• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.10
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• pp.108-117
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• 2015

If typical contrast enhancement algorithms for natural images are applied to X-ray images, they may cause artifacts such as overshooting or produce unnatural visual quality because they do not consider inherent characteristics of X-ray images. In order to overcome such problems, we propose a locally adaptive block-based contrast enhancement algorithm for X-ray images. After we derive a weighted cumulative distribution function for each block, we apply it to each block for contrast enhancement. Then, we obtain images that are removed from block effect by adopting block-based overlapping. In post-processing, we obtain the final image by emphasizing high frequency components. Experimental results show that the proposed block-based contrast enhancement algorithm provides at maximum 5-times higher visual quality than the exiting algorithm in terms of quantitative contrast metric.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.47 no.11
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• pp.65-71
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• 2010

This paper presents a 14-band LO generator architecture for MB-OFDM UWB systems using 3.1 GHz~10.6 GHz frequency band. The proposed LO generator architecture has been consisted of only one PLL and the fewest nonlinear components to generate 14 LO signals with high purity while consuming low dc power consumption. In addition, major spurious generated from the LO generator have been located in the out of UWB band. The proposed LO generator has been implemented in a $0.13-{\mu}m$ CMOS technology and consumes a dc power consumption of 93~103 mW from a 1.5 V supply. The simulation results show an in-band spurious suppression ratio of more than 41 dBc and a band-switching time of below 3 nsec.

• Publications of The Korean Astronomical Society
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• v.13 no.1 s.14
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• pp.149-166
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• 1998

The structure and environments of the molecular clouds near the SNR $HB3(G132.7\pm1.3)$ are studied. The molecular complex which is located at the southern rim of HB3 was proposed by former investigators as the one interacting with HB3. This complex region of $2^{\circ}\times2^{\circ}\;at\;l=133^{\circ}$ has been observed at $^{12}CO,\;^{13}CO,\;J=1-0\;at\;a\;1'$, resolution with the 14-m radio telescope at Taeduk Radio Astronomy Observatory. We have reached to the following four conclusions. The possibility that these molecular complex and HB3 are interacting with each other cannot be supported with any of our data. The morphologies of the two show no similarities. Neither particular features for the interaction are found in the CO lines. The hypothetical 'Molecular wall' which was expected to exist on the northwestern rim of HB3 as a cause for the noncircular morphology of HB3 is turned out to be nonexistent in CO. The molecular complex which resembles a 'bar' at a low resolution is now resolved into a U-shaped shell. It seems that the U-shape is consist of two independent components. No peculiarities, such as unseen masses or bright stars capable of forming HlI regions, are found within the U-shape region. The total mass included in the complex is estimated to be $M_{total}\;=\;2.9\~8.4\times10^5\;M_\bigodot$, which is in good agreement with previous observations within errors. Considering about 12 clumps distinguishable within the complex, the total mass implies that masses of each of clumps are on the order of $10^4\;M_\bigodot$, which makes these good objects for further studies in relation to star-formation. Especially the clumps associated with W3 are worthy for more high resolution observations for better understanding of astrophysical phenomenon ongoing in them.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2010.10a
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• pp.206-208
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• 2010

We propose a retouching method that converts a photography taken by smartphone to a watercolor painting image using bilateral filtering and mean shift segmentation which are mostly used in image processing. The first step is to convert an input image to fit the screen resolution of smartphone. And next step is to weaken high frequency components of the image, while preserving the edge of image using the bilateral filtering. And after that we perform mean shift segmentation from the bilateral filtered image. We apply parameters of mean shift segmentation considering the processing speed of smartphone. Experimental result shows that our method can be applied to various types of image and bring better result.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.1C
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• pp.140-148
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• 2004

Natural images can be classified into edge or flat region. Edges have also various shapes such as long edge, texture and so on. Because the conventional deinterlacing methods commonly use one specific algorithm, they are faced with the difficulty that does not adapt various shapes of images. In this paper, a selective deinterlacing method based on the characteristics of local region of image is proposed. An input image is classified into three regions; flat region, complex edge, long edge. And then for each region, the proper method is assigned according to the characteristic of the local feature. For long edge region, the modified $NEDI(New Edge Directed Interpolation)^{[1]}$ method that interpolates long edge very well is used. The linear $filter^{[2]}$ that enhances high frequency components is used for complex edge, and the bilinear interpolation method is applied to flat region. The proposed method shows improved performance in PSNR and subjective evaluation compared with previous algorithms.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.2
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• pp.207-213
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• 2008

A simplified design procedure for quasi-Yagi antenna arrays using an ultra-wideband balun is presented. The proposed antenna design procedure is based on the simple impedance matching among antenna components: i.e., balun, feed, and antenna This new broadband and high gain antenna array is possible due to the ultra-wideband performance of the balun. As design examples, wideband $1\times4$ and $1\times8$ quasi-Yagi antenna arrays are successfully designed and implemented in Ku-band with frequency bandwidths of about 50 % and antenna gains of 9$\sim$10 dBi and 11$\sim$12 dBi, respectively. And the simulated and measured results demonstrate wide bandwidths and good radiation properties. These antenna arrays can be applied to various phased-array and spatial power combining systems.

• Journal of Broadcast Engineering
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• v.17 no.6
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• pp.911-923
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• 2012

Recently, 3DTV and 3D displays have been released in the market. Accordingly, the production of stereoscopic images has gained much interest. Stereoscopic image being composed of left and right images are currently delivered to viewers without any modifications. The researches on the enhancement of depth perception using high-frequency components and the re-production of natural color by color compensation have been carried out for 2D images. The application of such 2D technologies to 3D stereoscopic images is an aim of this paper. This paper proposes the enhancement of 3D perception by color transformation. For this, we propose a stereo matching method for obtaining a depth map and two color transformation methods such as contrast transformation and background darkening. The effectiveness of the proposed method was verified through experiments.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.15 no.6
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• pp.129-135
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• 2016

There have been many types of development and commercialization efforts for superconducting power applications with the continuous development of High Temperature Superconducting (HTS) conductors. In particular, HTS power cables are going to be commercialized in real power grids. A cryogenic refrigeration system should be used to keep it below 77 K, and its required cooling capacity continuously increases as the unit length of the HTS power cable increases. Among the many kinds of cryogenic refrigerator, a reverse Brayton refrigerator that uses turbo expanders is a promising refrigerator due to its efficiency and reliability. Among the various components in refrigerators, the cryogenic turbo-expander is the most important part for increasing efficiency and assuring reliability. The design of a 300 W class turbo-expander is described in this paper prior to the development of a 10 kW class turbo expander, which is the required capability for the commercialization of a HTS power cable. The impeller shape and rotation speed are determined based on the cycle analysis. The Eigen frequency and harmonic analysis are conducted with gas bearings at cryogenic temperatures to determine the operational stability.

• Journal of Korea Spatial Information System Society
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• v.11 no.3
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• pp.31-39
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• 2009

Requirement level regarding processing and managing real-time datastream in an ubiquitous environment is increased. Especially, due to the unbounded, high frequency and real-time characteristics of datastream, development of specialized stroge manager for DSMS is necessary to process such datastream. Existing DSMS, e.g. Coral8, can support datastream processing but it is not scalable and cannot perform well when handling large-volume real-time datastream, e.g. 100 thousand over per second. In the case of Oracle10g, which is generally used in related field, it supports storing and management processing. However, it does not support real-time datastream processing. In this paper, we propose specialized storage manager of DSMS for real-time compressed storing on semiconductor or LCD production facility of Samsung electronics, Hynix and HP. Hynix and HP. This paper describes the proposed system architecture and major components and show better performance of the proposed system compared with similar systems in the experiment section.

• Journal of Korean Medicine for Obesity Research
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• v.8 no.1
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• pp.81-88
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• 2008

Objectives To investigate the relationship between Heart Rate Variability and menopause among obese middle-aged women in Korea. Subjects and Methods Forty middle-aged women (age 49.05 $\pm$ 2.64 years) with BMI > $23kg/m^2$ were recruited by local advertisement. Blood profiles of estrogen, FSH, LH, glucose, total cholesterol, HDL-cholesterol, and triglyceride were measured. Autonomic Nervous System (ANS) was estimated by short-term spectral analysis of heart rate variability (HRV). Visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) were accessed using Computerized Tomography (CT), Bioimpedance Analysis (BIA), and anthropometry. To scrutinize the influence of ANS on obesity-related factors, we divided the subjects into pre- and post-menopausal women. Results The total cholesterol, FSH and LH were significantly higher in post-menopausal obese women group. The estradiol and standard deviation of all normal R-R intervals (SDNN), high-frequency components (HF) of the HRV were significantly lower in postmenopausal obese women group (P<0.05). Adipose tissue distribution and blood profiles were not significantly different between two groups. Conclusion Menopause induced a decrease in SDNN and HF values and increase in total cholesterol level in obese women although the VAT itself was not related with ANS in obese women.