• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.1
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• pp.119-125
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• 2018

The particle based computational fluid dynamics (CFD) method, which follow Lagrangian approach for fluid dynamics, fluid particle behavior by tracking all particle calculation physical quantities of each particle. According to basic concept of particle based CFD method, it is difficult to satisfy continuum theory and measure influences from neighboring particle. Article number density and weight function were used to solve aforementioned issue. Difficulties continuum mean simulate non-continuum particles such as solid including granular and sand. In this regard, the particle based CFD method modified solid particle problems by replacing viscous and surface tension forces friction and drag forces. In this paper, particle interaction model for solid particle friction model implemented to simulate solid particle problems. The broken dam problem, which is common to verify particle based CFD method, used fluid or solid particles. The angle of repose was observed in the simulation results the solid particle not fluid particle.

• Journal of Korea Water Resources Association
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• v.43 no.7
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• pp.657-666
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• 2010

The adjustment processes of mining pits in the disturbed channels by sand or gravel mining were investigated by laboratory experiments in this study. The pit migrated with speed when the river bed was steep. The pit migrated slow and steady when the pit was filling with sand, but the pit migrated with speed after the filling processes was finished. The submerged angle of repose in the pit was nearly constant during the pit was filling. The pit was filled with sand with speed as the channel slope was increased. It took time for the pit to be filled with sand as the pit dimension was increased. This meant that the disturbed channels by sand or gravel mining to adjust the new environment was dependent on the slope of the channels and the dimension of the pits. The dimensionless pit length was short and the dimensionless pit depth was shallow as the time was increased. The dimensionless pit depth was shallow, but the dimensionless pit migration speed was increased as the dimensionless shear velocity and the migration speed of the pit were increased. The dimensionless pit depth was increased with the dimensionless bar migration speed. The shape of the pit was deformed and migrated downstream in accordance with the location and shape of the biased bar front which was developed upstream.

• The Journal of Engineering Geology
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• v.21 no.4
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• pp.281-293
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• 2011

We investigated the causes and characteristics of a landslide at Hwangryeong Mountain, Busan, based on aerial photos, annual precipitation data, rock fracture patterns, and geomorphic features using GIS Software, and a statistical analysis of tilted trees. The analyzed slope shows evidence of a previous slope failure event and the possibility of future failures. Although the NW-SE trending slope was relatively stable until 1975, a large-scale slope failure occurred between 1975 and 1985 due to complex factors, including favorably oriented geologic structures, human activity, and heavy rain. This indicates that a detailed study of geologic structures, slope stability, and rainfall characteristics is important for slope cuttings that could be a major factor and cause of urban landsliding events. The statistic analysis of tilted trees shows a slow progressive creeping type of mass wasting with rock falls oblique to the dip of the slope, with the slope having moved towards the west since 1985. A concentration of tree tilting has developed on the northwestern part of the slope, which could reach critical levels in the future. The analysis of deformed trees is a useful tool for understanding landslides and for predicting and preventing future landslide events.

• Food Science and Preservation
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• v.23 no.5
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• pp.654-659
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• 2016

This study was designed to compare the quality characteristics of spray-dried (SD) and freeze-dried (FD) Pueraria thunbergiana extracts powder hot water extracts. Quality characteristics of the SD and FD powder including moisture content, color value, water absorption index, water solubility index, dynamic angle and antioxidant activities were evaluated. The moisture content of SD powder (1.50%) was lower than that of FD powder (2.92%). $L^*$ and $b^*$ values of SD powder was lower than of FD powder. The water absorption index was higher in FD powder (1.40) and water solubility index in SD powder (94.10%) was higher than that FD powder (90.69%). Dynamic angle of SD powder ($36.46^{\circ}$) was higher than that of FD powder ($33.30^{\circ}$). The DPPH radical scavenging activities of 5 mg/mL solution of SD powder and FD powder were 85.38 mg/mL, 59.38 mg/mL, respectively. And, the same trend was observed for the ABTS radical scavenging activities of the drying powder as that observed for their DPPH radical scavenging activities. There were relatively higher contents of phenolic compounds in SD powders than in FD powders. In conclusion, spray-dried Pueraria thunbergiana extracts showed the high WSI, polyphenol, DPPH and ABTS radical scavenging activities and low moisture content and dynamic angle than freeze dried powder.

• Journal of the Korean Geosynthetics Society
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• v.21 no.4
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• pp.101-109
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• 2022

This study describes the results of model experiment to analyze the effect of backfill material types on the behavior of underground facility. In the model experiment, backfill materials around the existing underground facility were applied with soil (Jumunjin standard sand) and CLSM. The displacement of underground facility was analyzed for each excavation stage considering the separation distance between the excavation surface and the backfill area based on the experimental results. When soil was applied as a backfill material, the soil on the back of the excavation surface collapsed by excavation and formed an angle of repose, and the process of slope stability was repeated at each excavation stage. In addition, the displacement of underground facility began to occur in the excavation stage that the failure line of soil passes the installation location of the underground facility. When CLSM was applied as a backfill material, there was almost no horizontal and vertical displacement of the ground regardless of the separation distance from the excavation surface even when excavation proceeded to the backfill depth. Therefore, this result showed that it can have a resistance effect against the lateral earth pressure generated and the collapse of the original ground by adjacent excavation, if a backfill material with high stiffness such as CLSM is applied.

• Journal of Broadcast Engineering
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• v.7 no.3
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• pp.211-218
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• 2002

This paper introduces the HD 3DTV camera and 3DTV receiver that are compatible with the ATSC HDTV broadcasting system. The developed 3DTV camera is based on stereoscopic techniques, and it has control function to control both left and right zoom lens simultaneously and to control the vergence. Moreover, in order to control the vergence manually and to eliminate the synchronization problem of the both images, the 3DTV camera has the 3DTV video multiplexing function to combine the left and right images into the single image. The developed 3DTV signal, and it has the various analog/digital interfaces. The performance of the developed system is confirmed by shooting the selected soccer game in 2002 FIFA KOREA/JAPANTM World Cup and by broadcasting the match. The HD 3DTV camera and receiver will be applied to the 3DTV industries such as 3D movie, 3D game, 3D image processing, 3DTV broadcasting system, and so on.

• Journal of Broadcast Engineering
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• v.17 no.1
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• pp.1-16
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• 2012

In order to improve the workflow of 3D video production, this paper analyzes the visual fatigue caused from distortions in 3D video production stage through a set of subjective visual assessment tests. To establish a set of objective indicators for subjective visual tests, various distortions in production stage are investigated to be categorized into 7 representative visual-fatigue-producing factors, and to conduct visual assessment tests for each selected category, 4 test video clips are produced by combining the extent of camera movement as well as the object(s) movement in the scene. Each produced test video is distorted to reflect each of the selected 7 visual-fatigue-producing factors, and we set 7 levels of distortion for each factor, resulting in 196 5-second-long video clips for testing. Based on these test materials and the recommendation of ITU-R BT.1438, subjective visual assessment tests are conducted by 101 applicants. The test results provide a relative importance and the tolerance limit of each visual-fatigue-producing factor, which corresponds to various distortions in 3D video production field.

• Korean Journal of Optics and Photonics
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• v.21 no.3
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• pp.111-117
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• 2010

A 780 nm monolithic individually addressable 8-beam diode laser with 10mW optical power was developed for use in a laser scanning unit. Beam to beam spacing is $30\;{\mu}m$ and an air bridge interconnection process was developed for individual operations. From electrical and optical characteristic measurements, the developed device is a suitable optical source for a high speed laser scanning unit in multi-function printing systems and laser beam printers.

• Journal of the Korean Society of Food Science and Nutrition
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• v.41 no.9
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• pp.1320-1325
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• 2012

This study investigated the bulk properties of red pepper powders according to drying method and variety. Bulk density, compressive characteristics, irrecoverable work, dynamic angle, and stress relaxation were investigated. Loose bulk density ranged between 0.420 $g/cm^3$ for Cheongyang cultivar and 0.427 $g/cm^3$ for Hanbando cultivar by hot-air drying. The highest tapped bulk density was 0.586 $g/cm^3$ for Hanbando cultivar by far-infrared drying and the lowest value was 0.523 $g/cm^3$ for Hanbando cultivar by sun drying. Hausner ratio reached a maximum value of 1.370 for Hanbando cultivar by far-infrared drying. Compressibility ranged between 0.0016 for Cheongyang cultivar by sun drying and 0.0023 for Hanbando cultivar by far-infrared drying. Compression ratio reached a maximum value of 1.032 for Hanbando cultivar by hot-air drying. Dynamic angle of repose ranged between 37.47 and $42.97^{\circ}$. Irrecoverable work ranged between 76.0 and 81.7%. Relaxation reached a maximum value of 24.31% for Cheongyang cultivar by far-infrared drying.

• Journal of Korean Society of Forest Science
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• v.82 no.4
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• pp.354-365
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• 1993

The purpose of this investigation is to point out the physical fixation and stability of banking slopes of forest roads by invasion of trees. We investigated the situations of sediment discharge and coverage of invaded trees at banking slopes of forest roads. The coverage of invaded trees were calculated from crown injection based on the stable slope and was compared with length of slope, slope gradient, and passage years after construction of forest road. 1. We investigated on the sediment discharge and the invasion of trees at banking slopes, which were actually observed 8 forest roads of Kyonggi-Do and Kangwon-Do. 2. There was no physical stability of the banking slope due to the surface erosion and slope failure, but the tree invasions were active at the stable plots. 3. The length of slope was constructed to 4.0m to 61.0m and recent forest road was mainly constructed to the slopes longer than 30m. There was strong regional effect between the length of slope and the coverage of invaded trees and the above two factors were inversely proportional to each other. 4. There was no significant relationship between the slope gradient and the coverage of invaded trees and the slope constructed within the angle of repose showed the relatively high coverage of invaded trees. 5. There was no significant relationship between the passage years and the coverage of invaded trees in the same investigative region after the construction of forest road. But there was a gradually increasing relationship of tree invasion between above two factors. However, there was some limitation to expect the invasion of the tree species. 6. In the light of the above results, we suggest that the construction of forest road may need foundation work and vegetation work simultaneously for the physical stability to make the environment of tree plantation and that the reasonable increase of construction cost of forest road may be prior to the other factors.