• Title/Summary/Keyword: Hole Finding

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EFFICIENT HOLE FINDING METHOD FOR OVERSET GRID SYSTEM (중첩 격자계의 효율적 Hole Finding 기법)

  • Kim B.S.;Ko S.H.
    • Journal of computational fluids engineering
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    • v.11 no.2 s.33
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    • pp.62-66
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    • 2006
  • In this paper an automated hole-finding method for overset grids is introduced which uses recursive octree-cell division. A graphic program which enables the user to do the hole-cutting with ease is also introduced. Using this program it is found that there is an optimum combination of the level of octree division and vector calculation for the efficient and fast hole finding.

Efficient Hole Finding Method for Overset Grid System (중첩 격자계의 효율적 Hole Finding 기법)

  • Kim B. S.;Ko S. H.
    • 한국전산유체공학회:학술대회논문집
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    • 2004.10a
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    • pp.83-86
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    • 2004
  • In this paper an automated hole-finding method for overset grids is introduced which uses recursive octree-cell division. A graphic program which enables the user to do the hole-cutting with ease is also introduced. Using this program it was found that a proper combination of the level of octree division and vector calculation should be used for efficient and fast hole finding.

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Passage Feature Recognition Algorithm for Automatic Parting Surface Generation in Plastic Injection Mold (플라스틱 사출 금형의 분할면 자동 생성을 위한 관통 특징 형상 추출 알고리즘의 개발)

  • 정강훈;이건우
    • Korean Journal of Computational Design and Engineering
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    • v.5 no.2
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    • pp.196-205
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    • 2000
  • This paper proposes a topology-based algorithm for recognizing the passage features using a concept of multi-face hole loop. The Multi-face hole loop is a concetpual hole loop that is formed over several connected faces. A passage feature is recognized in the proposed approach by two multi-face hole loops that constitute its enterance and exit. The algorithm proposed in this paper checks the connectivity of the two multi-face hole loops to recognize passage features. The total number of passage features in a part is calculated from Euler equation and is compared with the number of found passage features to decide when to terminate. To find all multi-face hole loops in a part, this paper proposes an algorithm for finding all combinations of connected faces. The edge convexity is used to judge the validity of multi-face hole loops. By using the algorithm proposed in this paper, the passage features could be recognized effectively. The approach proposed in this paper is illustrated with several example parts.

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A Sensing Radius Intersection Based Coverage Hole Recovery Method in Wireless Sensor Network (센서 네트워크에서 센싱 반경 교차점 기반 홀 복구 기법)

  • Wu, Mary
    • Journal of Korea Multimedia Society
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    • v.24 no.3
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    • pp.431-439
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    • 2021
  • Since the sensor nodes are randomly arranged in the region of interest, it may happen that the sensor network area is separated or there is no sensor node in some area. In addition, after the sensor nodes are deployed in the sensor network, a coverage hole may occur due to the exhaustion of energy or physical destruction of the sensor nodes. The coverage hole can greatly affect the overall performance of the sensor network, such as reducing the data reliability of the sensor network, changing the network topology, disconnecting the data link, and worsening the transmission load. Therefore, sensor network coverage hole recovery has been studied. Existing coverage hole recovery studies present very complex geometric methods and procedures in the two-step process of finding a coverage hole and recovering a coverage hole. This study proposes a method for discovering and recovering a coverage hole in a sensor network, discovering that the sensor node is a boundary node by itself, and determining the location of a mobile node to be added. The proposed method is expected to have better efficiency in terms of complexity and message transmission compared to previous methods.

Tube-Hole Center Detection Vision Algorithm for Verifying Position of Tele-Controlled Robot in Nuclear Steam Generator (원전 증기발생기 내 원격제어 로보트의 위치 검증을 위한 세관중심 검출 비젼 알고리듬)

  • 성시훈;강순주;진성일
    • Journal of the Korean Institute of Telematics and Electronics S
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    • v.35S no.2
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    • pp.137-145
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    • 1998
  • In this paper, we propose a tube-hole center detection vision algorithm verifying the position of a tele-controlled robot and providing visual information for increasing reliability and efficiency in the diagnosis of steam generator (SG) tubes in nuclear power plant. A tele-controlled robot plays a role in carrying the probe used in inspecting the integrity of SG tubes. Thus accurately locating a tele-controlled robot on the desired tube-hole center is important issue for reliability of inspection. To do this work, we have to find the tube-hole center locations from the input image. At first, we apply the three-class segmentation method modified for this application. WE extract minimum bounding rectangles (MBRs) in the theresholded binary image. Second, for discriminating between MBR by tube and MBR by noise, we introduce the MBR rejection rules as knowledge-based rule set. MBRs are divided into the very dark region MBRs and the very bright region MBRs. In order to describe the region of complete tube-hole, the MBRs need a process of pairing each other. We then can find the tube-hole center from the paired MBR. For more accurately finding the tube-hole center in several sequential images, the centers of some frames need to be averaged. We tested the performance of our method using hundreds of real images.

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The Stress Analysis of the Cross Beam of the Electric Car-body according to the Change of Location and Shape of Circular Hole (원공 위치와 형상 변화에 따른 전동차 크로스 빔의 강도해석)

  • Jeon, Hyung-Yong;Sung, Rak-Won;Han, Geun-Jo
    • Journal of the Korean Society for Precision Engineering
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    • v.16 no.9
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    • pp.9-17
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    • 1999
  • This investigation is the result of the structural analysis by finite element method for optimal design of the cross beam with circular holes of the electric car-body. in order to install the air pipe and electric wire pipe that correspond signal between electric machines for the control system and to reduce the weight of the electric car-body, several circular areas from a cross beam should be taken off. What we want to perform is the optimal design of a cross beam with circular holes to posses equal stress in comparison with no hole cross beam. first, no hole cross beam as basic modal be chosen, executing the analysis, reviewing the distribution of stress and displacement at each location. several parameter should be adopted from the cross beam geometry like the location and shape of the hole to affect the maximum stress and displacement. So the analysis was executed by finite element analysis for finding optimal design parameter to the change of the location and shape of the circular hole. finally, the optimal design of the cross beam with circular holes was obtained and the maximum equivalent stress was compared with no hole cross beam at each location.

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Adjacent Matrix-based Hole Coverage Discovery Technique for Sensor Networks

  • Wu, Mary
    • Journal of the Korea Society of Computer and Information
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    • v.24 no.4
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    • pp.169-176
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    • 2019
  • Wireless sensor networks are used to monitor and control areas in a variety of military and civilian areas such as battlefield surveillance, intrusion detection, disaster recovery, biological detection, and environmental monitoring. Since the sensor nodes are randomly placed in the area of interest, separation of the sensor network area may occur due to environmental obstacles or a sensor may not exist in some areas. Also, in the situation where the sensor node is placed in a non-relocatable place, some node may exhaust energy or physical hole of the sensor node may cause coverage hole. Coverage holes can affect the performance of the entire sensor network, such as reducing data reliability, changing network topologies, disconnecting data links, and degrading transmission load. It is possible to solve the problem that occurs in the coverage hole by finding a coverage hole in the sensor network and further arranging a new sensor node in the detected coverage hole. The existing coverage hole detection technique is based on the location of the sensor node, but it is inefficient to mount the GPS on the sensor node having limited resources, and performing other location information processing causes a lot of message transmission overhead. In this paper, we propose an Adjacent Matrix-based Hole Coverage Discovery(AMHCD) scheme based on connectivity of neighboring nodes. The method searches for whether the connectivity of the neighboring nodes constitutes a closed shape based on the adjacent matrix, and determines whether the node is an internal node or a boundary node. Therefore, the message overhead for the location information strokes does not occur and can be applied irrespective of the position information error.

Topology Optimization of Muffler Hole using Genetic Algorithm (유전자 알고리즘을 이용한 머플러 구멍 위상최적설계)

  • Wang, Semyung;Dikec, Altay;Hwang, Insoo;Kwon, Byoungha
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2003.05a
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    • pp.1205-1205
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    • 2003
  • Rotary compressors are one of the most important parts of air-conditioners in the industry This device usually has noise problems during the circulation process of the refrigerant and muffler is used for the noise reduction. The acoustic performance of the muffler depends on its shape and its hole locations on the upper surface. Therefore finding the optimum location of the muffler holes is a topic of increasing importance in the compressor industry. In this research the optimization of the muffler hole locations and the importance of the resonator cavity on the lower surface of the muffler in acoustic point of view is studied. At first, the topology optimization for the 2 hole muffler is performed based on a model without resonator cavity by using genetic algorithm. The 2 hole muffler's acoustic analysis and experiment results are matching, however, the optimized model's results are not. By adding the resonator cavity and also by changing the cavity shape, the acoustic analysis and experiment result comparison is Performed for different cavity shapes. The topology optimization of the revised model with cavity is carried out for noise reduction. Finally, the optimized design is produced and tested for validation.

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Approximate Optimization of the Steel Wheel's Disc Hole (스틸휠 디스크 홀의 근사최적화)

  • Kim, Woo-Hyun;Cho, Jae-Seng;Yoo, Wan-Suk;Lim, O-Kaung
    • Proceedings of the KSME Conference
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    • 2003.04a
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    • pp.570-573
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    • 2003
  • Wheels for passenger car support the car weight with tires. and they transmit rolling and braking power into the ground. Whittliing away at wheel weight is more effective to boost fuel economy that lighting vehicle body structure. A shape of hole in disk is optimized for minimizing the weight of steel wheel. Pro/ENGINEER program is used for formulating the design model. and ANSYS package is selected for analyzing the design model. It has difficulties 10 interface these commercial software directly. For combining both programs. response surface methodology is applied to construct approximation functions for maximum stresses and maximum displacements are obtained by full factorial design of five levels. This steel wheel is modeled in 14-inch diameter of rim. and wide parameter of hole in disk is only selected as design variable for reducing the weight of steel wheel. PLBA(Pshenichny·Lim-Belegundu_arora) algorithm. which uses the second-order information in the direction finding problem and uses the active set strategy. is used for solving optimization problems.

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Effect of chemical doping on heterostructured Fe-based superconductor Sr2VO3FeAs

  • Ok, Jong Mok;Na, Se Woong;Kim, Jun Sung
    • Progress in Superconductivity and Cryogenics
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    • v.20 no.1
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    • pp.28-31
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    • 2018
  • Phase diagrams of electron- and hole-doped $Sr_2VO_3FeAs$ are investigated using Co and Mn substitution at Fe site. Metallic nature survives only for Co (electron) doping, not for Mn (hole) doping. The conductivity of $Sr_2VO_3(Fe,M)As$ (M=Mn,Co) is sensitive to the structural modification of FeAs microstructure rather than carrier doping. This finding implies that the FeAs layer plays a dominant role on the charge conduction, thus the $SrVO_3$ layers should be considered as an insulating block. Also, we found that the superconductivity is rapidly suppressed by both dopants. This result is different from the conventional behavior that superconductivity is induced by doping in the most of Fe pnictides. Our finding strongly supports the uniqueness of $Sr_2VO_3FeAs$ among the Fe pnictide superconductors.