• Nuclear Engineering and Technology
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• v.51 no.7
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• pp.1799-1804
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• 2019

The concept of a new method, the CARBEX (CARBonate EXtraction) process, was proposed for reprocessing of spent uranium oxide fuel. The proposed process is based on use of water solutions of $Na_2CO_3$ or $(NH_4)_2CO_3$ and solvent extraction (SE) by the quaternary ammonium compounds for selective recovery and purification of U from the fission products (FPs). Applying of SE allows to reach high degree of purification of U from FPs. Carrying out the processes in poorly aggressive alkaline carbonate media leads to increasing safety of SNF's reprocessing and better selectivity of separation of lanthanides and actinides. Moreover carbonate reprocessing media allows to carry out a recycling and regeneration of reagents. We have been done laboratory scale experiments on the extraction components of simulated voloxidated spent fuel in the solutions of NaOH or $Na_2CO_3-H_2O_2$ and recovery of U from carbonate solutions by SE method using carbonate of methyltrioctylammonium in toluene. It was shown that the purification factors of U from impurities of simulated FPs reached values $10^3-10^5$. The received results support our opinion that CARBEX after the further development can become more safe, simple and profitable method of spent fuel reprocessing.

• The Korean Journal of Quaternary Research
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• v.16 no.2
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• pp.1-8
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• 2002

In this paper, the writer attempts to clarify causes by general man and weather factor on forest fire occurrence in Kosong-Area, 1995-2001. The major results are summarized as follows: The forest fire at Kojin-ri, Sonyusil-ri and Majwa-ri occurred at the same area over 3 times and that Hakya-ri, Songdae-ri and Inhung-ri, at the adjoining land over 3times. In the total 46 times of forest fire, fire frequence was greatest in March(11 time) and April(11 time) followed by November(7 time), January(6 time), February(6 time). December(3 time), October(2 time). Hours on frequent forest fire are from 11:00 till 18:00. Number for forest fire occurrence by causes was greatest in military training followed by burning paddy fields, debris burning, burning agricultural debris, visiting a grave, cigarette and arson. Frequent forest fire in Kosong-Area coincide not only with above normal temperatures, but also with below normal relative humidity. When the strong winds appear at Kosong-Area, the properties of daily surface chart re the south high and north low pressure pattern in the Far East Asia.

• Geophysics and Geophysical Exploration
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• v.8 no.1
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• pp.34-40
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• 2005

We have used the microtremor method, with arrays of up to 96 m diameter, to carry out non-invasive estimation of shear-wave velocity profiles to a depth of 30 to 50 m in unconsolidated Quaternary Yarra Delta sediments. Two silt units (Coode Island Silt, and Fishermans Bend Silt) dominate our interpretation; the method yields shear velocities for these units with precision of $5\%$, and differentiates between the former, softer unit ($V_s$=130 m/sec) and the latter, firmer unit ($V_s$=235 m/sec). Below these silts, the method resolves a firm unit correlating with known gravels ($V_s$ 500 to 650 m/sec). Using surface traverses with the single-station H/V spectral ratio method, we show that the variation in thickness of the softer silt can be mapped rapidly but only qualitatively. The complexity of the geological section requires that array methods be used when quantitative shear-wave velocity profiles are desired.

• Geophysics and Geophysical Exploration
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• v.8 no.4
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• pp.243-250
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• 2005

Analysis of high-resolution seismic profiles acquired from the inner shelf off the southern coast of Korea reveals that the inner shelf sequence can be divided into three stratigraphic units formed after the Last Glacial Maximum (LGM). Unit I is characterized by complex seismic facies including semi-transparent, stratified, and hummocky reflections on seismic records. It consists of sandy mud or muddy sand, deposited under estuarine environment during the post-glacial transgression. Unit II acoustically shows semi-transparent or hummocky reflections and consists of sand with gravels and shell debris, produced by shoreface erosion during the transgression. Unit III is characterized by transparent or semi-transparent seismic facies and consists of mud originated from the Nakdong and Seomjin rivers during recent highstand of sea level. Unit III is confined to the inner shelf with an extenal form of stratal wedge.

• Journal of the Korean Applied Science and Technology
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• v.34 no.1
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• pp.142-151
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• 2017

Cationic surfactants have a bactericidal effect and the study for effective development of them became important parts in the industry. There have been increasing researches that focus on the development of products having not only outstanding features but also safety and biodegradability. In this work, novel ester-type cationic surfactants were obtained via Michael addition reaction. Intermediates were quantitatively prepared by the Michael addition reaction between alkyl acrylate and amine compounds under mild conditions without solvent and catalyst. The intermediates were quaternized with dimethyl sulfate. HQ21 with two hydrophobic groups and a hydrophilic group and HQ22 with two hydrophobic groups and two hydrophilic groups were obtained. The structures of the products were characterized by 1H-NMR, HR-MS and FT-IR and biodegradability of the products were tested.

• The Korean Journal of Quaternary Research
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• v.13 no.1
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• pp.1-23
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• 1999

A palynological investigation of the Annyeong-ri, Hwasung-gun Gyeonggi-do, in where Yung-Nung and Gun-Nung are located, was carried out for the first time. From the pollen analysis, two pollen zones are established: Pollen Zone I : Ainus-Quercus-Pinus and Pollen Zone Ⅱ : Pinus. Pollen Zone I is characterized by Mixed coniferous and deciduous broadleaved vegetation during about 3,500 yr. B.P.-2,000 yr. B.P., while after 2,000 yr. B.P. Pollen Zone Ⅱ appears to be Coniferous vegetation and Evergreen broadleaved vegetation. The former reflects there was a lowland fluvio-lacustrine environment before fully lacustrine one which represents the latter. Pollen analysis indicates the vegetation before 2,000 yr. B.P. was controled by environmental factor such as climate conditions, whereas after that time vegetation was strongly effected by human's impact. It is concluded that pollen analysis is useful to find out the relationship between vegetation history and man's interference. In addition freshwater algae play to tell the lake environments.

• The Korean Journal of Quaternary Research
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• v.17 no.2
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• pp.123-128
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• 2003

This study was conducted to examine the water use efficiency (WUE) in five species of one-year-old seedlings grown in a field nursery in Mongolia. Larix sibirica and Pinus sylvestris are the most dominant coniferous species while Ulmus pumila is an important deciduous species known well-adapted in harsh conditions such as in semi-arid forests and Gobi desert regions. Caragana arborescens (Siberian pea shrub) and Hippophae rhamnoides are N-fixing shrubs in Mongolia. Thirty one-year-old seedlings were sampled from each of the five species (a total of 150 samples) and measured for net photosynthetic rate (Pn) and transpiration rate (E). The Pn and E were used to calculate and compare the WUE of each species. Pn differed significantly among the five species (p < 0.05). However, there was no significant difference in Pn between L. sibirica and H. rhamnoides (p > 0.05). C. arborescens showed the highest Pn whereas U. pumila did the poorest. E differed significantly among the five species (p < 0.05). L. sibirica and U. pumila showed considerably lower E than other species. Thus, WUE values of coniferous species such as L. sibirica and P. sylvestris were significantly greater than deciduous or shrub species such as U. pumila, C. arborescens and H. rhamnoides (p < 0.01). It may result that conifers showed relatively high water use efficiency than deciduous or shrub trees due to their lower transpiration rates, which resulted in morphological and physiological characteristics of their leaves. This may indicate that L. sibirica and P. sylvestris can be widely used for rehabilitation works in Mongolia attributed to their dominant distributions but also their high drought-resistance properties.

• The Korean Journal of Quaternary Research
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• v.17 no.2
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• pp.79-84
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• 2003

This study revealed the differences in runoff processes of granite drainage basins in Korea and Mongolia by hydrological measurements in the field. The experimental drainage basins are chosen in Korea (K-basin) and Mongolia (M-basin). Occurrence of intermittent flow in K-basin possibly implies that very quick discharge dominates. The very high runoff coefficient implies that most of effective rainfall quickly discharge by throughflow or pipeflow. The Hortonian overlandflow is thought to almost not occur because of high infiltration capacity originated by coarse grain sized soils of K- basin. Very little baseflow and high runoff coefficient also suggest that rainfall almost does not infiltrate into bedrocks in K-basin. Flood runoff coefficient in M-basin shows less than 1 %. This means that most of rainfall infiltrates or evaporates in M-basin. Runoff characteristics of constant and gradually increasing discharge imply that most of rainfall infiltrates into joint planes of bedrock and flow out from spring very slowly. The hydrograph peaks are sharp and their recession limbs steep. Very short time flood with less than 1-hour lag time in M-basin means that overland flow occurs only associating with rainfall intensity of more than 10 mm/hr. When peak lag time shows less than 1 hour for the size of drainage area of 1 to 10 km2, Hortonian overland flow causes peak discharge (Jones, 1997). The results of electric conductivity suggest that residence time in soils or weathered mantles of M-basin is longer than that of K-basin. Qucik discharge caused by throughflow and pipeflow occurs dominantly in K-basin, whereas baseflow more dominantly occur than quick discharge in M-basin. Quick discharge caused by Hortonian overlandflow only associating with rainfall intensity of more than 10 mm/hr in M-basin.

• Analytical Science and Technology
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• v.7 no.3
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• pp.387-393
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• 1994

Quantitative analytical conditions for chromium using solvent extraction followed by atomic absorption spectrometry was studied. Trioctylamine(TOA) in tertiary amine or Trioctylmethylammoniumchloride(TOMAC) in quaternary ammonium salt, both containing octyl group was used as an anion exchangers. Absorbance were measured for the different kinds of acid added and as changing the concentration of acid by graphite furnace atomic absorption spectrometer. The maximum absorbance was obtained at the concentrations of HCl, 0.1M to 0.3M for TOA and 0.03M to 0.1M for TOMAC. Mole ratios over 1:1 of TOA or TOMAC dissolved in MIBK solution to chromium in sample shows optimum extraction efficiency while HCl was added to the MIBK. As a result of scrutinizing the extraction process, the methods employed in this experiment turned out to be better extraction efficiency for chromium, compared to similar extraction methods.

• The Korean Journal of Quaternary Research
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• v.15 no.2
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• pp.75-81
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• 2001

We have analyzed the pollen sequence since the Late Glacial at Sorori Archaeological Site. The Sorori Site is an open site located at Soro-ri, Oksan-myeon, Cheongwon-gun, Chungchongbukdo. The main results are as follows: Four forest zones have been distinguished. \circled1 OS-1 zone : Pinus-Abies-Picea forest (the sub-alpine conifer forest), the Late Glacial (about 15,000~10,000yr. B.P.) ; \circled2 OS-2 zone : Pinus-Colyus forest (the mixed conifer and deciduous broad-leaved forest), R I (about 10,000 yr.B.P.) : \circled3 OS-3 zone : Alnus-Quercus forest (the cool temperate deciduous broadleaved forest), R II(about 10,000~2,000yr.B.P.) : \circled4 OS-4 zone : Pinus forest (the conifer forest), R III (about after 2,000yr.B.P.)