• The Journal of Korean Society for Radiation Therapy
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• v.1 no.1
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• pp.37-42
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• 1985

Radiation Therapy(RT) has been used in the treatment of breast cancer for over 80 years. Technically, it should include a part or all of such areas as chest wall or breast, axilla, internal mammary nodes(IM) and supraclavicular nodes (SCL). Authors tried three-field technique for the treatment of breast cancer using 6 MV linear accelerator, exclusively the department of Radiology, Kang-Nam St. Mary's Hospital, at Catholic Medical College. The field junction was checked by a phantom study and radiation doses measured by film densitometry and TLD. The 3 fields we used in this study were two isocentric opposing tangential fields encompassing the breast, chest wall and occasionally IM and one single anterior field encompassing the axilla and SCL. Using appropriate beam blocks and blouses, we were able to avoid unwanted intrinsic divergency of photon beam. Blocking also enabled us to set-up precise radiation field with ease.

• Journal of Radiation Protection and Research
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• v.13 no.1
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• pp.21-30
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• 1988

The 6 MV photon beam of a linear accelerator (Mevatron 67) was studied for electron contamination. The surface dose, attributable almost entirely to contamination electrons, has a linear dependence on field width for square fields and an inverse square dependence on distance from the bottom of the fixed head assembly. Build-up and surface dose measurements were taken with and without an acrylic blocking tray in place. Further measurements were made with a copper filter designed to reduce secondary electrons emitted by photon interactions with the acrylic tray. The results are discussed in relation to skin sparing effect for radiation therapy patients. To achieve the maximum skin sparing effect, the selection of the optimum SSD and TSD is needed.

• Radiation Oncology Journal
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• v.2 no.2
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• pp.303-309
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• 1984

Radiation therapy(RT) has been used in the treatment of breast cancer for over 80years. Technically, it should include a part or all of such areas as chest wall or breast, axilla, internal mammary nodes (IM) and supraclavicular nodes (SCL). Authors tried three-field technique for the treatment of breast cancer using 6-MV linear accelerator, exclusively the department of radiology. Kang-Nam St. Mary's Hospital, at Catholic Medical College. The field junction was checked by a Phantom study and radiation doses measured by film densitometry and TLD. The 3 fields we used in this study were two isocentric opposing tangential fields encompassing the breast, chest wall and occasionally IM and one single anterior field encompassing the axilla and SCL. sing appropriate beam blocks and boluses, we were able to avoid unwanted intrinsic divergency of photon beam. Blocking also enabled us to set-up precise radiation field with ease.

• Journal of Korea Multimedia Society
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• v.20 no.2
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• pp.153-162
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• 2017

Today, weather radar is used as a key tool for modern high-tech weather observations and forecasts, along with a wide variety of ground gauges and weather satellites. In this paper, we propose a frequency transform based weather radar image processing technique to improve the weather radar image damaged by beam blocking and clutter removal in order to minimize the uncertainty of the weather radar observation. In the proposed method, DCT based mean energy correction is performed to improve damage caused by beam shielding, and DWT based morphological image processing and high frequency cancellation are performed to improve damage caused by clutter removal. Experimental results show that the application of the proposed method to the damaged original weather radar image improves the quality of weather radar image adaptively to the weather echo feature around the damaged area. In addition, radar QPE calculated from the improved weather radar image was also qualitatively confirmed to be improved by the damage. In the future, we will develop quantitative evaluation scales through continuous research and develop an improved algorithm of the proposed method through numerical comparison.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.30 no.10 s.253
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• pp.1314-1319
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• 2006

This paper describes the novel fabrication method of the high-aspect-ratio nano structure which is impossible by conventional method using a shadow mask and a Deep X-ray Lithography (DXRL). The shadow mask with $1{\mu}m-sized$ apertures is fabricated on the silicon membrane using a conventional UV-lithography. The size of aperture is reduced to 200nm by accumulated low stress silicon nitride using a LPCVD (low pressure chemical vapor deposition) process. The X-ray mask is fabricated by depositing absorber layer (Au, $3{\mu}m$) on the back side of nano shadow mask. The thickness of an absorber layer must deposit dozens micrometers to obtain contrast more than 100 for a conventional DXRL process. The thickness of $3{\mu}m-absorber$ layer can get sufficient contrast using a central beam stop method, blocking high energy X-rays. The nano circle and nano line, 200nm in diameter in width, respectively, were demonstrated 700nm in height with a negative photoresist of SU-8.

• The Korean Journal of Pharmacology
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• v.8 no.2
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• pp.35-39
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• 1972

Previous studies on the effect of the visible lights on the organism have shown the possible influences on the nervous system. It was reported that the illumination of blue beam increased the sympathetic tone and that of red beam increased the parasympathetic tone. The pharmacological actions of the sympathomimetics were also known to be altered by various visible lights. But their modes and mechanisms of actions on the nervous system have not been clarified and is obscure. To elucidate the precise mechanism of action of the visible lights on the nervous system, present study was made to observe the survival time of the mole living in the dark environment, under the illumination of the various visible lights and influences of several drugs. The results are summerized as follows: 1. The illumination of the natural sun light caused the survival time of the mole to be shortened and visible monochromatic beams (red, blue and green) even more markedly shortened the survival time. No significant difference was noted depending on the wave length of the chromatic beam. 2. The shortened survival time caused by the visible monochromatic lights was prolonged by strychnine but not affected by morphine. 3. The survival time under the illumination of the visible monochromatic lights was prolonged by acetylcholine and physostigmine. 4. The shortened survival time under the illumination of the monochromatic visible lights was not affected by adrenaline but prolonged by priscoline. It is suggested that the shortened survival time of the mole by the illumination of the visible lights can be prolonged by the stimulation of central and parasympathetic nervous system and blocking of the sympathetic nervous system.

• Polymer(Korea)
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• v.26 no.2
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• pp.160-167
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• 2002

We synthesized HPP-g-GMA copolymer using pre-irradiation method by E-beam and aminated HPP-g-GMA using amination reaction. Degree of grafting increased with increasing GMA monomer concentration and showed the maximum value of 130% at 1.46 M of GMA. The degree of amination increased with increasing the degree of grafting. When the degree of grafting was 100%, degree of amination showed the maximum value of 37.4%. The ion exchange capacity of aminated HPP-g-GMA was about 3.78 meq/g, and it showed remarkable adsorption ability of hollow fiber ion exchanger. Through the BET analysis, the surface area of aminated HPP-g-GMA was 54.83 $\m^2/g$ and the mean pore size was $26\AA$. These showed the decrease of surface area and the slight increase of the mean pore size. SEM results show that the thickness of fiber increased after the step of reaction and there pore blocking phenomena was not observed. The aminated HPP-g-GMA was synthesized successfully and found to be suitable for the adsorption and separation of anion.

• Journal of the Semiconductor & Display Technology
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• v.5 no.2 s.15
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• pp.1-5
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• 2006

The GaN thin film on the 8 periods InGaN/GaN multi-quantum well structure was grown on the sapphire substrate using metal-organic chemical vapor deposition. The nano-scaled triangular-lattice holes with the diameter of 150 nm were patterned on a polymethylmethacrylate blocking film using an electron beam nano-lithography system. The thin slab and two-dimensional photonic crystals with the thickness of 28 nm were fabricated on the GaN layer for the blue light diffraction sources. The photonic crystal with the lattice parameter of 460 nm enhances spectral intensity of photoluminescence indicating that the photonic crystals provides the source of nano-diffraction for the blue light of the 450-nm wavelength.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2015.11a
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• pp.306-307
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• 2015

유기태양전지의 대표적 Hole Transporting Layer(HTL)로는 전도성 고분자인 PEDOT:PSS이다. PEDOT:PSS는 약산성의 물질로 전극을 부식시켜 디바이스의 효율을 감소시키기 때문에 PEDOT:PSS를 대체하기 위한 Buffer층에 대한 연구가 활발히 진행되어지고 있다. PEDOT:PSS를 대체할 수 있는 Nickel Oxide(NiO) Buffer 층은 wide band-gab으로 Hole Transporting Layer와 Electron Blocking Layer 역할을 동시에 하여 디바이스의 효율을 향상시킬 수 있으며, 디바이스의 수명을 향상시킬 수 있다는 장점이 있다. NiO는 용액공정과 Sputter 증착 방법으로 형성할 수 있는데, 용액공정은 고온공정이 요구되어지고 Sputter 증착방법은 산화되기 쉬운 전극위에서는 전극의 손상을 발생한다. 본 연구에서는 이러한 단점을 해결하기 위해서 Ni을 Magnetron Sputter로 증착한 후 Ion Beam 처리를 통해 산화시켜 NiO 층을 형성하는 방법을 연구하였다. 본 연구에서 제안한 NiO형성 방법으로 유기태양전지를 제작하여 PEDOT:PSS를 Buffer층으로 사용한 태양전지와 Voc가 0.72 V로 유사하게 나와 NiO가 Buffer층으로 잘 형성된 것을 확인하였다.

• Progress in Medical Physics
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• v.6 no.2
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• pp.41-50
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• 1995

The absorbed dose and contaminant electron distribution of therapeutic X-ray beam (15MV photon) was studied with a half blocked beams of 30$\times$30$\textrm{cm}^2$ and field size ranging from 5$\times$5 to 30$\times$30$\textrm{cm}^2$. For a 15MV photon beam energy, the value of the depth of dose maximum, d$_{max}$, gradually decrease with increasing field size from 5$\times$5 to 30$\times$30$\textrm{cm}^2$ due to mainly by contaminant electrons which are produced in the flattening filter and scattered by collimator jaws, tray holder〔Lucite〕, blocking block and air. The results suggest that separate dosimetry data should be kept for blocked and unblocked field. The inherence of the contaminant electrons to the open field depth of maximum dose can lead to mistaken results if attenuation measurements are made at that depth. A nurmerous contaminant electrons mainly were distributed as shape of corn in the central photon beam and their path length in the water were shorter than 30mm because of the electrons energy having around 6MeV. These results clearly appears that the substraction of scattered electrons (electrons and positrons) from the total depth dose curve not only lowers the absolute dose in the bulidup region and surface dose, it also causes a shift of d$_{max}$ to a deeper depth. In the terapeutic high energy photon beam, the absorbed dose near the buildup region is the combined result of incident contaminant electrons and phantom generated electronsrons.