• Transactions of the Korean Society of Mechanical Engineers B
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• v.30 no.10 s.253
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• pp.942-949
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• 2006

A lumped model is proposed to predict liquid ejection characteristics of a thermally driven inkjet print head. The model is based on a two-dimensional heat conduction equation, an empirical pressure-temperature equation and a nonlinear hydraulic flow-pressure equation. It has been simulated through the construction of an equivalent R-C circuit, and subsequently analyzed using SIMULINK and a circuit simulation tool, PLECS. Using the model, heating and cooling characteristics of the head are predicted to be in agreement with the IR temperature measurements. The effects of the head geometry on the drop ejection are also analyzed using the nonlinear hydraulic model. The present model can be used as a design tool for a better design of thermal inkjet print heads.

• Journal of the Korean Society for Precision Engineering
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• v.24 no.11
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• pp.101-107
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• 2007

Jettability analysis using one-dimensional(1D) lumped parameter model has been investigated to design the industrial inkjet head with proper drop velocity and drop volume. By simplifying the inkjet head system into an equivalent electrical circuit, lumped model has been developed. Performance of the lumped model is verified by the comparison between measured results of droplet velocity and ejection volume and predicted value. Also, the jetting performance of an inkjet head is characterized by varying the design parameter and driving condition. As a result, simulation results shows good agreement with the experimentally measured value. The developed lumped model enables to easily understand the effect of dimension change and predict the jetting performance.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.43 no.12 s.354
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• pp.23-32
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• 2006

Fast and accurate power bus design (FAPUD) method for multi-layers high-speed digital boards is devised for the power supply network design tool for accurate and precise high speed board. FAPUD is constructed, based on two main algorithms of the PBEC (Path Based Equivalent Circuit) model and the network synthesis method. The PBEC model exploits simple arithmetic expressions of the lumped 1-D circuit model from the electrical parameters of a 2-D power distribution network. The circuit level design based on PBEC is carried with the proposed regional approach. The circuit level design directly calculates and determines the size of on-chip decoupling capacitors, the size and the location of off-chip decoupling capacitors, and the effective inductances of the package power bus. As a design output, a lumped circuit model and a pre-layout of the power bus including a whole decoupling capacitors are obtained after processing FAPUD. In the tuning procedure, the board re-optimization considering simultaneous switching noise (SSN) added by I/O switching can be carried out because the I/O switching effect on a power supply noise can be estimated over the operation frequency range with the lumped circuit model. Furthermore, if a design changes or needs to be tuned, FAPUD can modify design by replacing decoupling capacitors without consuming other design resources. Finally, FAPUD is accurate compared with conventional PEEC-based design tools, and its design time is 10 times faster than that of conventional PEEC-based design tools.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.8
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• pp.697-703
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• 2017

A teflon ionization modeling has been conducted to predict the performance of a PPT(Pulsed Plasma Thruster). One dimensional unsteady circuit model and Teflon ablation model were implemented. The Saha equation was adapted to predict the ionization of Carbon and Fluorine gas. The lumped circuit model including a resistance and a inductance model of a plasma was adapted to predict the magnitude of a discharge current. Numerical simulation results had good agreements with pervious research. The degree of current change according to PPT operating voltage was examined.

• Progress in Superconductivity and Cryogenics
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• v.21 no.1
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• pp.31-35
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• 2019

The lumped-parameter circuit model for a no- insulation (NI) high temperature superconductor (HTS) magnet has been well understood after many experimental and analytic studies over a decade. It successfully explains the non-linear charging behaviors of NI magnets. Yet, recently, multiple groups reported that the post-quench electromechanical behaviors of an NI HTS magnet may not be well explained by the lumped circuit model. The characteristic resistance of an NI magnet is one of the key parameters to characterize the so-called "NI behaviors" of an NI magnet and recently a few groups reported a potential that the characteristic resistance of an NI magnet may substantially vary during a quench. This paper deals with this issue, the increment of contact resistance of the no-insulation (NI) REBCO magnet during a quench and its impact on the post-quench behaviors. A 7 T 78 mm NI REBCO magnet that was previously built by the MIT Francis Bitter Magnet Laboratory was chosen for our simulation to investigate the increment of contact resistance to better duplicate the post-quench coil voltages in the simulation. The simulation results showed that using the contact resistance value measured in the liquid nitrogen test, the magnitude of the current through the coil must be much greater than the critical current. This indicates that the value of the contact resistance should increase sharply after the quench occurs, depending on the lumped circuit model.

• International Journal of Precision Engineering and Manufacturing
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• v.9 no.2
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• pp.50-53
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• 2008

A design approach using a one-dimensional (1D) lumped model was studied and applied to an industrial inkjet printing head design for micro patterning on printed circuit boards. For an accurate analysis, a three-dimensional piezoelectric-driven actuator model was analyzed and its jetting characteristics were applied to 1Danalysis model. The performance of the 1D lumped model was verified by comparing measured and simulated results. The developed 1D model helped to optimize the design and configuration of the inkjet head and could be implemented in the design of multi-nozzle inkjet printing heads to improve the jetting frequency and minimize crosstalk.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.31 no.2 s.257
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• pp.141-150
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• 2007

This paper presents a lumped model to predict crosstalk characteristics of thermally driven inkjet print heads. Using the lumped R-C model, heating characteristics of the head are predicted to be in agreement with IR temperature measurements. The inter-channel crosstalk is simulated using the lumped R-L network. The values of viscous flow resistance, R and flow inertance, L of connecting channels are adjusted to accord with the 3-D numerical simulation results of three adjacent jets. The crosstalk behaviors of a back shooter head as well as a top shooter head have been investigated. Predictions of the proposed lumped model on the meniscus oscillations are consistent with numerical simulation results. Comparison of the lumped model with experimental results identifies that abnormal two-drop ejection phenomena are related to the increased meniscus oscillations because of the more severe crosstalk effects at higher printing speeds. The degree of crosstalk has been quantified using cross-correlations between neighboring channels and a critical channel dimension for acceptable crosstalk has been proposed and validated with the numerical simulations. Our model can be used as a design tool for a better design of thermal inkjet print heads to minimize crosstalk effects.

• Progress in Superconductivity and Cryogenics
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• v.25 no.3
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• pp.38-42
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• 2023

The evaluation of no-insulation (NI) high-temperature superconducting (HTS) typically uses the lumped equivalent circuit (LEC) model. Constant parameters in the NI HTS LEC model accurately predict voltage and central magnetic field at currents below the critical current. However, it is difficult to find constant circuit parameters that simultaneously satisfy the measured voltage and magnetic field under overcurrent conditions. Recent research highlights changes in contact resistance during transient conditions, which may impact power loss estimation in NI HTS coils. Therefore, we confirm the influence of contact resistance changes on loss calculation in the transient state for NI HTS coil. To achieve this, we introduce a measurement data analysis method based on the LEC model and compare it with the LEC model using constant circuit parameters.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07a
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• pp.115-118
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• 2002

This paper presents the design method and performance characteristics of a chip-type quadrature hybrid using LTCC-MLC technology. The design method for a chip-type quadrature hybrid is based on lumped element equivalent circuit of quarter-wave transformer. The chip-type quadrature hybrid was miniaturized to a greater extent using multilayer structure and lumped element. The proposed design method can also reduce the undesirable parasitic effects of the chip-type quadrature hybrid. The proposed chip-type quadrature hybrid was designed and fabricated using the proposed design method and the equivalent circuit model of a quarter-wave transformer. Fabrication and measurement of designed chip-type quadrature hybrid show much smaller size than a conventional distributed quadrature hybrid and a good agreement with simulated results.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.101-102
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• 2011

The attraction force is an important parameter for permanent-magnet(PM) linear machines. This paper aims to analysis lumped magnetic circuit model of a magnetic levitation system. It accounts for the fringing effect and leakage flux which may greatly affect the accuracy of the analytical model for the optimal lumped magnetic circuit model. consequentially it will be able to apply to prospective permanent-magnet(PM) linear machines for accurate analysis.