• Title, Summary, Keyword: STL

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Investigation for effect of the specimen location on sound transmission loss measurement (차음성능시험에서 시편설치위치에 대한 실험적 고찰)

  • 김상렬;강현주;김재승;김현실;김봉기
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.1234-1237
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    • 2002
  • When measuring sound transmission loss (STL) in a laboratory, the specimen location in test aperture affects considerably the measuring accuracy through the influence of so-called “tunneling effect” In this paper, for a single panel and a double panel with air cavity, experimental STL evaluations on various specimen locations on test aperture were carried out to explain the phenomenon. It is shown that the difference of STL is more than 2dB especially at the low frequency region and the case of the center-located panel yielded the lower STL than that of flushing with the end of tunnel, which confirms that the tunneling effect plays an important role in STL measurement.

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Bridging the gap between CAD and CAE using STL files

  • Bianconi, Francesco
    • International Journal of CAD/CAM
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    • v.2 no.1
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    • pp.55-67
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    • 2002
  • In many areas of industry, it is desirable to have fast and reliable systems in order to quickly obtain suitable solid models for computer- aided analyses. Nevertheless it is well known that the data exchange process between CAD modelers and CAE packages can require significative efforts. This paper presents an approach for geometrical data exchange through triangulated boundary models. The proposed framework is founded on the use of STL file specification as neutral format file. This work is principally focused on data exchange among CAD modelers and FEA packages via STL. The proposed approach involves the definition of a topological structure suitable for the STL representation and the development of algorithms for topology and geometry data processing in order to get a solid model suitable for finite element analysis or other computer aided engineering purposes. Different algorithms for model processing are considered and their pros and cons are discussed. As a case study, a prototype modeler which supports an exporting filter for a commercial CAE package has been implemented.

A Study on Feature Division using Sliced Information of STL Format (STL 포맷의 단면정보를 이용한 형상분할에 관한 연구)

  • Ban, Gab-Su
    • Journal of the Korean Society of Industry Convergence
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    • v.5 no.2
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    • pp.141-146
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    • 2002
  • Stereolithography is the best known as rapid prototyping system. It uses the STL format data which is generated from CAD system. In this study, One of the main function of this developed CAM system deals with shape modification which divide a shape into two parts or more. The cross section of a STL part by a z-level is composed with nested or single polygonal closed loop. In order to make RP product, closed loops must fill with triangular facets from SSET and recover sliced triangular facets which is located normal direction to the cross sectional plane. The system is development by using Visuall C++ compiler in the environment of pentium PC. Operating system is Windows NT workstaion from Micro-Soft.

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The Study on the Reduction of Laser Scanning Path Creation Time during Jewellery Pattern Manufacturing (쥬얼리 패턴제작시 주사경로생성시간 단축에 관한 연구)

  • Kim, T.H.;Kim, S.Y.;Park, J.D.;Kim, M.J.;Jeon, E.C.
    • Korean Journal of Computational Design and Engineering
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    • v.11 no.6
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    • pp.440-446
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    • 2006
  • This study relates to the effect of forming time of injection path on the total process. The whole process can be divided into build process of forming path of injection and after treatment process. The total time required for the whole process could be reduced by reducing the forming time of injection path using SLC file to correct the problems of STL file that is the basic file format for high speed molding devices. First of all, I verify the forming time of injection path according to the conditions of STL file during the formation of injection path. And I verify problems using STL file during formation of injection path. And then I tried to solve problems of STL file by comparing between the formation time of injection path and the existing method using SLC files.

A Study on the Design of STL/TTL Link Radio System GUI Simulator for M/W Band Digital Broadcasting Relay (M/W대역 디지털 방송중계용 STL/TTL 링크 무선전송 시스템 GUI 시뮬레이터 구현에 관한 연구)

  • 이양선;강희조;김윤호
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • pp.112-115
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    • 2004
  • 본 논문에서는 M/W 방송중계용 주파수 공유방안에 관한 기초연구로써 디지털 방송중계용 STL/TTL 링크 무선전송 시스템을 모델링하고 다중경로 페이딩 채널 환경에서 시스템 특성 및 성능 분석이 가능한 M/W대 디지털 방송중계용 STL/TTL 링크 무선전송 시스템 시뮬레이터를 GUI 환경으로 구현하였다. 국내 방송 중계용의 경우 디지털화 진행이 추진되고 있는바, 본 연구에서 구현한 디지털 STL/TTL 링크 무선전송 시스템 시뮬레이터를 이용하여 향후 M/W 대역 방송중계용 주파수 재배치를 위한 채널 성능 및 간섭평가를 수행함으로써 국내 방송중계용 표준화에 기초 자료로 활용하고자 한다.

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Generating FE Mesh Automatically from STL File Model (STL 파일 모델로부터 유한 요소망 자동 생성)

  • Park, Jung-Min;Kwon, Ki-Youn;Lee, Byung-Chai;Chae, Soo-Won
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.31 no.7
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    • pp.739-746
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    • 2007
  • Recently, models in STL files are widely used in reverse engineering processes, CAD systems and analysis systems. However the models have poor geometric quality and include only triangles, so the models are not suitable for the finite element analysis. This paper presents a general method that generates finite element mesh from STL file models. Given triangular meshes, the method estimates triangles and makes clusters which consist of triangles. The clusters are merged by some geometric indices. After merging clusters, the method applies plane meshing algorithm, based on domain decomposition method, to each cluster and then the result plane mesh is projected into the original triangular set. Because the algorithm uses general methods to generate plane mesh, we can obtain both tri and quad meshes unlike previous researches. Some mechanical part models are used to show the validity of the proposed method.

STL mesh based laser scan planning system for complex freeform surfaces (STL 메쉬를 이용한 자유곡면의 레이저 측정경로 생성 연구)

  • 손석배;김승만;이관행
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.595-598
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    • 2002
  • Laser scanners are getting used more and more in reverse engineering and inspection. For CNC-driven laser scanners, it is important to automate the scanning operations to improve the accuracy of capture point data and to reduce scanning time in industry. However, there are few research works on laser scan planning system. In addition, it is difficult to directly analyze multi-patched freeform models. In this paper, we propose an STL (Stereolithography) mesh based laser scan planning system for complex freeform surfaces. The scan planning system consists of three steps and it is assumed that the CAD model of the part exists. Firstly, the surface model is approximated into STL meshes. From the mesh model, normal vector of each node point is estimated. Second, scan directions and regions are determined through the region growing method. Also, scan paths are generated by calculating the minimum-bounding rectangle of points that can be scanned in each scan direction. Finally, the generated scan directions and paths are validated by checking optical constraints and the collision between the laser probe and the part to be scanned.

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An Analysis of the Sound Transmission through a Plate Installed inside an Impedance Tube (임피던스 튜브 내에 설치된 평판의 음파투과해석)

  • Kim, Hyun-Sil;Kim, Bong-Ki;Kim, Sang-Ryul;Lee, Seong-Hyun
    • The Journal of the Acoustical Society of Korea
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    • v.34 no.3
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    • pp.219-226
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    • 2015
  • In this paper, derivation of the STL (Sound Transmission Loss) of a square plate installed in an impedance tube is discussed using an analytic method. Coupled motion of the plate vibration and acoustic field is considered. Vibration of the plate and pressure field inside the tube are expressed in terms of the infinite series of modal functions. Under the plane wave assumption, it is shown that consideration of the first few modes yields sufficiently accurate results. When the boundary of the plate is clamped, vibration mode is assumed as a multiplication of the beam modes corresponding to the crosswise directions. The natural frequencies of the clamped plate are calculated using the Rayleigh-Ritz method. It is found that the STL shows a dip at the lowest natural frequency of the plate, and increases as the frequency decreases below the natural frequency. Comparison of the result in this paper with the STL obtained by measurements and FE computations in the reference shows an excellent agreement.

Sound transmission of multi-layered micro-perforated plates in a cylindrical impedance tube (원통형 임피던스 튜브 내 다중 미세천공 판의 음향투과)

  • Kim, Hyun-Sil;Ma, Pyung-Sik;Kim, Bong-Ki;Lee, Seong-Hyun;Seo, Yun-Ho
    • The Journal of the Acoustical Society of Korea
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    • v.39 no.4
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    • pp.270-278
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    • 2020
  • In this paper, sound transmission of Micro-Perforated Plates (MPPs) installed in an impedance tube with a circular cross-section is described using an analytic method. Vibration of the plates is expressed in terms of an infinite series of modal functions, where modal function in the radial direction is given by the Bessel function. Under the plane wave assumption, a low frequency approximation is derived, and a formula for the sound transmission coefficient of multi-layered MPPs is presented using the transfer matrix method. The Sound Transmission Losses (STLs) of single and double MPPs are computed using the proposed method and compared with those done by the Finite Element Method (FEM), which shows an excellent agreement. As the perforation increases, the STL is degraded, since the STL becomes dominated by the perforation ratio rather than by vibration of the plate. The STL shows dips at natural frequencies as well as at the mass-spring-mass resonance frequency. The proposed model for the STL prediction in this study can be applied to an arbitrary number of MPPs, where each MPP may or may not have a perforation.