• Korean Journal of Microbiology
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• v.45 no.2
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• pp.140-147
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• 2009

In this study, anaerobic enrichment cultivation was performed with the sediments from the Gimpo and Inchon areas. Lactate as an electron donor and PCE as an electron acceptor was injected into the serum bottle with an anaerobic medium. After the incubation of 8 weeks, the reductive dechlorination of PCE was observed in 7 sites among 16 sites (43%). Three enrichment cultures showed completely dechlorination of PCE to ethene, while four enrichment culture showed transformation of PCE to cis-DCE. The bacterial community structure was analyzed by PCR-DGGE. Dechlorinating bacteria were detected by species-specific primers. The dominant species in seven anaerobic enrichments were found to belong to the genus of Dehalococcoides sp. and Geobacter sp., and Dehalobacter sp.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.3
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• pp.292-299
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• 2006

Batch experiments were performed to evaluate the effects of the electron donor dosage and the initial biomass on the reductive dechlorination of perchloroethene(PCE) with benzoate as an electron donor. When benzoate was added less than the theoretical requirement for dechlorination(electron donor/acceptor ratio=0.5 and 1), the dechlorination efficiency increased from 71% to 94.3% with the increase in benzoate dosage, but the fraction of electron equivalent utilized for dechlorination decreased from 92.7% to 79.6%. Methane production was observed when the hydrogen concentration was higher than the threshold value(10 nM) after PCE and trichloroethene (TCE) were reduced to cis-1,2-dichloroethene(cDCE). When benzoate was added more than the theoretical requirement, the residual hydrogen converted into methane after the completion of dechlorination. The increase in the seeding biomass shortened the lag time for dechlorination, but it did not affect the maximum dechlorination rate as it was mainly governed by the benzoate fermentation rate. When the seeding biomass concentration was high, active dechlorination during the early period increased dechlorination efficiency while decreasing methane production.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.16 no.12
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• pp.1336-1347
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• 1991

In this paper, The PC interface for packet terminal of ISDN is designed and implemented in order to build packet communication networks which share computer resources and exchange informations between computer in the ISDN environment. The PC interface for packet terminal of ISDN constitutes S interface handler part which controls functions of ISDN layer1 and layer 2, constitutes packet handler part which controls services of X.25 protocol in the packet level.Where, The function of ISDN layer1 provides rules of electrical and mechanical characteristics, services for ISDN layer 2. The function of ISDN layer 2 provides function of LAPD procedure, services for X.25 The X.25 specifies interface between DCE and DTE for terminals operrating in the packet mode. The S interface handler part is orfanized by Am 79C30 ICs manufactured by Advanecd Micro Devices. ISDN packet handler part is organiged by AmZ8038 for FIFO for the purpose of D channel. The common signal procedure for D channel is controlled by Intel's 8086 microprocessor. The S interface handler part is based on ISDN layer1,2 is controlled by mail box in order to communicate between layers. The ISDN packet handler part is based on module in the X.25 lebel. The communication between S interface handler part and ISDN packet handler part is organized by interface controller.

• Journal of Soil and Groundwater Environment
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• v.11 no.5
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• pp.35-42
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• 2006

The following results were obtained in the reductive degradation of hexachloroethane (HCA), and surface characteristics by using iron sulfide ($FeS,\;FeS_{2}$) mediators. HCA was degraded to pentachloroethane (PCA), tetrachloroethylene(PCE), trichloroethylene(TCE) and cis-l,2-dichloroethylene (cis-1,2-DCE) by complicated pathways such as hydrogenolysis, dehaloelimination and dehydrohalogenation. FeS had more rapid degradation rates of organic solvent than $FeS_{2}$. In liquidsolid reaction, the reaction rates of organic solvents were investigated to explain surface characteristics of FeS and $FeS_{2}$.. To determine surface characteristics of FeS and $FeS_{2}$, the specific surface area and surface potential of each mineral was determined and the hydrophilic site ($N_{s}$) was calculated. The specific surface area ($107.0470m^{2}/g\;and\;92.6374m^{2}/g$) and the $pH_{ZPC}$ of minerals ($FeS\;PH_{ZPC}=7.42,\;FeS_{2},\;PH_{ZPC}=7.80$) were measured. The results showed that the Ns of FeS and $FeS_{2}$ were $0.053\;site/mm^{2}\;and\;0.205\;site/mm^{2}$, respectively. $FeS_{2}$ had more hydrophilic surface than FeS. In other words, FeS have more hydrophobic surface site than $FeS_{2}$.

• Journal of Soil and Groundwater Environment
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• v.17 no.5
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• pp.49-55
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• 2012

A 1.28 L-batch reactor and continuous-flow stirred tank reactor (CFSTR) fed with formate and trichloroethene (TCE) were operated for 120 days and 56 days, respectively, to study the effect of formate as electron donor on anaerobic reductive dechlorination (ARD) of TCE to cis-1,2-dichloroethylene (c-DCE), vinyl chloride (VC), and ethylene (ETH). In batch reactor, injected 60 ${\mu}mol$ TCE was completely degraded in the presence of 20% hydrogen gas ($H_2$) in less than 8 days by anaerobic dechlorination mixed-culture (300 mg-soluble protein), Evanite Culture with ability to completely degrade tetrachloroethene (PCE) and -TCE to ETH under anaerobic conditions. Once the formate was used as electron donor instead of hydrogen gas in batch or chemostat system, the TCE-dechlorination rate decreased and acetate production rate increased. It indicates that the concentration of hydrogen produced in both systems is possibly more close to threshold for homoacetogenesis process. Soluble protein concentration of Evanite culture during the batch test increased from 300 mg to 688 mg for 120 days. Through the protein monitoring, we confirmed an increase of microbial population during the reactor operation. In CFSTR test, TCE was fed continuously at 9.9 ppm (75.38 ${\mu}mol/L$) and the influent formate feed concentration increased stepwise from 1.3 mmol/L to 14.3 mmol/L. Injected TCE was accumulated at 18 days of HRT, but TCE was completely degraded at 36 days of HRT without accumulation of the injected-TCE during the left of experiment period, getting $H_2$ from fermentative hydrogen production of injected formate. Although c-DCE was also accumulated for 23 days after beginning of CFSTR operation, it reached steady-state in the presence of excessive formate. We also evaluated microbial dynamic of the culture at different chemical state in the reactor by DGGE (denaturing gradient gel electrophoresis).

• 한국노년학
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• v.38 no.3
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• pp.409-433
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• 2018

The purpose of this study is to examine the effect of contact with the elderly in a daily life on children's ageist attitude. Acknowledging the people's tendency to report in socially appropriate ways to the explicit attitude measurement, implicit measurement is introduced, and relation with the daily contact with elderly(DCE) is analyzed. The research question are as follows: 1) Are these two attitudes explained by different factors? 2) Can DCE alleviate both children's implicit and explicit ageist attitude? 3) How do the contact with grandparent and neighboring elderly affect the children's explicit and implicit ageist attitude? Data was collected from 503 fourth to sixth grade elementary school children. Child-Age Implict Association Test is used to measure implicit ageist attitude. Multinominal logistic analysis and ordered logistic analysis was applied. Followings are the main results: First, explicit and implicit ageist attitudes are found to be related with different predictors. Second, Elderly contact seems to lighten children's ageist attitude overall. Third, the effects of grandparental contact and the neighboring elderly contact on two different ageism were different. While the effect of elderly neighbor contact is limited to the expression of ageism, grandparental contact has a influence not only on the explicit but also on the implicit ageism, even though the effect on implicit attitude is limited in extent. Forth, not the quality of contact but the quantity of it was related to implicit ageist attitude. This result contradicts conventional idea of Intergroup Contact Theory. In the further research, the predictor of implicit ageist attitude need to be throughly examined.

• Investigative Magnetic Resonance Imaging
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• v.23 no.2
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• pp.125-135
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• 2019

Purpose: The purpose of this study was to evaluate dynamic contrast-enhanced breast magnetic resonance imaging (DCE-MRI), and diffusion-weighted imaging (DWI) variables, for axillary lymph node (ALN) metastasis in the early stage of breast cancer. Materials and Methods: January 2011-April 2015, 787 patients with early stage of breast cancer were retrospectively reviewed. Only cases of invasive ductal carcinoma, were included in the patient population. Among them, 240 patients who underwent 3.0-T DCE-MRI, including DWI with b value 0 and $800s/mm^2$ were enrolled. MRI variables (adjacent vessel sign, whole-breast vascularity, initial enhancement pattern, quantitative kinetic parameters, signal enhancement ratio (SER), tumor apparent diffusion coefficient (ADC), peritumoral ADC, and peritumor-tumor ADC ratio) clinico-pathologic variables (age, T stage, multifocality, extensive intraductal carcinoma component (EIC), estrogen receptor, progesterone receptor, HER-2 status, Ki-67, molecular subtype, histologic grade, and nuclear grade) were compared between patients with axillary lymph node metastasis and those with no lymph node metastasis. Multivariate regression analysis was performed, to determine independent variables associated with ALN metastasis, and the area under the receiver operating characteristic curve (AUC), for predicting ALN metastasis was analyzed, for those variables. Results: On breast MRI, moderate or prominent ipsilateral whole-breast vascularity (moderate, odds ratio [OR] 3.45, 95% confidence interval [CI] 1.28-9.51 vs. prominent, OR = 15.59, 95% CI 2.52-96.46), SER (OR = 1.68, 95% CI 1.09-2.59), and peritumor-tumor ADC ratio (OR = 6.77, 95% CI 2.41-18.99), were independently associated with ALN metastasis. Among clinico-pathologic variables, HER-2 positivity was independently associated, with ALN metastasis (OR = 23.71, 95% CI 10.50-53.54). The AUC for combining selected MRI variables and clinico-pathologic variables, was higher than that of clinico-pathologic variables (P < 0.05). Conclusion: SER, moderate or prominent increased whole breast vascularity, and peritumor-tumor ADC ratio on breast MRI, are valuable in predicting ALN metastasis, in patients with early stage of breast cancer.

• Tunnel and Underground Space
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• v.34 no.3
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• pp.208-217
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• 2024

There is so much research effort for developing and implementing deep learning-based surveillance systems to manage health and safety issues in construction sites. Especially, the development of deep learning-based object detection in various environmental changes has been progressing because those affect decreasing searching performance of the model. Among the various environmental variables, the accuracy of the object detection model is significantly dropped under low illuminance, and consistent object detection accuracy cannot be secured even the model is trained using low-light images. Accordingly, there is a need of low-light enhancement to keep the performance under low illuminance. Therefore, this paper conducts a comparative study of various deep learning-based low-light image enhancement models (GLADNet, KinD, LLFlow, Zero-DCE) using the acquired construction site image data. The low-light enhanced image was visually verified, and it was quantitatively analyzed by adopting image quality evaluation metrics such as PSNR, SSIM, Delta-E. As a result of the experiment, the low-light image enhancement performance of GLADNet showed excellent results in quantitative and qualitative evaluation, and it was analyzed to be suitable as a low-light image enhancement model. If the low-light image enhancement technique is applied as an image preprocessing to the deep learning-based object detection model in the future, it is expected to secure consistent object detection performance in a low-light environment.

• 한국생물공학회:학술대회논문집
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• 2001.11a
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• pp.77-80
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• 2001

Groundwater, contaminated predominantly with aromatic compounds and chlorinated ethylene, could be biologically treated in a fluidized-bed reactor with immobilized cells. The decomposition efficiency for the aromatics was over 90% at the retention time of 2.5 h. The chlorinated ethylenes, especially trichloroethylene (TCE) and cis-dichloroethylene (DCE), could be decomposed only insufficiently. No anaerobic methane formation was observed for this groundwater even at a very low dissolved oxygen (DO) concentration of 0.75 mg/L. The variation of DO concentration resulted in an optimal value of 1.5 mg/L. The recycle of air waste could increase the utilization of oxygen. The amount of low boiling pollutants stripped out remained constant with the recycle, while for the higher boiling pollutants the stripping slightly increased. Using air instead of oxygen increases the flow rate of air waste, which is connected to a higher stripping of pollutants. In this investigation, the pollutant concentration in the air waste remained constant. The stripping of main pollutants did not exceed 0.3 %.

• Journal of Soil and Groundwater Environment
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• v.21 no.6
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• pp.101-113
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• 2016

To properly manage and remediate groundwater contaminated with chlorinated hydrocarbons such as trichloroethylene (TCE), it is necessary to assess natural attenuation processes of contaminants in the aquifer along with investigation of contamination history and aquifer characterization. This study evaluated natural attenuation processes of TCE at an industrial site in Korea by delineating hydrogeochemical characteristics along the flow path of contaminated groundwater, by calculating reaction rate constants for TCE and its degradation products, and by using geochemical and reactive transport modeling. The monitoring data showed that TCE tended to be transformed to cis-1,2-dichloroethene (cis-1,2-DCE) and further to vinyl chloride (VC) via microbial reductive dechlorination, although the degree was not too significant. According to our modeling results, the temporal and spatial distribution of the TCE plume suggested the dominant role of biodegradation in attenuation processes. This study can provide a useful method for assessing natural attenuation processes in the aquifer contaminated with chlorinated hydrocarbons and can be applied to other sites with similar hydrological, microbiological, and geochemical settings.