• ETRI Journal
• /
• v.28 no.4
• /
• pp.506-508
• /
• 2006

A frequency selective surface (FSS), whose unit cell consists of a ternary tree loop loaded with a modified tripole, is proposed to block multiple frequency bands. Target frequency bands correspond to Korean personal communication services, cellular mobile communication, and 2.4 GHz industrial, scientific, and medical bands. Through the adjustment of inter-element and inter-unit cell gaps, and adjustment of the length of elements, we present an FSS design method that makes the precise tuning of multiple resonance frequencies possible. Additionally, to verify the validity of our approach, simulation results obtained from a commercial software tool and experimental data are also presented.

• 제어로봇시스템학회:학술대회논문집
• /
• 1987.10b
• /
• pp.597-602
• /
• 1987

This paper proposes a voltage-fed high frequency resonant inverter having variable voltage variable frequency(VVVF) control function. VVVF control is performed by PWM-TRC method in the boost type chopper and PFM-TRC method in the high frequency resonant inverter. This circuit is suitable for induction heating and melting power supply in industry. The operating characteristics of this inverter are discussed from a theoretical point of view. The results of operating characteristic analyses are given leading to complete designing data.

• Proceedings of the IEEK Conference
• /
• 2006.06a
• /
• pp.101-102
• /
• 2006

Similar to Orthogonal Frequency Division Multiplexing (OFDM), a Single Carrier with Frequency Domain Equalization (SC-FDE) system is computationally efficient since equalization is performed on a block of data in the frequency domain. In coherent QAM schemes, the mean phase rotation error caused by the residual carrier frequency offset may lead to serious degradation. When the frequency equalizer is combined with the mean phase error tracking algorithm, its performance can be enhanced noticeably.

• Journal of Korea Multimedia Society
• /
• v.15 no.4
• /
• pp.526-539
• /
• 2012

This paper proposes a high capacity data hiding method using high frequence secret data indexing algorithm. Many novel data hiding methods based on LSB and PVD methods were presented to enlarge hiding capacity and provide an imperceptible quality. In this paper, first, calculating data iteration frequency of the secret message and make up the high frequency data index matrix (HFDT) using high frequence data's location information. Next, HFDT uses to that data hiding process on the cover image and recovering process on the stego image. The experimental results demonstrate the efficiency of the proposed high frequency secret data indexing method. For the data hiding method, experiments are conducted for four cases: 2 pattern secret data (2PD), 4 pattern secret data (4PD), 8 pattern secret data (8PD) and higher pattern secret data (HPD). When comparing the proposed method with other data hiding methods, for the HPD case, the results show that the proposed method has a good PSNR and more capacity, and for the other case, the results show that the proposed method has a higher PSNR and larger capacity.

• Proceedings of the IEEK Conference
• /
• 2001.06c
• /
• pp.77-80
• /
• 2001

In general, the informations of the inner image that user interested in are limited to a special domain. In this paper, as using Wavelet Transform for dividing image into high frequency and low frequency, We can separate foreground including many data. After calculating object boundary of separated part, We extract special features using Color Coherence Vector. According to results of this experiment, the method of comparing data extracting foreground features is more effective than comparing data extracting features of entire image when we extract the image user interested in.

• Proceedings of the IEEK Conference
• /
• 2000.06c
• /
• pp.125-128
• /
• 2000

In this paper, we proposed the high quality digital audio watermarking algorithm in the frequency domain. The spread spectrum technique is used to encrypted a stream of information by spreading the data as much of the frequency spectrum as possible. It's technique adapt well to data hiding in audio signal. We have used the perceptual model and MDCT/IMDCT for the high qualify digital audio watermarking. The proposed watermark algorithm preserved high quality audio data from watermark signal.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
• /
• 2003.04a
• /
• pp.105-109
• /
• 2003

The occurrence of cycle slips is a major limiting factor to attain high precision positioning and navigation results with GPS. Cycle slips must be correctly repaired at the data processing stage. In this study, the technique to find cycle slips in the processing of data collected with Trimble 4700 GPS receivers is suggested. The use of Kalman filtering techniques is used in an attempt to reduce the effect of the noise in the different quantities involved and to improve the accuracy in cycle slip correction.

• Journal of the Korean Data and Information Science Society
• /
• v.15 no.1
• /
• pp.219-226
• /
• 2004

In this paper, we consider two-components system which the lifetimes have a bivariate Weibull distribution with bivariate random censored data. Here the bivariate censoring times are independent of the lifetimes of the components. We obtain estimators and approximated confidence intervals for the reliability of series system based on likelihood function and relative frequency, respectively. Also we present a numerical study.

• Journal of the Optical Society of Korea
• /
• v.20 no.2
• /
• pp.276-282
• /
• 2016

A 2 Gbit/s visible-light communication (VLC) scheme using time-frequency color-clustered (TFCC) multiple-input multiple-output (MIMO) based on blue, cyan, yellow, and red (BCYR) light-emitting diodes (LEDs) is presented. In the proposed scheme, BCYR LEDs are employed to form four different color clusters. Data transmission using the four color clusters is performed in MIMO, so that the scheme achieves a very high speed of data transmission. Moreover, the scheme employs the TFCC strategy to yield high performance in terms of bit error rate (BER). TFCC operates in such a way that the original data and the two delayed versions of the data are multiplied by orthogonal frequencies and then transmitted using a specific color of the BCYR LED. In the receiver, color filters are employed to detect the data transmitted from the desired cluster. Selection combining (SC) is also performed to yield a diversity effect within each color cluster, to further improve the performance. Performance evaluation demonstrates that the proposed TFCC MIMO VLC offers a data rate of 2 Gbit/s and a bit error rate of 4×10^-5, at an E_b/N_o value of merely 3 dB.

• Journal of Information Technology and Architecture
• /
• v.10 no.3
• /
• pp.387-397
• /
• 2013

This paper proposes an approach to big data analytics for phon call data. The analytical models for phon call data is composed of the PVPF (Parallel Variable-length Phrase Finding) algorithm for identifying verbal phrases of natural language and the word count algorithm for measuring the usage frequency of keywords. In the proposed model, we identify words using the PVPF algorithm, and measure the usage frequency of the identified words using word count algorithm in MapReduce. The results can be interpreted from various viewpoints. We design and implement the model based HDFS (Hadoop Distributed File System), verify the proposed approach through a case study of phon call data. So we extract useful results through analysis of keyword correlation and usage frequency.