• Title, Summary, Keyword: 시스템다이나믹스

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Examination on the Maximum-Cp Control of Wind Turbine by Sliding Mode Control (슬라이딩 모드제어 기법을 이용한 풍력 터빈의 최대 출력 제어 방법에 대한 검토)

  • Shin, Yun-Ho;Moon, Seok-Jun;Nam, Yong-Yun;Kim, Chang-Hyun;Ryu, Ji-June
    • New & Renewable Energy
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    • v.7 no.3
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    • pp.74-82
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    • 2011
  • Because concern on the problem of the limited energy is growing and the wind energy is considered as one of the biggest solutions, the researches on the wind energy and turbine are accomplished vigorously. The simulation tools on the non-linear characteristics of wind turbine system are various and it could describe the non-linear characteristics well but, the tool and methodology to apply non-linear control theory rarely exist. In this paper, the application procedure of sliding mode control theory to 2-DOF non-linear wind turbine system is suggested and the application results of it are also shown as compared with a torque loop control theory.

Application of System Dynamics Methodology for Comprehensive Analysis of the Water Business System (수도시스템 사업성과의 통합적 분석을 위한 시스템 다이나믹스 방법론 적용)

  • Lee, Sangeun;Park, Hyeyeon;Park, Heekyung
    • Journal of Korean Society of Water and Wastewater
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    • v.21 no.1
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    • pp.65-73
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    • 2007
  • To consider business-based requirements beyond the existing roles of water supply, water utilities need enough methodology to integrate lots of related issues and to introduce effective decision-makings. On these grounds, this study modeled and simulated water business system using system dynamics approach. It is expected that formalised model can describe the actual system structurally and statistically, help utilities to predict their business performance and make decisions to solve chronic issues. Moreover, the case study of Y city gave political measures objectively and practically.

Subsynchronous Vibration Behavior of Turbocharger Supported by Semi Floating Ring Bearing (세미 플로팅 링 베어링으로 지지된 터보차저의 Subsynchronous 진동 특성)

  • Lee, Donghyun;Kim, Youngcheol;Kim, Byungok;Ahn, Kookyoung;Lee, Youngduk
    • The KSFM Journal of Fluid Machinery
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    • v.20 no.1
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    • pp.15-20
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    • 2017
  • The small turbocharger for the automotive application is designed to operate up to 200,000 rpm to increase system efficiency. Because of high rotation speed of turbocharger, floating ring bearing are widely adopted due to its low friction loss and high rotordynamic stability. This paper presents a linear and nonlinear analysis model for a turbocharger rotor supported by a semi-floating ring bearing. The rotordynamic model for the turbocharger rotor was constructed based on the finite element method and fluid film forces were calculated based on the infinitely short bearing assumption. In linear analysis, we considered fluid film force as stiffness and damping element and in nonlinear analysis, the fluid film force was calculated by solving the time dependent Reynolds equation. We verified the developed theoretical model by comparing to modal test results of test rotors. The analysis results show that there are two unstable modes, which are conical and cylindrical modes. These unstable modes appear as sub-synchronous vibrations in nonlinear analysis. In nonlinear analysis, frequency jump phenomenon demonstrated when vibration mode is changed from conical mode to cylindrical one. This jump phenomenon was also demonstrated in the test. However, the natural frequency measured in the test differs from those obtained using nonlinear analysis.

Supply Contract Intelligence : The Impact of Stockout and Overstock Experiences Using System Dynamics Simulation Model (공급사슬지능 : 시스템 다이나믹스를 이용한 재고 과부족 경험이 공급사슬에 미치는 영향 분석)

  • Noh, Yonghwi;Choi, Donghyun;Rha, Jin Sung;Suh, Yongkee
    • Journal of Intelligence and Information Systems
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    • v.19 no.2
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    • pp.21-38
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    • 2013
  • The purpose of this study is to investigate the influence of behavioral factors (buyer's tendency to reflect stockout and overstock experiences in ordering decision) on the supply chain performance. This study employs system dynamics to examine the influence of these behavioral factors derived from the interview with several representatives of retailers in South Korea. The results show that different contract can bring different performance (total profit, seller's profit, buyer's profit, order quantity, sales quantity, overstock, and stockout). The results also suggest that these behavioral factors play a significantly influential role in the performance of supply contract. These results imply that supply contract should be established based on the analysis of behavioral factors of supply chain participants.

Analyzing Effects of Transparency on a Water Business Case Using System Dynamics (시스템 다이나믹스를 이용한 투명성의 수도사업에 대한 영향 분석)

  • Lee, Sangeun;Kim, Hyunok;Park, Heekyung
    • Journal of Korean Society of Water and Wastewater
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    • v.20 no.4
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    • pp.605-616
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    • 2006
  • This study focused on analyzing effects of transparency on the water system specifically and quantitatively. It was observed that transparency can give a water utility considerable motives for improving its performance and make the service price meet the production cost. System simulation made sure that these functions of transparency will eventually result in the better service for customers and the more favorable finance for a water utility. Results of this study can help some decision makers and utilities to sort out positive countermeasure for improving transparency.

Reviewing Contract of the Buenosaires Water Concession Case with System Dynamics (시스템 다이나믹스를 이용한 부에노스아이레스 수도사업 양여계약사례의 고찰)

  • Lee, Sangeun;Cha, Donghoon;Park, Heekyung
    • Journal of Korean Society of Water and Wastewater
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    • v.20 no.1
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    • pp.104-114
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    • 2006
  • Recently, the PPP (Public-Private-Participate) program on water and wastewater services in Korea has been under an active debate. However, the controversy has reached the limits of getting more valuable implications from past foreign experience beyond conceptual and/or qualitative case studies. This paper analyze scientifically and quantitatively the Buenos Aires Water Concession Project focused on propriety of the contract using system dynamics modeling. The results show that Buenos Aires's Project has several problems in the contract phase even though Argentina government spent much time to design it. Analysis results suggest that estimation of K factor considering delay effect and future uncertainty, reduction of the first fixed terms of contract, etc., are needed for a proper contract.

Dynamic terminal sliding mode control with no singularity (특이점을 가지지 않는 다이나믹 터미널 슬라이딩 모드 제어)

  • Seo, Sang-Bo;Shim, Hyung-Bo;Seo, Jin-Heon
    • Proceedings of the KIEE Conference
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    • pp.125-126
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    • 2007
  • 이 논문에서는 제어 가능한 선형시스템에 대한 다이나믹 터미널 슬라이딩 모드 제어기를 설계하고자 한다. 제안된 터미널 슬라이딩 모드구조와 제어기는 추가된 다이나믹스의 스캐일링을 통해 설계되며, 추가된 다이나믹스는 모든 상태변수들이 원점에 도달한 후에야 원점에 도달하므로 특이점을 가지지 않게 된다. 그리고 전체시스템의 유한시간 안정화는 유한시간 안정에 관한 리아프노프 함수를 이용하여 증명할 수 있다.

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