• Journal of the Korean Society of Propulsion Engineers
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• v.5 no.1
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• pp.76-81
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• 2001

A structural test of the wind turbine rotor blade is to evaluate the uncertainty of design due to selection of material, design concepts, production processes and so on, and their possible impacts on the structural integrity. In the full-scale static strength test, the measuring parameters are strain and displacements vs. loads, weight and the center of gravity. In order to simulate the aerodynamics load, the three-point loading method is applied. There is slight difference between the measured results and the predicted results for the reference fiber volume fraction of 60% . However, the agreement between the measured results and the predicted results with the actual fiber volume fraction of 52.5% is good. Even though a slightly non-linearity from 80% loading to 100% loading exists, a linear static solution is sufficient for the design purpose due to te small amount of non-linearity. Comparison between measured and predicted strain results at the maximum thickness positions of the blade profile for 0.236R(5.56m), 0.493R(11.59m) and 0.574R(13.43m), under 20%, 40%, 60%, 80% and 100% loadings for the upper part of the blade. The predicted values are in good agreement with the measured values.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.11 no.2
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• pp.64-73
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• 1997

Canned type household circulating pump in the country almost depends on the act of imports, however it has disadvantage of low efficiency because an airgap of between rotor and stator is large and when the boiler is not used in a period of summer, a can and a rotor become adhered each other. Accordingly the pump is impossible to drive the initial state, and a lifetime of the pump gets shortening. To overcome these defects a electronic circulating pump by axial air-gap type brushless motor which is completely depart from the general idea for the conventional pump is developed. This paper is verified through experiments that the developed pump has good performance for reduction of size and noise, reo trenchment of cost, and improvement of efficiency in comparison with the conventional pump.

• Journal of the Korean Society for Nondestructive Testing
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• v.30 no.3
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• pp.236-243
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• 2010

Fiber Bragg grating(FBG) sensor arrays can be used to monitor the mechanical behavior of the large composite structures such as wind turbine rotor blades and aircrafts. However, brittle FBG sensors, especially multiplexed FBG sensors are easily damaged when they are installed in the flexible structures. As a protection of brittle FBG sensors, epoxy packaged FBG sensors have been presented in this paper. Finite element analysis and experiments were performed to evaluate the effects of adhesives, packaging materials and the bonding layer thickness on the strain transmission. Two types of epoxy were used for packaging FBG sensors and the sensor probes were attached with various bonding layer thickness. It was observed that thin bonding layer with high elastic modulus ratio of the adhesive to packaging provided good strain transmission. However, the strain transmission was significantly decreased when elastic modulus of the adhesive was much lower than the packaged FBG sensor probe's one.

• Journal of the Korean Society of Visualization
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• v.17 no.1
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• pp.78-84
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• 2019

A gas turbine is the main equipment of a power plant that generates electricity by high-speed rotation of the rotor in a high-temperature environment. In particular, in the case of medium to large-sized gas turbines, the rotor is composed of a plurality of stages, and each component is exposed to different physical environments. Especially, in the case of the tip clearance of the turbine, it is a very important factor in the performance of the design items and the operation of the stable turbine, and a design considering the physical behavior of all major parts should be done. In this study, we will discuss the process of visualizing the physical behavior of turbine operating conditions and the method of designing tip clearance for stable operation by using commercial finite element analysis program for gas turbine assembly model and single product.

• Nuclear Engineering and Technology
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• v.51 no.7
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• pp.1842-1852
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• 2019

The AP1000 reactor coolant pump is a vertical shielded-mixed flow pump, is the most important coolant power supply and energy exchange equipment in nuclear reactor primary circuit system, whose steadystate and transient performance affect the safety of the whole nuclear island. Moreover, safety demonstration of reactor coolant pump is the most important step to judge whether it can be practiced, among which software simulation is the first step of theoretical verification. This paper mainly introduces the fluid-solid coupling simulation method applied to reactor coolant pump, studying the feasibility of simulation results based on workbench fluid-solid coupling technology. The study found that: for the unsteady calculations of the pure liquid media, the average head of the reactor coolant pump with bidirectional fluid-solid coupling decreases to a certain extent. And the coupling result is closer to the real experimental value. The large stress and deformation of rotor under different flow conditions are mainly distributed on impeller and idler, and the stress concentration mainly occurs at the junction of front cover plate and blade outlet. Among the factors that affect the dynamic stress change of rotor, the pressure load takes a dominant position.

• Tribology and Lubricants
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• v.28 no.5
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• pp.197-202
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• 2012

In this study, with the purpose of fundamentally improving the unbalance response vibration of a large PRT motor-generator rotor by design, a performance improvement design analysis is carried-out by retrofitting tilting pad bearings, replacing the plain partial journal bearings that were originally applied for operation at a rated speed of 1,800 rpm. In this process, a goal of the design analysis is to obtain a design solution for maximizing the direct stiffness of the bearings while satisfying the key basic lubrication performance requirements such as the minimum lift-off speed and maximum oil-film temperature. The results show that with a careful design application of tilting pad journal bearings for operation at such a relatively low speed of 1,800 rpm, direct stiffness increment of the bearings by about two times can be effectively achieved. Prevention of pad unloading is also considered in the analysis. Moreover, the designs of elliptical and offset half journal bearings are also analyzed and reviewed.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.03a
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• pp.202-212
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• 2008

A three-dimensional computation was conducted to understand effects of the low Reynolds number on the loss characteristics in a transonic axial compressor, Rotor67. As a gas turbine becomes smaller in size and it is operated at high altitude, the operating condition frequently lies at low Reynolds number. It is generally known that wall boundary layers are thickened and a large separation occurs on the blade surface in axial turbomachinery as the Reynolds number decreases. In this study, it was found that the large viscosity did not affect on the bow shock at the leading edge but significantly did on the location and the intensity of the passage shock. The passage shock moved upstream towards leading edge and its intensity decreased at the low Reynolds number. This change had large effects on the performance as well as the internal flows such as the pressure distribution on the blade surface, tip leakage flow and separation. The total pressure rise and the adiabatic efficiency decreased about 3% individually at the same normalized mass flow rate at the low Reynolds number. In order to analyze this performance drop caused by the low Reynolds number, the total pressure loss was scrutinized through major loss categories such as profile loss, tip leakage loss, endwall loss and shock loss.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.8
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• pp.8-14
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• 2019

Bird-strike is one of the most important design factors for safety in the aviation industry. Bird-strikes have been the cause of significant damage to aircraft and rotorcraft structures and the loss of life. This study used DYTRAN software to simulate the transient response of an Euler-Lagrangian composite helicopter blade that has been impacted by a bird. The Arbitrary Lagrangian Eulerian (ALE) method and a suitable equation of state were applied to model the bird. ALE was applied to the bird-strike analysis due to the large difference between the properties of the blade and bird. The debris of the bird was assumed to be a fluid and applied as Euler elements after the collision. Through the analysis of bird impacts, the leading-edge of the rotor blade (50.8 mm) was used to identify a positive margin of 1.18 based on the TSAI-FILL criteria. The results are assessed to be sufficiently reliable and may be evaluated to replace tests with various analysis conditions. The structural stability of the rotor blade could be assessed by applying various load conditions and different modeling methods in the future.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.21 no.3
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• pp.123-128
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• 2021

For accurate speed and current control in industrial applications, SRM (Switched Reluctance Motor) is very important to synchronize the stator phase excitation and rotor position in the drive due to its nature. In general, position sensors such as encoder and resolver are used to generate rotational force by exciting the stator winding according to the rotor position and to control the motor by using speed and position information. However, for these sensors, 1) the cost of the sensors is quite large in terms of price, so the proportion of the motor system to the total system cost is high. 2) In terms of mechanical, position sensors such as encoders and resolvers are attached to the stator to increase the size and weight. In conclusion, in order to drive the SRM, control based on the rotor position information should be basically performed, and it is important to design the SRM driving system according to the environment in consideration of the application field. Therefore, in this paper, we intend to study the driving and control characteristics of SRM through variable switching duty control by designing a low-cost analog driving device, deviating from the general control system using the conventional encoder and resolver.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.27 no.4
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• pp.250-256
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• 2014

The wind power generation is an eco-friendly clean energy that produces almost zero $CO_2$ emission, and has a good economic feasibility. As for the location, the installation of large turbines and construction of large-scale wind farm is easier on the offshore than on the land. In Korea, it is inevitable to generate offshore wind power through the offshore wind farm, and the radio interference of larger wind power generators and offshore wind power farm to broadcasting, communication and radars is becoming a core issue for constructing the offshore wind farm. In this study, the wind power generation status and rotor blade technology trend were presented, along with the technical trend of radar radio interference reduction relating to construction of the offshore wind farm.