• Proceedings of the KOSOMBE Conference
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• v.1998 no.11
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• pp.319-320
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• 1998

We have developed algorithm for calculating tumor dose from transmission dose in radiation therapy. Using data acquisition card and LabVIEW programming language, we acquired the signal from 9 ion chambers, processed and displayed it in real time. And we also developed GUI(Graphic User Interface) for system operation.

• Transactions on Electrical and Electronic Materials
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• v.6 no.1
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• pp.1-5
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• 2005

Continued scaling of MOS devices requires the formation of the ultra shallow and very heavily doped junction. The simulation and experiment results show that the degradation of pMOS performance in logic and SRAM pMOS devices due to the excessive diffusion of the tail and a large amount of dose loss in the extension region. This problem comes from the high-temperature long-time deposition process for forming the spacer and the presence of fluorine which diffuses quickly to the $Si/SiO_{2}$ interface with boron pairing. We have studied the method to improve the pMOS performance that includes the low-energy boron implantation, spike annealing and device structure design using TCAD simulation.

• JSTS:Journal of Semiconductor Technology and Science
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• v.4 no.2
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• pp.124-127
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• 2004

W/n-GaN Schottky diodes were irradiated with $^{60}Co\;{\gamma}-rays$ to doses up to 315Mrad. The barrier height obtained from current-voltage (I-V) measurements showed minimal change from its estimated initial value of ${\sim}0.4eV$ over this dose range, though both forward and reverse I-V characteristics show evidence of defect center introduction at doses as low as 150 Mrad. Post irradiation annealing at $500^{\circ}C$ increased the reverse leakage current, suggesting migration and complexing of defects. The W/GaN interface is stable to high dose of ${\gamma}-rays$, but Au/Ti overlayers employed for reducing contact sheet resistance suffer from adhesion problems at the highest doses.

• Journal of radiological science and technology
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• v.45 no.6
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• pp.553-560
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• 2022

The purpose of this study is to evaluate the clinical risk according to the applicator heterogeneity, mislocation, and tissue heterogeneity correction through a dose verification program during brachytherapy of cervical cancer. We performed image processing with MATLAB on images acquired with CT simulator. The source was modeled and stochiometric calibration and Monte-Carlo algorithm were applied based on dwell time and location to calculate the dose, and the secondary cancer risk was evaluated in the dose verification program. The result calculated by correcting for applicator and tissue heterogeneity showed a maximum dose of about 25% higher. In the bladder, the difference in excess absolute risk according to the heterogeneity correction was not significant. In the rectum, the difference in excess absolute risk was lower than that calculated by correcting applicator and tissue heterogeneity compared to the water-based calculation. In the femur, the water-based calculation result was the lowest, and the result calculated by correcting the applicator and tissue heterogeneity was 10% higher. A maximum of 14% dose difference occurred when the applicator mislocation was 20 mm in the Z-axis. In a future study, it is expected that a system that can independently verify the treatment plan can be developed by automating the interface between the treatment planning system and the dose verification program.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 2004.11a
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• pp.133-138
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• 2004

Proton exchange membrane fuel cell (PEMFC) is considered as a clean and efficient energy conversion det ice for mobile and stationary applications. Anions all the components of the PEMFC, the interface between the electrolyte ,and electrode catalyst plays an important role in determining tile cell performance since the electrochemical reactions take place at the interface in contact with tile reactant gases. Therefore, to increase the interface area and obtain a high-performance PEMFC, surface of the electrolyte membrane was roughened by Ar$^{+}$ beam bombardment. The results imply that by modifying surface of the electrolyte membrane, platinum loading can be reduced significantly without performance loss. To optimize the surface treatment condition, effects of ion dose density on characteristics of the membrane/electrode interface were examined by measuring the cell performance, impedance spectroscopy, and cyclic voltammograms. Surface of the modified membranes were characterized using scanning electron microscopy and FT-IR.R.

• Journal of Adhesion and Interface
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• v.18 no.3
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• pp.134-140
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• 2017

In this study, we made UV cured acrylic pressure sensitive adhesive containing silicone-urethane-acrylate (SUA) oligomer for a coating on protective film and investigated the effect of SUA oligomer content and UV-dose on adhesion properties. The results illustrated that peel strength decreases with increasing oligomer content and UV-dose, while holding power increases. The gel fractions sharply increased after UV irradiation and then remain constant with prolonged UV exposure. From peel-off test, sample S70 (70% oligomer content) shows the best peelability and removability without remaining any mark or adhesive material on the test substrate than S50 (50% oligomer content) and S60 (60% oligomer content). Sample S70 also showed a surface energy lower than $26mJ/m^2$ and a transmittance higher than 95% at UV-dose 1857 and $2270mJ/cm^2$ which met the required properties for protective film application.

• The Journal of Korean Society for Radiation Therapy
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• v.8 no.1
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• pp.75-81
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• 1996

When high energy photon beam is incident upon an air cavity interface the effect of ionization build-up observed . This phenomenon is resulting from the surface layers of the lesions are significant deficiency of electrons reaching the layers because of the replacement, of solid scattering material by the air cavity, that is lack of electronic equilibrium. Measurement have been made in an acrylic phantom with a parallel plate chamber and high energy photon beams, CO-60, 4MV, 6MV and 10MV X-rays have been investigated. The result of our study show that a significant effect was measured and was determined to be very dependent on field size, air cavity dimension and photon energy. The reductions were much larger for 10MV beam, underdosage at the interface was 12, 12.2, 16.9 and $20.6\%$ for the CO-60, 4MV, 6MV and 10MV, respectively. It was found that this non-equilibrium effect at the interface is more severe for the higher energy beams than that of lower energy beams and the larger cavity dimensions the larger beam reductions occur. This problem is of clinical concern when lesions such as carcinoma beyond air cavities are irradiated, such as larynx, glottic and the patients with maxillectomy and ethmoidectomy and so forth.

• Korean Journal of Materials Research
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• v.13 no.1
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• pp.43-47
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• 2003

As and BF$_2$dopants are implanted for the formation of source/drain with dose of 1${\times}$10$^{15}$ ions/$\textrm{cm}^2$∼5${\times}$10$^{15}$ ions/$\textrm{cm}^2$ then formed cobalt disilicide with Co/Ti deposition and doubly rapid thermal annealing. Appropriate ion implantation and cobalt salicide process are employed to meet the sub-0.13 $\mu\textrm{m}$ CMOS devices. We investigated the process results of sheet resistance, dopant redistribution, and surface-interface microstructure with a four-point probe, a secondary ion mass spectroscope(SIMS), a scanning probe microscope (SPM), and a cross sectional transmission electron microscope(TEM), respectively. Sheet resistance increased to 8%∼12% as dose increased in $CoSi_2$$n^{＋}$ and $CoSi_2$$p^{V}$ , while sheet resistance uniformity showed very little variation. SIMS depth profiling revealed that the diffusion of As and B was enhanced as dose increased in $CoSi_2$$n^{＋}$ and $CoSi_2$$p^{＋}$ . The surface roughness of root mean square(RMS) values measured by a SPM decreased as dose increased in $CoSi_2$$n^{＋}$ , while little variation was observed in $CoSi_2$$p^{＋}$ . Cross sectional TEM images showed that the spikes of 30 nm∼50 nm-depth were formed at the interfaces of $CoSi_2$$n^{＋}$ / and $CoSi_2$/$p^{＋}$, which indicate the possible leakage current source. Our result implied that Co/Ti cobalt salicide was compatible with high dose sub-0.13$\mu\textrm{m}$ process.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2002.09a
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• pp.65-67
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• 2002

A PC based software, the RTP Research Tool Box (RTB), was developed for IMRT optimization research. The software was consisted of an image module, a beam registration module, a dose calculation module, a dose optimization module and a dose display module. The modules and the Graphical User Interface (GUI) were designed to easily amendable by negotiating the speed of performing tasks. Each module can be easily replaced to new functions for research purpose. IDL 5.5 (RSI, USA) language was used for this software. Five major modules enable one to perform the research on the dose calculation, on the dose optimization and on the objective function. The comparison of three cost functions, such as the uncomplicated tumor control probability (UTCP), the physical objective function and the pseudo-biological objective function, which was designed in this study, were performed with the RTB. The optimizations were compared to the simulated annealing and the gradient search optimization technique for all of the optimization objective functions. No significant differences were found among the objective functions with the dose gradient search technique. But the DVH analysis showed that the pseudo-biological objective function is superior to the physical objective function when with the simulated annealing for the optimization.

• Journal of radiological science and technology
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• v.33 no.3
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• pp.261-268
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• 2010

This study is compared that the dose distribution by experimentation and radiation therapy planning (RTP) when the air cavity region was treated high energy photon. The dose measurements were performed with a 6 MV photon beam of linear accelerator. The polystyrene and self made acyl phantom were similar to tissue density of the human body. A parallel plate chamber was connected to an electrometer. The measurement setup was SCD (Source Chamber Distance) 100 cm and the distance of surface from air cavity was 3 cm. Absorbed dose of interface were measured by area and height. The percent depth dose were measured presence and absence of air cavity, depth according to a ratio of field size and air cavity size. The dose distribution on planning was expressed to do the inhomogeneity correction. As the area of air cavity was increased, the absorbed dose were gradually reduced. It was slightly increased, when the height of air cavity was changed from 0 cm to 0.5 cm. After the point, dose was decreased. In case of presence of air cavity, dose after distal air cavity interface was more great than absence of air cavity. The rebuild up by field size and area of air cavity occurred for field size, $4{\times}4\;cm^2$, $5{\times}5\;cm^2$ and $6{\times}6\;cm^2$, with fixed on area of air cavity, $5{\times}5\;cm^2$. But it didn't occur at $10{\times}10\;cm^2$ field size. On the contrary, the field size was fixed on $5{\times}5\;cm^2$, rebuild up occurred in area of air cavity, $4{\times}4\;cm^2$, $5{\times}5\;cm^2$. but, it did not occur for air cavity, $2{\times}2\;cm^2$, $3{\times}3\;cm^2$. All of the radiation therapy planning were not occurred rebuild up. It was required to pay attention to treat tumor in air cavity because the dose distribution of planning was different from the dose distribution of patient.