• Proceeding of EDISON Challenge
• /
• 2013.04a
• /
• pp.387-392
• /
• 2013

본 연구에서는 천음속 전투기 무장창 내부의 압력 진동을 제어하기 위해 F-111의 무장창을 2차원 공동(Cavity)으로 모델링하고, EDISON_전산열유체 시스템을 활용하여 공동의 형상 변화에 따라 발생하는 유동 특성을 분석하였다. 최근의 전투기들은 항력 감소와 스텔스 기능을 위해 무기를 기체 안에 내장하는데, 덮개를 열 때 발생하는 공동 형상에 의해 강한 압력 진동이 유발된다. 이러한 진동은 무장창과 주변 기계 장치에 구조적 진동을 일으키고 고장 또는 파괴를 유발하므로, 근본적인 해결책이 필요한 중요한 문제이다. 본 연구에서는 진동의 원인이 되는 전단층(Shear layer) 불안정성을 해결하기 위해 기존에 연구된 형상(Leading edge extension 및 Ramp)과 본 연구에서 새로 제안한 Ramp extension을 적용해 보았다. 그 결과 압력 진동의 원인이 되는 유동 특성이 줄어들고 압력 진동 역시 감소했음을 관찰할 수 있었다.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
• /
• 2011.11a
• /
• pp.72-73
• /
• 2011

• Tunnel and Underground Space
• /
• v.11 no.1
• /
• pp.14-19
• /
• 2001

The estimation of proper prediction method and the transformation method of environmental regulation standard were carried out by measuring blasting vibration. Vibration velocity was more adequate than vibration level in the blasting design by scaled distance. Thus, design and construction mutt be controlled by vibration velocity, and it is required that the vibration velocity is transformed to vibration level to meet regulation standard. Three transformation methods were studied. First, transformation formula is derived from the shock vibration data only. The second method it the transformation by correlation equation of vibration velocity and vibration level measured at the same time. The last one is the transformation of vibration velocity by FFT. It seems to be difficult to estimate damages by these methods because that every method shows considerable error. But transformation formula of PPV component to vibration level was most practical.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.4 no.2
• /
• pp.25-36
• /
• 2000

본 논문에서는 구조물이 과도한 기진력을 받을 때에 구조물의 진동 제어를 위하여 제안 되어진 여러 가지 포화 제어 알고리듬들의 유용성을 실제적인 관점에서 살펴보았다 제안된 포화 제어 알고리듬 중세서 수정된 뱅뱅 제어 알고리듬이 매우 유용한 것임을 확인할 수 있었으나 이는 제어력 파형 결정 파라미터의 어떤 범위내에서만 효과적이며 그 범위를 넘어서는 경우에 있어서는 제어기를 불안정하게 할 수 있음을 확인할 수 있었다 따라서 수정된 뱅뱅 제어 알고리듬의 적용시에 과도한 외부 기진력에 대하여 제어기의 안정적인 작동에 의한 구조물의 진동제어효과를 얻기 위해서 제어력 파형 파라미터를 과도 기진력의 크기에 따라 변화시키는 적응형의 방법을 제안하였고 이의 유용성을 수치실험 및 유압식 질량 감쇠기를 장착한 축소 구조물 검증 실험을 통하여 확인하였다.

• Journal of KSNVE
• /
• v.11 no.2
• /
• pp.180-186
• /
• 2001

자동차의 소음 진동은 파워트레인(엔진과 변속기)과 자동차의 차체 및 이 두 부분 연결하는 프레임의 동력학적인 적절한 조화에 의해서 좌우된다. 따라서 CAE를 이용한 파워트레인 및 차체의 최적 설계가 자동차 개발의 초기 개념 설계단계에는 중요한 역할을 하지만, 이 후 많은 자동차의 부품들이 서로 결합되어 완성되어지는 시작차 단계에서는 초기에 예상하지 못한 문제점들이 발생한다.(중략)

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2011.04a
• /
• pp.439-440
• /
• 2011

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.24 no.9
• /
• pp.667-674
• /
• 2014

A ship's propulsion shafting system is subjected to varying magnitudes of intermittent loadings that pose great risks such as failure. Consequently, the dynamic characteristic of a propulsion shafting system must be designed to withstand the resonance that occurs during operation. This resonance results from hydrodynamic interaction between the propeller and fluid. For ice-class vessels, this interaction takes place between the propeller and ice. Producing load- and resonance-induced stresses, the propeller-ice interaction is the primary source of excitation, making it a major focus in the design requirements of propulsion shafting systems. This paper examines the transient torsional vibration response of the propulsion shafting system of an ice-class research vessel. The propulsion train is composed of an electric motor, flexible coupling, spherical gears, and a propeller configuration. In this paper, the theoretical analysis of transient torsional vibration and propeller-ice interaction loading is first discussed, followed by an explanation of the actual transient torsional vibration measurements. Measurement data for the analysis were compared with an applied estimation factor for the propulsion shafting design torque limit, and they were evaluated using an existing international standard. Addressing the transient torsional vibration of a propulsion shafting system with an electric motor, this paper also illustrates the influence of flexible coupling stiffness design on resulting resonance. Lastly, the paper concludes with a proposal to further study the existence of negative torque on a gear train and its overall effect on propulsion shafting systems.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.14 no.3
• /
• pp.607-618
• /
• 1994

Effects of wave grouping on the harbor oscillation are studied in order to clarify the energy source of harbor resonance. The resonant periods of Donghae harbor and Imwon harbor are calculated using the boundary integral equation method. Also, the periods of the group-bounded long waves due to the irregular wave group are calculated using the theory developed in this study. Analyzing from the view point of period, it is concluded that the group-bounded long waves due to the irregular wave group can cause resonance in small harbors such as fishery harbors, and heavy ship motion in large harbors such as industrial ones.

• Tunnel and Underground Space
• /
• v.10 no.3
• /
• pp.486-491
• /
• 2000

Blasting vibrations velocity had been used to design blasting pattern and predict damage-possibility of structures. As vibration levels are currently required to estimate the damage concerning human-body and livestock, so measured vibration velocities must be transformed into vibration levels. In this study, the digital filter program was developed to transform measured data into vibration levels. Simple harmonic vibrations and measured data obtain by Blastmate series (Instantel Inc.) were applied to the digital filter program. As a result, simple harmonic vibrations and measured data were successfully transformed into vibration levels using the developed program. Measured data from any instrument with ASCII output-function will similarly be transformed into level units.

• Tunnel and Underground Space
• /
• v.23 no.6
• /
• pp.521-537
• /
• 2013

While microseismicity induced by hydraulic stimulation carried out for EGS is useful means in estimating the range of permeability increase, it also affect surface structures and environments. In order to establish a mitigation plan for microseismicity triggered by hydraulic stimulation, we reviewed world-wide guidelines on the impact of ground vibration on the surface structure and human environment by blasting. Case studies from Europe and USA on the microseismicity by hydraulic stimulation are presented and suggestions are made for the guidelines on ground vibration by hydraulic stimulation for the ongoing Pohang EGS project.