• 한국화재소방학회논문지
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• 제11권1호
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• pp.47-54
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• 1997

소방자동차를 비롯한 모든 자동차의 비툴립 강성이 약하면 차체에 크혜이 발생함과 동시에 고유진 동수가 낮아져 진동소음 발생의 원인이 된다. 이 논문은 최소한의 중량증가로 비틀림 강성을 최대한 중 가시키는 방안올 제시한 것에 관한 것으로, 방안 검토를 위하여 탄성론을 이용한 이론해석을 실시하였 고, 또한 이의 검증을 위하여 유한요소법에 의한 해석 및 실제 차체를 이용한 실험을 질시하였다. 본 논 문에서 사용한 자동차는 숭용차를 사용하였다. 그 이유는 실험 및 계산이 용이하고, 또한 계산결과를 소방자동차 퉁을 비롯한 모든 자동차에 적용 할 수 있기 때문이다.

• Structural Monitoring and Maintenance
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• 제4권4호
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• pp.351-364
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• 2017

In this study effects of various parameters like a number of bays, the stiffness of the structure along with the height of the structure was examined. The fundamental period of vibration T of the building is an important parameter for evaluation of seismic base shear. Empirical equations which are given in the Indian seismic code for the calculation of the fundamental period of a framed structure, primarily as a function of height, and do not consider the effect of number of bays and stiffness of the structure. Building periods predicted by these expressions are widely used in practice, although it has been observed that there is scope for further improvement in these equations since the height alone is inadequate to explain the period variability. The aim of this study is to find the effects of a number of bays in both the directions, the stiffness of the structure and propose a new period equation which incorporates a number of bays, plan area, stiffness along with the height of the structure.

• 펄프종이기술
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• 제43권4호
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• pp.49-58
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• 2011

The maximum drying shrinkage velocity was proposed to verify bulk and stiffness improvement mechanism during drying according to papermaking parameters. It was based on the wet-web shrinkage behavior without the restraint of wet-web during drying, so intact drying impact could be measured. Bulking agent reduced the drying shrinkage and the maximum drying shrinkage velocity, so paper bulk increased and paper strength decreased. When adding cationic starch to stock with the bulking agent for strengthening, the bulk was increased further with additional decreasing of the drying shrinkage and the maximum drying shrinkage velocity. Paper strength also increased except tensile stiffness index with decreasing the drying shrinkage and the maximum drying shrinkage velocity. When using additional strength additives for strengthening of fiber interfaces extended by bulking agent and cationic starch, amphoteric strength additive increased paper stiffness without loss of paper bulk. It was considered that the added amphoteric strength additives were cross-linked to the stretched cationic starch and this cross-linking increased elasticity of fiber-polymer-fiber interfaces without changing the drying behavior. Paper bulk could be increased with decreasing the maximum drying shrinkage velocity. The drying shrinkage of paper also could be controlled by fiber-to-fiber bonding interfaces by the bulking agent. In this case, paper strength including stiffness was decreased by reducing fiber-to-fiber bonding but it could be improved by strengthening fiber-to-fiber interfaces with polymer complex without loss of bulk.

• 한국지반공학회논문집
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• 제40권3호
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• pp.55-63
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• 2024

잔탄검 바이오폴리머는 대표적인 친환경 지반안정제로서, 넓은 범위의 온도와 pH에서 높은 안정성을 보이는 장점이 있다. 사질토 지반에 대한 잔탄검 바이오폴리머 적용 시 흙 입자 결합력 증대효과는 잔탄검 매트릭스의 건조과정에 의존하므로, 잔탄검 바이오폴리머 수용액의 건조과정에 따른 사질토 전단강성 증대효과에 대한 연구가 요구된다. 본 연구에서는 잔탄검 바이오폴리머 주입에 의한 사질토의 전단강성 개선효과를 평가하고자, 농도가 다른 잔탄검 바이오폴리머 수용액을 주입한 주문진 표준사에 대하여 건조 경과에 따른 전단파속도를 측정하였으며, 건조도의 정량적 평가를 위하여 전기비저항 측정이 병행되었다. 건조시간 경과에 따라 전단파속도 및 전기비저항 모두 증가하는 양상을 보였으며, 이를 통하여 건조과정에 따른 바이오폴리머 혼합토의 전단강성 증대효과를 확인하였다. 또한, 바이오폴리머 농도에 따른 전단파속도 측정 결과, 초기 농도가 높을수록 건조과정에 따라 높은 전단강성 증대효과를 나타내었다. 본 연구의 결과는 바이오폴리머 수용액 주입에 의한 사질토 지반의 전단강성 개량효과 예측에 활용될 수 있을 것으로 기대된다.

• 한국소음진동공학회논문집
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• 제18권1호
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• pp.110-122
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• 2008

Pneumatic vibration isolator typically consisting of dual-chamber pneumatic springs and a rigid table are widely employed for proper operation of precision instruments such as optical devices or nano-scale equipments owing to their low stiffness- and high damping-characteristics. As environmental vibration regulations for precision instruments become more stringent, it is required to improve further the isolation performance. In order to facilitate their design optimization or active control, a more accurate mathematical model or complex stiffness is needed. Experimental results we obtained rigorously for a dual-chamber pneumatic spring exhibit significantly amplitude dependent behavior, which cannot be described by linear models in earlier researches. In this paper, an improvement for the complex stiffness model is presented by taking two major considerations. One is to consider the amplitude dependent complex stiffness of diaphragm necessarily employed for prevention of air leakage. The other is to employ a nonlinear model for the air flow in capillary tube connecting the two pneumatic chambers. The proposed amplitude-dependent complex stiffness model which reflects dependency on both frequency and excitation amplitude is shown to be very valid by comparison with the experimental measurements. Such an accurate nonlinear model for the dual-chamber pneumatic springs would contribute to more effective design or control of vibration isolation systems.

• 한국지반공학회논문집
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• 제31권4호
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• pp.31-43
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• 2015

성토지지말뚝구조의 다양한 조건에서 토목섬유의 인장강성 변화가 성토체 및 토목섬유의 연직변위와 말뚝효율에 미치는 영향을 수치해석적으로 평가하였다. 매개변수 해석을 위해 연약지반의 강성, 성토재의 내부 마찰각과 팽창각, 토목섬유를 포함한 복합 재료층의 휨 강성을 변화시켰다. 토목섬유의 인장강성이 증가하면 말뚝효율이 증가하지만 그 증가량은 해석 조건에 따라 다르다. 성토재의 내부 마찰각이 매우 낮거나 복합 재료층의 휨 강성이 매우 높으면 뚜렷한 말뚝효율 증가가 나타났다. 연약지반의 강성이 매우 낮은 경우에 토목섬유의 인장강성을 증가시키면 뚜렷하게 연직 변위가 감소하였다. 복합 재료층의 휨 강성이 높으면 토목섬유 인장강성을 증가시켜 말뚝효율이 크게 향상되었다.

• 제어로봇시스템학회논문지
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• 제14권4호
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• pp.406-410
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• 2008

This paper presents a new robot calibration algorithm with joint stiffness parameters for the enhanced positioning accuracy of industrial robot manipulators. This work is towards on-going development of an industrial robot calibration software which is able to identify both the kinematic and non-kinematic robot parameters. In this paper, the conventional kinematic calibration and its important considerations are briefly described first. Then, a new robot calibration algorithm which simultaneously identifies both the kinematic and joint stiffness parameters is presented and explained through a computer simulation with a 2 DOF manipulator. Finally, the developed algorithm is implemented to Hyundai HX165 robot and its resulting improvement of the positioning accuracy is addressed.

• 한국도로학회논문집
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• 제8권2호
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• pp.31-35
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• 2006

Cement stabilisation is a common method for stabilising recycled road base material and provides a longer pavement life. With cement effect, the increment of stiffness in the stabilised layer would provide better load transfer to the pavement foundation. The recycling method provides an environmentally option as the existing road base materials will not be removed. This paper presents a case study of a trial section along the North-South Expressway in West Malaysia, where the Falling Weight Deflectometer (FWD) was implemented to evaluate the compressive strength and in-situ stiffness of the cement stabilised road base material. The improvement in stiffness of the cement stabilised base layer was monitored, and samples were tested during the trial. FWD was found to be useful for the structural assessment of the cement-stabilised base layer prior to placement of asphalt layers. Results from the FWD were applied to verify the assumed design parameters for the pavement. Using the FWD, an empirical correlation between the deflection and the stiffness modulus of the pavement foundation is proposed.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1999년도 가을 학술발표회 논문집
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• pp.69-78
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• 1999

The stiffness of slab concrete section is not considered as effective in the existing method of construction for continued steel box girder bridge. Using lifting system and filled concrete, it is possible to make stiffness of slab concrete section effective and improve stiffness of negative moment section. It was proved that the stress of upper flange in positive moment is significantly lower than case of existing method through the stress comparison. This stress difference made possible to rearrange flange thickness and as the result of this rearrangement, the amount of steel and height of girder can be reduced up to 13.23% and 11.5%.

• 한국군사과학기술학회지
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• 제10권3호
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• pp.181-188
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• 2007

This paper presents a torque control method of a hydraulic actuation system for measuring the dynamic stiffness of missile fin actuators. We propose a new control technique called Dual Dynamic Torque Feedback Control(DDTFC), which improves the stability of the torque control system and enables fast tracking of torque command. The developed control scheme is derived from the physical understanding based on mathematical modelling and analysis. The dynamics of hydraulic torque control servo-system is unravelled via physics-based modelling and nonparametric system identification. In order to verify the effectiveness of the method, the experiment is carried out with a test equipment for measuring the dynamic stiffness. The experiment and simulation results show that DDTFC gives stability improvement.