• Proceedings of the KIEE Conference
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• 2006.07b
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• pp.685-686
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• 2006

The excitation system of 500MVA short-circuit generator is very important because of operation of various condition, for example, (over) load switching, short-time current, short-circuit current, etc. This paper introduces a feature of excitation system of 500MVA short-circuit facilities and the function and construction of each part.

• Proceedings of the KIEE Conference
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• summer
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• pp.896-898
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• 2004

The lagging reactive power should be supplied for the excitation of isolated squirrel-cage induction generators by external circuit. This paper deals with a technique to drive the equations for analysis of the excitation characteristics and performance of an isolated squirrel-cage induction generator from the conventional equivalent circuit of induction machine, transform the equations into d-q coordinates to use vector control technique, and carry out the simulation of an induction generator system with various conditions using MATLAB. The results of the simulation indicate that moderate reactive power can be controlled effectively to maintain constant voltage over a wide range of the rotor speeds and loads.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.989-990
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• 2007

The excitation system of 500 MVA short-circuit generator is very important because of operation of various condition, for example, (over) load switching, short-time withstand current, short-circuit making and breaking current, etc. This paper introduces a feature of excitation system of 500MVA short-circuit generator and the function and construction.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2006.03a
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• pp.503-510
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• 2006

Seismic control performance of MR dampers, which have severe nonlinearity, differs with respect to the dynamic characteristics of an earthquake such as magnitude, frequency and duration. In this study, the effects of excitation characteristics on the equivalent linear system of a building structure with an MR damper are investigated through numerical analysis for artificial ground motions generated from different response spectrums. The equivalent damping ratio of the structure with an MR damper is calculated using Newmark and Hall's equations for ground motion amplification factors. It is found that the equivalent damping ratio of the structure with the MR damper is dependent on the ratio of the maximum friction force of the MR damper over excitation magnitude. Frequency contents of the earthquake ground motion affects the equivalent damping ratio of long-period structures considerably. Also, additional damping effect caused by interaction between the viscousity and friction of the MR damper is observed.

• Bulletin of the Korean Chemical Society
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• v.16 no.10
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• pp.972-976
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• 1995

A trace amount of 4-biphenylcarboxylate having a pre-twisted biphenyl moiety was attached to a poly(methyl methacrylate) side chain and the fluorescence properties of the chromophore were investigated in various solvents such as ethyl acetate and butyl chloride. At room temperature, the polymer exhibited a distinct red shift of the short wavelength emission (325 nm) and an enhanced emission intensity around 430 nm upon excitation at the absorption red edge. The temperature dependence of the intensity ratio (R) of the 325 nm emission to the 430 nm emission was observed when exciting at the red edge over the temperature range between -20 and 60 ℃. However, the temperature dependence was not observed when exciting at the shorter wavelength. The Arrhenius plot of the R value shows the activation energy of 6.0 kJ/mol which is in good agreement with the energy required for the twist of the biphenyl moiety. Together with the results of red edge excitation effects it was concluded that the pre-twisted geometry of the biphenyl moiety is preserved by the restriction of the polymer chain to facilitate the formation of the twisted intramolecular charge transfer (TICT) state upon excitation.

• Journal of the Optical Society of Korea
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• v.17 no.1
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• pp.81-85
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• 2013

A miniaturized fluorescence detection system based on total internal reflection (TIR) configuration, which is applicable to detecting the presence of biological materials labeled with fluorescence dye in micro total analysis systems (${\mu}TAS$), is proposed. In conventional fluorescence testing and analysis devices, interference between the excitation light beam and the emitted light from dyes is unavoidable. This paper presents a fluorescence detection system based on TIR configuration that allows the excitation light beam and the emitted light to be spatially perpendicular to each other so as to minimize the interference where fluorescence emission is detected at the orthogonal angle to the excitation beam. We achieved the limit of detection of about 5 nmol/L with a high linearity of 0.994 over a wide range of 6-FAM mol concentration, being comparable to that in earlier studies.

• Journal of Mechanical Science and Technology
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• v.16 no.9
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• pp.1040-1053
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• 2002

This research deals with the influence of nonlinearities associated with impact and sliding upon the rocking behavior of a rigid block, which is subjected to two-dimensional horizontal and vertical excitation. Nonlinearities in the vibration were found to depend strongly on the effect of the impact between the block and the base, which involves an abrupt reduction in the system's kinetic energy. In particular, when sliding occurs, the rocking behavior is substantially changed. Response analysis using a non-dimensional rocking equation was carried out for a variety of excitation levels and excitation frequencies. The chaos responses were observed over a wide response region, particularly, in the cases of high vertical displacement and violent sliding motion, and the chaos characteristics appear in the time histories, Poincare maps, power spectra and Lyapunov exponents of the rocking responses. The complex behavior of chaotic response, in phase space, is illustrated by the Poincare map. The distribution of the rocking response is described by bifurcation diagrams and the effects of sliding motion are examined through the several rocking response examples.

• Journal of the Society of Naval Architects of Korea
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• v.54 no.6
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• pp.447-452
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• 2017

A rigid body supported by 4 linear springs has been analyzed, to investigate the effects of eccentricities on the vibration responses for naval shipboard equipments supported by elastic mounts. Considering mount eccentricity (the location of the center of spring reaction forces relative to the mass center) and excitation force eccentricity (the location of the center of the excitation force relative to the mass center), the vibration phenomena have been formulated and discussed. Also, the effects of the eccentricities have been evaluated and discussed for the elastically mounted naval shipboard equipment. Results show that the mount eccentricity has little effects on the structure-borne noise above the natural frequency of the system, however the excitation force eccentricity has significant effects all over the frequency range.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07a
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• pp.151-155
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• 2002

This paper presents a micro fluxgate magnetic sensor in printed circuit board (PCB). The fluxgate sensor consists of five PCB stack layers including one layer magnetic core and four layers of excitation and pick-up coils. The center layer as a magnetic core is made of a micro patterned amorphous magnetic ribbon with extremely high DC permeability of ∼100,000 and the core has a rectangular-ring shape. The amorphous magnetic core is easily saturated due to the low coercive field and closed magnetic path for the excitation field. Four outer layers as an excitation and pick-up coils have a planar solenoid structure. The chip size of the fabricated sensing element is 7.3${\times}$5.7m㎡. Excellent linear response over the range of -100${\mu}$T to +100${\mu}$T is obtained with 540V/T sensitivity at excitation square wave of 3V$\_$P-P/ and 360kHz. The very low power consumption of ∼8mW was measured. This magnetic sensing element which measures the lower fields than 50${\mu}$T, is very useful for various applications such as: portable navigation systems, military research, medical research, and space research.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.8
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• pp.702-707
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• 2002

This paper presents a micro fluxgate sensor in printed circuit board (PCB). The fluxgate sensor consists of five PCB stack layers including one layer magnetic core and four layers of excitation and pick-up coils. The center layer as a magnetic core is made of a micro patterned amorphous magnetic ribbon and the core has a rectangular-ring shape. The amorphous magnetic core is easily saturated due to the low coercive field and closed magnetic path for the excitation field. Four outer layers as an excitation and pick-up coils have a planar solenoid structure. The chip size of the fabricated sensing element is 7.3$\times$5.7$\textrm{mm}^2$. Excellent linear response over the range of -100$\mu$T to +100$\mu$T is obtained with 540V/T sensitivity at excitation square wave of 3 $V_{p-p}$ and 360kHz. The very low power consumption of ~8mW was measured. This magnetic sensing element, which measures the lower fields than 50$\mu$T, is very useful for various applications such as: portable navigation systems, military research, medical research, and space research.h.