• Nuclear Engineering and Technology
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• v.56 no.3
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• pp.1066-1080
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• 2024

SMART100 has a containment pressure and radioactivity suppression system (CPRSS) for passive containment cooling system (PCCS). This prevents overheating and over-pressurization of a containment through direct contact condensation in an in-containment refueling water storage tank (IRWST) and wall condensation in a CPRSS heat exchanger (CHX) in an emergency cool-down tank (ECT). The Korea Atomic Energy Research Institute (KAERI) constructed scaled-down test facilities, SISTA1 and SISTA2, for the thermal-hydraulic validation of the SMART100 CPRSS. Three separate effect tests were performed using SISTA1 to confirm the heat removal characteristics of SMART100 CPRSS. When the low mass flux steam with or without non-condensable gas is released into an IRWST, the conditions for mitigation of the chugging phenomenon were identified, and the physical variables were quantified by the 3D reconstruction method. The local behavior of the non-condensable gas was measured after condensation inside heat exchanger using a traverse system. Stratification of non-condensable gas occurred in large tank of the natural circulation loop. SISTA2 was used to simulate a small break loss-of-coolant accident (SBLCOA) transient. Since the test apparatus was a metal tank, compensations of initial heat transfer to the material and effect of heat loss during long-term operation were important for simulating cooling performance of SMART100 CPRSS. The pressure of SMART100 CPRSS was maintained below the design limit for 3 days even under sufficiently conservative conditions of an SBLOCA transient.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.80-81
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• 2012

Recently, one of the critical issues in the etching processes of the nanoscale devices is to achieve ultra-high aspect ratio contact (UHARC) profile without anomalous behaviors such as sidewall bowing, and twisting profile. To achieve this goal, the fluorocarbon plasmas with major advantage of the sidewall passivation have been used commonly with numerous additives to obtain the ideal etch profiles. However, they still suffer from formidable challenges such as tight limits of sidewall bowing and controlling the randomly distorted features in nanoscale etching profile. Furthermore, the absence of the available plasma simulation tools has made it difficult to develop revolutionary technologies to overcome these process limitations, including novel plasma chemistries, and plasma sources. As an effort to address these issues, we performed a fluorocarbon surface kinetic modeling based on the experimental plasma diagnostic data for silicon dioxide etching process under inductively coupled C4F6/Ar/O2 plasmas. For this work, the SiO2 etch rates were investigated with bulk plasma diagnostics tools such as Langmuir probe, cutoff probe and Quadruple Mass Spectrometer (QMS). The surface chemistries of the etched samples were measured by X-ray Photoelectron Spectrometer. To measure plasma parameters, the self-cleaned RF Langmuir probe was used for polymer deposition environment on the probe tip and double-checked by the cutoff probe which was known to be a precise plasma diagnostic tool for the electron density measurement. In addition, neutral and ion fluxes from bulk plasma were monitored with appearance methods using QMS signal. Based on these experimental data, we proposed a phenomenological, and realistic two-layer surface reaction model of SiO2 etch process under the overlying polymer passivation layer, considering material balance of deposition and etching through steady-state fluorocarbon layer. The predicted surface reaction modeling results showed good agreement with the experimental data. With the above studies of plasma surface reaction, we have developed a 3D topography simulator using the multi-layer level set algorithm and new memory saving technique, which is suitable in 3D UHARC etch simulation. Ballistic transports of neutral and ion species inside feature profile was considered by deterministic and Monte Carlo methods, respectively. In case of ultra-high aspect ratio contact hole etching, it is already well-known that the huge computational burden is required for realistic consideration of these ballistic transports. To address this issue, the related computational codes were efficiently parallelized for GPU (Graphic Processing Unit) computing, so that the total computation time could be improved more than few hundred times compared to the serial version. Finally, the 3D topography simulator was integrated with ballistic transport module and etch reaction model. Realistic etch-profile simulations with consideration of the sidewall polymer passivation layer were demonstrated.

• Proceedings of the Membrane Society of Korea Conference
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• 1999.07a
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• pp.39-42
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• 1999

Perfluoropolymers represent the ultimate resistance to hostile chemical environments and high service temperature, attributed to the presence of fluorine in the polymer backbone, i.e. to the high bond energy of C-F and C-C bonds of fluorocarbons. Copolymers of Tetrafluoroethylene (TEE) and 2, 2, 4Trifluoro-5Trifluorometoxy- 1, 3Dioxole (TTD), commercially known as HYFLON AD, are amorphous perfluoropolymers with glass transition temperature (Tg)higher than room temperature, showing a thermal decomposition temperature exceeding 40$0^{\circ}C$. These polymer systems are highly soluble in fluorinated solvents, with low solution viscosities. This property allows the preparation of self-supported and composite membranes with desired membrane thickness. Symmetric and asymmetric perfluoropolymer membranes, made with HYFLON AD, have been prepared and evaluated. Porous and not porous symmetric membranes have been obtained by solvent evaporation with various processing conditions. Asymmetric membranes have been prepared by th wet phase inversion method. Measure of contact angle to distilled water have been carried out. Figure 1 compares experimental results with those of other commercial membranes. Contact angles of about 120$^{\circ}$for our amorphous perfluoropolymer membranes demonstrate that they posses a high hydrophobic character. Measure of contact angles to hexandecane have been also carried out to evaluate the organophobic character. Rsults are reported in Figure 2. The observed strong organophobicity leads to excellent fouling resistance and inertness. Porous membranes with pore size between 30 and 80 nanometers have shown no permeation to water at pressures as high as 10 bars. However high permeation to gases, such as O2, N2 and CO2, and no selectivities were observed. Considering the porous structure of the membrane, this behavior was expected. In consideration of the above properties, possible useful uses in th field of gas- liquid separations are envisaged for these membranes. A particularly promising application is in the field of membrane contactors, equipments in which membranes are used to improve mass transfer coefficients in respect to traditional extraction and absorption processes. Gas permeation properties have been evaluated for asymmetric membranes and composite symmetric ones. Experimental permselectivity values, obtained at different pressure differences, to various single gases are reported in Tab. 1, 2 and 3. Experimental data have been compared with literature data obtained with membranes made with different amorphous perfluoropolymer systems, such as copolymers of Perfluoro2, 2dimethyl dioxole (PDD) and Tetrafluorethylene, commercialized by the Du Pont Company with the trade name of Teflon AF. An interesting linear relationship between permeability and the glass transition temperature of the polymer constituting the membrane has been observed. Results are descussed in terms of polymer chain structure, which affects the presence of voids at molecular scale and their size distribution. Molecular Dyanmics studies are in progress in order to support the understanding of these results. A modified Theodoru- Suter method provided by the Amorphous Cell module of InsightII/Discover was used to determine the chain packing. A completely amorphous polymer box of about 3.5 nm was considered. Last but not least the use of amorphous perfluoropolymer membranes appears to be ideal when separation processes have to be performed in hostile environments, i.e. high temperatures and aggressive non-aqueous media, such as chemicals and solvents. In these cases Hyflon AD membranes can exploit the outstanding resistance of perfluoropolymers.

• The Korean Journal of Nuclear Medicine Technology
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• v.22 no.1
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• pp.67-75
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• 2018

Purpose The purpose of this study is to investigate and analyze the external dose rates of $^{18}F-FDG$ Whole Body PET/CT patients by distance, and to identify the main factors that contribute to the reduction of radiation dose by checking the cumulative doses of nuclear medicine technologist(NMT). Materials and Methods After completion of the $^{18}F-FDG$ Whole Body PET/CT scan($75.4{\pm}3.3min$), the external dose rates of 106 patients were measured at a distance of 0, 10, 30, 50, and 100 cm from the chest. Gender, age, BMI(Body Mass Index), fasting time, diabetes mellitus, radiopharmaceutical injection information, creatine value were collected to analyze individual factors that could affect external dose rates from a patient's perspective. From the perspective of NMT, personal pocket dosimeters were worn on the chest to record accumulated dose of NMT who performed the injection task($T_1$, $T_2$ and $T_3$) and scan task($T_4$, $T_5$ and $T_6$). In addition, patient contact time with NMT was measured and analyzed. Results External dose rates from the patient for each distance were calculated as $246.9{\pm}37.6$, $129.9{\pm}16.7$, $61.2{\pm}9.1$, $34.4{\pm}5.9$, and $13.1{\pm}2.4{\mu}Sv/hr$ respectively. On the patient's aspect, there was a significant difference in the proximity of gender, BMI, Injection dose and creatine value, but the difference decreased as the distance increased. In case of dialysis patient, external dose rates for each distance were exceptionally higher than other patients. On the NMT aspect, the doses received from patients were 0.70, 1.09, $0.55{\mu}Sv/person$ for performing the injection task($T_1$, $T_2$, and $T_3$), and were 1.25, 0.82, $1.23{\mu}Sv/person$ for performing the scan task($T_4$, $T_5$, $T_6$). Conclusion we found that maintaining proper distance with patient and reducing contact time with patient had a significant effect on accumulated doses. Considering those points, efforts such as sufficient water intake and encourage of urination, maintaining the proper distance between the NMT and the patient(at least 100 cm), and reducing the contact time should be done for reducing dose rates not only patient but also NMT.

• Journal of Korean Academy of Nursing
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• v.8 no.2
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• pp.89-102
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• 1978

Owing to the development of modern science, prolonging man's life, the sudden increase of population and betterment of the standard of living has increased health needs. In order to fulfill these health needs, more active plans for developing health should be made. Health education is one of the methods at hand that can improve the health behavior of the community and the individual through the contact of individuals with their groups. Proper understanding of the characteristics of the sampled group and participation of individuals within the community for the development of their health plan are needed for efficient health education. This study was attempted for the purpose of presenting some data helpful for pre-paring the fundamentals of a health education plan that can improve personal health maintenance practice of a community through efficient health education by investigating the relationship between the response of subjects to personal health maintenance practice and selected decisive factors in personal health maintenance practice. The subjects for this study were a systematic sample of 120 housewives selected from 600 housewives from B Zone Apt. Younhi-3-Dong in Seoul. Data was collected for 4 days from May 16th to May 19th, 1578 through personal interviews with questionnaires by well trained interviewers. Percentage, t-test and stepwise multiple regression analysis by use of EDPS were employed for statistical analysis. Results of this study can be summarized : 1. General characteristics of subjects Subjects over 20 and below 40 years of age formed 62.5% of the toed and the rest were subjects of 40 years and upward. 76.7% of the subjects have less than 4 children. 51.3% of the subjects had completed at least the senior high school course. 2. The response of subjects to personal health maintenance practice. Ratios of personal health maintenance practice to the maximum score for each category are as follows; 84.1% in the category of population and family planning, which was the highest ratio; 82.4% in the prevention of accidents; 68.0% in control of communicable disease; 67.8% in personal health care and habits of daily life, 64.3% in mental health and 52.5% in control of parasites, which was the lowest. 3. The response of subjects to selected decisive factors. in personal health maintenance practice. The arithmetic mean of the score for each decisive factor was as follows: the mutual relation between family members marked 18.33, which is under 73,3% of the maximum score; the degree of interest in health marked 34.48, 70.0% of the maximum score: the degree of utilization and demand for health care facilities marked 25.79 or 64.5% of the maximum score and health maintenance of the family marked 11.58, 43.6% of the maximum score. 4. The relationship between personal health maintenance practice and general characteristics of subjects. 1) There was a significant difference in the numbers of children. (t = 1.83, d.f. =117, p< 0.1) 2) There was a significant difference in the contact rates with mass-media, (t = 5.02, d.f. = 118, p< 0,05) 5. The multiple correlation between personal health maintenance practice and their selected decisive factors. 1) The factor“the degree of interest in health”could account for personal health maintenance practice in 43.6% of the sample. (R = 0.6602, R²= 0,4359, F = 91.1678, p< 0.001) 2) When the factor,“health maintenance of family”is added to this, it accounts for 51.2% of personal health maintenance practice. (R = 0.7158, R²= 0.5124, F = 61.4653, p< 0.001) 3) When the factor,“mutual relations between family members”is also included, it accounts for 53.7% of personal health maintenance practice. (R = 0.7324, R²= 0.5365, F = 44.7509, p< 0.001) 4) When the factor, “the degree of utilization and demand for health care facilities”is included, it accounts for 55.1% of personal health maintenance practice. (R = 0.7421, R²= 0.5507, F = 35.2430, p< 0.001).

• Journal of Food Hygiene and Safety
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• v.33 no.2
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• pp.102-109
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• 2018

In the present study, a variety of polylactide (PLA) articles (n = 211) were tested for migration of lead (Pb), cadmium (Cd) and arsenic (As) into the food simulant (4% v/v acetic acid). Pb, Cd, and As were analyzed by inductively coupled plasma mass spectrometry (ICP-MS). Migration tests were performed at $70^{\circ}C$ and $100^{\circ}C$ for 30 min. The amounts of Pb, Cd, and As increased at $100^{\circ}C$ for 30 min compared with levels at $70^{\circ}C$. However, the migration at both conditions was very low. The maximum level of Pb at $100^{\circ}C$ for 30 min corresponded to 1% of the migration limit. The estimated daily intakes (EDI) based on safety evaluation ranged from $2.5{\times}10^{-5}$ to $2.0{\times}10^{-3}{\mu}g/kg\;bw/day$ for Pb, Cd, and As. The EDI calculated from migration of Pb at $100^{\circ}C$ for 30 min in PLA was the maximum value, $2.0{\times}10^{-3}{\mu}g/kg\;bw/day$, which corresponded to 0.055% of provisional tolerable weekly intake (PTWI, $25{\mu}g/kg\;bw/week$). The data from this study represent a valuable source for science-based safety control and management of hazardous heavy metals migrating from polylactide food contact materials.

• Applied Chemistry for Engineering
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• v.26 no.3
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• pp.311-318
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• 2015

This work investigated the plasma treatment of aqueous bisphenol A (BPA) solution and mineralization pathways. For the effective contact between plasmatic gas and aqueous BPA solution, the plasma was created inside a porous ceramic tube, which was uniformly dispersed into the aqueous solution through micro-pores of the ceramic tube. Effects of the gas flow rate, applied voltage and treatment time on the decomposition of BPA were examined, and analyses using ultraviolet (UV) spectroscopy, ion chromatography and gas chromatography-mass spectrometry were also performed to elucidate mineralization mechanisms. The appropriate gas flow rate was around $1.0L\;min^{-1}$; when the gas flow rate was too high or too low, the BPA decomposition performance at a given electric power decreased. The increase in the voltage improves the BPA decomposition due to the increased electric power, but the energy required to remove BPA was similar, regardless of the voltage. Under the condition of $1.0L\;min^{-1}$ and 20.8 kV, BPA at an initial concentration of $10L\;min^{-1}$ (volume : 1 L) was successfully treated within 30 min. The intermediates produced by the attack of ozone and hydroxyl radicals on BPA were further oxidized to stable compounds such as acetate, formate and oxalate.

• Archives of design research
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• v.13 no.3
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• pp.211-220
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• 2000

Cultural contact, which means a current that an influential culture diffuses to another, represents the penetration of the one to the other in a negative respect and'mixture'or 'fusion'of them in an affirmative respect. Fusion of cultures was not easy to take place in the past when nationalism and ultranationalism suppressed it ideologically, inconvenient transportation and communications were obstacles to it, and most of countries were under the influences of folk religions. Today, however, mutually heterogeneous cultures can be shared by a lot of things such as collapse of a view of nation resulted from globalization, breakdown of regional characteristics, abolition of trade barriers, freedom of communications and realtime information network. Those have rendered fusion possible. Fusion in this modern consuming society is extending much faster and more extensively than at any time in the past. In addition, more and more cultural elements seem to collide and compromise with one another in the name of fusion, not relaxing the bridle of fusion, from the present situations that preference in consumption becomes subdivided and a variety of individuality is strongly attempted to seek for, This study is on the subject of the properties of'Fusion', one of new styles in a mass culture, especially focused on sociologic cultural phenomena. Furthermore, it is expected to look for a fusion in interior design which expresses sociologic cultural phenomena most in a field of design, to examine it theoretically, and to prospect a future trend of fusion design based on investigation of the latest prevailing trend.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.35 no.4
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• pp.227-235
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• 2013

Purpose: High risk human papillomavirus (HPV) is the main source of cervical cancer, nearly up to 100%. Because there are no affordable data regarding the incidence of HPV in different sites of oral cavity, the purpose of this study is to review the previous article and to find out about the incidence and types of HPV in specific areas of oral cavity. Methods: We examined a total of 106 patients with oral cavity cancer for HPV detection. Available DNA chip (MY-HPV chip kit$^{(R)}$, Mygene Co., Korea) was used for the detection of low risk HPV types (6, 11, 34, 40, 42, 43, 44) and high risk HPV types (16, 18, 31, 33, 35, 39, 45, 51, 52, 54, 56, 58). Patients were previously diagnosed as invasive cancer of oral cavity. Specimen used for HPV detection was extracted from the main mass during resection and were tested for HPV type, performed by a DNA chip method. Results: Histologic results showed that there were squamous cell carcinomas, mucoepidermoid carcinomas, cystadenocarcinomas, leiomyosarcoma and etc. Among HPV positive cancer, 2 patients showed positive for high risk HPV type 16, 3 patients showed positive for low risk HPV type 6 and the other 2 patients were positive for other types of HPV. Of the 7 patients with HPV positive, 4 patients were on the tongue, 3 on the lower gingiva. Conclusion: Most of the HPV positive cancers were on the tongue in our study. Cervical cancer of HPV infection is reported to be increasing in our society and because HPV infection largely spreads by sexual contact, the incidence of oral cancer with HPV infection is greatly assumed to be on the increase, simultaneously. Because the incidence of HPV on specific areas of oral cavity among oral cancer patients is not identified, more studies are ongoing.

• Korean Journal of Materials Research
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• v.20 no.4
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• pp.175-180
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• 2010

Transparent conducting oxide (TCO) films are widely used for optoelectronic applications. Among TCO materials, zinc oxide (ZnO) has been studied extensively for its high optical transmission and electrical conduction. In this study, the effects of $O_2$ plasma pretreatment on the properties of Ga-doped ZnO films (GZO) on polyethylene naphthalate (PEN) substrate were studied. The $O_2$ plasma pretreatment process was used instead of conventional oxide buffer layers. The $O_2$ plasma treatment process has several merits compared with the oxide buffer layer treatment, especially on a mass production scale. In this process, an additional sputtering system for oxide composition is not needed and the plasma treatment process is easily adopted as an in-line process. GZO films were fabricated by RF magnetron sputtering process. To improve surface energy and adhesion between the PEN substrate and the GZO film, the $O_2$ plasma pre-treatment process was used prior to GZO sputtering. As the RF power and the treatment time increased, the contact angle decreased and the RMS surface roughness increased significantly. It is believed that the surface energy and adhesive force of the polymer surfaces increased with the $O_2$ plasma treatment and that the crystallinity and grain size of the GZO films increased. When the RF power was 100W and the treatment time was 120 sec in the $O_2$ plasma pretreatment process, the resistivity of the GZO films on the PEN substrate was $1.05\;{\times}\;10^{-3}{\Omega}-cm$, which is an appropriate range for most optoelectronic applications.