• Explosives and Blasting
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• v.42 no.3
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• pp.23-37
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• 2024

Recently, earthquakes occurring in Korea have frequently caused damage to buildings and structures. However, since it is impossible to predict when an earthquake will occur, it is challenging to determine the characteristics of the vibrations without pre-installed automated measuring devices. Fortunately, automated measuring devices have been installed at six blasting sites, allowing for the comparison of the characteristics of seismic and blasting vibrations. On June 12, 2024 (Wednesday) at 8:26 AM, a magnitude 4.8 earthquake occurred 4 km south-southwest of Buan-gun, Jeollabuk-do. This study compares the characteristics of seismic vibrations from this earthquake with the measured values of seismic and blasting vibrations at domestic blasting sites. Additionally, we examined the causes and scales of damage from the earthquake, and analyzed the characteristic values obtained from automated measuring devices installed in various regions from the epicenter to determine the degree of attenuation. This study aims to provide a basis for comparing the impact of vibrations from blasting on protected objects and to help preemptively address complaints that may arise from such vibrations in the future.

• Journal of the Society of Disaster Information
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• v.20 no.3
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• pp.549-562
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• 2024

Purpose: In this study, numerical analysis was conducted to verify the vibration reduction effect of installing vibration barriers under various installation conditions to mitigate train-induced vibrations from the GTX. Method: To identify the factors influencing vibration reduction among the installation conditions, the stiffness ratio of the filling material and the installation depth of the barrier were varied. Result: The study results indicated that using ductile filling materials provided superior vibration reduction compared to hard filling materials. The vibration reduction effect was found to be more significant when the stiffness ratio between the ground and the filling material was closer to zero. Additionally, the deeper the installation depth of the barrier, the better the vibration reduction effect. Conversely, if the barrier was installed too shallowly, vibration at the measurement point was amplified. Conclusion: The optimal installation condition for vibration reduction was found to be a stiffness ratio of 0.08 and an installation depth of 15 meters, resulting in a vibration reduction rate of 60.34% at a measurement point 10 meters away from the vibration source.

• Science of Emotion and Sensibility
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• v.18 no.1
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• pp.59-66
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• 2015

To date, contents' usability of most multimedia devices has been focused on developer not on user, which made difficult in solving the problems or fulfilling the needs while people using real system. Although user-centered UX and UI researches have been studied and have resulted in innovation in some part, it does not show great effect on usability as it is not easy to interpret human emotions and needs and to apply those to system. Usability is the matter on how deeply smart devices can interpret and analyze human mind not on how much functions and technologies are improved. This study aims to help with usability improvement based on user when people use smart devices in multimedia environment. We studied the interaction between human and contents by analyzing the effect of human emotions and personalities on preference and consumption of contents' type. This study was done by assuming that proper analysis on human emotions may increase user satisfaction on multimedia environment. We analyzed contents preference by gender and emotion. The results showed that there is significant relationship between 'Happy' emotion and 'Comedy Program' preference and men are more prefer it than women. However, it does not reveal any significant relationship between 'Sad' emotion and contents preferences but women are slightly more prefer 'Comedy Program' than men. This result supports the Zillmann's 'mood based management', which suggests that the needs for pleasant contents are revealed to relieve sadness when people are in a sad mood. In addition, our finding corresponds with Oliver's insistence on meeting all four factors, insight, meaningfulness, understanding and reflection, rather than just pleasure for more satisfaction. This study focused on temporary emotional factors and contents and additionally on effect of users' emotion, personality and preference on type of contents consumption. This relationship between emotions and contents study would suggest the better direction for developing smart devices with great contents usability and user satisfaction in the future.

• Journal of Bio-Environment Control
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• v.18 no.4
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• pp.309-315
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• 2009

Maintenance of adequate soil water content during the period of crop growth is necessary to support optimum plant growth and yields. A better understanding of soil water movement for precision irrigation would allow efficient supply of water to crops, thereby resulting in minimization of water drainage and contamination of ground water. This research reports on the characterization of spatial and temporal variations in water contents through three different textured soils, such as loam, sandy loam, and loamy sand, when water is applied on the soil surface using an one-line drip irrigation system and the soils are dried after the irrigation stops, respectively. Water contents through each soil profile were continuously monitored using three Sentek probes, each consisting of three capacitance sensors at 10, 20, and 30cm depths. Spatial variability in water content for each soil type was strongly influenced by soil textural class. There were big differences in wetting pattern and the rate of downward movement between loam and sandy loam soils, showing that the loam soil had a wider wetting pattern and a slower rate of downward movement than did the sandy loam soil. The wetting pattern in loamy sand soil was not apparent due to a low variability in water content (< 10%) by a lower-water holding capacity as compared to those measured in the loam and sandy loam soils, implying that the rate of water drainage below a depth of 30cm was high. When soils were dried, there were highly exponential relationships between water content and time elapsed after irrigation stops ($r^2$${\geq}$0.98). It was estimated that equilibrium moisture contents for loam, sandy loam, and loamy sand soils would be 17.6%, 6.2%, and 4.2%, respectively.

• The Korean Journal of Nuclear Medicine Technology
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• v.19 no.2
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• pp.93-101
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• 2015

Purpose In SPECT image, scatter count is the cause of quantitative count error and image quality degradation. Thus, a wide range of scatter correction(SC) methods have been studied and this study is to evaluate the accuracy of CT based SC(CTSC) used in SPECT/CT as the comparison with existing energy window based SC(EWSC). Materials and Methods SPECT/CT images were obtained after filling air in order to acquire a reference image without the influence of scatter count inside the Triple line insert phantom setting hot rod(74.0 MBq) in the middle and each SPECT/CT image was obtained each separately after filling water instead of air in order to derive the influence of scatter count under the same conditions. In both conditions, Astonish(iterative : 4 subset : 16) reconstruction method and CT attenuation correction were commonly applied and three types of SC methods such as non-scatter correction(NSC), EWSC, CTSC were used in images filled with image. For EWSC, 9 sub-energy windows were set additionally in addition to main(=peak) energy window(140 keV, 20%) and then, images were acquired at the same time and five types of EWSC including DPW(dual photo-peak window)10%, DEW(dual energy window)20%, TEW(triple energy window)10%, TEW5.0%, TEW2.5% were used. Under the condition without fluctuations in primary count, total count was measured by drawing volume of interest (VOI) in the images of the two conditions and then, the ratio of scatter count of total counts was calculated as percent scatter fraction(%SF) and the count error with image filled with water was evaluated with percent normalized mean-square error(%NMSE) based on the image filled with air. Results Based on the image filled with air, %SF of images filled with water to which each SC method was applied is NSC 37.44, DPW 27.41, DEW 21.84, TEW10% 19.60, TEW5% 17.02, TEW2.5% 14.68, CTSC 5.57 and the most scattering counts were removed in CTSC and %NMSE is NSC 35.80, DPW 14.28, DEW 7.81, TEW10% 5.94, TEW5% 4.21, TEW2.5% 2.96, CTSC 0.35 and the error in CTSC was found to be the lowest. Conclusion In SPECT/CT images, the application of each scatter correction method used in the experiment could improve the quantitative count error caused by the influence of scatter count. In particular, CTSC showed the lowest %NMSE(=0.35) compared to existing EWSC methods, enabling relatively accurate scatter correction.

• The Korean Journal of Nuclear Medicine Technology
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• v.16 no.1
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• pp.70-75
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• 2012

Purpose: It is important to acquire accurate data because the SPECT scan affected by various physical factors. The aim of this study was to compare the uniformity when both centers were matched or mismatched differed from position of heart in COR. Materials and methods: The images were acquired with cylindrical uniform phantom (6.7 cm diameter, 9 cm length) and heart insert phantom using Cardio MD SPECT system (Philips, USA). The phantoms were positioned on COR as well as four different points which were 10 cm above, below, left and right side from the COR. The counts from the both edge of cylindrical uniform phantom and those from the both wall of heart insert phantom were compared by using vertical and horizontal line profile. In addition, the qualitative evaluation was performed with heart insert phantom images and volunteer test. Results: In heart insert phantom study, the differences of counts between COR and 10 cm above, below, left and right point of COR were 1.1, 4.1, 4.9, 2.2 and 0.9% using T-A curve for horizontal view. In case of vertical view of COR 3.9, 21.9, 3.5, 23.9, 14.0% were shown. In cylindrical phantom study, the differences of counts between COR and 10 cm above, below, left and right point of COR were 4.3, 0.3, 3.3, 2.6 and 0.7% using T-A curve for horizontal view. In case of vertical view of COR 2.7, 3.0, 1.0, 0.3, 3.4% were shown. For qualitative evaluation, the images at COR were the most uniform for both of heart insert phantom and volunteer test, whereas other four positions showed somewhat distorted images. Conclusion: It showed the most uniform images when COR is matched with the heart. Therefore, we can expect that distortion which increased or decreased of myocardial perfusion will be prevented by matching the heart and COR when positioning. Furthermore, the accuracy of diagnosis will be improved as well.

• The Korean Journal of Nuclear Medicine
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• v.33 no.5
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• pp.439-451
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• 1999

Purpose : It is important to differentiate malignant from benign lesions of intraocular masses in choosing therapeutic plan. Biopsy of intraocular tumor is not recommended due to the risk of visual damage. We evaluated the usefulness of F-18-FDG PET imaging in diagnosing intraocular neoplasms. Materials and Methods: F-18-FDG PET scan was performed in 13 patients (15 lesions) suspected to have malignant intraocular tumors. There were 3 benign lesions (retinal detachment, choroidal effusion and hemorrhage) and 10 patients with 12 malignant lesions (3 melanomas, 7 retinoblastomas and 2 metastatic cancers). Regional eye images ($256{\times}256$ and $128{\times}128$ matrices) were obtained with or without attenuation correction. Whole body scan was also performed in eight patients (3 benign and 6 malignant lesions). Results: All malignant lesions were visualized while all benign lesions were not visualized. The mean peak standardized uptake value (SUV) of malignant lesions was $2.64{\pm}0.57g/ml$. There was no correlations between peak SUV and tumor volume. Two large malignant lesions ($> 1000 mm^3$) showed hot uptake on whole body scan. But two medium-sized lesions ($100-1000mm^3$) looked faint and two small ($<100mm^3$) lesions were not visualized. The images reconstructed with $256{\times}256$ matrix showed lesions more clearly than those with $128{\times}128$ matrix Conclusion: F-18-FDG PET scan is highly sensitivity in detecting malignant intraocular tumor For the evaluation of small-sized intraocular lesions, whole body scan is not appropriate because of low sensitivity. A regional scan with sufficient acquisition time is recommended for that purpose. Image reconstruction in matrix size of $256{\times}256$ produced clearer images than the ones in $128{\times}128$, but it does not affect the diagnostic sensitivity.

• Journal of IKEEE
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• v.15 no.2
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• pp.179-189
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• 2011

This paper presents an SVC based multi-channel transmission technique. Transmission of high definition multimedia and its service efficiency can be significantly improved by the proposed method. In this method, the HD stream is divided into the two layer streams, i.e., a base layer stream and an enhancement layer stream. The divided streams are transmitted through a primary channel and an auxiliary channel, respectively. The proposed technique provides a noble mode switching technique which enables a seamless service of HD multimedia even under the conditions of abrupt and intermittent deterioration of the auxiliary channel. When the enhancement layer stream is disrupted by the channel monitoring in the mode switching algorithm, the algorithm works further to maintain the spatial and time resolution of the HD multimedia by upsampling and interpolating the base layer stream, consequently serving for the non disrupted play of the media. Moreover, the adoption of an adaptive switching algorithm significantly reduces the frequency of channel disruption avoiding the unnecessary switching for the short period variations of the channel. The feasibility of the proposed technique is verified through the simulation study with an example application to the simultaneous utilization of both Ku and Ka bands for HD multimedia broadcasting service. The rainfall modeling and the analysis of the satellite channel attenuation characteristics are performed to simulate the quality of service performance of the proposed HD broadcasting method. The simulation results obtained under a relatively poor channel (weather) situations show that the average lasting period of enhancement layer service is extended from 9.48[min] to 23.12[min] and the average switching frequency is reduced from 3.84[times/hour] to 1.68[times/hour]. It is verified in the satellite example that the proposed SVC based transmission technique best utilizes the Ka band channel for the service of HD broadcasting, although it is characterized by its inherent weather related poor reliability causing severe limitations in its independent application.

• The Korean Journal of Rheology
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• v.10 no.4
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• pp.234-246
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• 1998

The objective of this study is to investigate the correlation between steady shear flow (nonlinear behavior) and dynamic viscoelastic (linear behavior) properties for concentrated polymer solutions. Using both an Advanced Rheometic Expansion System(ARES) and a Rheometics Fluids Spectrometer (RFS II), the steady shear flow viscosity and the dynamic viscoelastic properties of concentrated poly(ethylene oxide)(PEO), polyisobutylene(PIB), and polyacrylamide(PAAm) solutions have been measured over a wide range of shear rates and angular frequencies. The validity of some previously proposed relationships was compared with experimentally measured data. In addition, the effect of solution concentration on the applicability of the Cox-Merz rule was examined by comparing the steady flow viscosity and the magnitude of the complex viscosity Finally, the applicability of the Cox-Merz rule was theoretically discussed by introducing a nonlinear strain measure. Main results obtained from this study can be summarized as follows : (1) Among the previously proposed relationships dealt with in this study, the Cox-Merz rule implying the equivalence between the steady flow viscosity and the magnitude of the complex viscosity has the best validity. (2) For polymer solutions with relatively lower concentration, the steady flow viscosity is higher than the complex viscosity. However, such a relation between the two viscosities is reversed for highly concentrated polymer solutions. (3) A nonlinear strain measure is decreased with increasing stran magnitude, after reaching the maximum value in small strain range. This behavior is different from the theoretical prediction demonstrating the shape of a damped oscillatory function. (4) The applicability of the Cox-Merz rule is influenced by the $\beta$ value, which indicates the slope of a nonlinear stain measure (namely, the degree of nonlinearity) at large shear deformations. The Cox-Merz rule shows better applicability as the $\beta$ value becomes smaller.

• Journal of radiological science and technology
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• v.29 no.3
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• pp.141-145
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• 2006

In this study, $Eu^{2+}$ ion was used as an activator in order to enhance the PL(photoluminescene) and PSL(photostimulated luminescence) intensity of $MCl_2:Eu^{2+}$(M = Ca, Sr, Ba)phosphors and the chracteristics of PL and PSL of the phosphors were investigated. The emission of $MCl_2:Eu^{2+}$(M = Ca, Sr, Ba) phosphors shows a shift wavelength when the host caution changes. The optimal preparing conditions of $CaCl_2:Eu^{2+}$ phosphor were 0.5 mol％ of $EuCl_2$ and the sintering temperature were $745^{\circ}C$, 45 min. in $H_2$ atmosphere. The PL and PSL spectra of $CaCl_2:Eu^{2+}$ locate in the range of $365{\sim}388\;nm$, peaking at 370 and 380 nm. The optimal preparing conditions of $BaCl_2:Eu^{2+}$ phosphor were 0.5 mol％ of $EuCl_2$ and the sintering temperature were $905^{\circ}C$, 45 min. in $H_2$ atmosphere. The PL and PSL spectra of $BaCl_2:Eu^{2+}$ locate in the range of $370{\sim}460\;nm$, peaking at 398 nm. The optimal preparing conditions of $SrCl_2:Eu^{2+}$ phosphor were 0.5mol％ of $EuCl_2$ and the sintering temperature were $840^{\circ}C$, 45min. in $H_2$ atmosphere. The PL and PSL spectra of $SrCl_2:Eu^{2+}$ locate in the range of $380{\sim}440\;nm$, peaking at 407 nm. The dose response of the $MCl_2:Eu^{2+}$(0.5 mol%)(M = Ba, Sr) phosphors were linear within $0.25{\sim}200\;mGy$ of 100 kV X-ray and the PSL intensity of the $SrCl_2:Eu^{2+}$ and $BaCl_2:Eu^{2+}$ phosphors faded to approximately 60 and 40% respectively after 120 min at room temperature.