• Nuclear Engineering and Technology
• /
• v.53 no.2
• /
• pp.509-521
• /
• 2021

In this paper, from a review of the size distribution of the bubbles during pool scrubbing obtained from experiments by EPRI, we apply the bubble size distributions to analyses on the decontamination factors of pool scrubbing via I-COSTA (In-Containment Source Term Analysis). We perform sensitivity studies of the bubble size on the various mechanisms of deposition of aerosol particles in pool scrubbing. We also perform sensitivity studies on the size distributions of the bubbles depending on the diameters at the nozzle exit, the molecular weights of non-condensable gases in the carrier gases, and the steam fractions of the carrier gases. We then perform analyses of LACE-ESPANA experiments and compare the numerical ~ results to those from SPARC-90 and experimental results in order to show the effect of the bubble size distributions.

• Journal of Environmental Health Sciences
• /
• v.46 no.2
• /
• pp.150-158
• /
• 2020

Objective: This study is designed to measure the concentration of DBPs (disinfection by-products) in pool water and in air and to estimate the carcinogenic potential through the evaluation of inhalation exposure. Methods: The subjects were six indoor swimming pools with many users in Gwangju. Samples of pool water and indoor air were taken every one month from August 2018 to August 2019 and analyzed for eight swimming pool standards. Three-liter air samples were collected and the VOCs were analyzed using GC/MS directly connected to thermal desorption. Results: pH was 6.8-7.5 and the concentration of free residual chlorine in pool water was 0.40-0.96 ?/ℓ. Physicochemical test items such as KMnO₄ consumption and heavy metal items such as Aluminum met existing pool hygiene standards. No VOC materials were detected except for the DBPs. The concentration of THMs in the pool water was 11.05-41.77 ㎍/L and the THMs mainly consist of Chloroform (63-97%) and BDCM (3-31%). The concentration of indoor air THMs is 13.24-32.48 ㎍/㎥ and consists of Chloroform. The results of carcinogenic assessment of chloroform in the indoor swimming pool via inhalation exposure were 2.0 to 6.4 times higher than the 'acceptable risk level' suggested by the US EPA. Conclusions: The concentration of THMs in the pool water is 11.05-41.77 ㎍/L, most of which is chloroform. In addition, the concentration of indoor air THMs is 13.24-32.48 ㎍/㎥. The result of carcinogenic assessment of chloroform was 2.0 to 6.4 times higher than the 'acceptable risk level' suggested by the US EPA.

• 제어로봇시스템학회:학술대회논문집
• /
• 1997.10a
• /
• pp.325-328
• /
• 1997

In this paper the modeling and control of a twin roll strip caster is investigated. Mathematical models for the strip casting process are obtained by analyzing five critical areas such that the molten steel level in the pool, solidification process, roll separating force and torque, roll dynamics including hydraulic actuators, and roll drive system. A two-level control strategy is proposed. At lower level, three local subsystems are independently feedback-controlled by suitable local controllers which perform well to the behaviors of each subsystem. They are a variable structure control of the molten steel level in the pool, an adaptive predictive control of the roll gap which is directly related to the strip thickness, and an $H^{\infty}$ control of the roll drive system. At higher level, all reference signals to the lower level subsystems are generated by an optimal controller in the perspective of regulating the strip thickness and roll separating force. Simulations are provided..

• Journal of Korean Society of Environmental Engineers
• /
• v.32 no.5
• /
• pp.517-522
• /
• 2010

The riffle and pool play an important role for composing river front, but very little information was used for river restoration considering flood control. In this paper extensive field investigation was carried out to estimate hydraulic processes in the pool. Furthermore diurnal stratification model was developed and applied to assess flow change in pool. The physical mechanism of water flow including diurnal processes was well simulated, the results show that diurnal variation of water flow in the pool about 2 m depth is governed by the level of mixing due to density flow. These effort will be useful to guide field data collection work and to understand primary production.

• Nuclear Engineering and Technology
• /
• v.55 no.8
• /
• pp.3102-3113
• /
• 2023

Following the Fukushima nuclear disaster, the simulation of accidents in the spent fuel pool has become more noticeable. Despite the low amount of decay heat power, the consequences of the accidents in a spent fuel pool (SFP) can be severe due to the high content of long-lived radionuclides and lack of protection by the pressure vessel. In this study, the loss-of-cooling accident (LOFA) for the VVER-1000/V446 spent fuel pool is simulated by employing RELAP5 and MELCOR 1.8.6 as the best estimate and severe accident analysis codes, respectively. For two cases with different total power levels, decay heat of spent fuels is calculated by ORIGEN-II code. For modeling SFP of a VVER-1000, a qualified nodalizations are considered in both codes. During LOFA in SFP, the key sequences such as heating up of the pool water, boiling and reducing the water level, uncovering the spent fuels, increasing the temperature of the spent fuels, starting oxidation process (generating Hydrogen and extra power), the onset of fuel melting, and finally releasing radionuclides are studied for both cases. The obtained results show a reasonable consistency between the RELAP5 and MELCOR codes, especially before starting the oxidation process.

• Journal of the Korean Association of Geographic Information Studies
• /
• v.9 no.2
• /
• pp.115-126
• /
• 2006

The purpose of this study is to develop an urban inundation model using GIS(geographic information system). The model is combining a storm sewer system model and a overland-flow model for the estimation inundation depth in urban area caused by the surcharge of storm sewers. SWMM(storm water management model) was employed to resolve the storm sewer flow and to provide the overflow hydrographs caused by the failure of a drainage system due to the shortage of drainage capacity. The level-pool overland-flow model and DEM based overland-flow model were used to calculate the detail inundation zones and depths due to the surcharge on overland surface. The simulation results can help the decision preventing flood damages by redesigning and enlarging the capacities of storm sewer systems in the inundation-prone areas. The model can also be applied to make the potential inundation area map and establish flood-mitigation measures as a part of the decision support system for flood control authority.

• Nuclear Engineering and Technology
• /
• v.51 no.1
• /
• pp.73-83
• /
• 2019

It is important to clarify the mechanisms of molten-fuel-pool sloshing behavior that might be encountered during a core disruptive accident of sodium-cooled fast reactors. In this study, motivated by acquiring some evidence for understanding the characteristics of this behavior at more realistic conditions, a number of experiments are newly performed by injecting nitrogen gas into a water pool with the accumulation of solid particles. To achieve comprehensive understanding, various parameters including particle bed height, particle size, density, shape, gas pressure along with the gas-injection duration, were employed. It is found that due to the different interaction mechanisms between solid particles and the gas bubble injected, three kinds of regimes, termed respectively as the bubble-impulsion dominant regime, the transitional regime and the bed-inertia dominant regime, could be identified. The performed analyses also suggest that under present conditions, all our experimental parameters employed can have noticeable impact on the regime transition and resultant sloshing intensity (e.g. maximum elevation of water level at pool peripheries). Knowledge and fundamental data from this work will be used for the future verifications of fast reactor severe accident codes in China.

• Journal of the Korea Safety Management & Science
• /
• v.13 no.2
• /
• pp.157-167
• /
• 2011

Currently, interest on physical distribution is increasing due to burden of oil cost increases as oil price rises day by day. As interest grows, there are number of studies have been conducting on saving the cost of distribution. On the other hand, number of study on service of distribution is insufficient. Actually, subject of service of physical distribution have been studied by number of survey organizations, research organizations and mass media. Although, configuration for each organization is different from each other and it is hard to measure objective satisfactory factor of customers. This means needs for constructing standardized measuring tool as well as research on measuring service quality of distribution is not active. Therefore, this research is to compare and analyze compatibility of service quality measuring using SERVQUAL and SERVPERF and trying to clarify differences affected by importance service quality by each level to actual service quality. Also, this research is to make basic and standardized measuring model to improve quality of physical distribution especially using analysis of service quality and customer satisfaction of pallet pool service which contributes rationalization of distribution and reduce the cost by standardizing specification and size of pallet, allowing sharing of pallet. To conduct this research, case study of a company A is used where it is in a pallet pool business. Using this example, the goal is to give help on pallet pool business a strategic exercise if the business by point out major factors that affect customer satisfaction by collecting customer assessment along with examination of SERVQUAL and SERVPERF in measuring service quality if pallet pool service.

• Journal of Veterinary Clinics
• /
• v.24 no.4
• /
• pp.603-607
• /
• 2007

The sample sizes required to detect at least one chicken infectious bronchitis virus(IBV) infection at flock-level were determined using pooled samples for 48 submissions with different samples in each. A total of serum samples of 9,980 layers from Kangwon, Chungpook and Chungnam province were collected and tested hemagglutination inhibition(HI) antibody titers against IBV both individually and with pooling size of 10. Of the 48 submissions, 72.9% were required less than 5 pools to detect at least one infected pool at 95% confidence level, and the corresponding rate was 77.1% at 90% confidence level. Overall, the number of pools was decreased as the percent of positive pools increased. At two different cut-of HI titer${\geq}9\;and{\geq}10$ for individual samples the seroprevalence was 50.1% and 33.4%, respectively while 59.9% were seropositive for pooled samples at HI $titer{\geq}8$. The correlation coefficients between pooled and individual samples at each submission were 0.592(p<0.001) for HI $titer{\geq}9$ and 0.561(p<0.001) for ${\geq}10$, with common correlation coefficient of 0.576. This study indicated that pooled testing for the detection of IBV infection may be an alternative strategy when only the pooled results are of interest and the prevalence has not known exactly.

• ALGAE
• /
• v.17 no.2
• /
• pp.89-93
• /
• 2002

Seasonal changes of pigment compositionin two intertidal red algae, Gloiopeltis furcata (Postels et Ruprecht) J. Agardh, and Porphyra yezoensis Ueda, were investigated. Chlorophyll α and phycoerythrin levels were high during winter, but decreased in late spring or summer, with accompanying discoloration from deep red to green or yellow. This discoloation corresponded closely to the fluctuationof phycoerythrin content. Nevertheless, photosynthesis capacity was maintained by the increasing water temperature in the field, suggesting that large amounts of phycoerythrin are not necessary for photosynthesis. Phycoerythrin conten correlated significantly with nitrogen content in both species when the nitrogen level was greater than the level of critical content (1.30% DW in G. furcata, and 2.26% DW in P. yezoensis), indicating that phycoerythrin plays a more important role in the nitrogen status as a nitrogen pool than that of nitrogen critical content. Furthermore, the dependence level of the alage on phycoerythrin as a nitrogen pool was greater in P. yezoensis than in G. furcata because of the remarkable increase of phycoerythrin content in P. yezoensis with increasing jnitrogen content.