• Proceedings of the KSME Conference
• /
• 2002.08a
• /
• pp.447-450
• /
• 2002

The purpose of this 3-D numerical simulation is to calculate and examine a 500 kW Horizontal Axis Wind Turbine (HAWT) power performance and 3-D rotor flow characteristics, which are compared to calculation data from Delft University. The experimental approach, which has been the main method of investigation, appears to be reaching its limits, the cost increasing relate with the size of wind turbines. Hence, the use of Computational Fluid Dynamics (CFD) techniques and Navier-Stokes solvers is considered a very serious contender. We has used the CFD software package CFX-TASCflow as a modeling tool to predict the power performance and 3-D flow characteristics of a wind turbine on the basis of its geometry and operating data. The wind turbine with 40m diameters rotor, it was scaled to compare with the calculation data from delft university. The HAWT, which has eight-rpm variations are investigated respectively. The pitch angle is $+0.5^{\circ}$and wind speed is fixed at 5m/s. The tip speed ratio (TSR) of the HAWT ranging from 2.89 to 9.63.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.16 no.6
• /
• pp.484-489
• /
• 2003

In this paper, a single phase driven piezoelectric motor design was presented for linear motion Two metal/ceramic composite actuators, a piezoelectric ring which was bonded to a metal endcap from one side, were used as the active elements of this motor. The motor was composed of a piezoelectric ceramic, a metal ring which has 4 arms, and a guider. Motors with 30 [mm] and 35 [mm] diameter were studied by finite element analysis and experiments. As results, the maximum speed of motor was obtained at resonance frequency. When the applied voltage of the motor increased, the speed was increased. Also, bidirectional motion of the motor was achieved by combining two motors which have different resonance frequency. But the characteristics of bidirectional motion were not equaled, because of the problem of reproduction on the fabrication and the experiment. If present motor is used at the auto-zoom device of a camera, it will have much advantage. Because the direct linear motion can be achieved with a simple structure of motor and no gearbox of total system.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.12 no.3
• /
• pp.68-75
• /
• 2008

The three-dimensional structure of detonation wave propagating in a circular tube was investigated using a parallel computational code developed previously. A series of parametric study for a circular tube of a fixed diameter gave the formation mechanism of the detonation cell structures depending on pre-exponential factor, k. The unsteady results in three-dimension showed the mechanisms of two, three and four cell mode of detonation wave front structures. The detonation cell number was increased but cell width and length were decreased with increased pre-exponential factor k. In the all multi-cell mode, the detonation wave structure and smoked-foil records on the wall are made by the moving of transverse waves. The detonation wave front structures have the regular polygon and windmill shapes periodically.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.5 no.4
• /
• pp.13-20
• /
• 2006

The inherent problem of a Darrieus wind turbine is its inability to self-start. Usually, a motor is used to provide angular acceleration until lift forces are produced in the airfoil blades or up until the turbine can already sustain its speed on its own. This paper describes a method of improving the self-starting of an H-type Darrieus vertical axis wind turbine (VAWT) by incorporating a helical Savonius turbine thus utilizing a drag-lift combination. The effect of each turbine in the combination relative to each other is investigated by testing a prototype windmill consisting of three NACA 0015 airfoil blades combined with a Savonius rotor with a helix angle of 180 degrees and whose swept area equals 30% of the entire turbine.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.37 no.4
• /
• pp.545-550
• /
• 2010

Freeman-Sheldon Syndrome (FSS, also known as "Whistling Face Syndrome") is a rare genetic condition which characteristically includes a small "whistling" mouth, a flat mask-like face, club feet, joint contractures usually involving the fingers and hands, and under-development of the cartilage of the nose. Intelligence is usually normal. Most of the features of this syndrome are due to muscle weakness. The patient, 11 years old boy was consulted from pediatrics to pediatric dentistry due to dental management. After clinical & radiographic examinations, severe multiple problems were found. Dental problems were microsomia(whistling mouth) & micrognathia, perioral muscle contracture, restricted mouth opening, poor oral hygiene & care, generalized dental caries, high palatal vault, severe malocclusion & crowding. And Orthopedic problems, ophthalmic & respiratory, anesthetic problems were found. Then He also had psychiatric problem, hospital(dental) phobia due to previous medical history(frequent hospitalization). And he had genital problem, cryptochidism, too. Due to these intricate problems, he suffered with feeding, swallowing difficulties and showed growth retardation. For enhancing patient's oral health, pediatric dentist, orthodontist, oral surgeon, pediatrician, psychiatrist, orthopedist, they all agree with early, cautious intervention and treatment. So, he has been treated by multidisciplinary care, now he is recovering general health maintenance.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.21 no.5
• /
• pp.53-59
• /
• 2007

Now, the study is activity that the energy market depending on a fossil fuel tend to change different way. In middle of the study compositive use of renewable energy(fuel cell and wind power, solar cell, etc.) is dispersion power system which concern is increasing. But in the case of generation of electric wind power system is changeable to be turbulence and wind and win speed are changeable in several seconds, so making the best of wind energy the MPPT that role in this case is important. In this paper suggest a MPPT which is making a use of information of wind speed and turning speed, windmill, electric power but it is simpler than former way. We could verify that a proposed controller working at the highest point of electric power when wind speed is regular speed and changable speed through the simulation.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.18 no.2
• /
• pp.142-149
• /
• 2004

This paper presents a neural network controller of a grid-connected wind energy conversion system for extracting maximum power from wind and a power controller to transfer the maximum power extracted into a utility grid. It discusses the modeling and simulation of the wind energy conversion system with the controllers, which consists of an induction generator, a transformer, a link of a rectifier, and an inverter. The paper describes tile drive train model, induction generator model and grid-interface model for dynamics analysis. Maximum power extraction is achieved by controlling the pitch angle of the rotor blades by a neural network controller. Pitch control method is mechanically complicated, but the control performance is better than that of the stall regulation. The simulation results performed on MATLAB show the variation of the generator torque, the generator rotor speed, the pitch angle, and real/reactive power injected into the grid, etc. Based on the simulation results, the effectiveness of the proposed controllers is verified.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.19 no.1
• /
• pp.59-65
• /
• 2013

In recent years, the crisis of energy is growing seriously and also the contamination of ecology has been reverberated as international problem. The social concerns on energy crisis have been growing for the last several years and also the interests in new and renewable energy have been increased. Therefore, in order to solving these problems, as solution of one, this paper is investigated using the aeration system at the fish farm, etc from nature energy such as wind power. This study suggests the fundamental data of designing for these similar apparatus and examines the parameters of wind velocity and wind receiving area. Especially, the water outlet position was mainly investigated with optimum outlet angle of wind pump.

• Korean Journal Plant Pathology
• /
• v.3 no.4
• /
• pp.291-298
• /
• 1987

Samples showing mosaic symptom of cowpea (Vigna sesquipedalis) with vein banding, chlorotic spot, vein yellow were collected from Chinju areas in Korea, Two viruses were distinguishable by stability in sap, host range, and relations with cells and tissues were examined under an electron microscope, Blackeye cowpea mosaic(BICMV) was sap-transmissible to 7 plant species in 2 families, Of the plants, only leguminous species were systemically infected. This virus was inactivated by heating at $50-65^{\circ}C$ for 10 min, by diluting at $10^{-4}-10^{-5}$, and aging at room temperature for 1-6 days. Preparations examined under the electron microscope by direct negative staining method(DN -method) always showed particles of flexuous filament bout 750nm in length and cytopasmic inclusions. Cytoplasmic inclusions and virus particles were also confirmed to present in the cytoplasm of a mesophyll cell by ultrathin sections of BICMV infected cowpea leaves. Cucumber mosaic virus (CMV) was transmitted by sap- inoculation on inoculated leaves of Chenopodium amaranticolor, C. quinoa producing local lesions, but non-inoculated upper leaves of Nicotiana glutinosa, Cucurbita pepo and Vigna sesquipedalis producting systemic mosaic symptoms. Electron microscopic examination of virus preparation by direct negative staining showed spherical particles of about 30nm in diameter. In ultrathin sections of CMV infected tissues, virus particles of crystalline array were found in the vacuole and a large number of virus particles were found in the cytoplasm and the plasmodesmata of mesophyll cells.