• Journal of Aerospace System Engineering
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• v.11 no.4
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• pp.36-43
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• 2017

Blade design optimization of QTP-UAV prop-rotor was conducted using ModelCenter(R). Performance efficiency of the blade in hover and forward flight were adopted as the multi-objective function. Required power and pitch link force applied to constraint in each flight mode and limited lower than the value of the baseline blade. Design variables of root chord length of the blade, taper ratio, twist slope, twist angle at 0.5R of the blade, anhedral angle, parabolic coefficient of a tip shape and location of airfoil were used to generate the blade planform. CAMRAD-II, the comprehensive analysis program of rotorcraft, was used for performance analysis of prop-rotor blade in design process. Performance of the optimized blade improved 1.6% of figure of merit in hover and 13.6% of propulsive efficiency in forward flight. Pitch link force also reduced approximately 30% less than that of the baseline blade.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.21 no.2
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• pp.7-14
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• 2013

In this paper, the optimal design of composite rotor blade cross-section is performed using a genetic algorithm. Skin thickness, torsion box thickness and skin lay-up angle are adopted as discrete design variables. The position and width of a torsion box are considered as continuous variables. An object function of optimal design is to minimize the mass of a rotor blade, and constraints are failure index, center mass, natural frequency and blade minimum mass per unit length. Finally, design variables such as the thickness and lay-up angles of a skin, and the thickness, position and width of a torsion box are determined by using an in-house program developed for the optimal design of rotor blade cross-section.

• Journal of Aerospace System Engineering
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• v.8 no.1
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• pp.12-17
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• 2014

In this paper, optimal design of composite rotor blade cross-section to consider manufacturability was performed. Skin thickness, torsion box thickness and skin lay-up angle were adopted as discrete design variables and The position and width of a torsion box were considered as continuous variables. An object function of optimal design is to minimize the mass of a rotor blade, and various constraints such as failure index, center mass, shear center, natural frequency and blade minimum mass per unit length were adopted. Finally, design variables such as the thickness and lay-up angles of a skin, and the thickness, position and width of a torsion box were determined by using an in-house program developed for the optimal design of rotor blade cross-section.

• 한국전산유체공학회:학술대회논문집
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• 2008.03b
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• pp.648-651
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• 2008

Numerical calculations are performed to simulate the film cooling effect of turbine blade tip with squealer rim. Because of high temperature of inside rim, squealer rim is damaged easily. Therefore many various cooling systems were used. The calculations are based on 100,000 Reynolds number in linear cascade model. A blade has 2% tip clearance and 8.4% rim height. The axial chord length and turning angle is 237mm, 126$^{\circ}$. Numerical calculations are performed without and with film cooling. In a film cooling in the cavity, hot spots of cavity were cooled effectively. However hot spots of suction side rim still remains. The CFD results show that the circulation flow in cavity of squealer tip affects the temperature rise of squealer rim. To maintain the blade integrity and avoid the excessive hot spot of blade, rearrangement of cooling hole is needed.

• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.6
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• pp.157-163
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• 2018

This study is aimed at controlling the fiber orientation and improve the fiber distribution in fiber-reinforced cement composites using blades that can be placed inside the existing nozzles. To optimize the blade parameters, multi-physics finite element analysis was performed that could account for the flow of the cementitious matrix material, the movement of the entrained fibers, and the interactions with the nozzle. As a result, this study defined the blade distance, length, and position as a function of the fiber length to be used in the field. The blades with a distance from 1.2 to 2.4 times the fiber length and length from 4 to 8 times the fiber length, as well as located at below 14 times the fzfiber length from the nozzle exit maintained the fiber orientation angle less than $5^{\circ}$. In addition, the blade-type nozzle proposed in the study can be attachable and detachable to the conventional casting equipment, and thus it can provide the usability and convenience in practical applications.

• The KSFM Journal of Fluid Machinery
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• v.13 no.3
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• pp.24-29
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• 2010

Axial fans for an air-conditioning unit are designed to equip the system with an expected flow-rate and low noise level by applying the blade design method of multi-sectioning and local camber generation. In this study, the distributions of chord length, stagger angle, and camber angle are globally and locally determined for the given specific speed, which is considered to be relatively high. The mock-up fans are observed to satisfy the aerodynamic performance and the noise level for the system simultaneously and discussed in terms of local flow patterns related to the emitted noise.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.651-654
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• 2001

In the dismantling process of nuclear spent fuels, the spent fuel rod cutting process, followed immediately by the decladding process, performs the cutting the spent fuel rods to a proper length for fast decladding operation. In this paper, we analyzed the chemical compositions, mechanical properties, and physical characteristics for SUS and zircaloy tubes in order to identify the feasibility of cutter-blade type in cutting SUS and zircaloy tubes. It is considered that material, shape and angle, and heat treatment for fabricating the highly durable cutter blade and also it is investigated that the round-shape sustenance of cross-section, amount of debris production, and fire occurrence for measuring the cutting performance on SUS and zircaloy tubes, spent fuel rod cutting device is designed to be operated automatically through the remote control system for use in Hot Cell(radioactive) area and the electro-driven mechanical parts are modularized for easy maintenance. Results from various experiments confirm the efficiency of this device.

• The KSFM Journal of Fluid Machinery
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• v.3 no.2 s.7
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• pp.31-35
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• 2000

In this research, the performance predictions of the submersible mixer were investigated. The variation of the performance characteristics by changing the impeller design parameters were discussed through the flow calculation results by using a commercial program, FLUENT. The performance of the submersible mixers is related to the velocity diffusion profiles downstream of the impeller and also the required input motor power to mix the fluid. In this study, the various design parameters such as the number of blade, the hub and tip diameters, the impeller blade profiles and revolution speed of the blades were taken for the fixed values. The blade sweep direction, the chord length distribution along with the radius of the blade and the inlet blade angle were changed to make different testing models. The flow calculation results show the effect of the changed design parameters on the performance of the submersible mixers and also give some helpful information for designing more efficient submersible mixers.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.1203-1208
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• 2009

In this paper, the flow characteristics of the mixed-flow pump impellers and diffusers were numerically predicted by commercial CFD software and DOE(design of experiments). We also discussed how to improve the performance of the mixed-flow pump by designing the impeller and diffuser in the mixed-flow pump. Geometric design variables were defined by the vane plane development which indicates the blade-angle distributions and length of the impeller and the diffusers. Firstly, the design optimization of the defined impeller geometric variables has been done. After that, the flow characteristics were analyzed in the point of incidence angle at the diffuser leading edge for the optimized impeller. Then design of the defined diffuser shape variables has been performed. The reason for the performance improvement was discussed by examining the flow characteristics through the diffuser.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.9 no.1
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• pp.8-14
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• 2013

Steam turbine blades and discs of nuclear power plants are one of the most highly stressed areas of turbine rotor, and periodic inspection of the blade roots is essential for monitoring integrity and preventing turbine failure. Ultrasonic technique is applied for volumetric inspection of blade root. However, the complexity of blade root geometry imposes challenges to inspection of blades and discs. Recently, phased array ultrasonic inspection technology is being applied to numerous power generation inspection applications including turbine rotor. The phased array ultrasonic technique requires customized inspection wedges which are generally necessary to generate effectively higher incident angle. But the usage of this wedge can cause access limitation for the lower stage blades of turbine because of the wedge front length. Therefore, the shear wave phased array probe which can generate high inspection angle without wedge is essentially necessary. In this study, feasibility study is conducted for the shear wave phased array ultrasonic probe application to blade and disc inspection. As results, the experimental results show that the shear wave phased array probe can detect the flaw and measure its size with reliable accuracy. Therefore if this shear wave phased array probe is applied to field inspection of blade and disc, more reliable inspection is expected for turbine having access limitation.