• Journal of Communications and Networks
• /
• v.18 no.3
• /
• pp.439-445
• /
• 2016

In this paper, we consider subcarrier-index modulation (SIM) for precoded orthogonal frequency division multiplexing (OFDM) with a few activated subcarriers per user and its generalization to multi-carrier multiple access systems. The resulting multiple access is called sparse index multiple access (SIMA). SIMA can be considered as a combination of multi-carrier code division multiple access (MC-CDMA) and SIM. Thus, SIMA is able to exploit a path diversity gain by (random) spreading over multiple carriers as MC-CDMA. To detect multiple users' signals, a low-complexity detection method is proposed by exploiting the notion of compressive sensing (CS). The derived low-complexity detection method is based on the orthogonal matching pursuit (OMP) algorithm, which is one of greedy algorithms used to estimate sparse signals in CS. From simulation results, we can observe that SIMA can perform better than MC-CDMA when the ratio of the number of users to the number of multi-carrier is low.

• Journal of the Korean Society of Tobacco Science
• /
• v.16 no.1
• /
• pp.20-25
• /
• 1994

The volatile components were extracted from root of Cnidium officinale M. by SDE(Simultaneous steam distillation and extraction) apparatus and analyzed by GC/M.5 and GC retention index matching. The experimental results revealed the presence of over 22 volatile components. Major components were cnidilide (35.1%), neocnidilids (13.4%), ligustilide (23.2%). The essential oils were separated by silica gel column chromatography(Merck 70-230mesh), and 4 fractions among 12 fractions separated had a, good aroma character.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.8 no.8
• /
• pp.2913-2929
• /
• 2014

Traditional vector quantization (VQ) schemes encode image blocks as VQ indices, in which there is significant similarity between the image block and the codeword of the VQ index. Thus, the method can compress an image and maintain good image quality. This paper proposes a novel lossless VQ indices compression algorithm to further compress the VQ index table. Our scheme exploits the high correlation of adjacent image blocks to search for the same VQ index with the current encoding index from the neighboring indices. To increase compression efficiency, codewords in the codebook are sorted according to the degree of similarity of adjacent VQ indices to generate a state codebook to find the same index with the current encoding index. Note that the repetition indices both on the search path and in the state codebooks are excluded to increase the possibility for matching the current encoding index. Experimental results illustrated the superiority of our scheme over other compression schemes in the index domain.

• The KIPS Transactions:PartD
• /
• v.13D no.3 s.106
• /
• pp.357-368
• /
• 2006

This paper discusses the way of processing time-series subsequence matching under time warping. Time warping enables finding sequences with similar patterns even when they are of different lengths. The prefix-querying method is the first index-based approach that performs time-series subsequence matching under time warping without false dismissals. This method employs the $L_{\infty}$ as a base distance function for allowing users to issue queries conveniently. In this paper, we extend the prefix-querying method for absorbing $L_1$, which is the most-widely used as a base distance function in time-series subsequence matching under time warping, instead of $L_{\infty}$. We also formally prove that the proposed method does not incur any false dismissals in the subsequence matching. To show the superiority of our method, we conduct performance evaluation via a variety of experiments. The results reveal that our method achieves significant performance improvement in orders of magnitude compared with previous methods.

• Journal of the Institute of Electronics Engineers of Korea SP
• /
• v.41 no.5
• /
• pp.45-52
• /
• 2004

According tothe development of digital media technologies various algorithms for video sequence matching have been proposed to match the video sequences efficiently. A large number of video sequence matching methods have focused on frame-wise query, whereas a relatively few algorithms have been presented for video sequence matching or video shot matching. In this paper, we propose an efficientalgorithm to index the video sequences and to retrieve the sequences for video sequence query. To improve the accuracy and performance of video sequence matching, we employ the Cauchy function as a similarity measure between histograms of consecutive frames, which yields a high performance compared with conventional measures. The key frames extracted from segmented video shots can be used not only for video shot clustering but also for video sequence matching or browsing, where the key frame is defined by the frame that is significantly different from the previous fames. Several key frame extraction algorithms have been proposed, in which similar methods used for shot boundary detection were employed with proper similarity measures. In this paper, we propose the efficient algorithm to extract key frames using the cumulative Cauchy function measure and. compare its performance with that of conventional algorithms. Video sequence matching can be performed by evaluating the similarity between data sets of key frames. To improve the matching efficiency with the set of extracted key frames we employ the Cauchy function and the modified Hausdorff distance. Experimental results with several color video sequences show that the proposed method yields the high matching performance and accuracy with a low computational load compared with conventional algorithms.

• Journal of Korea Multimedia Society
• /
• v.2 no.3
• /
• pp.243-251
• /
• 1999

In this paper, we suggest a novel method which defines index for effectively searching MPEG video data. The traditional methods are slow because they rely on pattern matching of images between extracted shots and user's querying images. Whereas, our method uses a different approach: It transforms images of extracted PFrames into codes and uses the codes for creating index keys. To be specific, we define five features of non-context description for transparency about user's querying.

• The Transactions of the Korean Institute of Electrical Engineers A
• /
• v.48 no.7
• /
• pp.872-880
• /
• 1999

This paper presents an algorithm that can calculate the evaluation index of power system from the transfer capability point of view. The algorithm adopts a successive linear programming skill to solve an optimal solution. Two indices which are transfer margin index and economic matching index have been developed. Prior to calculating these indices, Maximum Load supplying Capability(MLSC) and Economic Load Supplying Capability(ELSC) are utilized as basic data. For man-machine interface, graphical user interface has been implemented so that an unified software package PSTCP(Power System Transfer Capability Program) has been developed. KEPCO systems planned up to 2006 year have been tested to show effectiveness and usefulness of the PSTCP for power system planning stages.

• Journal of Communications and Networks
• /
• v.13 no.4
• /
• pp.400-407
• /
• 2011

Various air indexing and data scheduling schemes for wireless broadcast of spatial data have been developed for energy efficient query processing. The existing schemes are not effective when the clients' data access patterns are skewed to some items. It is because the schemes are based on flat broadcast that does not take the popularity of the data items into consideration. In this paper, thus, we propose a data scheduling scheme letting the popular items appear more frequently on the channel, and grid-based distributed index for non-flat broadcast (GDIN) for window query processing. The proposed GDIN allows quick and energy efficient processing of window query, matching the clients' linear channel access pattern and letting the clients access only the queried data items. The simulation results show that the proposed GDIN significantly outperforms the existing schemes in terms of access time, tuning time, and energy efficiency.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1999.05a
• /
• pp.278-281
• /
• 1999

We designed and fabricated a travelingwave CPW(coplanar waveguide) electrode for LiNbO$_3$ optical modulator. To Investigate the variation of microwave refractive index of these electrodes, we prepared the CPW electrode samples as a function of electrode thickness and measured the TDR and S-parameter. From this results, we could know the electrode conditions of index matching to 2.20 for 1150 nm optical wave index for applying LiNbO$_3$ optical modulator. Also we discussed the some properties of CPW electrode for applying LiNbO$_3$ optical modulator.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.56 no.8
• /
• pp.1367-1372
• /
• 2007

The modem large electric power system has made power system analysis much more complex and difficult. For effective analysis of the power system, model reduction and aggregation is required. In this paper, a new relation index to identify the coherency among the generators is presented and also a new aggregation method is presented to aggregate the coherent generators in the large scale power system while matching the power flow. In order to demonstrate the effects of this aggregation method, it is applied to the IEEE 39 bus test power system and to the 2006 summer power system of Korea Electric Power Corporation, and the simulation results are compared with those of the original system.