• 한국진공학회지
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• 제8권4B호
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• pp.548-555
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• 1999

The NBI (Neutral BGeam Injection) System for the Korea Superconducting Tokamak Advanced Research (KSTAR) is composed of ion sources, neutralizers, bending magnets, ion dumps, and calorimeter. The vacuum chamber, in which all of the beam line components are enclosed, is composed of differential pumping system for the effective transfer of the neutral beams. The needed pumping speeds of each of the divided vacuum chamber and the optimized gas flow rate ot the neutralizer were calculated with the help of the particle balance equations. The minimum gas flow rate to the ion sources for producing needed beam current (120kV, 65A, 78MW), the pressure distributions in the vacuum chamber for minimizing re-ionization loss, and the beam loss rate on the beam line components were used as the input in the calculation. Also the scenario for short pulse operation was determined by analysing the time dependent equations. It showed that beam extraction during less than 0.5 sec could be made only with TMP.

• 대한기계학회논문집B
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• 제31권8호
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• pp.718-723
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• 2007

The new concept spark plug was developed to study its influence on the combustion characteristics of SI engine. It has pre-ignition chamber in the lower end of spark plug and flame hole, in which fresh mixture gas can be introduced without any fuel supply system. This spark plug was tested with a commercial SI engine. Fuel consumption rate, emission gas and MBT timing were measured in the engine dynamometer for various flame hole numbers, hole positions, hole sizes of the pre-ignition chamber of the spark plug. And average flame propagation speed was measured by using the head gasket ionization probe in single cylinder engine. The new concept spark plug induces fast bum in combustion compared with the conventional spark plug, and MBT(Minimum advance for Best Torque) timing was retarded about $3{\sim}5^{\circ}$ crank angle. The flame hole number, hole direction and volume of pre-ignition chamber were found to influence the combustion characteristics.

• Asian Pacific Journal of Cancer Prevention
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• 제13권3호
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• pp.985-989
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• 2012

Objective: To make sure the feasibility with $^{18F}FDG$ PET/CT to guided dynamic intensity-modulated radiation therapy (IMRT) for nasopharyngeal carcinoma patients, by dosimetric verification before treatment. Methods: Chose 11 patients in III~IVA nasopharyngeal carcinoma treated with functional image-guided IMRT and absolute and relative dosimetric verification by Varian 23EX LA, ionization chamber, 2DICA of I'mRT Matrixx and IBA detachable phantom. Drawing outline and making treatment plan were by different imaging techniques (CT and $^{18F}FDG$ PET/CT). The dose distributions of the various regional were realized by SMART. Results: The absolute mean errors of interest area were $2.39%{\pm}0.66$ using 0.6cc ice chamber. Results using DTA method, the average relative dose measurements within our protocol (3%, 3 mm) were 87.64% at 300 MU/min in all filed. Conclusions: Dosimetric verification before IMRT is obligatory and necessary. Ionization chamber and 2DICA of I'mRT Matrixx was the effective dosimetric verification tool for primary focal hyper metabolism in functional image-guided dynamic IMRT for nasopharyngeal carcinoma. Our preliminary evidence indicates that functional image-guided dynamic IMRT is feasible.

• 대한방사선기술학회지:방사선기술과학
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• 제32권2호
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• pp.205-212
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• 2009

반응보정인자(h)는 고체팬텀에서 전리함의 반응을 물에서의 값으로 변환하기 위한 인자이다. RW3 고체 팬텀의 경우에 고에너지 X-선에 대한 반응보정인자는 선질과 깊이에 의존하는 것으로 알려져 있으나 조사면 크기와 SSD(Source to surface distance), 그리고 전리함 종류에 따른 의존성은 알려진 바가 없다. 본 연구에서는 알려진 의존성을 고찰하고 알려지지 않은 인자들에 대한 의존성을 조사하였다. 본 측정에서는 파머형전리함(FC65G, IBA, Germany)과 소형전리함(CC13, IBA, Germany)이 사용되었으며 대상 선질은 6 MV와 15 MV X-선이었다. 측정 결과 반응보정인자는 6 MV의 경우에 깊이 5 cm와 10 cm에서 각각 h = 1.015, 1.021, 그리고 15 MV의 경우에 깊이 5와 10 cm에서 각각 h = 1.024, 1.029로 나타났다. 결론적으로 반응보정인자는 선질과 깊이에는 의존하였지만 조사면 크기와 SSD에 따른 변화는 적었다. 전리함에 있어서 대상의 두 전리함에 대해서는 차이가 없었으나 다른 종류의 전리함에 대해서 추가적 연구가 필요하다고 생각한다. 본 결과는 RW3에서 전리함을 이용한 측정시 측정값의 분석에 활용될 수 있다.

• 한국의학물리학회지:의학물리
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• 제26권3호
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• pp.178-184
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• 2015

마커스 전리함은 치료용 전자선의 흡수선량 측정에 널리 사용되는 소형 평행 평판형 전리함이다. 특히 TRS-398 프로토콜에서는 $R_{50}<4.0g/cm^2$ (약 10 MeV 이하)에서 평행 평판형 전리함의 사용을 권고하고 있다. 그러나 TRS-398 프로토콜에서 $R_{50}<2.0g/cm^2$ (약 4 MeV 이하)에 대한 선질보정인자($k_{Q,Q_0}$)가 없어 낮은 에너지에 대한 선량측정이 필요한 경우에 마커스 전리함을 사용할 수 없다. 본 연구에서는 몬테칼로 계산(DOSRZnrc/EGSnrc)과 선량학적 계산을 이용하여 전자선 선질 $R_{50}=1.0$, 1.4, 2.0, 2.5, 3.0, $5.0g/cm^2$에 대하여 마커스 전리함(PTW-M34045)에 대한 $k_{Q,Q_0}$를 결정하였다. 본 연구에서는 결정된 $k_{Q,Q_0}$에 대해 TRS-398 및 TG-51 프로토콜의 자료와 알려진 자료들을 이용하여 평가하였다.

• Radiation Oncology Journal
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• 제15권1호
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• pp.65-69
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• 1997

목적 : 전리함의 크기로 인한 공간 분해능의 문제로 나타나는 전리함 반응함수를 제거하여 실제 선량분포를 얻고자 하였다. 대상 및 방법 : 내경 5mm, 6.4mm 등 2개의 서로 다른 크기를 갖는 전리함들과 다이오드, 필름의 반응함수를 구하고, 동일한 방사선 조사면$(10\times20cm^2)$의 선량분포 프로파일을 측정하여, 각각 deconvolution 기법으로 보정한 후, 보절된 격과가 일치하는지 비교하였다. 결과 : 원통형 전리함의 반응함수와 선량분포를 측정하였고, 측정한 선량분포에서 반응 함수의 효과를 deconvolution방법으로 제거하여 실제 선량분포를 찾아내었다. 사용한 에너지는 최대 광자선 에너지 4MV, 6MV, 15MV였으며, 전 에너지 영역에 걸쳐 보정 된 결과가 일치하는 방향으로 변화하였으며, 분해능 증가 효과가 있었다. 결론 : deconvolution 방법으로 전리함 반응 함수의 효과를 제거했을 때, 여러 측정기를 이용하여 측정한 선량 프로파일의 결과가 일치하는 경향을 볼 수 있어서 deconvolution 방법을 통해 얻은 선량 프로파일을 임상적으로 응용할 수 있음을 알았다.

• IEIE Transactions on Smart Processing and Computing
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• 제4권5호
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• pp.297-304
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• 2015

A multilayer gaseous detector has been developed for fast dose-verification measurements of raster-scan-mode therapeutic beams in particle therapy. The detector, which was constructed with eight thin parallel-plate ionization chambers (PPICs) and polymethyl methacrylate (PMMA) absorber plates, is closely tissue-equivalent in a beam's eye view. The gas-electron signals, collected on the strips and pad arrays of each PPIC, were amplified and processed with a continuous charge.integration mode. The detector was tested with 190-MeV raster-scan-mode beams that were provided by the Proton Therapy Facility at Samsung Medical Center, Seoul, South Korea. The detector responses of the PPICs for a 190-MeV raster-scan-mode proton beam agreed well with the dose data, measured using a 2D ionization chamber array (Octavius model, PTW). Furthermore, in this study it was confirmed that the detector simultaneously tracked the doses induced at the PPICs by the fast-oscillating beam, with a scanning speed of 2 m s-1. Thus, it is anticipated that the present detector, composed of thin PPICs and operating in charge.integration mode, will allow medical scientists to perform reliable fast dose-verification measurements for typical dynamic mode therapeutic beams.

• 대한전기학회논문지
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• 제35권5호
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• pp.199-204
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• 1986

The breakdown phenomena of N2 gas by 13.56MHz electric field are very different from those under steady field. In this paper we analyzed the breakdown phenomena by using electron distribution function and diffusion equation. The second-order differential equation derived from the Boltzmann equation is solved for the electron distribution function. The ionization rate and diffusion coefficient are calculated using kinetic theory formulas. The breakdown condition is that the number of electrons produced by ionization equal the number diffusing to the walls of the discharge chamber. Theses theoretical breakdown electric fields are calculated by the computer and compared with the experimental values.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2009년도 제38회 동계학술대회 초록집
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• pp.435-435
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• 2010

A inclined slot-excited plasma source is newly designed and constructed for higher flux HNB(Hyperthermal Neutral Beam) generation. The present source is different from the vertical SLAN(SLot ANtenna) sources [1] in two aspects. One is that the slots are inclined, and the other is that the magnetic field is configured to a cusp type. These modifications are intended to make the source plasma operated in sub-milli-torr pressure regime and as thin as possible, both of which is to get higher HNB flux by decreasing the re-ionization rate of the reflected atoms from the neutralizer [2]. The plasma is generated in a quartz tube of internal diameter 170 mm enclosed in a aluminum application chamber of larger diameter 250 mm. The microwave power is fed to the plasma chamber by 8 inclined slots cut into the application chamber wall. The slots are coupled the chamber to a WR280 waveguide wound around it to form a ring resonator. In order to make two slots $\lambda_g/2$ apart in phase, the adjacent slots are rotated in opposite directions. The rotation angle of the slots are set to $60^{\circ}$ from the chamber axis. Between the quartz chamber and the aluminum cylindrical chamber 8 NdFeB magnets are equally spaced and fixed to form the cusp magnetic field confinement and ECR (Electron Cyclotron Resonance) field. In this presentation, the magnetic and electromagnetic simulations, and the measured plasma parameters are given for both the inclined and the vertical slot-excited plasma sources. We also discuss how the sources can be tailored to suit better-performing HNB sources.

• 한국의학물리학회지:의학물리
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• 제1권1호
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• pp.85-90
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• 1990

Berger formulation was used to calculate the dose distribution of $^{60}$ Co source in tissue. $^{60}$ Co source was supposed as point source. The effect of the stainless-steel around the source was considered and Taylor Approximation Method was used for calculating exposure build-up factor. Calculated depth dose data was compared with measured data which was measured by the ionization chamber.