• Smart Structures and Systems
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• v.19 no.5
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• pp.487-497
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• 2017

Semi-active devices use the building's own motion to produce resistive forces and are thus strictly dissipative and require little power. Devices that independently control the binary open/closed valve state can enable novel device hysteresis loops that were not previously possible. However, some device hysteresis loops cannot be obtained without active analog valve control allowing slower, controlled release of stored energy, and is presents an ongoing limitation in obtaining the full range of possibilities offered by these devices. This in silico study develops a proportional-derivative feedback control law using a validated nonlinear device model to track an ideal diamond-shaped force-displacement response profile using active analog valve control. It is validated by comparison to the ideal shape for both sinusoidal and random seismic input motions. Structural application specific spectral analysis compares the performance for the non-linear, actively controlled case to those obtained with an ideal, linear model to validate that the potential performance will be retained when considering realistic nonlinear behaviour and the designed valve control approach. Results show tracking of the device force-displacement loop to within 3-5% of the desired ideal curve. Valve delay, rather than control law design, is the primary limiting factor, and analysis indicates a ratio of valve delay to structural period must be 1/10 or smaller to ensure adequate tracking, relating valve performance to structural period and overall device performance under control. Overall, the results show that active analog feedback control of energy release in these devices can significantly increase the range of resetable, valve-controlled semi-active device performance and hysteresis loops, in turn increasing their performance envelop and application space.

• Journal of the Korean Society for Precision Engineering
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• v.29 no.12
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• pp.1331-1339
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• 2012

Safety valve used in LNG/LNG-FPSO ships is a high value valve, and it plays an important role in maintaining a fixed level of pressure by emitting LNG gas out of pipes in LNG piping system under the cryogenic and high-pressure condition when the pressure of the system connected with the LNG storage tank and pipes reaches over the set pressure. The structural stability is required for the inner pressure and thermal load because of the cryogenic and high-pressure condition, and a reliability of the safety valve is necessary for impact and deformation by opening the valve. But, the safety valve, which plays a key role for a safety of the transport and storage system, is depended on imports for over 90%, and in domestic production, the design of the valve is performed on the basis of experiences of the works without quantitative analysis for the inner operation characteristics and structural stability of the valve. In this study, impact velocity is calculated by theoretical analysis for obtaining the structural stability of the guide according to the impact load by opening the valve. The shape of the guide and the diaphragm for satisfying the structural stability are suggested and verified by using a thermal-structural analysis.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.05a
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• pp.1051-1054
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• 2000

We developed the micro CSF (celebrospinal fluid) shunt valve with surface and bulk micromachining technology in polymer MEMS. This micro CSF shunt valve was formed with four micro check valves to have a membrane connected to the anchor with the four bridges. The up-down movement of the membrane made the CSF on & off and the valve characteristic such as open pressure was controlled by the thickness and shape of the bridge and the membrane. The membrane, anchor and bridge layer were made of the $O_2$ RIE (reactive ion etching) patterned Parylene thin film to be about 5~10 microns in thickness on the silicon wafer. The dimension of the rectangular nozzle is 0.2＊0.2 $\textrm{mm}^2$ and the membrane 0.45 mm in diameter. The bridge width is designed variously from 0.04 mm to 0.12 mm to control the valve characteristics. To protect the membrane and bridge in the CSF flow, we developed the packaging system for the CSF micro shunt valve with the deep RIE of the silicon wafer. Using this package, we can control the gap size between the membrane and the nozzle, and protect the bridge not to be broken in the flow. The total dimension of the assembled system is 2.5＊2.5 $\textrm{mm}^2$ in square, 0.8 mm in height. We could precisely control the burst pressure and low rate of the valve varing the design parameters, and develop the whole CSF shunt system using this polymer MEMS fabricated CSF shunt valve.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.10
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• pp.2773-2778
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• 1994

Tumbling motion is very effective for turbulence enhancement during compression process in the cylinder of 4-valve engines. In this paper the tumble decay mechanism for different intake port configuration were measured using laser Doppler velocimetry. Analysis of the tumble decay mechanism was achieved by means of two non-dimensional parameters, defined as tumble eccentricity and shape factor in tumble velocity profile, in addition to the tumble moment.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.314-315
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• 2007

자동차용 부품인 밸브씰 비전 검사 시스템을 개발하였다. 구성부품은 8 대의 독립형 CCD 카메라, 검사를 위해 밸브씰을 공급해 주는 기구장치 및 검사 모니터링 시스템으로 구성되었다. 밸브씰의 대표적인 불량 유형 1가지에 대한 영상처리 알고리즘을 제안하고, 알고리즘의 효율성은 실험을 통하여 확인하였다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2011.06a
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• pp.1375-1376
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• 2011

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.6
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• pp.584-589
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• 2009

As the automobile energy efficiency stands out an important matter of interest, the magnetic engine valve system receives attention. It has an advantage of no engine power leakage in opening and closing the valve. Moreover, it generates much bigger force than the piezo actuator system, so it can be a good alternative system of the cam and camshaft system. However, since the valve system is not light enough, it is necessary to make its weight reduce. In this study, topology optimization is applied to find the optimal shape of the armature in a magnetic valve system combined with the finite element analysis for the magnetic field analysis. The result is used to obtain a concept design. The adjoint variable method is employed in order to calculate the design sensitivity of the magnetic driving force in the armature component mostly to reduce the computational time during the repeated sensitivity calculation. The sequential linear programming is employed for the optimization algorithm.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2004.11a
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• pp.237-240
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• 2004

Sulfur Hexafluoride, SF6 is widely used for leak detection and as a gaseous dielectric in transformers, condensers and circuit breakers. SF6 gas is also effective as a cleanser in the semiconductor industry. This paper presents a numerical study of the sealing force of disk type seal in SF6 gas safety valve. The sealing force on the disk seal is analyzed by the FEM method based on the Taguch's experimental design technique. Disk seals in SF6 gas safety valve are designed with 9 design models based on 3 different contact length, compressive ratio and gas pressure. The calculated results of Cauchy stress and strain showed that the sealing characteristics of Teflon PTFE is more effective compared to that of FKM(Viton), which is related to the stiffness of the materials. And also, the contact length of the disk seal is important design parameter for sealing the SF6 gas leakage in the safety valve.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.850-853
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• 2011

The position indicator for cryogenic valves used in space launch vehicle should have high reliability and accuracy. Because the valves operate in cryogenic environment, the position indicator has to measure the valve status independently of the environmental factor, such as moisture and external contamination. We have developed the position indicator using a permanent magnet and reed switches to satisfy these requirements. We analyzed the characteristics of a permanent magnet and reed switches, then selected the appropriate components for cryogenic temperature. The shape and position of components were also considered to measure the open/close information of valve accurately Finally, the position indicator was applied to the valve prototype model, and verified the feasibility of design parameters.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.6
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• pp.3821-3826
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• 2014

This paper proposes a methodology for developing the performance of a solenoid valve for vehicles based on the dynamic analysis model by an electromagnetic field. The high performance solenoid model with a low current and high thrust was induced through the shape optimal design of the yoke and plunger. To perform the dynamic analysis of the solenoid valve, the input current profile was analyzed. The speed and thrust information was analyzed by FEM with this current profile. The co-simulation method of the circuit model of control logic and electromagnetic model of the solenoid valve was also proposed to analyze the performance with several current patterns. Finally, the performance of the original model and optimal one was compared.