• Research in Community and Public Health Nursing
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• v.7 no.2
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• pp.400-409
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• 1996

To investigate industrial fatigue and low back pain, the questionaire survey for subjective symptoms of fatigue and low back pain was carried out among 591 male workers aged 20-55 employed in an automobile industry in Korea. Workers participated to this study were divided into low back pain group(LBP) and control group, according to the self-reports by written questionaires. The subjective sysptoms of fatigue comprised three groups of 10 items each, representing dullness and sleepiness(level of cerebral activation), difficulty in concentration(level of motivation) and bodily projection of fatigue. The resultant data were processed for $\chi^2-test$, t-test and a pearson's correlation coefficient to confirm the relationships. The results were as follows: 1. 30 items of fatigue subjective symptoms exeptone item, 'lack in perseverance', were directly associated with low back pain. 2. The percentage of fatigue complaint were sig nificantly higher in LBP group. 3. Of the 30 items of fatigue subjective symptoms, the highest percentage was accounted for 'eye strain'(27.9%), followed by 'whole body feels tired' and 'legs feel heavy'(22.9%), 'feel like lying'(21.4%), 'feel a pain in the low back'(18.7%), 'feel drowsy'(16.4%) and 'feel stiffness in the neck or the shoulders'(16.2%) in the order of sequence. 4. The average weighted score for the first group of fatigue items(dullness and sleepiness) was the largest among three groups and was followed by the second group(difficulty in concentration) and the third group(bodily projection of fatigue) in the order of sequence, suggesting the heavier shift work stress of the workers. 5. In the groups of the aged 30-40, work duration of 5-7yrs, heavy work amount and irregular work speed, significant high fatigue complaints were revealed in terms of eye strain, whole body feels tired, legs feel heavy, feel like lying, feel a pain in the low back and feel stiffness in the neck or the shoulders. 6. A significant negative correlations were shown between age, work duration and eleven subjective symptoms while positive reciprocal correlations were shown between eleven items with one another.

• Nuclear Engineering and Technology
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• v.38 no.4
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• pp.383-390
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• 2006

Having its roots in medical applications, industrial gamma ray CT has opened up new roads far investigating and modeling industrial processes. Using a line of research related to industrial gamma ray CT, the authors set up a system of single source and detector gamma transmission tomography for wood timber and a packed bed phantom. The hardware of the CT system consists of two servo motors, a data logger, a computer, a radiation source and a radiation detector. One motor simultaneously moves the source and the detector for a parallel beam scanning, whereas the other motor rotates the scan table at a preset projection angle. The image is reconstructed from the measured projections by the filtered back projection method. The phantom was designed to simulate a cross section of a packed bed with a void. The radiation source was 20mCi of Cs-137 and the detector was a 1 inch $\times$ 1 inch NaI (TI) scintillator shielded by a lead collimator. The experimental gamma ray CT image has sufficient resolution to reveal air holes and the density distribution inside the phantom. The system could possibly be applied to a packed bed column or a pipe flow in a petrochemical plant.

• Investigative Magnetic Resonance Imaging
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• v.9 no.1
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• pp.36-42
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• 2005

Purpose : To develop a novel approach to calculate the sensitivity profiles of the phased array coil for use in non-uniform intensity correction. Materials and Methods : The proposed intensity correction method estimates the sensitivity profile of the coil to extract intensity variations that represent the scanned image. The sensitivity profile is estimated by fitting a non-linear curve to various angles of projections through the imaged object in order to eliminate the high-frequency image content. Filtered back projection is then used to compute the estimates of the sensitivity profile of each coil. The method was applied both to phantom and brain images from 8-channel phased-array coil and 4-channel phased-array coil, respectively. Results : Intensity-corrected images from the proposed method have more uniform intensity than those from the commonly used 'sum-of-squares' approach. By using the proposed correction method, the intensity variation was reduced to $6.1\%$ from $13.1\%$, acquired from the 'sum-of-squares'. Conclusion : The proposed method is more effective at correcting the intensity non-uniformity of the phased-array surface-coil images than the conventional 'sum-of-squares' method.

• Korean Journal of Occupational Health Nursing
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• v.8 no.2
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• pp.162-168
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• 1999

To investigate industrial fatigue and low back pain, the questionaire survey for subjective symptoms of fatigue and low back pain was carried out 305 nurses in general hospital in Korea. Nurses participated to this study were divided into low back pain group(LBP) and control group, according to the self-reports by written questionaires. The subjective sysptoms of fatigue comprised three groups of 10 items each, representing dullness and sleepiness(level of cerebral activation), difficulty in concentration(level of motivation) and bodily projection of fatigue. The resultant data were processed for $x^2$-test, t-test to confirm the associations. The results were as follows: 1. 28 items of fatigue subjective symptoms exept two item, 'feel thirsty and 'feel ill', were directly associated with low back pain. 2. The percentage of fatigue complaint were significantly higher in LBP group than control. 3. Of the 30 items of fatigue subjective symptoms, the highest percentage was accounted for 'legs feel heavy', 'eye strain', 'feel stiffness in the neck or the shoulders' followed by 'feel like lying', 'whole body feels tired', 'feel a pain in the low back', 'feel drowsy' and in the order of sequence. 4. The average weighted score for the first group of fatigue items(dullness and sleepiness) was the largest among three groups and was followed by the second group(difficulty in concentration) and the third group (bodily projection of fatigue) in the order of sequence, suggesting the heavier mental and shift work stress of the female workers.

• Korean Journal of Optics and Photonics
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• v.11 no.6
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• pp.441-446
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• 2000

Wigner functions and density matrices are computer simulated for various quantum mechanical states of light. Wigner function and density matrices are evaluated by filtered back projection which includes inverse Radon transform from the distribution function of the photocurrents, which are calculated in the balanced homodyne detection scheme. The density matrix is also directly obtained by using the pattern function from the simulated phase independent photocurrent distribution function. ction.

• Journal of Biomedical Engineering Research
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• v.22 no.3
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• pp.223-229
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• 2001

In this paper, we have compared the direct fan-beam reconstruction method with the rebinning method in terms of computation time and spatial resolution using computer simulation. As a result, the direct fan-beam method is superior to the rebinning method in the spatial resolution though the former needs longer computation time. However, if we adopt the quarter-detector-offset technique to improve the spatial resolution, the rebinning method outperforms the direct fan-beam method. The computation times have been evaluated using the fast algorithms optimized to reduce the number of interpolation calculations at the back-projection, and the spatial resolutions have been compared using the computer generated phantoms.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.7
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• pp.1001-1007
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• 2014

This paper proposes a method to reduce operation time using discrete cosine transform and to improve image quality by the DC gain correction. Conventional filtered back projection (FBP) filtering in the frequency domain using Fourier transform, but the filtering process uses complex number operations. To simplify the filtering process, we propose a filtering process using discrete cosine transform. In addition, the image quality of reconstructed images are improved by correcting DC gain of sinograms. To correct the DC gain, we propose to find an optimum DC weight is defined as the ratio of sinogram DC and optimum DC. Experimental results show that the proposed method gets better performance than the conventional method for phantom and clinical CT images.

• Journal of Sensor Science and Technology
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• v.19 no.2
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• pp.118-123
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• 2010

This paper proposes super-resolution reconstruction algorithm for image enhancement. Super-resolution reconstruction algorithms reconstruct a high-resolution image from multi-frame low-resolution images of a scene. Conventional super- resolution reconstruction algorithms are iterative back-projection(IBP), robust super-resolution(RS)method and standard Papoulis-Gerchberg(PG)method. However, traditional methods have some problems such as rotation and ringing. So, this paper proposes modified algorithm to improve the problem. Experimental results show that this proposed algorithm solve the problem. As a result, the proposed method showed an increase in the PSNR for traditional super-resolution reconstruction algorithms.

• Journal of the Korea Institute of Military Science and Technology
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• v.21 no.1
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• pp.17-24
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• 2018

Polar fomat algorithm (PFA) was derived from medical imaging theory, known as back projection, to process synthetic aperture radar(SAR) data. The difference between the operating condition of SAR and back projection assumption makes two distortions. First, the focusing performance of PFA is degraded in proportion to distances from the scene center. Second, the geometric accuracy in SAR images is distorted. Several methods were introduced to mitigate the distortions, but some disadvantages, such as the geometric discontinuity, are arisen when sub-images are combined. This paper proposes the novel method to compensate the geometric distortion with chirp Z-transform (CZT). This method corrects precisely the geometric errors without any problems, because a whole image can be processed all at once.

• Journal of IKEEE
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• v.25 no.1
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• pp.76-82
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• 2021

In this paper, the compressed sensing basic pursuit denoise algorithm adopted to synthetic aperture radar imaging is investigated to improve the object recognition. From the incomplete data sets for image processing, the compressed sensing algorithm had been integrated to recover the data before the conventional back- projection algorithm was involved to obtain the synthetic aperture radar images. This method can lead to the reduction of measurement events while scanning the objects. An ultra-wideband radar scheme using a stripmap synthetic aperture radar algorithm was utilized to detect objects hidden behind the box. The Ultra-Wideband radar system with 3.1~4.8 GHz broadband and UWB antenna were implemented to transmit and receive signal data of two conductive cylinders located inside the paper box. The results confirmed that the images can be reconstructed by using a 30% randomly selected dataset without noticeable distortion compared to the images generated by full data using the conventional back-projection algorithm.