• Title/Summary/Keyword: Cylindrical chamber

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The Study on the Use of a Cylindrical Ionization Chamber for the Calibration of a 6 MeV Electron Beam (6 MeV 전자 빔의 교정에 원통형 이온함의 사용에 관한 연구)

  • Kim, Seong-Hoon;Huh, Hyun-Do;Choi, Sang-Hyun;Choi, Jin-Ho;Kim, Hyeog-Ju;Lim, Chun-Il;Shin, Dong-Oh
    • Progress in Medical Physics
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    • v.20 no.4
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    • pp.317-323
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    • 2009
  • The standard dosimetry systems based on an absorbed dose to water recommend to use a planeparallel chamber for the calibration of such a low-megavoltage electron beam as a nominal energy of 6 MeV. For this energy ranges of an electron beam a cylindrical chamber should not be used for the routinely regular beam calibration, but the feasibility of the temporary use of a cylindrical chamber was studied to give temporary solutions for special situations users meet. The PTW30013 chambers and the electron beam quality of $R_{50}=2.25\;g/cm^2$ were selected for this study. 10 PTW30013 chambers, a cylindrical type of chamber, were calibrated in KFDA, the secondary standards dosimetry laboratories, and given the absorbed dose-to-water calibration factors, respectively. A "temporary" $k_{Q,Q_0}$ for each chamber were calculated using the absorbed dose determined by a cross-calibrated planeparallel chamber, with the result of an average 0.9352 for 10 chambers. This value for PTW30013 chamber was used to determine an absorbed dose to water at the reference depth. The absorbed doses determined by PTW30013 chambers were in an agreement within 2% with that by ROOS chamber. In a certain situation where a cylindrical chamber be used instead of a planeparellel chamber, the value of 0.9352 might be useful to determine an absorbed dose to water in the same beam quality of electron beam as this study.

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Large Eddy Simulation of turbulent flow around a bluff body inside a sudden expansion cylindrical chamber (급 확대부를 갖는 실린더 챔버 내부의 둔각물체 주위 유동에 관한 대 와동 모사)

  • 최창용;고상철
    • Journal of Advanced Marine Engineering and Technology
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    • v.28 no.1
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    • pp.98-108
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    • 2004
  • This study concerns a large eddy simulation (LES) of turbulent flow around a bluff body inside a sudden expansion cylindrical chamber, a configuration which resembles a premixed gas turbine combustor The simulation code is constructed by using the general coordinate system based on the physical contravariant velocity components. The Smagorinsky model is employed and the calculated Reynolds number is 5,000 based on the bulk velocity and the diameter of the inlet pipe. The combined grid technique and cylindrical grid are tested in the numerical simulation with complex geometry. The predicted turbulent statistics are evaluated by comparing with LDV measurement data. The numerical flow visualizations depict the behavior of turbulent mixing process behind the flame holder.

Development of a Garlic Peeling System Using High-Pressure Water Jets (II) - Garlic peeling by cylindrical chamber with drilled nozzles - (습식 마늘박피 시스템 개발 (II) - 다수의 노즐이 배열된 원통형 챔버를 이용한 박피 실험)

  • 양규원;배영환;백성기
    • Journal of Biosystems Engineering
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    • v.29 no.3
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    • pp.225-232
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    • 2004
  • A new type of garlic peeling chamber has been developed which separates and peels garlic cloves using high-Pressure water Jets. The cylindrically-shaped chamber was fabricated with stainless steel plate and has a number of drilled holes, which function as solid-stream spray nozzles, on its interior wall. The chamber was divided into upper and lower section so that water can be applied at different pressures from each section. Three chambers of similar design were tested to evaluate their performances according to various pressure levels. The strongest correlation was observed between the pressure difference(lower-upper) and the proportion of unseparated and completely-peeled garlic cloves. Hanji-type garlic required higher or pressure difference to separate cloves from garlic bulbs than nanji-type garlic. On the other hand, protective leaves(skin) from the cloves were peeled more easily in case of hanji-type garlic. As a result of three consecutive peeling operations, the proportion of completely-peeled garlic cloves changed in the order of 80.1, 82.6, 84.1% in case of hanji-type, and 19.6, 29.1, 40.2% in case of nanji-type garlic.

Comparison of Dosimetry Protocols in High Energy Electron Beams (고에너지 전자선에 대한 표준측정법간의 비교)

  • 박성용;서태석;김회남;신동오;지영훈;군수일;이길동;추성실;최보영
    • Progress in Medical Physics
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    • v.9 no.4
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    • pp.267-276
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    • 1998
  • Any detector inserted into a phantom should have such a geometry that it caused as small as possible perturbation of the electron fluence. Plane parallel chambers meet this requirement better than other chambers of configurations. IAEA protocol recommends the use of plane parallel chambers for this reason. However, the cylindrical chambers are widely used for convenient. The purpose of this study is to evaluate the absorbed dose due to the differences of four different dosimetry protocols such as IAEA protocol using cylindrical chamber, TG 21 protocol using cylindrical chamber, Markus protocol using plane parallel chamber, and TG 39 report for the calibration of plane parallel chamber in electron beams. Depth-ionization measurements for the electron beams of nominal energy 6, 9, 12, 15, and 18 MeV from Siemens accelerator with a 10$\times$10 cm$^2$ field size were made using a radiation field analyser with 0.125 cc ion chamber. Dosimetric measurements by IAEA and TG 21 protocol were made with a farmer type ionization chamber in solid water for each electron energy, respectively. Dosimetric measurements by Markus protocol were made with a plane parallel ionization chamber in solid water for each electron energy, respectively. The cavity-gas calibration factor for the plane parallel chamber was obtained with the use of 18 MeV electron beam as guided by TG 39 report. Dosimetric measurements by TG 39 were performed with a plane parallel ionization chamber in solid water for each electron energy, respectively. For all the energies and protocols, measurements were made along the central axis of the distance of 100 cm (SSD = 100 cm) with 10$\times$10 cm$^2$ field size at the depth of d$_{max}$ for each electron beam, respectively. In the case of 18 MeV, the discrepancy of 0.9 % between IAEA and TG 21 was found and the two protocols were agreed within 0.7 % for other energies. In the case of 18 MeV and 6 MeV, the discrepancies of $\pm$ 0.8 % between Markus and TG 39 was found, respectively and the two protocols were agreed within 0.5 % for other energies. Since the discrepancy of 1.6 % between cylindrical and plane parallel chamber was found for 18 MeV, it is suggested to get the calibration factor using other method as guided. by TG 39.9.

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Characteristics of Detectors for Measurements of Photon Depth Doses in Build-Up Region (선량보강(Build-up) 영역에서의 광자선 깊이선량률 측정을 위한 검출기의 특성 비교)

  • Kang Sei-Kwon;Park Suk Won;Oh Do Hoon;Park Hee Chul;Kim Su Ssan;Bae Hoonsik;Cho Byung Chul
    • Progress in Medical Physics
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    • v.16 no.2
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    • pp.77-81
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    • 2005
  • To determine the appropriate method out of various available methods to measure build-up doses, the measurements and comparisons of depth doses of build-up region including the surface dose were executed using the Attix parallel-plate ionization chamber, the Markus chamber, a cylindrical ionization chamber, and a diode detector. Based on the measurements using the Attix chamber, discrepancies of the Markus chamber were within $2\%$ for the open field and increased up to $3.9\%$ in the case of photon beam containing the contaminant electrons. The measurements of an cylindrical ionization chamber and a diode detector accord with those of the Attix chamber within $1.5\%\;and\;1.0\%$ and after those detectors were completely immersed in the water phantom. The results suggest that the parallel-plate chamber is the best choice to measure depth doses in the build-up region containing the surface, however, using cylindrical ionization chamber or diode detector would be a reasonable choice if no special care is necessary for the exact surface dose.

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Chamber-to-chamber Variations in the Same Type of a Cylindrical Chamber for the Measurements of Absorbed Doses (흡수선량 측정 시 동종 원통형 이온함에서 이온함 간 변화)

  • Kim, Seong-Hoon;Huh, Hyun-Do;Choi, Sang-Hyun;Kim, Hyeog-Ju;Lim, Chun-Il;Shin, Dong-Oh;Choi, Jin-Ho
    • Progress in Medical Physics
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    • v.21 no.1
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    • pp.120-125
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    • 2010
  • For the measurements of an absorbed dose using the standard dosimetry based on an absorbed dose to water the variety of factors, whether big, small, or tiny, may influence the accuracy of dosimetry. The beam quality correction factor ${\kappa}_{Q,Q_0}$ of an ionization chamber might also be one of them. The cylindrical type of ionization chamber, the PTW30013 chamber, was chosen for this work and 9 chambers of the same type were collected from several institutes where the chamber types are used for the reference dosimetry. They were calibrated from the domestic Secondary Standard Dosimetry Laboratory with the same electrometer and cable. These calibrated chambers were used to measure absorbed doses to water in the reference condition for the photon beam of 6 MV and 10 MV and the electron beam of 12 MeV from Siemens ONCOR. The biggest difference among chambers amounts to 2.4% for the 6 MV photon beam, 0.8% for the 10 MV photon beam, and 2.4% for the 12 MeV electron beam. The big deviation in the photon of 6 MV demonstrates that if there had been no problems with the process of measurements application of the same ${\kappa}_{Q,Q_0}$ to the chambers used in this study might have influenced the deviation in the photon 6 MV and that how important an external audit is.

Fabrication of a 18cm long YBCO coated conductor using a cylindrical tape holder in a double chamber co-evaporation system (이중 챔버를 가진 동시증발 시스템 내에서 실린더 홀더를 이용한 18cm 길이의 YBCO coated conductor의 제작)

  • Oh, Sang-Hyun;Jung, Kook-Chae;Youm, Do-Jun
    • 한국초전도학회:학술대회논문집
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    • v.9
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    • pp.322-325
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    • 1999
  • We fabricated 18cm YBCO coated conductor comprising a YBCO superconducting film and CeO$_2$/YSZ/CeO$_2$ buffer films deposited on a biaxially textured Ni tape. For those film fabrications, we developed a new method, the cylindrical holder in a double chamber. This is alternative to the reel-to-reef method which is commonly tried to fabricate a long YBCO coated tape. We will discuss about the superconducting properties of the 18cm long YBCO coated tapes.

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Acoustic, entropy and vortex waves in a cylindrical tube with variable section area (단면적이 변하는 실린더 관에서의 음향, 엔트로피 및 와류 파동)

  • Lebedinsky Ev. V.;Cho Gyu-Sik
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2004.10a
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    • pp.27-35
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    • 2004
  • In this paper a method for finding solution of acoustic, vortex and entropy wave-equations in a cylindrical tube with variable section area was suggested under the consideration of that the high frequency instability in a rocket engine combustion chamber is an acoustic phenomena, which is coupled with combustion reaction, and that a combustion chamber and exhaust nozzle are usually shaped cylindrically. As a consequence of that some method, which enable the quantitative analysis of the influence of entropy and vortex waves to acoustic wave, was suggested.

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Study on Calorimeteric Chamber for Heat Flux Measurement in Liquid Rocket Engine (액체로켓 추력실에서 heat flux측정을 위한 calorimeteric chamber의 연구)

  • Kim, Byeong Hun;Park, Hui Ho;Hwang, Su Gwon;Kim, Yu
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.31 no.4
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    • pp.76-81
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    • 2003
  • To investigate the convective heat transfer phenomena inside the Lox/Kerosene liquid rocket combustion chamber, hot fire tests were performed by using a water-cooled calorimetric chamber. The calorimetric chamber consists of one cylindrical section and nozzle section with independent cooling passage. To measure the heat flux, thermocouples were installed inlet and outlet of cooling passage of each section. The investigated range of combustion chamber pressure is from 100 psi to 300psi at fixed O/F ratio of 2.0 and radiation heat transfer from the hot gas to the surface is not considered. The measured heat flux was almost linearly depended on the chamber pressure.

Heat Transfer in the Combustion Chamber for the Compact Hot-Water Boiler (콤팩트 온수 보일러 연소실의 열전달 특성)

  • Cho, Jung-Hwan;Seo, Tae-Beom;Kim, Wook-Jung;Kim, Chang-Ju
    • Proceedings of the KSME Conference
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    • 2001.06d
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    • pp.459-464
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    • 2001
  • A mathematical model has been developed to describe the turbulent and reversed flow with convective heat transfer in a cylindrical combustion chamber. By using the mathematical model for high temperature flow enables the trends in overall heat transfer rates to be predicted. The model was applied to the design of the combustion chamber. The influences of the size of air inlet and inlet velocity were investigated for process optimization. Through modelling work it is found that the heat transfer rate to the chamber wall may be enhanced by adjusting the air flow and heat transfer pattern through selecting the air inlet condition. Internal plate has less influence to the heat transfer characteristics.

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