• Journal of the Institute of Electronics Engineers of Korea SP
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• v.43 no.2 s.308
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• pp.30-39
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• 2006

Iris recognition is that identifies a user based on the unique iris texture patterns which has the functionalities of dilating or contracting pupil region. Iris recognition systems extract the iris pattern in iris image captured by iris recognition camera. Therefore performance of iris recognition is affected by the quality of iris image which includes iris pattern. If iris image is blurred, iris pattern is transformed. It causes FRR(False Rejection Error) to be increased. Optical defocusing is the main factor to make blurred iris images. In conventional iris recognition camera, they use two kinds of focusing methods such as lilted and auto-focusing method. In case of fixed focusing method, the users should repeatedly align their eyes in DOF(Depth of Field), while the iris recognition system acquires good focused is image. Therefore it can give much inconvenience to the users. In case of auto-focusing method, the iris recognition camera moves focus lens with auto-focusing algorithm for capturing the best focused image. However, that needs additional H/W equipment such as distance measuring sensor between users and camera lens, and motor to move focus lens. Therefore the size and cost of iris recognition camera are increased and this kind of camera cannot be used for small sized mobile device. To overcome those problems, we propose method to increase DOF by iris image restoration algorithm based on focus value of iris image. When we tested our proposed algorithm with BM-ET100 made by Panasonic, we could increase operation range from 48-53cm to 46-56cm.

• Journal of Broadcast Engineering
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• v.5 no.2
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• pp.239-246
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• 2000

An efficient control parameter extraction scheme required for auto-focusing control of a stereo camera is proposed. Without loss of generality, it is assumed that an interesting object exists in the center of a captured image by a stereo camera. In such a case. we apply a 2-dimensional wavelet transform to the center area with specific image size in the captured image. Next, we extract required focus control parameters using an Ll-norm for doubly high-pass filtered components. Experimental results show that the proposed scheme is effectively applicable to the auto-focusing for a stereo camera compared to the conventional control scheme using discrete cosine transform (DCT).

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.41 no.5
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• pp.235-249
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• 2004

This paper proposes a method for estimating isotropic out-of-focus blur and a fully digital auto-focusing based on a priori estimate set of PSFs. The proposed algorithm for identifying the isotropic PSF is performed by approximating an isotropic blur to a novel discrete PSF model and estimating the PSF model coefficients from degraded edges. After acquiring the set of PSFs by proposed PSF estimation algorithm the proposed fully digital auto-focusing system can restore out-of-focused images by two steps: i) selecting an optimal PSF and ii) restoring the out-of-focused image by digital image restoration.

• IEIE Transactions on Smart Processing and Computing
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• v.1 no.3
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• pp.133-142
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• 2012

This paper presents a salient region detection algorithm for auto-focusing based on the characteristics of a human's visual attention. To describe the saliency at the local, regional, and global levels, this paper proposes a set of novel features including multi-scale local contrast, variance, center-surround entropy, and closeness to the center. Those features are then prioritized to produce a saliency map. The major advantage of the proposed approach is twofold; i) robustness to changes in focus and ii) low computational complexity. The experimental results showed that the proposed method outperforms the existing low-level feature-based methods in the sense of both robustness and accuracy for auto-focusing.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.05a
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• pp.320-323
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• 2011

The compact camera assembled into Smart phone is required to have higher resolution level in non AF state than existing handsets, and it is also requested to have higher degree of accuracy, more consistent repetitiveness, and faster auto focusing speed. Algorithm based on a mechanical position of the existing actuator has been discussed. Therefore, in this thesis I suggest an improved algorithm concerning the problem of unstable resolution level in non AF state and auto focusing speed.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.5 no.5
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• pp.438-441
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• 2004

In this paper, an apparatus for unbinding the rope is studied to solve continuous work of the auto cleaning apparatus of a pillar. During operation of the auto cleaning apparatus of a pillar, in order to not swing the apparatus is down by it's weight according as electric motor velocity. We focus on the design and the implementation to upgrade the auto cleaning apparatus of a pillar that had been implemented.

• ETRI Journal
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• v.29 no.6
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• pp.817-819
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• 2007

A low-stress organic polymer membrane is proposed as a deformable mirror that can be incorporated into a cellular phone camera to achieve auto focusing without motor-type moving parts. It is demonstrated that our fabricated device has an optical power of 20 diopters and can switch focus in 14 ms. The surface roughness of the organic membrane is measured around 15 nm, less than ${\lambda}$/20 of the visible light. With curve fitting, we found that the actuated membrane is almost parabolic in shape, which leads to less aberration than spherical surfaces. It is suitable for reflective-optics systems.

• Transactions of the Society of Information Storage Systems
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• v.9 no.2
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• pp.56-61
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• 2013

The recent increased use of mobile phone has resulted in a technical focusing on reliability issues related to drop performance. Since mobile phone may be dropped several times during their use, it is required to survive common drop accidents. The plastic injection parts such as base stopper and carrier in the encoder type actuator can be broken easily in the actual reliability test of 1.5m free drop. So, we analyzed the shock resistance characteristics of auto focus actuator with variables in the material properties using finite element method. By applying the new resin materials, we can decrease the breakage of plastic injection parts and improve the reliability of mobile phone.

• Proceedings of the IEEK Conference
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• 2003.07e
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• pp.1727-1730
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• 2003

In this paper we propose a sub-pixel point spread function (PSF) estimation method for a fully digital auto-focusing system. We assume that the amount of out-of-focus is the same along the concentric circle. In order to estimate the accurate PSF, sub-pixel information is considered in the proposed PSF estimation procedure. The feasibility of the proposed algorithm is experimentally demonstrated.

• Journal of the Korean Society for Precision Engineering
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• v.27 no.2
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• pp.34-39
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• 2010

In order to achieve and maintain dimensional accuracy in laser micro-machining, dominant parameters such as laser power and laser focus position need to be monitored and controlled real time. Also, in order to selectively machine multi-layered materials, the material being presently machined need to be recognized. This paper presents an auto-focusing (AF) module to keep laser focus on a large-area surface; a real-time laser power stabilizing module based on optical attenuation; and a laser-induced breakdown spectroscopy (LIBS) module. With these monitoring modules, position error in laser focus on a 4" silicon wafer was kept below $4{\mu}m$, initially $51{\mu}m$, and laser power stability of a UV laser source was improved from 1.6% to 0.3%. Also, the material transition from polyimide to copper in machining of FCCL (flexible copper clad laminate) was successfully observed.