• Journal of the Institute of Convergence Signal Processing
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• v.10 no.3
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• pp.151-157
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• 2009

In this paper, we proposed an algorithm of redeye correction. For naturally redeye correction, we assumed positions of the redeye at an image which produced redeye, and we estimated rate of the redeye to apply the appropriate redeye correction suitably. We extract and label pixels those are possible of generating redeye using red, skin and reflected light color. The each labeled group is decided by rates of length and width, dimension, density, the color of white of the eye and reflected light color of groups for the redeye group. We corrected positions of redeye using blurring effect, naturally. In the case of designing the proposed algorithm, we designed the redeye correction hardware using the minimum of memories for efficiency of hardware.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.34S no.1
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• pp.94-104
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• 1997

Most color imaging devices often exhibit color distortions due to the differences in realizable color gamuts and nonlinear characteristics of their components. In order to minimize color differences, it is desirable to apply color correction techniques. Th efirst step of color correction is to select the subset of the color coordinates representing the input color space. Th eselected subset serves as so called color samples to model the color distortion of a given color imaging device. The effectiveness of color correction is determined by the color sampels utilized in the modeling as well as the applied color correction technique. This paper presents a new selection method for color samples based on gentic algorithm. In the proposed method, structure of strings are designed so that the selected color samples fully represent the characteristics of color imaging device and consist of distinct color coordinates. To evaluate the performance of the selected color samples, they ar etuilized for three different color correction experiments. The experimentsal results are comapred with the crresponding results obtianed with the equally spaced color samples.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.11
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• pp.42-50
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• 2001

In this paper, a new technique and theory are proposed which correct the orientation (inclination of a vertical axis) of a cylinder in vertical-micro positioning device. An algorithm for determining the orientation of the cylinder with a pair of displacement sensor units is derived and two types of the correction methods are described. To assess the performance and efficiency of the developed correction technique, the compensation errors originated from the correction algorithm and the machined characteristics of cylinder surface are evaluated from the geometrical considerations and the statistical techniques. Based upon the evaluation results, the maximum compensation error is estimated for the orientation of cylinder and the optimum correction technique is derived.

• Journal of the Semiconductor & Display Technology
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• v.19 no.3
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• pp.112-117
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• 2020

NAND flash memory is a non-volatile memory that retains stored data even without power supply. Internal memory used as a data storage device and solid-state drive (SSD) is used in portable devices such as smartphones and digital cameras. However, NAND flash memory carries the risk of electric shock, which can cause errors during read/write operations, so use error correction codes to ensure reliability. It efficiently recovers bad block information, which is a defect in NAND flash memory. BBT (Bad Block Table) is configured to manage data to increase stability, and as a result of experimenting with the error correction code algorithm, the bit error rate per page unit of 4Mbytes memory was on average 0ppm, and 100ppm without error correction code. Through the error correction code algorithm, data stability and reliability can be improved.

• Journal of Korea Society of Digital Industry and Information Management
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• v.15 no.1
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• pp.99-107
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• 2019

Retinex-based image enhancement is a technique that utilizes the property that the human visual characteristics are sensitive to the difference from the surrounding pixel value rather than the pixel value itself. These Retinex-based algorithms show different characteristics of the improved image depending on the applied color space or gamma correction. In this paper, we set eight different experimental conditions according to the application of color space and gamma correction, and analyze the objective and subjective performance of each Retinex based image enhancement algorithm and apply it to the implementation of Retinex based algorithm. In the case of gamma correction, quantitative low entropy images and low contrast images are obtained. The application of Retinex technique in HSI color space rather than RGB color space is found to be high in overall subjective image quality as well as maintaining color.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.15 no.2
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• pp.485-499
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• 2021

Although non-binary low-density parity-check (NB-LDPC) codes have better error-correction capability than that of binary LDPC codes, their decoding complexity is significantly higher. Therefore, it is crucial to reduce the decoding complexity of NB-LDPC while maintaining their error-correction capability to adopt them for various applications. The extended min-sum (EMS) algorithm is widely used for decoding NB-LDPC codes, and it reduces the complexity of check node (CN) operations via message truncation. Herein, we propose a low-cost CN processing method to reduce the complexity of CN operations, which take most of the decoding time. Unlike existing studies on low complexity CN operations, the proposed method employs quick selection algorithm, thereby reducing the hardware complexity and CN operation time. The experimental results show that the proposed selection-based CN operation is more than three times faster and achieves better error-correction performance than the conventional EMS algorithm.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.1
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• pp.69-77
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• 1998

Linear displacement accuracy is one of the most important factors that determine machine tool accuracy The laser interferometer has been usually recommended for the measurement of linear displacement accuracy. In this paper, microcomputer aided measurement and compensation system has been developed for the pitch error in a CNC machine tool. For accurate pitch error calculation. the analysis code for the pitch error has been also implemented according to the international standards (ISO). The PC based automatic compensation system for the pitch error is also implemented. A new algorithm for calculating optimum value for pitch error compensation is proposed, minimizing the deviation at each target points. The development system has been applied to a practical CNC maching center and the performance has been demonstrated.

• Journal of Positioning, Navigation, and Timing
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• v.3 no.1
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• pp.17-23
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• 2014

Satellite Based Augmentation Systems (SBAS) provide ionospheric corrections at geographically five degree-spaced Ionospheric Grid Points (IGPs) and confidence bounds, called Grid Ionospheric Vertical Errors (GIVEs), on the error of those corrections. Since the ionosphere is one of the largest error sources which may threaten the safety of a single frequency Global Navigation Satellite System (GNSS) user, the ionospheric correction and integrity bound algorithm is essential for the development of SBAS. The current single frequency based SBAS, already deployed or being developed, implement the ionospheric correction and error bounding algorithm of the Wide Area Augmentation System (WAAS) developed for use in the United States. However, the ionospheric condition is different for each region and it could greatly degrade the performance of SBAS if its regional characteristics are not properly treated. Therefore, this paper discusses key factors that should be taken into consideration in the development of the ionospheric correction and integrity bound algorithm optimized for the Korean SBAS. The main elements of the conventional GIVE monitor algorithm are firstly reviewed. Then, this paper suggests several areas which should be investigated to improve the availability of the Korean SBAS by decreasing the GIVE value.

• Journal of Korea Multimedia Society
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• v.19 no.5
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• pp.837-847
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• 2016

Tone mapping for High Dynamic Range(HDR) image provides matching human visual perception between real world scene and displayable devices. Recently, a tone mapping algorithm based on localized gamma correction is proposed. This algorithm is using human visual properties of contrast and colorfulness with background intensity, generating a weight map for gamma correction. However, this method have limitations of controlling enhancement region as well as generating halo artifacts caused by the weight map construction. To overcome aforementioned limitations, proposed algorithm in this paper modifies previous weight map, considering base layer intensity of input luminance channel. By determining enhancement region locally and globally based on base layer intensity, gamma values are corrected accordingly. Therefore, proposed algorithm selectively enhances local brightness and controls strength of edges. Subjective evaluation using z-score shows that our proposed algorithm outperforms the conventional methods.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.7
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• pp.1017-1024
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• 2017

The International Electrotechnical Commission(IEC) 61000-4-15 is a standard proposing techniques for a flicker meter test and measurement method. The IEC61000-4-15 ed1 announced in 1997 was not include tests for accurate verification. Also it was not explained flicker meter algorithm that can be directly applied to the other power systems. But the new edition of IEC61000-4-15 ed2 prescribes a variety of tests for verify flicker meter algorithm and it explains 'correction factor' used for measuring flicker in other power systems. It can measure flicker severity in 220V system by multiplying correction factor to the measured values with the 230V algorithm. This paper compared the method of measuring flicker severity in korea power system using the correction factor and the modified weighting filter, after verifying of digital flicker meter algorithm created by using matlab based on IEC61000-4-15 ed2.