• 전기의세계
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• v.22 no.1
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• pp.35-41
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• 1973

An automatic point traffic control method is recommended for more idealistic traffic flow over coarse road netowrks. The automatic control apparatus recommended, consists of a transceiver, amplifier, digital-to-analog converter, signal light controller for emergency and steady state, and digital counter as monitor. The transmitter sends a signal to the target vy means of Microwave-FM-CW and a diode detector picks up the echo signal. Thus the operation of the entire system will be carried out through an open loop state. Some factors necessary for an ideal detector system are rapid response, longevity and stability. An analytical method of the Doppler effect substitutes the conventional frequency deviation into the amplitude of detector output. The changing rate of amplitude is proportional to the voltage of the detector output. Some induced formula from Maxwell's radiation field theory ensures this new method, and, new method, and proves the fact with an experimental data presentation. Stability depends upon Klystron as an oscillator and a diode as a detector. the transceiver installation affects on the response and sensitivity of the system. In accordance with the detector output, several targets are easily classified by amplitudes on the scope. The traffic flow, i.e., target movement which is analyzed by the amplitude method, is shown through the scope and indicates it on the digital counter. The best efficiency for the amplitude analysis can be attained through use of an antenna having the highest sensitivity.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.16 no.1
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• pp.9-18
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• 2010

For screening test of the non-volatile compounds which migrate from food packaging materials into foodstuffs, the traditional high performance liquid chromatography (HPLC) systems suffer from the lack of universal detector with high sensitivity and universality and high efficiency HPLC separation column which provides complete separation of complex mixtures into all individual substances. In this work, the use possibility of online two-dimensional liquid chromatography (2D-LC) system coupled with a charged aerosol detector (CAD), a universal detector, was reviewed. 2D-LC system permits to improve peak capacity and resolving power for complex mixtures. Charged aerosol detector (CAD) offers a new feasibility for detection of any non-volatile compounds with high sensitivity and constant response factor in a calibration range. The combination of size exclusion chromatography (SEC) and normal phase HPLC (NP-HPLC) is most frequently used for the separation of the natural and synthetic polymers which are mainly used as raw materials for the manufacture of food packaging materials. However, there is no commercial software available for data acquisition and handling and therefore the quantification in 2D-LC analysis is still rare.

• The Journal of the Korea Contents Association
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• v.19 no.4
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• pp.368-380
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• 2019

This study proposes a method to evaluate the performance of a detector by analyzing the dynamic step wedge and histogram according to the change of the tube voltage and sensitivity when using the Automatic Exposure Control (AEC). The performance of a detector was evaluated by measuring X-ray quality, Entrance Surface Dose (ESD), tube current, dynamic range corresponding to detector sensitivities of S200, S400, S800, S1000 per tube voltage of 60, 70, 81, 90 kVp. As a results, all of the qualities satisfied the acceptance criteria, and the Entrance Surface Dose and tube current were decreased stage by stage as sensitivity was set higher. In the dynamic step wedge, the observable dynamic range has also increased as tube voltage became higher. The histogram showed the quantization separation phenomena as the tube voltage was set higher. The higher the sensitivity, the more the underflow and overflow occurred in which the amount of information on both ends of the histogram was lost. In conclusion, the deterioration in the performance of the detector was found to be insufficient to realize the change of the tube voltage and sensitivity when using the Automatic Exposure Control, and it is useful to use dynamic step wedge and histogram in evaluating detector performance evaluation.

• Journal of the Korean Society of Radiology
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• v.18 no.2
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• pp.65-71
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• 2024

To achieve high resolution and sensitivity of positron emission tomography (PET) for small animals, the detector is constructed using very thin and long scintillation pixels. Due to the structure of these scintillation pixels, spatial resolution deterioration occurs outside the system's field of view. To solve this problem, we designed a detector that could improve spatial resolution by measuring the interaction depth and improve sensitivity by using a quasi-block scintillator. A quasi-block scintillator size of 12.6 mm x 12.6 mm x 3 mm was arranged in four layers, and optical sensors were placed on all sides to collect light generated by the interaction between gamma rays and the scintillator. DETECT2000 simulation was performed to evaluate the performance of the designed detector. Flood images were acquired by generating gamma-ray events at 1 mm intervals from 1.3 mm to 11.3 mm within the scintillator of each layer. The spatial resolution and peak-to-peak distance for each location were measured in an 11 x 11 array of flood images. The average measured spatial resolution was 0.25 mm, and the average distance between peaks was 1.0 mm. Through this, it was confirmed that all locations were separated from each other. In addition, because the light signals of all layers were measured separately from each other, the layer of the scintillator that interacted with the gamma rays could be completely separated. When the designed detector is used as a detector in a PET system for small animals, it is considered that excellent spatial resolution and sensitivity can be achieved and image quality can be improved.

• Journal of Radiation Protection and Research
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• v.43 no.4
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• pp.154-159
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• 2018

Background: To prevent small leakage accidents, a real-time and direct detection system for small leaks with a detection limit below that of existing systems, e.g. $0.5gpm{\cdot}hr^{-1}$, is required. In this study, a small-size beta detector, which can be installed inside the reactor containment (CT) building and detect small leaks directly, was suggested and its feasibility was evaluated using MCNPX simulation. Materials and Methods: A target nuclide was selected through analysis of radiation from radionuclides in the reactor coolant system (RCS) and the spectrum was obtained via a silicon detector simulated in MCNPX. A window was designed to reduce the background signal caused by other nuclides. The sensitivity of the detector was also estimated, and its shielding designed for installation inside the reactor CT. Results and Discussion: The beta and gamma spectrum of the silicon detector showed a negligible gamma signal but it also contained an undesired peak at 0.22 MeV due to other nuclides, not the $^{16}N$ target nuclide. Window to remove the peak was derived as 0.4 mm for beryllium. The sensitivity of silicon beta detector with a beryllium window of 1.7 mm thickness was derived as $5.172{\times}10^{-6}{\mu}Ci{\cdot}cc^{-1}$. In addition, the specification of the shielding was evaluated through simulations, and the results showed that the integrity of the silicon detector can be maintained with lead shielding of 3 cm (<15 kg). This is a very small amount compared to the specifications of the lead shielding (600 kg) required for installation of $^{16}N$ gamma detector in inside reactor CT, it was determined that beta detector would have a distinct advantage in terms of miniaturization. Conclusion: The feasibility of the beta detector was evaluated for installation inside the reactor CT to detect small leaks below $0.5gpm{\cdot}hr^{-1}$. In future, the design will be optimized on specific data.

• Journal of Sensor Science and Technology
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• v.25 no.3
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• pp.229-234
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• 2016

Self-powered neutron detector (SPND) is being widely used to monitor the reactor core of the nuclear power plants. The SPND contains a neutron-sensitive metallic emitter surrounded by a ceramic insulator. Currently, the vanadium (V) SPND has been being developed to be used in OPR1000 nuclear power plants. Some Monte Carlo simulations were accomplished to calculate the initial sensitivity of vanadium emitter material and alumina insulator with a cylindrical geometry. An MCNP code was used to simulate some factors (neutron self-shielding factor and beta escape probability from the emitter) and space charge effect of an insulator necessary to calculate the sensitivity of vanadium detector. The simulation results were compared with some theoretical and experimental values. The method presented here can be used to analyze the optimum design of the vanadium SPND and contribute to the development of TMI (Top-mount In-core Instrumentation) which might be used in the SMART and SMR.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.45 no.3
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• pp.335-340
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• 1996

The item and structure of current detector depends on the current in conductors. The Hall current detector of these detectors is to use the variation of Hall voltage to conductor's current and it is very difficult for the conventional type to detect small current. In this paper we study experimented-method that detect AC current by using the magnetic modulation method the current, 0[mA]~100[mA]. The experiments results in 5 percent against the conventional, 20 percent in linear error, 0.12[.DELTA.mV/.DELTA.mA] to conventional type, 50[.DELTA.mV/.DELTA.mA] in sensitivity. (author). 7 refs., 15 figs.

• Journal of Sensor Science and Technology
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• v.26 no.3
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• pp.149-154
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• 2017

Detection of rain is one of the essential weather factors that are monitored by automatic weather stations in Korea. In this work, we studied the operation standards required for impedance-based rain detectors in terms of surface temperature and sensitivity, in an effort to establish a qualification procedure for rain detectors. The surface temperature of rain detectors was measured at varying air temperatures from $-30^{\circ}C$ to $20^{\circ}C$, considering the hypothetical presence and absence of rain/snow. In addition, the sensitivity of rain detectors was studied generating artificial raindrops of regular size. The sensitivity was evaluated in terms of the critical number of droplets that triggers the activation of the rain detector. We found that the sensitivity is affected by stationary, horizontal, and vertical droplet deposition methods. The critical number of droplets for the stationary deposition is higher than that for both horizontal and vertical depositions, which provides the maximum limit of droplets required to activate the detector. Based on our experiments considering surface temperature measurements and sensitivity tests, we suggest a revised version of surface temperature and sensitivity requirements for the qualification of impedance-based rain detectors.

• Journal of the Korean Society of Radiology
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• v.13 no.2
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• pp.313-318
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• 2019

To improve the sensitivity, a detector using a block scintillator was developed. In the pixelated scintillator, a reflector is located between pixels to move the light generated from the scintillator to the photosensor as much as possible, and sensitivity loss occurs in the reflector portion. In order to improve the sensitivity and to have the characteristics of the pixelated scintillator, the block scintillator was processed into a scintillator in pixel form through three-dimensional laser engraving. The energy spectra and energy resolution of each pixel were measured, and sensitivity analysis of block and pixel scintillator was performed through GATE simulation. The measured global energy resolution was 20.7%, and the sensitivity was 18.5% higher than that of the pixel scintillator. When this detector is applied to imaging devices such as gamma camera and positron emission tomography, it will be possible to shorten the imaging time and reduce the dose of patient by using less radiation source.

• Bulletin of the Korean Chemical Society
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• v.26 no.12
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• pp.1991-1995
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• 2005

Sensitivity factors of elements by a glow discharge mass spectrometry (GD-MS) were intensively investigated and compared with a laser ablation inductively coupled plasma-mass spectrometry (ICP-MS). In case of copper matrix, the sensitivity factor by GD-MS generally decreases with the increase of the mass number of element. The details are a little different between each data measured by Faraday and multiplier detectors. The factor by a multiplier detector drastically decreases with the mass increase in the region of low mass as in Faraday detector’s case, but slowly in the high mass region. On the contrast, the sensitivity factor of solution standard by a conventional ICP-MS slowly increases with the increase of elemental mass number even though there are some exceptions such as gold and also the sensitivity factor by a laser ablation ICP MS generally increases with mass number of element in the specimen of glass type. In case of steel matrix, any definite trends could not be shown in the relationship between the GD-MS’s sensitivity factor and elemental mass.