• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2013.10a
• /
• pp.300-301
• /
• 2013

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2013.10a
• /
• pp.479-480
• /
• 2013

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2013.10a
• /
• pp.728-729
• /
• 2013

• Aerospace Engineering and Technology
• /
• v.9 no.2
• /
• pp.143-152
• /
• 2010

Development and verification of whole vibration test system was requested for developing a geostationary satellite. This satellite is enlarged significantly compared with fore-satellite in KARI. For vertical vibration test, new vertical vibration system was developed. For lateral vibration test, thermal equilibrium test was performed because of difference of thermal characteristics between test adapter and slip table. And lateral vibration system performance for overturning moment was verified by analysis and test. As the number of acquisition channels was increased, new shaker control and data acquisition system was installed. In this paper, verification process and techniques to improve test stability are introduced for the whole vibration test system.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 1991.04a
• /
• pp.47-52
• /
• 1991

주거환경을 침해하는 소음의 주된 요인은 가전제품으로서, 대부분의 가전제 품은 전기모터에 의해 구동된다. 가전제품을 작동시키는 전기모터는 가전제 품에 기진력을 주는 한편 공기중으로 소음을 방사함으로서 조용한 주거환경 을 해치게 된다. 따라서 조용하고 쾌적한 주거환경 확보를 위해서는 가전제 품용 구동모터의 소음을 효과적으로 차단 또는 감소해야 한다. 모터의 소음 원은 그 모터의 종류와 형태에 따라 약간씩은 다를 수 있으나 일반적으로 크게 기계적 소음, 공기 역학적 소음, 전자기 소음, 열/전기 화학적 소음 등 으로 분류된다. 이들 중 모터의 소음에 큰 영향을 주는 것은 기계적 소음, 공기 역학적 소음, 전자기 소음이며 열/전기 화학적 소음은 매우 작은 편이 다. 또한 공기 역학적 소음은 모터에 팬이 부착될 경우에만 큰 문제가 될 뿐 이며, 팬이 부착되지 않을 경우에는 기계적 소음과 전자기 소음이 주된 소음 원이 된다. 기계적 소음과 전자기 소음은 어느 것이 주된 소음원인지는 일반 적으로 잘 알 수 없기 때문에, 개별적인 연구와 실험을 통하여 파악해야 한 다. 기계적 소음은 주로 회전자의 불균형 회전에 의한 진동 및 그로 인한 외 부 프레임의 진동으로 대별되며, 전자기 소음은 주로 공급(Air-Gap)에서의 투과파(permeance wave)와 기자력(magneto-motive force)에 의한 반지름 방향의 힘에 의해 주로 발생된다. 본 연구에서는 기계적 소음과 전자기 소음 중 모터 소음에 영향이 큰 소음원을 판별해 내고 모델 실험을 통하여 감소 방안을 검토하였다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2003.05a
• /
• pp.1128-1133
• /
• 2003

A gas driven heat pump (GHP) core design comprises internal combustion engine, compressors incorporated to a cooling/heating system, rubber mountings and belt transmissions. Main excitation farces are generated by an engine, compressors themselves and belt fluctuation. It leads to high vibration level of the mount that can cause damage of GHP elements. Therefore an appropriate design of the mounting system is crucial in terms of reliability and vibration reduction. In this paper oscillation of the engine mount is explored both experimentally and analytically. Experimental analysis of natural frequencies and operational frequency response of the GHP engine mounting system enables to create simplified model for numerical and analytical investigations. It is worked out criteria f3r vibration abatement of the isolated structure. Influence of bracket stiffness between engine and compressors, suspension locations and damper performance is investigated. Ways to reduce excitation forces and improve dynamic performance of the engine-compressor mounting system are considered from these analyses. Implementation of the proposed approach permits to choose appropriate rubber mountings and their location as well as joining elements design A phase matching technique can be employed to control forces from main exciters. It enables to changing vibration response of the structure by control of natural modes contribution. Proposed changes lead to significant vibration reduction and can be easily utilized in engineering practice.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 1997.04a
• /
• pp.49-54
• /
• 1997

In this paper, vibration characteristics are considered about thermo-visco-plastic material under periodic thermal loading. When in high temperature region, thermo-visco-plastic structure has a periodic thermal loading, it is very important in an accumulated structure like a spacestation to investigate vibration characteristic, stress-strain characteristic is considered in various 2-D model by finite element method.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2001.11b
• /
• pp.1365-1369
• /
• 2001

ISO/TC 108은 진동, 기름 순도(purity), 열 변화 및 전류 변동과 같은 요소들을 이용한 기계상태의 전반적인 감시와 평가를 위한 지침을 제공하기 위한 의도로 일련의 규격을 개발하는 과정 중에 있다. (중략)

• The Science & Technology
• /
• v.32 no.6 s.361
• /
• pp.31-31
• /
• 1999

전자레인지가 발생하는 마이크로파의 파장은 물, 지방 및 당분의 고유진동수와 비슷한 파장을 지니고 있다. 열이란 분자의 운동에너지를 말하며 전자레인지의 전파와 사이에서 공명현상을 일으켜 음식의 온도가 올라가게 되는 것이다. 그러나 용기는 음식의 성분을 포함하고 있지 않기 때문에 열이 올라가지 않는다.

• Progress in Medical Physics
• /
• v.4 no.2
• /
• pp.49-58
• /
• 1993

The complex glow curves were split into isolated glow curves to be calculated the values of kinetic order, activation energy, escape frequency and density of initial trap from the independent glow curves using the mathematical method of thermally stimulated processes. The minimization of the intensity difference between measured and theoretical glow curve was done by the nonlinear least-square program. The results of the fitted curves were almost equal to the actual values of the parameters. Thermoluminescence from gamma ray irradiated ${\alpha}$-Al$_2$ $O_3$ over the range of 300K to 600K was split into six glow curves. The kinetic order, activation energy and escape frequency of first glow curve were obtained as 1, 1.12eV and 6.79X10$\^$12/sec$\^$-1/, respectively, which were similar to the results of other method. Also the parameters of the second and the third glow curve and so forth were calculated.