• Corrosion Science and Technology
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• v.8 no.4
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• pp.139-142
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• 2009

Recently, quaternary titanium alloys of the system Ti-Nb-Ta-Zr received considerable research interest as potential implant materials because of their excellent mechanical properties and biocompatibility. However, only few reported works were available on the corrosion behavior of such alloys. Hence, in the present work, electrochemical corrosion of Ti-35Nb-5Ta-7Zr alloy, which has been fabricated by arc melting and heat treatment, was studied in 0.9 wt% NaCl at $37\pm1^{\circ}C$, along with biomedical grade Ti-6Al-4V and CP-Ti. The phase and microstructure of the alloys were investigated employing XRD and SEM. The results of electrochemical studies indicated that the corrosion resistance of the quaternary alloy was inferior to that of Ti-6Al-4V and CP Ti.

• The Korean Journal of Quaternary Research
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• v.6 no.1
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• pp.21-32
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• 1992

The paleoclimate of the Chungbu Mountainous Region, Mts. Seorak and Sobaek, was estimated by means of dendroclimatic methodology, The annual growth value of tree-rings is deeply interrelated with the mean temperature of April-May and July-August. The mean temperature of April-May of the reconstruction period(1635-1911), observation period(1912-1989), and the whole period(1635-1989) is 13.58$^{\circ}C$, 13.69$^{\circ}C$, and 13.6$0^{\circ}C$, respectively. That of July-August is $24.50^{\circ}C$, $24.62^{\circ}C$, and $24.58^{\circ}C$ respectively. The reconstructed mean temperature data for April-May and for July-August reveal 13.2 and 12.9 year cycles.

• Textile Coloration and Finishing
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• v.4 no.3
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• pp.131-135
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• 1992

Quaternary aminized cellulosic adsorbents (C $A_{QA}$ ) which exhibit adsorption capacities for anionic dyestuffs for the treatment of colored waste water and re-use of the treated water were studied. The isotherms and thermodynamic parameters of C.I. Acid Orange 7, solution considered as a model of negatively charged coloring matters for C $A_{QA}$ , were determined. Batch method and flow method were employed to determine decoloring capacity of cellulosic adsorbents for Orange 7. The cellulosic adsorbents exhibited much better adsorption capacity than activated carbon. Furthermore the exhausted cellulosic adsorbents could be readily regenerated by washing with dilute sodium hydroxide.

• The Korean Journal of Quaternary Research
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• v.17 no.2
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• pp.39-41
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• 2003

Pollen and spores as well as their morphological characteristics are biological stability materials in which contains historical information about vegetation and climate changes. As noted researcher Neishtadt in 1971, the lake and swamp deposits were developed only in Holocene period. The geological history of Darkhad depression which is situated in the Northern end of Mongolia from ancient time become under scientific interest of many researchers. Our investigation was focused on pollen analysis of lake sediment of Darkhad depression which caused bottom of paleolake. In Mongolia the palynology science is beginning to develop since 1990 and in 2000 the laboratory of palynology was established at the department of Biology, State Pedagogical University of Mongolia. Researchers from this laboratory working on pollen morphology of present flora in order to classify plants taxonomy. Another part of our investigation is mellitopalynology, which is studying of pollen grains in a honey. Although, this research has been extending by pollen analysis of sediment and lake deposits in past few years on the basis of high sensitive microscope and modem technology.

• The Korean Journal of Quaternary Research
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• v.17 no.2
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• pp.63-69
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• 2003

Three tree-ring monsoon rainfall reconstructions from China and Korea have been used in this paper to investigate the variation of the East Asian summer monsoon over the past 160 years. Statistically, there is no linear correlation on a year-by-year basis between Chinese and Korean monsoon rainfall, but region-wide synchronous variation on decadal-scale was observed. Strong monsoon intervals (more rainfall) were 1860-1890, 1910-1925,1940-1960, and weak monsoon periods (dry or even drought) were 1890-1910, 1925-1940, 1960- present. Reconstructions also display that the East Asian summer monsoon suddenly changed from strong into weak around mid-1920, and the East Asian summer monsoon keeps going weak after 1960.

• Bulletin of the Korean Chemical Society
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• v.24 no.9
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• pp.1269-1275
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• 2003

The quaternary carbon-containing alcohols (1-6) were resolved enantioselectively by various lipases such as PFL (Pseudomonas fluorescens lipase), LAK (Pseudomonas fluorescens lipase), CRL (Candida rugosa lipase) and PCL (Pseudomonas cepacia lipase). The enzymatic resolution of racemic alcohol $({\pm})-2$ gave the excellent enantioselectivity in favor of (S)-2d in 99% ee, while those of the racemic alcohols (1, 3, 4, 5 and 6) gave the resolved alcohols with moderate to good enantioselectivity. Also, their absolute configurations were determined by chemical transformation to the known compounds.

• Journal of the Korean Chemical Society
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• v.15 no.1
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• pp.1-3
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• 1971

The methanol extract of the fruits of Forsythia Koreana NAKAI was separated and purified. The quaternary base chloride was obtained. Through the mass spectrogram, ultraviolet spectra, infrared spectra, elemental analysis and qualitative tests it was identified as betaine hydrochloride.

• Macromolecular Research
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• v.17 no.3
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• pp.144-148
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• 2009

Poly(1-oxo-2-phenyltrimethylene) was synthesized by palladium-catalyzed copolymerization of styrene and carbon monoxide in quaternary ammonium ionic liquids. The $[Pd(bipy)_2][PF_6]_2$ compound had relatively more catalytic activity than $[Pd(bipy)_2][BF_4]_2$ in ionic liquids. The catalytic activity of palladium (II) composite catalyst was superior to the catalyst formed in situ from palladium acetate, 2,2-bipyridyl, and $X^-$ ($X^-=PF_6^-$, $BF_4^-$) in ionic liquids. The effects of the volume of ionic liquids, reaction time and benzoquinone content on the copolymerization were also described.

• Proceedings of the Korean Geotechical Society Conference
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• 2003.03a
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• pp.747-752
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• 2003

This study was carried out to understand the stratigraphy and depositional environment of clayey soils that distributed in the Gadeok-do area, Kimhae plain (Nakdong estuary). For the study, SPT core sampling and magnetic susceptibility analysis were conducted. Soils in study area is classified into five sedimentary facies ascending order; sand/gravel. clay, sand/gravel, clay, interbedded sand and silty clay. Analysis of magnetic susceptibility for Gadeok-do clayey soil reveals that depositional process and environment can be divided into upper, middle and lower layer, and they are closely related to the sea level change since late Quaternary.

• The Korean Journal of Quaternary Research
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• v.18 no.2 s.23
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• pp.17-17
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• 2004

The Pleistocene lake level and climate development is described by proxies from sediment, pollen and diatom records in Mongolia and Northwest-China. It could be proved that higher lake levels seem to have existed during the old and mid Pleistocene period interpreted on the base of geomorphological and sedimentological reords. They are dated in a relativ time scale. The lake basins are filled up to 300 m by limnic deposits, which foused on a constant water balance of more than 700.000 years. Late Glacial and Holocene lake level fluctuations and climate changes can be proved by biostratigraphic records pointing to dry and wet phases. Only for the youngest history desiccation of some lakes are related to human impact.