• Title/Summary/Keyword: shape of the earth

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Occurrence Form of an Intrusive Welded Tuff in Geumseongsan Caldera (금성산(金城山) 칼데라내의 관입용결응회암(貫入熔結凝灰岩)의 산출형태(産出形態))

  • Hwang, Sang Koo;Lee, Gi-Dong;Kim, Sang Wook;Lee, Jae Young;Lee, Yoon Jong;Hwang, Jae Ha;Kim, Dong Hak
    • Economic and Environmental Geology
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    • v.28 no.4
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    • pp.415-423
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    • 1995
  • A welded tuff with a near-vertical parataxitic fabric crops out as an elliptical shape($500{\times}350m$) in horizontal section, the Geumseongsan volcanic field. It intrudes the Cretaceous sedimentary rocks of the upper Hayang Group, surge tuff and rhyolite of the Geumseongsan volcanic complex. Generally it displays an ubiquitous, steeply inward-dipping welding foliation, subparallel to the margins of the intrusion, and a subvertically inward-inclined lineation defined by extremely stretched fiammes on the welding foliation plane. These fabrics suggest its overall form may be of an inverted cone-shaped plug representing a flared vent that served as a feeder for extrusive welded ash-flow tuff sheets.

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Synthesis of the Multifunctional Core/Intermediate/Shell Nanoparticles: Tunable Magnetic and Photoluminescence Properties (자성 및 발광 특성이 조절 가능한 다기능 코어/중간체/쉘 나노 입자 합성)

  • Kim, Mun-Kyoung;Kim, Seyun;Moon, Kyoung-Seok;Shin, Weon Ho;Jeong, Hyung Mo
    • Journal of Powder Materials
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    • v.26 no.6
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    • pp.463-470
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    • 2019
  • Fe3O4/SiO2/YVO4:Eu3+ multifunctional nanoparticles are successfully synthesized by facile stepwise sol-gel processes. The multifunctional nanoparticles show a spherical shape with narrow size distribution (approximately 40 nm) and the phosphor shells are well crystallized. The Eu3+ shows strong photoluminescence (red emission at 619 nm, absorbance at 290 nm) due to an effective energy transfer from the vanadate group to Eu. Core-shell structured multifunctional nanoparticles have superparamagnetic properties at 300 K. Furthermore, the core-shell nanoparticles have a quick response time for the external magnetic field. These results suggest that the photoluminescence and magnetic properties could be easily tuned by either varying the number of coating processes or changing the phosphor elements. The nanoparticles may have potential applications for appropriate fields such as laser systems, optical amplifiers, security systems, and drug delivery materials.

Physicochemical Characteristics of Single Asian Dust Storm Particles

  • Ma, Chang-Jin;Mikio kasahara;Hwang, kyung-Chul;Park, Kum-Chan;Park, Seong-Boo;Lee, Jeong-Joo
    • Journal of Korean Society for Atmospheric Environment
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    • v.16 no.E
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    • pp.29-38
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    • 2000
  • For the detailed characterization of atmospheric aerosol, the analysis of single particle is highly valuable. In this study, to investigate the characteristics of single Asian dust storm particles, scanning electron microscope(SEM) coupled with and energy dispersive X-ray microanalyzer(EDX) and micro-PIXE were applied. Sampling was performed at Kyoto University located in Kyoto, Japan, in spring of 1999. Mass concentration during Asian dust storm events was higher roughly 3∼5 times than measured in the season of the highest concentration. Single particles were generally sharp-edged and irregular in shape and contained mostly crustal elements. Significant amount of S in coarse fraction was detected in individual particles. A large particles in coarse fraction existed as the mixture of soil components and S. A good agreement between the result of SEM-EDX analysis and that iof micro-PIXE analysis was obtained in this study.

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EFFECT OF POWDER SIZE ON THE MICROSTRUCTURE AND MAGNETIC PROPERTIES OF Nd-Fe-B MAGNET ALLOY

  • JU-YOUNG CHO;SARDAR FARHAT ABBAS; YONG-HO-CHOA;TAEK-SOO KIM
    • Archives of Metallurgy and Materials
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    • v.64 no.2
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    • pp.623-626
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    • 2019
  • Rare earth Nd-Fe-B, a widely used magnet composition, was synthesized in a shape of powders using gas atomization, a rapid solidification based process. The microstructure and properties were investigated in accordance with solidification rate and densification. Detailed microstructural characterization was performed by using scanning electron microscope (SEM) and the structural properties were measured by using X-ray diffraction. Iron in the form of α-Fe phase was observed in powder of about 30 ㎛. It was expected that fraction of Nd2Fe14B phase increased rapidly with decrease in powder size, on the other hand that of α-Fe phase was decreased. Nd-rich phase diffused from grain boundary to particle boundary after hot deformation due to capillary action. The coercivity of the alloy decreased with increase in powder size. After hot deformation, Nd2Fe14B phase tend to align to c-axis.

Analisys about the Earth Fault Characteristics in the Wireless Power Transmission System of the Electric Vehicle (무선충전 전기자동차 전력공급장치에서의 지락사고 특성 분석)

  • Jung, Jin-Soo;Han, Woon-Ki;Park, Chan-Um;Song, Young-Sang;Lim, Hyun-Sung;Cho, Min-Ho;Lyu, Ji-Yun
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.28 no.12
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    • pp.13-17
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    • 2014
  • In this paper, the risk of electric shock is analyzed through analysis for characterization of potential distribution analysis and ground fault current analysis near the area where there are occurred a ground fault at electric vehicle wireless charging system using 20kHz. Studies for electric vehicle wireless charging system are in the works for development of efficiency increase, pickup shape design and communication module as a fundamental research step. But the research related to electrical safety and is still scarce state so that more studies are necessary to commercialize. As a result of analysis, it is verified that induced voltage is arisen more up to 45V near the a area of accident during ground fault and fault current has been maintained continuously without clearing fault condition by operating characteristics for circuit breaker and inverter.

Grain Size Analysis by Hot-Cooling Cycle Thermal Stress at Y-TZP Ceramics using Full Width at Half Maximum(FWHM) of X-ray Diffraction (X-ray 회절의 반치전폭(FWHM)을 이용한 Y-TZP세라믹스에서 반복 열응력에 의한 입계크기 분석)

  • Choi, Jinsam;Park, Kyu Yeol;Kong, Young-Min
    • Korean Journal of Materials Research
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    • v.29 no.4
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    • pp.264-270
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    • 2019
  • As a case study on aspect ratio behavior, Kaolin, zeolite, $TiO_2$, pozzolan and diatomaceous earth minerals are investigated using wet milling with 0.3 pai media. The grinding process using small media of 0.3 pai is suitable for current work processing applications. Primary particles with average particle size distribution D50, ${\sim}6{\mu}m$ are shifted to submicron size, D50 ${\sim}0.6{\mu}m$, after grinding. Grinding of particles is characterized by various size parameters such as sphericity as geometric shape, equivalent diameter, and average particle size distribution. Herein, we systematically provide an overview of factors affecting the primary particle size reduction. Energy consumption for grinding is determined using classical grinding laws, including Rittinger's and Kick's laws. Submicron size is obtained at maximum frictional shear stress. Alterations in properties of wettability, heat resistance, thermal conductivity, and adhesion increase with increasing particle surface area. In the comparison of the aspect ratio of the submicron powder, the air heat conductivity and the total heat release amount increase 68 % and 2 times, respectively.

Optimal Design of Axial Type Brushless DC Motor Using 3-D FEM (3차원 유한요소법을 이용한 축방향 자속형 브러시리스 DC 전동기 최적 설계)

  • Hong, Sun-Ki
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.19 no.1
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    • pp.143-147
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    • 2005
  • In this paper, an axial type brushless DC motor which has double rotors using rare-earth magnet pieces is designed. This kind of motor has shorter axial length and is easier to assemble than the radial type motors. To get enough torque, NdFeB magnet is used and for the cost of production, the magnets are segmented to rectangle or disk shape. To design this motor, a equivalent circuit is adopted and the air-gap density is calculated using 3D finite element method to get exact parameters. The design variables are optimized with genetic algorithm. From the results of the simulations, the reference of the axial type BLDC motors can be obtained.

3-D gravity terrain inversion for high resolution gravity data analysis

  • Lee Heuisoon;Park Gye-Soon;Kwon Byung-Doo;Oh Seok Hoon;Yang Junmo
    • 한국지구물리탐사학회:학술대회논문집
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    • 2003.11a
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    • pp.379-382
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    • 2003
  • In gravity data correction process, mass effect of the upper part of base level is removed with Bouguer density. Usually, Bouguer density is estimated as a mean density in the field area. But, this may causes a serious problem when ore body is in the area. To overcome this problem, we tried to apply a new method mixing up mass corrections and inversion (3DGTI). 3-D Gravity Terrain Inversion (3DGTI) includes information of topography and distribution of Bouguer density. For this method does not remove the mass effect above base level, it is no longer useless to use Bouguer density. Numerical model tests have shown that the 3DGIT successfully retrieves the anomalous subsurface density distribution of both surface and deeper layers. Model tests shows that this method shows better results than those of conventional one, especially when main target is ore body. The inversion result well delineates the three-dimensional shape of the intruded granite body and basement.

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REAL-TIME 3D SIMULATION INFRASTRUCTURE FOR PRACTICAL APPLICATION OF HIGH-RESOLUTION SATELLITE IMAGERY

  • Yoo, Byoung-Hyun;Brotzman, Don;Han, Soon-Hung
    • Proceedings of the KSRS Conference
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    • 2008.10a
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    • pp.155-158
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    • 2008
  • The needs for digital models of real environment such as 3D terrain or cyber city model are increasing. Most of applications related with modeling and simulation require virtual environment constructed from geospatial information of real world in order to guarantee reliability and accuracy of the simulation. The most fundamental data for building virtual environment, terrain elevation and orthogonal imagery is acquired from optical sensor of satellite or airplane. Providing interoperable and reusable digital model is important to promote practical application of high-resolution satellite imagery. This paper presents the new research regarding representation of geospatial information, especially for 3D shape and appearance of virtual terrain, and describe framework for constructing real-time 3D model of large terrain based on high-resolution satellite imagery. It provides infrastructure of 3D simulation with geographical context. Details of standard-based approach for providing infrastructure of real-time 3D simulation using high-resolution satellite imagery are also presented. This work would facilitate interchange and interoperability across diverse systems and be usable by governments, industry scientists and general public.

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Aspect Ratio Behavior of Grinding Particles with Variation of Particle Size by Wet Grinding (습식분쇄에 의한 입자크기 변화에 따른 분쇄입자의 종횡비 거동)

  • Choi, Jin Sam
    • Korean Journal of Materials Research
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    • v.30 no.5
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    • pp.223-230
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    • 2020
  • As a case study on aspect ratio behavior, Kaolin, zeolite, TiO2, pozzolan and diatomaceous earth minerals are investigated using wet milling with 0.3 mm media. The grinding process using small media of 0.3 pai is suitable for current work processing applications. Primary particles with average particle size distribution D50, ~6 ㎛ are shifted to submicron size, D50 ~0.6 ㎛ after grinding. Grinding of particles is characterized by various size parameters such as sphericity as geometric shape, equivalent diameter, and average particle size distribution. Herein, we systematically provide an overview of factors affecting the primary particle size reduction. Energy consumption for grinding is determined using classical grinding laws, including Rittinger's and Kick's laws. Submicron size is obtained at maximum frictional shear stress. Alterations in properties of wettability, heat resistance, thermal conductivity, and adhesion increase with increasing particle surface area. In the comparison of the aspect ratio of the submicron powder, the air heat conductivity and the total heat release amount increase 68 % and 2 times, respectively.