• Nuclear Engineering and Technology
• /
• 제55권6호
• /
• pp.2230-2245
• /
• 2023

KANT (KAIST Advanced Nuclear Tachygraphy) is a PWR core simulator recently developed at Korea Advance Institute of Science and Technology, which solves three-dimensional steady-state and transient multigroup neutron diffusion equations under Cartesian geometries alongside the incorporation of thermal-hydraulics feedback effect for multi-physics calculation. It utilizes the standard Nodal Expansion Method (NEM) accelerated with various Coarse Mesh Finite Difference (CMFD) methods for neutronics calculation. For thermal-hydraulics (TH) calculation, a single-phase flow model and a one-dimensional cylindrical fuel rod heat conduction model are employed. The time-dependent neutronics and TH calculations are numerically solved through an implicit Euler scheme, where a detailed coupling strategy is presented in this paper alongside a description of nodal equivalence, macroscopic depletion, and pin power reconstruction. For validation of the steady, transient, and depletion calculation with pin power reconstruction capacity of KANT, solutions for various benchmark problems are presented. The IAEA 3-D PWR and 4-group KOEBERG problems were considered for the steady-state reactor benchmark problem. For transient calculations, LMW (Lagenbuch, Maurer and Werner) LWR and NEACRP 3-D PWR benchmarks were solved, where the latter problem includes thermal-hydraulics feedback. For macroscopic depletion with pin power reconstruction, a small PWR problem modified with KAIST benchmark model was solved. For validation of the multi-physics analysis capability of KANT concerning large-sized PWRs, the BEAVRS Cycle1 benchmark has been considered. It was found that KANT solutions are accurate and consistent compared to other published works.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제14권9호
• /
• pp.3782-3796
• /
• 2020

A three-dimensional (3D) reconstruction is an important research area in computer vision. The ability to detect and match features across multiple views of a scene is a critical initial step. The tracking matrix W obtained from a 3D reconstruction can be applied to structure from motion (SFM) algorithms for 3D modeling. We often fail to generate an acceptable number of features when processing face or medical images because such images typically contain large homogeneous regions with minimal variation in intensity. In this study, we seek to locate sufficient matching points not only in general images but also in face and medical images, where it is difficult to determine the feature points. The algorithm is implemented on an adaptive threshold value, a scale invariant feature transform (SIFT), affine SIFT, speeded up robust features (SURF), and affine SURF. By applying the algorithm to face and general images and studying the geometric errors, we can achieve quasi-dense matching points that satisfy well-functioning geometric constraints. We also demonstrate a 3D reconstruction with a respectable performance by applying a column space fitting algorithm, which is an SFM algorithm.

• 한국정밀공학회지
• /
• 제24권5호
• /
• pp.62-67
• /
• 2007

A simple dimension measuring method for the measurement of human bust has been developed using projection moire. The 3-D data of a human bust was calculated from the 2dimensional image information obtained by the stripe using projection moire. The creation of 3-D geometric shape by digitizing real objects has been widely investigated in reverse engineering(RE). This procedure generally consists of three basic steps: data capture, data alignment and model reconstruction. In order to achieve a complete model, multiple scans must be taken and aligned.

• Nuclear Engineering and Technology
• /
• 제49권6호
• /
• pp.1339-1345
• /
• 2017

In the framework of the EU funded project NURESAFE, the subchannel code CTF and the neutronics code DYN3D were integrated and coupled on the NURESIM platform. The developments achieved during this 3-year project include assembly-level and pin-by-pin multiphysics thermal hydraulics/neutron kinetics coupling. In order to test this coupling, a PWR rod ejection transient was simulated on a MOX/UOX minicore. The transient is simulated using two different models of the minicore. In the first simulation, both codes model the core with an assembly-wise resolution. In the second simulation, a pin-by-pin fuel-centered model is used in CTF for the central assembly, and a pin power reconstruction method is applied in DYN3D. The analysis shows the influence of the different models on global parameters, such as the power and the average fuel temperature, but also on local parameters such as the maximum fuel temperature.

• 한국수학교육학회지시리즈D:수학교육연구
• /
• 제8권3호
• /
• pp.175-182
• /
• 2004

The design of learning environments which encourage students to work in a creative manner on mathematical problems is a creative process in itself. The concept of the Saturday University program is described in which pre-service teachers are guided at teaching students in extra-curriculum activities on interdisciplinary topics. In the process of the didactical reconstruction of mathematical problems, the pre-service teachers go through the stages of a revolving door model y.

• Maxillofacial Plastic and Reconstructive Surgery
• /
• 제40권
• /
• pp.4.1-4.4
• /
• 2018

Background: Along with the advances in technology of three-dimensional (3D) printer, it became a possible to make more precise patient-specific 3D model in the various fields including oral and maxillofacial surgery. When creating 3D models of the mandible and maxilla, it is easier to make a single unit with a fused temporomandibular joint, though this results in poor operability of the model. However, while models created with a separate mandible and maxilla have operability, it can be difficult to fully restore the position of the condylar after simulation. The purpose of this study is to introduce and asses the novel condylar repositioning method in 3D model preoperational simulation. Methods: Our novel condylar repositioning method is simple to apply two irregularities in 3D models. Three oral surgeons measured and evaluated one linear distance and two angles in 3D models. Results: This study included two patients who underwent sagittal split ramus osteotomy (SSRO) and two benign tumor patients who underwent segmental mandibulectomy and immediate reconstruction. For each SSRO case, the mandibular condyles were designed to be convex and the glenoid cavities were designed to be concave. For the benign tumor cases, the margins on the resection side, including the joint portions, were designed to be convex, and the resection margin was designed to be concave. The distance from the mandibular ramus to the tip of the maxillary canine, the angle created by joining the inferior edge of the orbit to the tip of the maxillary canine and the ramus, the angle created by the lines from the base of the mentum to the endpoint of the condyle, and the angle between the most lateral point of the condyle and the most medial point of the condyle were measured before and after simulations. Near-complete matches were observed for all items measured before and after model simulations of surgery in all jaw deformity and reconstruction cases. Conclusions: We demonstrated that 3D models manufactured using our method can be applied to simulations and fully restore the position of the condyle without the need for special devices.

• 한국통신학회논문지
• /
• 제29권3C호
• /
• pp.419-425
• /
• 2004

본 논문은 카메라로 찍은 투사 사영(Perspective Projection)의 한 영상으로부터 물체의 크기와 위치를 계산하기 위해서 3 개의 소실 점만을 사용해서 계산하는 새로운 방법을 제안한다. 우리의 접근 방법은 투사 사영의 영상으로부터 초점 거리(Focal Length), 회전 행렬(Rotation Matrix) 등의 정보들 없이 3개의 소실 점만을 가지고 계산하는 방법이다. 물체는 꼭지점(vertices)의 좌표가 크기 벡터 v 의 선형 함수로서 표현할 수 있는 다각형으로써 모델이 된다는 것을 가정한다. 이 재구성의 입력은 영상에서 특징 점과 모델에서 특징 점 사이 대응점의 집합으로 표현할 수 있다. 이 매개 변수 모델의 각각 크기를 최적화하기 위해서, 재구성의 최적화는 동일하게 매개 변수 공간을 샘플링에 의한 최적화기에 대하여 다중 시작점(multiple starting points)을 발생하는 다중 시작(multi-start) 방법을 가지는 표준 비선형 최적화 기법을 효과적으로 해결할 수가 있다.

• IEIE Transactions on Smart Processing and Computing
• /
• 제5권4호
• /
• pp.294-301
• /
• 2016

In this paper, we present methods to efficiently parallelize iterative 3D image reconstruction by exploiting trigeneous devices (three different types of device) at the same time: a CPU, an integrated GPU, and a discrete GPU. We first present a technique that exploits single instruction multiple data (SIMD) architectures in GPUs. Then, we propose a performance estimation model, based on which we can easily find the optimal data partitioning on trigeneous devices. We found that the performance significantly varies by up to 6.23 times, depending on how SIMD units in GPUs are accessed. Then, by using trigeneous devices and the proposed estimation models, we achieve optimal partitioning and throughput, which corresponds to a 9.4% further improvement, compared to discrete GPU-only execution.

• Journal of Electrical Engineering and Technology
• /
• 제13권2호
• /
• pp.781-789
• /
• 2018

This paper proposes a new approach utilizing empirical mode decomposition (EMD) reconstruction to process vibration signals of a transformer under DC bias caused by high voltage direction transmission (HVDC), which is the potential cause of additional vibration and noise from transformer. Firstly, the Calculation Method is presented and a 3D model of transformer is simulated to analyze transformer deformation characteristic and the result indicate the main vibration is produced along axial direction of three core limbs. Vibration test system has been built and test points on the core and shell of transformer have been measured. Then, the signal reconstruction method for transformer vibration based on EMD is proposed. Through the EMD decomposition, the corrupted noise can be selectively reconstructed by the certain frequency IMFs and better vibration signals of transformer have been obtained. After EMD reconstruction, the vibrations are compared between transformer in normal work and with DC bias. When DC bias occurs, odd harmonics, vibration of core and shell, behave as a nonlinear increase and the even harmonics keep unchanged with DC current. Experiment results are provided to collaborate our theoretical analysis and to illustrate the effectiveness of the proposed EMD method.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 2001년도 ICCAS
• /
• pp.153.5-153
• /
• 2001

This paper presents a simple modeling system that constructs 3D models from an indoor cylindrical environment map using all of the available geometry of the interior structure such as vertical and horizontal lines and parallel and perpendicular planes. The indoor scene abstract model is created through this system and the navigation through the process of 3D reconstruction. This system first automatically detects the vanishing points in a cylindrical environment map from parallel lines and planes, and determines the indoor scene topology previously defined using this information. The determined topology enables he user intervention UI simply construct a 3D model by using the photogrammetry. The modeling system can be ...