• Proceedings of the IEEK Conference
• /
• 2002.07b
• /
• pp.1324-1326
• /
• 2002

This paper concerns the development of distributed interactive simulation of a road traffic system. The simulation involved models of multiple and distributed road vehicles running on different locations. The simulation system represented a traffic system as if the distributed simulation models were in the same environment. The development of the distributed road traffic simulation was based on High Level Architecture (HLA), a state-of-the-art IEEE standard for the distributed and real-time simulation. Other work concerned modeling and simulating the road vehicles and building the map database for the virtual distributed shared environment. The information used in the simulation system was only in X-axis and Y-axis as the insignificant data in the Z-axis was omitted to simplify the simulation. However, the traffic system has visualized a 3-D coordinate system. The road vehicle models were able to avoid collision. The next direction of a vehicle can be chosen from the provided choices of further paths.

• Proceedings of the Korean Operations and Management Science Society Conference
• /
• 1992.04b
• /
• pp.545-554
• /
• 1992

본 논문에서는 복합형상의 금형을 가공하기 위하여 필요한 공구와 가공경로를 자동으로 생성해 주는 자동공정계획(CAPP)방법을 제시한다. 금형곡면은 일반적으로 복잡한 형상의 자유곡면들의 조합으로 이루어 지는데 육면체 형상의 소재로부터 원하는 금형곡면을 가공하는데는 수십시간의 기계가공 시간이 소요되며 또한 NC Code를 준비하는데도 같은정도의 시간이 소요된다. 금형곡면의 NC가공에 있어서 또다른 어려움은 공구의 과부하와 공구간섭이 빈번하게 발생할 수 있다는 점이다. 제안하는 자동공정계획방법은 전처리, 공정계획, 공구경로 생성의 3단계로 구성된다. 자동공정계획시스템의 입력정보는 1) 생성될 곡면형상 2) 가공할 소재형상 3) 가공공구 셀(드릴, 볼 엔드밀, 플렛 엔드밀), 절삭성 데이타등이다. 전처리 단계에서는 곡면모델러로부터 생성된 입력 형상을 Z-map이라 부르는 자료구조로 변환한다. 두번째 단계에서는 절삭 가공작업의 순서가 사용되는 공구와 함께 후방순환법에 의하여 결정된다. 그리고 실제 가공될 NC공구경로가 마지막 세번째 단계에서 생성된다.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 1997.04a
• /
• pp.782-787
• /
• 1997

This paper proposes methods for pencil machining and uncut area machining. Based on Z-map represented by triangular facets, self-intersection-free offset surface is generated with K-offset method in case of ball mill and flat mill Pencil machining can elliminate overload area before main machining rough, semi-finish and finish cutting,preventing fluctuations of cutting forces in concave regions form causing bad machining condition. Low productivity is caused by uncut area which has excessive or irreguar finishing allowance. Uncut area machining has the finishing allowance keep uniformly on part surface. This paper deals with two types of uncaut area, machining detection of excessive area and user-defined area.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 1997.10a
• /
• pp.37-42
• /
• 1997

Off-line feed rate scheduling is an advanced methodology to automatically determine optimum feed rates for the optimization of NC code. However, the present feed rate scheduling systems have lim~tations to generate the optimized NC codes because they use the material removal rate or non-generalized cutting force model. In this paper, a feed rate scheduling system based on an improved cutting force model that can predrct cutting forces exactly in general machining was presented. Original blocks of NC code were divided to small ones with the modified feed rates to adjust the peak value of cutting forces to a constant vale. The characteristic of acceleration and deceleration for a given machrne tool was considered when off-line feed rate scheduhng was performed. Software for the NC code optimization was developed and applied to pocket machining simulation.

• Wind and Structures
• /
• v.20 no.4
• /
• pp.565-578
• /
• 2015

A wind energy assessment is an integrated analysis of the potential of wind energy resources of a particular area. In this work, the wind energy potentials for Mauritius have been assessed using a Computational Fluid Dynamics (CFD) model. The approach employed in this work aims to enhance the assessment of wind energy potentials for the siting of large-scale wind farms in the island. Validation of the model is done by comparing simulated wind speed data to experimental ones measured at specific locations over the island. The local wind velocity resulting from the CFD simulations are used to compute the weighted-sum power density including annual directional inflow variations determined by wind roses. The model is used to generate contour maps of velocity and power, for Mauritius at a resolution of 500 m.

• IEMEK Journal of Embedded Systems and Applications
• /
• v.10 no.2
• /
• pp.73-79
• /
• 2015

Dynamic culling scheme is usually implemented to handle overhead caused by rendering the massive large-scale terrain data in flight simulator. However, existing culling scheme without considering altitude is not suitable for flight simulator due to additional computational overhead. To solve this problem, in this paper, we propose hybrid approach by applying two dynamic culling schemes depending on altitude. In addition, we remove unnessary computational overhead by creating different z-map resolution when aircraft changes its altitude. The proposed scheme is implemented with open graphic library and tested with real terrain data. Through the experimental results, we can recognize the improved rendering speed about 8 to 73 percents as compared to existing scheme.

• Journal of applied mathematics & informatics
• /
• v.38 no.3_4
• /
• pp.311-334
• /
• 2020

The solution of the elliptic partial differential equation has interface singularity at the points which are either the intersections of interfaces or the intersections of interfaces with the boundary of the domain. The singularities that arises in the elliptic interface problems are very complex. In this article we propose an exponentially accurate nonconforming spectral element method for these problems based on [7, 18]. A geometric mesh is used in the neighbourhood of the singularities and the auxiliary map of the form z = ln ξ is introduced to remove the singularities. The method is essentially a least-squares method and the solution can be obtained by solving the normal equations using the preconditioned conjugate gradient method (PCGM) without computing the mass and stiffness matrices. Numerical examples are presented to show the exponential accuracy of the method.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.19 no.2
• /
• pp.251-259
• /
• 2010

It is presented in this study a new efficient intelligent machining strategy, which can be used to remove the uncut volume at the boundary region of curved surfaces caused by cutter interference. The geometric form definitions and recognition of topological features of the surface triangulation mesh are used to generate cutter paths along successive and interconnected steepest pathways, that minimize the cusp height left after flat end milling. In order to machine the uncut volume gradually, the z-map cutter centers are adjusted to avoid cutter interference for the 6 kinds of avoidance types. And then, the generative subsequent paths are sequenced to determine the second step cutter paths for the next uncut volume. For the 2 kinds of test models with convex and concave surface region, the implemented software algorithm is evaluated by investigating the residual swelling of uncut volume for each machining step.

• Journal of the Korean Mathematical Society
• /
• v.46 no.2
• /
• pp.249-256
• /
• 2009

Let $G{\otimes}G$ be the tensor square of a group G. The set of all elements a in G such that $a{\otimes}g\;=\;1_{\otimes}$, for all g in G, is called the tensor centre of G and denoted by $Z^{\otimes}^$(G). In this paper some properties of the tensor centre of G are obtained and the capability of the pair of groups (G, G') is determined. Finally, the structure of $J_2$(G) will be described, where $J_2$(G) is the kernel of the map $\kappa$ : $G{\otimes}\;{\rightarrow}\;G'$.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 1995.04b
• /
• pp.396-399
• /
• 1995

In this study, Acquisition system is proposed to acquire 3 dimensional data of the free surface model using direct pulse control to machining center. Todo this, I/F to connect between manual operating handle and computer is made, and 3 dimensional shape measuring algorithm using Z-map is applied. The 3 dimensional shape data of the free surface model measured by laser displacement sensor and electric touch probe are achieved directly. Performance of the proposed system is evaluated through measurement of various shape model.