• Journal of Radiation Protection and Research
• /
• v.39 no.4
• /
• pp.199-205
• /
• 2014

In the field of neutron detections, $^3He$ gas, the so-called "the gold standard," is the most widely used material for neutron detections because of its high efficiency in neutron capturing. However, from variable causes since early 2009, $^3He$ is being depleted, which has maintained an upward pressure on its cost. For this reason, the demands for $^3He$ replacements are rising sharply. Research into neutron converting materials, which has not been used well due to a neutron detection efficiency lower than the efficiency of $^3He$, although it can be chosen for use in a neutron detector, has been highlighted again. $^{10}B$, which is one of the $^3He$ replacements, such as $BF_3$, $^6Li$, $^{10}B$, $Gd_2O_2S$, is being researched by various detector development groups owing to a number of advantages such as easy gamma-ray discrimination, non-toxicity, low cost, etc. One of the possible techniques for the detection is an indirect neutron detection method measuring secondary radiation generated by interactions between neutrons and $^{10}B$. Because of the mean free path of alpha particle from interactions that are very short in a solid material, the thickness of $^{10}B$ should be thin. Therefore, to increase the neutron detection efficiency, it is important to make a $^{10}B$ thin film. In this study, we fabricated a $^{10}B$ thin film that is about 60 um in thickness for neutron detection using well-known technology for the manufacturing of a thin electrode for use in lithium ion batteries. In addition, by performing simple physical tests on the conductivity, dispersion, adhesion, and flexibility, we confirmed that the physical characteristics of the fabricated $^{10}B$ thin film are good. Using the fabricated $^{10}B$ thin film, we made a proportional counter for neutron monitoring and measured the neutron pulse height spectrum at a neutron facility at KAERI. Furthermore, we calculated using the Monte Carlo simulation the change of neutron detection efficiency according to the number of thin film layers. In conclusion, we suggest a fabrication method of a $^{10}B$ thin film using the technology used in making a thin electrode of lithium ion batteries and made the $^{10}B$ thin film for neutron detection using suggested method.

• Progress in Medical Physics
• /
• v.23 no.2
• /
• pp.71-80
• /
• 2012

In order to verify exact dose distributions in the state-of-the-art radiation techniques, a newly designed three-dimensional dosimeter and technique has been took strongly into consideration. The main purpose of our study is to verify the optimized parameters of polymer gel as a real volumetric dosimeter in terms of the various study of MRI. We prepared a gel dosimeter by combing 8% of gelatin, 8% of MAA, and 10 mM of THPC. We used a Co-60 gamma-ray teletherapy unit and delivered doses of 0, 2, 4, 6, 8, 10, 12, and 14 Gy to each polymer gel with a solid phantom. We used a fast spin-echo pulse to acquire the characterized T2 time of MRI. The signal noise ratio (SNR) of the head & neck coil was a relatively lower sensitivity than the body coil; therefore the dose uncertainty of head & neck coil would be lower than body coil's. But the dose uncertainty and resolution of the head & neck coil were superior to the body coil in this study. The TR time between 1,500 ms and 2,000 ms showed no significant difference in the dose resolution, but TR of 1,500 ms showed less dose uncertainty. For the slice thickness of 2.5 mm, less dose uncertainty of TE times was at 4 Gy, as well, it was the lowest result over 4 Gy at TE of 12 ms. The dose uncertainty was not critical up to 6 Gy, but the best dose resolution was obtained at 20 ms up to 8 Gy. The dose resolution shows the lowest value was over 20 ms and was an excellent result in the number of excitation (NEX) of three. The NEX of two was the highest dose resolution. We concluded that the better result of slice thickness versus NEX was related to the NEX increment and thin slice thickness.

• Journal of dental hygiene science
• /
• v.4 no.1
• /
• pp.21-25
• /
• 2004

In modern times, children's trauma is increasing every year because of car accidents and life environment changes. There is a limit to prevent traumatic damage for oral cavity organization. The fundamental data of trauma treatment and prevention will be presented through the survey and analysis of traumatic teeth damage. I examined 113 patients from Oct. 4th, 2000 to Feb. 27th, 2004 at Dept. of Children's Dental Clinic, Kangnung National University. The results are as follows. (1) The trauma frequency of male subjects is higher than that of female at a rate of 2.05:1. The average age is 5.27 for men and 5.27 for women. The highest percentage of trauma patients is among 2 year old children. It is 21.2%. (2) A patient survey was taken at a trauma treatment hospital. On the first day 34.4% of the patients had come to receive treatment of their first set of teeth. However, after a week, 38.8% of the patients had received treatment on their permanent teeth. (3) As a result of falling, 59% of patients needing treatment on their first set of teeth. 55.1% of patients is permanent teeth. As a result of bump against physical solid, 26.6% of patients is the first set of teeth and 26.5% of patients is permanent teeth. (4) Teeth damage happened at home. 42.1% were male. 35.1% were female. According to trauma, 59.4% of teeth damage happened at home. 28.6% of permanent teeth damage happened at school or kindergarten. (5) According to trauma, the number of teeth damaged was in the first set of teeth are as follows: 56.3%, one-31.3%, three or four-6.3% each. For permanent teeth: two-46.9%, one-28.6%, four over-16.3% and three-8.2%. Over four teeth is larger number for permanent teeth. (6) 56% of first set of teeth patients and 43.4% of permanent teeth patients were male. 56.8% of first set of teeth patients and 43.2% of permanent teeth were female. Trauma happened to both male and female frequently in the first set of teeth. (7) Most of the tooth damage which was in the first set of teeth and permanent teeth was done to the upper jaw. 75% of patients are the first set of teeth. 63.8% of patients are permanent teeth. Trauma is very high in the two mid teeth of the upper jaw. (8) According to trauma survey, 30.2% is from impulse. 28.0% is from crown fracture, 14.7% is from depression. 8.9% is from concussion. 7.1% is from full dislocation of a joint. 2.2% of patients are extrusion. 1.8% is from displacement. According to teeth damage trauma, 35.8% is pulse in the first set of teeth. The breaking of the crown of a tooth happened a lot in permanent teeth. (9) According to data, 43.2% of teeth damage in the first set of teeth goes without treatment. In permanent teeth, it is 38.9%. After treatment, 22.0% of first set of teeth treatment requires a dental pulp treatment. In permanent teeth, which is used for temporary acid etching resin restoration.