• Transactions of the Korean hydrogen and new energy society
• /
• v.27 no.6
• /
• pp.628-635
• /
• 2016

Natural gas reformed hydrogen is used as a fuel of fuel cell vehicle, PSA process is used for the purification of reformed hydrogen. In this study, the performance of CO adsorbent in PSA process was evaluated. Zeolite adsorbents used in the commercial PSA process is used. The physical and chemical properties of adsorbents were characterized using BET apparatus, XRD, and FE-SEM. The breakthrough apparatus modified from GC was used for the CO breakthrough experiment, the quantitative analysis of CO adsorption capacity was performed using CO breakthrough curve. Zeolite 10X and 13X showed superior CO adsorption capacity than activated alumina. The CO adsorption capacity of zeolite 10X is more than twice of zeolite 13X even the BET surface area is low. It seems that the presence of $Ca^{2+}$ cation in zeolite 10X is beneficial to the adsorption of CO.

• Journal of the Korean Society of Safety
• /
• v.14 no.1
• /
• pp.177-184
• /
• 1999

PSA(Probabilistic Safety Assessment) methodology is widely used on assessing the safety of Nuclear Power Plants(NPPs) quantitatively in the domestic nuclear field. Initiating event frequencies are absolutely needed to conduct PSA, and they considerably affect PSA results. There is no domestic database where domestic trip event cases are reflected, so they are used to assess the safety of NPPs that are from the foreign database. In this paper, operating experience data from the Korean NPPs was collected and analyzed for the trip event cases, which are necessary to determine the initiating events and their frequencies. Korean NPPs have experienced five of 16 initiating events, which we LOFW. LOCV, LOCCW, LOOP and GTRN as a result of analyzing the trip event cases. Initiating frequencies based on the domestic trip event cases are analyzed, and they are similar to that from the foreign database.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
• /
• 2009.05a
• /
• pp.412-415
• /
• 2009

This paper analyzes efficiency of photovoltaic(PV) tracking system using position solar algorithm(PSA). Solar location tracking system is needed for efficiently and intensively using PV system independent of environmental condition. PV tracking system of program method is presented a high tracking accuracy without the wrong operating in rapidly changed insolation by the clouds and atmospheric condition. Therefore, this paper analyzes efficiency of PV system using PSA algorithm for more correct position tracking of solar. Also, controlled altitude angle and azimuth angle by applied algorithm is compared with data of korea astronomy observatory. And this paper analyzes the tracking error and roves the validity of applied algorithm.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.36 no.4
• /
• pp.273-282
• /
• 2023

Probabilistic safety assessment (PSA) has been widely used to evaluate the seismic risk of nuclear power plants (NPPs). However, studies on seismic PSA for process plants, such as gas plants, oil refineries, and chemical plants, have been scarce. This is because the major disasters to which these process plants are vulnerable include explosions, fires, and release (or dispersion) of toxic chemicals. However, seismic PSA is essential for the plants located in regions with significant earthquake risks. Seismic PSA entails probabilistic seismic hazard analysis (PSHA), event tree analysis (ETA), fault tree analysis (FTA), and fragility analysis for the structures and essential equipment items. Among those analyses, ETA can depict the accident sequence for core damage, which is the worst disaster and top event concerning NPPs. However, there is no general top event with regard to process plants. Therefore, PSA cannot be directly applied to process plants. Moreover, there is a paucity of studies on developing fragility curves for various equipment. This paper introduces PSA for gas plants based on FTA, which is then transformed into Bayesian network, that is, a probabilistic graph model that can aid risk-informed decision-making. Finally, the proposed method is applied to a gas plant, and several decision-making cases are demonstrated.

• Nuclear Engineering and Technology
• /
• v.52 no.10
• /
• pp.2238-2249
• /
• 2020

In a seismic PSA, dependency among seismic failures of components has not been explicitly modeled in the fault tree or event tree. This dependency is separately identified and assigned with numbers that range from zero to unity that reflect the level of the mutual correlation among seismic failures. Because of complexity and difficulty in calculating combination probabilities of correlated seismic failures in complex seismic event tree and fault tree, there has been a great need of development to explicitly model seismic correlation in terms of seismic common cause failures (CCFs). If seismic correlations are converted into seismic CCFs, it is possible to calculate an accurate value of a top event probability or frequency of a complex seismic fault tree by using the same procedure as for internal, fire, and flooding PSA. This study first proposes a methodology to explicitly model seismic dependency by converting correlated seismic failures into seismic CCFs. As a result, this methodology will allow systems analysts to quantify seismic risk as what they have done with the CCF method in internal, fire, and flooding PSA.

• Journal of Science and Technology Studies
• /
• v.13 no.1
• /
• pp.77-109
• /
• 2013

The global diffusion of Evidence-Based Medicine (EBM) is changing the landscape of medicine and the healthcare system. STS scholars have shown how EBM works when put into practice. In continuing to add to the literature of previous scholars, this paper traces the historical process and debate over Prostate-Specific Antigen (PSA) testing as an early screening test for prostate cancer in the U.S. This study will reveal that both pros and cons of the testing using EBM as a crucial resources of the debate, and in the process both 'flexibly' interpret and mobilize the hierarchy of scientific evidence for EBM despite the fact the hierarchy is imagined to being scientific criteria that is rigid. Furthermore, this paper will argue that this phenomenon, for which EBM currently seems to support the cons side of PSA screening, was constructed in the context of appraisal of the value 'quality of life' in the EBM system. This case study proposes that those who study the debate of medical technology in the EBM era should contextualize and analyze EBM as part of this debate rather than simply taking EBM for granted.

• Asian Pacific Journal of Cancer Prevention
• /
• v.15 no.7
• /
• pp.3087-3091
• /
• 2014

Purpose: To determine the utility of digital rectal examination (DRE), serum total prostate specific antigen (tPSA) estimation, and transrectal ultrasound (TRUS) for the detection of prostate cancer (PCa) in men with lower urinary tract symptoms (LUTS). Materials and Methods: All patients with abnormal DRE, TRUS, or serum tPSA >4ng/ml, in any combination, underwent TRUS-guided needle biopsy. Eight cores of prostatic tissue were obtained from different areas of the peripheral prostate and examined histopathologically for the nature of the pathology. Results: PCa was detected in 151 (50.3%) patients, remaining 149 (49.7%) showed benign changes with or without active prostatitis. PCa was detected in 13 (56.5%), 9 (19.1%), 26 (28.3%), and 103 (74.6%) of patients with tPSA <4 ng/ml, 4-10 ng/ml, 10-20 ng/ml and >20 ng/ml respectively. Only 13 patients with PCa had abnormal DRE and TRUS with serum PSA <4 ng/ml. The detection rate was highest in patients with tPSA >20 ng/ml. The association between tPSA level and cancer detection was statistically significant (p<0.01). Among 209 patients with abnormal DRE and raised serum PSA, PCa was detected in 128 (61.2%). Conclusions: The incidence of PCa increases with increasing serum level of tPSA. The overall screening and detection rate can be further improved by using DRE, TRUS and TRUS-guided prostate needle biopsies.

• Journal of Adhesion and Interface
• /
• v.9 no.3
• /
• pp.27-33
• /
• 2008

A series of aluminum acetylacetonate (AlACA) belonging in inorganic chelate calculating with the ratio of -COOH mole in PSA (0, 0.25, 0.5, 0.75, 1) and a series of PSA with different acrylic acid contents (3 wt%, 7 wt%, 10 wt%) were blended and measured gel contents, probe tack, peel strength, SAFT. With the increasing of aluminum acetylacetonate contents, the network structure was formed and gel contents were increased. Probe tack fibrillation and peel strength were decreased following the addition of aluminum acetylacetonate. SAFT were significantly changed with the change of acrylic acid contents in PSA. From these results, aluminum acetylacetonate could be used in the range of which would not change the performance a lot, and cure the PSA.

• Proceedings of the Korean Nuclear Society Conference
• /
• 2004.10a
• /
• pp.503-504
• /
• 2004

• Proceedings of the Korean Nuclear Society Conference
• /
• 2003.05a
• /
• pp.195.1-195.1
• /
• 2003