• Korean Journal of Remote Sensing
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• v.38 no.6_1
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• pp.1015-1023
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• 2022

The Entry-Descent-Landing process of a lander involves many environmental and technical challenges. To solve these problems, recently, terrestrial relative navigation (TRN) technology has been essential for landers. TRN is a technology for estimating the position and attitude of a lander by comparing Inertial Measurement Unit (IMU) data and image data collected from a descending lander with pre-built reference data. In this paper, we present a method for generating descent dataset and extracting landmarks, which are key elements for developing TRN technologies to be used on Mars. The proposed method generates IMU data of a descending lander using a simulated Mars landing trajectory and generates descent images from high-resolution ortho-map and digital elevation map through a ray tracing technique. Landmark extraction is performed by an area-based extraction method due to the low-textured surfaces on Mars. In addition, search area reduction is carried out to improve matching accuracy and speed. The performance evaluation result for the descent dataset generation method showed that the proposed method can generate images that satisfy the imaging geometry. The performance evaluation result for the landmark extraction method showed that the proposed method ensures several meters of positioning accuracy while ensuring processing speed as fast as the feature-based methods.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.40 no.3
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• pp.43-53
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• 2003

Unlike in analog display devices, the physical screen resolution in digital devices are fixed from the manufacturing. It is a weak point on digital devices. The screen resolution displayed in digital display devices is varied. Thus, interpolation or decimation of the resolution on the display is needed to make the input pixels equal to the screen resolution., This process is called image scaling. Many researches have been developed to reduce the hardware cost and distortion of the image of image scaling algorithm. In this paper, we proposed a Winscale algorithm. which modifies the scale up/down in continuous domain to the scale up/down in discrete domain. Thus, the algorithm is suitable to digital display devices. Hardware implementation of the image scaler is performed using Verilog XL and chip is fabricated in a 0.5${\mu}{\textrm}{m}$ Samsung SOG technology. The hardware costs as well as the scalabilities are compared with the conventional image scaling algorithms that are used in other software. This Winscale algorithm is proved more scalable than other image-scaling algorithm, which has similar H/W cost. This image-scaling algorithm can be used in various digital display devices that need image scaling process.

• Journal of KIISE:Software and Applications
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• v.29 no.8
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• pp.521-528
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• 2002

We propose a new approach to the feature selection for the classification of handwritten characters using two-dimensional(2D) wavelet packet bases. To extract key features of an image data, for the dimension reduction Principal Component Analysis(PCA) has been most frequently used. However PCA relies on the eigenvalue system, it is not only sensitive to outliers and perturbations, but has a tendency to select only global features. Since the important features for the image data are often characterized by local information such as edges and spikes, PCA does not provide good solutions to such problems. Also solving an eigenvalue system usually requires high cost in its computation. In this paper, the original data is transformed with 2D wavelet packet bases and the best discriminant basis is searched, from which relevant features are selected. In contrast to PCA solutions, the fast selection of detailed features as well as global features is possible by virtue of the good properties of wavelets. Experiment results on the recognition rates of PCA and our approach are compared to show the performance of the proposed method.

• Journal of KIISE:Software and Applications
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• v.27 no.6
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• pp.632-641
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• 2000

Conventional character extraction methods extract character regions using methods such as color reduction, region split and merge and texture analysis from the whole image. Because these methods use many heuristic variables and thresholding values derived from a priori knowledge, it is difficult to generalize them algorithmically. In this paper, we propose a method that can extract character regions using a topographical feature extraction method and a point-line-region extension method. The proposed method can also solve the problems of conventional methods by reducing heuristic variables and generalizing thresholding values. We see that character regions can be extracted by generalized variables and thresolding values without using a priori knowledge of character region. Experimental results show that the candidate region extraction rate is 100%, and the character region extraction rate is over 98%.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.10B
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• pp.1979-1985
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• 1999

In this paper, we offer an analysis method for SL/D/1/K queueing system, where the shifting-level (SL) process proposed in the part I of this study[1]. Since an exact analysis of SL/D/1/K queueing system is very difficult, we propose an approximation method, where the queze sizes at input state transition epochs is quantized and thus the name 'quantization reduction method'. We provide the upper and lower bounds of the approximation for the system size distribution also, In addition, since the continuos version of well-known DAR(1) model is a kind of SL process with exponential correlation term only, the proposed method can be directly applied to the analysis of DAR(1)/D/1/K queueing system as well.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.2
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• pp.397-404
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• 2013

This paper propose the hardware architecture of face detection hardware system using the AdaBoost algorithm. The proposed structure of face detection hardware system is possible to work in 30frame per second and in real time. And the AdaBoost algorithm is adopted to learn and generate the characteristics of the face data by Matlab, and finally detected the face using this data. This paper describes the face detection hardware structure composed of image scaler, integral image extraction, face comparing, memory interface, data grouper and detected result display. The proposed circuit is so designed to process one point in one cycle that the prosed design can process full HD($1920{\times}1080$) image at 70MHz, which is approximate $2316087{\times}30$ cycle. Furthermore, This paper use the reducing the word length by Overflow to reduce memory size. and the proposed structure for face detection has been designed using Verilog HDL and modified in Mentor Graphics Modelsim. The proposed structure has been work on 45MHz operating frequency and use 74,757 LUT in FPGA Xilinx Virtex-5 XC5LX330.

• Journal of Broadcast Engineering
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• v.4 no.1
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• pp.76-85
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• 1999

The degradation of image quality by block loss is more serious in fractal coded images with the error propagation due to mapping from the lost blocks than in DCT coded images. Therefore. a new algorithm is presented for recovering the blocks lost in the transmission through the lossy network as A TM network of the images coded by Jacquins fractal coding. Jacquins fractal code is divided into two layers of header code and main code according to its importance. The key technique of the proposed BLRA (block loss recovery algorithm) is a fractal extrapolation that estimates the lost pixels by using the contractive mapping parameters of the neighboring range blocks whose characteristics are similar to a lost block. The proposed BLRA is applied to the lost blocks in the iteration of decoding. Some experimental results show the proposed BLRA yields excellent performance in PSNR as well as subjective quality.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.48 no.3
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• pp.99-105
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• 2011

In this paper, we proposed a method for estimating an accurate gamut based on segment maxima method. According to the number of segments in the segment maxima, a local concavity is generated in the vicinity of lightness axis or a gamut is reduced in high chroma region. It induces artifacts or deterioration of the image quality. To remove these artifacts, the number of segment is determined according to the number of samples. and a local concavity is modified by extending a detected concave point to the line connecting two adjacent boundary points. Experimental results show that the contours in a uniform color region and speckle artifacts from the conventional segment maxima algorithm are removed.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.43 no.3 s.309
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• pp.43-53
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• 2006

As wireless network technology has advanced, demands for multimedia contents through mobile environment have tendered to upward. Since network situation is changing every moment and types of user terminals are diverse, it is difficult for a content provider to consider network situation and type of user terminal to provide multimedia contents. As one solution, transcoding techniques have been proposed, but those have much complexity. In this paper, in order to reduce computational complexity, we propose a fast mode decision using input modes, motion vectors, and residual energies which are obtained from input bitstream for 2:1 down-scaling spatial transcoding application. The proposed method reduces processing time in mode decision by restricting possible mode types based on input information. Experimental results show that the proposed method achieves about 2.66 times improvement in encoding time compared to the normal encoding process while the PSNR is degraded by about 0.04dB, and bit-rate is increased by 1.6%.

• Journal of Korea Multimedia Society
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• v.7 no.7
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• pp.956-966
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• 2004

The Korean animation has enjoyed the brisk formation and establishment of its world-class infra for the last several years without unified titles or concepts, under the name of a national strategic project in the age of digital image. It also enjoys its new evaluation as digital animation that it's one of the greatest money making business in the non-education and frivolous culture and has the closest relations with the modern time. A great portion of popular image media has been taken by animation for the last 30 years. In this paper we propose a motion algorithm using an animation technology. It was developed for education purposed and accessible through the internet. For instance, in Cyber Clam Museum, 1000 gesture contents, the visual processes were used to design a screen with a realistic image and create an animation that makes possible show at 360 and every such transformation as translation, rotation, and scaling can be applied in the image interactively for the convenient and effective viewing.