• Proceedings of the Korean Quaternary Association Conference
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• 2005.06a
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• pp.7-11
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• 2005

The soil erosion processes have estimated using spatial distribution of 137Cs radionuclide in Granite and Sedimentary Hillslopes in South Korea. The local variability of 137Cs inventory indicates that was related positively to organic matter content, clay content and water content and negatively to hydraulic permeability and slope gradient for bulk samples in different landforms within Granite and Sedimentary rock basins. The vertical variability of 137Cs inventory shows that most of 137Cs concentration and organic matter were accumulated between 0 and 2cms and gradually decrease with soil depth in incremental samples in both basins. The vertical variability of 137Cs inventories shows that 137Csinventories increase as we go to toward downslope in both basins. Finally, the soil loss values indicate that hillslope erosion processes are more intensive in Granite rock basin than those in Sedimentary rock basin.

• Journal of Photoscience
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• v.12 no.3
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• pp.163-169
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• 2005

Recent reports suggest that floral organs such as sepals, petals, stamens, and carpels are specified by quaternary MADS protein complexes with different combinations. The formation of quaternary complexes of ABCDE MADS proteins may be the molecular basis of ABCDE model for the floral organ development. The MADS complexes involved in each floral organ development seem to be conserved in at least dicot species although detailed molecular mechanism is slightly different depending on species. Even in monocot, at least rice, MADS complexes similar to those in dicot exist, suggesting that the floral organ specification by MADS protein complexes may be conserved in most of plants. The MADS protein complexes may have more specific recognition of target genes or more transcription activation ability than monomers or dimers, resulting in finely regulated floral organ development.

• The Korean Journal of Quaternary Research
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• v.3 no.1
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• pp.47-54
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• 1989

Pyrite ($FeS_2$) content in brackish and salt marsh sediments is relatively higher than the amount in freshwater marsh sediments. Different values of pyrite sulfur ($FeS_2$-S) content in sediments from the Hiroshima Delta indicate that poorly drained salt marsh had developed between 27.0m and 28.0m below mean sea-level and palaeo-sea-level was constant for several hundreds of years in the same depth during the early Holocene Epoch.

• Journal of the Korean Chemical Society
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• v.19 no.5
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• pp.351-354
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• 1975

Some quaternary ammonium salts were synthesized from 2-phenylethyl tosylate with pyridine and N,N-dimethyl p-toluidine, which were identified by NMR and IR spectrometry and the comparison of their physico-chemical constant has been made. It is found that the yield of the salts synthesized were significantly improved in acetonitrile rather than in acetone.

• Analytical Science and Technology
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• v.28 no.2
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• pp.112-116
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• 2015

Extraction of quaternary ammonium compounds (choline and betaine) from plant samples (spinach) using ion exchange resin (AG1, OH⁻ form) is a very simple and inexpensive approach. However, it is very hard to determine amounts of choline and betaine simultaneously using high-performance liquid chromatography-ultraviolet (HPLC-UV) detection. Unlike choline, betaine has low molar absorptivity in UV-visible (UV-Vis) region, which makes it difficult to carry out UV-Vis detection of betaine. The mixture of quaternary ammonium compounds (choline and betaine) was derivatized using 2-bromo acetophenone as a derivatizing agent. As a result, choline did not react with the derivatizing agent, whereas betaine formed a betaine derivative. This betaine derivative exhibited detectable UV absorption with baseline separation between choline and the betaine derivative. Thus, with this method, choline and betaine can be determined simultaneously by using the HPLCUV method through one-step derivatization, which is an easy, sensitive, and reliable method.

• Archives of Pharmacal Research
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• v.24 no.2
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• pp.89-94
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• 2001

Several quaternary pyridinium cephalosporin analogues were prepared analogues were Prepared and evaluated in vitro for antibacterial activity against selected Gram-positive and Cram-negative organisms. Most of the synthesized analogues were either as effective or less effective against the tested bacterial organ isms than the reference com pounds, Cefpirome and Ceftazidime.

• Bulletin of the Korean Chemical Society
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• v.31 no.4
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• pp.829-834
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• 2010

Ligand variation was carried out on a cobalt(III) complex of Salen-type ligand comprised of 1,2-cyclohexenediamine and salicylaldehyde bearing a methyl substituent on 3-position and -[$CMe(CH_2CH_2CH_2N^+Bu_3)_2$] on 5-position, which is a highly active catalyst for $CO_2$/propylene oxide copolymerization. Replacement of the methyl substituent with bulky isopropyl group resulted in alteration of the binding mode, consequently lowering turnover frequency significantly. Replacement with an ethyl group preserved binding mode and activity. Replacement of the tributylammonium unit with trihexylammonium or trioctylammonium, or replacement of 1,2-cyclohexenediamino unit with -$NC(Me)_2CH_2N$- decreased activity, even though the binding mode was unaltered.

• Applied Chemistry for Engineering
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• v.9 no.4
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• pp.603-607
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• 1998

Cellulose was reacted with ethylene oxide to get hydroxyethylcellulose. Quaternary ammonium salt was produced by reaction of epichlorohydrin and trialkylamine. The epoxide ring was opened by acid addition to 3-chloro-2-hydroxypropyltrialkylammonium chloride. Previously unreported two compounds, hydroxyethylcellulose-2-hydroxypropylammonium chloride ether and hydroxyethylcellulose-2-hydroxypropyltriethylammonium chloride ether were synthesized by substitution reaction of hydroxyethylcellulose with glycidyltrialkylammonium chloride or 3-chloro-2-hydroxypropyl-glycidyltrialkylammonium trialkylammonium chloride. All of the compounds including starting materials and reaction intermediates were characterized by $^1H$-NMR and FT-IR spectroscopy.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.2C
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• pp.153-157
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• 2009

In this paper, for even integer N, we propose a new construction method of quaternary low correlation zone(LCZ) sequence set from a binary LCZ sequence set with parameters (N,M,L,$\varepsilon$). Proposed method applies the inverse gray mapping from Krone and Sarwate to binary LCZ sequences and their phase shifts. The only needed condition of binary LCZ sequence set used in this construction is even period.

• Advances in concrete construction
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• v.11 no.3
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• pp.207-217
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• 2021

This study relates to a production of Quaternary Cement Concrete (QCC) prepared by using Micro Silica (MS), Marble Dust (MD) and Rice Husk Ash (RHA), followed by an investigation towards fresh and hardened properties of blended concrete. A total of 39 mixes were cast by incorporating different percentages of MS (6%, 7% and 8%), MD (5%, 10% and 15%) and RHA (5%, 10%, 15% and 20%) as partial replacement of Ordinary Portland Cement. The workability of fresh concrete was maintained in the range of 100±25 mm by adding 0.7% of Super Plasticizer in the mix. Optimum mechanical strength was observed at combination of 8% MS+5% MD+10% RHA. Marble dust replacement from 10 to 15% and Rice husk ash replacements from 15 to 20% depicted a substantial reduction in compressive strength at all ages. Durability parameter with respect to water absorption at 28 days shows an increasing trend as the percentage of blending increases.