• Proceedings of the KIEE Conference
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• 2004.11b
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• pp.17-20
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• 2004

This paper presents a modeling and simulation of a grid-connected wind turbine generation system with respect to wind variations and three-phase fault in the system. It describes the modeling of the wind turbine system including the drive train model, induction generator model, and grid-interface model on MATLAB/Simulink. Case studies demonstrate that the pitch angle control is carried out to achieve maximum power extraction for wind speed variations and the duration of a fault on the system influences on the output of the wind turbine generator.

• Journal of the Korean Society for Precision Engineering
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• v.34 no.1
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• pp.41-46
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• 2017

Magnetically levitated (Maglev) vehicles maintain a constant air gap between guideway and car bogie, and thereby achieves non-contact riding. Since the straightness and the flatness of the guideway directly affect the stability of levitation as well as the ride comfort, it is necessary to monitor the status of the guideway and to alert the train operators to any abnormal conditions. In order to develop a signal processing algorithm that extracts guideway irregularities from sensor data, virtual testing using a simulation model would be convenient for analyzing the exact effects of any input as long as the model describes the actual system accurately. Simulation model can also be used as an estimation model. In this paper, we develop a state-space dynamic model of a maglev vehicle system, running on the guideway that contains jumps. This model contains not only the dynamics of the vehicle, but also the descriptions of the power amplifier, the anti-aliasing filter and the sampling delay. A test rig is built for the validation of the model. The test rig consists of a small-scale maglev vehicle, tracks with artificial jumps, and various sensors measuring displacements, accelerations, and coil currents. The experimental data matches well with those from the simulation model, indicating the validity of the model.

• The Transactions of the Korean Institute of Power Electronics
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• v.18 no.3
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• pp.211-216
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• 2013

A wind generator system model includes wind model, rotor dynamics, synchronous generator, power converter, distribution line and infinite bus. This paper investigates the low-Voltage Ride-Through capability of PMSG wind turbine in a variable speed. The drive train of a wind turbine on 2-mass modeling can observe the shaft torsional vibration when the low-voltage occur. To reduce the torsional vibration when the low-voltage occur, this paper designs suppression control algorithm of the torsional vibration and implements simulation. The simulation based on MATLAB/SIMULINK has validated at the transient state of the PMSG and an experiment using 3kW simulator has validated the LVRT control.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.4
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• pp.686-692
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• 2010

This paper analyzes the effect of the STATCOM on the improvement of the Fault Ride Through (FRT) capability of the fixed speed wind turbines(FSWTs). The steady-state models of the wind farm components, such as induction generator, capacitor bank, and the STATCOM, are developed based on the simplified equivalent circuit. Especially, the STATCOM is modeled as a controllable current source and a method that analytically determines the magnitude of the injection current is developed. For the quasi-steady-state(QSS) analysis, the steady-state model of the generator and STATCOM are merged with the dynamic model of drive train. The QSS simulation with the STATCOM shows that the STATCOM can enhance the FRT performance by improving the $W_r-T_e$ characteristics of the FSWTs.

• Proceedings of the KIPE Conference
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• 2011.07a
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• pp.242-244
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• 2011

A wind generator system model includes wind model, rotor dynamics, synchronous generator, power converter, distribution line and infinite bus. This paper investigates the low-Voltage Ride-Through capability of PMSG wind turbine in a variable speed. The drive train of a wind turbine on 2-mass modeling can observe the shaft torsional vibration when the low-voltage occur. To reduce the torsional vibration when the low-voltage occur, this paper designs suppression control algorithm of the torsional vibration and implements simulation. A Matlab/Simulink is used to investigate the response during the transient state.

• Journal of the Korean Society of Industry Convergence
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• v.27 no.4_2
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• pp.925-933
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• 2024

Identification of potential technology convergence opportunities is crucial to drive innovation and growth in modern enterprises. In this study, we proposed a framework to explore technological convergence opportunities based on CPC code sequences from patents by utilizing the BERT model. We relied on the BERT architecture to train a new model using about 1.3 million patents registered at the Korean Intellectual Property Office, and achieved an accuracy of approximately 73% based on HitRate@10 metric. A case study using patents related to wearable technologies was conducted to demonstrate practicability and effectiveness of the proposed framework. The key contributions of this research include: (1) enabling in-depth analysis that takes into account the complex interactions between CPC codes and contextual variability; (2) enabling the exploration of diverse technology convergence scenarios beyond simple sequential patterns. This study is one of the first studies to apply the BERT model for exploring technology convergence opportunities, and is expected to contribute to the establishment of technology innovation and R&D strategies by providing a more accurate and practical tool for enhancing the speed and efficiency of technology opportunity-related decision-making processes.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.10 no.2
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• pp.18-28
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• 2001

Super computers has been utilized to carry out vehicle dynamics in real time. This research propose an implicit integra-tion method for vehicle state variables. Newton chord method is empolyed to solve the equations of motion and con-straints. The equations of motion and constraints are formulated such that the Jacobian matrix for Newton chord method is needed to be computed only once for a dynamic analysis. Numerical experiments showed that the Jacobian matrix generat-ed at the initial time could have been utilized for the Newton chord iterations throughout simulations under various driving conditions. Convergence analysis of Newton chord method with the proposed Jacobian updating method is carried out. The proposed algorithm yielded accurate solutions for a prototype vehicle multibody model in realtime on a 400 MHz PC compatible.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.10
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• pp.73-80
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• 1998

Recently, we have developed a linear brushless DC motor(LBLDCM) with high speed and precise position control performance to apply it to the semiconductor assembly and inspection machinery. It is composed of double side alignment by two armature-stator pairs and each pair is consist of a moving armature with 8 poles by 3 phase coils and a stator with rare earth permanent magnet (Nd-Fe-B) arrays. Through the thrust force analysis on a simplified and whole model of the suggested LBLDCM by an Electromagnetic FEM solver, skew angle of magnet arrays to reduce the thrust force ripple and the winding conditions of the armature is designed. From experimental results, the user's requirements was satisfied and we confirmed distinctly that the repeatable accuracy less than a micron of the linear motion can be obtained at high speed by the developed LBLDCM. This is owing to directly drive the work without the gear train.

• Journal of the Korea Society of Computer and Information
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• v.19 no.12
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• pp.187-196
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• 2014

In this paper, Minimize driving energy for operation within a defined distance yeokgan fixed time-resolved and determine the nature of the train is traveling, and to model mathematically. Urban rail car cruise in general by the PID controller is used instead of automatically tracking a target value while traveling in energy consumption to be minimized by using optimal control model railroad charyangreul was designed under real operating conditions the same. The actual track conditions apply to the minimum value or a separate listing of cars around the track facility without a driving energy of the automatic operation and to reduce the driving energy. Therefore, actual route chosen straight line 8 / gradient segment / curve for the measured data analysis, such as sections within the city-minute drive each section and presented how the trains to save energy, depending on the pattern of the train station in the region.

• International Journal of Internet, Broadcasting and Communication
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• v.15 no.4
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• pp.142-148
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• 2023

In Modern days, Self-driving for modern people is an absolute necessity for transportation and many other reasons. Additionally, after the outbreak of COVID-19, driving by oneself is preferred over other means of transportation for the prevention of infection. However, due to the constant exposure to stressful situations and chronic fatigue one experiences from the work or the traffic to and from it, modern drivers often drive under drowsiness which can lead to serious accidents and fatality. To address this problem, we propose a drowsy driving prevention learning model which detects a driver's state of drowsiness. Furthermore, a method to sound a warning message after drowsiness detection is also presented. This is to use MoveNet to quickly and accurately extract the keypoints of the body of the driver and Dense Neural Network(DNN) to train on real-time driving behaviors, which then immediately warns if an abnormal drowsy posture is detected. With this method, we expect reduction in traffic accident and enhancement in overall traffic safety.