• Korean Journal of Optics and Photonics
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• v.14 no.6
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• pp.573-577
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• 2003

We report an effect of photon pairs on single-photon detection rates, while Hong-Ou-Handel's two-photon interference experiment is performed with photons produced in noncollinear type-I parametric down-conversion. Photon pairing behavior or spatial bunching is measured and shown to cause a decrease in the single photon counting rate. Such a dip is found to result from the fact that the single-photon timing resolution of photodetectors is much longer compared to the time interval between the two photons incident on the single-photon detector.

• Progress in Superconductivity
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• v.14 no.2
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• pp.96-98
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• 2012

Bias current dependence of a superconducting strip photon detector is studied in the wavelength range of 405 to 1310 nm. The detector is made of an $MgB_2$ meander pattern with the line width of 135 nm and thickness of 10 nm. At 1310 nm, the detection efficiency exponentially decreases as the bias current decreases. While at 405 nm, the detection efficiency almost saturates in the high bias current region. These features suggest that the intrinsic detection efficiency of the $MgB_2$ detector is high at 405 nm.

• Korean Journal of Food Science and Technology
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• v.33 no.2
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• pp.173-177
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• 2001

A study was carried out to establish a detection method for imported sesame and perilla seeds using pulsed photostimulated luminescence (PPSL) whether they have been irradiated or not. Samples were packed in polyethylene bags and irradiated at 1, 5, and 10 kGy with a dose rate of 10 kGy/h. The whole sample of sesame and perilla and the minerals separated from seeds were introduced in the sample chamber and measured PPSL photon counts for 60 and 120 s. The PPSL photon counts of samples increased with increasing irradiation dose and showed a higher correlation coefficients in separated minerals than in sesame and perilla seeds themselves. These results suggest that imported sesame and perilla seeds be possibly detected by both their whole sample and separated minerals by PPSL measurements.

• Korean Journal of Food Science and Technology
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• v.30 no.3
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• pp.498-501
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• 1998

It was determined whether photostimulated luminescence (PSL) is applicable to the detection of post-irradiation of foods by measuring PSL photon counts for unirradiated and irradiated pepper powder, dried herbs, fresh shrimp, potato, soybean, dried fig, chestnut, dried squid, and dried cod. The samples were irradiated with $^{60}Co\;{\gamma}-ray$ source and PSL photon counts were measured for them. The photon counts of unirradiated samples were lower than 2,000 for potatoes and less than 1,000 for the others. The photon counts of the irradiated samples except dried figs (0.5 kGy), chestnuts (0.2 kGy), and dried squid (0.5 kGy) were higher than 1,000, and the photon counts increased with dose. Thus, PSL might be applied to the primary detection of irradiated foods.

• Journal of the Korean Society of Radiology
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• v.10 no.1
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• pp.1-6
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• 2016

Recently, the various digital X-ray imaging devices using CCD and TFT LCD-based flat panel digital X-ray sensor are being used. In particular, a number of studies on photon counting sensor technique have been reported. In this study, the incident X-rays fluence on the photon counting sensor material was measured to estimate photon detection efficiency which is the quantitative performance evaluation factor of photon counting sensor. The result of measuring the photon fluence by using RQA-M2 Radiation beam quality of IEC 61223-1-2 recommendations, the incident photon fluence could be defined as about $4 photons/(0.01mm)^2{\cdot}{\mu}Gy$ within $10{\mu}m$ pin-hole area, and about $50photons/(0.03mm)^2{\cdot}{\mu}Gy$ within $30{\mu}m$ pin-hole area, and about $698photons/(0.1mm)^2{\cdot}{\mu}Gy$ within $100{\mu}m$ pin-hole area. Consequently, with the previously setup of the incident fluence, the measuring of actual photon counting efficiency by observing the output waveform of the photon counting sensor material was considered possible.

• Journal of the Optical Society of Korea
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• v.12 no.1
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• pp.1-6
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• 2008

We report the simple detection method of the small hydrocarbons, methane and ethane, by continuous-wave cavity ring-down spectroscopy near 1.67 ${\mu}m$ using an external cavity diode laser. The absorption lines of methane between 6002.48 $cm^{-1}$ and 6003.37 $cm^{-1}$ and ethane between 5955.65 $cm^{-1}$ and 5956.4 $cm^{-1}$ have been resolved and employed for the gas detection. The largest absorption cross sections were found to be 6.5$\times10^{-20}cm^2$ and 7.4$\times10^{-21}cm^2$ for methane and ethane, respectively, in each spectral range. The minimum detectable absorption limit of our spectrometer was 4.8${\times}10^{-9}cm^{-1}$/$\sqrt{Hz}$, which corresponds to the detection limits of 3 ppb/$\sqrt{Hz}$ and 27 ppb/$\sqrt{Hz}$ for methane and ethane, respectively. The near-IR continuous-wave cavity ring-down spectroscopic detection method of the small hydrocarbons can be applied for medical diagnosis and environmental monitoring as a fast and convenient method.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08a
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• pp.283-285
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• 2007

This paper will discuss the latest results from an advanced array test system, using newly developed sensor technology. A comparison of detection results between old and new generation products will be shown along with a discussion of the advantages of the new, higher signal to noise ratio detector.

• Preventive Nutrition and Food Science
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• v.6 no.3
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• pp.152-157
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• 2001

Accumulated photon counts in immediate measurement after irradiation of marjoram, basil and thyme were shown to be below 625$\pm$162, 577$\pm$178 and 1261$\pm$640 Pc, respectively. The accumulated photon counts increased linearly with increasing irradiation doses up to 5 kGy and slightly increased from 5 kGy to 10 kGy. This trend was similar after storage periods. According to storage conditions, the difference of the accumulated photon counts was net clearly observed. The accumulated photon counts of irradiated spice samples decreased with increasing storage periods. The rate of decrease was higher in 5 and 10 kGy irradiated samples than that in 1 kGy, and in room conditions than that in darkroom conditions. The photon counts of the irradiated spice samples measured for 120 s were higher than those measured for 60 s. The irradiated spice samples showed higher photon counts than those of unirradiated samples in both room and darkroom conditions during all the storage periods. These results indicate that detection of irradiation was still possible after 24 weeks, although the PPSL signal of all spice samples decreased with increasing storage times.

• JSTS:Journal of Semiconductor Technology and Science
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• v.14 no.6
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• pp.789-796
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• 2014

A CMOS photo detection bias quenching circuit is developed to be used with single photon avalanche photodiodes (SPADs) operating in Geiger mode for the detection of weak optical signals. The proposed bias quenching circuits for the performance improvement reduce the circuit size as well as improve the performance of the quenching operation. They are fabricated in a $0.18-{\mu}m$ standard CMOS technology to verify the effectiveness of this technique with the chip area of only $300{\mu}m^2$, which is about 60 % of the previous reported circuit. Two types of proposed circuits with resistive and capacitive load demonstrated improved performance of reduced quenching time. With a commercial APD by HAMAMATSU, the dead time can be adjusted as small as 50 ns.

• Clean Technology
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• v.17 no.3
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• pp.231-237
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• 2011

Two-photon microscopy (TPM) is attracting much attention in biological imaging due to the capability of imaging deep inside the living tissues for a long period of time. For maximum utilization of TPM, it is essential to develop efficient twophoton sensors. Regarding this, many research groups are developing two-photon sensors for specific applications. In this review, we summarize recent results on selected examples of two-photon sensors for intracellular free metal ions in the live cells and tissues to provide a guideline for various imaging applications.