• Journal of radiological science and technology
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• v.29 no.1
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• pp.13-19
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• 2006

The PET scanner can detect the photon pair arriving from the source in phantom. The number of light photons released by the crystal(scintillator-BGO or LSO). In recent scintillation crystals in block structures were incorporated into full ring systems, and their resulted marked improvement in spatial resolution and increase in a sensitivity to annihilations. The uniformity of the crystal sensitivity is very important to makes correct information of abnormal states in organs. These factors influenced by the dection efficiency of the scintillators. We have study about the uniformity of crystals to the annihilation, And study about the standard deviation to average counts. The relative standard deviation in central detector groups more uniformed than circumferenced detector groups. It is caused detected quanta of gamma ray by the geometrical factors of PET detector. PET cameras are available with different geometric arrangement and several parallel rings oriented in the axial direction. The center groups from 7th to 40th groups are comparatively uniform and sensitive. But at the circumferenced detectors decreased the sensitivity and uniformity.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.6 no.1
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• pp.45-50
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• 1981

Infrasonic transducer made with dielectric materials, such as polytetrafluoroethyleme(PTFE)film. The experimental result obtained that the response is within $\pm$1.5dB from 0.1Hz to 7KHz, and that sensitivities of typical transducer are fixed -60dB. The time constant of the transducer at room temperature is over 60 years, and the activation energy of the value of 1.1eV at 343K acquired. This transducer can have application to high-quality communication system, seismological observation etc.

• Journal of Radiation Protection and Research
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• v.27 no.1
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• pp.51-57
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• 2002

An electronic personal dosimeter(EPD) with hybrid type preamplifier adopting a semiconductor detector as a radiation detector has been developed, manufactured and test-evaluated. The radiation detection characteristics of this EPD has been performance-tested by using a reference photon radiation field. After several test-irradiations to a $^{137}Cs$ gamma radiation source the radiation detection sensitivity of this EPD appeared to be $3.8\;cps/Gy{\cdot}h^{-1}$. The linearity of radiation response was kept within 8% of the dose equivalent ranges of $10{\mu}Sv{\sim}4Sv$ and the angular dependence was under less than 4% in angles of ${\pm}60^{\circ}$. It was confirmed that the energy response range was in $60{\sim}1,250keV$ given in the ISO standard. This EPD satisfied the international criteria for the EPD in the mechanical and the environmental performance test for 9 test categories according to IEC 61526.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.8 no.3
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• pp.83-90
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• 2009

This paper presents the design and measurement of a flight model for a Ku-Band Linearized Channel Amplifier. All MMICs, Variable Gain Amplifier (VGA), Variable Voltage Attenuator ('.IVA), Branch line Coupler and Detector for Pre-distorter are fabricated using a Thin-Film Hybrid process. The performance of the fabricated module is verified through the radio frequency circuit simulation tool and electrical function test in space environment.

• Analytical Science and Technology
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• v.6 no.4
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• pp.411-415
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• 1993

A method for UV labeling of fatty acids with 2-bromoacetyltriphenylene using 18-crown-6-ether as a catalyst is described. The procedure is rapid, simple, quantitative and applicable to the HPLC analysis of fatty acids with UV detector. They have high molar absorptivity and their detection limit was about 1ng level. Nine derivatives of saturated fatty acid($C_{12}-C_{22}$) were separated on reverse-phase column(${\mu}$-Bondapak C-18) using acetonitrile-water gradient.

• The Bulletin of The Korean Astronomical Society
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• v.39 no.2
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• pp.101.2-101.2
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• 2014

적외선 파장 대역에서 관측되는 우주배경복사의 요동은 초기 우주가 재이온화되는 시기에 존재하였던 우주 최초의 별 또는 은하에서 기원한다고 믿어진다. 적외선우주배경복사 관측을 위해서는 배경의 잡음이 되는 별, 은하, 황도광등을 제거하고 희미한 배경을 검출해야 하므로 광시야, 고감도로 광학에서 근적외선까지 다파장으로 관측하는 기능이 필요하다. CIBER2는 이러한 적외선우주배경복사 관측을 위해 개발되고 있는 NASA 사운딩로켓 탑재용 적외선카메라 시스템이다. 2009년부터 2013년까지 4차례에 걸쳐 성공적으로 발사된 CIBER를 업그레이드한 관측기기로써 한국 KASI, 미국 Caltech, 일본 ISAS가 공동으로 개발하고 있다. CIBER2는 28.5cm의 주경에 광분배기를 사용하여 3대의 카메라가 장착되는 형상을 이루고 있으며 각 카메라에는 $2K{\times}2K$ H2RG 검출기 위에 2개의 밴드 필터를 부착하여 0.6 - 2.1 um의 파장 대역을 6개의 구간으로 나누어 관측한다. 각 밴드의 시야각은 $1.1{\times}2.2$도이다. CIBER2는 현재 최종 설계를 마치고 각 서브시스템 별 제작 단계에 있으며, 조립 및 시험을 거쳐 2015년에 미국 화이트샌드 미사일기지에서 발사될 예정이다.

• Journal of the Korean Society of Radiology
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• v.3 no.3
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• pp.37-40
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• 2009

In this study, we made a high efficiency x-ray detecting sensor using the lead oxide(PbO) that are used in direct method of x-ray detector. PbO with nano size particles is produced by sol-gel method for high efficiency. The produced PbO with nano size is deposited on ITO(Induim Tin Oxide) glass in several temperature using the PIB(particle-in-binder) method. The thickness of the deposited PbO is about $200{\mu}m$. Through the measurement of dark current, sensitivity and SNR(Signal To Noise Ratio), an electrical properties of the produced PbO film are analyzed. Therefore, we show that an electrical properties are changed according to a temperature and that the PbO film that was treated at $500^{\circ}C$ in O2 atmosphere is the most high efficiency x-ray detecting sensor.

• Progress in Medical Physics
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• v.5 no.2
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• pp.57-68
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• 1994

Purpose : The purposes are to discuss the reason to measure dose distributions of circular small fields for stereotactic radiosurgery based on medical linear accelerator, finding of beam axis, and considering points on dosimetry using home-made small water phantom, and to report dosimetric results of 10MV X-ray of Clinac-18, like as TMR, OAR and field size factor required for treatment planning. Method and material : Dose-response linearity and dose-rate dependence of a p-type silicon (Si) diode, of which size and sensitivity are proper for small field dosimetry, are determined by means of measurement. Two water tanks being same in shape and size, with internal dimension, 30${\times}$30${\times}$30cm$^3$ were home-made with acrylic plates and connected by a hose. One of them a used as a water phantom and the other as a device to control depth of the Si detector in the phantom. Two orthogonal dose profiles at a specified depth were used to determine beam axis. TMR's of 4 circular cones, 10, 20, 30 and 40mm at 100cm SAD were measured, and OAR's of them were measured at 4 depths, d$\sub$max/, 6, 10, 15cm at 100cm SCD. Field size factor (FSF) defined by the ratio of D$\sub$max/ of a given cone at SAD to MU were also measured. Result : The dose-response linearity of the Si detector was almost perfect. Its sensitivity decreased with increasing dose rate but stable for high dose rate like as 100MU/min and higher even though dose out of field could be a little bit overestimated because of low dose rate. Method determining beam axis by two orthogonal profiles was simple and gave 0.05mm accuracy. Adjustment of depth of the detector in a water phantom by insertion and remove of some acryl pates under an auxiliary water tank was also simple and accurate. TMR, OAR and FSF measured by Si detector were sufficiently accurate for application to treatment planning of linac-based stereotactic radiosurgery. OAR in field was nearly independent of depth. Conclusion : The Si detector was appropriate for dosimetry of small circular fields for linac-based stereotactic radiosurgery. The beam axis could be determined by two orthogonal dose profiles. The adjustment of depth of the detector in water was possible by addition or removal of some acryl plates under the auxiliary water tank and simple. TMR, OAR and FSF were accurate enough to apply to stereotactic radiosurgery planning. OAR data at one depth are sufficient for radiosurgery planning.

• Proceedings of the KIEE Conference
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• 2003.07d
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• pp.2022-2024
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• 2003

본 논문에서는 진동형 마이크로 자이로스코프를 위한 폐루프 제어기를 설계하였으며 실험을 통하여 설계된 제어기의 성능을 검증하였다. 일반적으로 진동형 자이로스코프를 동작시키기 위해서는 구동축과 검출축의 공진 모드가 일치되도륵 설계를 하며 높은 감도를 얻기 위해서는 이 두 모드의 Q값이 클수록 유리하다. 하지만 이러한 개루프 상에서 동작 하에서는 대역폭과 선형성 등의 성능에 제약을 가져오게 되며 이를 개선하기 위해 폐루프 제어기가 필요하다. 본 논문에서는 진공도에 따른 Q값의 변화와 이에 따른 제어기의 성능을 분석하였으며 실험 결과로부터 설계된 제어기가 만족할만한 성능의 개선을 가져옴을 확인하였다.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.03a
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• pp.136-136
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• 2003

카본나노튜브는 상용되는 기존의 센서에 비해 표면적이 넓어 감도가 놀고 응답속도가 빠르다. 또한 나노 스케일의 크기를 가지므로 고직접화를 실현할 수 있으며 기능복구성이 뛰어나 상온동작을 통한 저전력화가 가능하다. 본 실험에서는 아크방전법으로 합성한 카본나노튜브를 가스센서로 제작하여 상온에서 NH$_3$, NO 가스와의 반응 특성을 평가하였다. 또한 origin soot와 이를 정제한 purified CNT를 SEM(주사전자현미경), TEM(투과전자현미경), Raman scattering spectroscopy(라만 산란 분광기)를 통해 재료적 특성을 조사하고 이를 가스 감응 곡선과 연관하여 비교, 분석하였다. 전극에 CNT막을 형성시키기 위해 3g의 N,N dimethylformamide 용액에 CNT 10mg을 분산시킨 후 2시간동안 초음파 처리하였다. 이 용액을 mask를 이용해 전극 위에 막을 형성시킨 후 20$0^{\circ}C$에서 열처리하였다. 이렇게 제조된 origin soot와 purified CNT센서는 flow system을 이용하여 측정하였고 $N_2$분위기 하에서 센서를 안정화시킨 후 측정가스와의 반응을 살펴보았다 센서의 반응속도, 회복속도, 감도 등의 측정결과 origin soot는 NH$_3$ 25ppm에서 20%, purified CNT는 1%의 감도를 보여 20배 높은 감도를 보았다. NO 25ppm의 경우에도 origin soot가 8%, purified CNT는 0.8%의 감도를 보여 10배 높은 감도를 보였다. 이는 탄소입자가 많은 origin soot가 purified CNT 보다 표면적이 넓어 보다 많은 가스 흡착 싸이트를 가지기 때문이다. 하지만 origin soot는 반응시간과 회복속도가 Purified CNT 보다 2배 이상 느려 표면적 증가에 따른 가스 흡착과 탈착 능력이 떨어짐을 알 수 있었다. 또한 CNT와 가스사이의 전하 이동 방향에 따라 NH$_3$는 양의 감도를 NO는 음의 감도를 보였다 이는 전하의 이동 방향에 따라 전하와 캐리어 사이의 결합 및 해리가 일어나게 되고 결국 카본나노튜브 내의 캐리어 수를 증감시킴에 따라 나타나는 현상이다. 이러한 가스의 감도는 농도에 따라 증가하였으며 origin soot를 이용하여 1ppm이하의 NH$_3$ 가스를 검출할 수 있었다.