• Magazine of the Korea Concrete Institute
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• v.6 no.5
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• pp.131-139
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• 1994

The min aim of thls study was to evaluate the effect of particle slze of the fly ash as a cement additive. Experimental work was carried out with three different sizes of fly ash. 18.58, 8.95 and 4.02{$mu}m$ in average radius. Namely, the effect of particle size variation of fly ash on the physical properties of cement paste was investigated. The jluidity was decreased with increasing the addition of fly ash to cement paste regardless of the particle size variation. The decrement of the fluidity of the pulverized fly ash was higher than that of the spherical fly ash. On the other hand, the pozzolan reactivity increased with lowering particle size. In the case of specimens with 5% up to 10% addition of fly ash having a particle size of 4.02{$mu}m$. the compressive strength was increased as compared with the plain specimens before curing for 28 days and showed higher value above 800kg /$cm^2$ when cured for 60 days.This increased compressive strength was ascribed to both the closer packlng of fine particles and the pozzolan reactivity of fly ash. These results were comfirmed by measuring both the porosity of the specimens and Ca(OH ), contents remained in specimens. This work showed that could be effectively ut~lized as a blending material without any de crease in the strength of early hydration stage if we can control the particle size of fly ashes by sizing or pulverizing.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.1152-1157
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• 2004

Temporal behavior of the laser induced incandescence (LII) signal is often used for soot particle sizing, which is possible because the cooling behavior of a laser heated particle is dependent on the particle size. In present study, LII signals of soot particles are modeled using two non-linear coupled differential equations deduced from the energy- and mass-balance of the process. The objective of this study is to see the effects of particle size, laser fluence on soot temperature characteristics and cooling behavior. Together with this, we focus on validating our simulation code by comparing with other previous results. Results of normalized LII signals obtained from various laser fluence conditions showed a good agreement with that of Dalzell and Sarofim's. It could be found that small particles cool faster at a constant laser fluence. And it also could be observed that vaporization is dominant process of heat loss during first 100ns after laser pulse, then heat conduction played most important role while thermal radiation had little influence all the time.

• Journal of Mechanical Science and Technology
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• v.18 no.6
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• pp.879-894
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• 2004

The image processing technique is simple and, in principle, can handle particles with various shapes since it is based on direct visualization. Moreover, a wide measurement area can be covered with appropriate optical arrangement. In the present paper, various techniques of image processing for sizing and counting particles are reviewed and recent developments are introduced. Two major subjects are discussed in detail: identification of particles (i.e., boundary detection and pattern recognition) and determination of in-focus criteria. Finally, an overall procedure for image processing of spray particles is suggested.

• Journal of The Institute of Information and Telecommunication Facilities Engineering
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• v.11 no.2
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• pp.34-38
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• 2012

In this paper, the particle swarm optimization (PSO) algorithm is adopted to design a modified ring-slot type patch rectenna with a resonance frequency of 2.45GHz. In order to accomplish minimization of dimensions and circular polarization (CP) and harmonic suppression, axial direction slits and side-cuts are added to the patch of the ring. The PSO manipulated this kind of multi-dimensional problem very well, and as a result, the designed rectenna shows a desirable performance of return loss of 21.36dB and axial ratio of 2.92dB at the frequency of 2.45GHz with compact sizing.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.1140-1145
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• 2004

Laser-induced incandescence (LII) is introduced as a valuable tool for the characterization of nanoparticles in flame environments. This technique is based on the heating of the particles by a short laser pulse and the subsequent detection of the thermal radiation. It has been applied successfully for the investigation of soot in different fields of application. The evaluation of the temporal decay of the laser-induced incandescence (LII) signal from soot particles is introduced as a technique to obtain two-dimensional distributions of particle sizes and is applied to a laminar diffusion flame. This novel approach to soot sizing exhibits several theoretical and technical advantages compared with the established combination of elastic scattering and LII, especially as it yields absolute sizes of primary particles without requiring calibration. With this technique a spatially resolved 2-D measurement of soot primary particle sizes is feasible in a combination process form the ratio of emission signals obtained at two delay times after a laser pulse, as the cooling behavior is characteristic of particle size.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.39 no.4
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• pp.29-37
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• 2007

The effects of latex particle size, basis weight of base paper and coating color concentration on the printing quality of coated paper were investigated. Coating colors were prepared with five types of latexes having different particle sizes. Coated papers were produced with high solid coating colors and with low solid coating colors in a industrial coater, respectively. In high solid coating colors, rheology modifier was used and GCC content was high. It was concluded that, in order to control binder migration and hence print mottle, latex particle sizes shall be controlled as well as formation, sizing degree and roughness of basis paper.

• Bulletin of the Korean Chemical Society
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• v.12 no.3
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• pp.322-328
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• 1991

We have studied a characterization method of accurate size of spherical particles by fitting experimental light scattering profile to the rigorous theoretical scattering function. An efficient software has been developed for computation of the theoretical scattering function and regression analysis. A light scattering instrument has been built and the necessary data acquisition and analysis are carried out by use of a personal computer with an emphasis on the reduction of analysis and time aiming that this study will be extended toward a development of a practical particle sizing apparatus. The performance of the instrument and the software has been evaluated with latex spheres and found to be satisfactory.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.29 no.9 s.240
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• pp.1022-1031
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• 2005

Temporal behavior of the laser induced incandescence (LII) signal is often used for soot particle sizing, which is possible because the cooling behavior of a laser heated particle is dependent on the particle size. In present study, LII signals of soot particles are modeled using two non-linear coupled differential equations deduced from the energy- and mass-balance of the process. The objective of this study is to obtain an appropriate calibration curve for determining primary particle size by comparing the gated signal ratio and double-exponential curve fitting methods. Not only the effects of laser fluence and gas temperature on the cooling behavior but also heat transfer mechanisms of heated soot particle have been investigated. The second-order exponential curve fitting showed better agreements with the LII signals than the gated signal ratio method which was based on the lust-order exponential curve fit. And the temporal decay rate of the LII signal and primary particle size showed nearly linear relationship, which was little dependent on the laser fluence. And it also could be reconfirmed that vaporization was dominant process of heat loss during first loons after laser pulse, then heat conduction played most important role while thermal radiation had little influence all the time.

• Transactions of the Korean Society of Automotive Engineers
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• v.18 no.4
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• pp.99-106
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• 2010

A piezo-driven injector was applied with a purpose to evaluate the effect of induced voltage on spray characteristics. For this, injection rate, macroscopic imaging, ambient gas entrainment and particle sizing were carried out. It was shown that initial slope of injection rate was steeper as induced voltage increased, while slope of injection rate became mostly constant with fully opened needle. From macroscopoic imaging, longer spray tip penetration was produced with higher induced voltage. Moreover, wider spray angle was detected in the early stage of spray development, when higher induced voltage was applied. Ambient air entrainment rate was increased and particle size was reduced with higher induced voltage.

• Journal of Power Electronics
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• v.12 no.5
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• pp.830-841
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• 2012

Active power filters (APF) can be employed for harmonic compensation in power systems. In this paper, a fuzzy based method is proposed for identification of probable APF nodes of a radial distribution system. The modified adaptive particle swarm optimization (MAPSO) technique is used for final selection of the APFs size. A combination of Fuzzy-MAPSO method is implemented to determine the optimal allocation and size of APFs. New fuzzy membership functions are formulated where the harmonic current membership is an exponential function of the nodal injecting harmonic current. Harmonic voltage membership has been formulated as a function of the node harmonic voltage. The product operator shows better performance than the AND operator because all harmonics are considered in computing membership function. For evaluating the proposed method, it has been applied to the 5-bus and 18-bus test systems, respectively, which the results appear satisfactorily. The proposed membership functions are new at the APF placement problem so that weighting factors can be changed proportional to objective function.