• 한국전산유체공학회:학술대회논문집
• /
• 한국전산유체공학회 2009년 추계학술대회논문집
• /
• pp.211-217
• /
• 2009

The numerical program has been developed for the purpose of the complicate geometries application using CIP method. The non-staggered, non-orthogonal, and unstructured grid system can be also used for the various geometries in the program. For validating CIP solver, the lid-driven cavity flow and solitary wave propagation flow are carried out. Test results show a good agreement with the verified results. The dynamic solver was used for the behavior of moving body. Interface process between the two solvers is introduced. The research was performed on the flow problem around torpedo and log and the flow problem in a tank in order to analyze the three phase flow problem Although the comparison to the verified results was not quantitatively performed, the trend of the results was reasonable.

• 로봇학회논문지
• /
• 제9권4호
• /
• pp.197-205
• /
• 2014

As computer vision algorithms are developed on a continuous basis, the visual information from vision sensors has been widely used in the context of simultaneous localization and mapping (SLAM), called visual SLAM, which utilizes relative motion information between images. This research addresses a visual SLAM framework for online localization and mapping in an unstructured seabed environment that can be applied to a low-cost unmanned underwater vehicle equipped with a single monocular camera as a major measurement sensor. Typically, an image motion model with a predefined dimensionality can be corrupted by errors due to the violation of the model assumptions, which may lead to performance degradation of the visual SLAM estimation. To deal with the erroneous image motion model, this study employs a local bundle optimization (LBO) scheme when a closed loop is detected. The results of comparison between visual SLAM estimation with LBO and the other case are presented to validate the effectiveness of the proposed methodology.

• Nuclear Engineering and Technology
• /
• 제46권2호
• /
• pp.263-272
• /
• 2014

Scattering source calculations using conventional spherical harmonic expansion may require lots of computation time to treat full-coupled three-dimensional photon-electron transport in a highly anisotropic scattering medium where their scattering cross sections should be expanded with very high order (e.g., $P_7$ or higher) Legendre expansions. In this paper, we introduce a modified scattering kernel approach to avoid the unnecessarily repeated calculations involved with the scattering source calculation, and used it with parallel computing to effectively reduce the computation time. Its computational efficiency was tested for three-dimensional full-coupled photon-electron transport problems using our computer program which solves the multi-group discrete ordinates transport equation by using the discontinuous finite element method with unstructured tetrahedral meshes for complicated geometrical problems. The numerical tests show that we can improve speed up to 17~42 times for the elapsed time per iteration using the modified scattering kernel, not only in the single CPU calculation but also in the parallel computing with several CPUs.

• 한국산업정보학회논문지
• /
• 제20권2호
• /
• pp.113-124
• /
• 2015

미리 선언된 구조를 이용하여 수집 저장된 정형적 데이터와는 달리 웹 2.0의 시대에서 일반 사용자들이 평상시에 사용하는 자연어 형태로 작성된 비정형 데이터 분석은 과거보다 훨씬 더 넓은 응용범위를 가지고 있다. 데이터 양이 폭발적으로 증가하고 있다는 특성뿐 만 아니라 인간의 감성이 그대로 표현된 특성을 가진 텍스트에서 의미 있는 정보를 추출하는 빅데이터 분석 기법을 텍스트마이닝(Text Mining)이라 하며 본 연구는 이를 주제로 하고 있다. 본 연구를 위해 오픈 소스인 통계분석용 소프트웨어 R 프로그램을 이용하였으며, 비정형 텍스트 문서를 웹 환경에서 수집, 저장, 전처리, 분석 작업과 시각화(Frequency Analysis, Cluster Analysis, Word Cloud, Social Network Analysis)작업 등의 과정에 관한 알고리즘 구현을 연구하였다. 특히, 연구자의 연구 영역 분석에 초점을 더욱 높이기 위해 Data Dictionary를 참조한 키워드 추출 기법을 사용하였다. 실제 사례에 적용한 R은 다양한 OS 구동, 일반적 언어와의 인터페이스 지원 등 통계 분석용 소프트웨어로써 매우 유용하다는 점을 발견할 수 있었다.

• 대한기계학회논문집B
• /
• 제32권1호
• /
• pp.70-77
• /
• 2008

A pre-processing program based on the OOP(object-oriented programming) concept has been developed. The program consists of the input of a 2D or 3D flow problem to a CFD program by means of an user-friendly interface and the subsequent transformation of this input into a form suitable for the solver(PowerCFD) using unstructured cell-centered method. User-friendly GUI(graphic user interface) has been built on the base of MFC(Microsoft Foundation Class). The program is organized as modules by classes based on VTK(Visualization ToolKit)-library, and these classes are made to function through inheritance and cooperation which is an important and valuable concept of object-oriented programming. The major functions of this program are introduced and demonstrated, which include mesh generation, boundary settings, solver settings, generation of grid connectivity and geometric data etc.

• 한국전산유체공학회:학술대회논문집
• /
• 한국전산유체공학회 2009년 추계학술대회논문집
• /
• pp.65-70
• /
• 2009

In this paper a hybrid grid generation program for general 2-D region is introduced. The program is developed by using JAVA programming language, and it can be used either as an application program on a local computer or as an applet in the network environment. The hybrid grid system for a 2-D problem means a combination of triangular cells and quadrilateral cells, and it can offer both of the high flexibility of triangular cells and the high accuracy and efficiency of structured-type quadrilateral cells. To accommodate a quadrilateral-cell region and a triangular-cell region into one computational domain, it is importance to take good care of the interface between two different regions so that overall good grid quality can be maintained. In this research advancing layer method(ALM) augmented by elliptic smoothing method is used for the quadrilateral-cell region and advancing front method(AFM) is used for the triangular-cell region. A special treatment technique for the interface between those two regions is also developed. The interface treatment technique is basically to prevent the propagation of small cell size due to ALM method into the triangular region and maintain the smooth transition of cell-size scale between two different regions. By applying current technique high-quality hybrid grids for general 2-D regions can be easily generated, and typical grid generation results and flow solutions are demonstrated.

• 한국환경교육학회지:환경교육
• /
• 제16권1호
• /
• pp.34-47
• /
• 2003

The purpose of this study is to analyze the program development process of a nonformal environmental education(EE) program in detail. For the purpose, following research questions were answered in "the Nature School in the Forest" program in Eco-Club 1) What is the program development process? 2) What is the role of staffs, program developers, in the program development process? What are the meanings of their pedagogical approach? 3) With the findings of this study, how is the researcher able to develop ground theory for community-based nonformal EE, and to promote theoretical discussion for field improvement? The data were mainly gathered through participation observation and unstructured interview. And the data were analyzed by qualitative techniques such as clustering, factoring, noting pattern and themes, seeing plausibility, making metaphors, and building logical chain of evidence. The following conclusion comes out of the findings of this study. "The Nature School in the Forest" program is a educational device which the community-based NGO chose as a strategy to change individuals and community with its ideological purpose. And the program development process was the contiuous group decision-making process among staffs and volunteers. Consequently "the Nature School in the Forest" program is a circulated process of the voluntary activists training and their participation in program operation.

• 대한기계학회논문집B
• /
• 제32권1호
• /
• pp.62-69
• /
• 2008

A post-processing program based on the OOP(Object-Oriented Programming) concept has been developed for flow visualization of the flow analysis code(PowerCFD) using unstructured cell-centered method. User-friendly GUI(GTaphic User Interface) has been built on the base of MFC(Microsoft Foundation Class). The program is organized as modules by classes including those based on VTK(Visualization ToolKit)-library, and these classes are made to function through inheritance and cooperation which is an important and valuable OOP concept. The major functions of this post-processor program are introduced and demonstrated, which include mesh plot, contour plot, vector plot, surface plots, cut plot, clip plot, xy-plot and streamline plot as well as view manipulation (translation, rotation, scaling etc).

• 로봇학회논문지
• /
• 제18권3호
• /
• pp.251-259
• /
• 2023

In the path traveling of differential-drive robots, the steering controller plays an important role in determining the path-following performance. When a robot with a pure-pursuit algorithm is used to continuously drive a right-angled driving path in an unstructured environment without turning in place, the robot cannot accurately follow the right-angled path and stops driving due to the ground and motor load caused by turning. In the case of pure-pursuit, only the current robot position and the steering angle to the current target path point are generated, and the steering component does not reflect the speed plan, which requires improvement for precise path following. In this study, we propose a driving algorithm for differentially driven robots that enables precise path following by planning the driving speed using the radius of curvature and fusing the planned speed with the steering angle of the existing pure-pursuit controller, similar to the Model Predict Control control that reflects speed planning. When speed planning is applied, the robot slows down before entering a right-angle path and returns to the input speed when leaving the right-angle path. The pure-pursuit controller then fuses the steering angle calculated at each path point with the accelerated and decelerated velocity to achieve more precise following of the orthogonal path.

• 한국컴퓨터정보학회논문지
• /
• 제17권7호
• /
• pp.23-32
• /
• 2012

프로그램 검증을위해 사용되는방법으로 프로그램을 검증조건으로 변환하여정리증명기를 통해 프로그램의유효성을 확인하는 방법이 있다. 검증조건 생성을 통한 프로그램의 검증의 경우 검증조건은 프로그램을 검증하기 위한 충분하고 정확한 정보를 가지고 있어야한다. 하지만 프로그램의 변환을 통해 생성된 검증조건의 경우 논리식만으로 구성되어 있어 사용자가 쉽게 그 내용을파악할 수 없다. 본 논문에서는 가독성이 떨어지는 검증조건을 시각화하는 프로그램을 구현하였다. 프로그램을 통해 검증조건을 구성하고 있는 논리식간의 관계 등을 비롯한 정보를 보다 쉽게 확인할 수 있다.