• Environmental Engineering Research
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• v.25 no.4
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• pp.498-505
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• 2020

This study analyzes the velocity and pressure incurred by protruding shapes installed within the inlet part of a pressurized membrane module during operation to determine the fluid flow distribution. In this paper, to find the flow distribution within a module, it investigates the velocity and pressure values at cross-sectional and outlet planes, and 9 sections classified on outlet plane using computational fluid dynamics. From the Reynolds number (Re), the fluid flow was estimated to be turbulent when the Re exceeded 4,000. In the vertical cross-sectional plane, shape 4 and 6 (round-type protrusion) showed the relatively high velocity of 0.535 m/s and 0.558 m/s, respectively, indicating a uniform flow distribution. From the velocity and pressure at the outlet, shape 4 also displayed a relatively uniform fluid velocity and pressure, indicating that fluid from the inlet rapidly and uniformly reached the outlet, however, from detailed data of velocity, pressure and flowrate obtained from 9 sections at the outlet, shape 6 revealed the low standard deviations for each section. Therefore, shape 6 was deemed to induce the ideal flow, since it maintained a uniform pressure, velocity and flowrate distribution.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2007.11a
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• pp.347-352
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• 2007

Recently, automated construction machines have been developed for technically solving construction industry problems such as labor, productivity, quality and the profit decrease. In domestic construction industry, a research for developing an intelligent excavation robot has been performed. The primary objective of this research is to analysis state-of-the art technologies in order to recognize local ground shape in real-time and compute soil volume of earth moving. This research analyzed five elemental technologies for 3D modeling of local ground shape and selected an optimal technology among the five technologies through using AHP method. It is anticipated that the optimal technology selected for 3D modeling of local ground shape can be effectively used to develop the intelligent excavation robot.

• Journal of the Korean earth science society
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• v.32 no.1
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• pp.140-151
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• 2011

This study is to search the problems of schoolyard teaching material developed by pre-service earth science teachers and the critical factors affecting material making. The 258 schoolyard teaching materials was collected from 54 pre-service earth science teachers (male: 18, female: 36) major in Earth Science Education in Jeonju, Korea. The schoolyard teaching materials was greatly influenced by making process type of it and the prior knowledge of pre-service earth science teachers. As schoolyard preference exploratory type rely on their prior knowledge to develop the schoolyard teaching materials, they made use of the limited concepts like fault in material making. But the concept preference exploratory type made use of concepts not accessible to majority of pre-service earth science teachers because they selected a concept from the earth science textbook first of all. The pre-service earth science teachers having wrong prior knowledge selected inappropriate resources, as well as fell into the error of concept connecting. The pre-service earth science teachers having right prior knowledge partly considered only shape of resources, but had a disregard for formation process of it in material making. Accordingly, we need to reflect richly Geological Field Trip and Solid Earth Science to curriculum for earth science teacher education. And we have to educate pre-service earth science teachers to create holistic concept on the geological subject matter knowledge, field based teaching and learning strategy, material making process.

• Journal of The Korean Astronomical Society
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• v.6 no.1
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• pp.9-14
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• 1973

A simple model of the galactic mass distribution consisting of one sphere and two spheroids with different eccentricities is considered. The resulting model is found to be consistent with the recent observations of the galactic rotation as well as suggested shape of the Galaxy.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.2
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• pp.445-450
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• 2016

This paper studied on the influence of naval vessel shape on vertical magnetic field after the vessel was demagnetized. The triangular shape, the rectangular shape and circular shape were adaped from vessel's structual drawings. Magneto-static FEM analysis was performed to obtain the iduced magnetic field due to earth magnetic field for those shapes. During demagnetization process, magnetic field of residual magnetization was observed. The holizontal and vertical magnetic field were calculated depending on vertical bias magnetic field through magnetc component seperation. To demagnetize naval vessel ship, demagnetizing coils shoud be wound more finely in the vow and stern of the ship than it should be in the mid-part of the ship.

• Journal of Positioning, Navigation, and Timing
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• v.12 no.4
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• pp.335-342
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• 2023

Lunar Navigation Satellite System refers to a constellation of satellite providing PNT services on the moon. LNSS consists of main satellite and navigation satellites. Navigation satellites orbiting around the moon and a main satellite moves the area between the moon and the L2 point. The navigation satellite performs the same role as the Earth's GNSS satellite, and the main satellite communicates with the Earth for time synchronization. Due to the effect of the non-uniform shape of the moon, it is necessary to focus on the influence of the lunar gravitational field when designing the orbit simulation for navigation satellite. Since the main satellite is farther away from the moon than the navigation satellite, both the earth's gravity and the moon's gravity must be considered simultaneously when designing the orbit simulation for main satellite. Therefore, the main satellite orbit simulation must be designed through the three-body problem between the Earth, the moon, and the main satellite. In this paper, the orbit simulation tool for main satellite and navigation satellite required for LNSS was designed. The orbit simulation considers the environment characteristics of the moon. As a result of comparing long-term data (180 days) with the commercial program GMAT, it was confirmed that there was an error of about 1 m.

• Journal of the Korean Geotechnical Society
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• v.20 no.4
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• pp.75-88
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• 2004

It is known that the earth pressure acting on the cylindrical retaining wall in cohesionless soils is small than that acting on the retaining wall in plane strain condition due to three dimensional arching effect. In this study, the earth pressure equation considering the earth pressure decrease by horizontal and vertical arching effects, overburden, wall friction, and failure surface slope is proposed. For the purpose of verifying the applicability of proposed equation, model test is performed with apparatuses that can control wall displacement, wall friction, and wall shape ratio. Influence of each factor on the active earth pressure acting on the cylindrical retaining wall is analyzed according to the model test in constant wall displacement condition. The comparison of calculated results with measured values shows that the proposed equations satisfactorily predict the earth pressure distribution on the cylindrical retaining wall.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.5 no.2
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• pp.41-50
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• 1985

The mathematical analysis of the outflow hydrograph resulting from earth dam-break was studied. DBFW(Dam Break Flood Wave) model based on the breach mechanism and reservoir storage equation was developed and was applied to the Teton and Buffalo-Creek dam. The modeling results showed that the shape of outflow hydrograph, peak discharge and failure duration time had a good agreement with the data analyzed by NWS. The breach mechanisms which exert influence on the outflow hydrograph were consisted of geomorphological characteristics of the reservoir, breach mode, breach width and failure duration time. The earth dams in Korea were classified into four types by the reservoir geomorphology, and water surface elevation-failure duration time-peak discharge relationships were also presented. The methodological procedure made in this paper will provide a basic contribution to dam-break study in river system.

• Journal of the Korean Geotechnical Society
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• v.15 no.4
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• pp.167-173
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• 1999

In this paper the failure behavior of the reinforced earth retaining wall structures according to the deformed types of the face was studied by model test using carbon rods. In model test the behavior of the face for the model of the reinforced earth wall was divided into three cases : the displacement of the top part(case 1), the lateral displacement(case 2) and the displacement of the lower part (case 3). The photographic method was applied to examine the failure line of the deformed wall with the naked eye. The failure line shows a parabolic shape for case 1, a large circular arc for case 2 and a logarithmic spiral for case 3 in the experimental results. The design failure line for the coherent gravity structure hypothesis was most similar to the failure line for the case of the lower part displacement.

• Journal of the Korean earth science society
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• v.30 no.1
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• pp.10-18
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• 2009

Two fruit fossils of Albizia miokalkora were collected from the Miocene Duho Formation of Yeonil Group in the northern Pohang Beach and Changpodong, Gyeongsangbug-do, Korea. The legume is flat and long and has 7 rounded seeds. Although the legume fossils are preserved as impression, they show their whole shape well. It is considered that the fossil Albizia might have flourished in a warm temperate climate in East Asia. This discovery is the second record of Albizia from the Neogene of Korea.