• 제목/요약/키워드: Mechanical modeling

검색결과 3,106건 처리시간 0.027초

Molecular Modeling and its Experimental Verification for the Catalytic Mechanism of Candida antarctica Lipase B

  • Kwon, Cheong-Hoon;Shin, Dae-Young;Lee, Jong-Ho;Kim, Seung-Wook;Kang, Jeong-Won
    • Journal of Microbiology and Biotechnology
    • /
    • 제17권7호
    • /
    • pp.1098-1105
    • /
    • 2007
  • Quantum mechanical and molecular dynamics simulation analysis has been performed on the model system for CALB (Candida antarctica lipase B) with esters to study the reaction mechanism and conformational preference of catalytic hydrolysis and the esterification reaction. Using quantum mechanical analysis, the ping-pong bi-bi mechanism was applied and energies and 3-dimensional binding configurations of the whole reaction pathways were calculated. Further molecular dynamics simulation analysis was performed on the basis of the transition state obtained from quantum mechanical study to observe the effect of structures of the substrates. Calculation results using substrates of different chain length and chiral configurations were compared for conformational preference. The calculated results showed very small influence on chain length, whereas chiral conformation showed big differences. Calculated results from molecular modeling studies have been compared qualitatively with the experimental data using racemic mixtures of (${\pm}$)-cis-4-acetamido-cyclopent-2-ene-1-ethyl acetate as substrates.

유압 구동방식 타이어 롤러를 위한 유압 시스템 회로분석 및 모델링에 관한 연구 (A Study on the Hydraulic System Circuit Analysis and Modeling of the Hydrostatic Tire Roller)

  • 김상겸;박춘식;김정하
    • 대한기계학회논문집B
    • /
    • 제27권4호
    • /
    • pp.432-439
    • /
    • 2003
  • In this research, we are trying to develop the new hydraulic driven tire roller which is conventionally operated by mechanical transmission system. The reason why we would like to develop it is that tire roller is one of the most useful machine for the road construction site and also imported totally from overseas. In this paper, we conceptualize the new hydraulic system and derive the equations of motion for dynamic analysis. And we investigate system modeling by using DAQ system. Finally, we will design the controller, which can manage the hydraulic circuit of steering and traction mechanism system. The advent of modern high-speed computers coupled with the application of high-fidelity simulation technology can be used to create “virtual prototypes of construction equipment. Tests conducted on these virtual prototypes may be used to augment actual machine testing, thereby lowering costs and shortening time to production. So, we studied tire roller to integrate development technology. In System Analysis, We formulate hydraulic driving system model and hydraulic steering system model. Also, We integrate DAQ system to acquire experimental result in real tire roller equipment.

공압 제진 시스템의 해석과 설계: I. 모델링과 전달율 계산 알고리즘 (Analysis and Design of a Pneumatic Vibration Isolation System: Part I. Modeling and Algorithm for Transmissibility Calculation)

  • 문준희;박희재
    • 한국정밀공학회지
    • /
    • 제21권10호
    • /
    • pp.127-136
    • /
    • 2004
  • This paper is the first of two companion papers concerning the analysis and design of a pneumatic vibration isolation system. The design optimization of the pneumatic vibration isolation system is required for the reduction of cost, endeavor and time, and it needs modeling and calculation algorithm. The nonlinear models are devised from the fluid mechanical expression for components of the system and the calculation algorithm is derived from the mathematical relationship between the models. It is shown that the orifice makes the nonlinear property of the transmissibility curve that the resonant frequency changes by the amplitude of excited vibration. Linearization of the nonlinear models is tried to reduce elapsed time and truncation error accumulation and to enable the transmissibility calculation of the system with multi damping chambers. The equivalent mechanical models generated by linearization clarify the function of each component of the system and lead to the linearized transfer function that can give forth to the transmissibility exactly close to that of nonlinear models. The modified successive under-relaxation method is developed to calculate the linearized transfer function.

MULTISCALE MODELING OF RADIATION EFFECTS ON MATERIALS: PRESSURE VESSEL EMBRITTLEMENT

  • Kwon, Jun-Hyun;Lee, Gyeong-Geun;Shin, Chan-Sun
    • Nuclear Engineering and Technology
    • /
    • 제41권1호
    • /
    • pp.11-20
    • /
    • 2009
  • Radiation effects on materials are inherently multiscale phenomena in view of the fact that various processes spanning a broad range of time and length scales are involved. A multiscale modeling approach to embrittlement of pressure vessel steels is presented here. The approach includes an investigation of the mechanisms of defect accumulation, microstructure evolution and the corresponding effects on mechanical properties. An understanding of these phenomena is required to predict the behavior of structural materials under irradiation. We used molecular dynamics (MD) simulations at an atomic scale to study the evolution of high-energy displacement cascade reactions. The MD simulations yield quantitative information on primary damage. Using a database of displacement cascades generated by the MD simulations, we can estimate the accumulation of defects over diffusional length and time scales by applying kinetic Monte Carlo simulations. The evolution of the local microstructure under irradiation is responsible for changes in the physical and mechanical properties of materials. Mechanical property changes in irradiated materials are modeled by dislocation dynamics simulations, which simulate a collective motion of dislocations that interact with the defects. In this paper, we present a multi scale modeling methodology that describes reactor pressure vessel embrittlement in a light water reactor environment.

볼트 체결 조건에 따른 두 판재의 동적 특성 예측 (Prediction of the Dynamic Characteristics of a Bolt-Joint Plates According to Bolting Conditions)

  • 홍상준;이동진;유정훈
    • 대한기계학회논문집A
    • /
    • 제29권9호
    • /
    • pp.1175-1182
    • /
    • 2005
  • General systems have many substructures assembled at joints. The bolted joint is generally used in assembling the mechanical parts. However, there are no effective modeling methods to analyze the dynamic characteristics of bolt jointed structure using the finite element (FE) analysis, especially in case of large area contact. Moreover, the design methods for the appropriate bolt locations and the number of bolts considering the dynamic characteristics are not guided properly. In this study, a proper modeling method is developed to simulate the dynamic characteristics of a structure with the large interfaced area using the cone frusta method and spring elements. The natural frequencies are also controlled by adjusting the bolt-joint location and the number of bolts considering relative distances in mode shapes at the interface of bolt-jointed plates. The Modeling method and the optimized design method are verified based on the experimental and the FE analysis results.

고준위 폐기물 처분장 near-field에 대한 열-역학적 민감도 분석 (Thermal-mechanical sensitivity analysis for the near-field of HLW repository)

  • 권상기;최종원;강철형
    • 터널과지하공간
    • /
    • 제13권2호
    • /
    • pp.138-152
    • /
    • 2003
  • 지하 수백미터 심부에 위치하는 고준위방사성 폐기물 처분장에서의 열-역학적 안정성 평가를 위해 FLAC3D를 이용한 3차원 해석이 수행되었다. 효과적인 해석을 위해 FISH프로그램이 작성되었으며 고성과 유성 의 시추부지에서 얻어진 지질, 암반 물성자료가 사용되었다. Factional factorial design을 적용한 실험설계를 거쳐 얻어진 응력, 온도에 대한 민감도 분석이 실시되었으며 이를 통해 처분장 안정성에 영향을 미치는 주요 설계 인자의 선정 및 인자 상호간의 영향을 분석할 수 있었다. 연구 결과 열-역학적 안정성에 가장 큰 영향을 미치는 인자는 처분공의 간격으로 나타났으며 처분터널의 간격과 완충재의 두께가 그 다음으로 주요한 인자인 것으로 나타났다.

CFD를 이용한 희박 예혼합 연소기에서의 연소 응답 모델링 (Flame Response Modeling for Lean Premixed Combustors Using CFD)

  • 김대식;이정원
    • 대한기계학회논문집B
    • /
    • 제38권9호
    • /
    • pp.773-779
    • /
    • 2014
  • 가스터빈 희박 예혼합 연소기에서 발생하는 연소 불안정 현상을 모델링하기 위해서는 화염의 동 특성에 대한 정량적, 정성적 분석이 필수적이다. 이를 위하여 화염전달함수가 전산유체역학을 통하여 모델링되었다. 기존 화염전달함수의 연구 결과로부터, 화염전달함수의 결과는 화염의 구조에 크게 의존하는 것으로 알려졌다. 본 연구에서는 실제 계측된 화염의 구조와 유사한 형상을 갖도록 열전달 조건을 최적화한 후, 동일 조건에서 화염전달함수가 모델링되었다. 화염의 형상을 정확하게 예측할 수 있다면, 이로부터 전달함수의 이득값과 위상차의 모델링 결과 역시 실험값과 유사한 거동을 확인할 수 있었다.

화원 위치 추정을 위한 베이시안 추정 기반의 모델링 및 시뮬레이션 연구 (Study on Modeling and Simulation for Fire Localization Using Bayesian Estimation)

  • 김태완;김수찬;김종환
    • 대한조선학회논문집
    • /
    • 제58권6호
    • /
    • pp.424-430
    • /
    • 2021
  • Fire localization is a key mission that must be preceded for an autonomous fire suppression system. Although studies using a variety of sensors for the localization are actively being conducted, the fire localization is still unfinished due to the high cost and low performance. This paper presents the modeling and simulation of the fire localization estimation using Bayesian estimation to determine the probabilistic location of the fire. To minimize the risk of fire accidents as well as the time and cost of preparing and executing live fire tests, a 40m × 40m-virtual space is created, where two ultraviolet sensors are simulated to rotate horizontally to collect ultraviolet signals. In addition, Bayesian estimation is executed to compute the probability of the fire location by considering both sensor errors and uncertainty under fire environments. For the validation of the proposed method, sixteen fires were simulated in different locations and evaluated by calculating the difference in distance between simulated and estimated fire locations. As a result, the proposed method demonstrates reliable outputs, showing that the error distribution tendency widens as the radial distance between the sensor and the fire increases.

Surface Mounting Device의 동역학적 모델링 및 상태 민감도 해석 (A Dynamic Modeling & State Sensitivity Analysis of the Surface Mounting Device)

  • 장진희;한창수;김정덕
    • 한국정밀공학회지
    • /
    • 제13권7호
    • /
    • pp.90-99
    • /
    • 1996
  • In the area of assembly process of micro-chips and electronic parts on the printed circuit board, surface mounting device(SMD) is used as a fundamental tool. Generally speaking, the motion of the SMD is based on the ball screw system operated by any type of actuators. The ball screw system is a mechanical transformed which converts the mechanical rotational motion to the translational one. Also, this system could be considered as an efficient motion device against mechanical backlash and friction. Therefore a dynamic modeling and state sensitivity analysis of the ball screw system in SMD have to be done in the initial design stage. In this paper, a simple mathematical dynamic model for this system and the sensit- ivity analysis are mentioned. Especially, the bond graph approach is used for graphical modeling of the dynamic system before analysis stage. And the direct differentiation method is used for the state sensit- ivity analysis of the system. Finally, some trends for the state variables with respect to the design variables could be suggested for the better design and faster operating based on the results of dynamic and state sensitivity.

  • PDF

잠수함 마스트 커버의 구조해석 및 3D 프린팅 (3D Printing and Structure Anlaysis of the Submarine Mast Cover)

  • 우재혁;차병준;진철규
    • 한국산업융합학회 논문집
    • /
    • 제26권5호
    • /
    • pp.937-943
    • /
    • 2023
  • In this study, the mast cover of submarine was reverse engineered and structural analysis was performed. In order to print with the 3D printer, the modeling was reduced to 1/5 size by applying geometric similarity. From the structural analysis results, it was found that the maximum value of equivalent stress generated in the mast cover was 180.9 MPa. This stress value occurs on the inner surface in the major axis. As a result of applying the load condition at a diving depth of 600 m, the mast cover is in a completely elastic state. The 1/5 size model printed on FDM 3D printer with PLA filament was the same as the reverse engineered modeling and it was printed in a perfect shape with no apparent defects. The 1/5 size model printed on PBF 3D printer with SUS316L powder was perfectly manufactured with no apparent defects.