• Journal of the Korean Institute of Gas
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• v.18 no.5
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• pp.40-46
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• 2014

The hydrogen embrittlement degree of 5 type high strength DP steel charged with hydrogen by electrochemical method was evaluated by small punch test(SP test). After SP test, SP absorbed energy was remarkably decreased from 363 kgf-mm to 209 kgf-mm with increasing hydrogen charging time from 5hr to 50hr at DP5 specimen under the $200mA/cm^2$ current density condition. It was investigated that the decrease of hydrogen charging amount and SP absorbed energy according to the increase of current density and hydrogen charging time had a linear relationship. And it also investigated that the change of bulb height appeared by the SP test was decreased from 1.79mm to 1.59mm with the hydrogen charging conditions. It was supposed that it could be used as indicator of the evaluation of hydrogen embrittlement because of the similar trend of the formal results of SP absorbed energy. From the SEM observation of fracture area by crack in bulb, the morphology of fracture surface according to increasement of the hydrogen charging amount was varied with the cleavage mode.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.40 no.2
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• pp.57-64
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• 2008

In general, the entire of paper mulberry bark, which is not cut into pieces with an appropriate length, have been used in the pulping. This kind of pulping method couldn't accomplish the improvement of beating and sheet forming efficiency. For this reason, we investigated the effects of the cutting length of paper mulberry bast fiber on pulping and Hanji (Korean traditional paper) properties, in order to develop high quality Hanji manufacturing process. The cutting length variation of paper mulberry white bast did not great effects on pulp yields. The pulp yields based on pulping methods were sulfomethylated pulping av. 57.4%, alkali-hydrogen peroxide pulping av. 55.4%, and alkaline pulping av. 53.5% respectively. The optical properties such as brightness, opacity, scattering coefficient, and absorption coefficient were slightly improved by the increase of paper mulberry white bast cutting length. The increase of paper mulberry white bast cutting length resulted in poor sheet formation. Physical properties such as breaking length, TEA, tear index, burst index, and folding endurance were slightly improved by the increase of cutting length. The modified pulping processes, which used sulfomethylated method and alkali-hydrogen peroxide method, showed better pulp and sheet properties than conventional alkaline pulping.

• Biotechnology and Bioprocess Engineering:BBE
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• v.8 no.1
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• pp.54-57
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• 2003

H$_2$-producing bacteria were isolated from anaerobic granular sludge. Out of 72 colonies (36 grown under aerobic conditions and 36 under anaerobic conditions) arbitrarily chosen from the agar plate cultures of a Suspended sludge, 34 colonies (15 under aerobic conditions and 19 under anaerobic conditions) produced H2 under anaerobic conditions. Based on various biochemical tests and microscopic observations, they were classified into 13 groups and tentatively identified as follows: From aerobic isolates, Aeromonar spp. (7 strains), Pseudomonas spp. (3 strains), and Vibrio spp. (5 strains); from anaerobic isolates, Actinomyces spp. (11 Strains), Clostridium 5pp. (7 strains). and Porphyromonas sp. When glucose was used as the carbon substrate, all isolates showed a similar cell density and a H$_2$ production yield in the batch cultivations after 12 h (2.24-2.74 OD at 600 nm and 1.02-1.22 mol H$_2$/mol glucose, respectively). The major fermentation by-products were ethanol and acetate for the aerobic isolates, and ethanol, acetate and propionate for the anaerobic isolates. This study demonstrated that several H$_2$ producers in an anaerobic granular sludge exist En large proportions and their performance in terms of H$_2$ production is quite similar.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2006.06b
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• pp.365-372
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• 2006

In this paper, the possibility of statistical modeling from the pulp and peroxide bleaching condition variables to predict optical properties of a bleached chemimechanical pulp used in a newsprint paper machine at Mazandaran Wood and Paper Industries Company (MWPI) was studied. Due to the variations in the opacity and the brightness of the bleached pulp at MWPI and to tackle this problem, it was decided to study the possibility of modeling the bleaching process. To achieve this purpose, Multi-variate Regression Analysis was used for model building and it was found that there is a relationship between independent variables and pulp brightness as well as pulp opacity, consequently, two models were constructed. Then, model validation was carried out using new data set in the bleaching plant at MWPI to test model predictive ability and its performance.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.32 no.1
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• pp.78-85
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• 2000

Due to environmental proessures there is increasing use of hydrogen peroxide as a total or partial substitute for chlorine based bleaching agents within ECF or TCF sequences. However, to aceive satifactory brightness using peroxide alone, stages having a combination of high temperature, pressure, pH or residence time are required. It may also have negative impact on fiber quality . Therefore, it would be of advantage if vertain means could be found to make hydrogen peroxide more effective in bleacing , via shortening treaction time and allevaiating the need for such forcing reaction conditions. This can be achieve by converting the peroxide in-situ to stronger oxidant through the use of 손 bleach activator. In this study to investigate the influence of additives, such as tetraacetylethylenediamine (TAED) and Molybdate (MO) . addition on peroxide bleaching were carried out. Under alkaline conditions the bleching additives. TAED and Mo. can react H2O2 to form peracetic acid and peroxomolybdate respectively and these generated activators can improve deliginification,. The activators make it possible to bleach the pulp efficiently at low temperature in the range 50 to 7$0^{\circ}C$. Also, addition of TAED and Mo is an environmentally friendly way of enhancing the performance of peroxide bleaching can be incorporated into TCF and ECF sequences.

• Clean Technology
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• v.21 no.2
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• pp.108-116
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• 2015

Hydrogen sulfide and ammonia are one of the common malodorous compounds that can be found in emissions from many sewages treatment plants and industrial plants. Therefore, removing these harmful gases from emissions is of significance in both life and industry because they can cause health problems to human and detrimental effects on the catalysts. In this work, pyrolytic carbon blacks from waste tires were used to develop adsorbent with good adsorption capacity for removal of hydrogen and ammonia. Pellet-type adsorbents were prepared by a mixture of carbon black, metal oxide and sodium hydroxide or hydrochloric acid, and their adsorption capacities were estimated by using breakthrough curve of a continuous fixed bed adsorption column at ambient condition. The adsorbent manufactured with a mixture of carbon black, iron oxide(III) and sodium hydroxide showed the maximum working capacity of hydrogen sulfide. For ammonia, maximum working capacity was obtained by the adsorbent manufactured with a mixture of carbon black, copper oxide(II) and hydrochloric acid.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.3
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• pp.1259-1264
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• 2014

Hydrogen is in the world limelight for future energy source, and it has been already used in various industry fields including aerospace. The extremely fine molecule of the hydrogen can be easily leaked from tiny size of the crack on the surface of transporting pipes or storage tanks, and it could bring on awfully terrible disaster. In this study, Laser-Induced Breakdown Spectroscopy (LIBS) was employed to develope a reliable detection scheme for a small quantity of hydrogen leakage. Effect of three different metal substrates (i.e. Al, Cu, SUS) on plasma generation and the intensity of the hydrogen atomic signal was investigated, and the surface damage of the substrates due to repetitive laser shots was observed using Scanning electron microscope. It was also evaluated how the surface damage could distort the atomic signal. The intensity of the atomic signal was found to be the strongest, and the signal distortion due to the surface damage was approximately $100W/m^2$ lower when Al was used for the substrate.

• Journal of Ocean Engineering and Technology
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• v.27 no.5
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• pp.105-114
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• 2013

Lots of orders of special vessels and offshore plants for developing the resources in deepwater have been increased in recent. Because the most of accidents on those structures are caused by fire and explosion, many researchers have been investigated quantitatively to predict the cause and effect of fire and explosion based on both experiments and numerical simulations. The first step of the evaluation procedures leading to fire and explosion is to predict the dispersion of flammable or toxic material, in which the released material mixes with surrounding air and be diluted. In particular turbulent mixing, but density differences due to molecular weight or temperature as well as diffusion will contribute to the mixing. In the present paper, the numerical simulation of hydrogen dispersion inside a simple-shaped offshore structure was performed using a commercial CFD program, ANSYS-CFX. The simulated results for concentration of released hydrogen are compared to those of experiment and other simulation in Jordan et al.(2007). As a result, it is seen that the present simulation results are closer to the experiments than other simulation ones. Also it seems that the hydrogen dispersion is closely related to turbulent mixing and the selection of the turbulence model properly is significantly of importance to the reproduction of dispersion phenomena.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.45 no.3
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• pp.59-68
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• 2013

The cotton contains various impurities such as protein, wax, pectins, coloring matter, even though cotton has been a major source of pure cellulose. The purification processes have been commonly applied to obtain the pure cellulose. However the excessive purification treatments could lead to the damage in the cellulose structure which could result in the degradation of cellulose and the limited application of cotton cellulose. In this study, the changes in cellulose structural properties such as crystallinity and DP(degree of polymerization) by the various conditions of the purification processes were investigated. The less toxic agents such as hydrogen peroxide and sodium silicate were applied for the purification treatment in this study. The increase in the process times, the temperature and the applied amount of chemical agents resulted in the more purified cellulose. The DP of cotton cellulose was increased at the first weak conditions by the reduction of small molecules such as pectin, wax, and so on. Especially the 2 % addition amount of $H_2O_2$ with $Na_2SiO_3$ resulted in the higher value in the DP and the brightness compared to the 1.5 % addition amount of $H_2O_2$. However, the 4 % addition amount of $H_2O_2$ with $Na_2SiO_3$ showed the decreased value because of excessive treatment. In case of the changes in the crystallinity (Gjk), the highest value of the crystallinity was obtained by the 2% addition amount of $H_2O_2$ on the cotton cellulose, which showed similar with the change in the DP.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 1999.04a
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• pp.84-88
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• 1999

In chlorine dioxide delignigication or bleaching, chlorate is mainly formed by the reaction between chlorite and hypochlorous acid, thus scavengers of chlorine or hypochlorous acid can be used to reduce the formation of chlorate which is unfavorable to environment. In this study, additives such as sulfamic acid, DMSO, hydrogen peroxide, or sodium chlorite was added to chlorine solution or pure $ClO_2$ solution to check their reactivity with $Cl_2$ and $ClO_2$. These additives were also added directly into general $ClO_2$ solution which contained certain amount of chlorine, then the additive-treated $ClO_2$ solution were used in bleaching stages. The aim of this procedure was to remove the original amount of chlorine that was thought to be possibly the main reason for the formation of chlorate and AOX. The additives were found to be able to eliminate chlorine very fast and selectively, but $H_2$ $O_2$ should be used under pH4, otherwise it also reacts with $ClO_2$. After the additives reacted With $Cl_2$, DMSO turned into an inactive product $(CH_3)_2SO_2$, While Sulfamic acid turned into $HClSO_3H$ that still remained active in oxidation, and $NaClO_2$ produced $ClO_2$. The addition of $HNaClO_2$ showed significant improvement in delignification but the deeper delignification led to higher formation of chlorate. When the additive-treated chlorine dioxide solutions were used in bleaching, both sulfamic acid, DMSO, and hydrogen peroxide showed no significant changes of DE brightness and Kappa number. The formation of chlorate was reduced by addition of sulfamic acid, DMSO and hydrogen peroxide.