• International Journal of CAD/CAM
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• 제6권1호
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• pp.117-123
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• 2006

Recently with the development of 3D modeling and digitizing tools, more and more models have been created, which leads to the necessity of the technique of 3D mode retrieval system. In this paper we investigate a new method for 3D model retrieval based on orthogonal projections. We assume that 3D models are composed of trigonal meshes. Algorithms process first by a normalization step in which the 3D models are transformed into the canonical coordinates. Then each model is orthogonally projected onto six surfaces of the projected cube which contains it. A following step is feature extraction of the projected images which is done by Moment Invariants and Polar Radius Fourier Transform. The feature vector of each 3D model is composed of the features extracted from projected images with different weights. Our System validates that this means can distinguish 3D models effectively. Experiments show that our method performs quit well.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2004년도 ICEIC The International Conference on Electronics Informations and Communications
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• pp.361-364
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• 2004

This paper describes an automatic 3D models generation algorithm based on 2D silhouette images, using X-ray camera without camera parameters. The algorithm takes a multi steps process approach. First, a series of 2D silhouette images is captured from different directions of object and then converted to binary images. An octree data structure is constructed for voxel-based representation of object. An estimate 3D volume of object can be reconstructed by intersecting voxels and the 2D silhouettes. The marching cube algorithm is applied to get triangle mesh representing of the obtained 3D model for rendering.

• 한국분말재료학회지
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• 제15권5호
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• pp.371-377
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• 2008

This paper deals with the phase analysis of $MgB_2$ bulk using spark plasma sintering process after ball milling. Mg and amorphous B powders were used as raw materials, and milled by planetary-mill for 9 hours at argon atmosphere. In order to confirm formation of $MgB_2$ phase, DTA and XRD were used. The milled powders were fabricated to $MgB_2$ bulk at the various temperatures by Spark Plasma Sintering. The fabricated $MgB_2$ bulk was evaluated with XRD, EDS, FE-SEM and PPMS. In the DTA result, reaction on formation of $MgB_2$ phase started at $340^{\circ}C$. This means that ball milling process improves reactivity on formation of $MgB_2$ phase. The $MgB_2$ MgO and FeB phases were characterized from XRD result. MgO and FeB were undesirable phases which affect formation of $MgB_2$ phase, and it's distribution could be confirmed from EDS mapping result. Spark Plasma Sintered sample for 5 min at $700^{\circ}C$ was relatively densified and it's density and transition temperature showing super conducting property were $1.87\;g/cm^3$ and 21K.

• 전기학회논문지
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• 제57권11호
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• pp.1916-1921
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• 2008

This paper presents the temporal classification method based on data mining techniques for discovering knowledge from measured load patterns of distribution transformers. Since the power load patterns have time-varying characteristics and very different patterns according to the hour, time, day and week and so on, it gives rise to the uninformative results if only traditional data mining is used. Therefore, we propose a temporal classification rule for analyzing and forecasting transformer load patterns. The main tasks include the load pattern mining framework and the calendar-based expression using temporal association rule and 3-dimensional cube mining to discover load patterns in multiple time granularities.

• Wind and Structures
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• 제5권2_3_4호
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• pp.177-192
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• 2002

Computation solutions for the flow around a cube, which were generated as part of the Computational Wind Engineering 2000 Conference Competition, are compared with full-scale measurements. The three solutions shown all use the RANS approach to predict mean flow fields. The major differences appear to be related to the use of the standard $k-{\varepsilon}$, the MMK $k-{\varepsilon}$ and the RNG $k-{\varepsilon}$ turbulence models. The inlet conditions chosen by the three modellers illustrate one of the dilemmas faced in computational wind engineering. While all modeller matched the inlet velocity profile to the full-scale profile, only one of the modellers chose to match the full-scale turbulence data. This approach led to a boundary layer that was not in equilibrium. The approach taken by the other modeller was to specify lower inlet turbulent kinetic energy level, which are more consistent with the turbulence models chosen and lead to a homogeneous boundary layer. For the $0^{\circ}$ case, wind normal to one face of the cube, it is shown that the RNG solution is closest to the full-scale data. This result appears to be associated with the RNG solution showing the correct flow separation and reattachment on the roof. The other solutions show either excessive separation (MMK) or no separation at all (K-E). For the $45^{\circ}$ case the three solutions are fairly similar. None of them correctly predicting the high suctions along the windward edges of the roof. In general the velocity components are more accurately predicted than the pressures. However in all cases the turbulence levels are poorly matched, with all of the solutions failing to match the high turbulence levels measured around the edges of separated flows. Although all of the computational solutions have deficiencies, the variability of results is shown to be similar to that which has been obtained with a similar comparative wind tunnel study. This suggests that the computational solutions are only slightly less reliable than the wind tunnel.

• 한국게임학회 논문지
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• 제19권6호
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• pp.49-60
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• 2019

Interior Mapping은 효율적으로 그래픽 리소스를 최적화하는 방법들 중에 하나로 사용되어왔다. 본 논문에서는 보편화 된 게임엔진인 Unreal Engine 4를 활용하여 Interior Mapping을 적용했을 시 3D 게임 내의 성능 변화를 검증하기 위해 실제 모델링과 Interior Mapping의 렌더링 속도(FPS), 폴리곤 개수, 쉐이더 복잡도, 각각의 리소스 용량을 비교하였다. 또한, 효율적인 기술의 적용을 위해 큐브 맵 텍스처의 해상도와 세부 정보에 따른 성능 차이를 검증하였다.

• 전자공학회논문지
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• 제50권10호
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• pp.150-161
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• 2013

본 논문에서는 다수의 카메라들을 이용하여 3차원 공간상에 있는 물체에 대한 다중 시점 영상들을 획득하고, 그 영상들로부터 해당 3차원 물체에 대한 기하학적인 형상 및 질감 정보를 추정하여, 그 물체에 대한 고해상도 3차원 콘텐츠를 효율적으로 제작하는 새로운 시스템을 제안한다. 지금까지 다양한 다중 시점 영상 기반 3차원 객체 복원 시스템들이 제안되었지만 다중 시점 기반 3차원 객체 복원이 많은 메모리와 계산량을 필요로 하기 때문에 고해상도의 3차원 콘텐츠를 얻는 데에는 어려움이 있었다. 3차원 복원에 필요한 계산량 및 메모리량을 줄이기 위해 제안 시스템은 객체의 다중 시점을 촬영한 영상 내에서 객체가 존재할 수 있는 영역을 사전에 설정하여 객체 윤곽선 추출 과정을 빠르게 수행한다. 그리고 체인코드를 활용하여 실루엣 영상을 표현하고 3차원-2차원 투영 및 역투영 관계를 1차원 호모그래피를 통해 표현하여 객체의 비주얼 헐을 빠르게 계산한다. 복원된 3차원 객체의 기하정보는 3차원 선분 기반의 표현 기법인 DoCube를 활용하여 적은 데이터양으로 표현하였으며, 3차원 메시 생성 및 텍스쳐 맵핑을 수행하여 최종적인 3차원 객체를 생성한다. 실험 결과 제안 시스템이 $800{\times}800{\times}800$ 해상도의 3차원 객체 복원을 프레임 당 2.2초에 수행하는 것을 확인하였다.

• 대한임베디드공학회논문지
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• 제12권4호
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• pp.193-204
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• 2017

Various 3D-stacked DRAMs have been proposed to overcome the memory wall problem. Hybrid Memory Cube (HMC) is a true 3D-stacked DRAM with stacked DRAM layers on top of a logic layer. The logic die is mainly used to implement a memory controller for HMC, and it is connected through a high speed serial link called SerDes with a host that is either a processor or another HMC. In HMC, the serial link is crucial for both performance and power consumption. Therefore, it is important that the link is configured properly so that the required performance should be satisfied while the power consumption is minimized. In this paper, we propose a HMC system model included the high speed serial link to estimate performance accurately. Since the link modeling strictly follows the link flow control mechanism defined in the HMC spec, the actual HMC performance can be estimated accurately with respect to each link configuration. Various simulations are conducted in order to deduce the correlation between the HMC performance and the link configuration with regard to memory utilization. It is confirmed that there is a strong correlation between the achievable maximum performance of HMC and the link configuration in terms of both bandwidth and latency. Therefore, it is possible to find the best link configuration when the required HMC performance is known in advance, and finding the best configuration will lead to significant power saving while the performance requirement is satisfied.

• 정보과학회 논문지
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• 제43권4호
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• pp.419-429
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• 2016

최근 관상동맥 영역화 결과로부터 삼차원 표면 모델을 생성함으로써 혈관 구조적 정보의 렌더링 효율성의 증대뿐만 아니라 전산유체역학를 이용한 혈류 역학 시뮬레이션을 통해 혈류분획예비력과 같은 생리적 정보들을 획득하는 연구들이 활발히 진행되고 있다. 본 논문에서는 혈관 영역화 과정에서 획득한 혈관 구조 정보를 입력 데이터로 사용하여 관상동맥의 삼차원 삼각 표면 메쉬 모델을 생성하는 방법을 제안한다. 관상동맥 영역화 결과로부터 삼각형 표면 메쉬 모델을 만드는 방법으로는 Marching cube 알고리즘에 기반한 방법들이 있지만 이산적인 영상 공간에서 수행되는 알고리즘으로 가늘고 다양한 굴곡을 갖는 혈관 경계를 표현하기 힘들다. 제안된 방법은 관상동맥 영역화 과정에서 추정한 혈관 중심좌표와 법선 벡터 그리고 직경 정보를 이용하여 기존 방법들보다 정교하게 단일 혈관 가닥들에 대한 삼각 표면 메쉬들을 생성하고 분기가 일어나 중첩되는 메쉬들은 메쉬 병합 기법을 사용하여 처리함으로써 통합된 관상동맥 메쉬를 생성한다.

• 대한기계학회논문집B
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• 제36권6호
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• pp.669-674
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• 2012

최근에 준공된 디큐브시티는 사무용, 상업용, 숙박용 및 관람집회용 등 4개의 시설이 공존하는 복합건물이다. 이 건물에는 필요로 하는 전기와 증기, 온수 및 냉수를 공급하기 위해 구역형 에너지공급시스템(Community energy supply system)이 설치되었다. 다양한 건물설비를 효과적으로 운영하기 위해 건물에너지관리시스템(Building energy management system)의 설치를 검토하고 있다. 본 연구에서는 3개의 열병합발전시스템을 비롯하여 7대의 증기보일러, 2대의 중온수보일러와 2대의 흡수식냉동기 및 4대의 터보냉동기 등으로 구성되는 구역형 에너지공급시스템의 최적 운전 및 설계방법을 검토하였다. 결과로서 에너지 수요변화에 따른 구역형 에너지공급시스템의 최적 운전방법과 계절적 운전조건의 변화가 시스템의 경제성에 미치는 영향을 규명하였다. 또 시설별 규모에 따라 결정되는 에너지 수요가 건물 전체의 에너지 소비에 미치는 영향도 분석하였다.