• Proceedings of the Korean Society of Broadcast Engineers Conference
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• fall
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• pp.23-26
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• 2021

본 논문에서는 동적 포인트 클라우드 압축 표준인 V-PCC 을 기반으로 고밀도 동적 메쉬 데이터를 압축하는 방법을 제안한다. 제안하는 방법은 정점마다 색상 값을 갖는 고밀도 동적 메쉬 데이터 압축 구조로 정점마다 갖는 위치 정보와 색상정보는 V-PCC 를 통해 압축을 수행하고 정점들의 연결정보는 TFAN 기술을 통해 압축을 수행한다. 이때 V-PCC 를 통해 복원된 정점의 순서와 TFAN 을 통해 복원된 연결정보의 정점 인덱스 정보는 복원 후 변경되어 둘 사이를 매핑 해주기 위한 방법이 필요하다. 본 논문에서는 부호화기에서 3D morton 코드 기반으로 원본 정점과 V-PCC 를 통해 복원된 정점을 효과적으로 매핑하는 방법을 제안한다. 제안하는 메쉬 압축 방법은 기존 MPEG-4 의정적 메쉬 데이터 압축 표준인 SC3DMC 와의 비교를 통해 V-PCC 기반 동적 메쉬 데이터 압축의 효율성을 보인다.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.30 no.5
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• pp.381-387
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• 2017

Fiber-reinforced composites not only have a direction of thermal expansion coefficient, but also inevitably suffer thermal stress effects due to the difference between the manufacturing process temperature and the actual use temperature. The damage caused by thermal stress is more prominent in the case of thick composite laminates, which are increasingly applied in the aerospace industry, and have a great influence on the mechanical function and fracture strength of the laminates. In this study, the dimensional reduction and thermal stress recovery theory of composite beam structure having high slenderness ratio is introduced and show the efficiency and accuracy of the thermal stress comparison results between the 3-D finite element model and the dimension reduction beam model. Efficient recovery analysis study will be introduced by reconstructing the thermal stress of the composite beam section applied to the thermal environment by constructing the dimensional reduction modeling and recovery relations.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2014.06a
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• pp.79-80
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• 2014

본 논문에서는 다방향 패턴을 이용한 구조광(structured light)방식의 3차원 스캔 기법을 적용하여 3차원 스캐너의 3차원 형상 취득의 정밀도를 높이는 방법을 제안한다. 기존의 단방향 패턴을 이용한 3차원 구조광 방식의 스캔 기법으로 3차원 형상을 취득하는 경우, 스캔 대상 표면의 법선벡터가 패턴의 방향과 수평 할수록 부정확한 형상이 복원된다. 본 논문에서는 스캔 대상의 경사면에 따른 법선 벡터(normal vector) 검출 및 검출된 벡터를 통한 최적의 패턴 방향 선출(quantization), 그리고 각 화소의 최적의 패턴방향을 이용한 선별적인 구조광 방식의 3차원 스캔 기법을 통하여 3차원 형상 취득의 정확성을 높이는 기법을 제안한다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.43 no.10
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• pp.920-927
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• 2015

In this paper, numerical results of sectional analysis and stress recovery were compared with the results of VABS through the blade analysis library. The results of recovery analysis for one-dimensional model including the stiffness matrix is compared with the calculated three-dimensional stress results of three-dimensionial FEM based on the principle of virtual work. We discuss the configuration of the blade analysis library and compare verifications of numerical analysis results of VABS. Blade analysis library through dimensional reduction and stress recovery is intended to be utilized in conjunction with pre- and post-processing of the analysis program of the composite blade, high-altitude uav's wing, wind blades and tilt rotor blade.

• Journal of the Korea Computer Graphics Society
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• v.7 no.2
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• pp.1-9
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• 2001

본 논문은 여러 장의 이미지로부터 삼차원 모델을 빠르게 복원하기 위한 다각형 기반 Space Carving 알고리즘을 제안한다. 본 논문에서 제안하는 알고리즘은 기존의 복셀 carving 연산에 다각형 carving 연산을 추가하여 기존 복셀 carving 기법의 단점인 렌더링 품질의 저하와 느린 렌더링 속도 문제를 보완하였다. 따라서 복원된 모델은 다각형 구조를 가지며, 이로부터 텍스쳐 매핑을 이용한 빠른 속도의 고품질 렌더링 기법이 가능해진다. 또한 다각형 carving 후잉여 데이터를 삭제함으로써 복원된 모델의 품질 저하없이 메모리를 줄이고, 더욱 빠른 렌더링을 가능하게 한다.

• Geophysics and Geophysical Exploration
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• v.11 no.4
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• pp.286-301
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• 2008

When magnetotelluric (MT) data are obtained in vicinity of the coast, the sea can distort observed MT responses, especially those of deep part of subsurface. We introduce an iterative method to correct the sea effect, based on the previous topographic correction method which removes the distortions due to topographic changes in seafloor MT data. The method first corrects the sea effect in observed MT impedance, and then inverts corrected responses in a model space without the sea. Due to mutual coupling between sea and subsurface structure, the correction and inversion steps are iterated until changes in each result become negligible. The method is validated for 1-D and 2-D structure using synthetic MT data produced by 3-D forward modeling including surrounding seas. In all cases, the method closely recovers the given structure after a few iterations. To test the applicability of the proposed method to field data, we generate synthetic MT data for the Jeju Island whose 1-D conductivity structure is well known, using 3-D forward modeling. The distortions due to the surrounding sea start to appear below the frequency about 1 Hz, and are relatively severe in the electrical field perpendicular to the coastline because of the location of the observation sites. The proposed method successfully eliminates the sea effect after three iterations, and both 1-D and 2-D inversion of corrected responses closely recover the given subsurface structure of the Jeju Island model.

• Ecology and Resilient Infrastructure
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• v.6 no.1
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• pp.1-11
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• 2019

This study performed the impact of ecological waterway on fish community in a reach of the Dal River, Korea. Fish monitoring revealed that 9 fish species are dominant, namely Zacco platypus, Coreoleuciscus splendidus, Zacco koreanus, Pungtungia herzi, Acheilognathus yamatsutae, Rhinogobius brunneus, Tanakia signifer, Gobiobotia macrocephala, and Pseudopungtungia tenuicorpus, and account for 95% of the total fish community. The River2D model was used for the computation of the flow and the HSI model for the habitat simulation. The restoration of the waterway performed through the small dam removal, the formation of the pool-riffle structure, and the change of the bed elevation and width. Simulation results indicated that the restoration of the ecological waterway effects significantly increased by about 16% for the WUA (Weighted Usable Area) of the total fish community in optimal ecological flow conditions ($Q=7.0m^3/s$). The restoration of the ecological waterway is more advantageous to fish community.

• Journal of Korea Multimedia Society
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• v.13 no.2
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• pp.332-340
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• 2010

This paper presents the digitally implementable methods to preserve and restore the traditional wooden buildings, which are the typical "Korean Cultural Contents," by using computer and multimedia technologies. We first define the meaning of the digital implementation of Korean traditional wooden buildings and important points to be considered. In addition, we present the steps and methods for implementation. Furthermore, we considered wooden materials, structures and Danchung (patterns of paintings on the wooden pieces) in implementing of Gongpo (wooden structure system) for both Geunjeongjeon of Gyeongbok Palace and Injungjeon of Changduk Palace by using the presented methods. We present the mechanical method to digitally implement wooden buildings by using numerical ratios of Gongpo. The other advantage of this paper over the other studies, which focus on implementation of exterior of wooden buildings, is presenting the methods how to show the complicated relations of inner parts in Korea wooden buildings. Thus, it can be practically used in preserving and restoring Korean traditional wooden buildings.

• Proceedings of the IEEK Conference
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• 2003.11a
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• pp.183-186
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• 2003

A vision sensor should be calibrated prior to infer a Euclidian shape reconstruction. A point to point calibration. also referred to as a hard calibration, estimates calibration parameters by means of a set of 3D to 2D point pairs. We proposed a new method for determining a set of 3D to 2D pairs for the structured light hard calibration. It is simply determined based on epipolar geometry between camera image plane and projector plane, and a projector calibrating grid pattern. The projector calibration is divided two stages; world 3D data acquisition Stage and corresponding 2D data acquisition stage. After 3D data points are derived using cross ratio, corresponding 2D point in the projector plane can be determined by the fundamental matrix and horizontal grid ID of a projector calibrating pattern. Euclidian reconstruction can be achieved by linear triangulation. and experimental results from simulation are presented.

• Journal of architectural history
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• v.19 no.5
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• pp.25-47
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• 2010

The purpose of this study is to reconstruct the wooden frame structure of Buddhist temple, Kumdang in Youngamsaji which assumed to be built in the 9th century of Unified Silla Dynasty. The remaining site of Kumdang in Youngamsaji is investigated thoroughly with a particular attention to bay size and column distribution. The five ancient Buddhist temples which were built in the same period also have the same frame type as Youngamsaji Kumdang. These five ancient Buddhist temples and Kumdang in Youngamsaji are meticulously investigated in terms of their bay sizes and measuring modules. The framework schema is devised as a conceptual tool to conjecture wooden frame structures of Buddhist temple. A theoretical differentiation between frame type and frame structure is attempted to formulated a wooden frame structure as a stepping-stone for the reconstruction of traditional wooden building. The wooden frame structure of 9C Kumdang in Youngamsaji mainly follows the oldest Korean wooden pavilion, Muryangsujeon in Busuk temple, with a hip and gable roof. The wooden frame structure of 9C Kumdang in Youngamsaji is reconstructed through 3D computer modeling to such an extent that every wooden components of the structure can be 3D printed. The reconstruction also takes reference from the Cai-Fen system in Yingzao Fashi.