• Nuclear Engineering and Technology
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• 제54권8호
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• pp.2771-2782
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• 2022

When assessing the radiological consequences of postulated accident scenarios, it is of primary interest to determine the amount of radioactive fission gas accumulated in the fuel rod free volume. The state-of-the-art semi-empirical approach (ANS 5.4-2010) is reviewed and compared with a mechanistic approach to evaluate the release of radioactive fission gases. At the intra-granular level, the diffusion-decay equation is handled by a spectral diffusion algorithm. At the inter-granular level, a mechanistic description of the grain boundary is considered: bubble growth and coalescence are treated as interrelated phenomena, resulting in the grain-boundary venting as the onset for the release from the fuel pellets. The outcome is a kinetic description of the release of radioactive fission gases, of interest when assessing normal and off-normal conditions. We implement the model in SCIANTIX and reproduce the release of short-lived fission gases, during the CONTACT 1 experiments. The results show a satisfactory agreement with the measurement and with the state-of-the-art methodology, demonstrating the model soundness. A second work will follow, providing integral fuel rod analysis by coupling the code SCIANTIX with the thermo-mechanical code TRANSURANUS.

• 한국화재소방학회:학술대회논문집
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• 한국화재소방학회 1996년도 학술발표회
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• pp.53-56
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• 1996

In order to propose the method of the consequence analysis for fire accidents by the heavy gas release and to obtain optimum conditions of parameter selections, the consequence analysis for jet fire by the accident of xylene vapor release were performed. And the effect and the sensitivity analysis of parameters affecting the consequence were investigated. Simulation results showed that important parameters affecting results of the xylene vapor release accident were mainly hole diameter, interested distance, wind speed, and so on. For the jet fire, the accident result and the sensitivity of thermal radiation were increased with the decrease of interested distance and the increase of hole diameters, and the accidental result was increased as the increase wind speed, but the sensitivity of thermal radiation was decreased.

• 한국안전학회지
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• 제18권1호
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• pp.64-70
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• 2003

For the unconfined vapor cloud explosion(UVCE) accident by the continuous release of gas-liquid flow of various saturated liquids in a vessel at ground level, overpressures were estimated by TNT equivalency model with two estimation methods, such as UVCE I model based on a constant release time and UVCEII model based on a real travel time of vapor by dispersion and analyzed with various release conditions. As a simulation result the simple, easy, and correct method of evaluation of consequences of the UVCE accident was proposed by using consequences of UVCE I model and correlation equations for differences of overpressures between UVCE models, so that this evaluation method could be used easily in the small and medium size enterprises without using the dispersion model.

• 대한안전경영과학회지
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• 제9권3호
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• pp.21-27
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• 2007

This paper analyses the effect of parameters on the consequences of the unconfined vapor cloud explosion accident (UVCE) by the release of heavy gas (xylene vapor). Simulation results showed that the overpresure was increased with the increase of the release hole diameter and with the decrease of the interested distance and the wind speed. While, the overpresure was not nearly affected by the release height, weather and environmental conditions. From the results of the consequence analysis and analysis of affecting the consequences of UVCE, the emergency plan should be established taking into account these parameters.

• 한국물환경학회지
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• 제21권6호
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• pp.595-601
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• 2005

In this research, effects of water circulation on phosphorus release from sediment into water body were studied. Sediments sampled at the Daechung Lake were used for the column experiments with circulation and non-circulation conditions. Deaeration coefficient, $K_1$ and reaeration coefficient, $K_2$ of non-circulation condition were 0.133 and 0, respectively, while $K_1$ and $K_2$ for circulation condition were 0.46 and 0.018, respectively. Oxidation Reduction Potential (ORP) showed a linear relationship with dissolved oxygen (DO) when DO is over 2 mg/L. Phosphorus concentration induced by phosphorus release from sediment was highly dependent upon DO, ORP, and pH. Under anaerobic condition, phosphorus release rate was higher for $Fe^{2+}$-bounded phosphorus compared to that of $Ca^{2+}$-bounded phosphorus.

• 대한기계학회논문집A
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• 제24권9호
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• pp.2174-2183
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• 2000

In this paper, the evaluation method of interfacial fracture toughness to apply the fracture toughness was investigated in adhesively bonded joints of AI/Ced./A1. Four types of adhesively bonded double-cantilever beam(DCB) joints with the interface crack were prepared for the test of interfacial fracture toughness. The experiments to measure the interfacial fracture toughness were performed under the various mixed-mode conditions. The critical energy release rate, Gc, was obtained by the experimental measurement of compliances. From the experimental results, the interfacial fracture toughness for the mixed-mode specimens is well characterized by the energy release rate, and the method of strength evaluation by the interfacial fracture toughness was discussed in adhesively bonded joints.

• 환경위생공학
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• 제17권1호
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• pp.75-80
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• 2002

This study was carried out to investigate release characteristics of phosphorus with DO, pH and temperature, to suppose its behaviour with time using mathematical model, and to under-stand its forms with pH. Released SRP was in inversely proportional to DO and it did few release in initial aerobic conditions, but it did actively with decreasing DO concentration. Also, its release was increased with increasing pH and temperature. It was found that relation between time and released SRP concentration was zero order reaction. As compared with k values in various pH and temp., they was $k_{15}>k_{25}$ in pH 6 but was $k_{15} in pH 7 and 8. Considering forms of phosphorus with pH, Resdi.-P & NAI-P increased but Ads.-P & Apt.-P decreased with increasing pH.

• 한국자동차공학회논문집
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• 제4권1호
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• pp.147-154
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• 1996

An one-zone heat release analysis was studied for a 6 cylinder direct injetction compressionignition engine. The heat transfer constants in this anlysis were calibrated to match the measured fuel energy at 1,000 rpm full load, which was the fuel mass multiplied by the fuel's heating value. The integrated gross heat release values were close to the measured fuel energy at various full load operating conditions. The combustion inefficiency from this calculation was proportional to the smoke of exhaust gas.

• Archives of Pharmacal Research
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• 제23권4호
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• pp.385-390
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• 2000

To demonstrate the effect of formulation conditions on the controlled release of protein from poly(lactide-co-glycolide) (PLGA) microspheres for use as a parenteral drug carrier, ovalbumin (OVA) microspheres were prepared using the W/O/W multiple emulsion solvent evaporation and extraction method. Methylene chloride or ethyl acetate was applied as an organic phase and poly(vinyl alcohol) as a secondary emulsion stabilizer. Low loading efficiencies of less than 20％ were observed and the in vitro release of OVA showed a burst effect in all batches of different microspheres, followed by a gradual release over the next 6 weeks. Formulation processes affected the size and morphology, drug content, and the controlled release of OVA from PLGA microspheres.

• 대한수의학회지
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• 제36권2호
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• pp.327-335
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• 1996

Recently in spite of the interest on the regulation of intracellular $Mg^{2+}$ by neurotransmitters or drugs, the magnesium ion($Mg^{2+}$) regulation by ${\alpha}_1$-adrenoceptor stimulation has not been studied in the heart yet. To elucidate the regulation of ${\alpha}_1$-adrenoceptor stimulation-induced $Mg^{2+}$ release and the effects of ${\alpha}_1$-adrenoceptor stimulation on pathophysiological conditions, in this study we have evaluated the effects of phenylephrine, PMA, $H_7$. staurosporine, verapamil and lidocaine on $Mg^{2+}$ release in perfused guinea pig heart. During preperfusion exogenous $Mg^{2+}$ was added to the medium to give 1.2mM 15min before starting to addition of drugs, and then the infusion of exogenous $Mg^{2+}$ was stopped. $Mg^{2+}$ in the perfusate leaving the heart was measured by atomic absorption spectrophotometry. $Mg^{2+}$ free solution produced an increase in heart rate and phenylephrine elicited $Mg^{2+}$ release from the heart. $Mg^{2+}$ release by phenylephrine was abolished by combined treatment with prazosin. By contrast, cardiac $Mg^{2+}$ uptake induced by a protein kinase C(PKC) activator, PMA was abolished by a selective PKC inhibitor, staurosporine. And the phenylephrine-induced $Mg^{2+}$ release was not affected by the PKC inhibitor, $H_7$. When verapamil or lidocaine was added to perfusing solution, $Mg^{2+}$ release was potentiated by phenylephrine from perfused guinea pig heart. These results suggest that ${\alpha}_1$-adrenoceptor stimulation caused $Mg^{2+}$ release and that PKC is not involved in ${\alpha}_1$-adrenoceptor mediated $Mg^{2+}$ release from perfused guinea pig heart. Under pathophysiological conditions, the $Mg^{2+}$ alteration by ${\alpha}_1$-adrenoceptor stimulation is considerable.