• Particle and aerosol research
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• v.9 no.2
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• pp.69-78
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• 2013

In this study, the atmospheric aerosol concentration measured at different relative humidity levels was analyzed. Using an optical particle counter, PM10 and PM2.5 concentration as well as particle size distribution were measured and the relation between these size resolved data and relative humidity was studied. The results showed that mass concentration increases as relative humidity increases. The comparison between PM1, PM2.5 and PM10 showed that the fine particles grow more than coarse particles as relative humidity increases. The results also showed that PM10-2.5 and relative humidity do not show close correlation, which means that the mass increase of PM10 at high relative humidity is mainly due to the growth of PM2.5.

• Journal of the Korean Magnetics Society
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• v.6 no.1
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• pp.21-27
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• 1996

The effects of various manufacturing conditions on the characteristics of metal particle tape using ultra-fine metal powder were investigated. As functions of kneading conditions and milling solid contents. coating thickness, orientation, calender and curing conditions. various properties of the tapes were studied. By the consideration of physical and eletromagnetic properties of the tapes, optimum process conditions were determined. As a result of above investigations, we concluded that manufacturing processes were very important factor in addition to dispersion behavior of particles for achieving maximum properties of the metal particle tape.

• Phonetics and Speech Sciences
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• v.3 no.4
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• pp.55-62
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• 2011

This paper investigates whether listeners perceive a different level of politeness when the duration of the Korean sentence-final auxiliary particle '-yo' is varied. A total of 10 Korean sentences were manipulated by lengthening and shortening '-yo' by 10%, 20%, and 30%. The participants included native Korean speakers and Chinese and Japanese learners of Korean (n=10, respectively). They were asked to rate the level of politeness of the stimuli on a 9-point scale. It was found that Korean listeners perceived decreased politeness as the duration of '-yo' was shortened and increased politeness as it was lengthened. However, Chinese and Japanese listeners did not perceive a different level of politeness from the manipulated sentences. This finding suggests that it is important to teach L2 speakers that the duration of the auxiliary particle '-yo' plays a role in Korean listeners' perception of politeness.

• Journal of environmental and Sanitary engineering
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• v.6 no.1
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• pp.47-62
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• 1991

Yellow Sand Phenomena was observed from April 8 th to 10 th in 1990. During this period particle was collected to investigate the chacteristics of chemical composition of particulate by High Volume Air Sampler and Andersen Air Sa~npler in Seoul. During this period the particle concentration was 350 yg/$m^3$ and the anions, cations, and metal concentrations were increased and the orders of these were $S0_4\;^{-2}>N0_3\;^->Cl^->F^-, Na^+>Ca^{+2}>NH_4\;^+>Mg^{2+}>K^+$, and Fe>Al>Si>Zn>Pb respectively. The principal source of Yellow Sand were identified soil and sea salt. Mn used by the trace element of soil, the persentage of contribution from soil was calculated to be about 81.3% for the particle increased by Yellow Sand Phenomena. Also the principal chemical compounds of particle were estimate metals(Fe, Al, Si, Zn) oxides, $CaSO_4, NaSO_4, MgSO_4, NaC1, MgCl_2$ and $(NH_4)_2SO_4$.

• Journal of Korean Society on Water Environment
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• v.29 no.2
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• pp.170-175
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• 2013

Achieving very low phosphorus levels in treated wastewater will require the installation of additional treatment. Phosphorus removal experiments by chemical coagulation were carried out for the effluent of wastewater treatment plant in this study. TP (total phosphorus) or phosphate were highly related to the addition of PAC (poly aluminium chloride) which is one of the inorganic coagulants. But, organic polymer did not significantly affect the phosphorus removal efficiency. Polymer affected the flocculation of particle especially particle matter less than 10 micrometer so, the number of micro particles was decreased by polymer dose. Chlorination would not affect on chemical coagulation process and TP and turbidity could be effectively removed by the co-addition of PAC and polymer.

• Particle and aerosol research
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• v.8 no.2
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• pp.75-81
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• 2012

The strength of lumped cokes can be represented by some index numbers. Although some indexes are suggested, these indexes are not enough to enlighten fracture mechanism. To find essential mechanism, a computational way, discrete element method, is applied to the uniaxial compression test for cylindrical specimen. The cylindrical specimen is a kind of lumped particle mass with parallel bonding that will be broken when the normal stress and shear stress is over a critical value. It is revealed that the primary factors for cokes fracture are parallel spring constant, parallel bond strength, bonding radius and packing ratio the parallel bond strength and radius of the parallel combination the packing density. Especially, parallel spring constant is directly related with elastic constant and yield strength.

• Tribology and Lubricants
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• v.17 no.6
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• pp.417-426
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• 2001

The effect of silver particle introduction on the rolling friction of AISI 52100 steel pairs has been investigated. Experiments ware performed in dry conditions using a thrust bearing-type rolling test rig at a load range of 12-960 N and a sliding velocity range of 8-785 mm/sec with pure (99.99%) silver particles. Results showed that introduced silver particles formed transfer layers, which protected the virgin bearing surfaces and resulted in the low lolling friction. By changing the quantity of silver particles, transitions in the rolling friction were found. Results also showed that the variations in normal load and rolling speed also affected the rolling friction behavior. Analyses of SEM and EPMA showed that the formation the transfer layer was mainly governed by the silver particle quantity, normal load and rolling speed, and this resulted in the different behavior of rolling friction. In this study, it was found that the low and stable rolling friction was resulted from the, shakedown phenomena occurred at the silver transfer layer.

• Proceedings of the KIEE Conference
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• 1999.07e
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• pp.2399-2401
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• 1999

This paper indicate that phase resolved partial discharge pattern are investigated on PET films with semiconductor particle. In this study, we measured phase-resolved PD pattern and statistical parameter from PET specimens according to containing semiconductor particle. Measurement system is the conventional PD detector using digital signal processing technique. The relationship of semiconductor particle in PET film was discussed through the difference of $\psi$-q-n distribution and statistical analysis.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.7 no.3
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• pp.521-527
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• 1995

The average particle deposition velocity toward a vertical wafer surface in a vertical airflow chamber was measured by a wafer surface scanner(PMS Model SAS-3600). Polystyrene latex(PSL) spheres with diameters between 0.3 and $0.8{\mu}m$ were used. To examine the effect of the airflow velocity on the deposition velocity, experiments were conducted for three vertical airflow velocities ; 20, 30, 50cm/s. Experimental data of particle deposition velocity were compared with those given by prediction model suggested by Liu and Ahn(1987).

• Particle and aerosol research
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• v.11 no.3
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• pp.77-85
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• 2015

A Belousov-Zhabotinsky reaction in a liquid-liquid system under microwave radiation was observed under non-stirring conditions. To control this non-equilibrium reaction, nano-particle, which is active under microwave irradiation, was added to the solution. Color changes of the solution during the oscillatory reaction were found to be influenced by the irradiation power although the droplet temperature was equal to the temperature of surrounding oil. During the irradiation, the period of oscillation became shorter because the reaction rate was faster. It could also be observed that there is possibility to eliminate oscillatory behaviors of the reaction using higher power of microwave. The possibility of controlling non-linear reaction using microwave was shown since microwave can easily travel through oil phase and reach water phase.