• The Bulletin of The Korean Astronomical Society
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• v.36 no.2
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• pp.155.1-155.1
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• 2011

The Korea Astronomy and Space Science Institute (KASI) and the Department of Astronomy at the University of Texas at Austin (UT) are developing a near infrared wide-band high resolution spectrograph, IGRINS (Immersion Grating Infrared Spectrograph). The white-pupil design of the instrument optics uses 7 cryogenic mirrors including 3 aspherical off-axis collimators and 4 flat fold mirrors. Two of the 3 collimators are H- and K-band pupil transfer mirrors and they are designed as compensators for the system alignment in each channel. Therefore, their mount design will be one of the most sensitive parts in the IGRINS optomechanical system. The other flat fold mirrors are designed within the limited area. Each of those includes the features of 3 axial hard points and 2 radial hard points with one spring plunger in order for the proper deflection of the mirror. The design work will include the computer-aided 3D modeling and finite element analysis (FEA) to optimize the structural stability and the thermal behavior of the mount models. The mount body will also include a tip-tilt and translation adjustment mechanism to be used as the alignment compensators.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.19 no.4 s.74
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• pp.369-374
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• 2006

This paper describes dynamic characteristics of a power transmission tower consisting of lots of power lines and insulators. A numerical 3D modeling for the static, dynamic and buckling analyses of the power transmission tower is presented considering the case when the power lines are cut. Eigenvalue analysis indicates that the transmission tower shows different behavior comparing to usual structures governed by several low modes. The transmission tower is governed by lots of modes. It is verified that the transmission tower is structurally safe against the static wind and buckling loads. But the structural and buckling safety is not guaranteed when all power lines are cut, which comes to collapse the transmission tower. Further study is in need to overcome such case. Wind dynamic analysis shows that fluctuating wind loads increase the response of the tower.

• Journal of the Korean Association of Geographic Information Studies
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• v.3 no.4
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• pp.1-10
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• 2000

Satellite remote sensing images have much more information compared to a paper map. But these images are generally handled as particular image format gained from optical sensor, and must be processed and analyzed by computer with high priced digital image processing system. For the extraction of digital elevation model(DEM) from satellite image, we used the overlay image by SPOT-3 of Chuncheon area at the Kangwon province. According to the image condition, the precious geometric correction, the bundle adjustment for ortho-image generation and the stereo image mapping by several technical approaches were processed. So that we developed the methods of automatic DEM extraction and efficient stereo image map generation which can improve the digital image processing steps. Also, we applied the multiple direction birdeye view image for modeling and analysis using the remotely sensed overlay images with high resolution.

• Journal of the Society of Naval Architects of Korea
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• v.29 no.4
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• pp.45-57
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• 1992

In this paper, the trends for the standardization of the product model was surveyed, and the product model can be used as concrete means to realize the communication of information between the CAD/CAM softwares, which are used for the design and manufacturing of the complex products such as ships. We have proposed the newly developed methodology for the representation and definition of the ship model on a basis of the product model. And also we have studied the product modeling technology for the aspect of an application, and the object-oriented system technology have been surveyed for the system implementation issues. We would like to verify the consistency and correctness of our proposed representation methodology by using the prototype application model, which is applied to design work of ship compartmentation model. For this purpose we have developed the "OO_COMDEF"(which means the Object-Oriented System for the Compartmentation Definition of ship) program that is applied to the compartmentation model which can be considered as a submodel of the general ship models. The results of research work have been proved that the representation methodology for the ship model based on the product model is an efficient and appropriate scheme for the ship model definitions. Consequently, this methodology can be proposed as a fundamental framework for the development of the shipbuilding CAD/CAM system.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.18 no.4
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• pp.395-403
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• 2000

It is so sensitive that the matter of compensation for private possessions caused in the course of public construction planning is very important. Especially, more logical planning is necessary when the dam be constructed, because it is mainly controlled by the surface of water, and if that planning is made public, artificial change is occurred in land use in that area for the purpose of rising the compensation. In this study, the plan for the application of aerial photo based ortho image was drew up for solving these problems and for the rational, rapid compensation. Ortho image was made by aerial photo, used as reading material for the change in land use. The modeling of drainage basin, came under the planning surface of water, and the 3D simulation were performed for the scene analysis, the change understanding in land use for a lot number in a certain period by overlapping the digital image, the digital land registration map, and the digital topography map as well as the analysis of the admitted land followed by the height of reservoir water.

• Journal of Convergence for Information Technology
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• v.9 no.11
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• pp.125-133
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• 2019

In this paper, probabilistic flood risk maps were produced for levee break caused by possible flood scenarios. The results of the previous studies were employed for flood stages corresponding to hydrological extreme event quantified uncertainties and then predicted the location of a levee breach. The breach width was estimated by combining empirical equation considered constant width and numerical modeling considered uncertainties on compound geotechnical component. Accordingly, probabilistic breach outflow was computed and probabilistic inundation map was produced by 100 runs of 2D inundation simulation based on reliability analysis. The final probabilistic flood risk map was produced by combining probabilistic inundation map based on flood hazard mapping methodology. The outcomes of the study would be effective in establishing specified emergency actin plan (EAP) and expect to suggest more economical and stable design index.

• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.43-43
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• 2015

천수방정식을 사용하는 초기 수치모형은 프로드수($F_4$)가 변화하는 흐름 즉, 상류방향과 하류방향으로 전파하는 홍수파를 동시에 해석하기 위해 중앙 차분기법이 필요한 상류(sub-critical flow)와 흐름방향에 따른 상류이송(upwinding)기법이 필요한 사류(super-critical flow)가 나타나는 흐름해석에서 어려움이 있었다. 하지만, 근사 Riemann 해법의 등장으로 흐름방향에 관계없이 특성선을 따라 정확한 상향가중기법의 적용이 가능하게 되어, 천수방정식을 지배방정식으로 하는 수치모형이 더욱 실용적으로 적용될 수 있도록 하였다. 따라서, 현재 근사 Riemann 해법은 Godunov 형 유한체적 기법, 불연속 Galerkin 혹은 Petrov-Galerkin 유한요소기법 그리고 Boussinesq 기법에도 적용되고 있으며, 특히 Godunov 형 유한체적기법과 결합한 근사 Riemann 해법은 댐 붕괴, 하천 범람 그리고 도시 및 해안지역 침수에 이르기까지 여러 가지 문제에 폭넓게 적용되고 있다. 지금까지 홍수 모델링에 적용된 Godunov형 유한체적모형은 정형 사각격자나 비정형 삼각격자 중에서 한가지의 격자 종류만을 적용한 연구가 주로 수행되었으며, 유한요소모형과 같이 이 두 가지 격자를 동시에 적용한 연구는 거의 이루어지지 않고 있다. 일반적으로, 삼각격자는 사각격자와 는 달리 연구유역의 경계나 지형이 복잡한 경우에도 큰 노력없이 격자의 생성이 가능하나, 격자와 노드의 수가 사각격자보다 많아 계산시간이 많이 소요되는 단점이 있다. 반면, 사각격자는 하천과 같이 선형으로 변하는 지형에 대해서는 표현하기가 용이하며 계산시간의 효율성도 뛰어나다. 본 연구에서는 하천, 도시 그리고 해안지역에서의 효율적이고 정확한 홍수 모델링을 위해 삼각 및 사각격자 그리고 이 두 격자를 동시에 고려한 하이브리드 격자의 적용이 가능한 Godunov형 2차원 유한체적 모형을 개발하였다. 그리고 개발모형을 정확해가 있는 댐 붕괴 문제, 실측치가 존재하는 실험하도 및 실제하도에 삼각, 사각 그리고 혼합격자를 생성하여 모의를 수행하고, 각 적용 격자에 따른 정확성과 효율성 및 장점과 단점을 연구하였다.

• Journal of Preventive Medicine and Public Health
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• v.54 no.3
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• pp.161-165
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• 2021

Objectives: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spreads heterogeneously, disproportionately impacting poor and minority communities. The relationship between poverty and race is complex, with a diverse set of structural and systemic factors driving higher rates of poverty among minority populations. The factors that specifically contribute to the disproportionate rates of SARS-CoV-2 infection, however, are not clearly understood. Methods: We evaluated SARS-CoV-2 test results from community-based testing sites in Los Angeles, California, between June and December, 2020. We used tester zip code data to link those results with United States Census report data on average annual household income, rates of healthcare coverage, and employment status by zip code. Results: We analyzed 2 141 127 SARS-CoV-2 test results, of which 245 154 (11.4%) were positive. Multivariable modeling showed a higher likelihood of SARS-CoV-2 test positivity among Hispanic communities than among other races. We found an increased risk for SARS-CoV-2 positivity among individuals from zip codes with an average annual household income

• Steel and Composite Structures
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• v.42 no.2
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• pp.243-256
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• 2022

A coupled finite element method (FEM)-boundary element method (BEM) for analyzing the hydroelastic response of functionally graded carbon nanotube-reinforced composite (FG-CNTRC) floating plates under moving loads is firstly introduced in this article. For that aim, the plate displacement field is described utilizing a generalized shear deformation theory (GSDT)-based FEM, meanwhile the linear water-wave theory (LWWT)-relied BEM is employed for the fluid hydrodynamic modeling. Both computational domains of the plate and fluid are coincidentally discretized into 4-node Hermite elements. Accordingly, the C1-continuous plate element model can be simply captured owing to the inherent feature of third-order Hermite polynomials. In addition, this model is also completely free from shear correction factors, although the shear deformation effects are still taken into account. While the fluid BEM can easily handle the free surface with a lower computational effort due to its boundary integral performance. Material properties through the plate thickness follow four specific CNT distributions. Outcomes gained by the present FEM-BEM are compared with those of previously released papers including analytical solutions and experimental data to validate its reliability. In addition, the influences of CNT volume fraction, different CNT configurations, water depth, and load speed on the hydroelastic behavior of FG-CNTRC plates are also examined.

• Nuclear Engineering and Technology
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• v.55 no.4
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• pp.1476-1484
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• 2023

Laboratory experiments and point monitoring of reservoir sediments have proven that stable sulfate reduction (SSR) can lower the concentrations of toxic metals and sulfate in acidic groundwater for a long time. Here, we hypothesize that SSR occurred during in situ leaching after uranium mining, which can impact the fate of acid groundwater in an entire region. To test this, we applied a sulfur isotope fractionation method to analyze the mechanism for natural attenuation of contaminated groundwater produced by acid in situ leaching of uranium (Xinjiang, China). The results showed that δ³⁴S increased over time after the cessation of uranium mining, and natural attenuation caused considerable, area-scale immobilization of sulfur corresponding to retention levels of 5.3%-48.3% while simultaneously decreasing the concentration of uranium. Isotopic evidence for SSR in the area, together with evidence for changes of pollutant concentrations, suggest that area-scale SSR is most likely also important at other acid mining sites for uranium, where retention of acid groundwater may be strengthened through natural attenuation. To recapitulate, the sulfur isotope fractionation method constitutes a relatively accurate tool for quantification of spatiotemporal trends for groundwater during migration and transformation resulting from acid in situ leaching of uranium in northern China.