• 한국의학물리학회지:의학물리
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• 제9권1호
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• pp.29-35
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• 1998

There has been necessity of an air free ionization chamber using the gold-crystal-aluminium plates, henceforth called the crystal chamber. The crystal chamber formed of parallel plates is very small in size and has more response for absorbed dose of therapeutic radiation beams. The gold plate on the crystal facing the photon and electron beam acts as an intensifier of signals and crystal plate as an ionization medium respectively. Both the copper guard ring and the aluminum collecting electrode are connected to an electrometer. Using high energy photon (6, 15 MV) and electron (9, 12, 15, 18 MeV) beams, the responses of the crystal chamber are evaluated against a PTW Farmer-type chamber at a field size of 10${\times}$10cm$^2$ and 100 cm SSD. The responses of crystal chamber for therapeutic radiation electron and photon beams are greater in magnitude by several order than Farmer. The crystal chamber has good linearity without correction factor C$\_$t,p/ with respect to the signals, a reading reproduction with good accuracy and precision less than 0.5%, and has other useful functions in measuring radiation beams.

• Journal of Radiation Protection and Research
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• 제41권3호
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• pp.222-228
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• 2016

Background: We are developing a small size dosimeter for dose estimation in particle therapies. The developed dosimeter is an optical fiber based dosimeter mounting an radiation induced luminescence material, such as an OSL or a scintillator, at a tip. These materials generally suffer from the quenching effect under high LET particle irradiation. Materials and Methods: We fabricated two types of the small size dosimeters. They used an OSL material Eu:BaFBr and a BGO scintillator. Carbon ions were irradiated into the fabricated dosimeters at Heavy Ion Medical Accelerator in Chiba (HIMAC). The small size dosimeters were set behind the water equivalent acrylic phantom. Bragg peak was observed by changing the phantom thickness. An ion chamber was also placed near the small size dosimeters as a reference. Results and Discussion: Eu:BaFBr and BGO dosimeters showed a Bragg peak at the same thickness as the ion chamber. Under high LET particle irradiation, the response of the luminescence-based small size dosimeters deteriorated compared with that of the ion chamber due to the quenching effect. We confirmed the luminescence efficiency of Eu:BaFBr and BGO decrease with the LET. The reduction coefficient of luminescence efficiency was different between the BGO and the Eu:BaFBr. The LET can be determined from the luminescence ratio between Eu:BaFBr and BGO, and the dosimeter response can be corrected. Conclusion: We evaluated the LET dependence of the luminescence efficiency of the BGO and Eu:BaFBr as the quenching effect. We propose and discuss the correction of the quenching effect using the signal intensity ratio of the both materials. Although the correction precision is not sufficient, feasibility of the proposed correction method is proved through basic experiments.

• Journal of Advanced Marine Engineering and Technology
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• 제25권2호
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• pp.395-402
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• 2001

The gasoline engine tends to high performance, fuel economy, small-sized. Therefore, it is necessary to solve the problems on thermal load, abnormal combustion, etc, in the engine, Thine film instantaneous temperature measurement probe was made. And the manufactural method of probe was established. The instantaneous surface temperatures in the constant volume combustion chamber were measured by this probe and the heat flux was obtained by Fourier analysis. The authors measured the wall temperature of combustion chamber and computed the heat flux through the cylinder wall in order to understand the combustion characteristics depending on height of probe. For achieving this goal, the thin film instantaneous temperature probe was developed for analyzing the instantaneous surface wall temperature and unsteady heat flux on the constant volume combustion chamber.

• 한국해양공학회지
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• 제13권3B호
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• pp.47-55
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• 1999

A study on swirl chamber for diesel engine is to realize lower fuel consumption and exhaust emission than the current marketing engines. Author formerly reported the performance characteristics of small IDI diesel engine with swirl chamber by changing the jet passage area and its angle, and the depth and shape of the piston top cavity. Following after the first report, in this paper, the characteristics of fuel consumption, soot emission, and exhaust gas temperature were examined and analyzed after dimension of jet passage area expanded to $70.1mm^2$ The results were that the optimum values of the jet passage area depending on the depth of the piston top cavity were different at each engine speeds and loads, and in accordance with application of engine running conditions they were able to be selected as optimum dimensions of each design parameters.

• Journal of Chest Surgery
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• 제16권4호
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• pp.547-554
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• 1983

Implantation of Dual Chamber Pacemakers Which sense in the Atrium and the Ventricle, and sequentially or synchronously trigger impulses in the both chambers, has led us to the near realization of the ideal "Physiologic Pacing". We have experienced two cases of implantation of Dual chamber pacemaker in September and October, 1983. One patient was a 21-year-old male who had postoperative complete heart block since he was taken Total correction of TOF in May, 1983 . We implanted transvenously a dual chamber pacemaker, VDD type, through the left subclavian vein. In the other patient who came to the emergency room for partial obstruction of small bowels with severe abdominal pain, nausea and vomiting, in whom heart block was found, we implanted a DDD type pacemaker through the left subclavian puncture. The pacemakers have been functioning well postoperatively for more than two months, and the conditions of patient were uneventful.

• 한국콘텐츠학회논문지
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• 제15권12호
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• pp.1-7
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• 2015

현재까지 개발된 항재밍 위성항법장치는 주로 대형 무반향 챔버 및 필드시험을 통하여 검증하였다. 대형 무반향 챔버를 이용할 경우 노이즈 등 외부환경에 독립적으로 장비를 검증할 수 있는 장점이 있지만 높은 비용과 챔버 시설 가용 문제 등의 단점이 있다. 그리고 필드시험의 경우 실제 재밍환경과 유사하게 시험할 수 있는 장점이 있지만 군용장비의 경우 보안 문제 및 항상 동일한 조건으로 시험을 할 수 없는 단점이 있다. 본 논문에서는 기존 점검 시스템의 단점을 극복할 수 있는 새로운 항재밍 위성항법장치 점검 시스템을 제안하였다. 제안하는 점검시스템은 크게 소형 챔버, 재밍 분배기, 재밍신호 발생기, 위성 모의기로 구성된다. 소형 챔버에는 다수 재밍을 모의하기 위해 다수의 안테나를 내부에 설치하였고, 다수의 재밍 신호를 제어하기 위한 재밍 분배기를 새롭게 설계하였다. 점검 시스템의 자체 성능 시험과 항재밍 위성항법장치와의 연동 시험을 통해 제안한 점검 시스템의 신뢰성을 확인하였다.

• 한국의학물리학회지:의학물리
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• 제22권4호
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• pp.216-223
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• 2011

최근 PTW사에서는 물등가물질로 구성되어 있고, 측정체적(sensitive volume, $0.002cm^3$)이 매우 작은 MicroLion 액체이온함을 내놓았다. 본 연구의 목적은 외부방사선 치료용 광자빔에 대해 MicroLion 액체이온함의 선량선형성, 선량률의존성, 공간분해능, 그리고 출력인수와 같은 선량측정학적 특성을 조사하는 것이다. 이 결과를 Semiflex 이온함($0.125cm^3$), Pinpoint 이온함($0.015cm^3$), 다이오드 검출기($0.0025mm^3$)의 결과와 비교분석하여 소조사면 측정에 적절한지를 평가하고 자 하였다. Varian clinac 2300 C/D의 6 MV 광자빔에서 측정하였으며, MP3 물팬톰(PTW, Freiburg)을 이용하였다. 공간분해능은 반음영(penumbra)을 측정하여 평가하였으며, $0.5{\times}0.5cm^2$에서 $10{\times}10cm^2$까지 다양한 조사면에 대하여 측정하였다. 출력인수는 $0.5{\times}0.5cm^2$에서 $40{\times}40cm^2$에 대하여 측정하였다. 선량에 따른 MicroLion 액체이온함의 측정값은 선형적인 비례성을 보였다. 그러나 선량률은 100 MU/min와 600 MU/min에 의한 측정값의 차이가 최대 5%의 차이를 보였으며, 선량율이 커질수록 출력선량이 작아지는 결과를 보였다. 공간분해능의 경우 조사면 $0.5{\times}0.5cm^2$에서 $10{\times}10cm^2$까지의 측방선량분포 비교에서 Semiflex 이온함을 제외한 다른 모든 검출기들의 경우 2% 이내에서 일치하였다. 출력선량은 $2{\times}2cm^2$에서 $10{\times}10cm^2$ 조사면에서 Semiflex 검출기 대비 모든 검출기가 2% 이내에서 잘 일치하였다. 연구 결과 MicroLion 액체이온함은 물등가물질로 이루어져 있으며, 감응 면적이 매우 작기 때문에 소조사면에서 매우 유용할 것으로 사료된다.

• KIEAE Journal
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• 제9권4호
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• pp.17-22
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• 2009

It is common to design the duct branches where to supply the required air flow for individual room in residential apartment house. However it is difficult to adjust the air volume adequately in small air duct branches in residential ventilation system. The purpose of this study is to figure out the performance of Multidrop chamber coupling system for the residential ventilation system. The experiments were designed to simulate apartment of $84m^2$ and established multidrop chamber duct and general duct on the ceiling of the apartment. Distribution performance of air supply rate were evaluated in this experiments. As a result, distribution performance of air supply rate in the general duct is different from designed air supply rate by about 35% ~ 50% and about 10% in the multidrop chamber system. In additional the sound insulation performance of the multidrop chamber system decreased about 20% compared with general duct system. Therefore, the multidrop chamber system is considered to satisfy proper air supply rate of each room and to improve the sound insulation performance in apartment Houses.

• 한국자동차공학회논문집
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• 제8권1호
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• pp.48-53
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• 2000

The effects of the internal flow in a diesel injection nozzle on the atomization of the spray has been investigated experimentally. Flow visualization was made using a transparent acrylic model nozzle. And also, measurement of the sac chamber pressure was made for clartfying the effect of pressure fluctuation in the sac chamber on the wpray behaviors. The geometry of the model nozzle was scaled up 10 times of the actual nozzle and the injection pressure for the model nozzle was adjusted so as to achieve a Reynolds number at the discharge hole which was the same as the actual nozzle. Polystyrene tracers, a laser sheet light and a still/high speed video camera were used to visualize the flow pattern in the sac chamber. When the needle lift was small, the high turbulence in the sac chamber generated by the high velocity seat flow made the spread angle of the spray large. Cavitation which arose in the sky chamber induced the pressure fluctuation and then affects the spread angle of the spray.

• Bulletin of the Korean Chemical Society
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• 제18권6호
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• pp.584-588
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• 1997

A new device to accurately deliver small amount of modifier into supercritical carbon dioxide fluid is described. Carbon dioxide, the most widely used mobile phase in supercritical fluid chromatography, is a relatively non-polar fluid, and hence the addition of small amount of polar modifiers could be necessary to migrate polar solutes. In this work, supercritical CO₂and modifier are delivered from the pump to a 100 μL mixing chamber in which a small magnetic bar is rotating. After passing through the mixing chamber, supercritical CO₂is changed to a new mobile phase with different polarity. The amount of modifier added into supercritical CO₂is measured by an amperometric microsensor, which is prepared from a thin film of perfluorosulfonate ionomer.