• 제목/요약/키워드: loading platform

검색결과 137건 처리시간 0.026초

무게-가변형 드론을 위한 동역학 기반 시뮬레이터 개발 (Development of Simulator for Weight-Variable Type Drone Base on Kinetics)

  • 백금봉;김정환;김식
    • 대한임베디드공학회논문지
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    • 제15권3호
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    • pp.149-157
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    • 2020
  • Regarding previously-developed drone simulators, it was easy to check their flight stability or controlling functions based on the condition that their weight was fixed from the design. However, the drone is largely classified into two types that is the one with the fixed weight whose purpose is recording video with camera and racing and another is whole weight-variable during flight with loading the articles for delivery and spraying pesticide though the weight of airframe is fixed. The purpose of this thesis is to analyze the structure of drone and its flight principle, suggest dynamics-model-based simulator that is capable of simulating weight-variable drone and develop the simulator that can be used for designing main control board, motor and transmission along the application of weight-variable drone. Weight-variable simulator was developed by using various calculation to apply flying method of drone to the simulator. First, ground coordinate system and airframe-fixing coordinate system were established and switching matrix of those two coordinates were made. Then, dynamics model of drone was established using the law of Newton and moment balance principle. Dynamics model was established in Simulink platform and simulation experiment was carried out by changing the weight of drone. In order to evaluate the validity of developed weight-variable simulator, it was compared to the results of clean flight public simulator against existing weight-fixed drone. Lastly, simulation test was performed with the developed weight-variable simulation by changing the weight of drone. It was found out that dynamics model controlled various flying positions of drone well from simulation and the possibility of securing the optimum condition of weight-variable drone that has flying stability and easiness of controlling.

Interfacing Silicate Layer Between MoO3 Ribbon and Pt Metaldots Boosts Methanol Oxidation Reaction

  • Lee, Dohun;Jeong, Juwon;Manivannan, Shanmugam;Kim, Kyuwon
    • Journal of Electrochemical Science and Technology
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    • 제11권3호
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    • pp.273-281
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    • 2020
  • Constructing and making highly active and stable nanostructured Pt-based catalysts with ultralow Pt loading are still electrifying for electrochemical applications such as water electrolysis and fuel cells. In this study, MoO3 ribbons (RBs) of few micrometer in length is successfully synthesized via hydrothermal synthesis. Subsequently, 3-dimentional (3D)-silicate layer for about 10 to 15 nm is introduced via chemical deposition onto the pre-formed MoO3 RBs; to setup the platform for Pt metaldots (MDs) deposition. In comparison with the bare MoO3 RBs, the MoO3-Si has served as a efficient solid-support for stabilizing and accommodating the uniform deposition of sub-2 nm Pt MDs. Such a structural design would effectively assist in improving the electronic conductivity of a fabricated MoO3-Si-Pt catalyst towards MOR; the interfaced, porous and 3D silicate layer has assisted in an efficient mass transport and quenching the poisonous COads species leading to a significant electrocatalytic performance for MOR in alkaline medium. Uniformly decorated, sub-2 nm sized Pt MDs has synergistically oxidized the MeOH in association with the MoO3-Si solid-support hence, synergistic catalytic activity has been achieved. Present facile approach can be extended for fabricating variety of highly efficient Metal Oxide-Metal Nanocomposite for energy harvesting applications.

LTE 망을 위한 에이전트-서버 기반의 프로토콜 분석기 (Agent-Server based Protocol Analyzer for LTE Network)

  • 피준일;이락규;임종태;복경수;유재수
    • 한국콘텐츠학회논문지
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    • 제11권10호
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    • pp.30-40
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    • 2011
  • 최근 무선 통신 기술의 발전과 함께 스마트 폰 사용자의 급증으로 차세대 이동 통신에 대한 요구가 증가하고 있다. 차세대 이동통신 플랫폼을 빠른 시간 내에 효과적으로 구축하기 위해서는 프로토콜 개발 단계부터 안정화 단계까지 프로토콜의 검증 및 분석을 위한 지원도구가 필요하다. 따라서 본 논문에서는 차세대 이동통신 플랫폼의 선두 주자인 LTE 망을 위한 프로토콜 분석기를 제안한다. 제안하는 분석기는 연동 메시지를 XML 메타데이터로 기술하여 분석 시 활용한다. 또한, 디코더 라이브러리 로딩 기능을 이용하여 LTE 망에 적용된 인코딩 메시지에 대한 분석이 가능하다. 제안하는 분석기는 자체 설계된 LTE 망과의 연동 테스트를 통해 우수성을 검증한다.

웹 기반 3차원 의료모델 시각화 시스템 (Web based 3-D Medical Image Visualization System on the PC)

  • 김남국;이동혁;김종효;강흥식;민병구;김영호
    • 대한의용생체공학회:학술대회논문집
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    • 대한의용생체공학회 1997년도 추계학술대회
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    • pp.201-205
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    • 1997
  • With the recent advance of Web and its associated technologies, information sharing on distribute computing environments has gained a great amount of attention from many researchers in many application areas, such as medicine, engineering, and business. One basic requirement of distributed medical consultation systems is that geographically dispersed, disparate participants are allowed to exchange information readily with each other. Such software also needs to be supported on a broad range of computer platforms to increase the software's accessibility. In this paper, the development of world-wide-web based medical consultation system or radiology imaging is addressed to provide the platform independence and great accessibility. The system supports sharing of 3-dimensional objects. We use VRML (Virtual Reality Modeling Language), which is the de-facto standard in 3-D modeling on the Web. 3-D objects are reconstructed from CT or MRI volume data using a VRML format, which can be viewed and manipulated easily in Web-browsers with a VRML plug-in. A Marching cubes method is used in the transformation of scanned volume data set to polygonal surfaces of VRML. A decimation algorithm is adopted to reduce the number of meshes in the resulting VRML file. 3-D volume data are often very large-sized, and hence loading the data on PC level computers requires a significant reduction of the size of the data, while minimizing the loss of the original shape information. This is also important to decrease network delays. A prototype system has been implemented (http://netopia.snu.ac.kr/-cyber/). and several sessions of experiments are carried out.

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非線形 케이블 有限要素에 관한 硏究 (A Study on a Nonlinear Cable Finite Element)

  • 장승필;박정일
    • 한국해안해양공학회지
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    • 제1권1호
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    • pp.93-101
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    • 1989
  • 본 논문에서는 가이드 타워, 텐션 레그 프랫폼, 무어링 부이, 해저 케이블, 사장교, 현수교, 케이블 루프 등과 같은 해상 및 육상 구조물의 유한요소 모델에 사용하기 위한 기하학적 비선형 케이블 요소를 연구 제시하였으며, 케이블 요소는 평면내에서 임의의 하중과 기하형상을 갖는 케이블에 대한 탄성현수 케이블 이론으로부터의 적합방정식과 연성행렬을 직접 이용하여 유도하였다. 또한, 유도된 케이블 유한요소에 근거하여, 케이블 부재를 사용하는 구조물들의 유한요소 해석을 위해 전산 프로그램을 개발하였으며, 시간영역 동적 해석을 위해 뉴마크-베타의 직접적분법을 사용하였고, 각 시간간격에서의 비선형 평형방정식 및 적합방정식을 풀기 위한 방법으로서 뉴톤-랩슨의 반복법을 사용하였다. 이상과 같이 개발된 전산 프로그램을 이용하여 케이블 부재에 대한 정적 및 동적 해석을 수행한 후 그 결과를 분석ㆍ고찰하여 보았다.

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DSP 기반 초소형 수중 음향통신 모뎀 (DSP-Based Micro-Modem for Underwater Acoustic Communications)

  • 이동수;이상민;박성준
    • 한국통신학회논문지
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    • 제39C권3호
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    • pp.275-281
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    • 2014
  • 최근 들어 연근해와 내수면에서 수중 자원의 효과적 개발과 보존을 위해 다양한 수중 응용 시스템 발굴 및 활용의 필요성이 증대되고 있다. 이에 본 논문에서는 근거리 수중 이동통신 시스템, 수중 센서네트워크 시스템 등의 핵심 기술 중의 하나인 초소형 수중 음향통신 모뎀의 디지털 모듈을 연구한다. 고속 연산처리가 가능한 디지털 신호처리 프로세서를 탑재한 수중 모뎀의 디지털 모듈을 설계하고 제작하며, 개발된 하드웨어에 프레임 형성 기능과 채널부호 알고리듬들을 구현하고 실험함으로써 회로의 기능과 성능을 검증한다. 실험 결과에 따르면, 개발된 DSP 기반 디지털 모듈에서 전송속도 1 kbps의 길쌈부호 처리를 위해 필요로 하는 연산량이 DSP의 가용 연산 능력의 1% 이내에 불과하므로 개발된 하드웨어 플랫폼에 다양한 고효율 기저대역 알고리듬을 탑재함으로써 수중 모뎀의 성능 개선을 모색할 수 있다.

Design Conditions for Dolphin Berth by Tanker Fleet Analysis

  • Kang, Seok-Jin;Lee, Joong-Woo;Lee, Dong-Hyun;Kim, Hee-Jae
    • 한국항해항만학회지
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    • 제37권6호
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    • pp.647-653
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    • 2013
  • Energy acquisition due to the increase of oil price is one of the most important issues and policy for most countries. Various tankers have been built in the world and sent to the trade market. It is necessary to build the port infrastructure and facilities to give them proper services such as mooring, packing, storing, and transshipment, etc. However, the domestic guidelines or standards for design and construction for the dolphin berth among these facilities are out of date and do not meet the recent trend of tanker types. Therefore, it requires amendment on the guidelines or standards. In this study, a detailed analysis of the tanker fleet, covering 8,000 ships under operation and order to build, is made to estimate the proper PBL(Parallel Body Length) of each tanker class. After discussion and comparison on the dolphin berth design and construction codes of various countries, those are the leading countries of tanker operation and management, suggestion was made to amend on the design code. The referred codes are of Korea, Japan, UK, USA, and Canada. The analysis of tanker fleet shows the PBL as 0.45L under the normal ballast condition. In order to verify the deduced amendment on the domestic design code for dolphin berth, it was selected one of the domestic dolphin berth, located at the Yeosu oil terminal, which is almost completed to construct. The design criteria and expected tankers to moor in that terminal were analyzed and the appropriateness and countermeasure for deficiency were summarized.

On the kinematic coupling of 1D and 3D finite elements: a structural model

  • Yue, Jianguang;Fafitis, Apostolos;Qian, Jiang
    • Interaction and multiscale mechanics
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    • 제3권2호
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    • pp.192-211
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    • 2010
  • In most framed structures the nonlinearities and the damages are localized, extending over a limited length of the structural member. In order to capture the details of the local damage, the segments of a member that have entered the nonlinear range may need to be analyzed using the three-dimensional element (3D) model whereas the rest of the member can be analyzed using the simpler one-dimensional (1D) element model with fewer degrees of freedom. An Element-Coupling model was proposed to couple the small scale solid 3D elements with the large scale 1D beam elements. The mixed dimensional coupling is performed imposing the kinematic coupling hypothesis of the 1D model on the interfaces of the 3D model. The analysis results are compared with test results of a reinforced concrete pipe column and a structure consisting of reinforced concrete columns and a steel space truss subjected to static and dynamic loading. This structure is a reduced scale model of a direct air-cooled condenser support platform built in a thermal power plant. The reduction scale for the column as well as for the structure was 1:8. The same structures are also analyzed using 3D solid elements for the entire structure to demonstrate the validity of the Element-Coupling model. A comparison of the accuracy and the computational effort indicates that by the proposed Element-Coupling method the accuracy is almost the same but the computational effort is significantly reduced.

Damage and vibrations of nuclear power plant buildings subjected to aircraft crash part II: Numerical simulations

  • Li, Z.R.;Li, Z.C.;Dong, Z.F.;Huang, T.;Lu, Y.G.;Rong, J.L.;Wu, H.
    • Nuclear Engineering and Technology
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    • 제53권9호
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    • pp.3085-3099
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    • 2021
  • Investigations of large commercial aircraft impact effect on nuclear power plant (NPP) buildings have been drawing extensive attentions, particularly after the 9/11 event, and this paper aims to numerically assess the damage and vibrations of NPP buildings subjected to aircrafts crash. In Part I of present paper, two shots of reduce-scaled model test of aircraft impact on NPP were conducted based on the large rocket sled loading test platform. In the present part, the numerical simulations of both scaled and prototype aircraft impact on NPP buildings are further performed by adopting the commercial program LS-DYNA. Firstly, the refined finite element (FE) models of both scaled aircraft and NPP models in Part I are established, and the model impact test is numerically simulated. The validities of the adopted numerical algorithm, constitutive model and the corresponding parameters are verified based on the experimental NPP model damages and accelerations. Then, the refined simulations of prototype A380 aircraft impact on a hypothetical NPP building are further carried out. It indicates that the NPP building can totally withstand the impact of A380 at a velocity of 150 m/s, while the accompanied intensive vibrations may still lead to different levels of damage on the nuclear related equipment. Referring to the guideline NEI07-13, a maximum acceleration contour is plotted and the shock damage propagation distances under aircraft impact are assessed, which indicates that the nuclear equipment located within 11.5 m from the impact point may endure malfunction. Finally, by respectively considering the rigid and deformable impacts mainly induced by aircraft engine and fuselage, an improved Riera function is proposed to predict the impact force of aircraft A380.

Shear behavior of non-persistent joints in concrete and gypsum specimens using combined experimental and numerical approaches

  • Haeri, Hadi;Sarfarazi, V.;Zhu, Zheming;Hokmabadi, N. Nohekhan;Moshrefifar, MR.;Hedayat, A.
    • Structural Engineering and Mechanics
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    • 제69권2호
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    • pp.221-230
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    • 2019
  • In this paper, shear behavior of non-persistent joint surrounded in concrete and gypsum layers has been investigated using experimental test and numerical simulation. Two types of mixture were prepared for this study. The first type consists of water and gypsum that were mixed with a ratio of water/gypsum of 0.6. The second type of mixture, water, sand and cement were mixed with a ratio of 27%, 33% and 40% by weight. Shear behavior of a non-persistent joint embedded in these specimens is studied. Physical models consisting of two edge concrete layers with dimensions of 160 mm by 130 mm by 60 mm and one internal gypsum layer with the dimension of 16 mm by 13 mm by 6 mm were made. Two horizontal edge joints were embedded in concrete beams and one angled joint was created in gypsum layer. Several analyses with joints with angles of $0^{\circ}$, $30^{\circ}$, and $60^{\circ}$ degree were conducted. The central fault places in 3 different positions. Along the edge joints, 1.5 cm vertically far from the edge joint face and 3 cm vertically far from the edge joint face. All samples were tested in compression using a universal loading machine and the shear load was induced because of the specimen geometry. Concurrent with the experiments, the extended finite element method (XFEM) was employed to analyze the fracture processes occurring in a non-persistent joint embedded in concrete and gypsum layers using Abaqus, a finite element software platform. The failure pattern of non-persistent cracks (faults) was found to be affected mostly by the central crack and its configuration and the shear strength was found to be related to the failure pattern. Comparison between experimental and corresponding numerical results showed a great agreement. XFEM was found as a capable tool for investigating the fracturing mechanism of rock specimens with non-persistent joint.