• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.159.2-159.2
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• 2011

Hyundai Heavy Industries has developed a tidal current energy converter utilizing the accumulated technology as the world largest constructor for ship and offshore structures. The model has two sets of turbines in both ends in order to utilize the bi-directional current flows in flood and ebb tide. The torque produced by turbine in tidal current is directly delivered to generator along the horizontal axis, in which the turbine, gear, generator, gear and turbine are connected successively. The manufactured model for field test has the turbine diameter of 5 meters to produce the maximum power of 500kW at maximum current speed of 5m/s. The technical verification of tidal power converter was performed by means of small scale model test in towing tank as well as field test at the Strait of Uldolmok located in Jindo of Jeollanamdo province. Field test was performed by mounting the tidal current converter on the SEP(Self Elevating Platform) which could lower the 4 vertical legs on the seabed and could elevate platform over the water surface using the hydraulic power for itself. The field test performed for a month shows that power output is similar or larger compared with the expected one in design stage. This paper presents the development of tidal current energy converter and real sea field test by Hyundai Heavy Industries. This project has finished successfully and provided the technical advance toward commercial services for tidal current power generation in the south-west region in Korea.

• Journal of Biomedical Engineering Research
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• v.10 no.2
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• pp.139-150
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• 1989

A new motor-driven blood pump for artificial heart was developed. In this blood pump, a small size, high torque brushless DC motor was used as an energy converter and the motor rolls back and forth on a circular track. This movement of the "rolling-cyliner" causes blood ejection by alternately pushing left or right polyurethane blood sacs. This moving-actuator mechanism could be eliminate two potential problems of other motor-driven artificial hearts such as large size and poor anastomosis for the implantation. Theoretical analyses on the pump efficiency, the temperature rise, and the inflow mechanism were also performed. In a series of mock circulation tests, the theoretical analyses were compared to the measured hemodynamic and mechanical values. The pump system was shown to have sufficient cardiac output (upto 9 L/min), sensitivity to preload, and mechanical stability to be tested as an implantable total artificial heart.ial heart.

• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.2
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• pp.238-245
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• 2018

This paper proposes the applicability of matrix converter topology for the speed control of direct current motors. Matrix convertesr are divided into direct and indirect components. This paper utilizes an indirect matrix converter which is expected to be used widely because of making a variety of output side. The proposed converter has advantages which improves input current shape, has no large energy storage component causing short life. Simulation results are provided to verify effectiveness by comparing and analyzing features of the proposed and conventional topology. The proposed method shows similar performance for speed control, torque control, and load current control compared to a conventional method. Furthermore Harmonics are greatly reduced because the input current is controlled in a manner similar to sinusoidal wave by directly controlling switches at the rectifier stage.

• Journal of Drive and Control
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• v.9 no.4
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• pp.52-57
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• 2012

In this study, in order to understand contents and ranges of design for the EGR Valve test system for improving quality and performance of EGR Valve, engine performance and exhaust gas characteristic of 3L-class diesel engine was analyzed. Experimental operation of engine performance test was performed with 50% engine load and 20% and 100% opening ratio of EGR Valve. From test of performance and exhaust gas characteristic of engine, torque output of engine and temperature and pressure of inlet and outlet of EGR Valve were measured. As a result, for design of EGR Valve test system, input fluid flow of EGR Valve must be set the same amount with exhaust gas flow that was below of engine speed of 2,500 rpm, and temperature of inlet of EGR Valve must be set under about $510^{\circ}C$. And the difference of temperature between inlet and outlet of EGR Valve must be over than about $200^{\circ}C$. Exhaust gas of inlet and outlet of EGR Valve were under 1 bar that was not considerable, and the difference of pressure between inlet and outlet of EGR Valve were under 1 bar that could not effect on mechanical operation of EGR Valve.

• Korean Journal of Computational Design and Engineering
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• v.3 no.1
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• pp.57-67
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• 1998

Genetic programming (GP) is an extension of a genetic algoriths paradigm, deals with tree structures representing computer programs as individuals. In recent, there have been many research activities on applications of GP to various engineering problems including system identification, data mining, function approximation, and so forth. However, standard GP suffers from the lack of the estimation techniques for numerical parameters of the GP tree that is an essential element in treating various engineering applications involving real-valued function approximations. Unlike the other research activities, where nonlinear optimization methods are employed, I adopt the use of a weighted linear associative memory for estimation of these parameters under GP algorithm. This approach can significantly reduce computational cost while the reasonable accurate value for parameters can be obtained. Due to the fact that the GP algorithm is likely to fall into a local minimum, the GP algorithm often fails to generate the tree with the desired accuracy. This motivates to devise a group of additive genetic programming trees (GAGPT) which consists of a primary tree and a set of auxiliary trees. The output of the GAGPT is the summation of outputs of the primary tree and all auxiliary trees. The addition of auxiliary trees makes it possible to improve both the teaming and generalization capability of the GAGPT, since the auxiliary tree evolves toward refining the quality of the GAGPT by optimizing its fitness function. The effectiveness of this approach is verified by applying the GAGPT to the estimation of the principal dimensions of bulk cargo ships and engine torque of the passenger car.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.5
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• pp.1095-1101
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• 2012

This paper presents a design of a BLDC servo motor control system for the auto process of assembly and supply using DSP(Digital Signal Processor) controller and IGBT driver. The assembly and supply auto processing system needs torque, speed, position control of servo motor for variable action. This paper implements those servo control with vector control and space vector PWM(Pulse Width Modulation) technique. As CPU of controller, TMS320F240 DSP was adopted because it has PWM waveform generator, A/D converter, SPI(Serial Peripheral Interface) port and many input/output port etc. This control system consists of 3-level hierarchy structure that main host PC manages three sub DSP system which transfer downward command and are monitoring the states of end servo controllers. Each sub DSP system operates eight BLDC servo controllers which control BLDC motor using DSP and IPM. Between host system and sub DSP communicate with RS-422, between main processor and controller communicate with SPI port.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.5
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• pp.1018-1024
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• 2011

For the driving of the sinusoidal type permanent magnet synchronous motor with a maximum continuous torque, the 1200 delayed three phase sinusoidal current inputs which matched with the absolute rotor position are needed at the stator coil. Therefore, the detection of a absolute rotor position is required inevitably. And the right angle relationship between stator magnetic field and rotor magnetic field has to be preserved at a stator by this commutation action. The detection of a absolute position for the commutation can be made generally by the output signal analysis of the encoder attached at a motor shaft. The purposes of this study are to design signal processing logic circuits which could detect the absolute position of motor with a modern encoder system and generate the three reference wave for making sinusoidal current input at a stator coil.

• Journal of Power Electronics
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• v.15 no.4
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• pp.1047-1053
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• 2015

A time-domain simulation tool to predict the dynamic power output of wind turbines in an offshore wind farm was developed in this study. A wind turbine model consisting of first or second order transfer functions of various wind turbine elements was combined with the Ainslie's eddy viscosity wake model to construct the simulation tool. The wind turbine model also includes an aerodynamic model that is a look up table of power and thrust coefficients with respect to the tip speed ratio and pitch angle of the wind turbine obtained by a commercial multi-body dynamics simulation tool. The wake model includes algorithms of superposition of multiple wakes and propagation based on Taylor's frozen turbulence assumption. Torque and pitch control algorithms were implemented in the simulation tool to perform max-Cp and power regulation control of the wind turbines. The simulation tool calculates wind speeds in the two-dimensional domain of the wind farm at the hub height of the wind turbines and yields power outputs from individual wind turbines. The NREL 5MW reference wind turbine was targeted as a wind turbine to obtain parameters for the simulation. To validate the simulation tool, a Danish offshore wind farm with 80 wind turbines was modelled and used to predict the power from the wind farm. A comparison of the prediction with the measured values available in literature showed that the results from the simulation program were fairly close to the measured results in literature except when the wind turbines are congruent with the wind direction.

• The Transactions of the Korean Institute of Power Electronics
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• v.17 no.5
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• pp.401-408
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• 2012

A simple on-line elimination strategy of the dead time and inverter nonlinearity using the current slope information is presented for a PWM inverter-fed IPMSM (Interior Permanent Magnet Synchronous Motor) drive. In a PWM inverter-fed IPMSM drive, a dead time is inserted to prevent a breakdown of switching device. This distorts the inverter output voltage, resulting in a current distortion and torque ripple. In addition to the dead time, inverter nonlinearity exists in switching devices of the PWM inverter, which is generally dependent on operating conditions such as the temperature, DC link voltage, and current. The proposed scheme is based on the fact that the d-axis current ripple is mainly caused by the dead time and inverter nonlinearity. To eliminate such an influence, the current slope information is determined. The obtained current slope information is processed by the PI controller to estimate the disturbance caused by the dead time and inverter nonlinearity. The overall system is implemented using DSP TMS320F28335 and the validity of the proposed algorithm is verified through the simulation and experiments. Without requiring any additional hardware, the proposed scheme can effectively eliminate the dead time and inverter nonlinearity even in the presence of the parameter uncertainty.

• Journal of the Korean Institute of Gas
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• v.17 no.5
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• pp.8-14
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• 2013

Hydrogen-natural gas blends(HCNG) engine is optimizing technology of performance and emission characteristics with use of hydrogen's fast flame speed and wide flammability limit. As lean-burn limit is extended, the improvement in thermal efficiency and harmful emissions can be achieved. However, the extension of lean-burn limit under a wide open throttle operation point could be realized with the increase in boosting capacity in a lean-burn engine with turbo-charging system. In the present study, the power output characteristics of HCNG engine with turbo-charger change is assessed and feasibility of the increase in boosting capacity is evaluated. The turbo-charger design with high efficiency at higher flow rate rather than higher boosting pressure makes efficient operation possible at relatively rich mixture condition.