• 제어로봇시스템학회논문지
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• 제18권7호
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• pp.617-621
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• 2012

This paper studies asymptotic consensus problem for linear multi-agent systems. We propose a distributed state feedback control algorithm for solving the problem under fixed and undirected network communication. In contrast with the conventional algorithms that use global information (e.g., graph connectivity), the proposed algorithm only uses local information from neighbors. The principle for achieving asymptotic consensus is that, for each agent, a distributed update law gradually increases the coupling gain of LQR-type feedback and thus, the overall stability of the multi-agent system is recovered by the gain margin of LQR.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1999년도 학회창립 10주년 기념 1999년도 가을 학술발표회 논문집
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• pp.561-564
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• 1999

The uniform state of prestress in a fully prestressed concrete members shows reductions of more than half of the initial prestress in the construction and coupling joint vicinity. Especially, at a zone x/d=0.2 above the construction joint where at the edge of the member, a quite localized reduced stress state of 1/3 of uniform stress is encountered. Five full-scale test specimens were segmentally constructed and post-tensioned and analytic models is used to verify and validate measured test results. The encountered highly nonuniform stress/strain state in the coupling joint vicinity requires special design consideration for the successful application of tendon couplers.

• Journal of electromagnetic engineering and science
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• 제10권3호
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• pp.175-178
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• 2010

In this paper, a millimeter-wave multi-beam antenna is studied by rotating the antipodal linear tapered slot antenna(ALTSA) with respect to a center is successfully designed. In order to lowering the SLL and enhancing the isolation between the ALTSA elements, a row of metallic via is inserted between the ALTSAs. A 9 beams antenna is designed and experimented at Ka band. The measured and simulated results agree well with each other. The antenna can provide horizontal wide angle coverage up to ${\pm}62^{\circ}$. The gain of each beam can achieve about 12.5 dB. The mutual coupling between ports is all below 20 dB.

• Wind and Structures
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• 제10권5호
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• pp.421-435
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• 2007

A two-dimensional flutter analysis method (2d-3DOF method) was developed to simultaneously investigate the relationship between oscillation parameters and aerodynamic derivatives of three degrees of freedom, and to clarify the coupling effects of different degrees of freedom in flutter instability. With this method, the flutter mechanism of two typical bridge deck sections, box girder section and two-isolated-girder section, were numerically investigated, and both differences and common ground in these two typical flutter phenomena are summarized. Then the flutter stabilization effect and its mechanism for long-span bridges with box girders by using central-slotting were studied by experimental investigation of aerodynamic stability and theoretical analysis of stabilizing mechanism. Possible explanation of new findings in the evaluation trend of critical wind speed through central vent width is finally presented.

• Bulletin of the Korean Chemical Society
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• 제10권3호
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• pp.298-302
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• 1989

The strengths of two-photon transitions from the ground state to excited vibronic states in benzene are calculated by using the CNDO/2-U wave functions. The role of vibronic coupling in two-photon absorption process is discussed. The $A_{1{\bar{g}}}-A_{2g}^+$ two-photon transitions, which are forbidden by the identity-forbidden selection rule in single frequency two-photon absorption, are too weak to be experimentally observed even when two photons of different energies are used. It is because the transitions are forbidden also by the pseudo-parity selection rule which are applicable for alternant hydrocarbons such as benzene. It is also shown that the vibronic coupling is not very effective in altering the pseudo-parity property of the electronic state. The strength of the vibronically induced two-photon absorption is strongly affected by the presence of an electronic state from which two-photon absorption can borrow the intensity. It is pointed out that the pseudo-parity selection rule may be violated in such cases.

• JSTS:Journal of Semiconductor Technology and Science
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• 제8권2호
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• pp.128-133
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• 2008

Phase-change random access memory (PRAM) chip cell phase of amorphous state is rapidly changed to crystal state above 160 Celsius degree within several seconds during Infrared (IR) reflow. Thus, on-board programming method is considered for PRAM chip programming. We demonstrated the functional 512Mb PRAM with 90nm technology using several novel core circuits, such as metal-2 line based global row decoding scheme, PN-diode cells based BL discharge (BLDIS) scheme, and PMOS switch based column decoding scheme. The reverse-state standby current of each PRAM cell is near 10 pA range. The total leak current of 512Mb PRAM chip in standby mode on discharging state can be more than 5 mA. Thus in the proposed BLDIS control, all bitlines (BLs) are in floating state in standby mode, then in active mode, the activated BLs are discharged to low level in the early timing of the active period by the short pulse BLDIS control timing operation. In the conventional sense amplifier, the simultaneous switching activation timing operation invokes the large coupling noise between the VSAREF node and the inner amplification nodes of the sense amplifiers. The coupling noise at VSAREF degrades the sensing voltage margin of the conventional sense amplifier. The merit of the proposed sense amplifier is almost removing the coupling noise at VSAREF from sharing with other sense amplifiers.

• Nuclear Engineering and Technology
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• 제54권1호
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• pp.326-342
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• 2022

Comparative analyses of a shield building subjected to a large commercial aircraft impact between decoupling method and coupling method are performed in this paper. The decoupling method is applying impact force time-history curves on impact area of the shield building to study impact damage effects on structure. The coupling method is using a model including aircraft and shield building to perform simulation of the entire impact process. Impact force time-history curves of the fuselage, wing and engine and their total impact force time-history curve are obtained by the entire aircraft normally impacting the rigid wall. Taking aircraft structure and impact progress into account some loading areas are determined to perform some comparative analyses between decoupling method and coupling method, the calculation results including displacement, plastic strain of concrete and stress of steel plate in impact area are given. If the loading area is determined unreasonably, it will be difficult to assess impact damage of impact area even though the accurate impact force of each part of aircraft obtained already. The coupling method presented at last in this paper can more reasonably evaluate the dynamic response of the shield building than the decoupling methods used in the current nuclear engineering design.

• The Journal of the Acoustical Society of Korea
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• 제25권3E호
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• pp.110-114
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• 2006

In a previous theoretical paper, we have derived a unified formula by considering 2-D coupled mode vibrations. The unified formula for electromechanical coupling coefficient of piezoelectric resonator was verified experimentally. The capacitance change near the resonant frequency was investigated to estimate the effective coupling coefficient of the resonator instead of the conventional method based on I-D model. The susceptance spectra were measured for the seven samples of piezoelectric resonator with different aspect ratio. Excellent agreement between theoretical and experimental results was obtained.

• Journal of Electrical Engineering and Technology
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• 제9권1호
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• pp.6-14
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• 2014

A new method to determine the total harmonic contributions of several customers and the utility at the point of common coupling is presented. The proposed method can quantify the individual harmonic impact of each suspicious harmonic source at the point of common coupling. The individual harmonic impact index is then used to assess the total harmonic contribution of each harmonic source. This index can be calculated by the results processed from instantaneous harmonic voltage and current phasor values. The results demonstrate the performance of the proposed method in terms of steady-state accuracy and response to time-varying operating conditions. The proposed index can be used for billing purposes to control harmonic distortion levels in power systems.

• 한국유체기계학회 논문집
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• 제17권4호
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• pp.70-75
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• 2014

In this paper a analysis method is presented to obtain the steady state dynamic response from the finite element based equations of a rotor-bearing system with initial deflection. The method has been applied to analyze the dynamic response of the two-shaft rotor-bearing system with rigid coupling offset in a heavy duty gas turbine-generator. Bumps in the dynamic response of each rotor system have been observed at each critical speed due to the effect of initial deflection for rigid coupling offset. And, the dynamic responses have been shown to reduce for operating condition changes from cold to hot.