• Journal of the Korean Society of Radiology
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• v.17 no.3
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• pp.367-373
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• 2023

Aircrews and passengers are exposed to radiation from cosmic rays and secondary scattered rays generated by reactions with air or aircraft. For aircrews, radiation safety management is based on the exposure dose calculated using a space-weather environment simulation. However, the exposure dose varies depending on solar activity, altitude, flight path, etc., so measuring by route is more suggestive than the calculation. In this study, we developed an instrument to measure the cosmic radiation dose using a general-purpose Si sensor and a multichannel analyzer. The dose calculation applied the algorithm of CRaTER (Cosmic Ray Telescope for the Effects of Radiation), a space radiation measuring device of NASA. Energy and dose calibration was performed with Cs-137 662 keV gamma rays at a standard calibration facility, and good dose rate dependence was confirmed in the experimental range. Using the instrument, the dose was directly measured on the international line between Dubai and Incheon in May 2023, and it was similar to the result calculated by KREAM (Korean Radiation Exposure Assessment Model for Aviation Route Dose) within 12%. It was confirmed that the dose increased as the altitude and latitude increased, consistent with the calculation results by KREAM. Some limitations require more verification experiments. However, we confirmed it has sufficient utilization potential as a cost-effective measuring instrument for monitoring exposure dose inside or on personal aircraft.

• Information Systems Review
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• v.25 no.1
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• pp.213-231
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• 2023

With the rapid development of live streaming commerce, online host as an information source plays a critical role in affecting live streaming performance. However, the impact of different product types on the relationship between online hosts and live streaming has been less studied. Based on the elaboration likelihood model (ELM) and information source theory, this study aims to empirically investigate what factors influence the sales of live streaming commerce and how product type moderates the relationship between them. The analysis of 11,422 live streaming commerce data collected for four months from October 10, 2021 to February 10, 2022 shows that, among the factors related to source credibility and attractiveness, multi-channel networks (MCN) and the number of followers positively affect the sales volume of live streaming commerce, whereas the reputation score harms the sales. Moreover, the moderating effect of the product type (i.e., ratio of involvement products) on the relationships is confirmed. The findings enrich the literature on live streaming commerce performance. The limitations and future research directions are also discussed.

• Journal of radiological science and technology
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• v.31 no.1
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• pp.71-81
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• 2008

Our objective was to evaluate the image of spatial domain filtering as an alternative to additional image reconstruction using different kernels in MDCT. Derived from thin collimated source images were generated using water phantom and abdomen B10(very smooth), B20(smooth), B30(medium smooth), B40 (medium), B50(medium sharp), B60(sharp), B70(very sharp) and B80(ultra sharp) kernels. MTF and spatial resolution measured with various convolution kernels. Quantitative CT attenuation coefficient and noise measurements provided comparable HU(Hounsfield) units in this respect. CT attenuation coefficient(mean HU) values in the water were values in the water were $1.1{\sim}1.8\;HU$, air($-998{\sim}-1000\;HU$) and noise in the water($5.4{\sim}44.8\;HU$), air($3.6{\sim}31.4\;HU$). In the abdominal fat a CT attenuation coefficient($-2.2{\sim}0.8\;HU$) and noise($10.1{\sim}82.4\;HU$) was measured. In the abdominal was CT attenuation coefficient($53.3{\sim}54.3\;HU$) and noise($10.4{\sim}70.7\;HU$) in the muscle and in the liver parenchyma of CT attenuation coefficient($60.4{\sim}62.2\;HU$) and noise ($7.6{\sim}63.8\;HU$) in the liver parenchyma. Image reconstructed with a convolution kernel led to an increase in noise, whereas the results for CT attenuation coefficient were comparable. Image scanned with a high convolution kernel(B80) led to an increase in noise, whereas the results for CT attenuation coefficient were comparable. Image medications of image sharpness and noise eliminate the need for reconstruction using different kernels in the future. Adjusting CT various kernels, which should be adjusted to take into account the kernels of the CT undergoing the examination, may control CT images increase the diagnostic accuracy.

• Journal of the korean academy of Pediatric Dentistry
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• v.47 no.4
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• pp.446-453
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• 2020

The purpose of this study was to evaluate the effect of Indocyanine Green (ICG) and near-infrared (NIR) diode laser on Streptococcus mutans biofilms depending on ICG concentrations. S. mutans biofilms were formed on a Hydroxyapatite disk, and 0.5, 1.0, 2.0, 3.0, 4.0, 5.0 mg/mL ICG solutions dissolved in sterile distilled water and a NIR diode laser having a power of 300 mW and a wavelength of 808 nm were applied to the biofilms. The temperature changes of the biofilm surface according to the concentrations of the ICG solution were measured using a 1-channel thermocouple thermometer. Compared to the control group, in the groups with only the 3.0, 4.0, 5.0 mg/mL ICG solution application, and in the groups with the 1.0, 2.0, 3.0, 4.0, 5.0 mg/mL ICG solution application and light irradiation, a statistically significant decrease in the bacterial counts were observed. The temperature increase according to the concentration of the ICG solutions was 9.53℃, 10.43℃, 11.40℃, 12.10℃, 12.67℃, and 13.63℃ in ICG solutions of 0.5, 1.0, 2.0, 3.0, 4.0, and 5.0 mg/mL respectively. This study presents the potential for clinical application of ICG and NIR diode lasers as a new method for preventing dental caries.

• Korean Journal of Remote Sensing
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• v.32 no.6
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• pp.733-739
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• 2016

Insolation is an major indicator variable that can serve as an energy source in earth system. It is important to monitor insolation content using remote sensing to evaluate the potential of solar energy. In this study, we performed sensitivity analysis of observed frequency on daily composite insolation over the Korean peninsula. We estimated INS through the channel data of Communication, Ocean and Meteorological Satellite (COMS) and Cloud Mask which have temporal resolution of 1 and 3 hours. We performed Hemispherical Integration by spatial resolution for meaning whole sky. And we performed daily composite insolation. And then we compared the accuracy of estimated COMS insolation data with pyranometer data from 37 points. As a result, there was no great sensitivity in the daily composite INS by observed frequency of satellite that accuracy of the calculated insolation at 1 hour interval was $28.6401W/m^2$ and 3 hours interval was $30.4960W/m^2$. However, there was a great difference in the space distribution of two other INS data by observed frequency of clouds. So, we performed sensitivity analysis with observed frequency of clouds and distinction between the two other INS data. Consequently, there was showed sensitivity up to $19.4392W/m^2$.

• Geophysics and Geophysical Exploration
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• v.16 no.4
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• pp.240-249
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• 2013

The seismic data quality of marine geological and engineering survey deteriorates because of the sea swell. We often conduct a marine survey when the swell height is about 1 ~ 2 m. The swell effect correction is required to enhance the horizontal continuity of seismic data and satisfy the resolution less than 1 m. We applied the swell correction to the 8 channel high-resolution airgun seismic data and 3.5 kHz subbottom profiler (SBP) data. The correct sea bottom detection is important for the swell correction. To detect the sea bottom, we used maximum amplitude of seismic signal around the expected sea bottom, and picked the first increasing point larger than threshold value related with the maximum amplitude. To find sea bottom easily in the case of the low quality data, we transformed the input data to envelope data or the cross-correlated data using the sea bottom wavelet. We averaged the picked sea bottom depths and calculated the correction values. The maximum correction of the airgun data was about 0.8 m and the maximum correction of two kinds of 3.5 kHz SBP data was 0.5 m and 2.0 m respectively. We enhanced the continuity of the subsurface layer and produced the high quality seismic section using the proper methods of swell correction.

• Journal of Chest Surgery
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• v.32 no.6
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• pp.579-583
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• 1999

Background: Thoracic sympathicotomy has been used safely and successfully to manage palmar hyperhidrosis. The preoperative and postoperative recording of Sympathetic Skin Responses(SSR) was performed for objective evaluation and follow-up of thoracic sympathicotomy in hyperhidrosis patients, and also for ascertaining the clinical usefullness of SSR. Material and Method: The recording of SSR was performed on 15 patients suffering from palmar hyperhidrosis with Medelec Sapphire Plus electromyogragh before and after thoracic sympathicotomy. Eletrical stimuli on the right median nerve was made in patients in supine position and results were recorded on right and left palms with soles at the same time by 4 channels. Skin temperatures were also monitored simultaneously. T2,3 sympathicotomy was performed with VATS in every patients. SSR was done in 2 patients one month later. Result: Clinically, all patients had symptomatic improvement with satisfaction. Postoperative complication was small amount of residual pneumothorax in 5 patients but it was absorbed sponteneously. There was no recurrence during follow-up period and ten patients(66%) complained compensatory hyperhidrosis. After operation, SSR change was shown in every 15 patients. Abolition of SSR on both palms was achieved in 12 patients(80%) and on both soles in 6 patients. In the other 3 patients, the latencies were significantly delayed and the amplitudes were significantly reduced at both palms and soles. In two patients who were examined at one month later after operation, similar results with postoperative SSRs were shown. The skin temperature on preoperative both palm and sole were lower than normal temperature, and those on postoperative both palm and sole were increased. Those had statistical significance(p<0.05), and the temperature on the palm was increased higher that than on the sole. Conclusion: After thoracic sympathicotomy was performed on palmar hyperhidrosis patients, an increment of skin temperatures and SSR changes were achieved at both palms and soles of all patients. Palmar SSRs were completely abolished in 12 patients(80%), and similar results of postoperative SSRs were achieved. The recording of SSR may be useful to easily and objectively assess the completeness of sympathicotomy and the follow-up of recurrence in hyperhidrosis patients.

• Journal of the Korean earth science society
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• v.39 no.3
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• pp.241-249
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• 2018

As the international trade increases, vessel traffics around the Korean Peninsula are also increasing. Maritime accidents hence take place more frequently in the southern coast of Korea where many big and small ports are located. Accidents involving ship collision and sinking result in a substantial human and material damage as well as the marine environmental pollution. Therefore, it is necessary to locate the ships quickly when such accidents occur. In this study, we suggest a new ship detection index by comparing and analyzing the reflectivity of each channel of the Korea MultiPurpose SATellite-2 (KOMPSAT-2) images of the area around the Gwangyang Bay. A threshold value of 0.1 is set based on a histogram analysis, and all vessels are detected when compared with RGB composite images. After selecting a relatively large ship as a representative sample, the distribution of spatial reflectivity around the ship is studied. Uniform shadows are detected on the northwest side of the vessel. This indicates that the sun is in the southeast, the azimuth of the actual satellite image is $144.80^{\circ}$, and the azimuth angle of the sun can be estimated using the shadow position. The reflectivity of the shadows is 0.005 lower than the surrounding sea and ship. The shadow height varies with the position of the bow and the stern, perhaps due to the relative heights of the ship deck and the structure. The results of this study can help search technology for missing vessels using optical satellite images in the event of a marine accident around the Korean Peninsula.

• Science of Emotion and Sensibility
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• v.6 no.4
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• pp.9-14
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• 2003

Sleep stages have been useful indicator to check a person's comfortableness in a sleep, But the traditional method of scoring sleep stages with polysomnography based on the integrated analysis of the electroencephalogram(EEG), electrooculogram(EOG), electrocardiogram(ECG), and electromyogram(EMG) is too restrictive to take a comfortable sleep for the participants, While the sympathetic nervous system is predominant during a wakefulness, the parasympathetic nervous system is more active during a sleep, Cardiovascular function is controlled by this autonomic nervous system, So, we have interpreted the heart rate variability(HRV) among sleep stages to find a simple method of classifying sleep stages, Six healthy male college students participated, and 12 night sleeps were recorded in this research, Sleep stages based on the "Standard scoring system for sleep stage" were automatically classified with polysomnograph by measuring EEG, EOG, ECG, and EMG(chin and leg) for the six participants during sleeping, To extract only the ECG signals from the polysomnograph and to interpret the HRV, a Sleep Data Acquisition/Analysis System was devised in this research, The power spectrum of HRV was divided into three ranges; low frequency(LF), medium frequency(MF), and high frequency(HF), It showed that, the LF/HF ratio of the Stage W(Wakefulness) was 325% higher than that of the Stage 2(p＜.05), 628% higher than that of the Stage 3(p＜.001), and 800% higher than that of the Stage 4(p＜.001), Moreover, this ratio of the Stage 4 was 427% lower than that of the Stage REM (rapid eye movement) (p＜.05) and 418% lower than that of the Stage l(p＜.05), respectively, It was observed that the LF/HF ratio decreased monotonously as the sleep stage changes from the Stage W, Stage REM, Stage 1, Stage 2, Stage 3, to Stage 4, While the difference of the MF/(LF+HF) ratio among sleep Stages was not significant, it was higher in the Stage REM and Stage 3 than that of in the other sleep stages in view of descriptive statistic analysis for the sample group.

• The Korean Journal of Nuclear Medicine
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• v.33 no.1
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• pp.100-109
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• 1999

Purpose: Preamplifier and amplifier are very important parts for developing a portable counting or imaging gamma probe. They can be used for analyzing pulses containing energy and position information for the emitted radiations. The commercial Nuclear Instrument Modules (NIMs) can be used for processing these pulses. However, it may be improper to use NIMs in developing a portable gamma probe, because of its size and high price. The purpose of this study was to develop both preamplifier and amplifier and measure their performance characteristics. Materials and Methods: The preamplifier and amplifier were designed as a charge sensitive device and a capacitor resistor-resistor capacitor (CR-RC) electronic circuit, respectively, and they were mounted on a print circuit board (PCB). We acquired and analyzed energy spectra for Tc-99m and Cs-137 using both PCB and NIMs. Multichannel analyzer (Accuspec/A, Canberra Industries Inc., Meriden Connecticut, U.S.A) and scintillation detectors (EP-047(Bicron Saint-Gobain/Norton Industrial EP-047 (Ceramics Co., Ohio, U.S.A) with $2"{\times}2"$ NaI(T1) crystal and R1535 (Hamamatsu Photonics K.K., Electron Tube Center, Shizuoka-ken, Japan) with $1"{\times}1"$ NaI(T1) crystal were used for acquiring the energy spectra. Results: Using PCB, energy resolutions of EP-047 detectors for Tc-99m and Cs-137 were 12.92% and 5.01%, respectively, whereas R1535 showed 13.75% and 5.19% of energy resolution. Using the NIM devices, energy resolutions of EP-047 detector for Tc-99m and Cs-137 were measured as 14.6% and 7.58%, respectively. However, reliable energy spectrum of R1535 detector could not be acquired, since its photomultiplier tube (PMT) requires a specific type of preamplifier. Conclusion: We developed a special preamplifier and amplifier suitable for a small sized gamma probe that showed good energy resolutions independent of PMT types. The results indicate that the PCB can be used in developing both counting and imaging gamma probe.