• Radiation Oncology Journal
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• v.8 no.1
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• pp.133-136
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• 1990

Intracavitary brachytherapy combined hypertermin for utero-conical cancer seems to be a promising method for salvage treatments in persistent tumors and inoperable or previously irradiated cervical recurrences. In order to heat the vaginal apex and uterus, powerfull conical antennas which are suitable for afterloading cervical applicator have been designed for use in conjuction with intracavitary radiation therapy. The antennas were constructed with conical conductive material to feed line and the effective lenght were designed proportional to microwave length, Power deposition profiles of 2450 MHz of conical antennas were studied in both phantom models and muscle tissue and compared to those of commonly used dipole antenna. Improvement of the heating pattern was found in both phantom and muscle tissue. The heating pattern produced by the conical antenna resembles an ellipsoid and then the temperature distribution in depth was extended to $2\~3\;cm$ from the effective antenna axis.

• Journal of the Korean Vacuum Society
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• v.2 no.2
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• pp.181-187
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• 1993

We have studied the anodic oxidation of silicon in the anisotropic etchant of EPW(Ethylenediamine, Pyrocatechol and Water) solution using the cyclic polarization technique. The samples have been characterized by means of X-ray photoelectron spectroscopy(XPS) and secondary ion mass spectrometry (SIMS). The results of cyclic polarization experiments show that the anodic oxides formed on p- and n-type silicon wafers break down at the same potential while breakdown does not occur up to open circuit potential in the case of $p^+$-Si. Strong etch-resistance of $p^+$-XPS. SIMS depth profiles suggest that the critical concentration of boron for etch-stop to occur appears to be much higher than what is widely believed.

• Korean Journal of Environmental Biology
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• v.29 no.1
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• pp.46-51
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• 2011

Distributional patterns of benthic microalgae were studied in the tidal flats of Saemangeum lake, Korea, from March 2007 to October 2009. As benthic microalgae of tidal flats of Saemangeum lake, 44 species belong to 5 classes were identified. Diatoms predominated the benthic microalgal flora with 75.0% of total species occurred. Dominant species were Achnanthes lanceolata, Aulacoseira granulata, Cymbella tumida, Fragilaria construens var. ventor, Melosira varians, Navicula cryptocephala, Navicula cryptocephala var. veneta, Nitzschia palea, and Paralia sulcata. The cell density and biomass of benthic microalgae were highest in 2009, and clear tendency of increment was observed at D1 and D2 sites. In vertical profiles, cell density and biomass of the benthic microalgae showed maximum cells and biomass at 0~1 mm depth of sediments from all sampled sites.

• Journal of The Korean Society of Agricultural Engineers
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• v.55 no.3
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• pp.91-104
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• 2013

The objectives of this study were to monitor and assess the environmental impacts of indirect wastewater reuse on water quality and soil in paddy fields. Yongin monitoring site (YI) irrigated from agricultural reservoir and Osan monitoring site (OS) irrigated with treated wastewater diluted with stream water were selected as control and treatment, respectively. Monitoring results for irrigation water quality showed a significant statistical difference in salinity, exchangeable cation and nutrients. Pond water quality showed a similar tendency with irrigation water except for the decreased difference in nutrients due to the fertilization impact. Soil chemical properties mainly influenced by fertilization activity such as T-N, T-P, and $P_2O_5$ were changed similarly in soil profiles of both monitoring sites, while the properties, EC, Ca, Mg, and Na, mainly effected by irrigation water quality showed a considerable change with time and soil depth in treatment plots. Heavy metal contents in paddy soil of both control and treatment did not exceed the soil contamination warning standards. This study could contribute to suggest the irrigation water quality standards and proper agricultural practices including fertilization for indirect wastewater reuse, although long-term monitoring is needed to get more scientific results.

• Geophysics and Geophysical Exploration
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• v.7 no.1
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• pp.14-18
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• 2004

High levels of ambient noise and safety factors often limit the use of 'active-source' seismic methods for geotechnical investigations in urban environments. As an alternative, shear-wave velocity-depth profiles can be obtained by treating the background microtremor wave field as a stochastic process, rather than adopting the traditional approach of calculating velocity based on ray path geometry from a known source. A recent field test in Melbourne demonstrates the ability of the microtremor method, using only Rayleigh waves, to resolve a velocity inversion resulting from the presence of a hard, 12 m thick basalt flow overlying 25 m of softer alluvial sediments and weathered mudstone. Normally the presence of the weaker underlying sediments would lead to an ambiguous or incorrect interpretation with conventional seismic refraction methods. However, this layer of sediments is resolved by the microtremor method, and its inclusion is required in one-dimensional layered-earth modelling in order to reproduce the Rayleigh-wave coherency spectra computed from observed seismic noise records. Nearby borehole data provided both a guide for interpretation and a confirmation of the usefulness of the passive Rayleigh-wave microtremor method. Sensitivity analyses of resolvable modelling parameters demonstrate that estimates of shear velocities and layer thicknesses are accurate to within approximately $10\%\;to\;20\%$ using the spatial autocorrelation (SPAC) technique. Improved accuracy can be obtained by constraining shear velocities and/or layer thicknesses using independent site knowledge. Although there exists potential for ambiguity due to velocity-thickness equivalence, the microtremor method has significant potential as a site investigation tool in situations where the use of traditional seismic methods is limited.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.2 no.4
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• pp.253-262
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• 2004

Construction of tunnels in a deep crystalline host rock for a potential High-Level Radioactive Waste(HLW) repository inevitably generates an excavation disturbed zone (EDZ). There have been a series of debates on whether a permeability in an EDZ increases or not and what would be the maximum depth of an EDZ. Recent studies show mixed opinions on permeability. However, there has been an international consensus on the thickness of an EDZ; 30 cm for TBM and 1 meter for controlled blast. One of the impacts of an EDZ is on determining the distance between adjacent deposition holes. The void gap by the excavation hinders relaxation of temperature profiles so that the current Korean reference designing distance between holes should be stretched out more to keep the maximum temperature in a buffer region below 100 degrees Celsius. The other impact of an EDZ is on the long-term post closure radiological safety. To estimate the impact, the reference scenario, the well scenario, is chosen. Released nuclides diffuse through a bentonite buffer region experiencing strong sorption and reach a fracture surrounded by a porous medium. Inside a fractured porous region, radionuclides migrate by advection and dispersion with matrix diffusion into a porous medium. Finally, they reach a well assumed to be a source of potable water for local residents. The annual individual dose is assessed on this well scenario to find out the significance of an EDZ. A profound sensitivity study was performed, but all results show that the impact is negligible. Even though the role of an EDZ turns out to be limited on overall safety assessment, still it is worthwhile to study the chemical role of an EDZ, such as a potential source for natural colloids, potential sealing of an open fracture by fine clay particles generated by the process of an EDZ, and alteration of a sorption mechanism by an EDZ in the future.

• BMB Reports
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• v.51 no.1
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• pp.14-20
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• 2018

Biomedical research involving nanoparticles has produced useful products with medical applications. However, the potential toxicity of nanoparticles in biofluids, cells, tissues, and organisms is a major challenge. The '-omics' analyses provide molecular profiles of multifactorial biological systems instead of focusing on a single molecule. The 'omics' approaches are necessary to evaluate nanotoxicity because classical methods for the detection of nanotoxicity have limited ability in detecting miniscule variations within a cell and do not accurately reflect the actual levels of nanotoxicity. In addition, the 'omics' approaches allow analyses of in-depth changes and compensate for the differences associated with high-throughput technologies between actual nanotoxicity and results from traditional cytotoxic evaluations. However, compared with a single omics approach, integrated omics provides precise and sensitive information by integrating complex biological conditions. Thus, these technologies contribute to extended safety evaluations of nanotoxicity and allow the accurate diagnoses of diseases far earlier than was once possible in the nanotechnology era. Here, we review a novel approach for evaluating nanotoxicity by integrating metabolomics with metabolomic profiling and transcriptomics, which is termed "metabotranscriptomics."

• YAKHAK HOEJI
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• v.41 no.6
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• pp.817-828
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• 1997

In order to investigate pharmacological properties of New Woohwangchungsimwon Pill (NWCH) and Woohwangchungsimwon Pill(WCH), effects of NWCH and WCH on cerebral ischemia and central nervous system were compared. Cerebral ischemia insult was performed using unilateral carotid artery occlusion in Mongolian gerbils. The histological observations showed preventive effect of NWCH and WCH treatments with ischemia-induced brain damage. The ATP in brain tissue was decreased in vehicle-treated ischemic gerbils. This decrease was prevented by NWCH and WCH treatment. In contrast to what was seen with ATP, the lactate and lipid peroxide were both elevated in vehicle-treated ischemic gerbils. This elevation was inhibited by NWCH and WCH treatments. In central nervous system, NWCH and WCH had sedative effect in rotarod and spontaneous activity test, but no effects on the hexobarbital-induced sleeping time. And, NWCH and WCH had weak anticonvulsion effects in electric shock- and pentetrazol-induced convulsion test. NWCH and WCH increased the respiration rate, but decreased the respiration depth in rats. Furthermore, NWCH and WCH showed antistress effect. Our findings suggest that the pharmacological profiles of NWCH on cerebral ischemia and central nervous system are similar to that of WCH.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.14 no.2
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• pp.151-160
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• 2002

A modeling system for three-dimensional flow (FEMOS) has been developed and applied to simulate the tidal currents of Asan Bay. The system can consider tidal flats changing with time and uses a finite element method that can adapt coastline change effectively. The simulation results for Asan Bay with large tidal flats, shallow water depth and high tidal range showed good agreements with the observed currents of long-term variations at the medium layer and short-term variations of vertical profiles. Based on the simulated tidal currents, the horizontal distributions of bottom shear stress were calculated and showed close relation with the change of bottom topography. The system can be used widely to study coastal circulation in the coastal region with complex geography.

• Journal of Radiation Protection and Research
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• v.43 no.1
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• pp.10-19
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• 2018

Background: Monte Carlo (MC) simulation is the most accurate for calculating radiation dose distribution and determining patient dose. In MC simulations of the therapeutic accelerator, the characteristics of the initial electron must be precisely determined in order to achieve accurate simulations. However, It has been computation-, labor-, and time-intensive to predict the beam characteristics through predominantly empirical approach. The aim of this study was to analyze the relationships between electron beam parameters and dose distribution, with the goal of simplifying the MC commissioning process. Materials and Methods: The Varian Clinac 2300 IX machine was modeled with the Geant4 MC-toolkit. The percent depth dose (PDD) and lateral beam profiles were assessed according to initial electron beam parameters of mean energy, radial intensity distribution, and energy distribution. Results and Discussion: The PDD values increased on average by 4.36% when the mean energy increased from 5.6 MeV to 6.4 MeV. The PDD was also increased by 2.77% when the energy spread increased from 0 MeV to 1.019 MeV. In the lateral dose profile, increasing the beam radial width from 0 mm to 4 mm at the full width at half maximum resulted in a dose decrease of 8.42% on the average. The profile also decreased by 4.81% when the mean energy was increased from 5.6 MeV to 6.4 MeV. Of all tested parameters, electron mean energy had the greatest influence on dose distribution. The PDD and profile were calculated using parameters optimized and compared with the golden beam data. The maximum dose difference was assessed as less than 2%. Conclusion: The relationship between the initial electron and treatment beam quality investigated in this study can be used in Monte Carlo commissioning of medical linear accelerator model.