• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 1997.10a
• /
• pp.480-483
• /
• 1997

In this paper, we have proposed an automatic inspection system for cracks on the surface of a structure. The proposed system consists of the imaging system and the veh~cle system. The imaging system. a set of optical sensor, lens, illuminator, storage and their configuration, images the scene and store it on the hard disk. We adopted a linescan camera of 5000 pixel density to achieve high resolution without loss of simplicity. The vehicle system that moves the optical system IS ~mplemented by an AGV. The AGV moves forward at constant velocity and avoid obstacles to acquire a stable image. We have cmplemented an experimental system and have acquired images of the wall of hallway. The image is of 0.1-mmipixel resolution and the scanning time IS about 1 mlsec. The allow able scan.

• Journal of Advanced Marine Engineering and Technology
• /
• v.28 no.2
• /
• pp.263-268
• /
• 2004

The characteristics of Diesel spray droplets, such as the velocity and the diameter were simultaneously measured by using an improved Interferometric Laser Imaging for Droplet Sizing method. The experiments were carried out using an accumulator-type unit injector system and a constant-volume vessel. Two dimensional cross-section photographs of sprays were also taken using a double-pulsed Nd- YAG laser sheet and a linear array CCD camera. As a result, interesting relations between the droplets diameter and the velocity were found.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 1994.10a
• /
• pp.499-503
• /
• 1994

The feedback control systems of welding process using visual information can improve weld qualities. However, it is very difficult to get the visual information of weld pool since welding are is much stronger than light from weld pool. To explore the possibility of extending the capability of automatic welding machines a study of a closed loop controlled welding system consisted of a GTA welding machine, a vision system, a stepping motor system and a digital computer was undertaken. Particularly, in this system, a CCD camera with 850nm long pass filter was focused on the weld pool to give a weld pool image. Subsequently, image analysis technique has been developed to measure a weld pool width. Using this weld pool width measurement, a colsed loop control system adjusted welding speed to maintain constant weld pool width.

• Journal of the Korea Society of Computer and Information
• /
• v.12 no.2 s.46
• /
• pp.103-109
• /
• 2007

In this paper, we detect shot boundaries using $X^2$-histogram comparison method which have enough spatial information that is more robust to the camera or object motion and produce more precise results. Also, we present normalization method to change Log-Formula and constant that is used for contrast enhancement of image in image processing and apply in difference value. And, present shot boundary detection algorithm to detect shot boundary based on general shot and abrupt shot's characteristic.

• Journal of the Korean Society of Visualization
• /
• v.9 no.2
• /
• pp.48-53
• /
• 2011

The shape of nozzle cross-section plays an important role in stabilizing electrospray jet. The angle of contact line is governed based on the famous Young-Laplace equation. Compared to a round nozzle that has a constant curvature along the orifice, the square nozzle has four square corner edges and four straight edges that hold the meniscus in a different manner and is of interest in this study. By utilizing both square and round capillary nozzle, we examine the effect of nozzle shape in electrohydrodynamic jetting. The ejections were recorded with a high speed camera and analyzed to examine the jetting repeatability based on dynamic movement of meniscus. The result suggests that if the corner edges are not sharp, then its effect on repeatability is also limited.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.3 no.6
• /
• pp.274-284
• /
• 1995

The effect of turbulence and ignition energy on flame kernel growth in mathanol-air mixtures has been studied in a constant volume vessel. Experiments were made under different turbulent intensity conditions, ignition energy and over a range of equivalence ratio. Characteristics of turbulent flow were grasped by measurments of gas pressure and visualization of flame propagation. Flow velocity was measured by use of hot wire anemometer. A comparison of the effect of turbulence on ignition probability and flame kernel volume variation ratio is also presented.

• Journal of ILASS-Korea
• /
• v.25 no.1
• /
• pp.15-20
• /
• 2020

This study aims to investigate injection rate and microscopic spray characteristics of diesel fuel containing fine air bubble (FBD). fine bubble was generated by cavitation theory using bubble generator. Fuel spray was injected into constant volume chamber and visualized by high speed camera. The injection rate data was acquired with bosch tube method. Injection rate of finebubble diesel was very similar with that of diesel. It showed slightly faster injection start by 5 ㎲ attributed to the low viscosity characteristics. In microscopic spray visualization, fine bubble diesel spray showed unsymmetric spray shape compared with diesel spray. It also showed very vigorous spray atomization performance during initial spray development. Improved atomization was also attributed to the low viscosity and surface tension of finebubble diesel fuel.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.11 no.2
• /
• pp.47-53
• /
• 2007

Convective heat transfer coefficient was measured around a circular secondary jet ejected into the supersonic flow field. The wall temperature measurement around a injection nozzle was conducted using infra-red camera. The constant heat flux is applied to the wall around a secondary nozzle. According to jet to freestream momentum ratio, the injection flow penetrates into the supersonic flow field. The measured temperature is used to calculate the convective heat transfer coefficient.

• Journal of Industrial Technology
• /
• v.31 no.A
• /
• pp.95-101
• /
• 2011

According to recent technological developments in high-power LEDs, the stage lighting is one of most important areas to apply power LED system. Moving light for color rendering of stage uses the RGBW(red, green, blue, white) color mixing method. LED moving light system needs to have a wide range of dimming control as enough to operate at very low power. Also LED dimming system should not be induced color-shift and flicker in camera. This paper is experimentally verified the LED Moving Light driving circuit of 200Watt level designed to satisfy the above characteristics which applied the DC current-controlled and PWM mixed dimming method.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.60 no.3
• /
• pp.600-605
• /
• 2011

This paper shows field test and evaluation results for a wireless vehicle detector with anisotropic magneto-resistive (AMR) sensors. The detector consists of two AMR sensors and mechanical and electronic apparatuses. The AMR sensor senses disturbance of the earth magnetic field caused by a vehicle moving over the sensor and then produces an output indicative of the moving vehicle. In this paper, vehicle speeds are calculated by using two AMR sensors fixed on a board, with constant distance. To test and evaluate the accuracy of the detector in real traffic situations, the detector was installed on a local highway and vehicle speeds and volumes were measured both in a free running and a highly congested traffic. The measurements from the detector are compared with the reference measurements obtained from a traffic camera with the Mean Absolute Percentage Errors (MAPE), which has proved the usefulness of the detector in the field.