• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.29 no.9
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• pp.532-538
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• 2016

In this paper, a underwater acoustic Tonpilz transducer with the piezoelectric single crystal(72PMN-28PT) is developed. The thickness and the number of piezoelectric elements are theoretically designed with the equivalent circuit analysis to have the desired resonance frequency. In order to compare the performances, a piezoelectric ceramic transducer is also manufactured and their electrical impedance, TVR (transmitting voltage response), RVS (receiving voltage response) and beam pattern are compared.

• Membrane Journal
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• v.12 no.1
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• pp.1-7
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• 2002

Currently, the commercialized cation exchange membranes have the excellent performance and stability, however their costs are very expensive and they are not still optimized for the several application areas. A number of membranenologists are focused to solve the problems on the development of novel membrane to be applicable to each membrane field. The present will deal with the introduction of the existing membrane materials and their performances.

• Proceedings of the KIPE Conference
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• 2010.11a
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• pp.261-262
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• 2010

This paper presents the design, development and performance of a power conditioning system (PCS) for application to a Molten Carbonate Fuel Cell (MCFC) for high power generation system. The controller must also supervise the total PCS operation while communicating with the fuel cell system controller. A control method for parallel operation of 250kW PCS was implemented and verified respectively. Experimental performances are compared to minimum target requirements of the PCS for MCFC respectively.

• Journal of the Korean Ceramic Society
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• v.56 no.1
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• pp.1-23
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• 2019

Dielectric materials with inherently high power densities and fast discharge rates are particularly suitable for pulsed power capacitors. The ongoing multifaceted efforts on developing these capacitors are focused on improving their energy density and storage efficiency, as well as ensuring their reliable operation over long periods, including under harsh environments. This review article summarizes the studies that have been conducted to date on the development of high-performance dielectric ceramics for employment in pulsed power capacitors. The energy storage characteristics of various lead-based and lead-free ceramics belonging to linear and nonlinear dielectrics are discussed. Various strategies such as mechanical confinement, self-confinement, core-shell structuring, glass incorporation, chemical modifications, and special sintering routes have been adopted to tailor the electrical properties and energy storage performances of dielectric ceramics. In addition, this review article highlights the challenges and opportunities associated with the development of pulsed power capacitors.

• Molecules and Cells
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• v.45 no.1
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• pp.41-50
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• 2022

The recently developed correlative super-resolution fluorescence microscopy (SRM) and electron microscopy (EM) is a hybrid technique that simultaneously obtains the spatial locations of specific molecules with SRM and the context of the cellular ultrastructure by EM. Although the combination of SRM and EM remains challenging owing to the incompatibility of samples prepared for these techniques, the increasing research attention on these methods has led to drastic improvements in their performances and resulted in wide applications. Here, we review the development of correlative SRM and EM (sCLEM) with a focus on the correlation of EM with different SRM techniques. We discuss the limitations of the integration of these two microscopy techniques and how these challenges can be addressed to improve the quality of correlative images. Finally, we address possible future improvements and advances in the continued development and wide application of sCLEM approaches.

• International Journal of Knowledge Content Development & Technology
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• v.13 no.1
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• pp.101-109
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• 2023

Fifteen years have passed since the enactment of the Industrial Technology Innovation Promotion Act, which promoted industry cooperation activities for universities. Therefore, the study analyzes the relationship between the university's industrial cooperation activities and the college graduates' starting salaries and provides policy suggestions on improving the direction of university-industry cooperation. The study used nine-year panel data from Graduates Occupational Mobility Survey (GOMS) to conduct an empirical analysis and found that starting salaries of college graduates were not significantly higher if the university only participated in basic industry cooperation activities. On the other hand, when the quality of university-industry cooperation activities was higher, such as job search support, the starting salary of college graduates was higher. The findings suggest that university-industry cooperation activities must focus on qualitative performances rather than quantitative approaches.

• Journal of the Korean institute of surface engineering
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• v.56 no.6
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• pp.341-352
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• 2023

This paper reviews the potentials of a rotary chemical vapor deposition (RCVD) process for nanomaterial synthesis and coating on powder-based materials. The rotary reactor offers a significant improvement over traditional CVD methods having horizontal and fixed reaction chambers. The RCVD system yields enhanced productivity and surface coating uniformity of nanoparticles applied in various purposes, such as efficient heat dissipation, surface hardness enhancement, and enhanced energy storage performances. The effectiveness of the RCVD system would open up new possibilities in various applications because uniform coating on powder-based materials with massive productivity is inevitable to develop multi-functional materials with high reliability.

• The Journal of the Acoustical Society of Korea
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• v.39 no.6
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• pp.515-523
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• 2020

This study aims to improve the flow and noise performances of an axial-flow fan for cooling the machine room in a refrigerator by using airfoil-cascade analysis and surface ridge shape. First, the experimental evaluations using a fan performance tester and an anechoic chamber are performed to analyze the flow and noise performances of the existing fan system. Then, the corresponding flow and noise performances are numerically assessed using the Computational Fluid Dynamics (CFD) techniques and the Ffowcs-Williams and Hawkings (FW-H) equation, and the validity of numerical results are confirmed through their comparisons with the experimental results. The analysis for the flow of a cascade of airfoils constructed from the existing fan blades is performed, and the pitch angles for the maximum lift-to-drag ratio are determined. The improved flow performance of the new fan applied with the optimum pitch angles is confirmed. Then, the fan blades with surface ridges on their pressure sides are devised, and the reduction of aerodynamic noise of the ridged fan is numerically confirmed. Finally, the prototype of the final fan model is manufactured, and improvements in the flow and noise performances of the prototype are experimentally confirmed.

• Journal of Institute of Control, Robotics and Systems
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• v.16 no.6
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• pp.566-571
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• 2010

EPS (Electric Power Steering) is important device for improving vehicle's dynamics and static performances. This paper deals with simulator design for C-EPS (Colum type-EPS), development assist and returnability control algorithm. First, C-EPS system model was simply designed because EPS system is complex control system that has many unknown variables. These parameters were simplified through assumptions. Second, C-EPS simulator was designed for development of control algorithm. This simulator has SAS (Steering Angle Sensor), dual torque sensor, dual load cell for measuring rack force, dual linear actuator for generating tire force and Data Acquisition System. Using this simulator, control methods ware tested. Third, control algorithm was designed for torque assist and returnability. Assist torque map and returnability torque map were found by lots of simulation test. These torque maps were tuned for EPS actuator control. The simulation result was compared with non-EPS system result. In this research, the C-EPS simulator was designed for development of control algorithm about torque assistant and returnability. Using this simulator, control algorithm was improved.

• Journal of Magnetics
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• v.17 no.1
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• pp.19-26
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• 2012

This paper deals with the performance analysis and estimation of the electrical parameters of a permanent magnet synchronous generator (PMSG) for hydrokinetic energy conversion applications using vortex induced vibration (VIV). The analytical solutions for the magnetic fields produced by permanent magnets (PMs) and stator winding currents are obtained using a 2D polar coordinate system and a magnetic vector potential. An analytical expression for the 2D permeance is also derived, which takes into account stator skew effects. Based on these magnetic field solutions and the 2D permeance function, electrical circuit parameters such as the backemf constant and the air-gap inductance are obtained analytically. The performances of the PMSG are investigated using the estimated electrical circuit parameters and an equivalent circuit (EC). All analytical results are validated extensively using 2D finite element (FE) analyses. Experimental measurements for parameters such as the back-emf and inductance are also presented to confirm the analyses.