• Title/Summary/Keyword: Dynamic effects

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Effects of dynamic oxygen concentrations on the development of mouse pre- and peri-implantation embryos using a double-channel gas supply incubator system

  • Lee, Seung-Chan;Seo, Ho-Chul;Lee, Jaewang;Jun, Jin Hyun;Choi, Kyoo Wan
    • Clinical and Experimental Reproductive Medicine
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    • v.46 no.4
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    • pp.189-196
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    • 2019
  • Objective: We aimed to evaluate the effects of different oxygen conditions (20% [high O2], 5% [low O2] and 5% decreased to 2% [dynamic O2]) on mouse pre- and peri-implantation development using a novel double-channel gas supply (DCGS) incubator (CNC Biotech Inc.) to alter the oxygen concentration during in vitro culture. Methods: The high-O2 and low-O2 groups were cultured from the one-cell to the blastocyst stage under 20% and 5% oxygen concentrations, respectively. In the dynamic-O2 group, mouse embryos were cultured from the one-cell to the morula stage under 5% O2 for 3 days, followed by culture under 2% O2 to the blastocyst stage. To evaluate peri-implantation development, the blastocysts from the three groups were individually transferred to a fibronectin-coated dish and cultured to the outgrowth stage in droplets. Results: The blastocyst formation rate was significantly higher in the low-O2 and dynamic-O2 groups than in the high-O2 group. The total cell number was significantly higher in the dynamic-O2 group than in the low-O2 and high-O2 groups. Additionally, the apoptotic index was significantly lower in the low-O2 and dynamic-O2 groups than in the high-O2 group. The trophoblast outgrowth rate and spread area were significantly higher in the low-O2 and dynamic-O2 groups than in the high-O2 group. Conclusion: Our results showed that a dynamic oxygen concentration (decreasing from 5% to 2%) had beneficial effects on mouse pre- and peri-implantation development. Optimized, dynamic changing of oxygen concentrations using the novel DCGS incubator could improve the developmental competence of in vitro cultured embryos in a human in vitro fertilization and embryo transfer program.

Dynamic shear modulus and damping ratio of saturated soft clay under the seismic loading

  • Zhen-Dong Cui;Long-Ji Zhang;Zhi-Xiang Zhan
    • Geomechanics and Engineering
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    • v.32 no.4
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    • pp.411-426
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    • 2023
  • Soft clay is widely distributed in the southeast coastal areas of China. Many large underground structures, such as subway stations and underground pipe corridors, are shallow buried in the soft clay foundation, so the dynamic characteristics of the soft clay must be considered to the seismic design of underground structures. In this paper, the dynamic characteristics of saturated soft clay in Shanghai under the bidirectional excitation for earthquake loading are studied by dynamic triaxial tests, comparing the backbone curve and hysteretic curve of the saturated soft clay under different confining pressures with those under different vibration frequencies. Considering the coupling effects of the confining pressure and the vibration frequency, a fitting model of the maximum dynamic shear modulus was proposed by the multiple linear regression method. The M-D model was used to fit the variations of the dynamic shear modulus ratio with the shear strain. Based on the Chen model and the Park model, the effects of the consolidation confining pressure and the vibration frequency on the damping ratio were studied. The results can provide a reference to the earthquake prevention and disaster reduction in soft clay area.

The Analytic and Experimental Research on Dynamic Characteristics of EMV System (EMV시스템의 동특성 분석을 위한 모델 및 실험적 고찰)

  • 박승현;이종화;김도중;박경석
    • Transactions of the Korean Society of Automotive Engineers
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    • v.10 no.3
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    • pp.85-92
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    • 2002
  • This paper presents the effects of design and operating parameters to meet the static and dynamic performances of the electro-mechanical valve(EMV) actuator which can provide more flexible controllability of valve events compared to conventional variable valve actuation devices. The model of the EMV system was also set up and applied to identify the dynamic behavior of the system. And the effects of external disturbances were also investigated such as cylinder pressure, armature neutral position and current supplying time effects and so on. Experiments were carried out to verify the model using the prototype actuator on test bench, it was found that there is a relatively good agreement between experimental data and modeling results. Also, the actuators meet the general engine speed range (over 6000rpm) and the variable valve event control for various VVT effects.

Dynamic Analysis of a Large Tilting Pad Journal Bearing Including the Effects of Temperature Rise and Turbulence (온도상승 및 난류효과를 고려한 대형 틸팅패드 저널베어링의 동특성 해석)

  • 하현천;김경웅
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.19 no.2
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    • pp.313-321
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    • 1995
  • The effects of the temperature rise and the turbulence are very important factors to predict the accurate performance of a large tilting pad journal bearing. In this study, the dynamic characteristics of a large tilting pad journal bearing are analyzed, taking into account the three dimensional variation of lubricant viscosity and turbulence. The effects of the temperature rise and the turbulence on the stiffness and damping coefficients are investigated in comparison with the results from the laminar or isothermal theory. The stiffness and damping coefficients increase due to the turbulence but decrease due to the temperature rise. The results show that the effects of both the temperature rise and turbulence must be considered simultaneously in order to predict the dynamic characteristics of a large tilting pad journal bearing more accurately.

Simple analysis on induction motor dynamic performances by time constant parameter (유도전동기의 동특성해석에 있어서의 Time constant parameter에 의한 간이해석법)

  • 황영문
    • 전기의세계
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    • v.31 no.2
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    • pp.126-131
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    • 1982
  • Induction motors are known to cause voltage dip, oscillating torque and inrush current on the dynamic period. To compensate for these undesirable effects, the prediction of dynamic performances is required. The dynamic performances are determinated by circuit time constants. From this point of view, in this paper, the dynamic equivalent circuit included only three time-constant parameters are presented. To predict more simply dynamic performances, the new characteristics time constant parameters are analyzed, and now these parameters are described as the function of circuit time constants. This paper reviews and analyzes the use of series capacitance compensations, and the use of this analysis can make simply a prediction about oscillating conditions.

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Improvement of waste landfill by dynamic compaction method (동다짐공법에 의한 쓰레기매립지반의 개량특성 분석)

  • 정하익;곽수정
    • Proceedings of the Korean Geotechical Society Conference
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    • 2002.10a
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    • pp.404-410
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    • 2002
  • Dynamic compaction is an efficient ground improvement technique for loose soils and waste landfill. The improvement is obtained by controlled high energy tamping and its effects vary with the soil properties and energy input. This study demonstrated the application of dynamic compaction method for the improvement of waste landfill in construction site. Various tests and measurements such as standard penetration test, bore hole loading test, crater settlement, ground settlement, pore water pressure were peformed during dynamic compaction field test. From the field test results, the efficiency of dynamic compaction method for the improvement of waste landfill was proved.

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A Study on the Effects of Dual Dynamic Vibration Absorber for Damped Vibration System (감쇠진동계에 부착된 복합동흡진기의 효과에 관한 연구)

  • 안찬우;최석창;김동영
    • Journal of KSNVE
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    • v.7 no.6
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    • pp.1039-1048
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    • 1997
  • This paper describes the effects of dual dynamic vibration absorbers attached to a primary vibration system with damping. The efficiency of dual dynamic vibration absorbers was investigated with the height of amplitude ratio at the resonance frequency ratio of the damped vibration system according to mass ratio, natural frequency ratio and damping ratio. The variation of amplitude ratio related to frequency ratio of primary vibration system is verified experimentally and theoretically according to dual dynamic vibration systems using computer program designed to find mutual relationship between two absorbers.

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Effects of Dynamic Soil Behaviour on Wave-Induced Seabed Response

  • Cha, D.H;Jeng, D.S;Rahman, M.S.;Sekiguchi, H.;Zen, K.;Yamazaki, H.
    • Journal of Ocean Engineering and Technology
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    • v.16 no.5
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    • pp.21-33
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    • 2002
  • In this paper, an analytical solution for the wave-induced seabed response in a porous seabed is derived. Unlike previous investigations with quasi-static soil behaviour, dynamic soil behaviour is considered in the new solution. The basic one-dimensional framework proposed by Zienkiewicz et al (1980) is extended to two-dimensional cases. Based on the analytical solution derived, the effects of dynamic soil behaviour on the wave-induced seabed response are examined. The boundary of quasi-static soil behaviour and dynamic soil behaviour is clarified, and formulated for engineering practice.

A Study on the Effects of Dynamic Vibration Absorber for Driveline with Propeller Shaft Supported by Center Bearing (센터 베어링으로 지지된 추진축을 갖는 구동계에서의 진동흡진기의 영향에 대한 연구)

  • 강영춘;임재환;정호일;이규령;이창노;임홍재
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2004.05a
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    • pp.925-930
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    • 2004
  • This paper is to study vibration effects of the dynamic vibration absorber. Multi-body dynamic analysis is carried out for the vehicle driveline model using ADAMS with flexible propeller shaft attached with the vibration damper. Primary bending mode frequency of the propeller shaft is obtained from the simulation and coincides with the experimental result. Various design parameters are studied in dynamic simulation operated by the engine torque input. This paper identifies the responses of dynamic vibration absorbers in the driveline with propeller shaft, which will be used to find out optimal design parameters.

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