• 한국진공학회:학술대회논문집
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• 한국진공학회 2009년도 제38회 동계학술대회 초록집
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• pp.378-378
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• 2010

We report the electronic structure of CoFeO-R (R=Hf, La, Nb) thin films studied by x-ray absorption spectroscopy (XAS). These ferrites thin films were prepared by pulsed laser deposition method and characterized by XAS measurements at O K-, Co and Fe L-edges. The O K-edge spectra suggest that there is a strong hybridization between O 2p and 3d electrons of transition metal cations and Fe $L_{3,2}$-edge spectra indicate that Fe-ions exist in $Fe^{2+}$ with tetrahedral site of the spinel structure. Divalent Co ions is also distributed in tetrahedral site with rare earth ions goes to octahedral sites of spinel structure. X-ray magnetic circular dichroism (XMCD) is also used to explain the symmetry and magnetic nature dependence on rare-earth ions.

• Structural Engineering and Mechanics
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• 제85권6호
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• pp.809-823
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• 2023

In this work, dynamic stability analysis of the ball after contacting with the earth in the volleyball game is presented. Via spherical shell coordinate, the governing equations and general boundary conditions of the ball after contacting with the earth in the volleyball game is studied. Via Comsol multi-physics simulation, some results are presented and a verification between the outcomes is studied. Harmonic differential quadrature method (HDQM) is utilized to solve the dynamic equations with the aid of boundary nodes of the current spherical shell structure. Finally, the results demonstrated that thickness, mass of the ball and internal pressure of the ball alters the frequency response of the structure. One important results of this study is influence of the internal pressure. Higher internal pressure causes lower frequency and hence reduces the stability of the ball.

• 천문학회보
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• 제25권2호
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• pp.36-36
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• 2000

• 한국우주과학회:학술대회논문집(한국우주과학회보)
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• 한국우주과학회 2000년도 한국우주과학회보 제9권2호
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• pp.36-36
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• 2000

No Abstract, See Full Text

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2001년도 가을 학술발표회 논문집
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• pp.323-328
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• 2001

In the ordinary reinforced earth wall, which was constructed by incremental construction method, the horizontal deformation of the facing due to the compaction induced horizontal earth pressure was unavoidable. Thus the KOESWall system which are adopted the isolated construction method was developed by I&S Eng. Co., Ltd. in 1999. Due to its systematical feature, KOESWall system is able to minimizes the horizontal deformation of reinforced wall effectively and it can be used as temporary structures more economically without the lacing block. In this report, it is shown that the concept and case histories of KOESWall system as a retaining structures.

• 한국광물학회지
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• 제23권4호
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• pp.403-411
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• 2010

지구물질의 거시적 성질로부터 지구시스템 진화의 실마리를 찾을 수 있으며, 이런 거시적인 물성은 지구물질의 원자구조에 의하여 결정되기 때문에 지구물질의 원자구조(즉, 전자구조)를 파악하는 것은 지구시스템의 현상의 이해에 매우 중요하다. 지구내부의 잘 알려지지 않은 물질들의 원자구조를 규명하기 위하여 최근에는 범밀도함수 이론에 기반한 양자계산이 이용되고 있다. 본 연구에서는 온-포텐셜 선형화 보충 평면파가 이용된 양자계산을 통해 저온석영과 스티쇼바이트에 대한 산소원자 K-전자껍질 에너지-손실 흡수끝-부근 구조(energy-loss near-edge structure; ELNES) 스펙트럼과 각 전자 오비탈에 대한 국소상태밀도(partial local density of states; PLDOS)를 계산하였다. 산소원자 K-전자껍질 ELNES 스펙트럼은 저온석영과 스티쇼바이트의 결정구조에 따라서, 저온석영에서는 ~538 eV에서 세기가 강한 피크가 나타나고 스티쇼바이트에서는 ~537과 ~543 eV에 강한 피크가 나타난다. 이와 같은 결정구조에 따른 산소원자 K-전자껍질 ELNES 스펙트럼의 차이는 지구내부 다양한 결정질과 비결정질 규산염 물질의 산소원자 주변의 환경을 파악하는 중요한 지표로 이용될 수 있다.

• 한국항공우주학회지
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• 제45권10호
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• pp.898-906
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• 2017

본 논문은 우주선의 우주궤도 상에서 받는 외부 열원을 효과적이고 정확하게 계산할 수 있는 방법에 대해 논한다. 우주 외부 열원은 크게 태양직사광, 지구반사광, 지구복사열 세가지로 구분할 수 있다. 본 논문은 지구반사광과 지구복사열이 확산반사 및 방사를 따른다고 가정하고 지구표면을 다수의 구역들로 분할하여 이들과 인공위성 표면과의 반사/복사열을 계산하여 합산하였다. 본 연구에는 이들의 엄밀 적분식을 적용하여 수렴성을 극대화하였으며 많은 경우 정확한 결과를 가져올 수 있음을 알 수 있다. 그리고 외부 열원과 위성 표면 사이의 광선 차폐를 판단하기 위해 KD Tree Ray Tracing을 적용한 인공위성 궤도 열하중 계산 알고리즘을 개발하였다.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2005년도 Proceedings of ISRS 2005
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• pp.741-744
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• 2005

A numerical scattering model for artificial metal structure based on physical optics approximation is developed to identify the height of phase center, and the result is compared with interferometric SAR DEM. The interferometric SAR data were gathered by AIRSAR during PACRIM- II campaign on Jeju Island. Power transmission towers on piedmont pasture along the slopes of Mt. Halla look like elliptic risings in TOPSAR DEM. The heights of risings are quantitatively analyzed using a scattering model in the way of achieving the height of phase centers of power transmission towers. A numerical algorithm is developed on the basis of physical optics approximation. The structure of power transmission tower was decomposed into hundreds of rectangular metal plates, of which the scattering matrix is known in analytic form, and the calculated scattering fields were summed coherently. The effect of direct backscattering component, ground-scatterer component and scatterer-ground component are decomposed and computed individually for each rectangular metal plate. The $\Deltak-radar$ equivalent was used to calculate height of phase center of the scatterer. The heights of a selected power transmission tower and scattering algorithm results give existence and location of the transmission towers but not actual tower heights.

• 자원환경지질
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• 제29권5호
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• pp.615-622
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• 1996

Slope stability analysis was conducted using remote sensing and Geoscientific Information System (GIS) as a part of natural hazard assessment around Chungju area. Landsat TM band 5 and 7 which contain more information about geological structure and geography are chosen and processed to analyse regional geological structure. Through image processing technique such as PCA, HFF, edge detection and enhancement, regional lineament can be mapped and identified. The lineament density map is constructed based on summed length of lineaments per unit area and the study area can be divided into 7 structural domains. Various factors of slope stability analysis such as geology, slope aspect, degree of slope, landcover, water shed as well as characterized structural domain are constructed as a database of GIS. Rating and weighting of each factor for slope stability analysis is decided by considering environmental geological characteristics of study area. Spatial analysis of regional slope stability is examined through overlaying technique of the GIS. The result of areal distribution of slope stability shows that the most unstable area is all over Jaeogae-ni, Hyangsan-ni and Mt. Daedun.

• 국제초고층학회논문집
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• 제4권1호
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• pp.65-73
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• 2015

Detailed finite element (FE) analyses of a full-scale four-story steel frame structure, subjected to consecutive 60% and 100% excitations from the JR Takatori records during the 1995 Hyogoken-Nanbu earthquake, are conducted using E-Simulator. The four-story frame was tested at the largest shake-table facility in the world, E-Defense, in 2007. E-Simulator is a parallel FE analysis software package developed to accurately simulate structural behavior up to collapse by using a fine mesh of solid elements. To reduce computational time in consecutive dynamic time history analyses, static analysis with gravity force is introduced to terminate the vibration of the structure during the analysis of 60% excitation. An overall sway mechanism when subjected to 60% excitation and a story mechanism resulting from local buckling of the first-story columns when subjected to 100% excitation are simulated by using E-Simulator. The story drift response to the consecutive 60% and 100% excitations is slightly smaller than that for the single 100% excitation.