• Korean Journal of Agricultural Science
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• v.7 no.1
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• pp.44-51
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• 1980

The population of indole-forming thermophile was obtained for the first time several samples of soil and compost manure. The population was highly enriched by successive transfer in the tryptophan liquid medium treated with antibiotics and dilution subculture cloning. Both indole-forming thermophile might be a Gram-negative bacterium hitherto unknown, but its pure culture has not yet been established due to the inability to grow on the solid media.

• Journal of Microbiology
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• v.42 no.2
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• pp.87-93
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• 2004

Twelve mecoprop-degrading bacteria were isolated from soil samples, and their genetic and phenotypic characteristics were investigated. Analysis of 16S rDNA sequences indicated that the isolates were related to members of the genus Sphingomonas. Ten different chromosomal DNA patterns were obtained by polymerase-chain-reaction (PCR) amplification of repetitive extragenic palindromic (REP) sequences from the 12 isolates. The isolates were found to be able to utilize the chiral herbicide meco-prop as a sole source of carbon and energy. While seven of the isolates were able to degrade both (R)-and (S)-mecoprop, four isolates exhibited enantioselective degradation of the (S)-type and one isolate could degrade only the (R)-enantiomer. All of the isolates were observed to possess plasmid DNAs. When certain plasmids were removed from isolates MPll, MP15, and MP23, those strains could no longer degrade mecoprop. This compelling result suggests that plasmid DNAs, in this case, conferred the ability to degrade the herbicide. The isolates MP13, MP15, and MP24 were identified as the same strain; however, they exhibited different plasmid profiles. This indicates that these isolates acquired dif-ferent mecoprop-degradative plasmids in different soils through natural gene transfer.

• Korean Journal of Plant Tissue Culture
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• v.21 no.5
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• pp.299-302
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• 1994

Immature zygotic embryos (up to 4mm in length) were cultured on MS medium supplemented with 0.5 to 8mg/L 2,4-D. Up to 87% of them formed somatic embryos on the plumule without producing an intervening callus. The site of somatic embryo formation was confirmed by culturing plumule explants, which consisted of shoot apical meristem domes with 1 or 2 leaf primordia excised from 2-week-old seedlings. When the concentration of 2,4-D was increased over 4 mg/L, the plumule explants produced nonembryogenic calli only, whereas the distal end of the cotyledons directly formed numerous somatic embryos at frequencies of up to 60%. Upon transfer onto MS basal medium,2 out of 15 somatic embryos converted into plantlets. The plantlets were potted to a soil mixture and grown to maturity in a phytotron.

• Plant Biotechnology Reports
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• v.3 no.3
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• pp.251-257
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• 2009

Embryogenic callus was obtained from bulb segments of Iris pseudacorus on Murashige and Skoog (MS) medium with 2,4-dichlorophenoxyacetic acid (2,4-D) alone or in combination with kinetin. When early globular somatic embryos were subcultured onto MS medium with $4.52{\mu}M$ 2,4-D, high frequency of somatic embryogenesis was obtained. Deprivation of 2,4-D was required for maturation. Mature somatic embryos had an elongated scutellum with a notch on the base of scutellum. Separation of embryos from embryo clusters was necessary to enhance the frequency of germination. Germination was stimulated by separation of embryos from embryo clusters and transfer onto fresh half-strength MS medium with 3% sucrose. After acclimation in artificial soil in greenhouse for 2 months, 96.4% of plantlets survived.

• Plant Biotechnology Reports
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• v.2 no.1
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• pp.47-58
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• 2008

To select agronomically useful transgenic plants, a large number of transgenic events are initially produced, gene transfer confirmed, and advanced to obtain homozygous lines for testing in field trials. Direct in planta assays for identifying the transgene carriers in the segregating progeny are based on the activity of selectable marker gene and are easy, simple and inexpensive. For this purpose, expression of bar gene as measured by tolerance to damage by glufosinate ammonium, the active ingredient in the herbicide BASTA, was investigated. Dose damage curves were generated by leaf paint tests with BASTA on four genotypes of sorghum. Transgenic plants were characterized in terms of sensitivity to the concentration of glufosinate ammonium. In transgenics, symptoms of BASTA swab tests at different growth stages and PCR analysis for cry1B were carried out and correlated. Germination tests could not be employed for large scale evaluation of transgenic progeny because of mortality of tolerant seedlings after transplantation to soil. Based on the above findings, a simple, inexpensive, time-saving, two-step scheme for effective evaluation of transgenics and their progeny containing bar gene as selection marker using BASTA swab tests is described.

• Journal of Radiation Industry
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• v.6 no.1
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• pp.1-9
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• 2012

In spite of colossal efforts taken for safe handling and storage of radioactive waste, the uncontrolled release of radiocesium ($^{137}Cs$ and $^{134}Cs$ isotopes) into the natural environment is inevitable. $^{137}Cs$ is of particular concern because of its long half-life, ability to transfer into biota through food chains, as well as its great mobility, bioavailability, and chemical and ecophysiological similarity with potassium. Radiocesium is released anthropogenically into the environment. Mushrooms are known for their ability to accumulate radionuclides, particularly radiocesium, which is heterogeneously distributed in the individual parts of mushrooms, and it is found that mushrooms are a hyper-accumulator of radiocesium from their environment than other vegetation. Mushrooms play a major role in the mobilization, accumulation, and translocation of cesium, i.e., decontamination of soils (mycoextraction) polluted with cesium radioisotopes, and this capacity appears to be a relevant bioindicator of cesium contamination in the environment. Moreover, the extension of mycelium into the soil makes the use of mushrooms as bioindicators of radiocesium possible. This paper reviews the potential of mushrooms in the accumulation of radiocesium from the environment, and dissertates the salient features to support the employment of mushrooms in environmental biomonitoring as a sensitive bioindicator of radiocesium contamination.

• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.7-7
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• 2015

가뭄 및 홍수 등 재해를 방지하고 효율적인 물 관리를 위해서는 지표와 대기 사이에 이루어지는 수문기상 요소의 정량화가 필요하다. 수문기상요소는 관측을 통해 파악하는 것이 가장 정확하지만 광범위한 지역에 대한 관측은 한계가 있으므로 일반적으로 지면모델(Land Surface Model)을 많이 이용한다. 본 연구에서 Noah LSM(Noah Land Surface Model)과 TOPLATS(TOPmodel based Land-Atmosphere Transfer Scheme) 및 DHSVM(Distributed Hydrology Soil Vegetation Model)의 세 모델을 활용하여 안동댐 유역의 수문기상정보를 산출하고 관측자료와 검증함으로 각 모델의 특성을 분석하자 한다. 본 연구에서 사용된 관측자료는 국립기상과학원에서 운영중인 안동댐 유역 플럭스타워의(A6, A7) 지표근처 기상장과 에너지 요소이다. '13년 10월부터 '14년 11월까지 기간에 대해 각 지점에서 관측된 현열 및 잠열 플럭스의 품질관리를 수행하였으며, 이 자료를 본 연구의 검증자료로 활용하였다. 각 모델을 강제하기 위한 지표근처 기상자료는 두 지점에서 관측된 기온, 풍향 풍속, 상대습도, 강수, 지중온도 및 장 단파 복사량이며, 각 모델에서 산출된 잠열 및 현열 플럭스, 토양수분과 증발산량을 관측값과 비교 검증하였다. 본 연구결과는 한국수자원학회 학술발표회를 통하여 소개될 예정이며, 향후 멀티모델 앙상블 시스템 구축에 기초자료로 활용될 것으로 기대된다.

• Korean Journal of Environmental Agriculture
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• v.25 no.4
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• pp.323-330
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• 2006

This experiment was conducted to investigate heavy metal transition and bioavailability from soil to the edible pare of water dropwort near industrial complex. The soils were collected from the paddies cultivating water dropwort stream sediments, and background soils near industrial complex. The pH values, organic matter, Av. $P_2O_5$, Ex. Ca content of paddy soils were higher than those measured for nor-contaminated paddy fields in 2003. The contents of Cd and Cu was higher than those of standard level for soil contamination by Soil Environmental Conservation Act in Korea. The pollution index in stream sediments were higher than those of paddies cultivating water dropwort. The geoaccumulation index of heavy metals in paddy soils and stream sediment were in the order Cu>Cd>Ni>Zn>Pb. The rates of 0.1N-HCl extractable heavy metals to total contents in soils were in the order Cd>Cu>Zn>Ni>Pb. In case of Cd and Ni in paddy soils near industrial complex, 0.1N-HCl extractable heavy metals and total content were highly correlated with each other. Heavy metal contents in mot parts were higher than those in top pare of water dropwort. The Zn and Cu transfer factor from soil to the top pare of water dropwort were higher than those of other heavy metals. The bioavailability of water dropwort varied considerably between the different parts and heavy metals. Cd, Cu and Ni contents in water dropwort were correlated with each elements in paddy soils.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.10 no.1
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• pp.100-112
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• 2005

Soil temperature was measured from the surface to 40 cm depth at three stations with different heights in tidal flat of Gomso Bay, west coast of Korea, for one month in every season 2004 to examine the thermal structure and the variation. Mean temperature in surface layer was higher in summer and lower in winter than in lower layer, reflecting the seasonal variation of vertically propagating structure of temperature by heating and cooling from the tidal flat surface. Standard deviation of temperature decreased from the surface to lower layer. Periodic variations of solar radiation energy and tide mainly caused short term variation of soil temperature, which was also intermittently influenced by precipitation and wind. Time series analysis showed the power spectral energy peaks at the periods of 24, 12 and 8 hours, and the strongest peak appeared at 24 hour period. These peaks can be interpreted as temperature waves forced by variations of solar radiation, diurnal tide and interaction of both variations, respectively. EOF analysis showed that the first and the second modes resolved 96% of variation of vertical temperature structure. The first mode was interpreted as the heating antl cooling from tidal flat surface and the second mode as the effect of phase lag produced by temperature wave propagation in the soil. The phase of heat transfer by 24 hour period wave, analyzed by cross spectrum, showed that mean phase difference of the temperature wave increased almost linearly with the soil depth. The time lags by the phase difference from surface to 10, 20 and 40cm were 3.2,6.5 and 9.8 hours, respectively. Vertical thermal diffusivity of temperature wave of 24 hour period was estimated using one dimensional thermal diffusion model. Average diffusivity over the soil depths and seasons resulted in $0.70{\times}10^{-6}m^2/s$ at the middle station and $0.57{\times}10^{-6}m^2/s$ at the lowest station. The depth-averaged diffusivity was large in spring and small in summer and the seasonal mean diffusivity vertically increased from 2 cm to 10 cm and decreased from 10 cm to 40 cm. Thermal propagation speeds were estimated by $8.75{\times}10^{-4}cm/s,\;3.8{\times}10{-4}cm/s,\;and\;1.7{\times}10^{-4}cm/s$ from 2 cm to 10 cm, 20 cm and 40 cm, respectively, indicating the speed reduction with depth increasing from the surface.

• Journal of Korean Tunnelling and Underground Space Association
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• v.18 no.5
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• pp.401-412
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• 2016

It is extremely difficult to apply conventional grouting methods to subsea tunnelling construction in the high water pressure condition. In such a condition, the rapid artificial freezing method can be an alternative to grouting to form a watertight zone around freezing pipes. For a proper design of the artificial freezing method, the influence of salinity on the freezing process has to be considered. However, there are few domestic tunnel construction that adopted the artificial freezing method, and influential factors on the freezing of the soil are not clearly identified. In this paper, a series of laboratory experiments were performed to identify the physical characteristics of frozen soil. Thermal conductivity of the frozen and unfrozen soil samples was measured through the thermal sensor adopting transient hot-wire method. Moreover, a lab-scale freezing chamber was devised to simulate freezing process of silica sand with consideration of the salinity of pore-water. The temperature in the silica sand sample was measured during the freezing process to evaluate the effect of pore-water salinity on the frozen rate that is one of the key parameters in designing the artificial freezing method in subsea tunnelling. In case of unfrozen soil, the soil samples saturated with fresh water (salinity of 0%) and brine water (salinity of 3.5%) showed a similar value of thermal conductivity. However, the frozen soil sample saturated with brine water led to the thermal conductivity notably higher than that of fresh water, which corresponds to the fact that the freezing rate of brine water was greater than that of fresh water in the freezing chamber test.