• Proceedings of the IEEK Conference
• /
• 2000.06e
• /
• pp.106-109
• /
• 2000

The diode characteristics for therapy radiation sensor have been studied by irradiating therapy radiation from the MM22 microtron accelerator. Signal processing has been performed in the pulse mode which can process the signal fast. We have designed integrator, peak detector and synchronization circuit to detect diode signal in the pulse mode for implementation of portal image. We also read the diode signal by A/D board and displayed the peak value with LabView program. Because the quality of portal image obtained by film in the case of therapy radiation is much worse than that of diagnostic film, Digital radiography system by rectifier diode detector was suggested for portal Image.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.13 no.6
• /
• pp.507-513
• /
• 2002

In this paper, the receiver using Heterodyne type is designed and implemented for a pulse radar at 9.4 GHz. The If amplifier, which occupies a significant size in a Heterodyne receiver for pulse radars, can be removed. Furthermore, by using detector logarithmic video amplifier in baseband, the receiver has a small size and it's characteristic shows a high dynamic range and sensitivity. From the results of measurements, the minimum receiver power of -70 dBm and selectivity of 55 dB are obtained.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2015.10a
• /
• pp.578-579
• /
• 2015

Transmission and reflectance are two non-invasive techniques to perform pulse oximetry. This paper presents a design of reflectance-based pulse oximetry for watch-type wearable device, in which sensor and detector are located on the same surface of the body part. The basic principle of a pulse oximeter is based on the measurement of the red and infrared (IR) light absorption. Oxygenated blood has significant differences of light absorption characteristics than deoxygenated blood under red (660 nm) and infrared (940 nm) wavelength. Infrared is absorbed more by oxygenated hemoglobin than red. So the hardware implementation is included placing of the two LEDs (red and IR) with single photo-detector in the middle on the patient's wrist to get the corresponding pulsatile signals which are used to estimate the $SpO_2$.

• The Transactions of the Korean Institute of Electrical Engineers C
• /
• v.54 no.11
• /
• pp.508-514
• /
• 2005

In this paper, it was investigated the characteristics of PD(partial discharge) pulse shapes in oil and the possibility of TF(Time-Frequency) analysis for the discrimination of air corona in on-site PD measurement of oil transformers. For the purpose, single and multiple discharges combined with oil discharges and air corona were generated and measured by use of artificial models through the HFPD pulse detector and the oscilloscope. PD pulse shapes were different according to the type of defects, especially including air corona- pulses. Also, through the TF analysis, data clusters could be classified each other in the TF Map, even in the case of multiple discharges. Therefore, it is known that TF analysis could be aprlied for the improvement of on-site PD measurement in oil transformers.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
• /
• 2002.02a
• /
• pp.197-201
• /
• 2002

A free piston and free displacer (FPFD) Stirling cryocooler and inertance pulse tube cryocooler for the cooling infrared detector and cryosensor are currently under development at Korea Institute of Machinery ＆ Materials. The pulse tube cryocooler, which has no moving parts at its cold section, is attractive for obtaining higher reliability, simpler construction and lower vibration than in any other small cryocoolers. In recent years, pulse tube cryocoolers have experienced a rapid development with the aim to eventually replace Stirling and Gifford-McMahon cryocoolers in various applications. In this study, operating characteristics of the conventional linear Stirling cryocooler was investigated by experiment. And, inertance pulse tube cryocooler with the commercial linear compressor(Leybold Polar) was designed, manufactured, and tested by the variations of the operating frequency, charging pressure and input power.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
• /
• 1989.10a
• /
• pp.65-70
• /
• 1989

This paper presents resarch results on the use of a corona detector and a pulse counter in order to diagnose for oil transformers. Using these experimental apparatus, tests were carried out on a typical transformer oil containing different carbonized paper and various moisture contents to measure the picocoulomb val-ues and pulse count. Through the result of this study it was found that the picocoulomb values and pulse count of corona were depended on the getting stained in transformer oil. The amplitude of the partial discharge amount and the number of pulse were decreased up to 70 [。c] and then was increased as the oil temperature goes up. It was concluded that the determinati-on level for diagnosis of oil transform-er was taken into account the temperatu-er of transformer oil, The use of pulse counter method, which have been taken the same property of voltage and temperature variation for the corona measurement mothod, considera-bly increase insulator avilability.

• Progress in Superconductivity
• /
• v.14 no.2
• /
• pp.87-91
• /
• 2012

Metallic magnetic calorimeters (MMCs) are one of the most competitive low temperature detector (LTD) readout sensors. They have the advantages of high time resolution, no heat dissipation, and a wide range of operating temperature. We apply MMCs to our neutrinoless double beta decay ($0v{\beta}{\beta}$) search experiment. A $CaMoO_4$ crystal was employed as both a source of $0v{\beta}{\beta}$ and an energy absorber. The crystal was thermally connected to a MMC sensor. We set a simple thermal model for this detector and measured pulse shapes are compared with a numerical solution of the thermal model.

• Journal of the Korea Society of Computer and Information
• /
• v.20 no.7
• /
• pp.57-64
• /
• 2015

In this paper, we propose a design of microwave motion detector using X-band doppler radar sensor to minimize the power consumption. To minimize the power consumption and implement battery operated system, pulse input with 2 KHz, 4% duty cycle is exerted on the doppler radar sensor. In order to simplify the process of working with ATmega2560 microcontroller unit, Arduino compatible board is designed and implemented. Arduino is open source hardware and many library software is published as open source tools. Smartphone app is also proposed and designed as a real-time user interface of the motion detector. The SQLite database on the Android mobile operating system is used for recording raw data of motion detection for post-processing job, such as fast Fourier transform (FFT). Bluetooth interface module is implemented on the motion detection board as a wireless communication interface to the smartphone. The speed of human movement is identified by post-processing FFT.

• Proceedings of the KSR Conference
• /
• 2005.11a
• /
• pp.777-782
• /
• 2005

In this paper, we designed and fabricated a partial discharge (PD) detector to diagnose the soundness of CNCV cables by analyzing PD pulses and to predict discharge locations. The PD detector is consisted of a coupling network with a discharge free capacitor and a detection impedance, a voltage follower and a low noise amplifier. Lower cut-off frequency of the detector is adjusted at 175kHz to block AC voltage and to pass discharge pulse only. The discharge location could be obtained by the time of arrival method using travelling wave propagation theory. In a laboratory test on an eighty meter CV cable, we could position the discharge location within a two meter error.

• Journal of Radiation Protection and Research
• /
• v.41 no.3
• /
• pp.185-190
• /
• 2016

Background: In order to measure neutron energy spectra, the conventional Bonner Sphere Spectrometers (BSS) are widely used. In this spectrometer, several measurements with different size Bonner spheres are required. Operators should, therefore, place these spheres in several times to a measurement point where radiation dose might be relatively high. In order to reduce this effort, novel neutron energy spectrometer using an onion-like single Bonner sphere was proposed in our group. This Bonner sphere has multiple sensitive spherical shell layers in the single sphere. In this spectrometer, a band-shaped thermal neutron detection medium, which consists of a LiF-ZnS mixed powder scintillator sheet and a wavelength-shifting (WLS) fiber readout, was looped to each sphere at equal angular intervals. Amount of LiF neutron converter is reduced near polar region, where the band-shaped detectors are concentrated, in order to uniform the directional sensitivity. The LiF-ZnS mixed powder has an advantage of extremely high light yield. However, since it is opaque, scintillation photons cannot be collect uniformly. This type of detector shows no characteristic shape in the pulse height spectrum. Subsequently, it is difficult to set the pulse height discrimination level. This issue causes sensitivity fluctuation due to gain instability of photodetectors and/or electric modules. Materials and Methods: In order to solve this problem, we propose to replace the LiF-ZnS mixed powder into a flexible and Transparent RUbber SheeT type $LiCaAlF_6$ (TRUST LiCAF) scintillator. TRUST LiCAF scintillator can show a peak shape corresponding to neutron absorption events in the pulse height spectrum. Results and Discussion: We fabricated the prototype detector with five sensitive layers using TRUST LiCAF scintillator and conducted basic experiments to evaluate the directional uniformity of the sensitivity. Conclusion: The fabricated detector shows excellent directional uniformity of the neutron sensitivity.