• 한국지구물리탐사학회:학술대회논문집
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• 2006.06a
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• pp.233-237
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• 2006

3D travel time tomography was conducted to characterize the subsuface structure in the valley area. In this study, an area($200m{\times}200m$), where borehole informations were available to aid in the interpretation, was covered with wide source/receiver coverage. In data acquisition, both hole to hole and reverse VSP array was employed. For the inversion, 3D seismic traveltime tomography algorithm based on Fresnel volume was implemented. When compared 3D velocity cube with the geological survey and drilling logs, both results were matched well. From this, we concluded that 3D seismic travel time tomography has enough potential to the field application.

• Geotechnical Engineering
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• v.5 no.3
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• pp.19-28
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• 1989

This study has been carried out as a fundamental course for the analysis of the constitutive- equation for the materials like sands being hardened during Ehear. For this aim, experimentall tests with variable stress paths for the concrete material are performed using the cubical multi- axial test in which the three principle stresses are arbitrarily controlled. Stress-strain behaviors. and strength characteristics are suggested in octahedral planes. Various tests such as HC, CTC, . TC, 55 are performed. The main results summarized are as follows; 1. The order of strength from the largest to the smallest is CTC, TC, SS, and TE test. 2. The octahedral Ehear strength of concrete specimens is dependent upon the stress path(8) 3. There is a direct relation between strength and confining pressure. 4. The ultimate envelopes in the octahedral planes are non-circular-cone shaped. 5. Any ultimate criteria used to predict the strength behavior of concrete must include thin effect of the tensile stresses.

• Tunnel and Underground Space
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• v.18 no.4
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• pp.263-271
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• 2008

3D seismic tomography technique was assessed for applicability of developed 3D tomography algorithm based on Fresnel volume in the dam-planned area. Reconstructed 3D tomogram based on Fresnel volume and Fast Marching Method(FMM) reveals similar velocity structure to the other geotechnical survey results. With the correlation analysis between RMR data and seismic velocity information, it could provide reliable information of rock mass rate. The applicability of 3D seismic tomography was verified in this study. It would be expected to apply 3D tomography with new developed first arrival calculation and inversion algorithm to the engineering field economically.

• Proceedings of the Korean Information Science Society Conference
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• 2001.10b
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• pp.487-489
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• 2001

본 논문은 구형 영상기반 가상환경에서 하나의 시점 영상 내에 포함되어 있는 임의의 물체를 모델링하여 3차원 운동이 가능한 시스템을 소개한다. 본 논문에서는 카메라 보정을 하지 않고, 물체에 대한 최소한의 기하학적 정보만을 이용하여 물체를 모델링하고, 모델링된 물체의 영상 기반 운동(image-based motion)의 가능성을 제시한다. 구현된 시스템은 구 환경에서의 하나의 시점 영상을 사영평면으로 간주하고 사용자에 의해 입력된 선과 점으로 투영된 3차원 물체의 2차원 모양을 모델링한다. 그리고 소실점을 이용해서 모델링된 입방체의 3차원 운동을 다룬다.

• Electrical & Electronic Materials
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• v.3 no.1
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• pp.9-19
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• 1990

본 연구에서는 산회물 혼합법, 솔-젤법, 공침법등의 세가지 방법으로 PbTiO$_{3}$분말을 제조하여 폴리머와 혼합 O-3 복합재료를 제작한 후, 하이드로폰으로의 응용을 위한 제 특성을 고찰하였다. 비유전상수는 PbTiO$_{3}$의 체적비 증가에 따라 지수함수적으로 증가하였으며 유전손실은 선형적으로 증가하였다. 수정입방체 모델로 부터 계산된 변형계수 n은 M-O, S-G, C-P의 경우 각각 0.724, 0.585, 0.483으로 나타났다. 압전 변형계수 d$_{33}$는 PbTiO$_{3}$의 체적비, 분극전장 및 분극 시간의 증가에 따라 증가하였으며 일정시간 경과후에는 포화값을 나타내었다.다.

• Journal of computational fluids engineering
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• v.13 no.3
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• pp.28-34
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• 2008

In engineering application of large eddy simulation, there are still questions as follows grid dependency on numerical results, the effect of upwind scheme against a calculation instability, appropriate boundary conditions dealing with turbulence fluctuation and the performance of SGS models. In this study, in order to develop the LES to the engineering application, large eddy simulation was carried out to investigate the effect of upwind scheme, turbulent subgrid model and the grid dependancy of the flow around a wall-mounted cube in a channel at Re=40,000 based on cubic height and bulk mean velocity. The computed velocities, turbulence quantities, separation and reattachment length were evaluated compared with the experimental results of R. Matinuzzi and C. Tropea.

• Proceedings of the Korean Information Science Society Conference
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• 2002.04a
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• pp.709-711
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• 2002

볼륨렌더링(volume rendering)은 3차원의 물체 내부를 가시화하기 위한 기법이다. 여기서는 물체를 복셀(voxel)이라 불리는 미소한 입방체나 미립자의 집합으로 표현하며 의료영상 등 다양한 분야에 이용된다. 볼륨렌더링은 전통적인 렌더링 방법으로 표현할 수 없는 물체의 내부나 반투명한 물체를 표현할 수 있는 장점이 있다. 하지만 방대한 데이터를 다루기 때문에 컴퓨터의 성능이 좋아야 하고 처리시간이 오래 걸린다. 미츠비시사는 PC에서 쉬어-웝(shear-warf) 방법을 기반으로 실시간 볼륨렌더링을 할 수 있는 전용 하드웨어인 볼륨프로(VolumePro)를 발표했다. 하지만 볼륨프로는 직교투영만을 하기 때문에 투시투영을 하지 못한다는 단점을 가지고 있다. 본 논문에서는 볼륨프로의 크로핑(Cropping)을 이용한 서브볼륨(Subvo1ume)을 활용하여 투시투영에 근접한 효과를 보여주는 방법을 제안한다.

• Magazine of the Korean Society of Agricultural Engineers
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• v.41 no.2
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• pp.70-79
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• 1999

The lower ground of structure, in which the strip loads, such as earth dams and embankments , are signiificantly working on , is required to be interpreted as a state of plane strain where the strain of intermediated principal stress direction is put '0' . The plane strain state is frquently observed in actural soil engineering case. For those case, drained stress-strain and strength behavior of Iksan weathered granite soil prepared in cubical specimens with cross-anisotropic fabric was studied by conventional triaxial compression, plane strain and cubial triaxial tests with independent control of the three principal stress. All specimens were loaded under conditions of principl stress directions fixed and aligned with the directions of the material axes. As a result of research , when a ground condition is analyzed under plane strain state, the shear strength obtained from the conventional triaxial compression test can be understimated.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 1998.11a
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• pp.45-49
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• 1998

3차원 스캐너 또는 스테레오 비전 등으로부터 입력된 거리 정보(Range Data)를 실제 응용프로 프로그램에 사용하기 위한 가상객체(Virtual Character)로 만들기 해서 는 우선 메쉬(mesh) 형태로 변환하는 작업 이 필수적이며, 기법들은 수십년 동안 활발히 연구되어 왔다. 많이 이용되는 방법은 초기 입력된 거리영상들의 각각의 점들이 연결관계 및 구조에 대한 정보를 입력 시점에서 알 수 있으므로, 각 면에 대해서는 쉽게 메쉬를 생성하여, 2차원 측정 단면 중심의 부조 형태로 메쉬를 활용하고 있지만. 3차원 가상객체가 요구되는 경우에는 측정단면별로 형성된 결과들을 하나의 메쉬로 생성하기 위해서는 짜깁기(Zippering)와 같은 어려운 작업이 추가로 필요하다. 본 논문에서는 개선된 3차원 행진입방체 방법과 간략화 기법을 적용하여 짜깁기(Zippering)을 사용하지 않고 가상객체를 생성하는 방법을 소개하려 한다.

• Magazine of the Korean Society of Agricultural Engineers
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• v.35 no.4
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• pp.106-118
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• 1993

The purpose of this study is to develop a multireservoir water balance model which may be used to evaluate rural water demands such as agricultural water, domestic water, industrial water and livestock water and to determine effective storage of reservoir. The model was verified to compare the observed reservoir release data with the simulated reservoir release data of the existing Munsan and Dongbu reservoirs located in the Gisan rural district for 3 years('87~'89). For model application, the effective storages of existing reservoirs(Munsan & Dongbu) were evaluated for 10-year frequency drought and that of newly planned reservoirs(Kumbok & Kudong) were determined for 10-year frequency drought. In addition, the behavior of effective storages for existing reservoirs were analyzed in the case of introducing new reservoirs in the existing system.