• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.837-843
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• 2006

As environmental vibration requirements on precision equipment become more stringent, use of pneumatic isolators has become more popular and their performance is subsequently required to be further improved. Performance of passive pneumatic isolators is related to various design parameters in a complicated manner and, hence, is very limited especially in low frequency range by chamber volume. In this study, transmissibility behavior of the pneumatic isolators depending on frequency and dynamic amplitude are presented. Then, an active control technique, time delay control, which is adequate for a low frequency nonlinear system, is applied. A procedure of applying the time delay control law to a pneumatic isolator is presented and it's effectiveness in the transmissibility performance is shown. Comparison between passive and active pneumatic isolators is made based on simulation.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.936-939
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• 2006

The pneumatic isolator is widely adopted for anti-vibration of precision measuring and manufacturing equipments. But, when the precision demand on anti-vibration is extreme or the load is moving, the performance of anti-vibration can not meet satisfaction. In these cases, as a complementary, active vibration suppression system can be added for advanced performance. In this paper, an active control system is presented, which uses electromagnetic actuators for vibration suppression. The anti-vibration characteristic of pneumatic isolator is analyzed for system modeling and actuator specifying. The modeling and the 3D dynamic simulation is performed for control system design. For the electromagnetic actuator design, the magnetic flex density and the current-force characteristic analysis are achieved.

• International Journal of Railway
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• v.5 no.4
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• pp.163-166
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• 2012

Many different types of floating slab track have been developed and installed around the world to reduce vibrations and noise originating in the surrounding environment. The main objective of this study is to examine the influence of slab length on behavior of floating slab track based on rail-slab-isolator interaction. The floating slab track is modeled by the connection between rail, slab, isolator, and slab mat in the transition zone. All elements were assembled in a simplified two-dimensional (2D) finite element model (FEM). The maximum length of FST is then investigated based on the maximum additional rail stress criterion as described in UIC 774-3R since no fully accepted design criteria for the slab length in FST systems currently exist.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.341-345
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• 2017

In this study, the Inlet/Isolator model experiments performed at Texas University were performed by 2-dimensional RANS computerized analysis. First, supersonic flow conditions were analyzed and compared with experimental surface pressure results, and the flow structure was analyzed by confirming Mach number distribution and numerical shadowgraph. Then, the inlet unstart condition was given by changing the back pressure, and the URANS analysis was performed to confirm the progress of inlet unstart.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.05a
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• pp.231-231
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• 2005

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.10a
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• pp.179-183
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• 2001

Vibration isolation of mechanical systems, in general is achieved through either passive or active vibration control system. Although passive vibration isolators offer simple and reliable means to protect mechanical system from vibration environment, passive vibration isolator has inherent performance limitation. Whereas, active vibration isolator provide significantly superior vibration-isolation performance. Recently, many studied and applications are carried out in this field. In this study, vibration-isolation characteristics of active vibration control system using electromagnetic force actuator are investigated. Some control algorithms. Optimal Feedforward are used for active vibration isolation. Form the experimental results of each control algorithms, active vibration isolation characteristics are investigated.

• Proceedings of the Korean Society of Veterinary Clinics Conference
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• 2008.05a
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• pp.127-127
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• 2008

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 1998.04a
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• pp.147-154
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• 1998

The purpose of this paper is to propose the draft guidelines of seismic isolation design of Liquid Metal Reactor (LMR) using high damping laminated rubber bearings. The scopes of guidelines include design requirements of a seismically isolated system and components, seismic isolator, isolation system, interface system between seismic isolation and non-seismic isolation part, qualification and acceptance tests of seismic isolator, seismic isolation reliability, and seismic safety and monitoring system. Proposed guidelines shall be revised to extend to general design guideline for nuclear facilities by further research and discussions.

• Proceedings of the Optical Society of Korea Conference
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• 2003.07a
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• pp.112-113
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• 2003

광통신 시스템에는 다양한 광소자들이 삽입되어 사용된다. 특히 보다 많은 정보의 전송을 위하여 WBM 소자들이 흔히 사용되고 있다. 이와 같이 data 처리용량 및 속도 증가에 대응하기 위한 광섬유의 개발이 활발하게 연구되고 있으며 data 전송용량이 증가되면 channel 파장 대역폭이 좁아지게 되고 전송 속도가 증가되면 색분산 등 광섬유의 비선형성에 의한 영향이 크게 나타나게 된다. 또한 장거리 통신망 등에서는 온도 변화에 의해 분산 기울기 변화가 전송 제한 요인이 된다. (중략)

• Proceedings of the Optical Society of Korea Conference
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• 1989.02a
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• pp.7-11
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• 1989

A Faraday rotator is designed with the HOYA FR-5 rotator glass. We find that traveling light rotates 45$^{\circ}$in the glass when magnetic field intensity is about 3.0$\times$105AT/m. The current of 2.7KA flowing in the coil of the 0cm diameter, 29cm long and 41 windings generates this magnetic field. A pulse forming network is designed for this current of 84 sec duration. The network is analyzed numerically to find the relevant circuit parameters for the flattest current waveform.