• Proceedings of the Korean Nuclear Society Conference
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• 2004.05a
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• pp.401-401
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• 2004

• Bulletin of the Korean Chemical Society
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• v.31 no.11
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• pp.3366-3370
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• 2010

The specific rates of solvolysis of t-butyl fluoroformate (1) have been measured at $40.0^{\circ}C$ in 21 pure and binary solvents. These give a satisfactory correlation over the full range of solvents when the extended Grunwald-Winstein equation, with incorporation of the solvent nucleophilicity and the solvent ionizing power, is applied. The actual values are very similar to those obtained in earlier studies of the solvolyses of isopropyl chloroformate and ethyl chlorothioformate in the more ionizing and least nucleophilic solvents, which are believed to proceed by an ionization pathway. The small negative values for the entropies of activation are consistent with the ionization nature of the proposed rate-determining step. These observations are also compared with those previously reported for the corresponding primary and secondary alkyl haloformate esters.

• Publications of The Korean Astronomical Society
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• v.22 no.4
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• pp.97-101
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• 2007

We are often faced with the task of having to estimate the hydrogen and helium ionizing luminosities of massive stars in the study of H II regions and the warm ionized medium (WIM). Using the results of the most complete compilation of stellar parameters (the effective temperature, stellar radius and surface gravity) and the latest Kurucz stellar atmosphere models, we calculate the ionizing photon luminosities in the $H^0\;and\;He^0$ continua from O3 to B5 stars. We compared the theoretical Lyman-continuum luminosity with the observationally inferred luminosity of the H II region around ${\alpha}$ Vir, and found that the theoretical value is higher than the observed value in contrast to the eariler result.

• Journal of Radiation Protection and Research
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• v.13 no.1
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• pp.42-54
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• 1988

Overall reviews of papers presented at the seventh IRPA International Congress (Aprill 10-17, 1988) held in Sydney, Australia have been done in order to grasp the trends of radiation research. In this report, the changing and increasing matters in the field of ionizing radiation safety as well as non-ionizing radiation application are introduced to the KARP. In addition, a research paper, 'Emission Rate Measurement of a Cf-252 Neutron Source by Manganous Sulfate Bath Method', presented at the IRPA 7 Poster Session is followed.

• Journal of Radiation Industry
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• v.8 no.2
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• pp.71-76
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• 2014

Endocrine disrupting chemicals (EDCs) and potential EDCs are mostly man-made, found in various materials such as pesticides, additives or contaminants in food, and personal care products. The high energy ionizing radiation has the ability to remove the EDCs with a very high degree of reliability and in a clean and efficient manner. The ionizing radiation interacts with EDCs both directly and indirectly. Direct interaction takes place with EDCs and the structure of EDCs is destroyed or changed. During indirect interaction, radiolysis products of water result in the formation of highly reactive intermediates which then react with the target molecules, culminating in structural changes. To confirm the radiation reduction of EDCs in industrial sludge, a pilot scale experiment up to 50 kGy of electron beam (EB) was conducted with samples from the textile dyeing industries. The experimental result showed the over 90% of reduction of Nonylphenol (NP) and Di(2-ethylhexyl) phthalate (DEHP) at around 10 kGy of absorbed doses.

• Food Science and Industry
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• v.53 no.3
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• pp.264-276
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• 2020

Ionizing radiation is one of the efficient non-thermal pasteurization methods. The US Food and Drug Administration (FDA) allows the use of ionizing radiation to a dose up to 10 kGy for controlling foodborne pathogens and extending the self-life of foods. Recently X-rays, generated on absorption of high energy electrons in an appropriate metal target, have been used commercially for sterilization purposes. X-rays have the advantages of higher penetration power than E-beams and absence of harmful radioactive sources, such as Cobalt-60 or Cesium-137 associated with gamma-rays. That is why it has continued to receive attention as an attractive alternative to gamma-ray or E-beam irradiation. In this article, the potential of X-ray irradiation for controlling foodborne pathogens in various food products and necessary pre-requisite knowledge for the introduction of X-ray irradiation to the Korean food industry will be provided.

• Journal of Semiconductor Engineering
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• v.1 no.3
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• pp.81-87
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• 2020

An instrumentation amplifier (IA) and an analog-to-digital converter (ADC) are essential circuit blocks for accurate and robust sensor readout systems. This paper introduces recent advances in radiation-hardening by design (RHBD) techniques applied for the sensor readout integrated circuits (IC), e.g., the three-op-amp IA and the successive-approximation register (SAR) ADC, operating against total ionizing dose (TID) and singe event effect (SEE) in harsh radiation environments. The radiation-hardened IA utilized TID monitoring and adaptive reference control to compensate for transistor parameter variations due to radiation effects. The radiation-hardened SAR ADC adopts delay-based double-feedback flip-flops to prevent soft errors which flips the data bits. Radiation-hardened IA and ADC were verified through compact model simulation, and fabricated CMOS chips were measured in radiation facilities to confirm their radiation tolerance.

• Nuclear Engineering and Technology
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• v.55 no.5
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• pp.1671-1676
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• 2023

The influence of adding iodine as a contrast substance to elevate radiation in a tumor is studied using simulation techniques of Monte-Carlo. The study is carried on a brain cancer by adopting an unsophisticated head phantom. The ionizing radiation source is an external beam of x-rays with energy range of a few tens of keV. The expected radiation dose increment due to adding the iodine is investigated by comparing the radiation in the tumor after and before adding the iodine and calculating the ratio between the two doses. Several concentrations of the contrast substance are used to quantify its impact. The change of the dose increment with the source energy is also examined. It is found that the radiation elevation in the tumor tends to saturate with increasing the iodine concentration, and for the studied domain of energies (30 keV-100 keV), the radiation dose enhancement factors (RDEF) for the different iodine concentrations (1%-9%) show peaked curves, with the peak occurring between 60 keV and 70 keV. For the highest concentration studied, 9%, the peak value is almost 7.

• Proceedings of the Korean Nuclear Society Conference
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• 2001.05a
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• pp.399.2-399
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• 2001

• Proceedings of the Korean Nuclear Society Conference
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• 2001.05a
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• pp.454.1-454
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• 2001