• Journal of Radiation Protection and Research
• /
• v.40 no.2
• /
• pp.79-86
• /
• 2015

$^3He$ gas has been used for neutron monitors as the neutron converter owing to its advantages such as high sensitivity, good ${\gamma}$-discrimination capability, and long-term stability. However, $^3He$ is becoming more difficult to obtain in last few years due to a global shortage of $^3He$ gas. Accordingly, the cost of a neutron monitor using $^3He$ gas as a neutron converter is becoming more expensive. Demand on a neutron monitor using an alternative neutron conversion material is widely increased. $^{10}B$ has many advantages among various $^3He$ alternative materials, as a neutron converter. In order to develop a neutron converter using $^{10}B$ (actually $B_4C$), we calculated the optimal thickness of a neutron converter with a Monte Carlo simulation using MCNP6. In addition, a neutron converter was fabricated by the Ar sputtering method and the neutron signal detection efficiencies were measured with respect to various thicknesses of fabricated a neutron converter. Also, we developed a 2-dimensional multi-wire proportional chamber (MWPC) for neutron beam profile monitoring using the fabricated a neutron converter, and performed experiments for neutron response of the neutron monitor at the 30 MW research reactor HANARO at the Korea Atomic Energy Research Institute. The 2-dimensional MWPC with boron ($B_4C$) neutron converter was proved to be useful for neutron beam monitoring, and can be applied to other types of neutron imaging.

• Progress in Medical Physics
• /
• v.17 no.1
• /
• pp.47-53
• /
• 2006

The accuracy of the dosimetry in the Cyberknife system is accomplishing important role from all processes of the stereotactic radiosurgery. In this study, we estimated relative output factors for Cyberknife. All measurements were peformed by six different detectors: diode detector, X-Omat V film, Gafchromic EBT film, 0.015 cc, 0.125 cc and 0.6 cc ionization chamber The diode detector and three ionization chambers peformed using water phantom at 80 cm SSD and 1.5 cm depth. When the film measurements were peformed, the water phantom was replaced with a solidwater phantom. Each collimator normalized with respect to the output factor of the largest collimator (60 mm). For the collimators over than 30 mm, the output factors from the different detectors showed a good agreement within 0.5% except 0.6 cc ion chamber For the collimators less than 15 mm, there were substantial differences In the output factors among different detectors. That is, the value of output factor for the 5 mm collimator of a diode and Gafchromic film was each $0.656{\pm}0.009$ and $0.777{\pm}0.013$. In the ion chamber and diode detector, those difference were due to the presence of large dose gradients and lack of electronic equilibrium in narrow megavoltage x-ray beams Therefore, the Gafchromic EBT film were considered more accurate than the others detectors.

• Progress in Medical Physics
• /
• v.17 no.1
• /
• pp.1-5
• /
• 2006

A parallel plate detector containing PTFE films in FEP film for relative dosimetry was designed to measure the response of detectors to S and 10 MV X-rays from a medical linear accelerator through different thicknesses of lead. The dielectric materials were 100 m thick. The set-up conditions for measurements with this detector were as follows: SSD=100 cm the test detector was at a depth of 5 cm and the reference chamber was at a depth of 10 cm from the phantom surface for 6 and 10 MV X-rays. Lead blocks were designed to cover the irradiated field. They were added to the tray to increase thickness sequentially. We found that the detector response decreased exponentially with the thickness of lead added. The linear attenuation coefficients of the test detector and reference chamber were 0.1414 and 0.541, respectively, for 6 MV X-rays and 0.1358 and 0.5279 for 10 MV X-rays. The test detector response was greater than that of the reference chamber. The response function was calculated from the measured values of the test detector and reference chamber using optimization. These optimized constants for the detector response function were independent of theenergy. As a result of optimizing the response function between detectors, the use of a relative dosimeter was validated, because the response of the test detector was 1% for 6 MV X-rays and 4% for 10 MV X-rays.

• Tuberculosis and Respiratory Diseases
• /
• v.42 no.4
• /
• pp.474-480
• /
• 1995

Background: In spite of initial intensive and long-term chemotherapy for pulmonary tuberculosis, many problems remain in the treatment of the residual lesion. The role of surgical intervention for pulmonary tuberculosis is getting rid of such residual lesion of pulmonary tuberculosis to support the healing process and to induce bacteriologically negative conversion in the end. Method: We experienced 30 cases of pulmonary resection for pulmonary tuberculosis from Aug. 1994 through Apr. 1995 in National Masan Tuberculosis Hospital. We conducted retrospective study to analyze several variables for the cases. Results: 1) The ratio between male and female was 4:1(male 24, female 6) and the age of peak incidence was in 3rd and 4th decades. 2) Indications for pulmonary resection in the radiographic findings were cavitary lesions of 19 cases(63.3%), destroyed one side of 8 cases(26.7%) and destroyed one lobe of 3 cases(10%). 3) 16 of 20 cases with unilateral lesions and all of 10 cases with bilateral lesions on chest X-ray films showed AFB positive on preoperative sputum smears. 14 cases(87.5%) of unilateral lesions and 9 cases(90%) of bilateral ones were converted into AFB negative postoperatively. Negative conversion rates of pneumonectomy and lobectomy cases were 100% and 85.7%, respectively. 4) Preoperative combined disease was 3 cases(10%) of DM and postoperative complications were 2 cases(6.7%) of dead space and no death. Conclusion: Chemotherapy only has some limitation in treatment of all tuberculosis. So, surgical intervention for pulmonary tuberculosis is an effective method as partner of chemotherapy.

• Tuberculosis and Respiratory Diseases
• /
• v.61 no.5
• /
• pp.463-472
• /
• 2006

Background: Since video-assisted thoracoscopic surgery (VATS) was introduced as a new treatment modality for empyema thoracis, numerous reports have suggested that VATS is a more effective treatment method than the traditional methods that mainly use antibiotics and drainage apparatus. However, no confirmative evidence of the superiority of VATS over the traditional method has been provided yet. Methods: We attempted to evaluate the efficacy of VATS for the treatment of empyema thoracis by reviewing past medical records and simple chest films. First, we divided the patients into two groups based on the treatment method: group A of 15 patients who were treated with the traditional method between January 2001 and December 2003, and group B of 9 patients who were treated with VATS between December 2003 and August 2006. The final outcomes used in this study were the number of days of hospital stay, chest tube duration, leukocytosis duration, febrile duration, and intravenous antibiotics usage duration. In addition, radiological improvements were compared. Results: The mean age(${\pm}$standard deviation) of 11 men and 4 women in group A was $58.2{\pm}15.7$ years, and of 9 men and 2 women in group B was $51.6{\pm}9.5$ years. Group B had a significantly shorter hospital stay ($16.6{\pm}7.4$ vs. $33.7{\pm}22.6$ days; p=0.014), shorter chest tube duration ($10.5{\pm}5.7$ vs. $19.5{\pm}14.4$ days; p=0.039), shorter leukocytosis duration ($6.7{\pm}6.5$ vs. $18.8{\pm}13.2$ days; p=0.008), shorter febrile duration ($0.8{\pm}1.8$ vs. $9.4{\pm}9.2$ days; p=0.004), and shorter duration of intravenous antibiotics usage ($14.9{\pm}6.4$ vs. $25.4{\pm}13.9$ days; p=0.018). However, radiological improvements did not show any statistical differences. Conclusion: Early application of VATS for empyema thoracis treatment reduced hospital stay, thoracostomy tube duration, leukocytosis duration, febrile duration, and antibiotics usage duration in comparison with the traditional methods. The early performing of VATS might be an effective treatment modality for empyema thoracis.

• Proceedings of the KOR-BRONCHOESO Conference
• /
• 1981.05a
• /
• pp.41.2-41
• /
• 1981

Tonsillectomy and adenoidectomy are the most common operations in the ENT field. Recent emphasis on careful selection of patients for these procedures derives from concern for complications of surgery, as well as the immunologic and anatomic functions of tonsils and adenoids. Adenoidectomy can relieve nasopharyngeal airway obstruction caused by enlarge adenoids, and can prevent complications such as heart failure and recurrent or chronic otitis media. We researched 117 cases of tonsilloadenoidectomy patients and 266 patients having routine examination from March, 1979 to February, 1981, and described the A/N ratio derived from linear measurements of lateral radiographs of the nasopharynx. The results of Impedance Audiometry and X-ray films from 117 cases of T&A patients were compared: 1) The average A/N ratio by age groups for 266 cases of normal children showed: 0.508 for age group, 0 to 3 years old, 0.533 for age group, 4 to 6 years old, 0.524 for age group, 7 to 9 years old, 0.519 for age group, 10 to 12 years old, 0.507 for age group, 13 to 15 years old, 0.481 for age group over 15 years old. The peak value lies in the age group of 4 to 6 years old. The sex difference of A/N ratio was not significant. 2) The average A/N ratio by age groups from 117 cases of T&A patients showed: 0.709 for age group, 0 to 3 years old, 0.733 for age group, 4 to 6 years old, 0.693 for age group, 7 to 9 years old, 0.707 for age group, 10 to 12 years old, 0.620 for age group, 13 to 15 years old, 0.756 for age group over 15 years old. 3) Among the 117 cases of T&A patients, the average A/N ratio for 57 cases in normal tympanogram was 0.688 and the average A/N ratio for 60 cases in abnormal tympanogram was 0.705. 4) Among 57 cases in abnormal tympanogram: 6 cases (10.5%) showed 0.40-0.59 of A/N ratio, 44 cases (77.2%) showed 0.60-0.79 of A/N ratio, and 7 cases (12.3%) showed 0.80-0.99 of A/N ratio. 5) Among 117 cases of T&A patients, 3 of 15 cases showing A/N ratio under 0.6, and 67 of 102 cases showing A/N ratio over 0.6, had paranasal sinusitis.

• Korean Journal of Materials Research
• /
• v.10 no.11
• /
• pp.778-783
• /
• 2000

Effects of the $Al_2$O$_3$surface protective layer, deposited on the SnO$_2$sensing layer by aerosol flame deposition (AFD) method, on the sensing properties of SnO$_2$thin film ags sensors were investigated.Effects of Pt doping to the $Al_2$O$_3$surface protective layer on the selectivity of CH$_4$ gas were also investigated. 0.3$\mu\textrm{m}$ thick SnO$_2$thin sensing layers on Pt electrodes were prepared by R.F. magnetron sputtering with R.F. power of 50 W, at working pressure of 4mTorr, and at 20$0^{\circ}C$ for 30 min. $Al_2$O$_3$surface protective layers on SnO$_2$layers were prepared by AFD using a diluted aluminum nitrade (Al(NO$_3$).9$H_2O$) solution. The sensitivity of CO gas in the SnO$_2$gas sensor with an $Al_2$O$_3$surface protective layer was significantly decreased. But that of CH$_4$gas remained almost same with pure SnO$_2$gas sensor. This result shows that the selectivity of CH$_4$gas is increased because of the $Al_2$O$_3$surface protective layer. In the case of SnO$_2$gas sensors with Pt-doped $Al_2$O$_3$surface protective layers, low sensing property to CO gas and high sensing property to CH$_4$were observed. This results in the increasing of selectivity of CH$_4$gas selectivity are discussed.

• Korean Journal of Materials Research
• /
• v.4 no.7
• /
• pp.759-766
• /
• 1994

Our investigation aimed to reduce the leakage current of $Ta_2O_5$ thin film capacitor by layering SnOz thin film layer under Ta thin film, thereby supplying extra oxygen ions from the $SnO_{2}$ underlayer to enhance the stoichiometry of $Ta_2O_5$ during the oxidation of Ta thin film. Tantalum was evaporated by e-beam or sputtered on p-Si wafers with various deposition temperatures and was oxidized by dry--oxygen at the temperatures between $500^{\circ}C$ and $900^{\circ}C$. Aluminum top and bottom electrodes were formed to make Al/$Ta_2O_5$/p-Si/Al or $Al/Ta_2O_5/SnO_2$p-Si/AI MIS type capacitors. LCR meter and pico-ammeter were used to measure the dielectric constants and leakage currents of the prepared thm film capacitors. XRD, AES and ESCA were employed to confirm the crystallization of the thin f~lm and the compositions of the films. Dielectric constant of $Ta_2O_5$ thin film capacitor with $SnO_{2}$ underlayer was found to be about 200, which is about 10 times higher than that of $Ta_2O_5$ thin film capacitor without $SnO_{2}$ underlayer. In addition, higher oxidation temperatures increased the dielectric constants and reduced the leakage current. Higher deposition temperature generally gave lower leakage current. $Ta_2O_5/SnO_2$ capacitor deposited at $200^{\circ}C$ and oxidized at $800^{\circ}C$ showed significantly lower leakage current, $10^{-7}A/\textrm{cm}^2$ at $4 \times 10^{5}$V/cm, compared to the one without $SnO_{2}$ underlayer. XRD showed that $Ta_2O_5$ thin film was crystallized above $700^{\circ}C$. AES and ESCA showed that initially the $SnO_{2}$, underlayer supplied oxygen ions to oxidize the Ta layer, however, Sn also diffused into the Ta thin film layer to form a new $Ta_xSn_YO_Z$ , ternary oxide layer after all.

• Journal of Bio-Environment Control
• /
• v.28 no.3
• /
• pp.197-203
• /
• 2019

This study was carried out to investigate the effect of chlorine water and plasma gas treatment on the quality and microbial control of Latuca indica L. baby Leaf during storage. Latuca indica L. baby leaves were harvested from a plant height of 10cm. They were sterilized with $100{\mu}L{\cdot}L^{-1}$ chlorine water and plasma-gas (1, 3, and 6hours), and packaged with $1,300cc{\cdot}m^{-2}{\cdot}day^{-1}{\cdot}atm^{-1}$ films and then stored at $8{\pm}1^{\circ}C$ and RH $85{\pm}5%$ for 25days. During storage, the fresh weight loss of all treatments were less than 1.0%, and the carbon dioxide and oxygen concentrations in packages were 6-8% and 16-17%, respectively for all treatments in the final storage day. The concentration of ethylene in the packages fluctuated between $1-3{\mu}L{\cdot}L^{-1}$ during the storage and the highest concentration of ethylene was observed at 6 hours plasma treatment in the final storage day. The off-odor of all treatments were almost odorless, the treatments of chlorine water and 1 hour plasma maintained the marketable visual quality until the end of storage. Chlorophyll content and Hue angle value measured at the final storage day were similar to those measured before storage in chlorine water and 1 hour of plasma treatments. E. coli was not detected immediately after sterilization in all sterilization treatments. After 6 hours of plasma treatment, the total bacteria fungus counts were lower than the domestic microbial standard for agricultural product in all sterilization treatments. The total aerobic counts in the end storage day increased compared to before storage, whereas E. coli was not detected in all sterilization treatments. The sterilization effect against bacteria and fungi was the best in chlorine water treatment. Plasma treatment showed sterilization effects, but within a prolonged period of time. In addition, the sterilization effect decreased gradually. These results suggest that chlorine water and plasma treatment were effective in maintaining Latuca indica L. baby Leaf commerciality and controlling microorganisms during postharvest storage.

• Journal of the Microelectronics and Packaging Society
• /
• v.27 no.4
• /
• pp.83-89
• /
• 2020

For the past few decades, as part of efforts to protect the environment where fossil fuels, which have been a key energy resource for mankind, are becoming increasingly depleted and pollution due to industrial development, ecofriendly secondary batteries, hydrogen generating energy devices, energy storage systems, and many other new energy technologies are being developed. Among them, the lithium-ion battery (LIB) is considered to be a next-generation energy device suitable for application as a large-capacity battery and capable of industrial application due to its high energy density and long lifespan. However, considering the growing battery market such as eco-friendly electric vehicles and drones, it is expected that a large amount of battery waste will spill out from some point due to the end of life. In order to prepare for this situation, development of a process for recovering lithium and various valuable metals from waste batteries is required, and at the same time, a plan to recycle them is socially required. In this study, we introduce a nanoscale pattern transfer printing (NTP) process of Li2CO3, a representative anode material for lithium ion batteries, one of the strategic materials for recycling waste batteries. First, Li2CO3 powder was formed by pressing in a vacuum, and a 3-inch sputter target for very pure Li2CO3 thin film deposition was successfully produced through high-temperature sintering. The target was mounted on a sputtering device, and a well-ordered Li2CO3 line pattern with a width of 250 nm was successfully obtained on the Si substrate using the NTP process. In addition, based on the nTP method, the periodic Li2CO3 line patterns were formed on the surfaces of metal, glass, flexible polymer substrates, and even curved goggles. These results are expected to be applied to the thin films of various functional materials used in battery devices in the future, and is also expected to be particularly helpful in improving the performance of lithium-ion battery devices on various substrates.