrm{m}$ diameter at a take-up speed of 700m/min. The fiber was stepwise stabilized in air and carbonized in Ar gas to obtain an isotropic carbon fiber. The carbon fiber exhibited tensile strengths of 500-800 ㎫though the fiber was formed via a crude method. The electric conductivity of the carbon fiber was relatively high, 2.2$\times$$10^2$S/cm, sufficient to be used as electrode materials.