• Journal of Institute of Control, Robotics and Systems
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• v.8 no.2
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• pp.136-141
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• 2002

The electrical characteristics of solid state devices such as BJT(Bipolar Junction Transistor) and MOSFET, etc, are altered by impinging nuclear radiation and temperature in the space environment. This phenomenon is well known and has been studied extensively since the early 1960's when satellites were first being designed and used in the United States. However, the studies and the developments of radiation hardening technologies for the electronic components at the industrial fields in our country has not been popular so far. The worst case design technology in the electrical circuit is required for the appropriate operation of solid state devices in the space environment. In this paper, the interface circuit used in KOMPSAT(Korea Multipurpose Satellite), which is now being operated since the one was launched in 1999, is optimally designed to accomodate the worst case design and radiation effect.

• Journal of the Korean Society of Industry Convergence
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• v.12 no.4
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• pp.179-186
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• 2009

Electronic components in an enclosure have been investigated to prevent undesired thermal problems. The electronic devices, such as ECUs of automotive engines, are operated under the contaminated environments, so that they rely on the passive cooling without any fluid-driving methods. Therefore the radiation heat dissipation plays more important role than the conduction and convection heat transfer. Hence their combined heat dissipation phenomena have been simulated by a numerical model to reveal the effects of supplied heat flux, emissivity of material, geometry of enclosure, charging gas and pressure. The result showed that the radiation had a significant effect on the heat dissipation of module in an enclosure, and some space above the module should be reserved to prevent its thermal problem. In addition, the higher thermal conductivity and pressure of gas in an enclosure could be necessary to improve the thermal dissipation from the electronic devices.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.2287-2290
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• 2003

The electrical characteristics of power devices such as BJT (Bipolar Junction Transistor), and MOSFET (Metal Oxide Field Effect Transistor), etc, are altered due to impinging photon radiation and temperature in the nuclear or the space environment. In this paper, BJT and MOSFET are the two devices subjected to ${\gamma}$ radiation. In the case of BJT, the current gain (${\beta}$) and the collector to Emiter breakdown voltage ($V_{CEO}$) are the two main parameters considered. When it was subjected to ${\gamma}$ rays, the ${\beta}$ decreases as the dose level increases, whereas, $V_{CEO}$ gradually increases as the dose level increases. In the case of MOSFET, the threshold voltage is decreasing as the dose level increases. Here it has been observed the decent rate is an increasing function of the threshold voltage. The on-resistance does not change with respect to the dose. Both the devices recover back the original specification after the annealing is finished. No permanent damage has been occurred.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.33 no.2
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• pp.151-154
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• 2020

Radiation noise due to EMI noise generated by the driving circuits of LED lighting devices in a medical imaging room was reduced by decreasing the noise source in the driving circuits and changing the number of corrections in EMI filters. Noise attenuation and filter changes enabled driving circuits that reduced the electromagnetic waves. Such circuits were efficiently designed by using capacitors and inverters in a given space. Therefore, the malfunction of radiation devices can be minimized by using EMI-reduction filter circuits, and reliable operation of medical devices can be expected by blocking electromagnetic waves.

• The Korean Journal of Nuclear Medicine Technology
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• v.14 no.2
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• pp.65-76
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• 2010

Purpose: he use of PET scanners and the number of patient in Korea have been increased for recent several years dramatically. For this reason, technologists have more possibilities to be exposed to the radiation. The hospitals using PET scanners should make an effort to reduce the radiation exposure dose. The purpose of this study was to evaluate the radiation exposure does when using radiation shielding devices. The evaluation was performed through questionnaire survey and experiment. Materials and Methods: First, the technologists who had experience working in PET center in 2008-2009 were surveyed with questionnaire and TLD Figures, personal opinion of utilization of radiation shielding devices are analyzed. Second, we measured the shielding rate of shielding devices which have been using in PET study procedures. We divided the procedures into four steps; distribution, moving, injection of $^{18}F$-FDG and patient setup. Results: First, the results of this survey, using of L-block+Syringe shield, L-block, Syringe shield, No shield during the injection, were each 58.5%, 20%, 9%, 12.3%. The TLD values according to utilization of radiation shield, using both L-block+Syringe Shield and L-block showed the lower TLD values, and Syringe shield only or No shield showed the higher TLD values. Second, the results of experiments according to PET study procedures measured the shielding rates as follows. The shielding rates during the distribution using L-block, L-block+Apron shield were measured 97.4%, 97.7%. The shielding rates during the $^{18}F$-FDG delivery to the injection room using mobile Syringe shield, Syringe holder, Syringe shield carrier were each 81.7%, 98.9%, 99.7%. The shielding rates during the injection using Syringe shield, L-block, L-block+Syringe shield were measured each 51.9%, 98.3%, 98.7%. The shielding rates of Apron were measured in each 30, 60, 90, 120, 150 cm distance. The measurement were each 16.9%, 14.2%, 16.6%, 17.1%, 18.1%, 18.6%. Conclusion: The most effective method for radiation shielding is to using L-block during the $^{18}F$-FDG distribution and Syringe shield carrier during in moving $^{18}F$-FDG. For the $^{18}F$-FDG injection, L-block+Syringe shield have to be used. The shielding effect of Apron has shown average 16.4%. According to the survey of questionnaire, the operators recognized well risk of the radiation exposure but, tended ignore in working. The radiation dose according to recognition of radiation exposure risk was not relevant. but radiation dose according to utilization of radiation shield lower the more use it. The main reason of no use of shielding devices is cumbersome, 55% of the respondents answered. I'm sure, by use of radiation shield in all PET procedure, radiation exposure will be reduced considerably.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.05a
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• pp.1023-1026
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• 2013

The electronic equipment which was exposed to high level pulsed radiation is damaged as Upset, Latchup, and Burnout. Those damages has come from the instantaneous photocurrent from electron-hole pairs generated in itself. Such damages appeared as losses of power in military weapon system or of blackout in aerospace equipment and eventually caused in gross loss of national. In this paper, we have implemented a RDC(Radiation detection and control module) as part of the radiation protection technology of the electronic equipment or devices from the pulsed gamma radiation. The RDC which is composed of pulsed gamma-ray detection sensor, signal processors, and pulse generator is designed to protect the important electronic circuits from the pulse radiation. To verify the functionality of the RDC, LM118s which had damaged by the pulse radiation were tested. The test results showed that the test sample applied with a RDC was worked well in spite of the irradiation of the same pulse radiation. Through the experiments we could confirm that the radiation protection technology implemented with RDC had the functionality of radiation protection to the electronic devices.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.16 no.4
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• pp.375-382
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• 1987

Accurate solar radiation data are fundamental to the design of HVAC systems and solar driven devices. Unfortunately, the total radiation data on a horizontal surface has been only reported by meteorological office. Consequently, there is interest in development of model to estimate the solar radiation data. Based on the statistically estimated TAC data which were obtained from measured hourly values collected over a period of ten years at Seoul, the solar radiation model was determined. Atmospheric transmittance for this model was presented in the form of polynominal.

• The Journal of Korean Society for Radiation Therapy
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• v.2 no.1
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• pp.81-85
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• 1987

It has been evident since 1972 that computed tomography(CT) can play an important role in treatment and managment of the cancer patients as four steps; diagnosis, satging Treatment and follow-up. In this paper, we intended to investigate the availability of CT scan and treatment planning computer in 700 cancer patients who have undergone radiation therapy at the division of radiation therapy, Kangnam St. Mary's Hospital, Catholic Medical College between Mar. 1983 and Dec. 1985. The result were as follow; 1. Of 700 irradiated cancer patients, 342 patients ($48.9\%$) were performed CT scan prior to radiation therapy. 2. The distribution of lesions in 342 patients having CT scans was like this; CNS (83 of 104 patients, $79.8\%$), abdomen (44 of 76 patients, $57.9\%$), pelvis (100 of 188 patients, $53.2\%$) etc. in order. 3. The treatment planning computer were used in 280 cancer patients ($40\%$). 4. Of the 280 cancer patients using treatment planning computer, 167 patients ($59.6\%$) applied diagnostic CT scan and remaining 113 patients ($40.4\%$) were made body contour to be used for radiation therapy planning by the treatment planning computer. Authors also made some magnification devices used for small multiformat CT images to magnify into life size, consisting of overhead projector (3M) I.V. stand and mirror. These enabled us to make less errors in tracing the small-sized CT images during input of the anatomical data into the treatment planning computer.

• Electronics and Telecommunications Trends
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• v.5 no.1
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• pp.55-70
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• 1990

SIMOX SOI is known to be one of the most useful technologies for fabrications of new generation ULSI devices. This paper describes the current status of SIMOX SOI technology for ULSI applications. The SIMOX wafer is vertically composed of buried oxide layer and silicon epitaxial layer on top of the silicon substrate. The buried oxide layer is used for the vertical isolation of devices The oxide layer is formed by high energy ion implantation of high dose oxygen into the silicon wafer, followed by high temperature annealing. SIMOX-based CMOS fabrication is transparent to the conventional IC processing steps without well formation. Furthermore, thin film CMOX/SIMOX can overcome the technological limitations which encountered in submicron bulk-based CMOS devices, i.e., soft-error rate, subthreshold slope, threshold voltage roll-off, and hot electron degradation can be improved. SIMOX-based bipolar devices are expected to have high density which comparable to the CMOX circuits. Radiation hardness properties of SIMOX SOI extend its application fields to space and military devices, since military ICs should be operational in radiation-hardened and harsh environments. The cost of SIMOX wafer preparation is high at present, but it is expected to reduce as volume increases. Recent studies about SIMOX SOI technology have demonstrated that the performance of the SIMOX-based submicron devices is superior to the circuits using the bulk silicon.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2004.11a
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• pp.153-156
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• 2004

Korea Food and Drug Administration(KFDA) has peformed the calibration of therapy level dosimeters for Co-60 radiation since 1979. The reference standard ionization chamber has been calibrated at BIPM in France. The uncertainty on the KFDA calibration coefficients is 0.9 %(k=2) for air kerma and absorbed dose to water. Since 1999 a national quality audit program for ensuring dosimetry accuracy in Korea radiotherapy centers has been performed by the KFDA. The uncertainty associated with the determination of the absorbed dose to water from the TLD readings for high energy x-ray is 1.6 %(k=1). The correction factors for energy, non-linearity dose response, and TLD holder are used in the dose determination. Agreement between the user stated dose and KFDA measured dose within ${\pm}$ 5 % is considered acceptable. KFDA TLD postal dose quality audit program was peformed for 71 beam qualities of 53 domestic radiotherapy centers in 2003. The results for quality assurance showed that 63 out of 71 beam qualifies (89 %) satisfied the acceptance limit. The second audit was carried out for the centers outside the limit and ail of them have been corrected.