• 한국신재생에너지학회:학술대회논문집
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• 2007.11a
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• pp.387-390
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• 2007

Recently the diameter of the 5MW wind turbine reaches 126m, and the tower height is nearly the same with the wind turbine diameter. The blade will experience periodic inflow oscillation due to blade rotation inside the ground shear flow region, that is, the inflow velocity is maximum at uppermost position and minimum at lowermost position. In this study we compare the aerodynamic data between two inflow conditions, i.e, uniform flow and normal wind profile. From the computed results all of the relative errors for oscillating amplitudes increased due to the ground shear flow effect. Especially My at hub and $F_x$, $M_y$, $M_z$ at LSS increased enormously. It turns out that the aerodynamic analysis including the ground shear flow effect must be considered for fatigue load analysis.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.24 no.4
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• pp.519-525
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• 2000

The effect of nozzle diameter on the local Nusselt number distributions has been investigated for an axisymmetric turbulent jet impinging on the flat plate surface. The flow at the nozzle exit has a fully developed velocity profile. A uniform heat flux boundary condition at the plate surface was created using gold film Intrex. Liquid Crystal was used to measure the plate surface temperature. The experiments were made for the jet Reynolds number (Re) 23,000, the dimensionless nozzle to surface distance (L/d) from 2 to 14, and the nozzle diameter (d) from 1.36 to 3.40 cm. The results show that the Nusselt number at and near the stagnation point increase with an increasing value of the nozzle diameter.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.15 no.4
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• pp.148-154
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• 2016

A study on the micro particle blasting was conducted to find the optimum conditions of the blasted surface of aluminum 6061. The particle type such as $Al_2O_3$ and SiC, nozzle diameter, pressure, standoff distance and injection time were used as blasting conditions. Statistical method of orthogonal arrays(ANOVA) was used to find optimum conditions of maximum depth and maximum diameter of blasted surface. Particle type, nozzle diameter, and pressure were found to be the main factors of maximum blasted depth and diameter. Maximum blasted diameter was affected by increasing pressure and nozzle diameter but saturated maximum diameter. Maximum blasted depth was affected by pressure and nozzle diameter when aluminum 6061 was blasted with $Al_2O_3$ particle. The value of surface roughness was increased as pressure and nozzle diameter increased when aluminum 6061 was blasted with SiC.

• Proceedings of the KSR Conference
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• 2009.05b
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• pp.585-592
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• 2009

The performance of screw compressor depends on lots of design parameters of rotor profile, such as length of seal line, wrap angle, blow hole, suction and discharge port size, number of rotor lobe, etc. The optimum rotor profile makes it possible to increase the compression efficiency with low energy consumption, and to minimize the loss of power. In this research, a new rotor profile design and performance analysis are done by computer simulation. It is expected that the volumetric efficiency is improved because the internal leakage is reduced due to the minimization of blow hole and clearance, and the stiffness of rotors is increased due to the reduction of length to diameter ratio. Also, the specific power consumption will be secured for use ranging from low to high operation speed.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.9 s.186
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• pp.54-60
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• 2006

Fitting process carried out in automobile transmission assembly line is classified into three classes; heat fitting, press fitting, and their combined fitting. Heat fitting is a method that heats gear to a suitable range under the tempering temperature and squeezes it toward the outer diameter of shaft. Its stress depends on the yield strength of gear. Press fitting is a method that generally squeezes gear toward that of shaft at room temperature by press. Another method heats warmly gear and safely squeezes it toward that of shaft. Warm shrink fitting process for automobile transmission part is now gradually increased, but the parts (shaft/gear) assembled by this process produced dimensional changes of gear profile in both radial and circumferential directions. So that it may cause noise and vibration between gears. In order to solve these problems, we need an analysis of warm shrink fitting process, in which design parameters are involved; contact pressure according to fitting interference between outer diameter of shaft and inner diameter of gear, fitting temperature, and profile tolerance of gear. In this study, an closed form equation to predict contact pressure and fitting load was proposed in order to develop optimization technique of warm shrink fitting process and verified its reliability through the experimental results measured in the field and FEM, that is, thermal-structural coupled field analysis. Actual loads measured in the field have a good agreement with the results obtained by theoretical and finite element analysis and also the expanded amounts of the gear profile in both radial and circumferential directions are within the limit tolerances used in the field.

• Transactions of the Korean Society of Mechanical Engineers
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• v.1 no.4
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• pp.182-189
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• 1977

The propagating flame temperature of the Propane-Air premixture by using 30.$\mu$ and 50.$\mu$ diameter platinum sensing wires, that is, Two Wires Correction Method, Through the constant volume burining inside the 150mm diameter, 30mm height combustion chamber under the circumstances of the atomospheric pressure, and the room temperature was determined. Also the temperature distribution across High Temperature Region, i.e. Flame Front, and the temperature profile behind the flame the front have been obtained.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.10a
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• pp.265-268
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• 2003

In the extrusion process, the working material is forced to flow through a die with the desired profile. In general, the width of an extruded section is limited to about an inch less than the diameter of the round billet. But through the lip die, material is spreaded to produce a wider extruded section than the diameter of round billet. In this study, the extrusion process of an aluminum plate using the lip die is investigated. The width of the extruded plate is 450mm that is formed from the round billet with a diameter of 250mm. The flow characteristic through the lip die is considered to produce the wide-extruded plate with a small billet using rigid plastic FE analysis. Based on the result of FE analysis, new designs of lip die are proposed.

• IE interfaces
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• v.15 no.4
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• pp.432-438
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• 2002

When the trailing edge and leading edge of an airfoil contour of high pressure compressor blades are measured, there exists a measurement error due to the size of the probe stylus ball diameter. In the paper an experimental study is provided to determine the optimum diameter of the probe stylus in inspecting the airfoil of the high pressure compressor blade. The measurement and analysis procedure suggested in this paper will be helpful to those who are involved in measuring and inspecting various types of blades.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2002.11a
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• pp.1-6
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• 2002

In the extrusion process, the working material is forced to flow through a die with the desired profile. In general the width of m extruded section is limited to about an inch less than the diameter of the round billet But through the lip die, material is spreaded to produce a wider extruded section than the diameter of round billet. In this study, the extrusion process of an aluminum plate using the lip die is investigated. The width of extruded plate is 450nm that is formed form the round billet with a diameter of 250mm. The flow characteristic through the lip die is considered to produce the wide-extruded plate with a small billet.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2004.10a
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• pp.115-119
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• 2004

In the extrusion process, the working material is forced to flow through a die with the desired profile. In general, the width of an extruded section is limited to about an inch less than the diameter of the round billet. But through the lip die, material is spreaded to produce a wider extruded section than the diameter of round billet. In this study, the extrusion process of an aluminum plate using the lip die is investigated. The width of the extruded plate is 450mm that is formed from the round billet with a diameter of 250mm. The flow characteristic through the lip die is considered to produce the wide-extruded plate with a small billet using rigid plastic FE analysis. Based on the result of FE analysis, an optimized design of the lip die is then proposed.