• Korean Journal of Pharmacognosy
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• v.19 no.4
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• pp.217-227
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• 1988

An alternative to the well known reversed-phase separations on chemically-boned phases has been developed. The approach is based on a dynamic modification of bare silica with long chain quaternary ammonium ions. The influence of the concentration and type of quaternary ammonium ion, the pH value and the ionic strength of the eluent on the selectivity towards test solutes has been investigated. The large number of parameters that can be attained. Once established, a high degree of reproducibility of the selectivity between solutes is obtained even when using different brands of silica; this is in contrast to the situation when using chemically-bonded phases, such as for example, different brands of octadecylsilyl-bonded silica materials. Examples of the use of system in pharmaceutical analysis and drug metabolism studies are given.

• YAKHAK HOEJI
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• v.18 no.3
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• pp.183-189
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• 1974

Distribution coefficients between nitrobanzene solution and deionized water, show a straight line when the number of alkyl radicals against the logarithm of distribution coefficient of the salts was plotted. After extracting salts of the indicator and the cationic surfactants with organic solvents, and employing the colorimetric method was used. A calculation method of distribution coefficients of the salts in the organic solvent has been suggested and it could be used for the extraction equilibrium of the primary amine, $CH_{3}(CH_2)_{n}NH_3^+$ secondary amine, $CH_{3}(CH_2)_{n}NH_{2}(CH_3)^+$, tertiary amine $CH_{3}(CH_2)_{n}NH(CH_3)_2^+$ and quaternary ammonium, $CH_{3}(CH_2)_{n}N(CH_3)_3^+$MO$^-$salts, (n=3,5,7,11).

• Journal of Radiation Industry
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• v.6 no.1
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• pp.49-54
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• 2012

Various anion exchange membranes were prepared by radiation graft copolymerization of vinylbenzyl chloride onto fluorinated films and subsequent quaternization with various tertiary amines such as trimethylamine, N,N-dimethylbuthylamine, N,N-dimethylaniline, and N-methylpiperidine. The quaternizations of the anion exchange membranes were confirmed by measuring of the ion exchange capacities of the membranes. The mechanical properties and the water uptakes were also measured. The elongation at break was found to be largely dependent on the fluorinated film, the quateranry ammonium, and the degree of grafting. The results indicate that the poly (ethylene-alt-tetrafluoroethylene) with quaternized trimethylamine moiety exhibits higher flexible property compared to the other prepared anion exchange membranes.

• The Korean Journal of Quaternary Research
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• v.18 no.2 s.23
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• pp.75-86
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• 2004

The sea level curve and environmental change were reconstructed at Sejuk-ri during the early Neolitic Age, based on the sedimentary facies, the distribution of remains and carbon datings. Before 6,500 years BP, the sea-level experienced one oscillation. The Neolitic men utilized geomorphic environment which formed according to the sea-level change. They might be occupied in gathering, fishing and hunting including whales hunting. The Neolitic men made acom hollows in order to remove tannin. Besides, they remained shell mounds which were formed from 6,500 years BP to around 6,000 years BP. They left the living place about 6,000 years BP because of transgression.

• The Korean Journal of Quaternary Research
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• v.19 no.1
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• pp.18-26
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• 2005

The East Asian summermonsoon is generally accompanied with the quasi-stationary front along the northern and northwestern periphery of the subtropical Northwest Pacific high. The rainy season in Korea has been called as Changma since the middle of 1500s. Understanding of Changma and heavy rainfall advancing along the Changma front is one of main interesting of Korean meteorologists. This study briefly summarized the descriptive characteristics of Changma and its relatedmechanism, definitions on the Changma period, and etymology of Changma through reviewing the previous studies on Changma.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 1998.10a
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• pp.235-240
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• 1998

Quaternary fault movement of the Ulsan fault system was interpreted by aenal photograph, field survey and trench excavation. The geomorphological evidences associated with active fault are clearly shown at Cheonbuk-myeon area, northern part of Ulsan fault system. In the trench wall one reverse fault(N 50$^{\circ}$E, 70$^{\circ}$E) is identified between basement rock (Miocene mudstone) and gravel deposits Another thrust fault (NS) extends up to the red and light brown soil layers. Middle terrace surface shows cumulative vertical displacements of about 3 to 7 m. The horizontai displacement of the red soil by faulting event is about 1.8 to 2.4m. The age of the fault activity is younger than that of the soil layer, which is roughly estimated to be late Quaternary (about 100Ka)

• Economic and Environmental Geology
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• v.27 no.2
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• pp.209-212
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• 1994

Cheju Island was formed by volcanic activity probably related to the inferred geodynamics in the early Quaternary times. Paleostress analysis, in spite of a few fault slip data collected near Sanbangsan trachyte dome (dated 0.87 Ma) represents an extentional tectonic event with the direction ENE-WSW. Joint anayses in the vicinity of Seahwa reveal three extensional tectonic events of directions NW-SE, NE-SW and ENE-WSW. Especially the extensional event with the direction ENE-WSW affected the whole Cheju area during the most recent time.

• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.9-12
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• 2007

The transport mechanisms of the MTES (methyltriethoxysilane) templating silica/a-alumina composite membrane were evaluated by using four binary and one quaternary hydrogen mixtures through permeation experiments at unsteady- and steady-states. Since the permeation flux in the MTES membrane, through the experimental and theoretical studies, was affected by molecular sieving effects as well as surface diffusion properties, the kinetic and equilibrium separation should be considered simultaneously according to molecular properties. In order to depict the transient multi-component permeation on the templating silica membrane, the GMS (generalized Maxwell-Stefan) and DGM (dust gas model) were adapted to unsteady-state material balance.

• The Korean Journal of Quaternary Research
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• v.1 no.1
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• pp.47-67
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• 1987

Geologically speaking, many lava tunnels and caves are characteristic geomorphic features in Che-Ju Island. Especially, cave-ins are found along cliffs of shoreline and streams. The prehistoric early inhabitants in the island used the tunnels and cave-ins as their major shelters from palaeolithic period to the iron period (AD300-600). These tunnel-dwelling sites and rock-shelters are unsidered to be long-term shelters from the palaeolithic period to the neolithic period. However, these shelters and sites might be changed as temporary camping sites from the bronze to the iron period.

• The Korean Journal of Quaternary Research
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• v.22 no.1
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• pp.23-27
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• 2008

Paleoenvironmental evolution in South Korea is investigated on the basis of fluctuations in biogenic silica content in sediments from Cheollipo coast on western shore. The biogenic silica measurement was done by alkaline extraction technique. The concentration of the biogenic silica in the Cheollipo coastal sediments is generally low, with an average of 1.2 %. The proxy of biogenic silica records in Cheollipo sediments implies the significant difference of bio-productivity on Korean Peninsula in comparison with those in lacustrine sediments in interior terrestrial continent of the Eurasia.