• Transactions of the Korean hydrogen and new energy society
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• v.24 no.1
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• pp.44-49
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• 2013

Hydrogen penetration into a metal leads to damages and mechanical degradations and its content measurement is of importance. For a precise measurement, a sample preparation procedure must be optimized through a series of studies on sample washing and drying. In this study, two-step washing with organic solvents and thermal soaking in inert gas were tried with a rod-shaped, API X65 steel sample. The samples were machined from a steel plate and then washed in acetone and etyl-alcohol for 5 minute each and dried with compressed air. After then, the samples were thermally soaked in a home-made nitrogen gas chamber during 10 minute at different heat gun temperatures from 100 to $400^{\circ}C$ and corresponding temperature range in the soaking chamber was from 77 to $266^{\circ}C$ according to the temperature calibration. Hydrogen residue in the samples was measured with a hot extraction system after each soaking step; hydrogen residue of $0.70{\pm}0.12$ wppm after the thermal soaking at $77^{\circ}C$ decayed with increase of the soaking temperature. By adopting the heat transfer model, decay behavior of the hydrogen residue was fitted into an exponential decay function of the soaking temperature. Saturated value or lower bound of the hydrogen residue was 0.36 wppm and chamber temperature required to lower the hydrogen residue about 95% of the lower bound was $360^{\circ}C$. Furthermore, a thermal desorption spectroscopy was done for the fully soaked samples at $360^{\circ}C$. Weak hydrogen peak was observed for whole temperature range and it means that hydrogen-related contaminants of the sample surface are steadily removed by heating. In addition, a broad peak found around $400^{\circ}C$ means that parts of the hydrogen residue are irreversibly trapped in the steel microstructure.

• Journal of Applied Biological Chemistry
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• v.54 no.3
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• pp.214-217
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• 2011

Fumigant, methyl bromide which is used in most countries for plant quarantine, has been designated and under control as ozone depleting substance. For developing alternative chemicals for methyl bromide, many countries have been intensifying their capacity. This study was carried out to investigate the residue patterns of hydrogen cyanide which is commonly used for plant quarantine. Hydrogen cyanide was treated onto the orange, banana, and pineapple at recommended and double doses and then sampling was done at 1 and 3 day after fumigation treatment. Residue of hydrogen cyanide was found safe because average residue levels on orange, banana, and pineapple after 3 days of fumigation treatment were $0.57{\pm}0.05$, $0.21{\pm}0.17$, and $0.41{\pm}0.08$ ppm, which were lower than the MRLs of Korea (5 ppm), Japan (5 ppm), USA (50 ppm), and Canada (25 ppm). Hydrogen cyanide are expected to be used as alternative chemicals for methyl bromide fumigant for orange, banana, and pineapple.

• Journal of the Korean institute of surface engineering
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• v.31 no.2
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• pp.117-126
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• 1998

In this study, the residue remaining on the silicon wafer during the oxide overetching using $C_4F_8/H_2$ helicon were plasmas and effects of various cleaning and annealing methods on the removal of the remaining residue were investigated. The addition of 30%$H_2$ to the C4F8 plasma increased the C/F ratio and the thickness of the residue on the etched silicon surface. Most of the residuse on the etched surfaces colud be removed by the oxygen plasmsa cleaning followed by thermal annealing over $450^{\circ}C$. Hydrogen-coataining residue formed on the silicon by 70%$C_4F_8/30%H_2$ helicon plasmas was more easily removed than hydrogen-free residue formed residue formed by $C_4F_8$ helicon wear plasmas. However, damage remaining on the silicon surface overetched using 70%$C_4F_8/30%H_2$ helicon plasmas was intensive and the degree of reocvery duing the post-annealing was lower.

• Bulletin of the Korean Chemical Society
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• v.18 no.1
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• pp.18-23
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• 1997

Data from structure/activity studies in vir gene induction system have led to evaluate the working hypothesis of interaction between phenolic inducers and phenol binding proteins. The primary specificity in the association of a phenolic inducer with its receptor in our system is hypothesized to be the hydrogen bonding interactions through the ortho methoxy substituents as well as the proton transfer between the inducer and the binding protein. In this paper the proposed working model for phenol-mediating signal transduction was evaluated in several ways. The importance of the general acid-base catalysis was first addressed by the presence of an acidic residue and a basic residue in the phenol binding protein. Series of compounds were tested for vir gene expression activity to confirm the generation of a strong nucleophile by an acidic residue and an involvement of a basic residue as a proton acceptor. An attempt was made to correlate the pKa values of the phenolic compounds with vir gene induction activities as inducers to further support the proposed proton transfer mechanism. Finally, it was also observed that the regioselectively attached methoxy group on phenol compounds is required as the proper hydrogen bond acceptor.

• Carbon letters
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• v.24
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• pp.28-35
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• 2017

We demonstrated an effective way of preparing melt spinnable mesophase pitches via catalytic hydrogenation of petroleum residue (fluidized catalytic cracking-decant oil) and their subsequent thermal soaking. The mesophase pitches thus obtained were analyzed in terms of their viscosity, elemental composition, solubility, molecular weight, softening point and optical texture. We found that zeolite-induced catalytic hydrogenation under high hydrogen pressure contributed to a large variation in the properties of the pitches. As the hydrogen pressure increased, the C/H ratio decreased, and the solubility in n-hexane increased. The mesophase pitch with entirely anisotropic domains of flow texture exhibited good meltspinnability. The mesophase carbon fibers obtained from the catalytically hydrogenated petroleum residue showed moderate mechanical properties.

• BMB Reports
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• v.33 no.3
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• pp.268-275
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• 2000

In contrast to the pyrimidine (6-4)pyrimidone photoproduct [(6-4) adduct], its Dewar valence isomer (Dewar product) is low mutagenic and produces a broad range of mutations with a 42 % replicating error frequency. In order to determine the origin of the mutagenic property of the Dewar product, we used experimental NMR restraints and molecular dynamics to determine the solution structure of a Dewar·lesion DNA decamer duplex, which contains a mismatched base pair between the 3'-T residue and an opposed G residue. The 3'-T of the Dewar lesion forms stable hydrogen bonds with the opposite G residue. The helical bending and unwinding angles of the DW/GA duplex, however, are much higher than those of the DW/AA duplex. The stable hydrogen bonding of the G 15 residue does not increase the thermal stability of the overall helix. It also does not restore the distorted backbone conformation of the DNA helix that is caused by the forming of a Dewar lesion. These structural features implicate that no thermal stability, or conformational benefits of G over A opposite the 3'-T of the Dewar lesion, facilitate the preferential incorporation of an A. This is in accordance with the A rule during translesion replication and leads to the low frequent $3'-T{\rightarrow}C$ mutation at this site.

• 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.

• Transactions of the Korean hydrogen and new energy society
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• v.16 no.3
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• pp.209-218
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• 2005

To find a suitable metal component in oxygen carrier particles for chemical-looping hydrogen generation system(CLH), oxygen transfer capacities of metal components were compared and Ni has been selected as the best metal component. The proper operating conditions to achieve high hydrogen generation rate have been investigated based on the chemical-equilibrium composition analysis for water splitting reactor. Moreover, suitable compositions of syngas from gasifier of heavy residue to achieve high energy efficiency have been investigated by calculation of heat of reaction. Based on the selected operating conditions, the best configuration of two interconnected fluidized beds system for the chemical-looping hydrogen generator has been investigated as well.

• Transactions of the Korean hydrogen and new energy society
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• v.27 no.5
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• pp.612-619
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• 2016

Pitch synthesis reaction was studied based on the effect for chemical composition of feedstock. Feedstock was selected as pyrolyzed fuel oil (PFO) and coal-tar (CT), which are by-products in petroleum and steel industry. Pitch was prepared at $420^{\circ}C$ for 180 minutes on atmospheric pressure by thermal treatment. Thermal stability and softening point (SP) of the prepared pitches were investigated and their molecular weight distribution was analyzed by MALDI-TOF. PFO has various aliphatic compounds and coal-tar has high aromaticity with 3 wt% of primary quinoline insolubles. The thermal property of PFO was enhanced with polymerization reaction during the thermal treatment with increased molecular weight range. But CT was inferior to PFO because of side reaction by hetero elements. CTP was appeared molecular weight by 0~200 m/z.

• The Korean Journal of Food And Nutrition
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• v.9 no.2
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• pp.217-222
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• 1996

We studied about analyzing carbamate pesticides, organochlorine, organophosphorus pesticides simultaneously using by GC/MSD. For this, instead of HPLC which is generally used in analyzing carbamate pesticides, GC was used and all hydrogen of -NH group in carbamate pesticides were substituted for trifluoroacetyl group which is stable at heat And eight pesticide resdidues were not detected in nine samples circulated in the city.