• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 1999.04b
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• pp.375-380
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• 1999

In order to improve the optical properties of high yield pulp, bleached chemi-thermo-mechanical pulp (BCTMP) was produced from CTMP of Betula maximowicziana Regel by two staged ozone-hydrogen peroxide bleaching. This pulp was used for the evaluation of the improvement of optical properties, chemical characteristics of lignin in fiber, and the relationship between lignin and optical properties in fiber cell wall. By hydrogen peroxide treatment, the brightness was improved, but the post color number (PC No.) was not. There was little improvement on optical properties by ozone treatment, but his could be solved by using two staged ozone-hydrogen peroxide bleaching. The hydrogen peroxide treatment did not make nay change on chemical characteristics of lignin in cell wall, but by ozone treatment, it was found that the non-aromatic conjugated structure was existed in the surface of cell wall, but this could be removed by hydrogen peroxide treatment in two staged ozone-hydrogen peroxide treatment. Therefore, the optical properties was significantly improved due to the removal of non-aromatic conjugated structure.

• Transactions of the Korean hydrogen and new energy society
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• v.15 no.2
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• pp.119-128
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• 2004

DME(Dimethyl Ether) was directly produced from the synthesis gas using the slurry phase reactor. The catalyst for DME production prepared two types (A type; Cu:Zn:Al=57:33:10, B type; Cu:Zn:Al=40:45:15, molar ratio). It was evaluated for the effect of the reaction medium oil using the small size slurry phase reactor. DME production yield and the methanol selectivity decreased in the order: n-hexadecane oil> mineral oil> therminol oil. The long-term test of DME production was carried out using A and B type catalyst, and n-hexadecane oil and mineral oil, respectively. It was confirmed that the use of A type for the catalyst and n-hexadecane for the reaction medium oil was very useful for the viewpoint of the DME production form the synthesis gas.

• Journal of the Korean Society for Heat Treatment
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• v.17 no.6
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• pp.356-364
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• 2004

The hydrides in cladding affect the corrosion and tensile properties. In this study corrosion and tensile properties were evaluated with varying the hydrogen concentration. The charged hydrogen contents were ranged from 200 to 1000 ppm. The corrosion rate in water and LiOH solution increases with the hydrogen concentration. The hydride did not affect the corrosion mechanism in the pre-transition region, but in the post-transition region the corrosion rate was accelerated. Cladding E contained higher Niobium content was slowly accelerated compared with other claddings. The yield and ultimate strengths were independent on the hydrogen content. However, the total elongation decreased gradually with increasing the hydrogen content. SEM observation of fracture surface showed that an average of depth of voids decreased with increasing the hydrogen content and small secondary crack are observed.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.21 no.1
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• pp.1-6
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• 2012

This paper presents a stress safety of a composite pressure cylinder for a hydrogen gas vehicle. The composite pressure cylinder in which is composed of an aluminum liner and carbon fiber wound layers contains 104 liter hydrogen gas, and is compressed by a filling pressure of 70 MPa. The FEM computed results are analyzed based on the US DOT-CFFC basic requirement for a hydrogen gas cylinder and KS B ISO specification. The FEM results indicate that the stress, 255.2 MPa of an aluminum liner is sufficiently low compared with that of 272 MPa, which is 95% level of a yield stress for aluminum. Also, the composite layers in which are wound on the surface of an aluminum cylinder are safe because the stress ratios from 3.46 to 3.57 in hoop and helical directions are above 2.4 for a minimum safety level. The proposed composite pressure cylinder wound by carbon fibers is useful for 70 MPa hydrogen gas vehicles.

• Transactions of the Korean hydrogen and new energy society
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• v.14 no.2
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• pp.105-113
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• 2003

The pyrolysis for production of hydrogen and high quality carbon black from natural gas were studied. The reactivities in tubular reactor and FVR(free volume reactor) for the methane pyrolysis were compared, in order to prevent the formation of undesirable carbon product such as pyrocarbon, the FVR was designed. The hydrogen yield and the formation of carbon black from methane pyrolysis in this reactor were investigated at temperature range between 1443 and 1576K. From the result of TEM (transmission electron microscopy) analysis, it was confirmed that the CFC(catalytic filamentous carbon) was formed without pyrocarbon.

• Korean Journal of Materials Research
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• v.27 no.6
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• pp.318-324
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• 2017

In this study, two Fe-30Mn-0.2C-(1.5Al) high-manganese steels with different surface conditions were hydrogen-charged under high temperature and pressure; then, tensile testing was performed at room temperature in air. The yield strength of the 30Mn-0.2C specimen increased with decreasing surface roughness(achieved via polishing), but that of the 30Mn-0.2C-1.5Al specimen was hardly affected by the surface conditions. On the other hand, the tendency of hydrogen embrittlement of the two high-manganese steels was not sensitive to hydrogen charging or surface conditions from the standpoints of elongation and fracture behavior. Based on the EBSD analysis results, the small decrease in elongation of the charged specimens for the Fe-30Mn-0.2C-(1.5Al) high-manganese steels was attributed to the enhanced dislocation pile-up around grain boundaries, caused by hydrogen.

• Applied Chemistry for Engineering
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• v.33 no.3
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• pp.322-327
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• 2022

Fucoidans were degraded by hydrogen peroxide under the electron beam (2.5 MeV) with various radiation doses (5 kGy, 10 kGy, 15 kGy, and 20 kGy) at room temperature. The degradation property was analyzed with a gel permeation chromatography (GPC-MALLS) method. An average molecular weight of fucoidan decreased from 99,956 at the irradiation dose of 0 kGy to 6,725 at the irradiation dose of 20 kGy. The solution viscosity of fucoidans showed a similar pattern to the molecular weight change. The number of chain breaks per molecule (N) increased with increasing the irradiation dose and concentration of hydrogen peroxide. The radiation yield of scission value markedly increased with increasing the irradiation dose up to 15 kGy. Also a 10% hydrogen peroxide concentration was more efficient than that of 5%. The structures of degraded fucoidan samples were studied with Fourier transform infrared spectroscopy (FT-IR). The results showed that the degradation process did not significantly change the chemical structure or the content of sulfate group. The sulfur content of each sample was determined with an Elemental Analyzer. With increasing the concentration of hydrogen peroxide, the ratios of sulfur/carbon, hydrogen/carbon, and nitrogen/carbon slightly decreased. The antioxidant activities of fucoidans were investigated based on hydroxyl radical scavenging activities. The ability of fucoidan to inhibit the hydroxyl radical scavenging activity was depended on its molecular weight.

• Transactions of the Korean hydrogen and new energy society
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• v.22 no.5
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• pp.714-720
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• 2011

Ethanol was used as reducing agent to remove $NO_x$ exhaust from the stationary source. Pre-treatment with sulfuric acid over $Ag/Al_2O_3$ catalyst was dedicated to overcome the $SO_2$ poisoning effect. The $NO_x$ reduction experiment was performed under the simulated condition of power plant The increased surface area with higher CPSI devoted to increase de-$NO_x$ yield. De-$NO_x$ yield of the $NO_x$ exhaust containing 20 ppm of $SO_2$ increased after acid treatment with 0.7% $H_2SO_4$ over 4.0% $Ag/Al_2O_3$, where the increased dispersion of Ag found from the results of XRD and XPS was the dominant factor for the increased de-$NO_x$ yield. However, the reason for the decreased de-$NO_x$ yield with the acid treatment of higher concentration (1.0% and 2.0%) of $H_2SO_4$ was found to be due to the formation of $Ag_2SO_4$ crystallites found from XRD result. Acid-treated $Ag/Al_2O_3$ catalyst showed maximum de-$NO_x$ yield at higher temperature than non-treated $Ag/Al_2O_3$ catalyst did.

• Journal of the Korean Institute of Gas
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• v.5 no.1
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• pp.15-20
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• 2001

The microwave plasma and catalytic reaction have been employed to investigate the activation of methane to hydrogen and higher hydrocarbons at low gas temperature. The catalytic activity of Fe, Ni, Pt Pd metal catalysts were also studied in this reaction system. With increasing plasma power at a $CH_{4}$ flow rate of 20 ml/min, C2+ products increased from 29 to $42\%$, whereas hydrogen from 60 to $65\%$. When catalysts were loaded below the plasma region, the selectivitity of ethylene md acetylene increased but the yield of C2+ products remained constant. The usage of ECR electric fie3d and Pd-Ni bimetal catalyst produced a minimum C2+ yield of $64\%$.

• Transactions of the Korean hydrogen and new energy society
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• v.26 no.3
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• pp.199-205
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• 2015

Organic wastes such as food waste (FW), livestock wastewater (LW), and sewage sludge (SWS) can produce hydrogen ($H_2$) by anaerobic acid fermentation. Expecially, FW which has high carbohydrate content produces $H_2$ and short chain fatty acids by indigenous $H_2$ producing microorganisms without adding inoculum, however $H_2$ production rate (HPR) and yield have to be improved to use a commercially available technology. In this study, LW was mixed to FW in different ratios (on chemical oxygen demand (COD) basis) as an auxiliary substrate. The mixture of FW and LW was pretreated at pH 2 using 6 N HCl for 12 h and then fermented at $37^{\circ}C$ for 28 h. HPR of FW, 254 mL $H_2/L/h$, was increased with the addition of LW, however, mixing ratio of LW to FW was reversely related to HPR, exhibiting HPR of 737, 733, 599, and 389 mL $H_2/L/h$ at the ratio of FW:LW=10:1, 10:2, 10:3, and 10:4 on COD basis, respectively. Maximum HPR and $H_2$ production yield of 737 $H_2/L/h$ and 1.74 mol $H_2/mol$ hexoseadded were obtained respectively at the ratio of FW:LW=10:1. Butyrate was the main organic acid produced and propionate was not detected throughout the experiment.