• Journal of Broadcast Engineering
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• v.16 no.2
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• pp.247-257
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• 2011

In this paper, we propose a scene adaptive method to obtain two LDR images with proper shutter speeds which capture the irradiance of scene effectively. The proposed method adaptively selects two shutter speeds across the video frame even when the illumination varies continuously. For the performance evaluation, we compute the PNSR to the ground truth which is obtained by the state-of-the-art HDR imaging method. It shows that the proposed method is able to select approximately optimal shutter speeds while avoiding the exhaustive search of every possible pair of shutter speeds.

• Journal of Astronomy and Space Sciences
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• v.14 no.2
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• pp.251-258
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• 1997

The detection of jovian hydrogen-hydrogen dimers through the clear telluric 2-micron window(Kim et al. 1995, Trafton et al. 1997( suggests possibility to detect noble gases in the form of dimer with hydrogen in jovian atmospheres. Since noble noble gases do not have spectral structures in the infrared, it has been difficult to derive their abundances in the atmospheres of jovian planets. If there is a significant component of noble gases other than helium in the jovian atmospheres. it might be detected through its dimer spectrum with hydrogen molecule. The relatively sharp spectral structures of hydrogen-argon and hydrogen-neon dimers compared with those of hydrogen-hydrogen dimers are useful for the detection, if an adequate signal-to-noise (S/N) is obtained. If we use a large telescope, such as the Keck telescope, with a long exposure time (>24 hours), then $H_2-Ar$ spectral structure may be detected.

• Korean Journal of Materials Research
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• v.16 no.7
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• pp.455-459
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• 2006

Coincidence Doppler Broadening (CDB) of positron annihilation spectroscopy was applied to analyze defects in the chemical state of Department of Physics, $Gd_2O_2S$:Tb intensifying screens. The screen samples were irradiated by 80 MV X-rays in hospital and were used for 0, 2, 4, and 6 years respectively. There was a positive relationship between the S-parameter values and time of exposure to X-rays. Most of the defects were indicated to have been generated by X-rays. A 1D CDB was developed in order to reduce the background noise, and the S-parameter values of the $Gd_2O_2S$:Tb intensifying screens, using the 1D CDB, varied between 0.4974 and 0.4991.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.91-91
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• 2012

We present high-resolution near-infrared host galaxy spectra of low-z quasars, PG0844+349 (z=0.064), PG1226+023 (z=0.158), and PG1426+015 (z=0.086). The observation was done by using the near-IR high resolution echelle spectrometer, IRCS, at the SUBARU 8.2 m telescope. The full width at half maximum of the point spread function was about 0.3 arcsec by using an Adaptive Optics system, which can effectively resolve the quasar spectra from the host galaxy spectra. The signal-to-noise ratios are increased by the total exposure time up to several hours per targets and the development of data reduction method. We compare our results to the stellar spectra library and sample spectra from Dasyra et al. (2007) and Watson et al. (2008). The identified spectral lines will be used to study the physical mechanism of quasars, and the velocity dispersions of the stars in the bulge of the host galaxy.

• Progress in Medical Physics
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• v.31 no.3
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• pp.81-98
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• 2020

This review aims to provide a brief, comprehensive overview of advanced technologies of nuclear medicine physics, with a focus on recent developments from both hardware and software perspectives. Developments in image acquisition/reconstruction, especially the time-of-flight and point spread function, have potential advantages in the image signal-to-noise ratio and spatial resolution. Modern detector materials and devices (including lutetium oxyorthosilicate, cadmium zinc tellurium, and silicon photomultiplier) as well as modern nuclear medicine imaging systems (including positron emission tomography [PET]/computerized tomography [CT], whole-body PET, PET/magnetic resonance [MR], and digital PET) enable not only high-quality digital image acquisition, but also subsequent image processing, including image reconstruction and post-reconstruction methods. Moreover, theranostics in nuclear medicine extend the usefulness of nuclear medicine physics far more than quantitative image-based diagnosis, playing a key role in personalized/precision medicine by raising the importance of internal radiation dosimetry in nuclear medicine. Now that deep-learning-based image processing can be incorporated in nuclear medicine image acquisition/processing, the aforementioned fields of nuclear medicine physics face the new era of Industry 4.0. Ongoing technological developments in nuclear medicine physics are leading to enhanced image quality and decreased radiation exposure as well as quantitative and personalized healthcare.

• Journal of muscle and joint health
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• v.31 no.1
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• pp.53-63
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• 2024

Purpose: This study aimed to determine the prevalence of dizziness in adults and to identify factors associated with dizziness. Methods: This cross-sectional study used secondary data from the Eighth Korea National Health and Nutrition Examination Survey. Participants included 10,265 older adults aged≥40 years. Data were analyzed using descriptive statistics, the chi-squared test, and multinomial logistic regression with the SPSS/WIN 27.0 program. Results: The prevalence of dizziness was 26.2%, with 20.9% reporting episodic dizziness and 5.3% reporting chronic dizziness. Compared to that noted in the control group participants without dizziness, the risk of episodic or chronic dizziness was higher in women and in participants with older age, low education level, low income level, high perceived stress level, depression, tinnitus, and occupational noise exposure. Moreover, the risk of chronic dizziness was higher among those with a body mass index of <25 kg/m², stroke, cardiovascular disease, or severe hearing loss. Conclusion: The study underscores the need to comprehensively identify risk factors associated with dizziness and to develop interventions to prevent and manage the occurrence and chronicity of dizziness in the general population.

• Nuclear Engineering and Technology
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• v.56 no.6
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• pp.2190-2194
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• 2024

The study investigates the dose-dependent direct X-ray sensing characteristics of Brucinium benzilate (BB) and N-acetylglycine (NAG) organic crystals. BB and NAG were prepared as a slurry and deposited as a thick film on a patterned metal electrode. The X-ray induced photocurrent response was examined for various exposure doses using an intraoral pulsed 70 keV X-ray machine connected to a source meter. Subsequently, the morphological properties and thickness of the thick films were analyzed using scanning electron microscopy (SEM). At a photon energy of 70 keV, the attenuation coefficient values for NAG and BB crystals were determined to be approximately 0.181 and 0.178 cm²/g, respectively. The X-ray stopping power of the crystals was measured using a suniray-2 X-ray imaging system. To evaluate the responsiveness of the sensors, the photocurrent sensitivity and noise equivalent dose rate (NED) were calculated for both thick films. The findings demonstrated a noteworthy capability of sensing low doses (mGy), thereby suggesting the potential application of these organic materials in X-ray sensor development.

• 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).

• The Journal of the Korea Contents Association
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• v.10 no.6
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• pp.329-335
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• 2010

Digital imaging detectors can use a variety of detection materials to convert X-ray radiation either to light or directly to electron charge. Many detectors such as amorphous silicon flat panels, CCDs, and CMOS photodiode arrays incorporate a scintillator screen to convert x-ray to light. The digital radiography systems based on semiconductor detectors, commonly referred to as flat panel detectors, are gaining popularity in the clinical & hospital. The X-ray detectors are described between a-Silicon based indirect type and a-Selenium based direct type. The DRS of detectors is used to convert the x-ray to electron hole pairs. Image processing is described by specific image features: Latitude compression, Contrast enhancement, Edge enhancement, Look up table, Noise suppression. The image features are tuned independently. The final enhancement result is a combination of all image features. The parameters are altered by using specific image features in the different several hospitals. The image in a radiological report consists of two image evaluation processes: Clinical image parameters and MTF is a descriptor of the spatial resolution of a digital imaging system. We used the edge test phantom and exposure procedure described in the IEC 61267 to obtain an edge spread function from which the MTF is calculated. We can compare image in the processing parameters to change between original and processed image data. The angle of the edge with respect to the axes of detector was varied in order to determine the MTF as a function of direction. Each MTF is integrated within the spatial resolution interval of 1.35-11.70 cycles/mm at the 50% MTF point. Each image enhancement parameters consists of edge, frequency, contrast, LUT, noise, sensitometry curve, threshold level, windows. The digital device is also shown to have good uniformity of MTF and image parameters across its modality. The measurements reported here represent a comprehensive evaluation of digital radiography system designed for use in the DRS. The results indicate that the parameter enables very good image quality in the digital radiography. Of course, the quality of image from a parameter is determined by other digital devices in addition to the proper clinical image.

• The Journal of the Acoustical Society of Korea
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• v.35 no.1
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• pp.24-34
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• 2016

The popularity of personal listening devices(PLDs) has increased over past years, especially, in adolescents. Overuses and missuses of PLDs could be the cause of noise-induced hearing loss (NIHL). The purposes of this study were (1) to survey middle school students' habits using PLDs, knowledge of hearing loss and attitude of hearing protection and (2) to develope a questionnaire for assessment of habits using PLDs, knowledge of hearing loss and attitude of hearing protection in adolescents. The 41-item questionnaire was designed and used to survey middle school students' habits using PLDs, knowledge of hearing loss and attitude of hearing protection. A total of 404 middle school students aged 14-15 years participated in the survey. Most of the students were found to use PLDs soundly. However, 30 % of students used PLDs for more than 3 hours a day. Also, almost all of the students did not understand knowledge of the causes of hearing loss, but showed interests in hearing protection. However, some students had insufficient understanding of the causes of hearing loss and the needs of hearing protection. The results suggest that the development of programs for adolescents' hearing health is needed.