• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.2
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• pp.136-142
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• 2010

In this paper, the microstrip antenna for penta-band service is proposed. It is designed for a wide band characteristic based on a monopole line combined with a triangular patch structure which has two slits. Total antenna size is $35\;mm{\times}20\;mm$ and it was fabricated on FR-4 substrate($\varepsilon_r=4.4$) which has $35\;mm{\times}75\;mm{\times}1\;mm$ size and a microstrip line with impedance 50 ohm is used. Experimental result shows the impedance bandwidth($VSWR{\leq}3$) of the proposed antenna operated within GSM/DCS/USPCS/UMTS/Bluetooth frequency band. The resonance frequency of the proposed antenna is 0.92, 1.97, 2.45 GHz and the average gain is -2.18, -0.66, -0.58 dBi. Also, the radiation efficiency is 60, 85, 87%. The fabricated antenna is satisfied with the aimed impedance bandwidth ($VSWR{\leq}3$) in GSM/DCS/ USPCS/UMTS/Bluetooth frequency band.

• The Journal of the Petrological Society of Korea
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• v.26 no.2
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• pp.113-125
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• 2017

We investigates geochemical and tectonic characteristics for the Triassic Bojangsan trachyte in the southern margin of the Imjingang belt. The geochemical signatures of the thracyte are characterized by enrichments of REE and HFS, and show no Nb trough, suggesting that would not experience arc magmatic processes involving continental crustal materials. The trachyte reveals within-plate setting in tectonic discrimination diagrams using immobile HFS Nb and Y elements. And the trachyte shows typical signatures of A-type volcanic rocks with high Ga abundance and is classified as A1-type volcanic rocks rich in Nb. The geochemical signatures suggest that the trachyte was produced by the differentiation of mantle-derived magmatism at the continental rift in extensional setting subsequent to a major collision during the Permo-Triassic Songrim orogeny. The results provide robust evodence to consider the Imjingang belt as an extension of the the Qinling-Dabie-Sulu belt between the North and South China blocks.

• Korean Journal of Remote Sensing
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• v.22 no.6
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• pp.621-626
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• 2006

Today's commercial high resolution satellite imagery such as IKONOS and QuickBird, offers the potential to extract useful spatial information for geographical database construction and GIS applications. Extraction of 3D building information from high resolution satellite imagery is one of the most active research topics. There have been many previous works to extract 3D information based on stereo analysis, including sensor modelling. Practically, it is not easy to obtain stereo high resolution satellite images. On single image performance, most studies applied the roof-bottom points or shadow length extracted manually to sensor models with DEM. It is not suitable to apply these algorithms for dense buildings. We aim to extract 3D building information from a single satellite image in a simple and practical way. To measure as many buildings as possible, in this paper, we suggested a new way to extract building height by triangular vector structure that consists of a building bottom point, its corresponding roof point and a shadow end point. The proposed method could increase the number of measurable building, and decrease the digitizing error and the computation efficiency.

• Journal of Advanced Marine Engineering and Technology
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• v.36 no.4
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• pp.490-496
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• 2012

The main object of this research is to minimize the shock effects which frequently result in fatal damage in offshore wind turbine on impact of barge. The collision between offshore wind turbine and barge is generally a complex problem and it is often impractical to perform rigorous finite element analyses to include all effects and sequences during the collision. On applying the impact force of a barge to the offshore wind turbine, the maximum acceleration, internal energy, and plastic strain are calculated for each load case using the finite element method. A parametric study is conducted with the experimental data in terms of the velocity of barge, thickness of the offshore wind turbine, and thickness and Mooney-Rivlin coefficient of the rubber fender. Through the analysis proposed in this study, it is possible to determine the proper size and material properties of the rubber fender and the optimal moving conditions of barge.

• Journal of the Korean Institute of Intelligent Systems
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• v.19 no.2
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• pp.230-235
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• 2009

This paper describes an automatic finite element mesh generation for finite element analysis of three-dimensional structures. It is consisting of fuzzy knowledge processing, bubble meshing and solid geometry modeler. This novel mesh generation process consists of three subprocesses: (a) definition of geometric model, i.e. analysis model, (b) generation of bubbles, and (c) generation of elements. One of commercial solid modelers is employed for three-dimensional solid structures. Bubble is generated if its distance from existing bubble points is similar to the bubble spacing function at the point. The bubble spacing function is well controlled by the fuzzy knowledge processing. The Delaunay method is introduced as a basic tool for element generation. Automatic generation of finite element for three-dimensional solid structures holds great benefits for analyses. Practical performances of the present system are demonstrated through several mesh generations for 3D geometry.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.1
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• pp.1-6
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• 2013

Three Surface cracks are among the more common flaws in aircraft and pressure vessel components. Accurate stress intensity analyses and crack growth rate data of surface-cracked components are needed for reliable prediction of their fatigue life and fracture strengths. Three Dimensional finite element method (FEM) was used to obtain the stress intensity factor for surface cracks existing in structures. A geometry model, i.e. a solid containing one or several 3D cracks is defined. Nodes are generated by bucket method, and quadratic tetrahedral solid elements are generated by the Delaunay triangulation techniques. To examine accuracy and efficiency of the present system, the stress intensity factor for a semi-elliptical surface crack in cylindrical structures subjected to pressure is calculated. Analysis results by present system showed good agreement with those by ASME equation and Raju-Newman's equation.

• Journal of the Korea institute for structural maintenance and inspection
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• v.16 no.1
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• pp.89-98
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• 2012

A steel wire-integrated deck plate that welds integrated triangle truss steel wires on a galvanized steel sheet is developed to reduce construction costs of slabs or formworks such as shores and supports, and it is already widely applied in many construction fields. In this research, experimental tests for 14 full scale specimens, which are in the same field conditions, are conducted on several parameters such as the diameter of top, bottom and lattice steel wire, cutting methods of ends. According to the result, changes in final destruction types of the test bodies and cutting methods of ends didn't affect structural performance of test specimens, and for a 4.0m-span test specimen, there was no big problems in using bottom bar D7 or D8.

• The Bulletin of The Korean Astronomical Society
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• v.40 no.1
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• pp.45.2-45.2
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• 2015

우리는 최근 현대천문학의 가장 오래된 난제로 우리은하 헤일로의 형성과 깊은 관련이 있는 구상성단계의 오스터호프 이분법이 다중항성종족 패러다임 하에서 76년 만에 완벽히 규명되는 것을 발견하였다. 또한 이 연구의 기본 개념을 우리은하 벌지에 적용한 결과, 기존 국제학계의 이론과 완전히 다른 벌지의 형성기원에 대한 새로운 해석에 도달하였다. 우리은하의 벌지에 대한 대규모 측광 서베이 분석으로부터 double red clumps가 있다는 것이 2010년에 발견되었고, 이는 디스크와 바 불안정에 기인하는 은하중심부 X-shape 구조의 증거로 널리 받아들여지고 있다. 그러나 우리는 이와 같은 국제학계의 해석이 수평계열성의 항성진화이론을 간과한데서 비롯된 허구일 가능성을 제시하고자 한다. 우리의 모델에 의하면 관측된 double red clumps는 Omega Cen을 포함하는 대다수의 구상성단에서 발견되는 것과 동일한 헬륨함량이 증가된 2세대 별들(G2)에 의한 효과이다. 우리은하 벌지에 위치한 Terzan 5 구상성단처럼, 중원소함량이 높은 벌지에서는 G2에 해당하는 수평계열성들이 광도가 약 0.5등급 더 밝은 red clump 위치에 놓이게 되어 자연스럽게 double red clumps를 형성하게 된다. 앞으로 우리의 새로운 해석이 Gaia에 의한 삼각시차 거리결정으로 확인된다면, 이는 우리은하 벌지를 이루는 대부분의 별들이 Terzan 5와 같은 윈시 빌딩블럭들의 합병과 붕괴에 의해 형성되었다는 것을 암시하여, 우리은하는 물론, 조기형은하의 형성기원 연구에 큰 전환점이 될 것으로 기대한다.

• 한국신재생에너지학회:학술대회논문집
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• 2010.11a
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• pp.190.1-190.1
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• 2010

풍력자원평가를 위해 풍력단지 개발대상지의 국지풍황 대표지점에 설치하는 풍황탑(met-tower 또는 풍황마스트; met-mast)은 모노폴(monopole), 삼각단면 트러스 또는 사각단면 트러스 구조를 갖는다. 풍향계 및 풍속계는 이러한 지지구조물에 의한 풍속의 교란 또는 차폐영향을 최소화하기 위하여 긴 붐(boom)의 끝단에 설치되지만 계측기가 풍황탑의 직후방 후류영역에 놓이게 될 경우 차폐영향을 완전히 피하기는 어렵다. 저자들의 선행연구에 따르면 풍황탑 차폐영향은 평균풍력밀도의 경우 2.5% 이상의 오차를 유발할 수 있으므로 풍력자원평가 시 필히 고려되어야 할 불확도 요인인 것이다. 이에 한국에너지기술연구원에서는 풍황탑 주위의 대기유동장을 전산유동해석을 이용하여 차폐영향의 정도를 정량적으로 수치모사함으로써 이를 보정하는 기술을 개발한 바 있다(현재 특허심사 중). KIER-$ShadeFree^{TM}$는 이 특허기술을 프로그램화 한 것으로, 시범적으로 다수의 풍황탑 풍력자원 측정자료에 적용하여 상당한 보정효과에 의한 풍력자원평가의 정확도 향상효과를 볼 수 있었다.

• Journal of the Korea Computer Graphics Society
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• v.14 no.1
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• pp.27-33
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• 2008

Mobile systems have relatively limited resources such as low memory, slow CPU, or low power comparing to desktop systems. In this paper, we present a new 3D mesh connectivity coding algorithm especially optimized for mobile systems(i.e., mobile phones). By using adaptive octree data structure for vertex positions, a new distance-based connectivity coding is proposed. Our algorithm uses fixed point arithmetic and minimizes dynamic memory allocation, appropriate for mobile systems. We also demonstrate test data to show the utility of our mobile 3D mesh codec.