• Electrical & Electronic Materials
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• v.9 no.9
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• pp.891-899
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• 1996

A model for predicting the characteristics of elastic ferromagnetic materials having a moving gap was presented. Based on the model parameters concerning behavior of material, such as the instantaneous field intensity, attractive force between the poles, length of gap, and the induced current/ emf in the circuit can be determined from the numerical integrations of the governing equations derived. From the results of the model it is found that when dc emf is imposed on the circuit the current sharply rise and fall for very short duration then stabilize at extremely low level which depends mainly on elasticity, permeabilities and ratio of resistivity. Subsequently output emf is shown stabilized at constant value which depends on the previous parameters as well as the resistivity ratio of primary to secondary circuit after sufficient progress of time.

• Wind and Structures
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• v.12 no.5
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• pp.413-424
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• 2009

A series of wind tunnel free-decay sectional model dynamic tests were conducted to examine the effects of torsional-to-vertical natural frequency ratio of 2DOF bridge dynamic systems on the aerodynamic and dynamic properties of bridge decks. The natural frequency ratios tested were around 2.2:1 and 1.2:1 respectively, with the fundamental vertical natural frequency of the system held constant for all the tests. Three 2.9 m long twin-deck bridge sectional models, with a zero, 16% (intermediate gap) and 35% (large gap) gap-to-width ratio, respectively, were tested to determine whether the effects of frequency ratio are dependent on bridge deck cross-section shapes. The results of wind tunnel tests suggest that for the model with a zero gap-width, a model to approximate a thin flat plate, the flutter derivatives, and consequently the aerodynamic forces, are relatively independent of the torsional-to-vertical frequency ratio for a relatively large range of reduced wind velocities, while for the models with an intermediate gap-width (around 16%) and a large gap-width (around 35%), some of the flutter derivatives, and therefore the aerodynamic forces, are evidently dependent on the frequency ratio for most of the tested reduced velocities. A comparison of the modal damping ratios also suggests that the torsional damping ratio is much more sensitive to the frequency ratio, especially for the two models with nonzero gap (16% and 35% gap-width). The test results clearly show that the effects of the frequency ratio on the flutter derivatives and the aerodynamic forces were dependent on the aerodynamic cross-section shape of the bridge deck.

• Nuclear Engineering and Technology
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• v.52 no.12
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• pp.2760-2770
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• 2020

A model for calculation of fuel temperature profile using binary gas mixture of Helium and Xenon for gap gas conductance is proposed here. In this model, the temperature profile of a fuel pencil from fuel centreline to fuel surface has been calculated by taking into account the dilution of Helium gas filled during fuel manufacturing due to accumulation of fission gas Xenon. In this model an explicit calculation of gap gas conductance of binary gas mixture of Helium and Xenon has been carried out. A computer code Fuel Characteristics Calculator (FCCAL) is developed for the model. The phenomena modelled by FCCAL takes into account heat conduction through the fuel pellet, heat transfer from pellet surface to the cladding through the gap gas and heat transfer from cladding to coolant. The binary noble gas mixture model used in FCCAL is an improvement over the parametric model of Lassmann and Pazdera. The results obtained from the code FCCAL is used for fuel temperature calculation in 3-D neutron diffusion solver for the coolant outlet temperature of the core at steady operation at full power. It is found that there is an improvement in calculation time without compromising accuracy with FCCAL.

• Proceedings of the Korean Nuclear Society Conference
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• 1997.05a
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• pp.184-189
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• 1997

A prompt fission gas release model incorporating the resistance to gas flow in the gap was developed and the effects of gap resistance and failure location on prompt fission gas release from the cladding breach were assessed. The process of prompt fission gas release from the plenum and gap into the coolant was modeled in accordance with three major phenomena: (1) transient gas flow in the gap, (2) the growth of the fission gas bubble while it is still attached to the breach, and (3) the detachment of the fission gas bubble from the breach and mixing with the coolant. The cumulative mass release fraction by the present model was calculated for the case of Young-Gwang 3 & 4 nuclear fuel rod as a typical example. The results showed that the release behavior of prompt fission gas with time was different from the frictionless model which has frequently been used in a simplified approach, and that the location of cladding failure was another key factor for the prompt fission gas release process due to the resistance in the gap.

• Journal of Electrical Engineering and Technology
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• v.12 no.2
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• pp.769-777
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• 2017

The research of air gap flux density has a significant effect on predicting and optimizing the structure parameters of electrical machines. In the paper, the air gap coefficient, leakage flux factor and saturation coefficient are first analytically expressed in terms of motor properties and structure parameters. Subsequently, the analytical model of average air gap flux density for surface-mounted permanent magnet synchronous machines is proposed with considering slotting effect and saturation. In order to verify the accuracy of the proposed analytical model, the experiment and finite element analysis (FEA) are used. It shows that the analytical results keep consistency well with the experimental result and FEA results, and the errors between FEA results and analytical results are less than 5% for SPM with high power. Finally, the analytical model is applied to optimizing the motor structure parameters. The optimal results indicate that the analytical calculation model provides a great potential to the machine design and optimization.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.2
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• pp.157-166
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• 2014

A light water reactor (LWR) fuel rod consists of zirconium alloy cladding tube and uranium dioxide pellets with a slight gap between them. The modeling of heat transfer across the gap between fuel pellets and the protective cladding is essential to understanding fuel behavior under irradiated conditions. Many researchers have been developing fuel performance codes based on finite element method (FE) to calculate temperature, stress and strain for multidimensional analysis. The gap conductance model for multi-dimension is difficult issue in terms of convergence and nonlinearity because gap conductance is function of gap thickness which depends on mechanical analysis at each iteration step. In this paper, virtual link gap element (VLG) has been proposed to resolve convergence issue and nonlinear characteristic of multidimensional gap conductance. In terms of calculation accuracy and convergence efficiency, the proposed VLG model has been evaluated for variable cases.

• Transactions of Materials Processing
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• v.5 no.3
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• pp.232-238
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• 1996

A dynamic mill set-up technique was developed to achieva a more precise roll gap set-up of the finishing mill stands for steel strip rolling. In the conventional mill set-up model the set-up values such as roll gap and roll speed are determined before the sheet bar reached the entry side of the finishing mill train and maintained constant until the strip top end passes through the last stand. In the way however a dynamic set-up logic that gives a way to adjust the roll gap value of the final mill stand for the strip ingoing from the ahead of the front stand was developed and attached to the existing set-up model. The roll gap modification is based on the analysis of the observation in the third stand of the finishing mill train. The dynamic set-up model was proved very effective for the more precise mill set-up and for operational stability in the hot strip finishing mill train.

• International Journal of Quality Innovation
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• v.4 no.1
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• pp.116-130
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• 2003

The gap-based SERVQUAL model is a popular service quality determinant due to its superior diagnostic capacity over alternative explanatory frameworks. However, some researchers criticize the performance of the SERVQUAL model and propose alternative service Quality measurement constructs. Nevertheless, it is argued that the superior diagnostic capacity of SERVQUAL is its key strength; and that any criticism made of it when making comparison with alternative models does not reflect the differing nature of scales of statistical analysis. Arguably, the only limitation of a gap-based model is misinterpretation of customers' evaluation and perception of a service. In this research, the gap score is transformed into a ratio score. Also, empirical tests and implications are presented to support this alternative contribution to the body of knowledge.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.09a
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• pp.1343-1349
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• 2010

This paper presents the behavior of the soil based on the Gap Parameter during the Shield TBM tunnel excavation in sandy soil. This study reproduced the tunnel before and after the excavation according to the diameter of the tunnel, water ratio and depth to execute a Scaled Model Test and analyzed the behavior change of the upper soil. As a result, tunneling after for soil stress decreased was similar in all the Case. In addition, the soil stress decreased was in water ratio increases.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.05a
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• pp.888-893
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• 2004

This paper proposed a dual actuator using bimorph PZT for information storage device based on prove array NSOM(Near-field Scanning Optical Microscopy). The gap between the media and the optical head should be maintained within the optical tolerance. Therefore, a new actuator having high sensitivity is required. Bimorph PZT, which has fast access time and high sensitivity characteristic, is suitable for this precise actuating system. This paper is focused on derivation of mathematical model of dual bimorph PZT actuator and control algorithm. Hamilton's principle was used for mathematical model. The model is verified by FEA(Finite Element Analysis), and compared with experimental results. Different control algorithms were used f3r two bimorph PZT actuating same direction and opposite direction. The gap between recording media and optical head was controlled within 20nm in experiment.