• The KIPS Transactions:PartB
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• v.11B no.7 s.96
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• pp.821-830
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• 2004

In this paper, we model the downward collision of a falling object to the base. We aim to provide maximum diversity of response to physical. collision. To this end, the primary design concern of the model is to unfold the collision phenomenon in a logical and natural manner, detailed enough to construct an immersive virtual environment. To achieve these requirements, first we determine domains for the characteristic of the material of the falling objects, and select the dominant force of the collision. We formulate the collision phenomena with combination of primitive attributes and their relationships. The formulated function evaluates the results of the collision in qualitative aspects as well as in quantitative aspects. Between the collision issues, 'Collision Detection' and 'Collision Response', this paper focuses on Collision Response issue.

• Korean Journal of Optics and Photonics
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• v.12 no.3
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• pp.165-171
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• 2001

We discuss the influence of annular binary filters on the axial PSF of imaging systems which are apodized by a radiallysymmetric filter and have spherical aberration and coma. In this paper we consider a whole family of annular binary fIlters in two cases. First, the binary filters are composed of two transparent annuli of the same area. Second, the binary filters are composed of a central clear circle and a concentric annular aperture with area bigger than that of the inner circle. In order to investigate the influence of the proposed filters on the axial PSF, we may use the axial resolution gains, which evaluate in terms of the FWHM of the intensity in the focal region of an apodized imaging system in comparison with that corresponding to a nonapodized one. We evaluate the PSF for the conventional and confocal systems having an aberration. ation.

• Journal of Sensor Science and Technology
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• v.10 no.5
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• pp.337-342
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• 2001

Infrared sensors with one or two dimensional arrays are usually bonded via indium bumps to Si CMOS read out circuits. Therefore, both sensing of infrared beams and processing of signals are performed at the focal plane. This gives us a benefit of reducing noise as well as size of infrared detectors. We have developed a way of boding indium bumps with keeping sensor and ROIC parallel to each other. The flip chip bonder developed has a very simple structure and is easy to operate. So we expect that reliability will be improved very much.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.10 no.2
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• pp.207-217
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• 1999

When the feed of an offset reflector antenna is displaced from the focal point, the phase distortion results in the aperture field distribution, which in turn gives rise to a deviation of maximum beam, a decrease in gain, and an increase in sidelobes. In order to study these scan characteristics, an offset reflector antenna with the defocused feed is analyzed by a series expansion method using the Zernike polynomials, which can be used to calculate radiation pattern fast and exactly. And from the analyzed results, scan loss data in terms of reflector geometry are presented. And also, the BDF (beam deviation factor) expression is derived with offset reflector configuration analytically, and calculated results and simple formula of BDF are presented for determining beam deviation characteristics.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.37 no.3
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• pp.63-71
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• 2000

Infrared (IR) detector chip, which detects the IR radiation from all of the objects and converts to image signal, is usually fabricated using hybrid bonding technology with detector away and readout integrated circuit (ROIC). In this study, we designed the readout circuit and simulated its operations. Fabricating readout circuit chips, we measured operation results satisfying its design requirements in 6V supply voltage. After we mount the IR detector chip in the manufactured thermal image system, thermal images were implemented. The obtained thermal images for high and room temperature target objects are sufficiently recognizable. Using the low noise thermal Image system, we expect to obtain thermal images with higher temperature resolution.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.12
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• pp.1886-1891
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• 2012

In this paper, the analytical models for the electrothermal feedback of a ${\mu}$-bolometer focal plane array(FPA) are proposed and applied to the conceptually designed FPA to investigate the electrothermal feedback effect on bolometer FPA signal. The temperature and resistance change of the ${\mu}$-bolometer by the electrothermal feedback(ETF) model are increased upto 20 and 35.7 % of those of no feedback case, respectively, while those by the effective thermal conductance(ETC) model increased 8.5 and 15.1 %. The integration current and output voltage of a CTIA used as an column amplifier of FPA are also increased upto 41.6 and 32.4 % by the ETF model, while increased upto 17.2 and 13.5 % by the ETC model. The proposed models give more accurate temperature change, accordingly larger signal than no feedback considering case. Electrothermal feedback effect should be considered to design a high performance and high density ${\mu}$-bolometer FPA. The proposed models are very useful to investigate the transient thermal analysis, also considered to be useful to predict the responsivity and dynamic range of ${\mu}$-bolometer FPAs.

• Journal of Convergence Society for SMB
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• v.6 no.3
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• pp.85-91
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• 2016

It was difficult to verify the car number or face of inspector in the closed circuit television because of low CCD pixels and low brightness of lens. So CCTV lens should have higher pixels and brightness. In this paper, the design of zoom lens for mega pixel Closed-Circuit Television (CCTV) was introduced. We applied aspheric lens in order to reduce the spherical aberration and distortional aberration. And we applied focal length of 6-60mm, F number of 1.2, 3 million pixel resolution and magnifying power of 10 times. Also we applied infrared correction in order to use the CCTV camera in day and night effectively. These norms are the most powerful in CCTV zoom lens of focal length of 6-60mm. And if we apply this lens to the box style CCTV camera, we can verify the car number or face within 50m. Auto controlling system will be continued.

• The Journal of the Acoustical Society of Korea
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• v.37 no.6
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• pp.443-450
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• 2018

A receiving array system can be applied for tonal noise analysis of underwater vehicles, but it is difficult to install and operate, and a lot of cost is required. In order to overcome this problem, this paper proposes a method to measure the tonal noise of underwater vehicle after synthesizing a virtual array using single receiver. The proposed method compensates the Doppler frequency and time delay caused by the movement of the underwater sound source and applies the focused beamforming technique. The performance of the proposed method was analyzed via simulation.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.23 no.3
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• pp.398-407
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• 1999

In the present image processing technique, the concept of the gradient indicator(GI) has been introduced to find out the depth-of-field in sizing large particles ranging from $30{\mu}m$ to $30{\mu}m$ where using of the concept of the normalized contrast value(VC) is not appropriate. The gradient indicator is defined as the ratio of the local value to the maximum possible value of the gray-level gradient in an image frame. The gradient indicator decreases with the increases of the particle size and the distance from the exact focal plane. A particle is considered to be in focus when the value of the gradient indicator at its image boundary stays above a critical value. This critical gradient indicator($GI_{critical}$) is defined as the maximum gradient indicator($GI_{max}$) subtracted by a constant ${\Delta}GI$ which is to account for the particle-size effect. In the present ca.so, the value of ${\Delta}GI$ was set to 0.28 to keep the standard deviation of the measured particles mostly within 0.1. It was also confirmed that, to find the depth-of-field for small particles(${\leq}30{\mu}m$) with the same measurement accuracy, tho concept of the critical normalized contrast($VC_{critical}$) is applicable with 85% of the maximum normalized contrast value($VC_{max}$). Finally, the depth-of-field was checked for the size range between $10{\mu}m$ and $300{\mu}m$ when the both in-focus criteria ($GI_{critical}$ and $VC_{critical}$) were adopted. The change of the depth-of-field with the particle size shows good linearity in both the VC-applicable and the GI-applicable ranges with a reasonable accuracy.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.3 s.357
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• pp.105-110
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• 2007

We have built the millimeter-wave passive imaging system with a lens and mechanical scan antenna. The lens was designed based on optical theory in order to focus millimeter-wane. A full image was taken from image points scanned by Placing antenna at the representative focal plane selectively. An integrated antenna array device for low-loss and low-noise with the array of 4 by 1, where components such as antenna, balun, MMIC, and detector were assembled on a sin91e substrate, and a fermi tapered slot antenna with high-gain and low-side lobe were used for elements of this millimeter-wave passive imaging system. Two dimensional antenna arrangement on focal plane was achieved in this imaging system.