• Title/Summary/Keyword: 평형 위치

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Tolerance Analysis for Natural Frequencies of Multi-body Systems in Dynamic Equilibrium State (다물체계의 평형위치에서 고유진동수에 대한 공차해석)

  • Eom, Seung-Man;Choi, Dong-Hwan;Yoo, Hong-Hee
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2006.11a
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    • pp.95-100
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    • 2006
  • Tolerance analysis method for natural frequencies of multi-body systems having a equilibrium position is suggested in this paper. To perform the tolerance analysis, the Monte-Carlo Method is conventionally employed. However, the Monte-Carlo Method has some weakness; spending too much time for analysis and having a low accuracy and hard to converge in the numerical unstable area. To resolve these problems, a tolerance analysis method is suggested in this paper. Sensitivity equations of natural frequencies are derived at the equilibrium position. By employing the sensitivity information of mass, damping and stiffness matrices, the sensitivity of natural frequencies can be calculated.

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Design of a Variable Structure Controller with Nonlinear Fuzzy Sliding Surgaces (비선형 퍼지 슬라이딩면을 갖는 가변 구조 제어기의 설계)

  • 이희진;강형진;김정환;박민용
    • Journal of the Korean Institute of Intelligent Systems
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    • v.8 no.5
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    • pp.21-28
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    • 1998
  • This study develops a variable structure controller using the time-varying nonlinear sliding surface instead of the fixed sliding surface, which has been the robustness against parameter variations and extraneous disturbance during the reaching phase. By appling TS fuzzy algorithm to the regulation of the rionlinear sliding surface, the reaching time of the system trajectory is faster than the fixed method. This proposed scheme has better performance than the conventional method in reaching time, parameter variation and extraneous disturbance. To demonstrate its performance, the proposed control algorithm is applied to a rotational inverted pendulum.

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Tolerance Analysis for Natural Frequencies of Multi-body Systems in Dynamic Equilibrium State (다물체계의 평형위치에서 고유진동수에 대한 공차해석)

  • Eom, Seung-Man;Choi, Dong-Hwan;Yoo, Hong-Hee
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.17 no.1 s.118
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    • pp.65-71
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    • 2007
  • Tolerance analysis method for natural frequencies of multi-body systems having a equilibrium position is suggested in this paper. To perform the tolerance analysis, the Monte-Carlo Method is conventionally employed. However, the Monte-Carlo Method has some weakness; spending too much time for analysis and having a low accuracy and hard to converge in the dynamical unstable area. To resolve these problems, a tolerance analysis method is suggested in this paper. Sensitivity equations of natural frequencies are derived at the equilibrium position. By employing the sensitivity information of mass, damping and stiffness matrices, the sensitivity of natural frequencies can be calculated.

Steady-state Equilibrium Analysis of a Multibody System Driven by Constant Generalized Speeds (일정 일반속력으로 구동되는 다물체계의 정상상태의 평형해석)

  • Choi, D.H.;Park, J.H.;Yoo, H.H.
    • Proceedings of the KSME Conference
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    • 2001.06b
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    • pp.465-470
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    • 2001
  • This paper presents an algorithm which seeks steady-state equilibrium positions of constrained multibody systems driven by constant generalized speeds. Since the relative coordinates are employed, the constraint equations at cut joints are incorporated into the formulation. The proposed algorithm leads to nonlinear equations that need to be solved iteratively. This algorithm should satisfy both types of conditions: the force equilibrium equations and the kinematic constraint equations. To verify the effectiveness of the proposed algorithm, two numerical examples are solved and the results are compared with those of a commercial program. This method, compared to the conventional method of using dynamic analysis, has the advantage of computational efficiency and stability.

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3-Phase Unbalance Control for H-Bridge Multilevel Inverter with Faulty Power Cells (H-브릿지 멀티레벨 인버터 Power Cell 고장시의 3상 불평형 제어)

  • Park, Young-Min;Lee, Se-Hyun;Yoo, Ji-Yoon
    • Proceedings of the KIPE Conference
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    • 2007.07a
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    • pp.384-386
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    • 2007
  • 본 논문은 H-브릿지 멀티레벨 인버터 Power Cell 고장시의 3상 불평형 제어 방법을 제안하였다. 전동기 구동용 인버터 시스템에서 3상 출력 선간 전압이 평형이면 운전이 가능하다. 따라서 고장이 발생한 Power Cell만 Bypass 시키고 불평형 상전압 위상을 변경하여 3상 출력 선간 전압을 평형으로 유지하면 출력 전압 감소를 최소화하면서 운전하는 것이 가능하다. 제안된 방법은 옵셋 전압을 이용한 전압 변조 개념을 3상 불평형 제어에 확대 적용한 것으로, Power Cell의 고장 위치와 수량에 관계없이 상전압의 실시간 불평형 제어를 이용한 인버터의 최대 출력 전압을 이용할 수 있다는 장점이 있으며, 13레벨로 구성된 H-브릿지 멀티레벨 인버터 시험을 통해 제안된 방법의 타당성과 신뢰성을 입증하였다.

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Real-Time Collision-Free Trajectory Control of Nonlinear Dynamic Manipulator Control Using DNP Controller (DNP 제어기에 의한 비선형 동적 매니퓰레이터의 실시간 경로 제어)

  • Cho, Hyun-Seob
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.11 no.3
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    • pp.835-840
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    • 2010
  • This study develops a variable structure controller using nonlinear surface instead of the fixed, which has been the robustness against parameter variations and extraneous disturbance during the reaching phase. reaching time of the system trajectory is faster than the fixed method. This proposed scheme has better performance than the conventional method in reaching time, parameter variation and extraneous disturbance. The effectiveness of the proposed control scheme is verified by simulation results.

The switching method for Voltage Balance of Capacitor in a Multi-level Inverter (멀티레벨 인버터의 커패시터 전압 균형을 위한 스위칭 기법)

  • Wang, Zhi-Ming;Park, Byoung-Woo;Lee, Sang-Hyeok;Park, Sung-Jun
    • Proceedings of the KIPE Conference
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    • 2012.07a
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    • pp.45-46
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    • 2012
  • 본 논문에서는 멀티레벨 인버터에서 발생하는 DC Link 단의 커패시터 불 평형 문제를 해결하고자 새로운 DC 전압 균형을 위한 스위칭 방식에 대해 제안한다. 제안한 방식은 DC-Link 단에 위치한 각각의 커패시터들의 전압을 센싱하고 이를 PI제어를 통해 스위칭 신호를 제어함으로써 각각의 커패시터에 걸리는 전압을 균일하게 만듦으로써, 커패시터단의 전압 불 평형을 개선하였으며, 이를 3상 2레벨 멀티-레벨 인버터를 이용한 시뮬레이션 결과를 통해 본 논문의 타당성을 검증하였다.

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Determination of the Position and Velocity of the Solid-Liquid Interface During Directional Solidification of Metals based on Guided Ultrasonic Waves (유도초음파를 이용하여 금속의 방향성 고체화과정에서 고체-액체 경계면의 위치와 속도결정)

  • 김태진;슈마크텔미샤엘;그릴볼프강;쉬벤부쉬안드레;찜머만게르하르트
    • The Journal of the Acoustical Society of Korea
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    • v.17 no.2
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    • pp.79-83
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    • 1998
  • 높은 온도에서 금속물질이 응고되는 동안에 물질의 구조는 결정성장속도비율에 따 라 크게 좌우된다. 유도초음파를 기초로 한 펄스-에코 초음파실험기술과 함께 고체-액체 경 계면의 위치와 속도를 실시간으로 측정할 수 있어 고체화되는 동안의 용광로 파라메터들을 조절하는데 사용될 수 있다. 실험은 Bridgman형의 용광로에서 CuMn-막대시료에 대하여 서로 다른 냉각비율로 수행되었다. 열적평형상태에서 경계면의 위치에 대한 측정분해능은 약10㎛이다.

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Dynamic Equilibrium Position Prediction Model for the Confluence Area of Nakdong River (낙동강 합류부 삼각주의 동적 평형 위치 예측 모델: 감천-낙동강 합류점 중심 분석 연구)

  • Minsik Kim;Haein Shin;Wook-Hyun Nahm;Wonsuck Kim
    • Economic and Environmental Geology
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    • v.56 no.4
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    • pp.435-445
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    • 2023
  • A delta is a depositional landform that is formed when sediment transported by a river is deposited in a relatively low-energy environment, such as a lake, sea, or a main channel. Among these, a delta formed at the confluence of rivers has a great importance in river management and research because it has a significant impact on the hydraulic and sedimentological characteristics of the river. Recently, the equilibrium state of the confluence area has been disrupted by large-scale dredging and construction of levees in the Nakdong River. However, due to the natural recovery of the river, the confluence area is returning to its pre-dredging natural state through ongoing sedimentation. The time-series data show that the confluence delta has been steadily growing since the dredging, but once it reaches a certain size, it repeats growth and retreat, and the overall size does not change significantly. In this study, we developed a model to explain the sedimentation-erosion processes in the confluence area based on the assumption that the confluence delta reaches a dynamic equilibrium. The model is based on two fundamental principles: sedimentation due to supply from the tributary and erosion due to the main channel. The erosion coefficient that represents the Nakdong River confluence areas, was obtained using data from the tributaries of the Nakdong River. Sensitivity analyses were conducted using the developed model to understand how the confluence delta responds to changes in the sediment and water discharges of the tributary and the main channel, respectively. We then used annual average discharge of the Nakdong River's tributaries to predict the dynamic equilibrium positions of the confluence deltas. Finally, we conducted a simulation experiment on the development of the Gamcheon-Nakdong River delta using recorded daily discharge. The results showed that even though it is a simple model, it accurately predicted the dynamic equilibrium positions of the confluence deltas in the Nakdong River, including the areas where the delta had not formed, and those where the delta had already formed and predicted the trend of the response of the Gamcheon-Nakdong River delta. However, the actual retreat in the Gamcheon-Nakdong River delta was not captured fully due to errors and limitations in the simplification process. The insights through this study provide basic information on the sediment supply of the Nakdong River through the confluence areas, which can be implemented as a basic model for river maintenance and management.

The Short-term Safety Factor Considering Passive Resistance Effect of Bar Anchor Based on Smart Construction (스마트 건설기반의 강봉앵커 수동저항 효과를 고려한 단기 안전율)

  • Donghyuk Lee;Duhyun Baek
    • Journal of the Korean GEO-environmental Society
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    • v.25 no.4
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    • pp.29-35
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    • 2024
  • This is an analytical study to confirm the passive resistance effect before post-tensioning of steel bar anchors. When using a steel bar as a permanent anchor, if displacement occurs within the slope even before the head load is applied, the displacement is suppressed by the passive resistance caused by the interaction between the steel bar, grout, and surrounding soil. Accordingly, the shape of the failure surface and changes in the safety factor were examined using limit equilibrium analysis and finite element analysis targeting sites where steel bar anchors were actually applied. It was found that the safety factor of the slope reinforced with steel bar anchors is 2.02 using finite element analysis, which is about 5.9% smaller than 2.14 using limit equilibrium analysis. Also, the location of the failure surface was found to be deeper compared to the unreinforced slope. Likewise, the factor of safety has a 153% and 163% increase using finite element method and limit equilibrium analysis, respectively. In addition, the maximum displacement occurs in the lower unreinforced section within the slope, and the displacement is found to be reduced by 42 to 83% at the location where the steel bar anchors are installed.