• Title, Summary, Keyword: 시스템다이나믹스

Search Result 183, Processing Time 0.039 seconds

Analysis of Rotordynamic Design Characteristics and Vibration Reduction of an Air Turbo Compressor for Oxygen Plant (산소공장 공기터보압축기(ATC)의 회전체동역학 설계특성 분석 및 진동저감)

  • Kim, Byung-Ok;Lee, An-Sung
    • The KSFM Journal of Fluid Machinery
    • /
    • v.13 no.3
    • /
    • pp.43-48
    • /
    • 2010
  • In this study rotordynamic characteristics of an air turbo-compressor (ATC) used in oxygen plant are analyzed and its operating-speed balancing is performed to solve the vibration trouble caused by rotor unbalance. Three dimensional model of the ATC rotor is completed and then analytical FE (finite element) model, which is verified by experimental modal testing, is developed. A rotordynamic analysis includes the critical map, Campbell diagram, and unbalance response, especially considering the pedestal housings supporting tilting pad bearings. A test run of operating-speed, using tilting-pad bearing of actual use, showed that the vibration level increased very sharply as approaching the rated speed. The operating-speed balancing specified by API 684 was carried out by using influence coefficient method. The results showed that the vibrations at the bearing pedestal housings represented good levels of 0.1 mm/s. From the test run and operating-speed balancing, the analytical results, that is, critical speeds are in good agreement with the test results and unbalance responses introducing the correction masses are similar to the as-is test responses in its aspect.

System Dynamics Interpretation on Bus Scheduling Model (시스템 다이나믹스 관점에서의 버스 운영계획모형 해석)

  • Kim, Kyeong-Sik
    • The Journal of The Korea Institute of Intelligent Transport Systems
    • /
    • v.8 no.1
    • /
    • pp.1-8
    • /
    • 2009
  • This paper aims mainly to reinterpretate Optimal Bus Scheduling Model by applying System Dynamics Perspective. Traditionally, the study regarding Optimal Bus Scheduling Model stems on the linear relationshp. However, this paper attempted to convert linear relationship based Optimal Bus Scheduling Model to causal loop perspective based Model. In result, the paper present Casual Loop Diagram for Optimal Bus Scheduling Model. Furthermore, the paper also ran a simulation based on Stock & Flow Diagram for Optimal Bus Scheduling Model. The outcome was not much different from the linear relationship based Model due to the similarity of the equation applied on two models.

  • PDF

Rotordynamic Characteristics Analysis for API 610 BB5 Pump Development (API 610 BB5 펌프 개발을 위한 로터다이나믹 특성분석)

  • Kim, Byung-Ok;Lee, An-Sung;Kim, Sung-Ki
    • The KSFM Journal of Fluid Machinery
    • /
    • v.14 no.4
    • /
    • pp.38-44
    • /
    • 2011
  • This paper deals with the detail rotordynamic analysis for BB5 eight stages pump as development of API 610 BB5 type pump. Dry-run analytical model, not considering operating fluid, and wet-run analytical model, considering operating fluid are established. In addition, plain circular and pressure dam bearings are chosen and it was discussed that each bearing has an effect on dynamic characteristics of pump rotor system. A rotordynamic analysis includes the critical speed map, Campbell diagram, stability, and unbalance response. As results, it was predicted that rated speed of the pump rotor passes through 1st critical speed in dry-run condition regardless of bearings, however, it was verified that, in wet-run condition, the rotor system doesn't have critical speeds even if more than twice rated speed. Hence the resonance problem caused by the critical speeds does not happen since actual operating is in wet-run condition including operating fluid. As a result of unbalance response analysis, the pump rotor has stable vibration response at rated speed, regardless of operating fluid and the proposed bearing types.

Measurement of decoupling performance of an multi-layered underwater decoupling material (다층구조 수중 방음재의 디커플링성능 측정방법에 대한 고찰)

  • Kim, SangRyul;Kim, Jae-Seung;Kim, Jae-Ho;Ham, Il-Bae;Jeon, Jae-Jin
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
    • /
    • /
    • pp.437-444
    • /
    • 2012
  • In this paper, the measurement method of the decoupling performance of a underwater decoupling material is studied. First, the simple vibro-acoustic coupled model of a multi-layered underwater decoupling material attached to a plate is analytically derived using impedance transfer matrix. Two test methods are introduced using the theoretical expression of the simple model. One is based on the ratio of the plate vibration and the radiated pressure under impact excitation of the plate. The other is based on the reciprocity theorem and uses the ratio of the incident pressure and the plate vibration under projector excitation in water. Some measurements are carried out according to the test methods using a pulse tube. The test results show the advantages and disadvantages of two methods. It is also shown that the combination of impact and projector excitation methods may be a useful tool to evaluate the performance of a underwater decoupling material.

  • PDF

Journal Bearing Design Retrofit for Process Large Motor-Generator - Part I : Bearing Performance Analysis (프로세스 대형 모터-발전기의 저어널 베어링 설계 개선 - Part I : 베어링 성능해석)

  • Lee, An Sung
    • Tribology and Lubricants
    • /
    • v.28 no.5
    • /
    • pp.197-202
    • /
    • 2012
  • In this study, with the purpose of fundamentally improving the unbalance response vibration of a large PRT motor-generator rotor by design, a performance improvement design analysis is carried-out by retrofitting tilting pad bearings, replacing the plain partial journal bearings that were originally applied for operation at a rated speed of 1,800 rpm. In this process, a goal of the design analysis is to obtain a design solution for maximizing the direct stiffness of the bearings while satisfying the key basic lubrication performance requirements such as the minimum lift-off speed and maximum oil-film temperature. The results show that with a careful design application of tilting pad journal bearings for operation at such a relatively low speed of 1,800 rpm, direct stiffness increment of the bearings by about two times can be effectively achieved. Prevention of pad unloading is also considered in the analysis. Moreover, the designs of elliptical and offset half journal bearings are also analyzed and reviewed.

Vibration-Based Damage Detection Method for Tower Structure (타워 구조물의 진동기반 결함탐지기법)

  • Lee, Jong-Won;Kim, Sang-Ryul;Kim, Bong-Ki
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
    • /
    • /
    • pp.320-324
    • /
    • 2013
  • A crack identification method using an equivalent bending stiffness for cracked beam and committee of neural networks is presented. The equivalent bending stiffness is constructed based on an energy method for a straight thin-walled pipe, which has a through-the-thickness crack, subjected to bending. Several numerical analysis for a steel cantilever pipe using the equivalent bending stiffness are carried out to extract the natural frequencies and mode shapes of the cracked beam. The extracted modal properties are used in constructing a training patterns of a neural network. The input to the neural network consists of the modal properties and the output is composed of the crack location and size. Multiple neural networks are constructed and each individual network is trained independently with different initial synaptic weights. Then, the estimated crack locations and sizes from different neural networks are averaged. Experimental crack detection is carried out for 3 damage cases using the proposed method, and the identified crack locations and sizes agree reasonably well with the exact values.

  • PDF

Bearing and Rotordynamic Performance Analysis of a 250 kW Reduction Gear System (250 kW급 초임계 CO2 발전용 감속기의 유체 윤활 베어링 및 회전체 동역학 특성 해석)

  • Lee, Donghyun;Kim, Byungok
    • Tribology and Lubricants
    • /
    • v.32 no.4
    • /
    • pp.107-112
    • /
    • 2016
  • This paper presents a rotordynamic analysis of the reduction gear system applied to the 250 kW super critical CO2 cycle. The reduction gear system consists of an input shaft, intermediate shaft, and output shaft. Because of the high rotating speed of the input shaft, we install tilting pad bearings, rolloer bearings support the intermediate and output shafts. To predict the tilting pad bearing performance, we calculate the applied loads to the tilting pad bearings by considering the reaction forces from the gear. In the rotordynamic analysis, gear mesh stiffness results in a coupling effect between the lateral and torsional vibrations. The predicted Campbell diagram shows that there is not a critical speed lower than the rated speed of 30,000 rpm of the input shaft. The predicted modes on the critical speeds are the combined bending modes of the intermediate and output shaft, and the lateral vibrations dominate when compared to the torsional vibrations. The damped natural frequency does not strongly depend on the rotating speeds, owing to the relatively low rotating speed of the intermediate and output shaft and constant stiffness of the roller bearing. In addition, the logarithmic decrements of all the modes are positive; therefore all modes are stable.

Competitors' Collaboration - A System Dynamics Perspective on the Collaboration Profit Model

  • Kim, Bowon
    • Korean System Dynamics Review
    • /
    • v.2 no.1
    • /
    • pp.113-129
    • /
    • 2001
  • 본 논문을 통하여 인터넷 환경의 B2B 마켓플레이스에서 경쟁 기업들 간에 왜 그리고 어떻게 협력(Collaboration)이 가능한지 살펴본다. 시스템 다이나믹스 시뮬레이션을 활용하여 잠정적으로 도달한 결론은 경쟁 기업들의 그러한 협력이 시장 수요의 증가를 가져오고 이를 통해 증대된 이윤을 실현할 수 있을 때 그와 같은 관계가 가능하다는 것이다. 즉, 경쟁기업간 협력이 지속가능하기 위해서는 기업간 협력이 시장 수요를 확대하고 그 결과로 개별 기업이(비록 시장 점유율이 하락하는 경우가 있을지라도) 더 많은 절대적인 이윤을 얻을 수 있어야 한다. 경우에 따라서는 파이를 분배하기 전에 파이의 절대적인 크기를 키우는 것이 좋다는 것과 유사한 논리이다.

  • PDF

Balanced Scorecard using System Dynamics for Evaluating IT Investment (IT 투자 평가를 위한 시스템 다이나믹스를 활용한 밸런스스코어카드)

  • Baek, Sung-Won;Ju, Jung-Eun;Koo, Sang-Hoe
    • Journal of Intelligence and Information Systems
    • /
    • v.14 no.1
    • /
    • pp.19-34
    • /
    • 2008
  • IT investment is usually very costly and takes a long time to get the results out of investment. However, most of currently available evaluation methods for IT investment are based upon short-term effects, hence their results are not fully trustworthy. In addition, those methods commonly consider only financial aspects such as ROI. For more reliable evaluation, it is necessary to consider non-financial factors such as system utilization, customer satisfaction, public relations, and so on, as well as financial factors. In this research, we propose an evaluation method that can evaluate both financial and non-financial aspects on a long-term base. For this purpose, we employed the research results developed in System dynamics and Balanced scorecard. System dynamics is useful in analyzing long term behavior of a given system, and Balanced scorecard is useful for evaluating both financial and non-financial aspects. We demonstrated the usefulness of our method by applying it to the evaluation of RFID (Radio Frequency Identification) investment in a distribution and retail industry. From this application, we found that RFID investment may not be rewarding in the short term, but is sure to be returning the income relative to its investment in the long run.

  • PDF

A Develpment of System Dynamics Model for Airport Sustainability Assessment (공항의 지속가능성 평가모형의 개발)

  • Yu, Gwang-Ui;Kim, Won-Gyu;Kim, Byeong-Jong;Kim, Mi-Gyeong
    • Journal of Korean Society of Transportation
    • /
    • v.23 no.2
    • /
    • pp.7-24
    • /
    • 2005
  • A large scale international airport is an essential ingredient of the regional and the national economy. It helps the regional and the national economy booming. On the other hand, some international airport forms a region by itself with the surrounding community, which tends to keep growing. The airport development can be viewed as a sort of regional development and its sustainability needs to be examined during both planning phase and operating phase. n this paper, a system dynamic model is proposed to access the sustainability of airport develpment and the model is applied to address the sustainability of Korea's new international airport. Incheon International Airport, develpment. The study reveals that the phase 2 facilities need to be built quickly to meet anticipated future traffic and that the air pollutants need to be reduced by 6% to keep the airport development sustainable.