• Journal of the Korean Institute of Telematics and Electronics A
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• v.30A no.8
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• pp.42-48
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• 1993

Ar ions were implanted at 1 MeV into (100)Cz Si wafers with dose of 1 * 10$^{15}$ ions/cm$^{2}$. Damage induced by high energy implantation and its annealing behavior during rapid thermal annealing for 10sec at temperatures from 550 to 1100${\circ}C$ were investigated by crosssection transmission electron microscopy study. It can be clearly seen from the observation that the SPE(Solid Phase Epitaxy) regrowth of the buried amorphous layer induced by ion implantation proceeds from both upper and lower amorphous/crystalline (a/c) interfaces, and the activation energy for SPE from interfaces were both 1.43eV. Misfit dislocation where two interfaces met was formed and it coalesced into the hair pin dislocation in the upper regrown region. At the higher temperature after annealing out of the misfit dislocation, hair pin dislocations showed considerable drop in its bandwidth. However, they were not disappeared even at the temperature 1100${\circ}C$ with the end of range dislocation loops which were formed at the original lower a/c interface.

• Journal of Radiation Protection and Research
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• v.29 no.1
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• pp.41-48
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• 2004

A safety assessment code, called SAGE (Safety Assessment Groundwater Evaluation), has been developed to describe post-closure radionuclide releases and potential radiological doses for low- and intermediate-level radioactive waste (LILW) disposal in an engineered vault facility in Korea. The conceptual model implemented in the code is focused on the release of radionuclide from a gradually degrading engineered barrier system to an underlying unsaturated zone, thence to a saturated groundwater zone. The radionuclide transport equations are solved by spatially discretizing the disposal system into a series of compartments. Mass transfer between compartments is by diffusion/dispersion and advection. In all compartments, radionuclides ate decayed either as a single-member chain or as multi-member chains. The biosphere is represented as a set of steady-state, radionuclide-specific pathway dose conversion factors that are multiplied by the appropriate release rate from the far field for each pathway. The code has the capability to treat input parameters either deterministically or probabilistically. Parameter input is achieved through a user-friendly Graphical User Interface. An application is presented, which is compared against safety assessment results from the other computer codes, to benchmark the reliability of system-level conceptual modeling of the code.

• JSTS:Journal of Semiconductor Technology and Science
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• v.5 no.3
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• pp.173-181
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• 2005

A new two dimensional (2-D) model for the potential distribution of fully depleted short-channel ion-implanted silicon MESFET's has been presented in this paper. The solution of the 2-D Poisson's equation has been considered as the superposition of the solutions of 1-D Poisson's equation in the lateral direction and the 2-D homogeneous Laplace equation with suitable boundary conditions. The minimum bottom potential at the interface of the depletion region due to the metal-semiconductor junction at the Schottky gate and depletion region due to the substrate-channel junction has been used to investigate the drain-induced barrier lowering (DIBL) and its effects on the threshold voltage of the device. Numerical results have been presented for the potential distribution and threshold voltage for different parameters such as the channel length, drain-source voltage, and implanted-dose and silicon film thickness.

• The KSFM Journal of Fluid Machinery
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• v.18 no.2
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• pp.54-59
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• 2015

The performance of UV reactor which is used in water treatment is strongly affected by UV fluence rate and water flow in the UV reactor. Therefore, CFD tools are widely used in designing process of UV reactors. This paper describes the development of a computational fluid dynamics (CFD) methodology that can be used to calculate the performance of open channel type UV reactor used in wastewater treatment plant. All computations were performed using commercial CFD code, CFX, by considering three dimensional, steady, incompressible flow. The Eulerian-Eulerian multi-phase method were used to capture the water-air interface. The MSSS model, provided by UVCalc3D, was used to calculate the UV intensity field. The numerical predictions and calculated UV Dose were compared with experimental dataset to validate the CFD methodology. The reactor performance based on MS2 log reduction was well matched with measurements within 6%.

• Journal of Korean Society of Water and Wastewater
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• v.10 no.2
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• pp.55-69
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• 1996

Backwashing is one of the most important processes in water treatment. Several models have been utilized to predict minimum fluidization velocity and expansion of media. However, it is not unusual that the actual bahavior of media dose not agree well with the prediction. This study has investigated the applicability of models in predicting the minimum fluidization velocity of sand media. However even the better model has predicted minimum fluidization velocity 1.1 to 1.8 times higher than actual fluidization velocity. The expansion rate of sand media was inspected. It is found that the actual expansion rate was greater than the predicted. In this study condition, use of $d_{10}$ instead of $d_{60}$ was better to predict the expansion of media. On the contrary to the sand media, the actual expansion of anthracite media was less than that predicted. Sometimes it is reported that the dual media has been overflown during backwashing and mixed severely at the interface. It is because the grain size distribution of anthracite has not been selected properly. The numerical values for media expansion found in this study could be referred as the useful data in operating and/or designing filter media.

• The Korean Journal of Physiology and Pharmacology
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• v.8 no.2
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• pp.83-88
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• 2004

The purpose of this study was to provide a basis for studying the molecular mechanism of pharmacological action of chlorhexidine digluconate. Large unilamellar vesicles (OPGTL) were prepared with total lipids extracted from cultured Porphyromonas gingivalis outer membranes (OPG). The anthroyloxy probes were located at a graded series of depths inside a membrane, depending on its substitution position (n) in the aliphatic chain. Fluorescence polarization of n-(9-anthroyloxy)stearic acid was used to examine effects of chlorhexidine digluconate on differential rotational mobility, while changing the probes' substitution position (n) in the membrane phospholipids aliphatic chain. Magnitude of the rotational mobility of the intact six membrane components differed depending on the substitution position in the descending order of 16-(9-anthroyloxy)palmitic acid (16-AP), 12, 9, 6, 3 and 2-(9-anthroyloxy)stearic acid (12-AS, 9-AS, 6-AS, 3-AS and 2-AS). Chlorhexidine digluconate increased in a dose-dependent manner the rate of rotational mobility of hydrocarbon interior of the OPGTL prepared with total lipids extracted from cultured OPG, but decreased the mobility of membrane interface of the OPGTL. Disordering or ordering effects of chlorhexidine digluconate on membrane lipids may be responsible for some, but not all of its bacteriostatic and bactericidal actions.

• The Journal of Korean Academy of Prosthodontics
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• v.29 no.2
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• pp.245-265
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• 1991

The purpose of this study was to observe the changes of the elemental transmission and bond strength between the metal and porcelain according to various kinds of ion beam mixing method. ion beam mixing of $meta1/SiO_2$ (silica), $meta1/Al_2O_3$(alumina) interfaces causes reactions when the $Ar^+$ was implanted into bilayer thin films using a 100KeV accelerator which was designed and constructed for this study. A vacuum evaporator used in the $10^{-5}-10^{-6}$ Torr vacuum states for the evaporation. For this study, three kinds of porcelain metal selected, -precious, semiprecious, and non-precious. Silica and alumina were deposited to the metal by the vacuum evaporator, separately. One group was treated by two kinds of dose of the ion beam mixing $(1\times10^{16}ions/cm^2,\;5\times10^{15}ions/cm^2)$, and the other group was not mixed, and analyzed the effects of ion beam mixing. The analyses of bond strength, elemental transmissions were performed by the electron spectroscopy of chemical analysis (ESCA), light and scanning electron microscope, scratch test, and micro Vickers hardness tests. The finding led to the following conclusions. 1. In the scanning electron and light microscopic views, ion beam mixed specimens showed the ion beam mixed indentation. 2. In the micro Vickers hardness and scratch tests, ion beam mixed specimens showed higher strength than that of non mixed specimens, however, nonprecious metal showed a little change in the bond strength between mixed and non mixed specimens. 3. In the scratch test, ion beam mixed specimens showed higher shear strength than that of non treated specimens at the precious and semiprecious groups. 4. In the ESCA analysis, Au-O and Au-Si compounds were formed and transmission of the Au peak was found ion beam mixed $SiO_2/Au$ specimen, simultaneously, in the higher and lower bonded areas, and ion beam mixed $SiO_2/Ni-Cr$ specimen, oxygen, that was transmitted from $SiO_2\;to\;SiO_2/Ni-Cr$ interface combined with 12% of Ni at the interface.

• Journal of Adhesion and Interface
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• v.19 no.2
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• pp.74-82
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• 2018

Many methods for cross-linking acrylic PSAs have been discussed previously. For high cross-linking density, epoxy functionalized monomer and methyl aziridines as cross-linking agents were used in this study. Additionally, photopolymerization using different UV doses was investigated to synthesize a binder because of its rapid productivity. FT-IR analysis, curing behaviours and adhesion performance were examined for the relationship between UV doses and temperature as curing conditions. According to the results, the gel fraction was over 50% even at $120^{\circ}C$ after UV curing at a dose of $800mJ/cm^2$. On the other hand, while gel fractions of all samples reached approximately 80% only at $180^{\circ}C$ in thermal curing for 1 hour, gel fractions of the samples after thermal curing for 3 hours increased rapidly above $120^{\circ}C$ regardless of UV doses and reached approximately 100% at $180^{\circ}C$. This means that the second cross-linking reaction, esterification, is mainly dependent on the curing temperature.

• Journal of the Korean Society of Radiology
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• v.4 no.2
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• pp.21-25
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• 2010

Recently, various semiconductor compounds as radiation detection material have been researched for a diagnostic x-ray detector application. In this paper, we have fabricated the CdS detecton sensor that has good photosensitivity and high x-ray absorption efficiency among other semiconductor compounds, and evaluated the application feasibility by investigating the detection properties about energy range of diagnostic x-ray generator. We have fabricated the line voltage selector(LCV) for a signal acquisition and quantities of CdS sensor, and designed the voltage detection circuit and rectifying circuit. Also, we have used a relative relation algorithm according to x-ray exposure condition, and fabricated the interface board with DAC controller. Performance evaluation was investigated by data processing using ANOVA program from voltage profile characteristics according to resistive change obtained by a tube voltage, tube current, and exposure time that is a exposure condition of x-ray generator. From experimental results, an error rates were reduced according to increasing of a tube voltage and tube current, and a good properties of 6%(at 90 kVp) and 0.4%(at 320 mA) ere showed. and coefficient of determination was 0.98 with relative relation of 1:1. The error rate according to x-ray exposure time showed exponential reduction because of delayed response velocity of CdS material, and the error rate has 2.3% at 320 msec. Finally, the error rate according to x-ray dose is below 10%, and a high relative relation was showed with coefficient of determination of 0.9898.

• Journal of the Korean Society of Radiology
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• v.14 no.5
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• pp.529-535
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• 2020

Geant4 is compatible with the Windows operating system in C++ language use, enabling interface functions that link DICOM or software. It was simulated to address the basic structure of the simulation using Geant4/Gate code and to specifically verify the density composition and lung cancer process in the human phantom. It was visualized using the Gate Graphic System, i.e. openGL, Ray Tracer: Ray Tracing by Geant4 Tracing, and using Geant4/Gate code, lung cancer is modeled in the human phantom area in 3D, 4D to verify the simulation progress. Therefore, as a large number of new functions are added to the Gate Code, it is easy to implement accurate human structure and moving organs.