• Proceedings of the KIPE Conference
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• 2001.07a
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• pp.565-568
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• 2001

A novel control scheme compensating for source voltage unbalance and harmonic current for series active power filters is proposed, where the references for voltage unbalance and current harmonic and phase angle is derived from the positive sequence component of the source voltage obtained simply through digital all-pass filters, which makes the whole control algorithm simpler than other methods using p-q theory. In addition, the harmonic component of source current is compensated by harmonic component of load voltage and therefore fundamental component of source current is considered as separated terms for the control issue. The validity of the proposed scheme has been verified by experimental results.

• Journal of Electrical Engineering and Technology
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• v.9 no.2
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• pp.649-654
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• 2014

In this paper, an analytical model for Surrounding Gate (SG) metal-oxide- semiconductor field effect transistors (MOSFETs) considering quantum effects is presented. To achieve this goal, we have used variational approach for solving the Poission and Schrodinger equations. This model is developed to provide an analytical expression for inversion charge distribution function for all regions of device operation. This expression is used to calculate the other important parameters like inversion charge density, threshold voltage, drain current and gate capacitance. The calculated expressions for the above parameters are simple and accurate. This paper also focuses on the gate tunneling issue associated with high dielectric constant. The validity of this model was checked for the devices with different dimensions and bias voltages. The calculated results are compared with the simulation results and they show good agreement.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.2
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• pp.409-415
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• 2017

This paper addresses on an linear matrix inequality (LMI) formulation of the robust waypoint tracking problem of large diameter unmanned underwater vehicles (LDUUVs) in the horizontal plane. The interested design issue can be reformed as the robust asymptotic stabilization of the provided error dynamics with respect to the desired yaw angle, surge speed and attitude. Sufficient conditions for its robust asymptotic stabilizability against the hydrodynamic uncertainties are derived in the format of LMI. An example is provided to testify the validity of the proposed theoretical claims.

• Proceedings of the KIPE Conference
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• 2008.10a
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• pp.64-67
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• 2008

To detect islanding mode when the grid is being tripped is a major safety issue in the Utility Interactive Distributed Generation (UIDG) system. In this paper, analytical design method is suggested for AFD & RPV method under IEEE929-2000 recommended islanding test condition. We have discussed that there is a same point. we injected reactive component of the current by AFD & RPV methods, but the current reference generated is other waveform. Possible if amount of reactive components in this methods are same each method, there is happened same rates frequency variation. To verify the validity of the analytical comparison, this paper presents simulation and experimental results from single phase, 3[kW] inverter for the transformerless UIDG system.

• Special Issue of the Society of Naval Architects of Korea
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• 2015.09a
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• pp.41-45
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• 2015

In this study reviewed the validity of the estimated optimum trim by the numerical analysis. For this purpose, the numerical analysis of the trim optimization for 6500TEU container carrier and capesize bulk carrier were carried out using Star-CCM+, which results were compared with the results of model tests. The reliability of results of the numerical analysis was confirmed via comparing the resistance determined by the numerical analysis and model test. The performance of self-propulsion at each trim conditions were estimated using the calculated resistance by numerical analysis. The BHP at each trim condition were calculated by estimated performance of self-propulsion, which trend of results were confirmed similar trend of result of model test.

• The Transactions of the Korean Institute of Power Electronics
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• v.26 no.5
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• pp.307-314
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• 2021

Even though the LCL filters have superior harmonic attenuation ability to L filters, stability has always been an issue. The system could be unstable because of the resonance phenomenon, especially when digital controller is used. Adding a notch filter to the compensator is one approach to solve the problem. Resonance phenomenon can be inhibited by aligning notch frequency to system resonance frequency. However, resonance frequency variation can be obtained because the actual system has a nonstationary characteristic. Therefore, the system could be unstable, where the system parameters are changed when the conventional notch filter is used. An adaptive digital notch filter that stabilizes the system even system parameters are changed. Simulation and experiment results are provided to verify the validity of the proposed adaptive filter.

• Geomechanics and Engineering
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• v.16 no.6
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• pp.569-575
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• 2018

The stability of shallow cavities with an arbitrary profile is a difficult issue in geotechnical engineering. This paper investigates this problem on the basis of the upper bound theorem of limit analysis and the Hoek-Brown failure criterion. The influence of pore pressure is taken into consideration by regarding it as an external force acting on rock skeleton. An objective function is constructed by equating the internal energy dissipation to the external force work. Then the Lagrange variation approach is used to solve this function. The validity of the proposed method is demonstrated by comparing the analytical solutions with the published research. The relations between shallow and deep cavity are revealed as well. The detaching curve of cavity roof with elliptical profile is obtained. In order to facilitate the application of engineering practice, the numerical results are tabulated, which play an important role in tunnel design and stability analysis of roof. The influential factors on potential collapse are taken into consideration. From the results, the impact of various factors on the extent of detaching is seen intuitively.

• Journal of Engineering Education Research
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• v.22 no.2
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• pp.36-45
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• 2019

Capstone design is a subject taught in a setting where students gather in a team, decide on their own selected topic, and collaborate with one another to perform a project. A fair assessment is very important in a team project-based capstone design course for students. Many instructors agree that harmonizing creative evaluation and outcome assessment is hard in capstone design class. In also, it is not easy to assess students' individual efforts and achievements fairly in accordance with team-based assessment practices. To resolve this issue in this paper, we have surveyed various engineering design education methodologies, and have modelled existing evaluating elements into a modified creative process and outcome assessment framework for team project assessment. In particular, we focused on a method of fairly assigning credits by combining team based and individual-level assessments. Analyzing students' achievement and grade evaluation and verifying the validity of the proposed method was performed.

• Safety and Health at Work
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• v.10 no.2
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• pp.132-140
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• 2019

Background: Increasing workplace health-care perception has become a major issue in the world. Most of the health-related problems are faced because of the lack of health management instruments. The level of health care can be improved through workplace health well-being regulations. The aim of the present study is to formulate a conceptual model of physical checkup. Methods: This study applied conceptual theories and figures and used secondary data from articles and relevant websites for evaluating the validity of the study. Results: Annual health checkup increases health-care awareness perception of states, organizations, employees, and their families and manages the annual health record of employees, organizations, and states. Conclusions: Health care and awareness perception of states, organizations, employees, and families improves with annual health checkup, and annual health checkup also prevents unhealthy acts.

• International conference on construction engineering and project management
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• 2015.10a
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• pp.537-539
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• 2015

considerate operation is a major issue in the equipment-intensive operation. Identifying an optimal equipment combination is important to achieve low-energy operations. An Earthwork operation planning system, which measures the energy consumption of construction operations by taking into account construction equipments' engineering attributes (e.g., weight, capacity, energy consumption rate, etc.) and operation conditions (e.g., road condition, attributes of materials to be moved, geometric information, etc.), is essential to achieve the low-energy consumption. This study develops an automated computerized system which identifies an optimal earthmoving equipment fleet minimizing the energy consumption. The system imports a standard template of earthmoving operation model and compares numerous scenarios using alternative equipment allocation plans. It finds the fleet that minimizes the energy consumption by enumerating all cases using sensitivity analysis. A case study is presented to verify the validity of the system.