• 한국해양공학회지
• /
• 제33권2호
• /
• pp.116-122
• /
• 2019

Among the various wave power systems, Salter's duck (rotor) is one of the most effective wave absorbers for extracting wave energy. The rotor shape is designed such that the front part faces the direction of the incident wave, which forces it to bob up and down due to wave-induced water particle motion, whereas the rear part, which is mostly circular in shape, reflects no waves. The asymmetric geometric shape of the duck makes it absorb energy efficiently. In the present study, the rotor was investigated using WAMIT (a program based on the linear potential flow theory in three-dimensional diffraction/radiation analyses) in the frequency domain and verified using OrcaFlex (design and analysis program of marine system) in the time domain. Then, an experimental investigation was conducted to assess the performance of the rotor motion based on the model scale in a two-dimensional (2D) wave tank. Initially, a free decay test (FDT) was carried out to obtain the viscous damping coefficient. The pitch response was extracted from the experimental time series in a periodic regular wave for two different wave heights (1 cm and 3 cm). In addition, the viscous damping coefficient was calculated from the FDT result and fluid forces, obtained from WAMIT, are incorporated into the final response of the rotor. Finally, a comparative study based on experimental and numerical results (WAMIT & OrcaFlex) was performed to confirm the performance reliability of the designed rotor.

• Journal of Magnetics
• /
• 제16권3호
• /
• pp.288-293
• /
• 2011

Generally, the discontinuous armature permanent magnet linear synchronous motor (PM-LSM) is composed by the stator block (accelerator, re-accelerator, and decelerator) and the free running section. However, the stationary discontinuous armature design involves the velocity variation of the mover during drive when the armature's non-installation part changes over to installation part as a result of the outlet edge of the armature. Therefore, we considered deforming the shape of the outlet edge at the armature and apply skew on the permanent magnet by displacing the two magnet segments of each pole. This paper presents the results of a three-dimensional (3-D) numerical analysis with a finite element method (FEM) of the force exerted by the outlet edge.

• 소성∙가공
• /
• 제23권3호
• /
• pp.145-150
• /
• 2014

Precision control of the slab is crucial for product quality and production economy in hot strip mills. The current study presents a new model for predicting width spread of a slab with a rectangular cross section during roughing. The model is developed on the basis of the extremum principle for a rigid plastic material and a three dimensional admissible velocity field. This model incorporates the effect of process variables such as the shape factor and the ratio of width to thickness. We compare the results of this model to 3-D finite element (FE) process simulations and also to results from a previous study.

• 천문학회지
• /
• 제46권3호
• /
• pp.125-131
• /
• 2013

We present the relation between the genus in cosmology and the Betti numbers for excursion sets of three- and two-dimensional smooth Gaussian random fields, and numerically investigate the Betti numbers as a function of threshold level. Betti numbers are topological invariants of figures that can be used to distinguish topological spaces. In the case of the excursion sets of a three-dimensional field there are three possibly non-zero Betti numbers; ${\beta}_0$ is the number of connected regions, ${\beta}_1$ is the number of circular holes (i.e., complement of solid tori), and ${\beta}_2$ is the number of three-dimensional voids (i.e., complement of three-dimensional excursion regions). Their sum with alternating signs is the genus of the surface of excursion regions. It is found that each Betti number has a dominant contribution to the genus in a specific threshold range. ${\beta}_0$ dominates the high-threshold part of the genus curve measuring the abundance of high density regions (clusters). ${\beta}_1$ dominates the genus near the median thresholds which measures the topology of negatively curved iso-density surfaces, and ${\beta}_2$ corresponds to the low-threshold part measuring the void abundance. We average the Betti number curves (the Betti numbers as a function of the threshold level) over many realizations of Gaussian fields and find that both the amplitude and shape of the Betti number curves depend on the slope of the power spectrum n in such a way that their shape becomes broader and their amplitude drops less steeply than the genus as n decreases. This behaviour contrasts with the fact that the shape of the genus curve is fixed for all Gaussian fields regardless of the power spectrum. Even though the Gaussian Betti number curves should be calculated for each given power spectrum, we propose to use the Betti numbers for better specification of the topology of large scale structures in the universe.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 1996년도 한국자동제어학술회의논문집(국내학술편); 포항공과대학교, 포항; 24-26 Oct. 1996
• /
• pp.928-931
• /
• 1996

It is necessary to develop the simulator for the test of stability and torque before the walking experiment of biped robot, because a robot may be damaged in an actual experiment. This thesis deals with the development of three-dimensional simulator for improving efficiency and safety during development and experimentation. The simulator is composed of three parts-solving dynamics, rendering pictures and communicating with the robot. In the first part, the D-H parameter and parameter of links can be loaded from the file and edited in the program. The results are obtained by using the Newton-Euler method and are stored in the file. Through the above process, the proper length of link and driving force can be found by using simulator before designing the robot. The second part is organized so that the user can easily see a specific value or a portion he wants by setting viewing parameters interactively. A robot is also shown as a shaded rendering picture in this part. In the last part, the simulator sends each desired angle of joints to the robot controller and each real angle of joints is taken from the controller and passed to the second part. The safety of the experiment is improved by driving the robot after checking whether the robot can be actuatable or not and whether the ZMP is located within the sole of the foot or not for a specific gait. The state of the robot can be easily grasped by showing the shaded rendering picture which displays the position of the ZMP, the driving force and the shape of robot.

• 디지털콘텐츠학회 논문지
• /
• 제9권1호
• /
• pp.149-155
• /
• 2008

본 논문은 3D 그래픽 기술을 이용하여 성형 시술 전후의 입체 얼굴을 제작하여 얼굴 성형 시술자의 만족도를 높이는 응용프로그램 시스템에 관한 구현 및 연구이다. 사용자의 실물에 최대한 유사한 원형 3D 입체 얼굴을 Pre-Processing 과정 및 Face-Part-Making 과정으로 구분하여 각 과정에 필요한 기술들을 사용하여 구현하였다. 또한 각 얼굴 부위를 담당하는 변형 Controller를 구현하여 제작된 입체 얼굴의 변화를 볼 수 있는 성형 제작 시스템을 구현하였다. 본 논문에서 구현한 얼굴 성형 제작 시스템은 현재 성형외과 등에서 활용되고 있는 2D 시스템에 비하여 효율성과 정확성, 만족도 등에서 보다 좋은 결과를 보여주고 있다.

• 지구물리와물리탐사
• /
• 제17권1호
• /
• pp.21-27
• /
• 2014

심해탐사를 위해 새롭게 개발된 소형 루프형 해양 전자탐사 시스템의 실해역 실험 결과의 반응 양상을 적분방정식 기반의 3차원 모델링을 통하여 분석하였다. 수심 약 300 m 해저환경에서 획득한 금속 이상체의 전자기 반응 양상에 대한 영향인자를 분석하기 위해 이상체의 크기와 모양을 다르게 설정하여 모델링을 수행하였다. 모델링 결과 분석을 통하여 이상체의 모양이 크기보다 반응 양상에 더 큰 영향을 주는 것을 확인하였다. 탐사고도와 주파수에 따른 반응값 변화를 알아보기 위해 모델링을 수행하였고 이를 통해 일정한 탐사 고도 유지의 필요성과 주파수 대역에 따른 허수부의 민감도를 확인하였다. 또한 탐사 고도와 주파수에 따른 반응값을 단면 그래프로 나타내어 시스템에 사용되는 주파수 대역에 대한 적절한 탐사고도를 제시하였다. 본 연구를 통해 도출된 결과는 해저 열수광상 실해역 탐사 설계 시 매개변수 설정에 있어 유용한 정보를 줄 것으로 예상된다.

• 한국실내디자인학회논문집
• /
• 제19권6호
• /
• pp.47-58
• /
• 2010

Frank Lloyd Wright(1867-1959) was regarded as the pioneer of the modern architecture in the beginning and transition period of 20th century. His works have the pure shape form which have the deep relationship with the organic architecture. Wright told himself that the Froebel System had an influence on his works a lot. This study have researched about the three dimensional application of the Froebel System in his works with assembling and disassembling. Also the two dimensional application in the diagonal and circular plans are the one of the subjects here. The following conclusions are reached. First, The similar of the Wright's works and the Froebel System was the application of the similar principles rather than the copy of the method, which are the accent of the center, the composition of the part and whole, the understanding of the composition principle through the unit system and the unfolding of the crystal by rotation. Even thought the Wright's works have the triangle, square, hexagonal shape, the way of the expansion from the centered space was same. Also the space formed by the division of the center space, unfolds making the part and whole by overlap and continuation. The 2nd Froebel make space decided by the Net and Crystal Lattices which have the crystal characteristics by the rotation. The new geometric architecture, pinwheel, was created by this method. The application of the Froebel in the Wright's works have the several sets which are the 3th, 4th, 5th, 6th Froebels, 2nd, 7th Froebels and the 3th, 5th, 9th Froebels. The geometrical analysis of the square shape and the diagonal shape of the Wright's works was possible. The unfolding of the centered space can be found in the Guggenheim Museum using the analysis of the circular geometric of the 9th Froebel. The above study proves that the Froebel was not a mere tool for the basic shape training but also the main body of Wright's works which consists of the organic idea and philosophy of the space.

• 한국측량학회지
• /
• 제25권2호
• /
• pp.99-105
• /
• 2007

본 연구는 항공사진을 이용 3차원 도로설계 시뮬레이션을 적용하는데 그 목적이 있다. 기존의 수치지도를 이용한 도로설계 방법대신 수치지도에서 정확히 나타나지 않는 지형과 지물을 수치항공사진을 이용하여 3차원 도로설계에 적용하였다. 먼저 항공사진을 이용해서 정사사진을 만들고 DEM을 추출하여 수치표고모델을 생성하였다. 그리고 실제 평면 설계에 쓰이는 좌표값을 3차원설계에 적용함으로서, 도로 노선 및 경관분석에 많은 도움이 될 것으로 보인다. 또한 Virtual GIS를 이용하므로 도시계획, 식물, 토양, 수로 또는 도로형태, 홍수계획 등 많은 인자들이 평가에 사용되며 이러한 노선설계기준에 따라서 3차원 시뮬레이션을 적용하여 그 효과를 검토하고자 한다. 본 논문에서는 구조물 3차원 설계에 관한 기초적인 연구를 시행하였으며, 3차원설계를 통해 의사결정시 효율적인 판단을 할 수 있었다. 향후, 환경 친화적 시공 및 설계에 대한 연구가 이루어져야 될 것으로 판단된다.

• 보존과학회지
• /
• 제27권2호
• /
• pp.181-190
• /
• 2011

2006년 전남 고흥군 안동고분에서 발굴된 5세기의 백제 금동관모의 3D 스캐닝작업을 통하여 정밀실측 및 디지털 영상복원을 실시하였다. 3D 스캐닝은 대상물의 정밀한 형상을 3차원 공간상에 구현하여 디지털데이터로 보존하는데 목적이 있다. 데이터 구축은 3차원 형상과 색상정보를 획득하는 과정인 3D 스캐닝(부위별 원시 데이터 촬영) - 3D 모델링(원시 데이터 정합 및 비촬영부 재생과 손실부 복원) - CG영상 제작 순으로 이루어 졌다. 복원 CG영상은 원시데이터의 정합된 형상을 기초근거로 하였고 도면상(CAD)의 각 부재 실측 수치를 참고하여 제작하였다. 이때 비촬영 부분과 소실된 부분은 각 부재의 실측자료와 더불어 옛 백제지역에서 출토된 5~8세기의 관모들을 조사하여 복원하였다. 이러한 3D영상 복원은 손상된 유물의 복원방법 중 하나로써 고증과 검증을 통해 유물의 직접적인 손상 없이 유물을 재구성하여 복원함으로써 역사적 및 학술적 가치향상과 유물 복원에 의미가 있다고 하겠다.