• 한국수산과학회지
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• 제49권4호
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• pp.486-492
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• 2016

This study investigates the relationship between environmental factors, such as semilunar rhythm and atmospheric pressure, and the release of Marphysa sanguinea larvae. During artificial seed production in a temperature-regulated culture system, there was an increase in the number of released larvae at tide times between 3-4 and 9-11. Numbers of larvae released were significantly correlated with tidal rhythms. Atmospheric pressure also appeared to influence larval release, with increased numbers released when a period of high atmospheric pressure followed a period of low pressure.

• Nuclear Engineering and Technology
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• 제56권1호
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• pp.132-140
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• 2024

In the event of a severe accident in Sodium Cooled Fast Reactors (SFR), the sodium combustion aerosols along with fission product aerosols would migrate to the environment through leak paths of the Reactor Containment Building (RCB) concrete wall under positive pressure. Understanding the characteristics of sodium aerosol transport through concrete leak paths is important as it governs the environmental source term. In this context, experiments are conducted to study the influence of various parameters like pressure, initial mass concentration, leak path diameter, humidity etc., on the transport and deposition of sodium aerosols in straight leak paths of concrete. The leak paths in concrete specimens are prepared by casting and the diameter of the leak path is measured using thermography technique. Aerosol transport experiments are conducted to measure the transported and plugged aerosol mass in the leak paths and corresponding plugging times. The values of differential pressure, aerosol concentration and relative humidity taken for the study are in the ranges 10-15 kPa, 0.65-3.04 g/m³ and 30-90% respectively. These observations are numerically simulated using 1-Dimensional transport equation. The simulated values are compared with the experimental results and reasonable agreement among them is observed. From the safety assessment view of reactor, the approach presented here is conservative as it is with straight leak paths.

• Wind and Structures
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• 제25권6호
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• pp.589-608
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• 2017

A novel probabilistic approach is presented for estimating the equivalent static wind loads that produce a static response of the structure, which is "equivalent" in a probabilistic sense, to the extreme dynamic responses due to the unsteady pressure random field induced by the wind. This approach has especially been developed for complex structures (such as stadium roofs) for which the unsteady pressure field is measured in a boundary layer wind tunnel with a turbulent incident flow. The proposed method deals with the non-Gaussian nature of the unsteady pressure random field and presents a model that yields a good representation of both the quasi-static part and the dynamical part of the structural responses. The proposed approach is experimentally validated with a relatively simple application and is then applied to a stadium roof structure for which experimental measurements of unsteady pressures have been performed in boundary layer wind tunnel.

• Carbon letters
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• 제16권1호
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• pp.25-33
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• 2015

The prime objective of this research was to study the influence of hot-pressing pressure and matrix-to-reinforcement ratio on the densification of short-carbon-fiber-reinforced, randomly oriented carbon/carbon-composite. Secondary objectives included determination of the physical and mechanical properties of the resulting composite. The 'hybrid carbon-fiber-reinforced mesophase-pitch-derived carbon-matrix' composite was fabricated by hot pressing. During hot pressing, pressure was varied from 5 to 20 MPa, and reinforcement wt% from 30 to 70. Densification of all the compacts was carried at low impregnation pressure with phenolic resin. The effect of the impregnation cycles was determined using measurements of microstructure and density. The results showed that effective densification strongly depended on the hot-pressing pressure and reinforcement wt%. Furthermore, results showed that compacts processed at lower hot-pressing pressure, and at higher reinforcement wt%, gained density gradually during three densification cycles and showed the symptoms of further gains with additional densification cycles. In contrast, samples that were hot-pressed at moderate pressure and at moderate reinforcement wt%, achieved maximum density within three densification cycles. Furthermore, examination of microstructure revealed the formation of cracks in samples processed at lower pressure and with low reinforcement wt%.

• 한국막학회:학술대회논문집
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• 한국막학회 2002년도 춘계 총회 및 학술발표회
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• pp.23-31
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• 2002

No Abstract, See Full-text

• Food Science and Biotechnology
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• 제17권2호
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• pp.324-329
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• 2008

The effect of ultra-high pressure homogenization on the emulsifying properties of whey protein was investigated in a model emulsion made with whey protein isolate and soya oil under various pH. The emulsifying properties, the average diameter of the oil droplets ($d_{vs}$), and the protein load, were measured for each emulsion produced at different homogenization pressures (50 to 200 MPa) and pH values (4.6 to 8.0). According to the results of variance analysis and response surface, the pH had more influence on oil droplet size and protein load than homogenization pressure. The model equations, which were obtained by response surface analysis, show that pH and homogenization pressure had the major effect on oil droplet size and protein load. Higher homogenization pressure decreased the average droplet size and the protein load. Homogenization at high pressure, as opposed to low pressure, causes no overprocessing, but the effect was pH-dependent. The average diameter of the oil droplets increased slightly by decreasing the pH from 8.0 to 6.5 and then increased dramatically toward the isoelectric point of whey protein (i.e., at pH 4.6). Moreover associated droplets were found at acidic pH and their size was increased at high temperature.

• International Journal of Naval Architecture and Ocean Engineering
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• 제7권3호
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• pp.435-451
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• 2015

Evaluation of the performance of aging structures is essential in the oil and gas industry, where the inaccurate prediction of structural performance can have significantly hazardous consequences. The effects of structure failure due to the significant reduction in wall thickness, which determines the burst strength, make it very complicated for pipeline operators to maintain pipeline serviceability. In other words, the serviceability of gas pipelines and elbows needs to be predicted and assessed to ensure that the burst or collapse strength capacities of the structures remain less than the maximum allowable operation pressure. In this study, several positions of the corrosion in a subsea elbow made of API X42 steel were evaluated using both design formulas and numerical analysis. The most hazardous corrosion position of the aging elbow was then determined to assess its serviceability. The results of this study are applicable to the operational and elbow serviceability needs of subsea pipelines and can help predict more accurate replacement or repair times.

• Ocean Systems Engineering
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• 제8권1호
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• pp.57-77
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• 2018

The present paper deals with the finite element analysis of water tanks with rigid baffle. Fluid is discretized by two dimensional eight-node isoparametric elements and the governing equation is simulated by pressure based formulation to reduce the degrees of freedom in the domain. Both free vibration and force vibration analysis are carried out for different sizes and positions of block at tank bottom. The fundamental frequency depends on block height and it reduces with the increase of block height. The variation of hydrodynamic pressure on tank walls not only depends of the exciting frequency but also on the size and position of rigid block at tank bottom. The hydrodynamic pressure has higher value when the exciting frequency is equal and lower than the fundamental frequency of the water in the tank. Similarly, the hydrodynamic pressure increases with the increase of width of the block for all exciting frequencies when the block is at the centre of tank. The left and right walls of tank have experienced different hydrodynamic pressure when the block is placed at off-centre. However, the increase in hydrodynamic pressure on nearest tank wall becomes insignificant after a certain value of the distance between the wall and the rigid block.

• Wind and Structures
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• 제4권2호
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• pp.119-130
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• 2001

The paper addresses the suitability of wind pressure coefficients specified in contemporary design standards and codes of practice for gable roofs of intermediate slope (roof angle $10^{\circ}-30^{\circ}$). In a recent research study, a series of low building models with different roof slopes in this intermediate range were tested in a boundary layer wind tunnel under simulated open country terrain conditions. This was different from the original study in the 70's, which produced the current provisions on the basis of a model tested only for a single roof slope (4:12) in this range. The results of the study suggest that a modification to the American wind provisions would be warranted to make them more representative of the true local and area-averaged wind loads imposed on gable roofs of intermediate slope.

• Wind and Structures
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• 제36권6호
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• pp.393-404
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• 2023

Skewness and kurtosis are important higher-order statistics for simulating non-Gaussian wind pressure series on low-rise buildings, but their predictions are less studied in comparison with those of the low order statistics as mean and rms. The distribution gradients of skewness and kurtosis on roofs are evidently higher than those of mean and rms, which increases their prediction difficulty. The conventional artificial neural networks (ANNs) used for predicting mean and rms show unsatisfactory accuracy in predicting skewness and kurtosis owing to the limited capacity of shallow learning of ANNs. In this work, the deep neural networks (DNNs) model with the ability of deep learning is introduced to predict the skewness and kurtosis on a low-rise building. For obtaining the optimal generalization of the DNNs model, the hyper parameters are automatically determined by Bayesian Optimization (BO). Moreover, for providing a benchmark for future studies on predicting higher order statistics, the data sets for training and testing the DNNs model are extracted from the internationally open NIST-UWO database, and the prediction errors of all taps are comprehensively quantified by various error metrices. The results show that the prediction accuracy in this study is apparently better than that in the literature, since the correlation coefficient between the predicted and experimental results is 0.99 and 0.75 in this paper and the literature respectively. In the untrained cornering wind direction, the distributions of skewness and kurtosis are well captured by DNNs on the whole building including the roof corner with strong non-normality, and the correlation coefficients between the predicted and experimental results are 0.99 and 0.95 for skewness and kurtosis respectively.