• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2005년도 Proceedings of ISRS 2005
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• pp.321-324
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• 2005

In these days, the management and visualization of 3D geo-spatial information is regarded as one of an important issue in GiS and remote sensing fields. 3D GIS is considered with the database issues such as handling and managing of 3D geometry/topology attributes, whereas 3D visualization is basically concerned with 3D computer graphics. This study focused on the design and implementation for the OpenGL API-based rendering system for the complex types of 3D geo-spatial features. In this approach 3D features can be separately processed with the functions of authoring and manipulation of terrain segments, building segments, road segments, and other geo-based things with texture mapping. Using this implementation, it is possible to the generation of an integrated scene with these complex types of 3D features. This integrated rendering system based on the feature-based 3D-GIS model can be extended and effectively applied to urban environment analysis, 3D virtual simulation and fly-by navigation in urban planning. Furthermore, we expect that 3D-GIS visualization application based on OpenGL API can be easily extended into a real-time mobile 3D-GIS system, soon after the release of OpenGLIES which stands for OpenGL for embedded system, though this topic is beyond the scope of this implementation.

• 한국공간정보시스템학회 논문지
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• 제9권3호
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• pp.17-24
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• 2007

소음문제는 대도시 환경문제 중 주요한 문제 중의 하나로 관심이 높으며, 도시계획과 설계분야에 소음지도의 활용이 증가하고 있는 추세이다. 그러나, 기존의 2D 소음지도는 주로 평면적인 소음분포만을 나타내고 있어 최근 고층화, 대형화 되어가는 건물의 각 공간에 대한 미시적 소음분석 및 시각화에는 한계를 갖고 있다. 따라서 본 연구에서는 평면적이고 지역적인 소음분포의 표현에만 머무르고 있는 기존 소음지도의 한계점을 인지하고 소음의 수직적인 분포를 고려하여 공간단위의 소음분석 및 시각화를 위한 데이터모델을 제시하였다. GIS의 토폴로지 구조를 3차원으로 확장함으로써 3차원 공간분석 및 공간단위 시각화가 가능한 3차원 GIS 데이터모델을 제안하고 이를 3차원 소음정보시스템에 적용하고자 하였다. 간단한 3차원 소음정보시스템을 구축하여 3차원 공간질의, 시간대별 3차원 소음시각화, 방음벽의 높이에 따른 소음의 변화량을 시뮬레이션하고 각각의 경우 소음노출가구 및 인구를 정량적으로 산정함으로써 도시계획 및 설계분야에서의 활용가능성을 예시하였다.

• 한국전자파학회논문지
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• 제12권1호
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• pp.65-70
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• 2001

본 연구에서는 CDMA 단말기요 Receiver MMIC를 설계하였다. 전체회로는 저잡음 증폭기, 하향 주파수 혼합기, 중간주파수 증폭기 그리고 바이어스 회로로 구성된다. 바이어스회로는 문턱전압과 전원접압의 변화에 대해 보상동작을 한다. 제안된 토폴리지는 높은 선형성과 저잡음 특성을 가진다. 설계결과는 다음과 같다. 전체 변환이득은 28.5 dB, 저잡음 증폭기의 압력은 IP3는 8 dBM, 하향주파수 혼합기의 압력 IP3는 0 dBm 이며 전체회로의 소모전류는 22.1 mA이다.

• ETRI Journal
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• 제33권3호
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• pp.462-465
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• 2011

A millimeter-wave (mm-wave) high-linear low-noise amplifier (LNA) is presented using a 0.18 ${\mu}m$ standard CMOS process. To improve the linearity of mm-wave LNAs, we adopted the multiple-gate transistor (MGTR) topology used in the low frequency range. By using an MGTR having a different gate-source bias at the last stage of LNAs, third-order input intercept point (IIP3) and 1-dB gain compression point ($P_{1dB}$) increase by 4.85 dBm and 4 dBm, respectively, without noise figure (NF) degradation. At 33 GHz, the proposed LNAs represent 9.5 dB gain, 7.13 dB NF, and 6.25 dBm IIP3.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2004년도 ICEIC The International Conference on Electronics Informations and Communications
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• pp.137-142
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• 2004

In this paper, we propose a new scheme for geometry coding of three-dimensional (3-D) mesh models using a fixed spectral basis. In order to code the mesh geometry information, we generate a fixed spectral basis using the dual graph derived from the 3-D mesh topology. After we partition a 3-D mesh model into several independent sub-meshes to reduce coding complexity, the mesh geometry information is projected onto the generated orthonormal bases which are the eigenvectors of the Laplacian matrix of the 3-D mesh. Finally, spectral coefficients are coded by a quantizer and a variable length coder. The proposed scheme can not only overcome difficulty of generating a fixed spectral basis, but also reduce coding complexity. Moreover, we can provide an efficient multi-resolution representation of 3-D meshes.

• 한국전산구조공학회논문집
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• 제31권6호
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• pp.353-358
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• 2018

본 연구는 전기자동차 충전시스템에서 전력변환장치의 경량화를 위한 최적화 분석프로세스에 대한 내용을 서술하였다. 최적화 설계는 재료 물성치에 대한 설계민감도와 수학적 최적화를 결합하여 주어진 재료량 제한조건 하에 최적의 재료분포를 찾는 설계기법으로 위상의 고정화, 자유도가 묶이는 문제 등을 해결할 수 있는 위상 최적화방법을 사용하였으며, 위상 최적화 방법 중 비교적 수식화가 간단하고 수렴성이 좋은 SIMP법(solid isotropic material with penalization)에 의해 경량화 설계를 수행하였다. 경량화 설계는 3단계의 절차로 구성하였으며, 첫 번째 단계로 전력변환장치의 기본 설계에 대한 유한요소모델을 구성하고, 하중에 대한 정적해석을 수행하였다. 두 번째 단계로 정적해석 결과에 대해 등방성 재료의 강성계수를 적용한 밀도법을 이용하여 위상 최적화를 수행하여 경량화를 위한 최적 형상을 도출하였다. 세 번째 단계로 최적 형상에 대해 차량 탑재 부품의 충격시험기준에 만족하는 반정현파 펄스형태 충격하중을 인가하여 충격해석을 수행하였다. 위상 최적화단계에서 사용 환경조건으로 설계영역 정의는 마운팅 브래킷 영역으로 제한하였으며, 마운팅 브래킷의 설계 최적화를 통해 최종적으로 기본설계대비 20%이상의 경량화가 가능한 설계기술을 확보하였다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제3권6호
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• pp.667-681
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• 2009

We describe a method to decompose a cube with trilinear interpolation into a collection of tetrahedra with linear interpolation, where the isosurface topology is preserved for all isovalues during decomposition. Visualization algorithms that require input scalar data to be defined on a tetrahedral grid can utilize our method to process 3D rectilinear data with topological correctness. As one of many possible examples, we apply the decomposition method to topologically accurate tetrahedral mesh extraction of an interval volume from trilinear volumetric imaging data. The topological correctness of the resulting mesh can be critical for accurate simulation and visualization.

• International Journal of CAD/CAM
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• 제5권1호
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• pp.59-68
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• 2005

Euclidean Voronoi diagram of spheres in 3-dimensional space has not been explored as much as it deserves even though it has significant potential impacts on diverse applications in both science and engineering. In addition, studies on the data structure for its topology have not been reported yet. Presented in this, paper is the topological representation for Euclidean Voronoi diagram of spheres which is a typical non-manifold model. The proposed representation is a variation of radial edge data structure capable of dealing with the topological characteristics of Euclidean Voronoi diagram of spheres distinguished from those of a general non-manifold model and Euclidean Voronoi diagram of points. Various topological queries for the spatial reasoning on the representation are also presented as a sequence of adjacency relationships among topological entities. The time and storage complexities of the proposed representation are analyzed.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• 제15권3호
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• pp.161-175
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• 2011

An n-string tangle is a three dimensional ball with n strings properly embedded in it. A tangle model of a DNA-protein complex is first introduced by C. Ernst and D. Sumners in 1980's. They assumed the protein bound DNA as strings and the protein as a three dimensional ball. By using a tangle analysis, one can predict the topology of DNA within the complex. S.Kim and I. Darcy developed the biologically reasonable 4-string tangle equations and decided a solution tangle, called R-standard tangle. The author discussed more about the simple solution tangles of the equations and found a generalized R-standard tangle solution.

• Journal of Power Electronics
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• 제8권3호
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• pp.259-267
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• 2008

Power quality improvement in a three-phase four-wire system is achieved using a new topology of DSTATCOM (distribution static compensator) consisting of a star/delta transformer with a tertiary winding and a three-leg VSC (voltage source converter). This new topology of DSTATCOM is proposed for power factor correction or voltage regulation along with harmonic elimination, load balancing and neutral current compensation. A tertiary winding is introduced in each phase for a delta connected secondary in addition to the star-star windings and this delta connected winding is responsible for neutral current compensation. The dynamic performance of the proposed DSTATCOM system is demonstrated using MATLAB with its Simulink and Power System Blockset (PSB) toolboxes under varying loads. The capacitor supported DC bus of the DSTATCOM is regulated to the reference voltage under varying loads.