• Title/Summary/Keyword: 동적평형상태

Search Result 61, Processing Time 0.033 seconds

The influence of dynamic force balance on the estimation of dynamic uniaxial compression strength (암석시료 내 동적하중 분배특성이 동적일축압축강도에 미치는 영향성에 관한 연구)

  • Oh, Se-Wook;Min, Gyeong-Jo;Park, Se-Woong;Park, Hoon;Suk, Chul-Gi;Cho, Sang-Ho
    • Explosives and Blasting
    • /
    • v.37 no.1
    • /
    • pp.14-23
    • /
    • 2019
  • It has been an always issue for the blasting or the impact analysis to consider the strength characteristics of the rock materials associate with loading rate dependency. Due to the nature of transient loading, the dynamic rock test requires a careful technique to achieve the stress equilibrium state of the specimen. In this study, to investigate the relationship between the rock dynamic strength and the stress equilibrium state, a series of dynamic uniaxial compression tests for Pocheon granite were performed. As a result, the unbalanced stress state on the specimen can lead to the premature failure on the specimen and the less estimation of dynamic strength characteristic as well as the overestimation of strain rate. Consequently, a careful consideration of rock fracture process to achieve the dynamic force balance on the specimen should be required to make an reasonable evaluation of rock dynamic strength.

Effect of Weight of Fire-protective Clothing for Physical Balance and Agility after Maximum Physical Activity (소방방화복 무게가 최대 신체활동 후 평형성과 민첩성에 미치는 영향)

  • Bang, Chang-Hoon;Huh, Man-Dong
    • Journal of the Korean Society of Hazard Mitigation
    • /
    • v.11 no.1
    • /
    • pp.45-49
    • /
    • 2011
  • The aim of study intends to investigate effect of weight of fire-protective clothing for physical balance and agility after maximum physical activity and to provide the base data for the safety of firefighter. For evaluation of static and dynamic-balance, the closed-eyes foot balance and the beam-walking were performed respectively. For evaluation of static and dynamic-agility, the whole body reaction and the side-step were carried out. This study demonstrates that after maximum physical activity, the weight of fire-protective clothing effects on physical static-balance and dynamic-agility and suggests that it could be useful for actual safety field studies of firefighters.

현지 적용을 통한 2차원 유사이동모형의 민감도분석

  • 서상원;윤병만
    • Proceedings of the Korean Society of Coastal and Ocean Engineers Conference
    • /
    • 1997.10a
    • /
    • pp.86-89
    • /
    • 1997
  • 해안의 자연지형은 흐름의 변화에 대해서 자신의 특성을 조절하는 능력을 가지고 있다. 흐름의 변화는 자연적 변화와 인위적 변화로 구분할 수 있다. 자연적 변화는 해일, 조류, 취송류 등에 의한 변화가 있다. 또한, 댐 방류량 조절 및 온배수 제트 등은 해안 흐름의 변화를 야기하며, 항만 등 수공구조물의 건설에 의해 흐름이 인위적으로 변화된다. 흐름이 변화하게 되면 이전의 동적 평형상태에 있던 해안은 수리학적 혹성, 유사특성의 변화를 초래하여 평형상태는 깨지게 된다. (중략)

  • PDF

Long-term Riverbed Change Analysis of Climate Scenario in Nakdong River using GSTARS Model (GSTARS 모형을 이용한 낙동강에서의 기후시나리오에 대한 장기하상변동 분석)

  • Lee, Jong Mun;Ahn, Jungkyu;Kim, Young Do;Kang, Boosik
    • Proceedings of the Korea Water Resources Association Conference
    • /
    • 2016.05a
    • /
    • pp.62-62
    • /
    • 2016
  • 대하천에서의 하도정비 및 보 신설 후 다양한 하천환경변화가 예상됨에 따라 각종 변화에 의해 발생할 수 있는 현상들을 예측하고 환경변화에 의한 재난을 예방하기 위한 대책수립이 절실히 요구되고 있는 실정이다. 하천에서의 하상변동은 경우에 따라 홍수위 상승, 저수 기능 감퇴, 용수와 취수 방해, 유사에 의한 오염원 확산 등의 문제를 발생시킬 수 있다. 기후변화에 따른 강우패턴의 변화로 하천 내 수리적 요소가 변화되고 그로인해 발생하는 하상 변동의 예측이 필요하다. 만일 유역의 특성이 유지된다면 하천의 동적평형상태인 정비 이전의 하천으로 돌아가려고 할 것이다. 하천이 준설로 넓어지고 깊어진 상태로 이전의 동적인 평형상태로 돌아가려고 하도가 좁아지고 얕아질 것이다. 그러나 기후변화로 인해 유역에서의 유량 및 유사량이 달라질 것으로 예상된다. 하지만 하상변동모델과 기후변화를 연계하여 하도의 변화를 비교 분석한 연구는 매우 드물다. 본 연구에서는 기후변화에 의한 유량의 변화에 따른 시나리오를 구성하고 장기간, 장구간에 걸친 하상변동 양상을 예측하였다. 준2차원 수치모형인 GSTARS를 이용하여 낙동강 상류에서 상주보 구간 사이의 기후변화 영향을 분석하고자 장기 기후시나리오를 구성하고 유사량 공식과 수류 튜브 개수에 따른 각각의 시나리오별 하상변동 양상을 예측하고 최심하상고, 횡방향에 따른 모의결과를 분석하였다.

  • PDF

Plate Type New Distributor Development for Hydraulic Motors and Pumps (유압모터 및 펌프용 판 형태의 새로운 분배기 개발)

  • Jin, Seong-Mu;Kim, Hyeong-Ui
    • 한국기계연구소 소보
    • /
    • s.18
    • /
    • pp.75-85
    • /
    • 1988
  • The distributor for hydraulic pumps or motors, particularly radial piston motors, include rotary member which has equally both surface shape for dynamic balance and two fixed members, located in both side of rotary member, which have equal surface shape for dynamic balance and circular ring which use to retain predetermined clearance between two fixed members. Rotary member must have valve part for flow-distribution and can have hydrostatic bearing for excellently dynamic balance. At least two annular steps located on said pressure plate which use in compensation of bolt expansion.

  • PDF

Dynamic Nonlinear Analysis of Ocean Cables Subjected to Wave Forces (파력을 받는 해양케이블의 동적 비선형 해석)

  • 김문영;김남일;이정렬
    • Journal of Korean Society of Coastal and Ocean Engineers
    • /
    • v.11 no.4
    • /
    • pp.173-188
    • /
    • 1999
  • Kim et al.(I999) presented a non-linear finite element formulation of spatial ocean cables using multiple noded cable elements. The initial equilibrium state of ocean cables subjected to self-weights, support motions, and current forces was determined using the load incremental method and free vibration analysis were performed considering added mass, In this paper, the methods to generate regular and irregular waves and calculate wave forces due to these waves are discussed and challenging example problems are presented in order to investigate dynamic non-linear behaviors of ocean cables subjected to wave loadings.

  • PDF

해양분야에 응용되는 고무재료

  • Gang, Seong-Rak;Na, Chang-Un
    • Rubber Technology
    • /
    • v.9 no.2
    • /
    • pp.89-95
    • /
    • 2008
  • 지금까지 고무소재는 고무만이 갖는 독특한 점탄성과 동적 평형상태에서도 연구가 가능하다는 사실 때문에 일반 산업 현장에서 뿐만 아니라 군수산업에서도 매우 폭넓게 적용되고 있다. 본 리뷰에서는 해양분야, 특히 해군에서 응용되고 있는 고무 소재들에 대해서 살펴보고, 각 응용분야에 대한 기본적인 적용기술에 대해 논의하였다.

  • PDF

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
    • /
    • 2006.11a
    • /
    • pp.95-100
    • /
    • 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.

  • PDF

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
    • /
    • v.17 no.1 s.118
    • /
    • pp.65-71
    • /
    • 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.

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
    • /
    • v.11 no.3
    • /
    • pp.835-840
    • /
    • 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.