• Journal of the Korean GEO-environmental Society
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• v.22 no.8
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• pp.5-12
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• 2021

Climate change caused by global warming increases the frequency of occurrence of super typhoons and causes various types of sediment disasters such as debris flows in the mountainous area. This study is to evaluate the behavior of debris flow according to the multiplier value of the precipitation characteristics and the quantity of debris flow according to the typhoon category. For the analysis of the debris flow, the finite difference method for time elapse was applied. The larger the typhoon category, the higher the peak value of the flow discharge of debris flow and the faster the arrival time. When the precipitation characteristic multiplier is large, the fluctuation amplitude is high and the bandwidth is wide. When the slope angle was steeper, water discharge increased by 2~2.5 times or more, and the fluctuation of the flow discharge of debris flow increased. All of the velocities of debris flow were included to the class of "Very rapid", and the distribution of the erosion or sedimentation velocity of debris flows showed that the magnitude of erosion increased from the beginning, large-scale erosion occurred, and flowed downstream. The results of this study will provide information for predicting debris flow disasters, structural countermeasures and establishing countermeasures for reinforcing resilience in vulnerable areas.

• Journal of the Korean Society of Radiology
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• v.13 no.4
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• pp.661-666
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• 2019

Diverging collimators is used to obtain reduced images of an object, or to detect a wide filed-of-view (FOV) using a small gamma camera. In the gamma camera using the diverging collimators, the block scintillator, and the pixel scintillator array, gamma rays are obliquely incident on the scintillator surface when the source is located the periphery of the FOV. Therefore, the spatial resolution is reduced because it is obliquely detected in depth direction. In this study, we designed a novel system to improve the spatial resolution in the periphery of the FOV. Using a tapered crystal array to configure the scintillation pixels to coincide with the angle of the collimator's hole allows imaging to one scintillation pixel location, even if events occur to different depths. That is, even if is detected at various points in the diagonal direction, the gamma rays interact with one crystal pixel, so resolution does not degrade. The resolution of the block scintillator and the tapered crystal array was compared and evaluated through Geant4 Application for Tomographic Emission (GATE) simulation. The spatial resolution of the obtained image was 4.05 mm in the block scintillator and 2.97 mm in the tapered crystal array. There was a 26.67% spatial resolution improvement in the tapered crystal array compared to the block scintillation.

• Food Science of Animal Resources
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• v.41 no.5
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• pp.802-815
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• 2021

To investigate the effect of postmortem phases on lamb meat quality, the physicochemical quality, microstructure and water mobility of oyster cut, short loin, knuckle and silverside muscles from Small-Tail Han sheep were evaluated in the pre-rigor, rigor mortis and post-rigor phases. Pre-rigor lamb meat had higher pH and water holding capacity (WHC), whereas lower CIE L^*, b^*, hue angle values than rigor mortis and post-rigor meat (p<0.05). The Warner-Bratzler shear force (WBSF) values were higher in rigor mortis short loin and silverside than their pre-rigor and post-rigor counterparts, pre-rigor short loin had lower WBSF value than its post-rigor counterpart (p<0.05). Muscle fibers shrank laterally and longitudinally during the onset of rigor mortis. Rigor mortis and postrigor lamb meat exhibited wide I-bands, dark A-bands, short sarcomeres and large inter-myofibrillar spaces. The shift of immobilized water to free water and repulsion from the intra-myofibrillar space to the extracellular space result in the increase of water loss in rigor mortis and post-rigor lamb meat. The results of the principal component analysis (PCA) indicated that rigor mortis and post-rigor lamb meat had similar quality properties but different from pre-rigor lamb meat. In conclusion, the lamb meat in the pre-rigor phase had good tenderness, color and WHC. The results of this research could provide some theoretical references for lamb meat production and processing.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.15 no.2
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• pp.103-108
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• 2022

Various studies have been conducted on cloud observation using all-sky images acquired with a wide-angle camera system since the early 21st century, but it is judged that an automatic observation system that can completely replace the eye observation has not been obtained. In this study, to verify the quantification of cloud observation, which is the final step of the algorithm proposed to automate the observation, the cloud distribution of the all-sky image and the corrected image were compared and analyzed. The reason is that clouds are formed at a certain height depending on the type, but like the retina image, the center of the lens is enlarged and the edges are reduced, but the effect of human learning ability and spatial awareness on cloud observation is unknown. As a result of this study, the average cloud observation error of the all-sky image and the corrected image was 1.23%. Therefore, when compared with the eye observation in the decile, the error due to correction is 1.23% of the observed amount, which is very less than the allowable error of the eye observation, and it does not include human error, so it is possible to collect accurately quantified data. Since the change in cloudiness due to the correction is insignificant, it was confirmed that accurate observations can be obtained even by omitting the unnecessary correction step and observing the cloudiness in the pre-correction image.

• Journal of Korea Entertainment Industry Association
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• v.15 no.5
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• pp.85-98
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• 2021

The present thesis is a study about a character actor's characterization from the concept of 'star persona'. Conducted in 2020, this is a follow-up study about a personality actor's characterization. Lee Sung-min was selected due to his wide acting spectrum among domestic actors and his brilliant expression of differing characters as a character actor. The study discusses characterization methods for character actors on the basis of his role of high-ranking North Korean bureaucrat 'Ri Myung-un' in the film 'The Spy Gone North'. Stanislavski claimed that character building or characterization was the pinnacle of the acting art. However, such an expression of personality requires hard work and devotion from an actor. The actor Lee Sung-min practiced the North Korean dialect in order to act the role, and added the way the elite speak in North Korea to this dialect. He achieves a style of acting that raises tensions within the drama by spitting out lines in one breath and by making the audience fixate their gaze within character solo shots for which the character's emotions and lines serve as the core, with the purpose of maximizing dramatic tension and situational reality. Continuity and angle also serve extremely important roles in terms of expressing a character's personality development, affect, and emotions. The present thesis discussed the character development methods for a character actor's role of 'Ri Myung-un' in the film 'The Spy Gone North'.

• Journal of Broadcast Engineering
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• v.28 no.1
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• pp.79-89
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• 2023

A multi-view display is regarded as the most practical technology to provide a three-dimensional effect to a viewer because it can provide an appropriate viewpoint according to the observer's position. But, most multi-view displays with flat shapes have a disadvantage in that a viewer watches 3D images only within a limited front viewing angle. In this paper, we proposed a spherical display using a ball lens with spherical symmetry that provides perfect parallax by extending the viewing zone to 360 degrees. In the proposed system, each projection lens is designed to be packaged into a small modular array, and the module array is arranged in a spherical shape around a ball lens to provide vertical and horizontal parallax. Through the applied optical module, the image is formed in the center of the ball lens, and 3D contents are clearly imaged with the size of about 0.65 times the diameter of the ball lens when the viewer watches them within the viewing window. Therefore, the feasibility of a 360-degree full parallax display that overcomes the spherical aberration of a ball lens and provides a wide field of view is confirmed experimentally.

• Journal of The Korean Astronomical Society
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• v.56 no.2
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• pp.263-275
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• 2023

The Sun-Earth Lagrange point L4 is considered as one of the unique places where the solar activity and heliospheric environment can be observed in a continuous and comprehensive manner. The L4 mission affords a clear and wide-angle view of the Sun-Earth line for the study of the Sun-Earth and Sun-Moon connections from he perspective of remote-sensing observations. In-situ measurements of the solar radiation, solar wind, and heliospheric magnetic field are critical components necessary for monitoring and forecasting the radiation environment as it relates to the issue of safe human exploration of the Moon and Mars. A dust detector on the ram side of the spacecraft allows for an unprecedented detection of local dust and its interactions with the heliosphere. The purpose of the present paper is to emphasize the importance of L4 observations as well as to outline a strategy for the planned L4 mission with remote and in-situ payloads onboard a Korean spacecraft. It is expected that the Korean L4 mission can significantly contribute to improving the space weather forecasting capability by enhancing the understanding of heliosphere through comprehensive and coordinated observations of the heliosphere at multi-points with other existing or planned L1 and L5 missions.

• The korean journal of orthodontics
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• v.34 no.3 s.104
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• pp.253-260
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• 2004

Frictional force between the orthodontic bracket and arch wire during sliding tooth movement is related to many factors, such as the size, shape and material of both the bracket and wire, ligation method and the angle formed between the bracket and wire. There have been clear conclusions drawn in regard to most of these factors, but as to the effect of bracket width on frictional force there are only conflicting studies. This study was designed to investigate the effect of bracket width on the amount of frictional forces generated during clinically simulated tooth movement. Three different widths of brackets $(0.018{\times}0.025'\;standard)$ narrow (2.40mm), medium (3.00mm) and wide (4.25mm) were used in tandem with $0.016{\times}0.022'$ stainless steel wire. Three bracket-arch wire combinations were drawn on for 4 minutes on a testing apparatus with a head speed of 0.5mm/min and tested 7 times each. To reproduce biological conditions, dentoalveolar models were designed with indirect technique using a material with similar elastic properties as periodontal ligament (PDL). In addition, to minimize the effect of ligation force, elastomer was used with added resin, which was attached to the bracket to make up for the discrepancies of bracket width. The results were as follows: 1. Maximum frictional force for each bracket-arch wire combination was: Narrow (2.40mm): $68.09\pm4.69gmf$ Medium (3.00mm): $72.75\pm4.98 gmf$ Wide (4.25mm): $72.59\pm4.54gmf$ 2. Frictional force was increased with more displacement of wire through the bracket slot. 3. The ANOVA psot-hoc test showed that the bracker width had no significant effect on frictional force when tested under clinically simulated conditions(p>0.05).

• Journal of the Korean Society of Radiology
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• v.9 no.4
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• pp.205-211
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• 2015

At a recent medical imaging technology, the major issue of X-ray diagnosis in breast cancer is the early detection of breast cancer and low patient's exposure dose. As one of studies to acquire a monochromatic X-ray, Technologies using multilayer mirror had been preceded. However, a uniform multilayer mirror that consists of uniform thin-film thickness can acquire a monochromatic X-ray only in the partial area corresponds to angle of incidence of white X-ray, so there are limits for X-ray imaging technology applications. In this study, we designed laterally graded multilayer mirror(below GML) that reflects same monochromatic X-ray over the entire area of thin-film mirror, which have the the thickness of the linear gradient that correspond to angle of incidence of white X-ray. By using ion-beam sputtering system added the mask control system we fabricated a GML which has size of $100{\times}100mm^2$. The GML is designed to achieve the monochromatic X-ray of 17.5kev energy and has thin-film thickness change from 4.62nm to 6.57nm(3.87nm at center). It reflects the monochromatic X-ray with reflectivity of more than 60 percent, FWHM of below 2.6keV and X-ray beam width of about 3mm. The monochromatic X-ray corresponded to 17.5keV using GML would have wide application in development of mammography system with high contrast and low dose.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.05a
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• pp.5-5
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• 2011

The research and development of hybrid electric vehicle (HEV), plug-in hybrid electric vehicle (PHEV) and electric vehicle (EV) are intensified due to the energy crisis and environmental concerns. In order to meet the challenging requirements of powering HEV, PHEV and EV, the current lithium battery technology needs to be significantly improved in terms of the cost, safety, power and energy density, as well as the calendar and cycle life. One new technology being developed is the utilization of composite cathode by mixing two different types of insertion compounds [e.g., spinel $LiMn_2O_4$ and layered $LiMO_2$ (M=Ni, Co, and Mn)]. Recently, some studies on mixing two different types of cathode materials to make a composite cathode have been reported, which were aimed at reducing cost and improving self-discharge. Numata et al. reported that when stored in a sealed can together with electrolyte at $80^{\circ}C$ for 10 days, the concentrations of both HF and $Mn^{2+}$ were lower in the can containing $LiMn_2O_4$ blended with $LiNi_{0.8}Co_{0.2}O_2$ than that containing $LiMn_2O_4$ only. That reports clearly showed that this blending technique can prevent the decline in capacity caused by cycling or storage at elevated temperatures. However, not much work has been reported on the charge-discharge characteristics and related structural phase transitions for these composite cathodes. In this presentation, we will report our in situ x-ray diffraction studies on this mixed composite cathode material during charge-discharge cycling. The mixed cathodes were incorporated into in situ XRD cells with a Li foil anode, a Celgard separator, and a 1M $LiPF_6$ electrolyte in a 1 : 1 EC : DMC solvent (LP 30 from EM Industries, Inc.). For in situ XRD cell, Mylar windows were used as has been described in detail elsewhere. All of these in situ XRD spectra were collected on beam line X18A at National Synchrotron Light Source (NSLS) at Brookhaven National Laboratory using two different detectors. One is a conventional scintillation detector with data collection at 0.02 degree in two theta angle for each step. The other is a wide angle position sensitive detector (PSD). The wavelengths used were 1.1950 ${\AA}$ for the scintillation detector and 0.9999 A for the PSD. The newly installed PSD at beam line X18A of NSLS can collect XRD patterns as short as a few minutes covering $90^{\circ}$ of two theta angles simultaneously with good signal to noise ratio. It significantly reduced the data collection time for each scan, giving us a great advantage in studying the phase transition in real time. The two theta angles of all the XRD spectra presented in this paper have been recalculated and converted to corresponding angles for ${\lambda}=1.54\;{\AA}$, which is the wavelength of conventional x-ray tube source with Cu-$k{\alpha}$ radiation, for easy comparison with data in other literatures. The structural changes of the composite cathode made by mixing spinel $LiMn_2O_4$ and layered $Li-Ni_{1/3}Co_{1/3}Mn_{1/3}O_2$ in 1 : 1 wt% in both Li-half and Li-ion cells during charge/discharge are studied by in situ XRD. During the first charge up to ~5.2 V vs. $Li/Li^+$, the in situ XRD spectra for the composite cathode in the Li-half cell track the structural changes of each component. At the early stage of charge, the lithium extraction takes place in the $LiNi_{1/3}Co_{1/3}Mn_{1/3}O_2$ component only. When the cell voltage reaches at ~4.0 V vs. $Li/Li^+$, lithium extraction from the spinel $LiMn_2O_4$ component starts and becomes the major contributor for the cell capacity due to the higher rate capability of $LiMn_2O_4$. When the voltage passed 4.3 V, the major structural changes are from the $LiNi_{1/3}Co_{1/3}Mn_{1/3}O_2$ component, while the $LiMn_2O_4$ component is almost unchanged. In the Li-ion cell using a MCMB anode and a composite cathode cycled between 2.5 V and 4.2 V, the structural changes are dominated by the spinel $LiMn_2O_4$ component, with much less changes in the layered $LiNi_{1/3}Co_{1/3}Mn_{1/3}O_2$ component, comparing with the Li-half cell results. These results give us valuable information about the structural changes relating to the contributions of each individual component to the cell capacity at certain charge/discharge state, which are helpful in designing and optimizing the composite cathode using spinel- and layered-type materials for Li-ion battery research. More detailed discussion will be presented at the meeting.