• Journal of information and communication convergence engineering
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• v.7 no.3
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• pp.404-411
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• 2009

In this paper, in order to increase system capacity and reduce the transmitting power of the user's equipment, we propose an efficient power estimation consisting of a modified open-loop power control (OLPC) and closed-loop power control (CLPC) schemes for mobile/satellite communications systems. The OLPC works well if the forward and reverse links are perfectly correlated and the CLPC is sensitive to round-trip delay (RTD). Therefore, it is not effective in mobile/satellite system. In order to solve the above problem, we added monitoring equipment to both the OLPC and CLPC to use information about transmitting power that has not yet been received by the receiver over the satellite/ATC channel. Moreover, we adapted an efficient pilot diversity of both OLPC and CLPC in order to get a better signal to interference plus noise ratio (SIR) estimation of the received signal.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.2
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• pp.347-354
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• 2011

This paper presents a time-domain based asynchronous IR-UWB ranging system. This system accomplishes the ranging by detecting peaks from the outputs of a correlator implemented by a FIR filter. To discriminate the peaks due to a signal component, we use windowing for the correlated data within which the data are sorted in amplitude-ascending order and the noise level is calculated. Comparing with the recently presented frequency-domain based ranging system, we show the system structure and explain how it operates for ranging. Moreover, through the simulations, the proposed system is compared with the frequency-domain based system in terms of performance.

• Korean Journal of Remote Sensing
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• v.24 no.5
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• pp.445-452
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• 2008

Preliminary results are reported on ship detection using coherence images computed from cross-correlating images of multi-look-processed dual-polarization data (HH and HV) of ENVISAT ASAR. The traditional techniques of ship detection by radars such as CFAR (Constant False Alarm Rate) rely on the amplitude data, and therefore the detection tends to become difficult when the amplitudes of ships images are at similar level as the mean amplitude of surrounding sea clutter. The proposed method utilizes the property that the multi-look images of ships are correlated with each other. Because the inter-look images of sea surface are covered by uncorrelated speckle, cross-correlation of multi-look images yields the different degrees of coherence between the images and water. In this paper, the polarimetric information of ships, land and intertidal zone are first compared based on the cross-correlation between HH and HV images, In the next step, we examine the technique when the dual-polarization data are split into two multi-look images, It was shown that the inter-look cross-correlation method could be applicable in the performance improvement of small ship detection and the land masking, It was also found that a simple combination of coherence images from each co-polarised (HH) inter-look and cross-polarised (HV) inter-look data can provide much higher target-detection possibilities.

• Smart Structures and Systems
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• v.31 no.5
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• pp.501-516
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• 2023

Dynamic irregularity and acceleration of bridges subjected to high-speed trains provide crucial information for comprehensive evaluation of the health state of under-track structures. This paper proposes a novel approach for real-time estimation of vertical track dynamic irregularity and bridge acceleration using deep generative adversarial network (GAN) and vibration data from in-service train. The vehicle-body and bogie acceleration responses are correlated with the two target variables by modeling train-bridge interaction (TBI) through least squares generative adversarial network (LSGAN). To realize supervised learning required in the present task, the conventional LSGAN is modified by implementing new loss function and linear activation function. The proposed approach can offer pointwise and accurate estimates of track dynamic irregularity and bridge acceleration, allowing frequent inspection of high-speed railway (HSR) bridges in an economical way. Thanks to its applicability in scenarios of high noise level and critical resonance condition, the proposed approach has a promising prospect in engineering applications.

• The Journal of the Acoustical Society of Korea
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• v.27 no.8
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• pp.443-449
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• 2008

One of the key issues in practical speech processing is to achieve robust Voice Activity Deteciton (VAD) against the background noise. Most of the statistical model-based approaches have tried to employ equally weighted likelihood ratios (LRs), which, however, deviates from the real observation. Furthermore voice activities in the adjacent frames have strong correlation. In other words, the current frame is highly correlated with previous frame. In this paper, we propose the effective VAD approach based on a minimum classification error (MCE) method which is different from the previous works in that different weights are assigned to both the likelihood ratio on the current frame and the decision statistics of the previous frame.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.25 no.3
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• pp.405-417
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• 2015

Objectives: The aim of this study is to evaluate the association between physical factors, working conditions and occupational injuries among Korean workers. Methods: We used data from the 2nd Korean Working Conditions Survey, conducted in 2010. A total of 7,114 workers over 15 years of age were selected from among 10,019 Korean workers. The participants were interviewed using questionnaires. A multiple logistic regression model was used to analyze the associations among physical factors, working conditions and occupational injuries. Results: After the adjustment of socio-demographic factors, the odds ratio of injuries through physical factors such as vibration (adjusted Odds Ratio [aOR] 4.037, 95% CI 2.30-7.09), noise (aOR 4.562, 95% CI 2.64-7.89), high temperature (aOR 3.262, 95% CI 1.86-5.73), and low temperature (aOR 3.358, 95% CI 1.76-6.41) were greater in the exposed group than in the non-exposed group. The odds ratios of occupational injury(aOR 5.272, 95% CI 3.19-8.7 for very high speed work, aOR 3.303, 95% CI 1.95-5.60 for tight deadlines, and aOR 3.641, 95% CI 1.72-7.70 for not enough time to work) increased with increased work demands. Conclusions: In this study, physical factors such as vibration, noise, and high and low temperatures were significantly correlated with occupational injuries according to the increase in exposure intensity(p for trend <0.001). Also, working conditions such as high-speed work, tight deadlines and insufficient time to work showed significant associations with occupational injuries(p for trend<0.001).

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.3
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• pp.221-229
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• 2013

In this paper, the image formation by the motion compensation technique for Synthetic Aperture Radar system(SAR) were realized through the computer simulation. The motion compensation technique performed image data with the range compression, the compensation procedure, the azimuth compensation and the noise elimination procedure. The range compression procedure transform the SAR raw data into the frequency domain and correlate with the range reference function and then inversely transform into the time domain. The compensation procedure contain the aircraft fluctuations compensation and the radar image degrading effect elimination procedure which was caused by image formation algorithm itself. The aircraft fluctuations compensation procedure perform the first stage which correct the phase angle and the second stage which calculate the Doppler frequency and determine the coordinate of the received signal. The radar image degrading effect elimination procedure also perform range migration compensation and the image defocussing effect compensation. The azimuth compression procedure transform the compensation data to the frequency domain and correlate with the azimuth reference function. The azimuth correlated data are inversely transformed to the time domain which is called SAR image data. When the above procedure were completed, the image data contains the received signals mixed with noise. The threshold technique was applied to elimination the noise from the mixed image data.

• The Journal of Korean Physical Therapy
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• v.14 no.4
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• pp.183-203
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• 2002

To know the effect of index of social ability (ISA) and function of social life (FSL) with activities of daily living (ADL) and instrumental activities of daily living (IADL), we carried out a study on the elderly with osteoarthritis daily living in Daegu city for 4 months, from April to July 2002. The followings were observed: 1. The score of functional disability of knee, ADL and ISA were better at lower age (p < 0.01). 2. The younger they are, the better FSL they have. The lower age group has good FSL (p < 0.01). 3. Weight affects more to the under 49Kg group than 50-59Kg group and 60-69Kg group in functional disability of knee, while it doesn't make much difference for the other groups (p > 0.05) and other assessment index doesn't show any relationship with weight. 4. Regarding relat ionship with height , taller group has better knee functions: it's proved by post hock examination that the over 160cm group has much higher knee function than the other groups (p < 0.05). In case of ADL, the over 160cm group and under 149cm group were better than 150$\∼$159cm group. (p < 0.01) . 5. ISA was also different depending on height . It was proved that FSL was the better for the over 160cm group than for the others as a result of post hock examination (p < 0.05). 6. In regard of how many months have passed since the attack of functional disability of knee, knee joint function was better for the 12mon$\∼$36mon group than for the others and the score of ADL was lower for the 12mon$\∼$36mon group than for the others (p < 0.01). ISA was lower for the 12mon$\∼$36mon group and the under 6mon group than for the other groups (p < 0.01). FSL was lower for the 12mon$\∼$36mon group and the under 6mon group than the other groups. (p < 0.01). 7. Comparing left knee with right one, the problem with left knee has lower score of functional disability in all items (p < 0.01). 8. Considering friction noise, knee joint function was slightly better for non-friction noise-group, but it's not statistically significant though. ADL and ISA were better for non-friction noise-group (p < 0.01), while no statistical significance was found in FSL, 9. Knee joint function was better for the group who doesn't have limitation on range of knee flexion motion (p,0.05) but no other difference was found in other items from this group. 10. Limitation on range of knee flexion motion has no statistical difference in ADL and FSL. However, ISA was better for the non-limitation group (p < 0.05) . 11. Knee joint function score has high correlation with ISA (r=0.812, p < 0.01) and FSL (r=0.732, p < 0.01) , which shows the better knee joint function, the higher the score. 12. ISA and FSL were highly correlated: the better ISA, the better FSL (r=0.893, p < 0.01), while ADL has no correlation with either knee joint function or ISA or FSL.

• Journal of Broadcast Engineering
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• v.15 no.1
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• pp.52-62
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• 2010

Recently, DVC (Distributed Video Coding) is attracting a lot of research works since this enables us to implement a light-weight video encoder by distributing the high complex tasks such as motion estimation into the decoder side. In order to improve the coding efficiency of the DVC, the existing works have been focused on the efficient generation of side information (SI) or the virtual channel modeling which can describe the statistical channel noise well. But, in order to improve the overall performance, this paper proposes a new scheme that can be implemented with simple bit operations without introducing complex operation. That is, the performance of the proposed scheme is enhanced by using the fact that the Wyner-Ziv (WZ) frame and side information are highly correlated, and by reducing the effect of virtual channel noise which tends to be clustered in some regions. For this aim, this paper proposes an efficient pixel-domain WZ (PDWZ) CODEC which effectively exploits the statistical redundancy by using the code conversion and Gray code, and then reduces the channel noise by using the bit interleaver. Through computer simulations, it is shown that the proposed scheme can improve the performance up to 0.5 dB in objective visual quality.

• The Journal of the Acoustical Society of Korea
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• v.32 no.6
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• pp.548-555
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• 2013

The localization of sources has a numerous number of applications. To estimate the position of sources, the relative delay between two or more received signals for the direct signal must be determined. Although the generalized cross-correlation method is the most popular technique, an approach based on eigenvalue decomposition (EVD) is also popular one, which utilizes an eigenvector of the minimum eigenvalue. The performance of the eigenvalue decomposition (EVD) based method degrades in the low SNR and the correlated environments, because it is difficult to select a single eigenvector for the minimum eigenvalue. In this paper, we propose a new adaptive algorithm based on Canonical Correlation Analysis (CCA) in order to extend the operation range to the lower SNR and the correlation environments. The proposed algorithm uses the eigenvector corresponding to the maximum eigenvalue in the generalized eigenvalue decomposition (GEVD). The estimated eigenvector contains all the information that we need for time delay estimation. We have performed simulations with uncorrelated and correlated noise for several SNRs, showing that the CCA based algorithm can estimate the time delays more accurately than the adaptive EVD algorithm.