• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2001.04a
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• pp.120-123
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• 2001

To evaluate the biodegradability of contaminants in an aquifer, computer modeling with RT3D model (Clement, 1997) was used. The RT3D model simulates the biodegradation of organic contaminants using a number of aerobic and anaerobic electron acceptors. The RT3D model was applied to a well-studied petroleum hydrocarbon plume in a shallow unconfined aquifer in Uiwang, Korea. The results of this study demonstrate tile importance of biodegradation processes in the monitored natural attenuation and in reducing contaminant concentrations in a shallow aquifer. The modeling results tell that the amount of electron acceptors is the key factor affecting biodegradation of TEX, the petroleum hydrocarbon contaminant in shallow groundwater

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.04a
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• pp.430-433
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• 2003

Nitrogen pollution in urban and rural groundwater is a common problem and poses a major threat to drinking water supplies based on groundwater. In this work, the kinetics of nitrification-denitrification coupled reactions are modeled and new reaction modules for the RT3D code describing the fate and transport of nitrogen species, dissolved oxygen, dissolved organic carbon, and biomass are developed and tested. The proposed nitrogen transformations and transport model showed very good match with the results of other public codes.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2002.04a
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• pp.183-186
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• 2002

The objective of this study is to predict behavior of a contaminant plume and concentration of contaminants in soil through tile relations between the concentrations of contaminants in groundwater and in soil on the shallow sandy aquifer contaminated with petroleum hydrocarbons. The current state of the plume and its fate in the study area was simulated by using the MODFLOW-RT3D model and geochemical parameters of grounwater had been monitored and measured during 3 years (1999~2001). The relations between the concentrations of contaminants in each medium were taken from the investigation of site characterization conducted in 1999. Simulation results showed the center of the plume would migrate 407m twenty years later. At that time, the concentration would be decreased down to about 26 mg/$\ell$(93%). In comparison TEX concentration in the groundwater with that in the soil, the value of correlation coefficient (r=0.876) was as high as it could be used. Based on the high r-value, the linear equation was obtained from regression analysis. The results of model simulation by RT3D engine showed that the highest TEX concentration in the groundwater would be 58.8 mg/$\ell$ 16 years later, and then the TEX concentration in soil would be below the alarming level (80 mg/kg) of regulation criteria.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2005.04a
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• pp.393-396
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• 2005

The reactive transport model on the biologically mediated sequential nitrate transformation and its subsequent transport was developed and tested. This model was coded as a reaction module within the RT3D framework (Clement, 1997). Transports of the reasonable six mobile solutes (dissolved organic carbon, $O_2,\;{NO_3}^-,\;{NO_2}^-,\;N_2O,\;N_2$) and two immobile microbes were simulated. The simulation results gave a reasonable match with supposed transport pattern. For the next step, the developed model will be validated against experimental data.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2002.04a
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• pp.195-198
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• 2002

Nitrogen pollution in urban and rural groundwater is a common problem and poses a major threat to drinking water supplies based on groundwater. In this work, the kinetics of nitrification-denitrification coupled reactions are modeled and new reaction modules for the RT3D code (Clement, 1997) describing the fate and transport nitrogen species, dissolved oxygen, dissolved organic carbon, and biomass are developed. The proposed nitrogen transformations and transport model showed very good match with results of a conceptual model. However, the model simulation results for the major reactive species should be tested for validation using experimental and field data.

• Journal of Korean Neurosurgical Society
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• v.37 no.4
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• pp.287-292
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• 2005

Objective: Recent clinical studies have demonstrated that intracisternal administration of recombinant tissue plasminogen activator(rt-PA) can facilitate the normal clearing of blood from the subarachnoid space. Urokinase, a first generation fibrinolytic agent, has been used to liquify such clots with some success. Therefore, recombinant tissue plasminogen activator, a second generation fibrinolytic drug that may be safer and more effective, is studied to evaluate its dosage to lyse clots in vitro and reactivity in the brain parenchyme. Methods: Intracerebral hematomas were created by stereotactically injecting 2ml of clotted autogenous blood into the brain parenchyme of total 28 anesthetized adult cats (weighting 3.8 to 4.1 kg). The control animals (group A) received 1 ml of normal saline injected into the clots and the experimental animals received each 0.1 mg of rt-PA (group B), 0.5mg of rt-PA (group C) and 1 mg of rt-PA (group D) at 6 hours after the clot injection. Results: 1. The amount of remained clots after lysing the hematomas were as follows: $1.80{\pm}0.17ml$ in group A, $1.65{\pm}0.23ml$ in group B, $0.61{\pm}0.37ml$ in group C and $0.52{\pm}0.34$ in group D. The result indicated that hematomas in rt-PA treated groups (C & D) were lysed better than the control group. 2. At least 0.5mg of rt-PA should be required for the lysis of 2ml of hematomas. 3. Light microscopic examination revealed no histological evidence of hemorrhage in tissue sections from each brain. Conclusion: Recombinant tissue plasminogen activator may be safely and effectively employed for the lysis of intracerebral hematomas in animal model.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.04a
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• pp.318-322
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• 2004

Arsenic is a toxic and carcinogenic metalloid, whose sources in nature include mineral dissolution and volcanic eruption. Abandoned mines and hazardous waste disposal sites are another major source of arsenic contamination of soil and aquatic systems. To predict concentrations of the toxic inorganic arsenic in aqueous phase. the biogeochemical redox processes and transport behavior need to be studied together and be coupled in a reactive transport model. A new reaction module describing the fate and transport of inorganic arsenic species (As(II)), dissolved oxygen, nitrate, ferrous iron, sulfate, and dissolved organic carbon are developed and incorporated into the RT3D code.

• Radiation Oncology Journal
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• v.34 no.3
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• pp.230-238
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• 2016

Purpose: Hypoxia can impair the therapeutic efficacy of radiotherapy (RT). Therefore, a new strategy is necessary for enhancing the response to RT. In this study, we investigated whether the combination of nanoparticles and RT is effective in eliminating the radioresistance of hypoxic tumors. Materials and Methods: Gold nanoparticles (GNPs) consisting of a silica core with a gold shell were used. CT26 colon cancer mouse model was developed to study whether the combination of RT and GNPs reduced hypoxia-induced radioresistance. Hypoxia inducible $factor-1{\alpha}$ ($HIF-1{\alpha}$) was used as a hypoxia marker. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining were conducted to evaluate cell death. Results: Hypoxic tumor cells had an impaired response to RT. GNPs combined with RT enhanced anti-tumor effect in hypoxic tumor compared with RT alone. The combination of GNPs and RT decreased tumor cell viability compare to RT alone in vitro. Under hypoxia, tumors treated with GNPs + RT showed a higher response than that shown by tumors treated with RT alone. When a reactive oxygen species (ROS) scavenger was added, the enhanced antitumor effect of GNPs + RT was diminished. Conclusion: In the present study, hypoxic tumors treated with GNPs + RT showed favorable responses, which might be attributable to the ROS production induced by GNPs + RT. Taken together, GNPs combined with RT seems to be potential modality for enhancing the response to RT in hypoxic tumors.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.24 no.3
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• pp.384-390
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• 2020

The reverberation effect on the sound when producing movies or VR contents is a very important factor in the realism and liveliness. The reverberation time depending the space is recommended in a standard called RT60(Reverberation Time 60 dB). In this paper, we propose a scene recognition technique for automatic reverberation editing. To this end, we devised a classification model that independently trains color images and predicted depth images in the same model. Indoor scene classification is limited only by training color information because of the similarity of internal structure. Deep learning based depth information extraction technology is used to use spatial depth information. Based on RT60, 10 scene classes were constructed and model training and evaluation were conducted. Finally, the proposed SCR + DNet (Scene Classification for Reverb + Depth Net) classifier achieves higher performance than conventional CNN classifiers with 92.4% accuracy.

• Journal of the Korean Ceramic Society
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• v.20 no.2
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• pp.129-134
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• 1983

MgO.$Al_2O_3$ polycrstalline spinel powder was subjected to vaporization over the temperature range of 1150-130$0^{\circ}C$ under H2 atmosphere. Diffusion coefficient of oxygen ion through the spinel were calculated using the measure vaporization rates as follows : D=28.4 exp(-901500/RT) Reference data of the vaporization rates of MgO.$8Al_2O_3$ single crystal spinel were applied to the vaporiza-tion model proposed in this study and were calculated to give the oxygen ion diffusion coefficients over the tempera-ture 1700-195$0^{\circ}C$. The obtained diffusion coefficients are as follows: $D=3.20{\times}106$ exp(-155600/RT)