• Nuclear Engineering and Technology
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• v.38 no.7
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• pp.665-674
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• 2006

Three-dimensional neutron flux and fluence of Kori Unit 3 were evaluated using the synthesis technique described in Regulatory Guide 1.190 for all reactor geometry. For this purpose DORT neutron transport calculations from Cycle 1 to Cycle 15 were performed using BUGLE-96 cross-section library. The calculated flux and fluence were validated by comparing the calculated reaction rates to the measurement data from the dosimetry sensor set of the $5^{th}$ surveillance capsule withdrawn at the end of cycle 15 of Kori Unit 3. And then the best estimation of the neutron exposures for the reactor vessel beltline region was performed using the least square evaluation. These results can be used in the assessment of the state of embrittlement of Kori Unit 3 pressure vessel.

• The Bulletin of The Korean Astronomical Society
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• v.41 no.1
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• pp.82-82
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• 2016

To find the relationship between solar flares and halo CMEs using stereoscopic observations, we investigate 182 flare-associated halo CMEs among 306 front-side halo CMEs from 2009 to 2013. We have determined the 3D parameters (radial speed and angular width) of these CMEs by applying StereoCAT to multi-spacecraft data (SOHO and STEREO). For this work, we use flare parameters (peak flux and fluence) taken from GOES X-ray flare list and 2D CME parameters (projected speed, apparent angular width, and kinetic energy) taken from CDAW SOHO LASCO CME catalog. Major results from this study are as follows. First, the relationship between flare peak flux (or fluence) and CME speed is almost same for both 2D and 3D cases. Second, there is a possible correlation between flare fluence and CME width, which is more evident in 3D case than 2D one. Third, the flare fluence is well correlated with CME kinetic energy (CC=0.63). Fourth, there is an upper limit of CME kinetic energy for a given flare fluence (or peak flux). For example, a possible CME kinetic energy ranges from 1030.6 to 1033 erg for a given X1.0 class flare. Our results will be discussed in view of the physical mechanism of solar eruptions.

• Nuclear Engineering and Technology
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• v.29 no.2
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• pp.148-157
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• 1997

A new capsule that has a unique structure in which the test environments including neutron flux and fluence, and irradiation temperature can be controlled precisely during irradiation, was conceptually designed. The capsule structure and instrumentation were successfully designed according to the JMTR's standard procedures of capsule design. Based on the target irradiation, the details of the irradiation such as neutron fluence and irradiation temperature ore calculated and the related capsule safety was evaluated. In addition, the effects of design parameters including the changes in inner-capsule configuration, heater capacity, and Helium gas pressure on the specimen temperature were analyzed with a computer program. Through these thermal and strength evaluations, this capsule was proved to be safe during the irradiation in the JMTR.

• Journal of Radiation Industry
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• v.6 no.4
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• pp.323-328
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• 2012

In this study, a facile method to fabricate superhydrophobic surfaces on perfluoroalkoxy (PFA) films using ion implantation was developed. PFA films were implanted at 100 keV with a fluence ranging from $4{\times}10^{16}$ to $7{\times}10^{16}ions\;cm^{-2}$. The surface properties of the implanted films were investigated in terms of their surface morphology, wettability, and chemical composition. As the fluence increased to $6{\times}10^{16}ions\;cm^{-2}$, the surface morphology and surface roughness of the PFA films were dramatically changed. The PFA surface implanted at a fluence of $6{\times}10^{16}ions\;cm^{-2}$ showed a maximum contact angle (CA) of $157.1^{\circ}$, while the control CA of the smooth PFA surface was $103.6^{\circ}$. Thus, the superhydrophobic surface was successfully fabricated by ion implantation.

• Journal of Radiation Protection and Research
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• v.36 no.4
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• pp.200-208
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• 2011

The neutron fluence measurement and evaluation technology is very important for material irradiation test. The most essential technology in this study is the neutron irradiation evaluation method using a fluence monitor. The fluence monitors were fabricated with metal wires of the purity ${\geq}$ 99.9%, whose dimensions were 0.1mm diameter, about 3 mm length, and around 150-200 ${\mu}g$ mass range. Three wire samples (Fe, Ni, Ti) were prepared for one irradiation aluminum capsule. Five capsules were irradiated in the OR5 hole of the HANARO reactor at 30 MW power for about 25 days. After irradiation tests, radiation activities were measured with the high purity germanium (HPGe) detector. The reaction rates were calculated by using the measured radiation activity data, and then neutron fluence were obtained from the reaction rates and the weighted neutron cross section with calculated neutron spectrum at the fluence monitor position.

• Laser Solutions
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• v.14 no.4
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• pp.14-20
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• 2011

The advantage of using lasers for through silicon via (TSV) drilling is that they allow higher flexibility during manufacturing because vacuums, lithography, and masks are not required; furthermore, the lasers can be applied to metal and dielectric layers other than silicon. However, conventional nanosecond lasers have disadvantages including that they can cause heat affection around the target area. In contrast, the use of a picosecond laser enables the precise generation of TSVs with a smaller heat affected zone. In this study, a comparison of the thermal and crystallographic defect around laser-drilled holes when using a picosecond laser beam with varing a fluence and repetition rate was conducted. Notably, the higher fluence and repetition rate picosecond laser process increased the experimentally recast layer, surface debris, and dislocation around the hole better than the high fluence and repetition rate. These findings suggest that even the picosecond laser has a heat accumulation effect under high fluence and short pulse interval conditions. To eliminate these defects under the high speed process, the CDE (chemical downstream etching) process was employed and it can prove the possibility to applicate to the TSV industry.

• Nuclear Engineering and Technology
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• v.54 no.2
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• pp.666-673
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• 2022

The optimization of a transmission type bremsstrahlung conversion target was carried out with Monte Carlo code FLUKA for intense pulsed electron beams with electron energy of several hundred keV for maximum photon fluence. The photon emission intensity from electrons with energy ranging from 300 keV to 1 MeV on tungsten, tantalum and molybdenum targets was calculated with varied target thicknesses. The research revealed that higher target material element number and electron energy leads to increased photon fluence. For a certain target material, the target thickness with maximum photon emission fluence exhibits a linear relationship with the electron energy. With certain electron energy and target material, the thickness of the target plays a dominant role in increasing the transmission photon intensity, with small target thickness the photon flux is largely restricted by low energy loss of electrons for photon generation while thick targets may impose extra absorption for the generated photons. The spatial distribution of bremsstrahlung photon density was analyzed and the optimal target thicknesses for maximum bremsstrahlung photon fluence were derived versus electron energy on three target materials for a quick determination of optimal target design.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2003.11a
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• pp.199-199
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• 2003

During the cleanup of US Department of energy facilities, contaminated materials, toxic and hazardous radionuclides (e.g., Th, Cs, and U) and heavy metals (e.g., Cr, Hg, Pb, and Ni)-laden ultrafine particles are generated. The size of the particles is up to about 200 nm. Understanding of the production of these nanometer size particles is critical in determining the surface cleaning efficiently. (omitted)

• Bulletin of the Korean Chemical Society
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• v.12 no.6
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• pp.652-658
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• 1991

The effect of intermolecular collisions in the infrared multiphoton dissociation (IRMPD) of difluorochloromethane was investigated using He, Ar, and $N_2$ as buffer gases. The reaction probability for IRMPD of difluorochloromethane was measured as a function of laser fluence and the buffer gas pressure under unfocused beam geometry. It was observed that the reaction probability was initially enhanced with the increase of buffer gas pressure up to about 20 torr, but showed a decline at higher pressures. The reaction probability increases monotonically with the laser fluence, but the rate of increase diminishes at higher fluences. An attempt was made to simulate the experimental results by the method of energy grained master equation (EGME). From the parameters that fit the experimental data, the average energy loss per collision, $<{\Delta}E>_d$, was estimated for the He, Ar, and $N_2$ buffer gases.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2002.09a
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• pp.216-218
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• 2002

Fluence and LET spectrum for 290,400 MeV/u $\^$12/C and 400 MeV/u $\^$20/Ne beams have been measured by a $\Delta$E-E counter telescope. Total charge-changing cross sections are deduced from measured fluence. The measured cross sections agree with previous measurements, however, they are disagreement with a model calculation. To dose-averaged LETs, the model calculation can reproduce the measured LETs except for peak LETs at Bragg peak region.