• 설비공학논문집
• /
• 제20권1호
• /
• pp.11-16
• /
• 2008

Infrared (IR) detectors are widely used for such applications as thermoelastic stress analysis, medical diagnostics and temperature measurement. Infrared detectors commonly need to be refrigerated below 80 K, and thus a cooling system should be equipped together with the detector system. The cooling load, which should be removed by the cooling system to maintain the nominal operating temperature of the detector, critically depends on the insulation efficiency of the cryochamber housing the detector. Thermal load of a cryochamber is attributed to the conduction heat transfer through a cold finger, the gases conduction and radiation heat transfer. The thermal loads of an infrared detector cryochamber with a radiation shield are investigated experimentally in present study. Since the effect of radiation heat transfer on thermal loads is significant, radiation shields is installed in the cold finger part to protect heat input through radiation.

• 한국안전학회지
• /
• 제16권1호
• /
• pp.1-8
• /
• 2001

All objects emit thermal radiation and this radiation is the basis of the techniques used to detect flames. The usual phenomena occurring in the initial stage of the fire are generally invisible products of a combustion and visible smoke. Liquid or gaseous materials do not undergo a smoldering stage so that fires develop very rapidly. Also, the heat generated by the initial flames is usually not sufficient to activate a heat detector. In this case the most effective criterion for automatic fire detection is the flame. According to the fire regulation of korea, the compulsory standard provided that a flame detector shall be installed in a place that the attachment height of detector is higher than 20 m, chemical plants, hangar, refinery, etc.. The results of the research and development are discriminated between a flame and other radiant emitters, developed a UV detector tube contains an inert gas which absorbs UV radiation, developed PZT pyroelectric element is based on the use of photovoltanic cell, developed IR band-pass filter that only allow a 4.3 $\mu\textrm{m}$ radiation wavelength to reach the sensors and developed UV-IR combination flame detector combined into a single detection device.

• 대한방사선방어학회:학술대회논문집
• /
• 대한방사선방어학회 2010년도 춘계 학술발표회 및 심포지엄
• /
• pp.70-71
• /
• 2010

• Nuclear Engineering and Technology
• /
• 제52권10호
• /
• pp.2151-2161
• /
• 2020

The study presents a review of research advancements in the field of gamma radiation detection systems for emergency radiation monitoring, particularly two major sub-systems namely (i) the radiation detector and (ii) the detection platform - air-borne and ground-based. The dynamics and functional characteristics of modern radiation detector active materials are summarized and discussed. The capabilities of both ground-based and aerial vehicle platforms employed in gamma radiation monitoring are deliberated in depth.

• Journal of Radiation Protection and Research
• /
• 제41권2호
• /
• pp.105-109
• /
• 2016

Background: For an accelerator-based BNCT, we have fabricated a new detector consisting of quartz optical fibers that have excellent radiation-resistant characteristics. Materials and Methods: The developed detectors were irradiated at Kyoto University Research Reactor. Results and Discussion: The experimental results showed that the new detector had good output linearity for the neutron intensity, and the response of the new detector did not decrease during the irradiation. Conclusion: The new detector consisting of quartz optical fibers can be applied to measurement of neutron field of an accelerator-based BNCT.

• 한국정보통신학회:학술대회논문집
• /
• 한국정보통신학회 2014년도 춘계학술대회
• /
• pp.707-709
• /
• 2014

핵폭발이나 원자력 발전시설 사고와 같이 대규모 방사선사고 발생 시 주변지역은 감응방사선 또는 방사선 낙진으로 인해 오염된다. 이러한 오염지역을 원격에서 탐지하여 오염물질에 대한 분포 및 오염 정도를 확보한다면 오염물질 제거뿐만 아니라 오염에 대한 피해를 최소화 할 수 있다. 본 논문에서는 오염 물질을 탐지하기 위한 스테레오 검출기 개발의 일환으로 MCNP코드를 이용하여 검출기의 차폐체 및 콜리메이터를 설계하고 교정된 감마선 조사시설을 통해 일정한 선량의 감마선을 조사하여 차폐체 및 콜리메이터에 대한 영향을 분석하였다. 본 논문의 결과는 방사선 탐지를 위한 효율적인 검출기 구조를 설계를 위한 기초자료로 활용될 것이다.

• Journal of Radiation Protection and Research
• /
• 제49권2호
• /
• pp.85-90
• /
• 2024

Background: This study focuses on the fabrication and characterization of quasi-hemispherical Cd_0.9Zn_0.1Te (CZT) detector for gamma-ray spectroscopy applications, aiming to contribute to advancements in radiation measurement and research. Materials and Methods: A CZT ingot was grown using the vertical Bridgman technique, followed by proper fabrication processes including wafering, polishing, chemical etching, electrode deposition, and passivation. Response properties were evaluated under various external bias voltages using gamma-ray sources such as Co-57, Ba-133, and Cs-137. Results and Discussion: The fabricated quasi-hemispherical CZT detector demonstrated sufficient response properties across a wide range of gamma-ray energies, with sufficient energy resolution and peak distinguishability. Higher external bias voltages led to improved performance in terms of energy resolution and peak shape. However, further improvements in defect properties are necessary to enhance detector performance under low bias conditions. Conclusion: This study underscores the efficacy of quasi-hemispherical CZT detector for gamma-ray spectroscopy, providing valuable insights for enhancing their capabilities in radiation research field.

• Nuclear Engineering and Technology
• /
• 제52권7호
• /
• pp.1524-1531
• /
• 2020

The aim of this work is to develop a Geiger-Muller (GM) detector system for robot to look for a radioactive source in case of a nuclear emergency or in a high radiation environment. In order to find a radiation source easily, a detector system, including 3 detectors, was designed to search γ-ray radiation sources autonomously. First, based on GEANT4 simulation, radiation dose rates in 3 Geiger-Muller (GM) counters were simulated at different source-detector distances, distances between detectors and angles. Various sensitivity analyses were performed experimentally to verify the simulated designed detector system. A mono-energetic ¹³⁷Cs γ-ray source with energy 662 keV and activity of 1.11 GBq was used for the observation. The simulated results were compared with the experimental dose rate values and good agreements were obtained for various cases. Only based on the dose rates in three detectors, the radiation source with a specific source activity and angle was localized in the different location. A method was adopted with the measured dose rates and differences of distances to find the actual location of the lost γ-ray source. The corresponding angles of deviation and detection limits were calculated to determine the sensitivity and abilities of our designed detector system. The proposed system can be used to locate radiation sources in low and high radiation environments.

• Journal of Radiation Protection and Research
• /
• 제13권2호
• /
• pp.29-40
• /
• 1988

환경방사선 측정에 이용되는 휴대형 고순도 게르마늄검출기에 대한 스펙트럼-조사선량율 변환연산자를 원판형선원의 공간분포함수와 검출기의 평면에 대한 측정효율식을 적용하여 이론적으로 유도했다. 이와 같이 구한 변환연산자와 휴대형 고순도 게르마늄검출기를 이용해 한국에너지연구소내에서 방사선 조사선량율을 측정했다. 측정한 조사선량율을 이미 알려진 3'${\phi}\;{\times}$3'NaI(Tl) 섬광검출기에 대한 변환연산자를 적용해 NaI(Tl)검출기로 측정한 조사선량율과 가압형 이온전리함으로 측정한 값과 비교했다. 고순도 게르마늄 검출기로 얻은 결과는 NaI(Tl) 검출기와 가압형 이온전리함으로 얻은 값보다 약 17-29% 낮음을 보여주었다. 이 차이는 다른 문헌에서 보인 차이와 거의 같았다. 본 논문에서 제시한 스펙트럼-조사선량율 변환연산자는 탁상용 계산기로 쉽게 계산할 수 있으며 환경방사선의 측정에 사용되는 여러 검출기에 대해서도 쉽게 적용할 수 있는 장점이 있고 지각에서 방출되는 각 핵종별로 조사선량율을 구할 수 있는 장점이 있다.

• Nuclear Engineering and Technology
• /
• 제52권10호
• /
• pp.2346-2352
• /
• 2020

Dual-energy x-ray absorptiometry (DXA) is the noninvasive method to diagnose osteoporosis disease characterized by low bone mass and deterioration of bone tissue. Many global companies and research groups have developed the various DXA detectors using a direct photon-counting detector such as a cadmium zinc telluride (CZT) sensor. However, this approach using CZT sensor has some drawback such as the limitation of scalability by high cost and the loss of efficiency due to the requirement of a thin detector. In this study, a SiPM based DXA system was developed and its performance evaluated experimentally. The DXA detector was composed of a SiPM sensor coupled with a single LYSO scintillation crystal (3 × 3 × 2 ㎣). The prototype DXA detector was mounted on the dedicated front-end circuit consisting of a voltage-sensitive preamplifier, pulse shaping amplifier and constant fraction discriminator (CFD) circuit. The SiPM based DXA detector showed the 34% (at 59 keV) energy resolution with good BMD accuracy. The proposed SiPM based DXA detector showed the performance comparable to the conventional DXA detector based on CZT.