• Proceedings of the Korean Society of Marine Engineers Conference
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• 2001.05a
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• pp.28-33
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• 2001

Animation understanding and time-resolved analysis of the wake characteristic of 2-D sharp plane flows were executed by applying the multi-vision PIV to a sharp plane(three angle of attacks : $15^{\circ}, \; 30^{\circ}, \; 45^{\circ}$) submerged within a circulating water channel($Re = 2{\times}10^4$). The macroscopic shedding patterns were discussed in terms of instantaneous velocity, vorticity, velocity profile, kinetic energy, turbulent intensity, frequency analysis. Particularly, the time-averaged distribution of turbulent intensity in each experimental cases revealed separate island-like small regions magnitude of turbulent intensity was always strengthened.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.1442-1446
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• 2004

The heat (mass) transfer characteristics on the blade surface of a first-stage turbine rotor cascade has been investigated by employing the naphthalene sublimation technique. A four-axis profile measurement system is employed for the measurements of the local heat (mass) transfer coefficient on the curved blade surface. The experiments are carried out for two free-stream turbulence intensities of 1.2% and 14.7%. The high free-stream turbulence results in more uniform distributions of heat load on the both pressure and suction surfaces and in an early boundary-layer separation on the suction surface. The heat (mass) transfer enhancement on the suction surface due to the endwall vortices is found to be relatively small under the high free-stream turbulence.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2002.10a
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• pp.99-103
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• 2002

A field test was peformed to estimate the thermal performance of the forced convection electric air heater by the experiment. Air temperature, flow rate and electrical power input were measured with the related measurement sensors, and acquisition methods for the measured data were studied to effectively estimate the thermal performance of the tested air heater. To determine the mean air temperature at the flow cross-section, measuring positions were chosen by considering the flow velocity profile and the equally divided cross-sectional area. From the experimental results, thermal efficiency is obtained as an indication of the tested electric air heater performance.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1999.05a
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• pp.187-192
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• 1999

Noncontact measuring methodology of 3-dimensional profile using CCD camera are very attractive because of it's high measuring speed and its's high sensitivity. Especially when projecting a grid pattern over the object, the captured image have 3 dimensional information of the object. Projection moire extract 3-D information with another grid pattern in front of CCD camera. However phase measuring profilometry(PMP) obtain similar results without additional grid pattern. In this paper, the projection moire are compared with the PMP mathematically, and it is shown that PMP can generate moire image with simple mathematical computations. Experimental works are also carried out showing the same results. It is shown that using a single gird pattern, moire image can be obtained directly without any mathematical operation when some conditions are satisfied.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.31 no.6 s.261
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• pp.659-664
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• 2007

$Moire\'{e}$ interferometry is a useful technique to assess the reliability of electronic package because $Moire\'{e}$ interferometry can measure the whole-field and real-time deformations. The shear strain of a small crack site is important to the reliability assessment of electronic package. The optical limitation of $Moire\'{e}$ interferometry makes ambiguous the shear strain of a small area. An atomic force microscope (AFM) is used to measure the profile of a micro site. High resolution of AFM can apply to the $Moire\'{e}$ technique. AFM $Moire\'{e}$ technique is useful to measure the shear strain of a small area. In this research, the method to accurately measure the deformation of a small area by using AFM $Moire\'{e}$ is proposed. A phase-shifting method is applied to improve the resolution of AFM $Moire\'{e}$.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.13 no.12
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• pp.1184-1195
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• 2001

Analysis of fluid flow in rectangular ducts has been conducted since it has a wide application. The purpose is to provide experimental data for the comparison with computational results. Velocity distributions inside a rectangular duct with $90^{\circ}$ mitered elbow are measured by 5W laser doppler velocity meter for Reynolds numbers of 4,049, 8,104, and 12,186. Flow rates obtained by the integration of measured velocity profile at three cross-sections, which are inlet, middle section after the elbow, and outlet, have errors less than 0.9% among them. Turbulent fluctuation components in two directions are found to have almost similar magnitude each other at a certain location due to the isotropic characteristic of turbulence.

• Journal of Institute of Control, Robotics and Systems
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• v.12 no.1
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• pp.85-92
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• 2006

A new silicon micro flow sensor with multiple temperature sensing elements was proposed and fabricated in considering wide range flow velocity measuring device. Thermal mass flow sensor measures the asymmetry of temperature profile around the heater which is modulated by the fluid flow. A micro mass flow sensor was normally composed of a central heater and a pair of temperature sensing elements around it. A new 2-D wide range micro flow sensor structure with three pairs of temperature sensing elements and a central heater was proposed and numerically simulated by Finite Difference Formulation to confirm the feasibility of the wide flow range sensor structure. To confirm the simulation result, the new flow sensor was fabricated on silicon substrate and the basic flow sensing properties of the sensor were measured.

• Proceedings of the IEEK Conference
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• 2001.06e
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• pp.119-122
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• 2001

This paper deals with new type of active magnetic bearing (AMB) for the linear motors. We adopted optical sensing mechanism for the gap sensing. Using the laser and the PSD (Position Sensitive Device), the absolute rotor position is obtained independent of the profile of the guide rail. With this measurement, the rotor can be controller to follow the straight beam of the laser. Another advantage of optical sensing mechanism might be the elimination of the possible interference between the proximity sensor and the electro-magnet. By adopting the push-full actuating mechanism, the bearing stiffness is increased near the equilibrium position. For the simplicity, distributed control system is constructed. Eight independent PID control algorithm is used with the full order observer. Several simulation md test results are presented.

• 유체기계공업학회:학술대회논문집
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• 2003.12a
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• pp.684-690
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• 2003

A new electrostatic rotary atomizing painting equipment using air turbine was developed. Based on the overall design requirements of painting equipment basic design specifications of the equipment parts such as air turbine and atomizing disk are defined from the present conceptual design model. Air turbine is designed with the section profile of NACA airfoil, and its internal flow field is analyzed by commercial CFD code. Atomizing disk is designed to achieve the ligament type spray of paint with the use of visualization technique. Various experiments and tests are conducted to investigate the spray and the transfer characteristics of newly-designed painting equipment, and the measurement results are compared with the those of conventional painting equipments.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2005.11a
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• pp.111-114
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• 2005

This paper presents a comparison of experimental value by hemispherical grounding simulation system and calculated value by CDEGS program for ground potential rise of structure. When a test current flowed through structure grounding electrodes, ground potential rise was measured and analyzed for types of structure using the hemispherical grounding simulation system in real time, and was computed by means of CDEGS program. The model structures were designed and fabricated with two types on a scale of one-one hundred sixty. When the experimental data were compared with the theoretical values, the similar profile was shown. Therefore, the confidence of measurement was obtained. The distributions of ground surface potential are dependent on the resistivity and absorption percentage in concrete attached to structure.