• Proceedings of the KIPE Conference
• /
• 2005.07a
• /
• pp.520-522
• /
• 2005

Islanding phenomenon is undesirable because it lead to a safety hazard to utility service personnel and may cause damage to power generation and power supply facilities as a result of unsynchronized reclosure. In order to prevent this phenomenon, various anti-islanding methods have been studied. Even though the slip mode frequency shift (SMS) method has been regarded as a highly effective anti-islanding method, the analytical design method of that was not cleared. This paper proposes a modeling of the SMS method using non-detection zone (NDZ) and evaluation of the method according to the test conditions of IEEE Std. 929-2000. The SMS method is derived analytically through the modeling and verified visually by simulation and experiment.

• Proceedings of the KIEE Conference
• /
• 2005.07b
• /
• pp.1699-1701
• /
• 2005

Islanding phenomenon is undesirable because it lead to a safety hazard to utility service personnel and may cause damage to power generation and rower supply facilities as a result of unsynchronized reclosure. In order to prevent this phenomenon, various anti-islanding methods have been studied. Even though the slip mode frequency shift(SMS) method has been regarded as a highly effective anti-islanding method, the analytical design method of that was not cleared. This paper proposes a modeling of the SMS method using non-detection tone(NDZ) and evaluation of the method according to the test conditions of IEEE Std. 929-2000. The SMS method is derived analytically through modeling and verified visually by simulation and experiment.

• International conference on construction engineering and project management
• /
• 2022.06a
• /
• pp.393-400
• /
• 2022

Agent-based modeling (ABM), as a relatively new simulation technique, has recently gained in popularity in the civil engineering domain due to its uniquely advantageous features. Among many civil engineering applications, ABM has been applied to facility operation and management, such as energy consumption management, as well as the enhancement of maintenance and repair processes. The former studies used ABM to manage energy consumption through simulating human energy-related behaviors and their interactions with facilities, as well as electrical, heating, and cooling systems and appliances, while the latter used ABM to enhance maintenance process through facilitating coordination, negotiation, and decision making between facility managers, service providers, and repair workers. The present study aims to provide a short qualitative review on the most recent applications of ABM in the above-mentioned areas. Based on the review and follow-up analysis, the study identifies the advantages, disadvantages, and limitations of ABM applications to facility operation and management, and offers several potential future research topics in the hope of filling the existing literature gaps.

• Nuclear Engineering and Technology
• /
• v.56 no.8
• /
• pp.3242-3254
• /
• 2024

With the increasing usage of nuclear energy, how to properly dispose nuclear waste becomes a critical issue. In this study, a multiscale modeling approach combining the experimental findings is presented to address the illitization process, its impact on transport properties, and system behavior of bentonite buffer in engineered barrier systems (EBS). Through the pore-scale modeling, reactive transport properties such as illite generation rate and effective diffusion coefficient of potassium ion as a function of porosity and temperature are quantified by employing the findings of hydrothermal reaction experiments of Bentonil-WRK. The capability of pore-scale modeling has been developed based on the Darcy-Brinkmann-Stokes equation, involving the processes of smectite illitization and clay swelling. Obtained reactive transport properties are utilized as input parameters for the macroscale modeling to predict the long-term behavior of bentonite buffer in EBS. As such, this study involves the whole workflow of quantifying the reaction parameters of smectite illitization through the hydrothermal reaction experiments, and numerically modeling the reactive transport process of smectite illitization in bentonite buffer of EBS from pore-scale to macroscale. The presented multiscale modeling findings are expected to provide reliable solution for safe nuclear waste disposal with EBS.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2008.11a
• /
• pp.357-358
• /
• 2008

• Journal of Mechanical Science and Technology
• /
• v.20 no.2
• /
• pp.278-285
• /
• 2006

The present study has been conducted to simulate dynamics of a gas engine-driven heat pump (GHP) for design of control algorithm. The dynamics modeling of a GHP was based on conservation laws of mass and energy. For automatic control of refrigerant pressures, actuators such as engine speed, outdoor fans, coolant three-way valves and liquid injection valves were PI or P controlled. The simulation results were found to be realistic enough to apply for control algorithm design. The model can be applied to build a virtual real-time GHP system so that it interfaces with a real controller in purpose of prototyping control algorithm.

• Journal of the Korean Electrochemical Society
• /
• v.22 no.1
• /
• pp.43-52
• /
• 2019

As the application area of lithium secondary batteries becomes wider, performance characterization becomes difficult as well as diverse. To address this issue, battery manufacturers have to evaluate many batteries for a longer period, recruit many researchers and continuously introduce expensive equipment. Simulation techniques based on battery modeling are being introduced to solve such difficulties. Various lithium secondary battery modeling techniques have been reported so far and optimal techniques have been selected and utilized according to their purpose. In this review, the electrochemical modeling based on the Newman model is described in detail. Particularly, we will explain the physical meaning of each equation included in the model; the Butler-Volmer equation, which represents the rate of electrode reaction, the material and charge balance equations for each phase (solid and liquid), and the energy balance. Moreover, simple modeling processes and results based on COMSOL Multiphysics 5.3a will be provided and discussed.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.25 no.3
• /
• pp.176-181
• /
• 2012

Due to the high etch rate and low fabrication cost, the wet etching of silicon using KOH etchant is widely used in MEMS fabrication area. However, anisotropic etch characteristic obstruct intuitional mask design and compensation structures are required for mask design level. Therefore, the accurate modeling for various types of silicon surface is essential for fabrication of three-dimensional MEMS structure. In this paper, we modeled KOH etch profile for MEMS based energy harvester using fuzzy logic. Modeling results are compared with experimental results and it is applied to design of compensation structure for MEMS based energy harvester. Through Fuzzy inference approaches, developed model showed good agreement with the experimental results with limited etch rate information.

• Journal of the Korean Solar Energy Society
• /
• v.34 no.1
• /
• pp.91-97
• /
• 2014

This paper proposes a modeling of fuel cell which replaces dc source during simulation. Fuel cells are electrochemical devices that convert chemical energy in fuels into electrical energy. This system has high efficiency and heat, no environmental chemical pollutions and noise. Proton exchange membrane fuel cells (PEMFC) are commonly used as a residential generator. These fuel cells have different electrical characteristics such as a low voltage and high current compared with solar cells. And there are different behaviors in the V-I curve in the temperature and pressure. Therefore, the modeling of fuel cell should consider wide voltage range and slow current response and the resulting electrical model is applied to boost converter with fuel cell as an input source.

• Journal of Electrical Engineering and Technology
• /
• v.13 no.5
• /
• pp.1935-1944
• /
• 2018

With the increase of the production of energy from renewable, it becomes important to look at techniques to store this energy. Therefore, a single winding bearingless flywheel motor (SWBFM) specially for flywheel energy storage system is introduced. For the control system of SWBFM, coupling between the torque and the suspension subsystems exists inevitably. It is necessary to build a reasonable radial force mathematical model to precisely control SWBFM. However, SWBFM has twelve independently controlled windings which leads to high-order matrix transformation and complex differential calculation in the process of mathematical modeling based on virtual displacement method. In this frame, a Maxwell tensor modeling method which is no need the detailed derivation and complex theoretical computation is present. Moreover, it possesses advantages of universality, accuracy, and directness. The fringing magnetic path is improved from straight and circular lines to elliptical line and the rationality of elliptical line is verified by virtual displacement theory according to electromagnetic torque characteristics. A correction function is taken to increase the model accuracy based on finite element analysis. Simulation and experimental results show that the control system of SWBFM with radial force mathematical model based on Maxwell tensor method is feasible and has high precision.