• 한국전산유체공학회:학술대회논문집
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• 2001.10a
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• pp.118-125
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• 2001

The performance prediction of SMART MCP was performed using a computational fluid dynamics code. General capacity-head performance curve of MCP, which is provided to other design branches as design input, was obtained and it showed the typical type of axial pump performance curve. When four MCPs operate in parallel and one of them stops while the others continue to operate, SMART requires reduced power operation. A procedure for predicting the performance of SMART MCP for that case was developed and verified with available experimental data. An analysis based on the developed procedure was performed for two cases; the impeller of sloped MCP is fixed or free to rotate in reverse direction. According to the results, $73\%$ flow rate of normal operation enters the reactor core in the case of the locked impeller. In case of the impeller free rotation, the flow rate entering the reactor core is $62.8\%$.

• Transactions of The Korea Fluid Power Systems Society
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• v.8 no.4
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• pp.17-23
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• 2011

Proportional control solenoid is a type of modulating valve that can continuously control the valve position with magnetic force of solenoid. Recent microcontroller based digital servocontroller for proportional valve is being developed toward the smart valve with additional features such as enhanced control algorithm for finer process and intelligent on-board diagnosis for maintenance. In this paper, development of servocontroller network control with CAN bus which is free from problems of security and network traffic jam is presented. Design of network control system includes modes of communication between master and slave, assignment of 29bit message identifier and message objects, transaction of communication sequence, etc. Monitoring function and control experiments for remote valve through CAN network prove the extended function of smart valve control system.

• Journal of the Korean Society of Visualization
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• v.21 no.2
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• pp.63-71
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• 2023

Energy storage and distribution technologies are emerging as important factors as research on renewable energy continues. Analyzing the thermal flow of phase change material inside a latent heat storage device and to predict the phase change time is an important part for improvement of thermal performance. However, most of the current research is based on the trial-and-error experimental investigation to measure the phase change time. Therefore, in this study, a can-type phase change material container was designed, and the numerical method for analyzing the thermal flow of phase change material was established and validated. The error rate of the phase change time between the numerical and experimental results was within 5%, which proves its reliability. As a result, the phase change finishing times were found to be 78 minutes with inlet fluid temperature of 80℃ during charging process, and 126 minutes with inlet fluid temperature of 9℃ during discharging process.

• Structural Engineering and Mechanics
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• v.34 no.4
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• pp.449-474
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• 2010

A smart hollow cylinder consisting of a host functionally graded elastic core layer and two surface homogeneous piezoelectric layers is presented in this paper. The bonding between the layers can be perfect or imperfect, depending on the parameters taken in the general linear spring-layer interface model. The effect of such weak interfaces on free vibration and steady-state response is then investigated. Piezoelectric layers at inner and outer surfaces are polarized axially or radially and act as a sensor and an actuator respectively. For a simply supported condition, the state equations with non-constant coefficients are obtained directly from the formulations of elasticity/piezoelasticity. An approximate laminated model is then introduced for the sake of solving the state equations conveniently. It is further assumed that the hollow cylinder is embedded in an elastic medium and is simultaneously filled with compressible fluid. The interaction between the structure and its surrounding media is taken into account. Numerical examples are finally given with discussions on the effect of some related parameters.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.13 no.9
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• pp.679-687
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• 2003

Shock wave reduction in electrorheological(ER) smart structures is studied. ER insert is a composite structure comprising two elastic outer layers between which is sandwiched layer of ER fluid. When a voltage is applied across the outer layers. the shear modulus and the loss factor of the ER fluid are enabled, and thus the dynamic properties of the composite structure is altered. For the shock wave reduction in a hull mount of a submerged structure, ER inserts are made on the hull mount structure. To investigate the ER insert shape. many types of ER insert pattern are considered. Modal test of ER insert structures is performed to obtain the mode shapes, natural frequencies and the acceleration transmissibility. The acceleration transmissibility is reduced at such a frequency region when an electric field is applied. It is observed that the natural frequencies and mode shapes can be tunable by applying electric field. The ER-inserted hull mount is installed in an integrated system and the overall performance of shock wave reduction is tested. The possibility of shock wave reduction in the hull mount is demonstrated.

• Smart Structures and Systems
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• v.16 no.6
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• pp.1023-1047
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• 2015

In this study, the optimal location of the MR fluid segments in a partially treated laminated composite sandwich plate has been identified to maximize the natural frequencies and the loss factors. The finite element formulation is used to derive the governing differential equations of motion for a partially treated laminated composite sandwich plate embedded with MR fluid and rubber material as the core layer and laminated composite plate as the face layers. An optimization problem is formulated and solved by combining finite element analysis (FEA) and genetic algorithm (GA) to obtain the optimal locations to yield maximum natural frequency and loss factor corresponding to first five modes of flexural vibration of the sandwich plate with various combinations of weighting factors under various boundary conditions. The proposed methodology is validated by comparing the natural frequencies evaluated at optimal locations of MR fluid pockets identified through GA coupled with FEA and the experimental measurements. The converged results suggest that the optimal location of MR fluid pockets is strongly influenced not only by the boundary conditions and modes of vibrations but also by the objectives of maximization of natural frequency and loss factors either individually or combined. The optimal layout could be useful to apply the MR fluid pockets at critical components of large structure to realize more efficient and compact vibration control mechanism with variable damping.

• Journal of Drive and Control
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• v.5 no.3
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• pp.2-8
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• 2008

• Journal of Drive and Control
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• v.15 no.3
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• pp.96-101
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• 2018

• Proceedings of the Korean Nuclear Society Conference
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• 2002.05a
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• pp.120-120
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• 2002

• The KSFM Journal of Fluid Machinery
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• v.17 no.6
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• pp.77-83
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• 2014

The vessel of integral reactor contains its major primary components such as the fuel and core, pumps, steam generators, and a pressurizer, so its size is proportional to the required space for the installation of each component. The steam generators take up the largest volume of internal space of reactor vessel and their volumes is substantial for the overall size of reactor vessel. Reduction of installation space for steam generators can lead to much smaller reactor vessel with resultant decrease of overall cost for the components and related facilities. A printed circuit heat exchanger is one of the compact types of heat exchangers available as an alternative to conventional shell and tube heat exchangers. Its name is derived from the procedure used to manufacture the flat metal plates that form the core of the heat exchanger, which is done by chemical milling. These plates are then stacked and diffusion bonded, converting the plates into a solid metal block containing precisely engineered fluid flow passages. The overall heat transfer area and pressure drops are evaluated for the steam generator based on the concept of the printed circuit heat exchanger in this study. As the printed circuit heat exchanger is known to have much larger heat transfer area density per unit volume, we can expect significantly reduced steam generator compared to former shell and tube type of steam generator. For the introduction of new steam generator, two design requirements are considered: flow area ratio between primary and secondary flow paths, and secondary side parallel channel flow oscillation. The results show that the overall volume of the steam generator can be significantly reduced with printed circuit type of steam generator.