• Journal of the Korean GEO-environmental Society
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• v.4 no.3
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• pp.61-67
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• 2003

A new precess which consists of pre-dewatering device, post composting for solid phase and post sequencing batch reactor(SBR) for liquid phase was designed. Nitrogen in supernatants of dewatering device was removed by sequencing batch reactor. Experiments were carried out to investigate the SBR operation modes such as fill ratio, SRT, and operation cycle. The optimum fill ratio, SRT and aeration/non-aeration time were 1/12, 15days, and 2hr aeration / 1hr non aeraion, respectively. Methanol as an external carbon source increased denitrification when step feeding method was applied, not single feeding method.

• Journal of the Korea Organic Resources Recycling Association
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• v.22 no.3
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• pp.33-40
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• 2014

This study were conducted to evaluate the N mineralization and nitrification rates and to estimate the losses of total carbon and nitrogen by runoff water in soils cooperated with organic composts and bio-char during corn cultivation. For the experiment, the soil texture used in this study was clay loam, and application rates of chemical fertilizer and bio-char were $230-107-190kg\;ha^{-1}$($N-P_2O_5-K_2O$) as recommended amount after soil test and 0.2% to soil weight. The soil samples were periodically taken at every 15 day intervals during the experimental periods. The treatments were consisted of cow compost, pig compost, swine digestate from aerobic digestion system, and their bio-char cooperation. For N mineralization and nitrification rates, it was shown that there were generally low in the soil cooperated with bio-char as compared to the only application plots of different organic composts except for 47 days after sowing. Also, they were observed to be highest in the application plot of swine digestate from aerobic digestion system. For loss of total carbon by run-off water, it was ranged from 1.5 to $3.0kg\;ha^{-1}$ in the different organic compost treatment plots. However, Loss of total carbon with bio-char could be reduced at $0.4kg\;ha^{-1}$ in PC treatment plot. Also, with application of bio-char, total nitrogen was estimated to be reduced at 4.2 (15.1%) and $3.8(11.8%)kg\;ha^{-1}$ in application plots of pig compost and swine aerobic digestate, respectively.

• Korean Journal of Environmental Biology
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• v.22 no.1
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• pp.93-100
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• 2004

The content of nutrients such as organic carbon, nitrogen, phosphorus and potassium accumulated on soil layers in Quercus mongolica forest of Mt. Songnisan National Park located at central part of Korea was measured, and then the decomposition constants and decay times of the nutrients were also calculated by the negative coefficience model(O1son,1963). The quantities of organic carton of L-layer, F-layer, H-layer and $A_1$-layer of the forest stand were 231.25 g $m^{-2}$, 291.50 g $m^{-2}$,166.91 g$m^{-2}$ and 174.51 g $m^{-2}$, respectively. The content of organic carbon and nitrogen contained in L-layer and F-layer showed large quantity than those of other layers. The large amount of phosphorus and potassium was observed at the B-layer and $A_1$-layer. On the other hand, the decomposition constants(k) of soil organic matter were as follows : organic carbon (k = 0.3657), nitrogen (k = 0.3319), phosphorus (k = 0.2050), and potassium (k = 0.0934) and the decay times needed to 99% decomposition of nutrients in soil organic matter were as follows: that is, organic carton, nitrogen, phosphorus and potassium was 13.94 years, 15.18 years, 24.79 years, and 55.11 years, respectively. By the application of Turbo Pascal Program on the inflowed and outflowed nutrients to the forest stand,87.67% (714.84 g $m^{-2}$) of organic carbon inflowed was decomposed and 81.62% (1,594.62 g $m^{-2}$) of organic carbon accumulated was decomposed. And 84.98% of nitrogen inflowed was decomposed and 70.26% of nitrogen accumulated was also decayed.50.00% of phosphorus input and 40.31% of potassium input were decomposed, and 38.40% of phosphoyus and 33.03% of potassium accumulated were also decayed, respectively. Therefore, it is suggested that Quercus mongolica forest surveyed in the present study is maintaining in steady state because input and output amounts of nutrients is shown a similar pattern.

• Journal of the Korean Vacuum Society
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• v.20 no.6
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• pp.436-441
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• 2011

Metal coating with several nanometer thickness was applied on the carbon nanotubes (CNTs) in order to improve electron emission characteristics and emission reliability for the potential applications in the area of various electron sources and displays. CNTs were grown on the 2-nm thick Invar (52% Fe, 42% Ni, 6% Co alloy)-catalized Si substrate by using plasma-enhanced chemical vapor deposition at $450^{\circ}C$. In order to reduce the spatial density of densely packed CNTs, as-grown CNTs were partly etched back by $N_2$ plasma and subsequently coated with 5~150 nm thick Ti by a sputtering method. 5 nm thick Ti-coated CNTs produced four times higher emission current density at the electric field of 6 V/${\mu}m$ and much lower emission current fluctuation, compared with the as-grown CNTs. These improved emission properties are mainly due to not only the work function of Ti (4.3 eV) lower than that of pristine CNTs (5 eV), but also lower contact resistance and better adhesion between CNT emitters and substrate accomplished by Ti coating.

• Proceedings of the Materials Research Society of Korea Conference
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• 2012.05a
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• pp.94.1-94.1
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• 2012

폴리페닐카보실란은 페닐그룹을 포함하고 있는 카보실란계 고분자로서 열분해 후 과량의 탄소를 함유할 수 있는 세라믹 전구체이다. 카보실란계열의 고분자는 산화특성이 있어 SiOC 코팅 용도에도 사용되고 있는데, 폴리페닐카보실란은 free 탄소를 함유하는 SiOC:C 필름을 형성할 수 있다. SiOC 코팅 전구체로는 일반적으로 실리카졸, 실라잔 계열의 고분자, 실록산 계열의 고분자가 사용되고 있으나, 폴리페닐카보실란의 경우 상기 전구체에 비하여 보관 안정성 및 뛰어난 부착특성을 나타낸다. 기존 연구에서는 폴리페닐카보실란으로부터 형성된 SiOC:C 필름의 저유전막, 산화방지막, 분진방지막 등의 응용성에 대하여 고찰한 바 있다. 폴리페닐카보실란은 열처리 온도 영역에 따라 응용 분야가 달라질 수 있는데, 이에 본 연구에서는 각 열처리 온도 영역에 따라 형성되는 SiOC:C 필름의 구조적 변화를 고찰하였다. 필름 형성은 20 % 폴리카보실란 용액을 스핀코팅하고 대기상에서 경화를 실시하였으며, 질소 분위기에서 400 ~ 1200 도 범위에서 열처리하였다. 이렇게 얻어진 300 nm 두께의 필름은 XPS 표면분석과 FT-IR, Solid-NMR을 이용하여 C-Si-O 네트워크 형성의 거동을 확인하였으며, 800 도 이상에서 나타나는 특징적인 free 탄소는 Raman을 이용하여 확인하였다.

• Resources Recycling
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• v.4 no.1
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• pp.25-30
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• 1995

In the preparatIon of reclaimed aluminium lllgot from alumimum scrap, the aluminium recovery was studied a as a function of the preliminary treatment of samples, addition of flux and melting atmosphere. AI dross is produced by an oxidation reaction at the surface of liquid metal. The recovery of AI metal increases u up to maximum 95% by adding salt up to 7%, The recovery of AI metal in the compacted chip bale without oil removal mcrease about 14% compared io non-compacted chip. In the case of the AI seed melting process, the recovery of Al metal of the crushed and compacted chip hale is 97%, In meltmg of alumimum scrap under the atmosphere of carbon and nitrogen gas, the recovery of AI metal increase, but it is decreased when the mixture of salt and carbon powder is added excessively.

• Korean Chemical Engineering Research
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• v.50 no.5
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• pp.885-889
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• 2012

In this study, amine and metal oxide additives were investigated to improve $CO_2$ adsorption capacity of activated carbons (ACs). The characteristics of surface modified ACs were studied by X-ray photoelectron spectroscopy (XPS), $N_2$ adsorption, X-ray diffraction (XRD), and BET. Amine surface treatment decreased specific surface area and pore volume of ACs, but increased alkalinity by the incorporated nitrogen functional groups. Adsorption capacities of amine functionalized ACs was larger than original ACs, because basic group which can react with $CO_2$ was grafted on the ACs surface. Presence of copper oxides on ACs also enhances the carbon dioxide adsorption. The copper oxides could increase the adsorption rate of carbon dioxides due to the acid-base interaction (or electron acceptor-donor interaction). It was found that copper oxide loading was a promising method to improve the $CO_2$ adsorption capacity of ACs.

• KSBB Journal
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• v.9 no.4
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• pp.365-371
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• 1994

The effects of ratios of initial concentration of carbon source to the initial concentration of nitrogen source in the fermentation media on both the yields of PHB fermentation variables and the accumulation of poly-${\beta}$-hydroxybutyric acid(PHB) were investigated. The fermentation media were composed of the combination of varing glucose concentrations, 10, 20, 25, 30, 40, $50g/\ell$ and the NH4Cl concentrations 0.33, 0.4, 0.5, 1.5, 3, $5g/\ell$. The yield of biomass on glucos, Yx/s, decreased very slowly according to the increase of the ratio of C to N. And the yield became constant at 0.35(g biomass/g glucose) with the ratio higher than 70. The yield of residual biomass, Yx/s, also decreased with the ratio of C to N and finally showed a constant value of 0.065(g residual biomass/g glucose) when the ratio was higher than 65. In accordance with the augmentation of the ratio, the yield of PHB, YPHB/S, however, increased and showed the maximum value of 0.35 (g PHB/g glucose) between 40 and 60 of the ratio. The maximum yield of PHB to the change of biomass, YPHB/S, was 0.87(g PHB/g biomass), and the yie1d YPHB/RX, was 4.2(g PHB/g residual biomass). The maximum accumulation percent of PHB to the final biomass was 81% when the ratio was higher than 67.

• Journal of Korean Society of Forest Science
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• v.111 no.2
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• pp.234-241
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• 2022

We performed this study to determine the foliar nutrient concentration and the nutrient stocks of restoration areas and adjacent Pinus densiflora S. et. Z. (red pine) stands in opencast kaolinite mines in Sancheong-gun, Gyeongsangnam-do, southern Korea. We chose six sites to determine foliage nutrient concentrations and the nutrient stocks of soils (0-10 cm depth). The dominant vegetation planted in restoration areas comprised Quercus acutissima Carruth., P. koraiensis S. et. Z., Festuca arundinacea Schreb., and Lespedeza cuneata G. Don. Invading vegetation in the restoration areas comprised Alnus incana (L.) Medik., Robinia pseudoacacia L., and Lespedeza spp., among others. The carbon and nitrogen stocks at 10 cm soil depth were significantly higher in the red pine stands than those in the restoration areas, whereas those of phosphorus, potassium, and magnesium were not significantly different between the two areas. However, calcium stocks were significantly higher in the restoration areas than in the red pine stands. Nitrogen concentration in foliage was higher in L. cuneata (20.28 mg N g^-1) than that in F. arundinacea (5.67 mg N g^-1), whereas potassium concentration was twice as high in F. arundinacea (18.8 mg K g^-1) as that in L. cuneata (9.07 mg K g^-1). Foliar nitrogen concentrations in invasive vegetation such as A. incana, R. pseudoacacia, and Lespedeza spp. were twice or four times higher than those of Q. acutissima and P. koraiensis. Our results indicate the development of suitable vegetation and soil amendment treatments to improve poor soil environmental conditions in restoration areas are necessary following opencast kaolinite mining.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.11
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• pp.1174-1179
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• 2005

Up-flow sludge blanket(USB) reactors were used to investigate the effects of N/C(${NO_3}^--N/COD$) ratio on simultaneous denitrification and methanogenesis processes. Without nitrate feeding, 84% of the influent COD was converted into methane. With the increase of N/C ratio, nitrogen gas increased while methane production decreased and stopped finally at the N/C ratio over 0.20. Influent nitrate was completely denitrified into nitrogen gas while nitrate removal efficiency dropped below 40% at N/C ratio of 0.40 because of deficiency in organic carbon. Fraction of COD utilized by denitrification increased at higher N/C ratios. Methanogenesis started to be effected at N/C ratio of 0.05, which could explain the competition for organic carbon between these microorganisms such as denitrifiers and methanogens, rather than inhibitory effect of nitrate and its intermediates. Critical N/C ratio for simultaneous denitrification and methanogenesis was found to be 0.20. Influent COD was removed over 92% by denitrification, methanogenesis and other biochemical reactions including cell growth at these N/C ratios.