• Journal of Life Science
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• v.22 no.8
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• pp.999-1008
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• 2012

The circadian clock is a self-sustaining 24-hour timekeeper that allows organisms to anticipate daily-changing environmental time cues. Circadian clock genes are regulated by a transcriptional-translational feedback loop. In Arabidopsis, LATE ELONGATED HYPOCOTYL (LHY) and CIRCADIAN CLOCK-ASSOCIATED 1 (CCA1) transcripts are highly expressed in the morning. Translated LHY and CCA1 proteins repress the expression of the TIMING OF CAB EXPRESSION 1 (TOC1) transcripts, which peaks in the evening. The TOC1 protein elevates the expression of the LHY and CCA1 transcripts, forming a negative feedback loop that is believed to constitute the oscillatory mechanism of the clock. In mammals, the transcription factor protein CLOCK, which is a central component of the circadian clock, was reported to have an intrinsic histone acetyltransferase (HAT) activity, suggesting that histone acetylation is important for core clock mechanisms. However, little is known about the components necessary for the histone acetylation of the Arabidopsis clock-related genes. Here, I report that DET1 (De-Etiolated1) functions as a negative regulator of a key component of the Arabidopsis circadian clock gene LHY in constant dark phases (DD) and is required for the down-regulation of LHY expression through the acetylation of histone 3 (H3Ac). However, the HATs directly responsible for the acetylation of H3 within LHY chromatin need to be identified, and a link connecting the HATs and DET1 protein is still absent.

• Journal of Life Science
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• v.21 no.6
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• pp.819-828
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• 2011

To inspect norovirus contamination of groundwater in south eastern areas of Korea, a systematic survey of groundwater in Busan, Ulsan, and Gyeongsangnam-do was performed for two years from 2009 to 2010. For this purpose, we first optimized the nested reverse transcription-PCR condition by designing two sets of primers for the detection of norovirus genogroups, GI and GII. Of 145 samples, 21 (25.9%) and 15 (23.4%) were norovirus positive in the dry season (April to June) and wet season (July to August), respectively. The detection frequencies of norovirus in Busan, Ulsan, and Gyeongsangnam-do were 15%, 7%, and 32%, respectively, reflecting a geographical difference in their distribution. The GI and GII isolates were 5 and 31, respectively, indicating the prevalence of GII in the tested areas. According to phylogenetic analysis of their nucleotide sequences, all of the GI isolates were identified to genotype GI.5 whilst the GII isolates were divided into two genotypes, GII.3 and GII.4. Neither physical-chemical parameters such as pH, temperature, oxidation-reduction potential, and dissolved oxygen, nor microbial indicators of water quality such as total bacteria, total coliforms, and Escherichia coli were statistically correlated with contamination of norovirus in the groundwater. Interestingly, however, the presence of norovirus was closely correlated with low turbidity (<0.50 NTU). The present study suggests that periodical monitoring of norovirus in groundwater is necessary to prevent epidemic waterborne diseases and to secure better sanitary conditions for public health.

• Korean Journal of Food Science and Technology
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• v.31 no.3
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• pp.823-830
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• 1999

The suppressing effects of crude extracts of three Korean teas, persimmon leaf tea extract (PLTE), green tea extract (GTE) and oolong tea extract (OTE), were studied on the induction of sister chromatid exchange (SCE) in cultured Chinese hamster ovary cells. When cells were treated with tea extract after mitomycin C (MMC) treatment, the frequency of MMC-induced SCEs were decreased at the high concentration $(1000\;{\mu}g/mL)$ of PLTE in the presence of S9 mix and at low concentrations $(20{\sim}80\;{\mu}g/mL)$ of PLTE in the absence of S9 mix, Whereas GTE and OTE showed suppressing effects on the MMC-induced SCEs at low concentrations $(10{\sim}20\;{\mu}g/mL)$ for OTE and $160\;{\mu}g/mL$ for GTE only in the presence of S9 mix. MMC-induced SCEs were decreased by post-treatment with each tea extracts with S9 mix in the G1 phase of the cell cycle. These results suggest that PLTE, GTE and OTE could have bio antimutagenic activities, and also suggest that PLTE might have unknown antimutagenic components which would be responsible for the inhibitory effect against direct acting mutagenicity.

• Korean Journal of Remote Sensing
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• v.34 no.2_2
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• pp.313-326
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• 2018

This paper introduces core techniques on ship detection and tracking based on a compact HF radar platform which is necessary to establish a wide-area surveillance network. Currently, most HF radar sites are primarily optimized for observing sea surface radial velocities and bearings. Therefore, many ship detection systems are vulnerable to error sources such as environmental noise and clutter when they are applied to these practical surface current observation purpose systems. In addition, due to Korea's geographical features, only compact HF radars which generates non-uniform antenna response and has no information on target information are applicable. The ship detection and tracking techniques discussed in this paper considers these practical conditions and were evaluated by real data collected from the Yellow Sea, Korea. The proposed method is composed of two parts. In the first part, ship detection, a constant false alarm rate based detector was applied and was enhanced by a PCA subspace decomposition method which reduces noise. To merge multiple detections originated from a single target due to the Doppler effect during long CPIs, a clustering method was applied. Finally, data association framework eliminates false detections by considering ship maneuvering over time. According to evaluation results, it is claimed that the proposed method produces satisfactory results within certain ranges.

• Journal of Conservation Science
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• v.29 no.1
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• pp.55-67
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• 2013

This study focused on analysis condition and application method of the passive infrared thermography according to the direction and time to nondestructively detect the blistering zone of stone cultural heritage. As a result, the passive thermographic images showed different temperature characteristics by time because it sensitively reacts to air temperature, insolation and sunshine direction. In particular, the insolation and sunshine direction, which are periodically changed from 6:00 to 17:00, irregularly made surface temperature. In addition, surface temperature differences were brought on fresh zones and blistering zones except specific time since blistering causes erratic thermal transfer. As a result of examining the detection characteristics of blistering by time, the blistering was well detected between 9:00 and 10:00 when there was rapid increase in air temperature and insolation in all direction except the north. However, this study isn't considered effects of four seasons because it is carried out in autumn, and the passive thermography has difficulty to analyze the quantitative area of blistering zone. Therefore, an additional study for synthetic consideration of the passive thermography analysis about four seasons and quantitative modeling of blistering zone using the active thermography are needed.

• Korean Journal of Environmental Biology
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• v.32 no.4
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• pp.363-370
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• 2014

Various ecosystem carry out fundamental function of material circulation and energy flow through interrelationship with many environmental factors. Therefore, it is crucial to scientifically understand the value of nature to deduce correlation between environmental factor and change of ecosystem function. In this study, we determined the accumulated ecosystem carbon and characteristics of soil respiration on grassland vegetation in Namahangang basin in Namhangang Basin. It was found that the rate of soil respiration was highly correlated with the soil temperature in all communities. The measured soil respiration rates were $1,539mgCO_2\;m^{-2}h^{-1}$, $1,200mgCO_2\;m^{-2}h^{-1}$, $1,215mgCO_2\;m^{-2}h^{-1}$ in Miscanthus sacchariflorus, Phragmites japonica, Salix koreensis communities, respectively. Also, carbon quantities accumulated in litter and soil layers were $40.6tCha^{-1}$ (1.9+38.7), $46.9tCha^{-1}$ (43.0+3.9), $31.2tCha^{-1}$ (28.9+2.3) in M. sacchariflorus, P. japonica, S. koreensis communities, respectively.

• The Journal of Engineering Geology
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• v.18 no.3
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• pp.331-338
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• 2008

A new ground water sampler was developed and evaluated for target depth sampling under most rigorous field conditions. This new concept sampler comprises an air-cylinder, a hypodermic needle and a sampling bottle. Pressurized air or nitrogen gas can be used as a mechanical power source to operate the sampler. The air-cylinder is used to jab the hypodermic needle into the rubber cap of the sampling bottle. The hypodermic needle functions as a pathway to inject groundwater into the sampling bottle. Field test was conducted in a seawater intrusion monitoring well located at Handong district of Jeju Island. Water qualities in this well are periodically changed from the effects of sea water. Water sampling fir the same target depth in this well were tried at various times, and variations in electrical conductivity and pressure at the inside and outside of the sampler were measured using CTD divers. We found that the device could collect water samples only when it was actuated, and the pattern and range of variations in electrical conductivities and pressures measured at the inside and outside of the sampler were nearly identical. These results indicate that water samples using the sampler presented in this study represent correctly water qualities in which the samplings were made at a specific target depth in a well.

• Journal of Korean Society for Geospatial Information Science
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• v.23 no.1
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• pp.113-121
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• 2015

Remote sensing technology using a multi-spectral satellite imagery can be utilized for the analysis of urban heat island effect in large area. However, weather condition of Korea mostly has a lot of clouds and it makes periodical observation using time-series of satellite images difficult. For this reason, we proposed the analysis of urban heat island effect using time-series of Landsat TM images and ATC model. To analyze vegetation condition and urbanization, NDVI and NDBI were calculated from Landsat images. In addition, land surface temperature was calculated from thermal infrared images to estimate the parameters of ATC model. Furthermore, the parameters of ATC model were compared based on the land cover map created by Korean Ministry of Environment to analyze urban heat island effect relating to the pattern of land use and land cover. As a result of a correlation analysis between calculated spectral indices and parameters of ATC model, MAST had high correlation with NDVI and NDBI (-0.76 and 0.69, respectively) and YAST also had correlation with NDVI and NDBI (-0.53 and 0.42, respectively). By comparing the parameters of ATC model based on land cover map, urban area had higher MAST and YAST than agricultural land and grassland. In particular, residential areas, industrial areas, commercial areas and transportation facilities showed higher MAST than cultural facilities and public facilities. Moreover, residential areas, industrial areas and commercial areas had higher YAST than the other urban areas.

• Microbiology and Biotechnology Letters
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• v.33 no.3
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• pp.169-177
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• 2005

This study focuses on investigating roles of microorganisms in decontamination of reed rhizosphere in Sunchon Bay, Korea, which is considered one of the marsh and mud environment severely affected by human activities such as agriculture and fisheries. In general, the bay is known to play the role of the buffering zone to reduce the sudden impact or change by environmental stresses. In our initial efforts to elucidate the microbial functions in decontamination process in reed rhizosphere, pure bacteria capable of degrading aromatic hydrocarbons were isolated from reed (Phragmites communis) rhizosphere of Sunchon bay by enrichment culture using either benzene, toluene, ethylbenzene, or xylene (BTEX) as a sole source of carbon and energy. Measurement of the rates of BTEX degradation and cell growth during the incubation in BTEX media under several temperature conditions demonstrated maximized degradation of BTEX at $37^{\circ}C$ in both strains. Both strains were also resistant to all the heavy metals and antibiotics tested in this study, as well as they grew well at $42^{\circ}C$. Identification of the isolates based on 16S rRNA gene sequences, and a variety of phenotypic and morphologic properties revealed that the two strains capable of BTEX catabolism were among Microbacterium sp., and Rhodococcus sp. with over $95{\%}$ confidence, designated Microbacterium sp. EMB-1 and Rhodococcus sp. EMB-2, respectively This result suggested that in the rhizosphere of reed, one of major salt marsh plants they might play an important roles in decontamination process of reed rhizosphere contaminated with petroleum such as BTEX.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.17 no.4
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• pp.259-268
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• 2005

There has been a growing interest in the elimination of anoxic layer in the Youngsan River Estuarybecause the anoxic water mass caused mainly by the inflow of fresh water from the sea wall might cause the mass reduction of benthos during summer. An ocean outfall system to discharge treated wastewater into sea water may be used as one of the effective and economical ways to eliminate the anoxic layer. The suitable ocean outfall design is generally proposed for the prediction of the buoyant jet behavior in the near field. The parameters including CTD and current data are taken into account f3r more reliable buoyant jet behavior calculation. One of the numerical models, CORMIX 1, approved by EPA is used herein for the prediction of the trajectorial variation of the cross-sectional salinity and DO concentration distribution on the calculated buoyant jet boundary according to the tidal periods. On the basis of the results, it is suggested that the single port outfall is a useful system to eliminate the anoxic layer. Proper strategies are also proposed for achieving desirable ambient conditions.