• Journal of Sensor Science and Technology
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• v.14 no.4
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• pp.278-285
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• 2005

This paper describes techniques of camera calibration and artificial landmarks detection for the automatic charging of a mobile robot, equipped with a fish-eye camera in the direction of its operation for movement or surveillance purposes. For its identification from the surrounding environments, three landmarks employed with infrared LEDs, were installed at the charging station. When the robot reaches a certain point, a signal is sent to the LEDs for activation, which allows the robot to easily detect the landmarks using its vision camera. To eliminate the effects of the outside light interference during the process, a difference image was generated by comparing the two images taken when the LEDs are on and off respectively. A fish-eye lens was used for the vision camera of the robot but the wide-angle lens resulted in a significant image distortion. The radial lens distortion was corrected after linear perspective projection transformation based on the pin-hole model. In the experiment, the designed system showed sensing accuracy of ${\pm}10$ mm in position and ${\pm}1^{\circ}$ in orientation at the distance of 550 mm.

• Advances in aircraft and spacecraft science
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• v.10 no.1
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• pp.67-82
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• 2023

Linear array imaging sensors are widely used in remote sensing satellites. The final products of an imaging sensor can only be used when they are geometrically, radiometrically, and spectrally calibrated. Therefore, at the first stages of sensor design, a detailed calibration procedure must be carefully planned based on the accuracy requirements. In this paper, focusing on inherent optical distortion, a step-by-step procedure for laboratory geometric calibration of a typical push-broom satellite imaging sensor is simulated. The basis of this work is the simulation of a laboratory procedure in which a linear imager mounted on a rotary table captures images of a pin-hole pattern at different angles. By these images and their corresponding pinhole approximation, the correction function is extracted and applied to the raw images to give the corrected ones. The simulation results illustrate that using this approach, the nonlinear effects of distortion can be minimized and therefore the accuracy of the geometric position of this method on the image screen can be improved to better than the order of sub-pixel. On the other hand, the analyses can be used to proper laboratory facility selection based on the imaging sensor specifications and the accuracy.

• The Korean Journal of Nuclear Medicine
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• v.37 no.3
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• pp.137-146
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• 2003

Rheumatic diseases can be categorized by pathology into several specific types of musculoskeletal problems, including synovitis (e.g. rheumatoid arthritis), enthesopathy (e.g. ankylosing spondylitis) and cartilage degeneration (e.g. osteoarthritis). Skeletal radiographs have contributed to the diagnosis of these articular diseases, and some disease entities need typical radiographic changes as a factor of the diagnostic criteria. However, they sometimes show normal radiographic findings in the early stage of disease, when there is demineralization of less than 30-50 %. Bone scans have also been used in arthritis, but not widely because the findings are nonspecific and it is thought that bone scans do not add significant information to routine radiography. Bone scans do however play a different role than simple radiography, and it is a complementary imaging method in the course of management of arthritis. The Image quality of bone scans can be improved by obtaining regional views and images under a pin-hole collimator, and through a variety of scintigraphic techniques including the three phase bone scan and bone SPECT. Therefore, bone scans could improve the diagnostic value, and answer multiple clinical questions, based on the pathophysiology of various forms of arthritis.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.6
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• pp.552-557
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• 2006

Electrical, optical, surface, and structural properties of amorphous indium-zinc-oxide (a-IZO) grown by box cathode sputtering (BCS) were compared with crystalline indium-tin-oxide (c-ITO) anode films grown by conventional DC sputtering (DCS). Although x-ray diffraction plot of BCS-grown IZO film shows amorphous structure, the optical and electrical properties of a-IZO is comparable to those of c-ITO film. In particular, BCS-grown IZO films shows very smooth surface without defects such as pin hole and cracks because most of the energy of the sputtered atoms was confined in high density plasma region in box cathode gun. Furthermore polymer organic light emitting diodes (POLED) with the a-IZO anode film shows better electrical properties than that of POLED with the c-ITO anode film due to high work function and smooth surface of a-IZO. This suggested that BCS-grown a-IZO film is promising anode materials substituting conventional c-ITO anode in OLED and flexible displays.

• Proceedings of the KIEE Conference
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• 2001.07c
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• pp.1540-1542
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• 2001

In this paper, the amount of additives in the electrode were investigated the relation of the mechanical properties and surface luminance of copper foil. Especially, organic compound of PEG(Poly-ethylene Glycol) was added from 1 to 20ppm for the propose of increasing the mechanical property and the surface state. The surface luminance of copper foil is appealed 69.25 at 2ppm-15A/$dm^2$ and 68.25 at 2ppm-10A/$dm^2$. It guess that 10ppm-10A/$dm^2$ occurred pin-hole. Tensile strength was not showed the significant difference but elongation appealed the most value at 5ppm-15A. We earned that the most PEG value of mechanical properties is 5 PPM.

• Journal of the Korea Computer Graphics Society
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• v.14 no.2
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• pp.1-8
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• 2008

This paper presents a design of a situation training system supporting mixed-reality for the developmental disabled. The training scenario is developed for the disabled to improve the sense of sight and perception. The user sticks a virtual pin into a hole in the working board according to the direction and the appropriate feedback is delivered based on the FSM(Finite State Machine). In order to improve the reality and the training effect, the user's hand is inserted in the virtual training environments and the tactile sensation is provided using the haptic device.

• International Journal of Air-Conditioning and Refrigeration
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• v.13 no.4
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• pp.196-205
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• 2005

In this paper, recent research trend on heat transfer in impinging jet is reviewed. We focused on submerged jet that air issued into air or liquid issued into liquid. To control and enhance the heat transfer in single jet, researchers have performed a lot of experiments by considering the nozzle geometry, impinging surface and active method such as jet vibration, secondary injection and suction flow. The studies on multiple jet have been mainly focused on finding out the optimum condition and on investigating many different factors concerned with application condition (crossflow, rotation and geometry etc.) and combined techniques (rib turbulator, pin fin, dimple and effusion hole etc.). All most experiments showed the detailed heat transfer data by using liquid crystal method, infrared camera technique and naphthalene sublimation method. Many numerical calculations have been performed to investigate the flow and heat transfer characteristics in laminar jet region. Various turbulence models such as $k-\varepsilon-\bar{\nu^2}$, modified $k-\varepsilon-f_{\mu}$ were applied to the calculation for turbulent jet and the predicted results showed a good agreement with the experimental data. Although a lot of studies on impinging jet have performed consistently up to recently, further studies are still required to understand the flow and heat transfer characteristics more accurately, and to give a guideline for optimum impinging jet design in various applications.

• Proceedings of the KSME Conference
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• 2001.06b
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• pp.228-234
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• 2001

NTMS(Non-contact Tilted-angle Measuring System) is developed by using the principle that the magnetic field of an anisotropic magnet's inner space is uniform and it's possible to measure the strength of the magnetic field using a linear hall effect sensor. In order to implement the caliper system of the geometry PIG(Pipeline Inspection Gauge) which has high accuracy and proper output voltage of the hall sensor without additional driving module or a signal amplifier, it is necessary to consider the size of the magnet, the inner space and back-yoke and the position of pin-hole in the magnet. So the optimal design method of the caliper system is proposed through analysis of NTMS's magnetic field adopting a FEM(Finite Element Method). The experimental results show that the developed caliper system can be used for the geometry pig with good performances.

• Journal of the Korean institute of surface engineering
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• v.49 no.3
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• pp.238-244
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• 2016

Copper electrodeposition on AZ91 Mg alloy was studied in views of preferential deposition on ${\alpha}$- or ${\beta}$- phases and how to achieve uniform deposition over the entire surface on ${\alpha}$- and ${\beta}$-phases in a cyanide solution. The inhomogeneous microstructure of AZ91 Mg alloy, particularly ${\alpha}$- and ${\beta}$-phases, was found to result in non-uniform deposition of zincate layer, preferential deposition of zincate on ${\beta}$-phases, which leads to non-uniform growth of copper layer during the following electrodeposition process. The preferential depositions of zincate can be attributed to higher cathodic polarizations on the ${\beta}$-phases. Pin-hole defects in the copper electrodeposit were observed at the center of large size ${\beta}$-phase particles which is ascribed to gas bubbles formed at the ${\beta}$-phases. The activation of AZ91 Mg alloy in hydrofluoric acid solution was used to obtain uniform growth of zincate layer on both the ${\alpha}$- and ${\beta}$-phases. By choosing an optimum activation time, a uniform zincate layer was obtained on the AZ91 Mg alloy surface and thereby uniform growth of copper was obtained in a cyanide copper electroplating solution.

• Journal of the Korean Society for Nondestructive Testing
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• v.30 no.3
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• pp.181-193
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• 2010

The paper presents an alternative way to classical stereocorrelation. First, 2D image processing of random patterns is described. Sub-pixel displacements are determined using phase analysis. Then distortion evaluation is presented. The distortion is identified without any assumption on the lens model because of the use of a grid technique approach. Last, shape measurement and shape variation is caught by fringe projection. Analysis is based on two pin-hole assumptions for the video-projector and the camera. Then, fringe projection is coupled to in-plane displacement to give rise to 3D measurement set-up. Metrological characterization shows a resolution comparable to classical (stereo) correlation technique ($1/100^{th}$ pixel). Spatial resolution seems to be an advantage of the method, because of the use of temporal phase stepping (shape measurement, 1 pixel) and windowed Fourier transform (in plane displacements measurement, 9 pixels). Two examples are given. First one is the study of skin properties; second one is a study on leather fabric. In both cases, results are convincing, and have been exploited to give mechanical interpretation.