• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.8
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• pp.1507-1514
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• 2015

Non-orthogonal multiple access (NOMA) is a promising candidate for 5G networks. NOMA achieves superior spectral efficiency than conventional orthogonal multiple access (OMA), as in NOMA multiple users uses the same time and frequency resources. Multiple-input-multiple-output (MIMO) is one another promising technique that can enhance system performance. In this paper we present a spectral and energy efficient multiple antenna based NOMA scheme, known as spatially modulated NOMA. In the proposed scheme the cell edge users are multiplexed in spatial domain, which means the information to cell edge users is conveyed using the transmit antenna indices. In NOMA the performance of cell edge users are deeply effected as it treats signals of others as noise. The proposed scheme achieves superior spectral efficiency than the conventional NOMA. The number of decoding steps involved in decoding NOMA signal reduces by one as cell edge user is multiplexed in spatial domain. The proposed scheme is more energy efficient as compare to conventional NOMA. All of the three gains high spectral, energy efficiency and one step reduction in decoding comes at cost of multiple transmit antennas at base station.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37C no.11
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• pp.1077-1083
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• 2012

The jamming countermeasures in GNSS includes anti-jamming technique and jammer localization technique. In both techniques, direction of jamming signal is important and generally the MUSIC algorithm is used to find the direction of jamming signal. The MUSIC is super-resolution algorithm for detecting incident direction of signal. But, the search time of MUSIC algorithm is too long because all candidates of incidence angle are searched. This paper proposes the new method that has less computational burdens and therefore faster than the conventional MUSIC algorithm. The proposed method improves performance speed by reducing unnecessary calculations. In the proposed method, the cost function of conventional MUSIC algorithm is decomposed into the sum of squares and if the partial sum of cost function is larger than the minimum cost function so far, then the candidate is rejected and next candidates are searched. If the computed cost function is less than the minimum cost function so far, the minimum cost function so far is replaced with newly computed value. The performance of the proposed method was compared with the conventional MUSIC algorithm using the simulation. The accuracy of the estimaed direction of jamming signal was same as the conventional MUSIC while the search speed of the proposed method was 1.15 times faster than the conventional MUSIC.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.12
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• pp.521-528
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• 2017

Excessive alcohol consumption is one of the leading causes of many neurological diseases, such as dementia and Alzheimer's disease, and many efforts are under way to solve them. Red ginseng is known to enhance neuronal survival, inhibit apoptosis, and promote nerve regeneration of nerve cells. This study examined whether Rg3-enriched Korean red ginseng extract (KRG) inhibits the apoptosis of PC12 cells caused by alcohol-induced neurotoxicity and how KRG regulates several factors related to the caspase mediated pathway. In this way, the cell survival rate and apoptosis rate of PC12 cells were measured using an EZ-Cytox cell viability assay kit and flow cytometry, respectively. The expression of the apoptosis-related proteins (Bcl-2, Bid, Bax and caspase-3) were analyzed by western blotting, and the significance of the measured results was confirmed using the ANOVA method. As a result, KRG increased the expression of Bcl-2; inhibited the expression of Bid, Bax, and caspase-3; and inhibited the apoptosis of alcohol-induced PC12 cells. These results mean that the KRG-induced increase in Bcl-2 expression and down-regulation of Bid and Bax expression down-regulate caspase-3 expression, which in turn inhibits the mitochondrial apoptotic pathways. This study suggests that KRG is worth developing as a neuroprotective agent candidate.

• Journal of Satellite, Information and Communications
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• v.8 no.1
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• pp.23-30
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• 2013

In this study, we summarized the results of "Pre-study for the development of Polar route space radiation forecast model", funded by National Meteorological Satellite Center, Korea Meteorological Administration. We investigated the aviation space weather-related literature and the airline companies's operation manual associated with the space weather. We also identify the strengths and weaknesses of many pre-existing space radiation calculation programs, and find the potential to be improved. Until now, we don's have our own space radiation calculation program, so we need more improved space radiation calculation program which will be developed by ourselves. Currently most space radiation calculation programs cannot reflect temporary variations in the solar activities and the space weather. Here we analyzed the strengths and weaknesses of those programs, which are widely used in typical space radiation calculations. Finally to reflect the real-time space weather effects in the forecast model, we need to develop more precise forecast model. For that purpose, we suggest the following four steps: (1) at first, we have to choose the ground-based radiation dose calculation program, (2) we have to select a proper atmospheric model in aircraft altitude, (3) we combine the selected ground cosmic radiation dose calculation program and the selected atmospheric model, and finally (4)we have to reflect the real time space weather information and space weather forecast into the newly combined model.

• Journal of the Korean Society of Radiology
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• v.3 no.1
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• pp.11-15
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• 2009

In this study, the basic research verifying possibility of applications as radiology image sensor in Digital Radiography was performed, the radiology image sensor was fabricated using a multi-layer technique to decrease dark current. High efficiency materials in substitution for Amorphous Selenium(a-Se) have been studied as a direct method of imaging detector in Digital Radiography to decrease dark current by using PN junction or Hetero junction already used as solar cell, semiconductor. Particle-In -Binder method is used to fabricate radiology image sensor because it has a lot of advantages such as fabrication convenient, high yield, suitability for large area sensor. But high leakage current is one of main problem in Particle-In -Binder method. To make up for the weak points, multi-layer technique is used, and it is considered that high efficient digital radiation sensor can be fabricated with easy and convenient process. In this study, electrical properties such as leakage current, sensitivity, signal linearity is measured to evaluate multi-layer radiation sensor material.

• Journal of KIISE:Databases
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• v.34 no.5
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• pp.396-408
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• 2007

After the Human Genome Project finished the sequencing of a human DNA sequence, the concerns on protein functions are increasing. Since the structures of proteins are conserved in divergent evolution, their functions are determined by their structures rather than by their amino acid sequences. Therefore, if similarities between two protein structures are observed, we could expect them to have common biological functions. So far, a lot of researches on protein structure alignment have been performed. However, most of them use RMSD(Root Mean Square Deviation) as a similarity measure with which it is hard to judge the similarity level of two protein structures intuitively. In addition, they retrieve only one result having the highest alignment score with which it is hard to satisfy various users of different purpose. To overcome these limitations, we propose a novel protein structure alignment algorithm based on MRPD(Maximum of Residue Pair Distance) and SG (Similarity Graph). MRPD is more intuitive similarity measure by which fast tittering of unpromising pairs of protein pairs is possible, and SG is a compact representation method for multiple alignment results with which users can choose the most plausible one among various users' needs by providing multiple alignment results without compromising the time to align protein structures.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.8
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• pp.5070-5077
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• 2014

Many countries in the world have protected their native plants and utilized them as industrial materials in each country. In this aspect, it is increasingly important to develop cosmetics materials using native plants in Korea. Cosmetic materials have been developed with niche plants, such as Campanula takesimana Nakai, Dianthus superbus, Aster spathulifolius in Ullengdo, in which a specific plant distribution by distinct climate and environment was present. Water and ethanol extractions were performed from the calluses of Campanula takesimana Nakai, Dianthus superbus, Aster spathulifolius. HPLC analysis revealed different compositions and functions of effective elements in each ethanol extract. For example, all types of ethanol extracts showed an ability to heal wounds. In particular, the expression of the inflammation-related gene, COX-2, was decreased in response to the ethanol extracts of Dianthus superbus. These results indicate that the ethanol extracts from niche plants' calluses in Ullengdo are natural and environmentally-friendly compounds, and can be used as medical supplies associated with anti-inflammation and wound healing.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.5B
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• pp.512-521
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• 2003

In this paper, we introduce our experience of the design and implementation of mobile collaboration system(MCS) that support people using mobile devices to participate in cooperative session. There are considerable differences between desktop PC and mobile devices like PDA in processing ability, resolution of display and color degree. In the case of mobile devices, they use different processors and different operating system and they have even differences in ability of executing application. The mobile collaborative system based on T.120 protocol of ITU-T standard compromised of mobile collaboration server, mobile collaboration client, session node and application. We also define the session node in desktop PC in which session control block and communication block runs. This node provide functions of session control block and communication block to mobile collaboration clients and so lighten load of clients. The mobile collaboration server provides information of candidates for session node, session and user to mobile collaboration client. And this server support clients to configure their own session node and manage sessions. Only the mobile collaboration client module and applications including APE are executed in a mobile device when user using mobile devices would like to participate in cooperative session. We implemented mobile collaboration client and applications with JAVA to support platform independency.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.3 s.106
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• pp.307-316
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• 2006

In this paper the analytical method, namely advanced minimum coupling loss(A-MCL), was proposed in order to analyze the coexistence of OFDM-based systems beyond 3G(B3G) with point-to point(PP) fixed service(FS) microwave systems. Our proposed method is based on a power spectral density(PSD) analysis. So it can be easily applicable to analyze the coexistence of OFDM-based systems B3G using flexible spectrum usage(FSU) with other systems, where the conventional MCL method cannot allocate transmit power partially to some subcarriers which overlap the band of a victim system. By applying the conventional MCL method and the A-MCL method, interfering power levels at the receiver of a interfered system are respectively calculated. A-MCL can calculate interference power more accurately than MCL by the maximum value of 4.5 dB. Therefore it can be concluded that our prosed method, namely A-MCL, is applicable to a sharing analysis of OFDM-based systems B3G.

• Journal of the Korea Society of Computer and Information
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• v.17 no.3
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• pp.51-57
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• 2012

Hepatic vessel tree is the key structure for hepatic disease diagnosis and liver surgery planning. Especially, it is used to evaluate the donors' and recipients' liver for the LDLT(Living Donors Liver Transplantation) and estimate the volumes of left and right hepatic lobes for securing their life in the LDLT. In this study, we propose a method to apply canny edge detection that is not affected by noise to the liver images for automatic segmentation of hepatic vessels tree in contrast abdominal MDCT image. Using histograms and average pixel values of the various liver CT images, optimized parameters of the Canny algorithm are determined. It is more time-efficient to use the common parameters than to change parameters manually according to CT images. Candidates of hepatic vessels are extracted by threshold filtering around the detected the vessel edge. Finally, using a system which detects the true-negatives and the false-positives in horizontal and vertical direction, the true-negatives are added in candidate of hepatic vessels and the false-positives are removed. As a result of the process, the various hepatic vessel trees of patients are accurately reconstructed in 3D.