• 소음진동
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• 제11권2호
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• pp.292-300
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• 2001

This research is concerned with the validation of the modeling technique and controller design for slewing beam structures. When cantilever beam rotates about axes perpendicular to the undeformed beam's longitudinal axis, it experiences inertial loading. Hence, the beam vibrates from the initial stage of slewing. In this paper, the analytical model for a single slewing flexible beam with surface bonded piezoelectric sensor and actuator is developed using the Hamilton's principle with discretization by the assumed mode method. Comparisons with the theoretical model are made based upon the frequency responses and time responses. A new factor called the coupling coefficient is introduced to incorporate the discrepancies between the theoretical and experimental results. The slewing is achieved by applying the PID control, which is found to be less sensitive to vibrations. The vibrations are controlled by PPF controller, which is found to be effective in suppressing residual vibrations after slewing. The vibrations occurred during slewing is difficult to control because the piezoceramic actuator is not powerful enough to overcome inertial loadings.

• International Journal of Aeronautical and Space Sciences
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• 제3권2호
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• pp.13-23
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• 2002

In this paper, we present a sliding mode control strategy for the re-orientation maneuver of rigid spacecraft containing rotating wheels. The wheels are considered as internal devices, and external inputs are employed for generation of control commands. The formulation is developed for a general case while particular example is applied to pitch bias momentum spacecraft with a single momentum wheel. The resultant control commands are used to take the gyroscopic effects into account which are caused by the rotating wheels. The controller designed demonstrates that the nutational motion of the pitch bias momentum spacecraft is effectively controlled. It is also assumed that the external control torque device is of on-off nature, and pulse width modulation technique is applied to construct proper control torque history.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2004년도 전력전자학술대회 논문집(1)
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• pp.163-166
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• 2004

The conventional fluorescent lamp dimming system using an another control line is complex and will increased the cost. Therefore, many studies have focused on the wireless communication, but it is not fit for dimming system because of the interference generated by the infra-red light of lamp or switching noises in ballast. So, we applied the power line communication on the dimming system and we proposed a new coupling circuit using the voltage controlled impedance convertor for improving the performance of the FH/SS PLC modem. The performance for the proposed modem is evaluted by the BER.

• Bulletin of the Korean Chemical Society
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• 제28권12호
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• pp.2409-2413
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• 2007

Time resolved phosphorescence of Dibromobenzophenone (DBBP) choleic acid crystal was observed at 4.2 K as functions of excitation energy and delay time. The experimental results reveal that the energy transfer efficiency is dependent on the excitation energy, i.e. the density of acceptors sites. As the excitation energy or delay time increases, the resonance phosphorescence does not broaden and shift gradually, rather a broad luminescence band develops about 290 cm?1 to lower energy of the resonance phosphorescence. The observation implies that energy transfer from high to low energy sites in this system is controlled by emission of phonons or vibrons. The data of time resolved experiments were analyzed in terms of a mechanism involving direct donor-acceptor excitation transport by exchange coupling. It was concluded that an isotropic twodimensional exchange interaction topology is consistent with energy transfer in this system.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2008년도 International Meeting on Information Display
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• pp.1305-1308
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• 2008

In this study, we redesigned the reliable integrated on-panel display gate driver that was equipped with dual pull-down as well as controlled discharge-path structure to reduce the high voltage stress effect and realized with TSMC 0.35 um CMOS-based technology before. An improved discharge path and a low noise design are proposed for our new a-Si TFT process implementation. Our novel reliable gate driver design can make each cell of shift register to be insensitive to the coupling noise of that stage.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2000년도 춘계종합학술대회
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• pp.128-131
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• 2000

This paper describes design for dual-linear polarization antenna using EMC(electromagnetic-coupled) dipole. EMC dipole has a simple element structure and it is fed by microstrip line. Vortical and horizontal polarization are determined by structure of dipole fed by microstrip line. FDTD Method is used for an analysis of antenna element. Length, width, height and offset of dipole are designed for 1-element antenna. Resonant length of diploe differs from the calculated value by a formula because of coupling effect of dipole and feed line. Radiation Power is controlled by the offset of dipole. In prectical fabrication of antenna array, a constant height of dipoles is required. Therefore, the teflon plate with height of 0.8 mm is considered in antenna element design for the vertical polarization.

• Journal of Electrochemical Science and Technology
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• 제4권4호
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• pp.146-152
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• 2013

We demonstrate that carbon electrodes screen-printed directly on cellulose paper can be employed to perform bipolar electrochemistry. In addition, an array of 18 screen-printed bipolar electrodes (BPEs) can be simultaneously controlled using a single pair of driving electrodes. The electrochemical state of the BPEs is read-out using electrogenerated chemiluminescence. These results are important because they demonstrate the feasibility of coupling bipolar electrochemistry to microfluidic paperbased analytical devices (${\mu}PADs$) to perform highly multiplexed, low-cost measurements.

• 전자공학회논문지D
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• 제34D권4호
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• pp.79-86
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• 1997

An electro-optic polymer digital optical switch with rib waveguides is designed and fabricated by using the RIE method. POlarization-independent and wavelength-insensitive operation is demonstrated at the wavelengths of 1.3mm and 1.55mm, for the first time in electro-optic polymer-based devices. The rib waveguides have been designed to achieve good guiding properites for both TE and TM polarizations by controlling the etching depth as well as its aspect ratio. Especially theetching depth is controlled to change the guided mode profiles of the rib waveguide and thus to achieve an optimum coupling in the branch. The measured crosstalk is better than -16dB and the extincton ratio of each output port is greater than 16dB.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2003년도 추계학술발표회
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• pp.454-457
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• 2003

A new approach for groundwater treatment combines a permeable Fe(0) barrier to breakdown higher chlorinated solvents like PCE and TCE with a downgradient aerobic biological treatment system to biotransform less chlorinated solvents, such as DCE and vinyl chloride (VC). The expected bacterial performance downgradient of an Fe(0) barrier was evaluated through laboratory batch experiments with a toluene-degrading mixed culture that cometabolically transforms cis-1,2-DCE and VC. The amount of cis-1,2-DCE (initially at 2,000 ppb) and VC (initially at 2,000 ppb) transformed was controlled by the initial toluene (20,000 ppb) concentration. VC was removed much more effectively than Cis-1,2-DCE, and a higher toluene concentration in comparison to the co-substrate concentrations was needed for complete co-substrate removal. Overall, the coupling of an Fe(0) barrier and subsequent biodegradation appears feasible for remediation of complex mixtures of chlorinated solvents and petroleum hydrocarbons in groundwater

• 한국세라믹학회지
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• 제34권10호
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• pp.1037-1044
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• 1997

Mechanical properties and water stability of HAC/PVA based MDF cement composite were investigated using polyurethane(PU) resin, silane coupling agent and various PVA. The results were as follows ; The flexural strength of MDF cement composite increased as increasing with PVA content. Low-viscosity PVA developed higher flexural strength than high-viscosity PVA under a drying curing condition. But the strength of water immersed specimen decreased. Water stability of MDF cement improved as increasing with content of PU. Consequently, water stability of polyurethane 7% added MDF cement was about 2 times higher than that of the controlled specimen. Furthermore, the strength and water stability of diamine group based silane couling agent in using MDF cement increased and improved dramatically.