• Progress in Superconductivity
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• v.12 no.1
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• pp.41-45
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• 2010

Low temperature micro-calorimeters have been employed in the field of high resolution alpha spectrometers. These alpha detectors typically consist of a superconducting or metal absorber and a temperature sensor. The temperature sensor can be a transition edge sensor (TES), a metallic magnetic calorimeter (MMC) or other low temperature detectors for an accurate measurement of temperature change due to an alpha particle absorption. We report a recent study of the heat flow between a replaceable absorber and a temperature sensor. A piece of gold foil in $2.4{\times}2.7{\times}0.03\;mm^3$ is used as an absorber. A $40\;{\mu}m$ diameter Au:Er paramagnetic sensor is attached to another small piece of gold foil in $400{\times}200{\times}30\;{\mu}m^3$ to serve as the temperature sensor. This sensor assembly, Au:Er and gold foil, is placed on a miniature SQUID susceptometer in a gradiometric configuration. The thermal connection between the absorber and the sensor was made with three gold bonding wires. The measured thermal conductance shows a linear dependence to the temperature. The values are in a good agreement with Wiedemann-Franz type thermal conductance of the gold wires.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11b
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• pp.558-561
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• 2001

Vanadium oxide ($VO_x$) thin films are very good candidate material for uncooled infrared (IR) detectors due to their high temperature coefficient of resistance (TCR) at room temperature. But, the deposition of $VO_x$ thin films showing good electrical properties is very difficult in micro bolometer fabrication process using sacrificial layer removal because of its low process temperature and thickness of thin films less than $1000{\AA}$. This paper presents a new fabrication process of $VO_x$ thin films having high TCR and low resistance. Through sandwich structure of $VO_{x}(100{\AA})/V(80{\AA})/VO_{x}(500{\AA})$ by sputter method and post-annealing at oxygen ambient, we have achieved high TCR more than $-2%/^{\circ}C$ and low resistance less than $10K\Omega$ at room temperature.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11a
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• pp.558-561
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• 2001

Vanadium oxide ($VO_{x}$) thin films are very good candidate material for uncooked infrared (IR) detectors due to their high temperature coefficient of resistance (TCR) at room temperature. But, the deposition of $VO_{x}$ thin films showing good electrical properties is very difficult in micro bolometer fabrication process using sacrificial layer removal because of its low process temperature and thickness of thin films less than 1000${\AA}$. This paper presents a new fabrication process of $VO_{x}$ thin films having high TCR and low resistance. Through sandwich structure of $VO_{x}$(100${\AA}$)/V(80${\AA}$)/$VO_{x}$(500${\AA}$) by sputter method and post-annealing at oxygen ambient, we have achieved high TCR more than -2%/$^{\circ}C$ and low resistance less than $10K\Omega$ at room temperature.

• Journal of the Korean Society of Safety
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• v.22 no.3 s.81
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• pp.7-12
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• 2007

This paper presents the development of an electrical fire detection system using digital temperature and current detectors in order to sound for electrical fire in advance. As the demand for electricity is increasing and industrial facilities are getting more complex and larger in size, the losses of human life and property are on the increase by electrical fires. In order to prevent electrical fires, it is required to find out fire signatures, or electric signal of the overcurrent and overheating. Therefore, in this paper, developed is an electrical fire detection system based on the detection of signal for overcurrent and overheating to prevent electrical accidents in advance that happen in electrical wires. The developed system gives an alarm by computer monitor, speaker system and mobile phone before electrical fires occur and give severe damages to human beings and properties, and the system can be implemented and supplied for business and residental buildings at a low price. The usefulness and validity of the system, also, verified in this paper by case study and experiments.

• Journal of Magnetics
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• v.17 no.3
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• pp.172-175
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• 2012

We present a method for detecting very weak radiation by analyzing the inner structure of irradiated tris (lyoluminescence) materials using electron paramagnetic resonance (EPR) at low temperature. Organic materials have been looked into for use in emergency dosimetry of inhabitants around radiation accidents. However, this technology has never been applied to imperceptible radiation doses (< 0.5 Gy) because there is no proper method for detecting the change of inner structure of the subject bombed by very weak radiation at room temperature. Our results show that tris materials can be applied as a radiation detectors of very small radiation doses below 0.05 Gray, if EPR is used at low temperature (130 K ${\leq}$ T ${\leq}$ 270 K). The EPR signal intensity from the irradiated-tris sample had barely faded at all after 1 year.

• Proceedings of the IEEK Conference
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• 2000.06b
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• pp.115-118
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• 2000

Uncooled pyroelectric infrared detectors based on BST(B $a_{-x}$S $r_{x}$Ti $O_3$) thin films have been fabricated by RF magnetron sputtering and surface Micromachining technology. The detectors form BST thin film ferroelectric capacitors grown by RF magnetron sputtering on N/O/N(S $i_3$ $N_4$/ $SiO_2$/S $i_3$ $N_4$) membrane. The sputtered BST thin film exhibits highly c-axis oriented crystal structure that no poling treatment for sensing applications is required. This is an essential factor to increase the yield for realization of an infrared image sensor. surface-Micromachining technology is used to lower the thermal mass of the detector by giving maximum sensor efficiency Gold-black is evaporated on top of the sensing elements used the thermal evaporator. fabricated uncooled pyroelectric infrared detectors is highly output voltage at the low temperature(1$^{\circ}C$).).).

• Progress in Medical Physics
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• v.33 no.2
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• pp.11-24
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• 2022

X-ray detection has widely been applied in medical diagnostics, security screening, nondestructive testing in the industry, etc. Medical X-ray imaging procedures require digital flat detectors operating with low doses to reduce radiation health risks. Recently, metal halide perovskites (MHPs) have shown great potential in high-performance X-ray detection because of their attractive properties, such as strong X-ray absorption, high mobility-lifetime product, tunable bandgap, low-temperature fabrication, near-unity photoluminescence quantum yields, and fast photoresponse. In this paper, we review and introduce the development status of new perovskite X-ray detectors and imaging, which have emerged as a new promising high-sensitivity X-ray detection technology. We discuss the latest progress and future perspective of MHP-based X-ray detection in medical imaging. Finally, we compare the conventional detection methods with quantum-enhanced detection, pointing out the challenges and perspectives for future research directions toward perovskite-based X-ray applications.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.3
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• pp.439-447
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• 2002

The microchannel flow in miniature TCDs (thermal conductivity detectors) is investigated numerically. The solutions based on the boundary layer approximation are not very accurate in the region of the duct inlet for low Reynolds numbers. In this study, two-dimensional Navier-Stokes equations are considered to analyze the gas flow in a miniature TCD. Effects of channel size, inlet and boundary conditions on the heat transfer rate are examined. When the gas stream is not preheated, the distances for a miniature TCD to reach the conduction-dominant region for duct flow are found to be approximately two and three times the thermal entry length for duct flow with constant properties, respectively, leer constant wall temperature and constant wall heat flux boundary conditions. If the gas temperature at the channel inlet is close to the mean gas temperature in the conduction-dominant region, the entrance region is much shorter compared to other cases considered in this study.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.11a
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• pp.207-207
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• 2003

Uncooled infrared(IR) detectors that use a microbolometer with a large focal-plane array(FPA) have been developed with surface micromachining technology. There are many materials for microbolometers, such as metals, vanadium oxide, semiconductors and superconductors. Among theses, vanadium oxide is a promising material for uncooled microbolometers due to it high temperature coefficient of resistance(TCR) at room temperature. It is, however, is very difficult to deposit vanadium oxide thin films having a high TCR and low resistance because of the process limits in microbolometer fabrication. In general, vanadium oxides have been applied to microbolometer in mixed phases formed by ion beam deposition methods at low temperature with TCR in the range from -1.5 to -2.0%K.

• IEMEK Journal of Embedded Systems and Applications
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• v.12 no.2
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• pp.97-103
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• 2017

Thermal imaging is mainly used in military equipment required for night observation. In particular, technologies of uncooled thermal imaging detectors are being developed as applied to low-cost night observation system. Many system integrators require different specifications of the uncooled thermal imaging camera but their development time is short. In this approach, EOSYSTEM has developed a small size, TEC-less uncooled thermal imaging camera module with $32{\times}32mm$ size and low power consumption. Both domestic detector and import detector are applied to the EOSYSTEM's thermal imaging camera module. The camera module contains efficient infrared image processing algorithms including : Temperature compensation non-uniformity correction, Bad/Dead pixel replacement, Column noise removal, Contrast/Edge enhancement algorithms providing stable and low residual non-uniformity infrared image.