• Journal of the Korean Society for Marine Environment & Energy
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• v.19 no.1
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• pp.18-24
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• 2016

Mineral carbonation is a technology for permanently storing carbon dioxide by reacting with metal oxides containing calcium and magnesium. In this study, we used sea water and alkaline industrial by-product such as paper sludge ash (PSA) for the storage of carbon dioxide through direct carbonation. We found the optimum conditions of both sea water content (mixing ratio of sea water and PSA) and reaction time required in the direct carbonation through various experiments using sea water and PSA. In addition, we compared the amounts of carbon dioxide storage with the cases when sea water and ultra-pure water were separately used as solvents in the direct carbonation with PSA. The amount of carbon dioxide storage was calculated by using both solid weight increase through the carbonation reaction and the contents of carbonate salts from thermal gravimetric analysis. PSA particle used in this study contained 67.2% of calcium. The optimum sea water content and reaction time in the carbonation reaction using sea water and PSA were 5 mL/g and 2 hours, respectively, under the conditions of 0.05 L/min flow rate of carbon dioxide injected at $25^{\circ}C$ and 1 atm. The amounts of carbon dioxide stored when sea water and ultra-pure water were separately used as solvents in the direct carbonation with PSA were 113 and $101kg\;CO_2/(ton\;PSA)$, respectively. The solid obtained through the carbonation reaction using sea water and PSA was composed of mainly calcium carbonate in the form of calcite and a small amount of magnesium carbonate. The solid obtained by using ultra-pure water, also, was found to be carbonate salt in the form of calcite.

• Nuclear Engineering and Technology
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• v.50 no.8
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• pp.1234-1245
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• 2018

The risk of multi-unit nuclear power plants (NPPs) at a site has received considerable critical attention recently. However, current probabilistic safety assessment (PSA) procedures and computer code do not support multi-unit PSA because the traditional PSA structure is mostly used for the quantification of single-unit NPP risk. In this study, the main purpose is to develop a multi-unit Level 2 PSA method and apply it to full-power operating six-unit OPR1000. Multi-unit Level 2 PSA method consists of three steps: (1) development of single-unit Level 2 PSA; (2) extracting the mapping data from plant damage state to source term category; and (3) combining multi-unit Level 1 PSA results and mapping fractions. By applying developed multi-unit Level 2 PSA method into six-unit OPR1000, site containment failure probabilities in case of loss of ultimate heat sink, loss of off-site power, tsunami, and seismic event were quantified.

• Asian Pacific Journal of Cancer Prevention
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• v.17 no.6
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• pp.2941-2946
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• 2016

Background: The limitations of total serum PSA values remain problematic, especially after an initial negative prostate biopsy. In this prospective study of Chilean men with a continued suspicion of prostate cancer due to a persistently elevated total serum PSA, abnormal digital rectal examination and initial negative prostate biopsy were compared with the use of the on-line Chun nomagram, detection of primary malignant circulating prostate cells (CPCs) and free percent PSA to predict a positive second prostate biopsy. We hypothesized that men negative for circulating prostate cells have a small risk of clinically significant prostate cancer and thus may be conservatively observed. Men positive for circulating prostate cells should undergo biopsy to confirm prostate cancer. Materials and Methods: Consecutive men with a continued suspicion of prostate cancer underwent 12 core TRUS prostate biopsy; age, total serum PSA and percentage free PSA and Chun nomagram scores were registered. Immediately before biopsy an 8ml blood simple was taken to detect primary mCPCs. Mononuclear cells were obtained by differential gel centrifugation and identified using double immunostaining with anti-PSA and anti-P504S. Biopsies were classifed as cancer/no-cancer, mCPC detecton test as negative/positive and the total number of cells/8ml registered. Areas under the curve (AUC) for percentage free PSA, Chun score and CPCs were calculated and compared. Diagnostic yields were calculated with reference to the number of possible biopsies that could be avoided and the number of clinically significant cancers that would be missed. Results: A total of 164 men underwent a second biopsy; 41 (25%) had cancer; the AUCs were 0.65 for free PSA, 0.76 for the Chun score and 0.87 for CPC detection, the last having a significantly superior prediction value (p=0.01). Using cut off values of free PSA <10%, Chun score >50% and ${\geq}1$ CPC detected, CPC detection had a higher diagnostic yield. Some 4/41 cancers complied with the criteria for active surveillance, free PSA and the Chun score missed a higher number of significant cancers when compared with CPC detection. Conclusions: Primary CPC detection outperformed the use of free PSA and the Chun nomagram in predicting clinically significant prostate cancer at repeat prostate biopsy.

• Polymer(Korea)
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• v.35 no.4
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• pp.363-369
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• 2011

To study the effect of incorporation of a surface crosslinking layer on a crosslinked poly (sodium acrylate) (cPSA) absorbent with ethylene glycol dimethacrylate CEGDMA), we synthesized several surface crosslinked cPSAs with EGDMA by an inverse emulsion polymerization method to delay the absorption of excess water in concrete, Liquid paraffin was used as a continuous phase. cPSA was synthesized with acrylic acid (AA) neutralized with aqueous 8 M sodium hydroxide solution as a monomer, N,N-methylene bisacrylamide (MBA) as crosslinking agent and ammonium persulfate (APS) and sodium metabisulfite (SMBS) as a redox initiator system by inverse emulsion polymerization. FTIR spectroscopy was used to characterize $Ca^{2+}$ ion interaction with cPSA and cPSA-EGDMAs. The swelling ratios of synthesized absorbents were evaluated from the absorption in deionized water, cement saturated aqueous solution and aqueous solution of calcium hydroxide (pH 12). Equilibrium swelling times for cPSA and surface crosslinked cPSA with EGDMA were 2 and 3 hrs, respectively. We also observed an increase in setting time of the cement and an increase in the compressive strength of mortar by addition of the synthesized cPSA-EGDMA.

• Nuclear Engineering and Technology
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• v.43 no.3
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• pp.271-278
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• 2011

When performing fire PSA in a nuclear power plant, an event mapping method, using an internal event PSA model, is widely used to reduce the resources used by fire PSA model development. Feasible initiating events and component failure events due to fire are identified to transform the fault tree (FT) for an internal event PSA into one for a fire PSA using the event mapping method. A surrogate event or damage term method is used to condition the FT of the internal PSA. The surrogate event or the damage term plays the role of flagging whether the system/component in a fire compartment is damaged or not, depending on the fire being initiated from a specified compartment. These methods usually require explicit states of all compartments to be modeled in a fire area. Fire event scenarios, when using explicit identification, such as surrogate or damage terms, have two problems: (1) there is no consideration of multiple fire propagation beyond a single propagation to an adjacent compartment, and (2) there is no consideration of simultaneous fire propagations in which an initiating fire event is propagated to multiple paths simultaneously. The present paper suggests a fire propagation equation to identify all possible fire event scenarios for an explicitly treated fire event scenario in the fire PSA. Also, a method for separating fire events was developed to make all fire events a set of mutually exclusive events, which can facilitate arithmetic summation in fire risk quantification. A simple example is given to confirm the applicability of the present method for a $2{\times}3$ rectangular fire area. Also, a feasible asymptotic approach is discussed to reduce the computational burden for fire risk quantification.

• Journal of the Korean Society of Safety
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• v.27 no.5
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• pp.229-234
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• 2012

Operator's action time is evaluated from MAAP4 analysis used in conventional probabilistic safety assessment(PSA) of a nuclear power plant. MAAP4 code which was developed for severe accident analysis is too conservative to perform a realistic PSA. A best-estimate code such as RELAP5/MOD3, MARS has been used to reduce the conservatism of thermal hydraulic analysis. In this study, operator's action time of core cooling recovery operation is evaluated by using the MARS code, which its Fussell-Vessely(F-V) value was evaluated as highly important in a small break loss of coolant(SBLOCA) event and loss of component cooling water(LOCCW) event in previous PSA. The main conclusions were elicited : (1) MARS analysis provides larger time window for operator's action time than MAAP4 analysis and gives the more realistic time window in PSA (2) Sufficient operator's action time can reduce human error probability and core damage frequency in PSA.

• Journal of the Korean Society of Safety
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• v.34 no.3
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• pp.102-110
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• 2019

This paper describes the work and results of the preliminary Probabilistic Safety Assessment (PSA) for a research reactor in the design phase. This preliminary PSA was undertaken to assess the level of safety for the design of a research reactor and to evaluate whether it is probabilistically safe to operate and reliable to use. The scope of the PSA described here is a Level 1 PSA which addresses the risks associated with core damage. After reviewing the documents and its conceptual design, eight typical initiating events are selected regarding internal events during the normal operation of the reactor. Simple fault tree models for the PSA are developed instead of the detailed model at this conceptual design stage. A total of 32 core damage accident sequences for an internal event analysis were identified and quantified using the AIMS-PSA. LOCA-I has a dominant contribution to the total CDF by a single initiating event. The CDF from the internal events of a research reactor is estimated to be 7.38E-07/year. The CDF for the representative initiating events is less than 1.0E-6/year even though conservative assumptions are used in reliability data. The conceptual design of the research reactor is designed to be sufficiently safe from the viewpoint of safety.

• Korean Journal of Clinical Laboratory Science
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• v.41 no.2
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• pp.76-82
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• 2009

It would be one of the most important tests that determination of semen in crime scene as a matter of significant evidences. Recently, it has been developed for the identification of semen in forensic specimens which was used simply, easily and reproductively. In this study, Prostate-Specific-Antigen (PSA) Rapid Test kit was evaluated for the forensic identification of semen and compared with one step semen inspection forensic rapid test kit. The sensitivity and specificity of the rapid PSA kit were examined in addition to the stability of PSA. The positive band of rapid PSA kit shown even with 1,000,000-fold diluted semen, which was at least 100 timed higher than qualitative one step semen inspection forensic rapid test kit. PSA was detected in urine from normal male adult, however, it was not detected in urine from young boys and female body fluids. It was shown that PSA was very stable to resist boiling for 20 minutes and the effect of bacteria. In crime scene investigation, rapid PSA kit is expected to help to identify semen easily in the evidences.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.2
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• pp.601-606
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• 2015

Background: Prostate cancer is predominately a disease of older men, with a median age of diagnosis of 68 years and 71% of cancer deaths occurring in those over 75 years of age. While prostate cancer screening is not recommended for men >70 years, fit elderly men with controlled comorbidities may have a relatively long life expectancy. We compare the use of age related PSA with the detection of primary malignant circulating prostate cells mCPCs to detect clinically significant PC in this population. Materials and Methods: All men undergoing PC screening with a PSA >4.0ng/ml underwent TRUS 12 core prostate biopsy (PB). Age, PSA, PB results defined as cancer/no-cancer, Gleason, number of positive cores and percentage infiltration were registered. Men had an 8ml blood sample taken for mCPC detection; mononuclear cells were obtained using differential gel centrifugation and mCPCs were identified using immunocytochemistry with anti-PSA and anti-P504S. A mCPC was defined as a cell expressing PSA and P504S; a positive test as at least one mCPC detected/sample. Diagnostic yields for subgroups were calculated and the number of avoided PBs registered. Esptein criteria were used to define small grade tumours. Results: A total of 610 men underwent PB, 398 of whom were aged <70yrs. Men over 70 yrs had: a higher median PSA, 6.24ng/ml versus 5.59ng/ml (p=0.04); and a higher frequency of cancer detected 90/212 (43%) versus 134/398 (34%) (p=0.032). Some 34/134 cancers in men <70yrs versus 22/90 (24%) of men >70yrs complied with criteria for active surveillance. CPC detection: 154/398 (39%) men <70yrs were CPC (+), specificity for cancer 86%, sensitivity 88%, 14/16 with a false (-) result had a small low grade PC. In men >70 years, 88/212 (42%) were CPC (+); specificity 92%, sensitivity 87%, 10/12 with a false (-) had small low grade tumours. False (+) results were more common in younger men 36/154 versus 10/88 (p<0.02). With a PSA cutoff of 6.5ng/ml, in men <70yrs, 108 PB would be avoided, missing 56 cancers of which 48 were clinically significant. Using CPC detection, 124 biopsies would be avoided, missing only 2 clinically significant cancers. In men >70 yrs using a PSA >6.5ng/ml would have resulted in 108 PB with 34 PC detected, of which 14(41%) were small low grade tumours. Conclusions: The use of CPC detection in the fit elderly significantly decreases the number of PBs without missing clinically significant cancers, indicating superiority to the use of age-related PSA.

• Journal of the Korean Society of Safety
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• v.35 no.3
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• pp.86-95
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• 2020

This paper describes the work and the results of the final Probabilistic Safety Assessment (PSA) for the Jordan Research and Training Reactor (JRTR). This final PSA was undertaken to assess the level of safety for the design of a research reactor and to evaluate whether it is probabilistically safe to operate and reliable to use. The scope of the PSA described here is a Level 1 PSA, which addresses the risks associated with core damage. After reviewing the documents and its conceptual design, nine typical initiating events were selected regarding internal events during the normal operation of the reactor. AIMS-PSA (Version 1.2c) was used for the accident quantification, and FTREX was used as the quantification engine. 1.0E-15/yr of the cutoff value was used to deliminate the non-effective Minimal Cut Sets (MCSs) when quantifying the JRTR PSA model. As a result, the final result indicates a point estimate of 2.02E-07/yr for the overall Core Damage Frequency (CDF) attributable to internal initiating events in the core damage state for the JRTR. A Loss of Primary Cooling System Flow (LOPCS) is the dominant contributor to the total CDF by a single initiating event (9.96E-08/yr), and provides 49.4% of the CDF. General Transients (GTRNs) are the second largest contributor, and provide 32.9% (6.65E-08/yr) of the CDF.