• Analytical Science and Technology
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• v.29 no.2
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• pp.65-72
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• 2016

This study presented an analytical method for detecting radium in soils using a liquid scintillation counter (LSC). The isotope ²²⁶Ra was extracted from soil using the fusion method and then separated from interfering radionuclides using the precipitation method. Radium was coprecipitated as sulfate salts with barium (Ba) and then converted into Ba(Ra)CO₃, which is soluble in an acidic solution. The isotope ²²²Rn, the decay progeny of ²²⁶Ra, was trapped in a water immiscible cocktail and analyzed by LSC. The pulse shape analysis (PSA) level was estimated using ⁹⁰Sr and ²²⁶Ra standard solutions. The figure of merit was the highest at PSA 80, while the alpha spillover was the lowest at PSA 80. The counting efficiency was 243 ± 2% in a glass vial. This analytical method was verified with International Atomic Energy Agency (IAEA) reference materials, including IAEA-312, IAEA-314, and IAEA-315. The recovery ranged from 60–82%, while the relative bias between the measured value and the recommended value was less than 10%. The minimum detectable activity was 2.1 Bq kg⁻¹ with dry mass 1 g, the background count rate of 0.02 cpm, the recovery rate of 70% and counting time of 30 min.

• Journal of the Korean Society of Safety
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• v.26 no.4
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• pp.7-13
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• 2011

A study on reliability estimation of sequential-ordered multiple failure modes, which are sequentially ordered between failure modes in a considering system, was performed. Especially, an approach to estimate the probabilities of failure modes has been proposed under an assumption that failure modes are mutually exclusive and sequentially ordered by only a critical variable. A feasibility of the proposed approach were studied by a practical example, which is a reliability estimation of passive safety systems for a probabilistic safety assessment(PSA) of a very high temperature reactor(VHTR) that is under development as a future nuclear system with enhanced safety features. It is difficult to define a robust failure state of this nuclear system because of its enhanced radiation release characteristics, so the new approach is a useful concept to estimate not only its safety but also a PSA. A feasibility study applied two failure modes(e.g., small and large release of radioactive materials) with considering the integrated behavior of this nuclear system. It is expected that the multiple release states for a practical estimation can be easily extended to the aforementioned example. It was found out that the proposed approach was a useful technique to cover the unfavorable features of this nuclear system as to performing a VHTR PSA.

• Earthquakes and Structures
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• v.11 no.2
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• pp.327-346
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• 2016

The 2012 Emilia (Italy) earthquakes struck a highly industrialized area including several thousands of industrial prefabricated buildings. Due to the lack of specific design and detailing for earthquake resistance, precast reinforced concrete (RC) buildings suffered from severe damages and even partial or total collapses in many cases. The present study reports a data inventory of damages from field survey on prefabricated buildings. The damage database concerns more than 1400 buildings (about 30% of the total precast building stock in the struck region). Making use of the available shakemaps of the two mainshocks, damage distributions were related with distance from the nearest epicentre and corresponding Pseudo-Spectral Acceleration for a period of 1 second (PSA at 1 s) or Peak Ground Acceleration (PGA). It was found that about 90% of the severely damaged to collapsed buildings included into the database stay within 16 km from the epicentre and experienced a PSA larger than 0.12 g. Moreover, 90% of slightly to moderately damaged buildings are located at less than 25 km from the epicentre and were affected by a PSA larger than 0.06 g. Nevertheless, the undamaged buildings examined are almost uniformly distributed over the struck region and 10% of them suffered a PSA not lower than 0.19g. The damage distributions in terms of the maximum experienced PGA show a sudden increase for $PGA{\geq}0.28g$. In this PGA interval, 442 buildings were collected in the database; 55% of them suffered severe damages up to collapse, 32% reported slight to moderate damages, whereas the remaining 13% resulted undamaged.

• Journal of Environmental Science International
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• v.23 no.5
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• pp.943-962
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• 2014

Industrial gas drying, dilute gas mixtures purification, air fractionation, hydrogen production from steam reformers and petroleum refinery off-gases, etc are conducted by using adsorptive separation technology. The pressure swing adsorption (PSA) has certain advantages over the other methods, such as absorption and membrane, that are a low energy requirement and cost-effectiveness. A key component of PSA systems is adsorbents that should be highly selective to a gas being separated from its mixture streams and have isotherms suitable for the operation principle. The six standard types of isotherms have been examined in this review, and among them the best behavior in the adsorption of $CO_2$ as a function of pressure was proposed in aspects of maximizing a working capacity upon excursion between adsorption and desorption cycles. Zeolites and molecular sieves are historically typical adsorbents for such PSA applications in gas and related industries, and their physicochemical features, e.g., framework, channel structure, pore size, Si-to-Al ratio (SAR), and specific surface area, are strongly associated with the extent of $CO_2$ adsorption at given conditions and those points have been extensively described with literature data. A great body of data of $CO_2$ adsorption on the nanoporous zeolitic materials have been collected according to pressure ranges adsorbed, and these isotherms have been discussed to get an insight into a better $CO_2$ adsorbent for PSA processes.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.8
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• pp.3383-3389
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• 2014

Background: Prostate cancer is rapidly increasing in Korea and professional societies have requested adding prostate specific antigen (PSA) testing to the National Cancer Screening Program (NCSP), but this started a controversy in Korea and neutral evidence on this issue is required more than ever. The purpose of this study was to provide economic evidence to the decision makers of the NCSP. Materials and Methods: A cost-utility analysis was performed on the adoption of PSA screening program among men aged 50-74-years in Korea from the healthcare system perspective. Several data sources were used for the cost-utility analysis, including general health screening data, the Korea Central Cancer Registry, national insurance claims data, and cause of mortality from the National Statistical Office. To solicit the utility index of prostate cancer, a face-to-face interview for typical men aged 40 to 69 was conducted using a Time-Trade Off method. Results: As a result, the increase of effectiveness was estimated to be very low, when adopting PSA screening, and the incremental cost effectiveness ratio (ICER) was analyzed as about 94 million KRW. Sensitivity analyses were performed on the incidence rate, screening rate, cancer stage distribution, utility index, and treatment costs but the results were consistent with the base analysis. Conclusions: Under Korean circumstances with a relatively low incidence rate of prostate cancer, PSA screening is not cost-effective. Therefore, we conclude that adopting national prostate cancer screening would not be beneficial until further evidence is provided in the future.

• Nuclear Engineering and Technology
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• v.52 no.10
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• pp.2221-2229
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• 2020

After the Fukushima Daiichi nuclear power plant (NPP) accident, level 3 probabilistic safety assessment (PSA) has emerged as an important task in order to assess the risk level of the multi-unit NPPs in a single nuclear site. Accurate calculation of the radionuclide concentrations and exposure doses to the public is required if a nuclear site has multi-unit NPPs and large number of people live near NPPs. So, there has been a great need to develop a new method or procedure for the fast and accurate offsite consequence calculation for the multi-unit NPP accident analysis. Since the multi-unit level 3 PSA is being currently performed assuming that all the NPPs are located at the same position such as a center of mass (COM) or base NPP position, radionuclide concentrations or exposure doses near NPPs can be drastically distorted depending on the locations, multi-unit NPP alignment, and the wind direction. In order to overcome this disadvantage of the COM method, the idea of a new multiple location (ML) method was proposed and implemented into a new tool MURCC (multi-unit radiological consequence calculator). Furthermore, the MURCC code was further improved for the multi-unit level 3 PSA that has the arbitrary number of multi-unit NPPs. The objectives of this study are to (1) qualitatively and quantitatively compare COM and ML methods, and (2) demonstrate the strength and efficiency of the ML method. The strength of the ML method was demonstrated by the applications to the multi-unit long-term station blackout (LTSBO) accidents at the four-unit Vogtle NPPs. Thus, it is strongly recommended that this ML method be employed for the offsite consequence analysis of the multi-unit NPP accidents.

• Nuclear Engineering and Technology
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• v.47 no.2
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• pp.204-211
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• 2015

Probabilistic safety assessment (PSA) has had a significant role in quantitative decision-making by finding design and operational vulnerabilities and evaluating cost-benefit in improving such weak points. In particular, it has been widely used as the core methodology for risk-informed applications (RIAs). Even though the nature of PSA seeks realistic results, there are still "conservative" aspects. One of the sources for the conservatism is the assumptions of safety analysis and the estimation of failure frequency. Surveillance, diagnosis, and prognosis (SDP), utilizing massive databases and information technology, is worth highlighting in terms of its capability for alleviating the conservatism in conventional PSA. This article provides enabling techniques to solidify a method to provide time- and condition-dependent risks by integrating a conventional PSA model with condition monitoring and prognostics techniques. We will discuss how to integrate the results with frequency of initiating events (IEs) and probability of basic events (BEs). Two illustrative examples will be introduced: (1) how the failure probability of a passive system can be evaluated under different plant conditions and (2) how the IE frequency for a steam generator tube rupture (SGTR) can be updated in terms of operating time. We expect that the proposed model can take a role of annunciator to show the variation of core damage frequency (CDF) depending on operational conditions.

• Korean Journal of Clinical Laboratory Science
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• v.45 no.1
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• pp.5-8
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• 2013

In the specimen of free PSA in the low concentration, the result in % bias from our institution and comparable evaluation institution was -33.7% which is exceeded % bias ${\pm}20%$ ; however, it was the domestically allowable limit recommended by the laboratory accreditation commission for specimen at the low concentration. In this paper, the cause was accredited by instability of free PSA substance within the specimen, and the specimen stability test was performed according to CLSI documents GP29-A2. After the low and high concentration specimen were made, and rapidly cooled down in a deep freezer with $-30^{\circ}C$, serum of two concentrations was measured for 10 consecutive days with 3 times a day by Architect i2000 and observed a change in the mean value. As the results of two groups, there were changes in the established target value, and a change level was evaluated by calculating it with % bias. The low concentration specimen had no significant reduction until the 4 day lapse in cold storage. However, % bias were reduced by -17.5% from the 5 day lapse, by 21.5% after the 7 day lapse, and by -26.9% after the 9 day lapse. The frozen specimen had only intra-day variation for 10 days. In the high concentration specimen, bias began to show as -12.2% from the 3 day lapse in cold storage. There was reduction by -28.9% from the 5 day lapse, by -39% after the 7 day lapse, and by -42.9% after the 9 day lapse. In the frozen specimen, there was only intra-day variation like the low concentration specimen in cold storage.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.3
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• pp.1259-1275
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• 2015

Background: This study reviewed the published evidence as to how prostate cancer outcomes vary across geographical remoteness and area level disadvantage. Materials and Methods: A review of the literature published from January 1998 to January 2014 was undertaken: Medline and CINAHL databases were searched in February to May 2014. The search terms included terms of 'Prostate cancer' and 'prostatic neoplasms' coupled with 'rural health', 'urban health', 'geographic inequalities', 'spatial', 'socioeconomic', 'disadvantage', 'health literacy' or 'health service accessibility'. Outcome specific terms were 'incidence', 'mortality', 'prevalence', 'survival', 'disease progression', 'PSA testing' or 'PSA screening', 'treatment', 'treatment complications' and 'recurrence'. A further search through internet search engines was conducted to identify any additional relevant published reports. Results: 91 papers were included in the review. While patterns were sometimes contrasting, the predominate patterns were for PSA testing to be more common in urban (5 studies out of 6) and affluent areas (2 of 2), higher prostate cancer incidence in urban (12 of 22) and affluent (18 of 20), greater risk of advanced stage prostate cancer in rural (7 of 11) and disadvantaged (8 of 9), higher survival in urban (8 of 13) and affluent (16 of 18), greater access or use of definitive treatment services in urban (6 of 9) and affluent (7 of 7), and higher prostate mortality in rural (10 of 20) and disadvantaged (8 of 16) areas. Conclusions: Future studies may need to utilise a mixed methods approach, in which the quantifiable attributes of the individuals living within areas are measured along with the characteristics of the areas themselves, but importantly include a qualitative examination of the lived experience of people within those areas. These studies should be conducted across a range of international countries using consistent measures and incorporate dialogue between clinicians, epidemiologists, policy advocates and disease control specialists.

• Journal of Adhesion and Interface
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• v.17 no.3
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• pp.89-95
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• 2016

An environmentally friendly water-based pressure sensitive adhesive (PSA) was designed in an attempt to replace the solvent-based adhesive for dry lamination used in flexible food packaging films. Instead of using a low molecular weight surfactant, which may have variable material properties, a high molecular weight dispersant was used for emulsification. A polymeric nano-dispersant (PND) was synthesized using solution polymerization, and it was used as a micelle seed in the surfactant, resulting in the synthesis of a core/shell grafted acrylic adhesive. The shell and core exhibited different $T_g$ values, so that the initial adhesion strength and holding power were complemented by the film's flexibility, which is required to provide good adhesion of thin films. Results showed that the PSA designed in this study using the PND instead of traditional low molecular weight surfactant had adhesive properties applicable to the flexible packaging with appropriate tack.