• Journal of the Korean Institute of Telematics and Electronics
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• v.10 no.2
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• pp.16-22
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• 1973

It is described about radiation monitor which can be used for rapidly checking the contamination caused by gamma and beta radiation. and for constantly monitoring such a probable hazardous area. In the circuits used in this device, a detailed analysis on the pulse amplifier and the design formulae of the discriminator circuit is presented. The device is all transistorized and the counting rates are audible through speaker besides being read by meter to the extent of maximum 10 k pps.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.05a
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• pp.778-779
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• 2016

In This paper, We designed the scintillation detector for measuring radiation signals in units of pixels for a radiation source that is distributed in the space. And we carried out a study to design a radiation imaging by the module for obtaining the detection signal. For measuring radiation distribution we configure a radiation detector combining CsI(Tl) scintillator and a photodiode. In addition, its performance was verified via gamma irradiation test.

• Journal of radiological science and technology
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• v.38 no.3
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• pp.253-259
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• 2015

The information of contrast media concentration on target organ is very important to get reduce the side effect and high contrast imaging. We investigated alternation of signal intensity as a function of the modality of Gd-based contrast media on spin echo and ultra short time echo (UTE) of T1 effective pulse sequence at 3T MRI unit. Gadoxetic acid, which is a MRI T1 contrast medium, was used to manufacture an agarose phantom diluted in various molarities, and sterile water and agarose 2% were used as the buffer solution for the dilution. The gold standard T1 calculation was based on coronal single section imaging of the phantom mid-point with 2D Inversion recovery spine-echo pulse sequence MR imaging for testing of phantom accuracy. The 1-2mmol/L and 7mmol/L was shown the maximum signal intensity on spin echo and UTE respectively. We confirm the difference of contrast media concentration which was shown the maximum signal intensity depending on the T1 effective pulse sequence.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.7
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• pp.1777-1783
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• 2014

In this paper, we designed and fabricated a high-speed semiconductor sensor for use in power control devices and analyzed the characteristics with pulsed radiation tests. At first, radiation sensitive circular Si PIN diodes with various diameters(0.1 mm ~5.0 mm) were designed and fabricated using Si epitaxial wafer, which has a $42{\mu}m$ thick intrinsic layer. The reverse leakage current of the diode with a radius of 2 mm at a reverse bias of 30 V was about 20.4 nA. To investigate the characteristic responses of the developed diodes, the pulsed gamma-radiation tests were performed with the intensity of 4.88E8 rad(Si)/sec. From the test results showing that the output currents and the rising speeds have a linear relationship with the area of the sensors, we decided that the optimal condition took place at a 2 mm diameter. Next, for the selected 2 mm diodes, dose rate tests with a range of 2.47E8 rad(Si)/sec to 6.21E8 rad(Si)/sec were performed. From the results, which showed linear characteristics with the radiation intensity, a large amount of photocurrent over 60mA, and a high speed response under 350ns without saturation, we can conclude that the our developed PIN diode can be a good candidate for the sensor of power control devices.

• Journal of the Korean Society of Radiology
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• v.14 no.6
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• pp.791-800
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• 2020

Ultrasonography is widely used to evaluate the function of fetal heart, but due to the subjective nature of the test, there are differences in measurement methods for each examiner, and especially the myocardial performance index has no reference index to date. Therefore, in this study, we wanted to analyze pulse Doppler waveforms of normal fetuses and develop an automatic measurement program to make objective measurements. One hundred and thirty-three pregnant women who visited the hospital for prenatal examinations were studied, myocardial performance index was measured after acquiring a pulse doppler image of the left ventricle. As a result, the early, mid and late pregnancy myocardial performance index, measured by the automatic measurement program conducted in this study, was found to increase as pregnancy continued.

• Journal of the Korean Society of Radiology
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• v.2 no.2
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• pp.31-38
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• 2008

Line scan diffusion weighted imaging (LSDI) pulse sequence for 0.32 T magnetic resonance imaging (MRI) system was developed. In the LSDI pulse sequence, the imaging volume is formed by the intersection of the two perpendicular planes selected by the two slice-selective $\pi$/2-pulse and $\pi$-pulse and two diffusion sensitizing gradients placed on the both side of the refocusing $\pi$-pulse and the standard frequency encoding readout was followed. Since the maximum gradient amplitude for the MR system was 15 mT/m the maximum b value was $301.50s/mm^2$. Using the developed LSDI pulse sequence, the diffusion weighted images for the aqueous NaCl solution phantom and triacylglycerol solution phantom calculated from the line scan diffusion weighted images gives the same results within the standard error range (mean diffusivities = $963.90{\pm}79.83({\times}10^{-6}mm^2/s)$ at 0.32 T, $956.77{\pm}4.12({\times}10^{-6}mm^2/s)$ at 1.5 T) and the LSDI images were insensitive to the magnetic susceptibility difference and chemical shift.

• Journal of IKEEE
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• v.11 no.4
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• pp.257-264
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• 2007

The MM22 microtron has used as a cancer therapy machine from Nov. 1986 to Feb. 2006. This machine was moved and installed to a radiation research center to use as an education and research tool from treatment machine because of aging of MM22 microtron. In this paper, for extracting the electron beam from microtron, operation principle of the microtron, system characteristics of each module, and pulse structures were reviewed. The beam extraction and measurement were performed after measuring pulses of each major module and extraction trials in the beam line. After finishing the movement of MM22 microtron, the 30mA target current in the case of 10 MV X-ray beam was extracted and the beam flatness of radiation distribution was acquired within 3% error ratio after 100 MU was irradiated on X-omatV Film at SSD 100 cm and field size $10{\times}10cm^2$. As a result, the microtron movement and new installation was performed with success.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.5
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• pp.885-892
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• 2017

In this paper, we proposed a novel crowbar circuit for high-speed discharge charge switching to solve discharge charge-time delay of supply voltage in the conventional crowbar circuit. The proposed circuit is designed to increase the charge-speed after high-speed discharge of supply voltage, thereby reducing the time exposed to radiation damage and, the normal operation time of electronic system after passing the pulse radiation. The simulation of the discharge charge-times before the implement of the hardware is conducted using Cadence's pspice tool, and DUT (Device Under Test) board is fabricated in the device level. The comparison measurement of the crowbar circuits is performed on the satellite-electronic device for 24V. As the result, we confirmed the high-speed function of the proposed circuit by improvement of the discharge-speed 96.8% and the charge-speed 27.3% as compared with the conventional circuit.

• Journal of the Korean Society of Radiology
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• v.11 no.3
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• pp.101-108
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• 2017

DC/DC switching power converters are commonly used to generate a regulated DC output voltage with high efficiency. The advanced DC/DC converter uses a PWM-IC with OP-Amp. (Operational Amplifier) to control a MOSFET (metal-oxide semiconductor field effect transistor), which is a switching component, efficiently. In this paper, it is shown that the electrical characteristics of OP-Amp. are affected by radiations of ${\gamma}$ rays using $^{60}Co$ for TID (Total Ionizing Dose) testing and 5 heavy ions for SEL (Single Event Latch-up) testing. TID testing on OP-Amp. is accomplished up to the total dose of 30 krad, and the cross section($cm^2$) versus LET($MeV/mg/cm^2$) in the OP-Amp. operation is evaluated SEL testing after implementation of the controller board.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.1
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• pp.223-228
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• 2017

In this paper, we are proposing an optimal design of wideband pulsed type gamma-ray sensors. These sensors were manufactured based on the design results and after word electrical properties were analyzed. The sensor input parameters were derived on the basis of pulsed gamma-ray spectrum and time-dependent energy rate, and the output current which were derived on the basis of the sensor sensitivity control circuit. Pulsed gamma-ray sensors were designed using the TCAD simulators. The design results show that the optimal Epi layer thickness is 45um with the applied voltage 3.3V and the diameter is 2.0mm. The doping concentrations are as follows : N-type is an Arsenic as $1{\times}10^{19}/cm^3$, P-type is a Boron as $1{\times}10^{19}/cm^3$ and Epi layer is Phosphorus as $3.4{\times}10^{12}/cm^3$. The fabricated sensor was a leakage current, 12pA at voltage -3.3V and fully depleted mode at voltage -5V. A test result of pulsed radiation shows that the sensor gives out the optimal photocurrent.