• Advances in Energy Research
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• v.6 no.1
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• pp.35-54
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• 2019

A successful blade design must satisfy some criterions which might be in conflict with maximizing annual energy yield for a specified wind speed distribution. These criterions include maximizing power output, more resistance to fatigue loads, reduction of tip deflection, avoid resonance and minimize weight and cost. These criterions can be satisfied by modifying the geometrical parameters of the blade. This study is dedicated to the aerodynamic assessment of a 20 kW horizontal axis wind turbine operating with two possible airfoils; that is $G{\ddot{o}}ttingen$ 413 and NACA 2415 airfoils (the Gottingen airfoil never been used in wind turbines). For this study parameters such as chord (constant, tapered and elliptic), twist angle (constant and linear) are varied and applied to the two airfoils independently in order to determine the most adequate blade configuration that produce the highest annual energy output. A home built numerical code based on the Blade Element Momentum (BEM) method with both Prandtl tip loss correction and Glauert correction, X-Foil and Weibull distribution is developed in Matlab and validated against available numerical and experimental data. The results of the assessment showed that the NACA 2415 airfoil section with elliptic chord and constant twist angle distributions produced the highest annual energy production.

• Journal of Biosystems Engineering
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• v.18 no.3
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• pp.209-219
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• 1993

A series of soil bin experiment was carried out on sand to investigate if true model theory is applicable to blade-soil system and finally to find mathematical relationship between the dimensionless terms which contain the blade-soil parameters. The following conclusions were derived from the study. 1. It was proved that the draft of the prototype blade can be predicted without distortion by those of model blades with the length scale of 1.2, 2 and 2.4. 2. For the sand, bulk density was found to be a good measure of soil physical properties which are pertinent to predict the draft of the blade-soil system. 3. The mathematical relationship between $D/{\gamma}W$ and d/W, ${\beta}$, and $V^2/Wg$ are as follows ; $$\frac{D}{{\gamma}W^3}=124.98[\frac{d}{W}]^2+7.16[\frac{d}{W}]+0.43 \\ \frac{D}{{\gamma}W^3}=-0.00099{\beta}^2+0.13{\beta}-2.01 \\ \frac{D}{{\gamma}W^3}=0.041[\frac{V^2}{Wg}]^2+0.08[\frac{V^2}{Wg}]+1.3$$

• Transactions of the Korean Society of Machine Tool Engineers
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• v.15 no.6
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• pp.76-81
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• 2006

In this paper, profile error measurement method of a turbine blade using 3D-scanner is developed. The method begins with scanning the upper and lower sides of the blade on which three small balls are attached, and constructs a solid measurement model by registering the two scanned surfaces. Airfoils are derived from the model at each interval by intersecting it with a plane, and arranged with design airfoils. The $2^2$ factorial design search method is engaged in arranging the two airfoils, from which the main blade parameters including the edge radius are computed. The developed measurement technique is applied to practical blade manufacturing and validates its effectiveness.

• Journal of KSNVE
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• v.7 no.5
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• pp.819-826
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• 1997

The finite element analyses of a composite hingeless rotor blade in forward flight have been performed to investigate the influence of blade design parameters on the blade stability. The blade structure is represented by a single cell composite box-beam and its nonclassical effects such as transverse shear and torsion-related warping are considered. The nonlinear periodic differential equations of motion are obtained by moderate deflection beam theory and finite element method based on Hamilton principle. Aerodynamic forces are calculated using the quasi-steady strip theiry with compressibility and reverse flow effects. The coupling effects between the rotor blade and the fuselage are included in a free flight propulsive trim analysis. Damping values are calculated by using the Floquet transition matrix theory from the linearized equations perturbed at equilibrium position of the blade. The aeroelastic results were compared with an alternative analytic approch, and they showed good correlation with each other. Some parametric investigations for the helicopter design variables, such as pretwist and precone angles are carried out to know the aeroelastic behavior of the rotor.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 1993.10a
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• pp.734-743
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• 1993

The performances of three same type of vibrating potato diggers were estimated by observing the potato separation and material flow on the bottom plate. Four-bar mechanism were adopted for three diggers and pairs of eccentric cams on both sides of driving shaft were used as driving link of the diggers. Each machine was tested with different amplitudes , frequencies, and travels speeds. Blade performance were observed in three categories : Impossible forward travel , acceptable operation, and unsatisfactory potato digging , but good material flow. Three parameters were used to set marginal values that enable the machines operate for potato digging, and the parameters were compared to select best one. Three parameters are λ, $\rho$, and K.λ is the ratio of vibrating speed to travel speed, $\rho$ is the ratio of blade acceleration to travel speed, and K is the ratio of blade acceleration to gravitational acceleration. K value of 2 or more is suggested to be used as design and evalu tion criterion of the vibrating digger.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11a
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• pp.275-281
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• 2001

While basic input parameters for the performance and noise of axial fan are flow rate, pressure rise, rotating speed, and fan diameter, the geometric parameters of blade are sweep angle, solidity, and camber angle. The sweep angle does not affect fan performance much, but on fan noise significantly. Solidity and camber angle are very critical design parameters acting on the fan performance directly. The solidity and camber angle are closely related, therefore they have to be carefully determined for the low-noise and high-performance fan. In This paper, different design points are selceted and also geometric parameters are deliberately changed for the comparison of fan noise. As a result, at the same performance, the input rotational speed affects radiated noise more significantly than others. When solidity and camber angle are increased more than those by iDesignFan／sup TM／ program, more noise is experienced. The blade sweep method and blade numbers at same solidity are observed to results in different levels of performance and noise.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.3
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• pp.263-268
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• 2011

We aimed to develop a non-clogging submersible slurry pump with two blades to replace the conventional vortex pump. To do this, we simulated the effect of parameters such as the blade angle $\beta$ and the blade-length angle $\alpha$ on pump efficiency. We used the commercial codes ANSYS CFX and BladeGen. The results showed that the best blade shape was obtained for $\beta$ = $30^{\circ}$ and that the pump efficiency was proportional to $\alpha$ in the simulated range.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.2
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• pp.149-154
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• 2013

This study was performed to develop a high efficiency submersible axial pump for concentration wastewater treatment. To do this, we simulated the effect of some parameters such as the axial twist angle of a blade(${\beta}$), the radial twist angle of a blade(${\alpha}$) and the length of a blade (l) on pump efficiency using commercial code, ANSYS CFX and BladeGen. The results showed that the axial twist angle of a blade(${\beta}$) was the most sensible parameter on the pump efficiency. And the pump efficiency had a maximum at ${\beta}=20^{\circ}$, ${\alpha}=110^{\circ}$ and l=240 mm.

• 유체기계공업학회:학술대회논문집
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• 2004.12a
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• pp.572-577
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• 2004

This paper presents numerical study on the performance improvement of the sirocco fan in a range hood. The performance of sirocco fan means a higher flowrate, a higher static pressure and a lower required motor power in a fixed geometry constraint. Various impeller geometric parameters, such as blade profile, blade diameter, blade thickness profile and blade exit angle, were investigated by numerically and the results were compared with each other to know the effects on the performance. In this approach, the volute geometry were fixed with the original shape. The numerical results show that the blade profile with airfoil shape and small exit blade thickness increases the performance. The blade exit angle shows optimum angle within a varied range. The efficiency of the optimized exit angle was about $10\%$ higher than the base blade exit angle and the static pressure was about $28\%$ higher at the flow coefficient 0.22.

• Proceedings of the Korean Geotechical Society Conference
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• 2003.03a
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• pp.365-368
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• 2003

Despite of the simple equipment and operation, DMT has been widely used to obtain various soil parameters and those parameters have been successfully applied to geotechnical design practice. Among them, the estimation of horizontal coefficient of consolidation is so useful that many researchs recently have been carried out. However, simulation of the penetration of the DMT blade is complex due to the inherent difficulty on analyzing a plane strain deformation of the soil around blade. Therefore, empirical and semi-empirical methods that use the theoretical solution developed fur piezocone with some assumptions have been used to estimate the coefficient of consolidation from Dilatometer dissipation test. In this paper, coefficients of consolidation c$\_$h/ which were obtained using equivalent radius that is same area with the DMT blade and optimization technique are compared with those obtained from Oedometer test and other interpretation methods. It was found that a new method used in this study can give more precise horizontal coefficient of consolidation than other methods do.