• Proceedings of the IEEK Conference
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• 2002.07a
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• pp.527-530
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• 2002

The frequencies for HAPS used in fixed wireless access are allocated in the millimeter wave bands. The systems using these frequencies can have a serious impact on the radio communication qualities due to rain. In this paper, we compare the specific rain attenuation using CM(combined) raindrop size distribution with those using different sevral raindrop size distributions for the frequency bands 28/48㎓. The rain attenuations using CM raindrop size distribution for the path between the earth and HAPS platform according to the elevation angle are described.

• Proceedings of the IEEK Conference
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• 2001.09a
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• pp.455-458
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• 2001

In this paper, a new license plate recognition method using the morphological size distribution functions and color images is proposed. The proposed method consists of two steps. The first step is license plate extraction process using the plate color and step edge information in the license plate. The second step is the extraction of character feature vectors using the morphological size distribution functions and character recognition process using the MLP(multilayer perceptron). By the use of morphological size distributions functions, the error that may occur during the character region extraction process is lessened and the recognition performances are improved by the decrease of feature vector dimension.

• Journal of the Korean Operations Research and Management Science Society
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• v.18 no.3
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• pp.179-186
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• 1993

We derive the arbitrary time point system size distribution of M/ $G^{B}$1 queue in which late arrivals are not allowed to join the on-going service. The distribution is given by P(z) = $P_{4}$(z) $S^{*}$ (.lambda.-.lambda.z) where $P_{4}$ (z) is the probability generating function of the queue size and $S^{*}$(.theta.) is the Laplace-Stieltjes transform of the service time distribution function. We also derive the distribution of the service siez at arbitrary point of time. time.

• Journal of ILASS-Korea
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• v.20 no.3
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• pp.175-180
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• 2015

A series of sprinkler discharging tests was conducted to measure the droplet size and its distribution of residential fire sprinkler heads. Droplet sizes in sprinkler spray were measured using a laser diffraction method for the flush, circular and pendent type sprinkler head. In this study, the $D_{v,50}$ of the flush type sprinkler heads were ranged between $530{\sim}1040{\mu}m$ and those of circular and pendent type were $988{\mu}m$ and $916{\mu}m$, respectively. The measured cumulative volume distributions were followed by a combination of the log-normal and Rosin-Rammler distribution which is widely used in the computational fire analysis and the parameters of distribution function were obtained from the best fit line through the measured data.

• Archives of Pharmacal Research
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• v.12 no.3
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• pp.214-218
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• 1989

Atmospheric particulate matters (A. P. M. ) were collected on quartz-fiber filters from March 1985 to May 1986, using the Andersen high-volume air sampler and contents of six heavy metals (Fe, Mn, Cu, Zn, Pb Ni) in the A. P. M. were determined by atomic absorption spectrophotometry. These heavy metals were divided into the three groups with respect to their particle size distribution. Fe and Mn were mainly associated with coarse particles (diameter > 2.0 $\mu$m), but Pb and Ni were related fine particles (diameter < 2.0 $\mu$m). Cu and Zn had mized size distributions in both of them. In the seasonal variation of heavy metals, the contents of Fe and Mn in spring and Ni and Pb in winter were higher than any other season. There were high mutual correlation between Fe and Mn coarse particles, and between Pb and Ni in fine particles.

• Transactions of the Korean Society of Automotive Engineers
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• v.7 no.5
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• pp.31-39
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• 1999

A good atomization in uniform size brings the elevation of thermal efficiency in spray combustion, the beautiful painting on surfaces, and the economical sprinkling of chemicals. Ultrasonic atomization has been expected as a good uniform atomization mechanism due to its uniform size distribution. Influx, load, and physical properties of liquids are the effecting factors to atomize liquids. In this study, distilled water and city water are selected as reference liquids and gasoline, kerosene, and petroleum as fuel liquids. Characteristics and affinity to get the maximum effect for the ultrasonic atomization are observed by using the two ultrasonic transducers with 28kHz and 2MHz. Results show that the size distributions of liquid spray dorplet by the direct vibration method prevail over those by the aerosol method in uniform droplet size and as a whole, sizes of spray liquid droplets are increased slightly according to increasing influx in the direct vibration method and quantities of spray droplets in the aerosol method decreasing according to increasing liquid load h.

• Transactions of the Korean Society of Automotive Engineers
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• v.5 no.6
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• pp.167-174
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• 1997

The penetration depth and the size distribution of the droplets of fuel sprays are important in the operation of spark-ignition MPI engines. A fluorescence/scattering image technique for droplet sizing was applied to measure th edroplet size distribution in non-evaporating gasoline sprays. The fluorescence and scattering lights were imaged simultaneously by the two-dimensional visualization system composed of a laser sheet, a doubling prism, optical filters, and a CCD camera. Quantitative droplet size distributions were extracted from evaluating the ratio of the two light densities. The mean droplet size measured by the fluorescence/scattering technique was compared with the result obtained by the enlarged photographs of droplets. The fluorescence/scattering image technique also gives the useful information of the characteristics of droplet impingement in a inclined wall.

• Journal of Korean Society for Atmospheric Environment
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• v.12 no.1
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• pp.67-77
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• 1996

Total suspended particulate matters (TSP) were collected based on a size segregation method by a cascade impactor for 6 consecutive years (form Dec. 1989 to sep. 1994) in the Kyung Hee University-Suwon Campus, and 6 trace metals (Ca, Si, Fe, Pb, Cu, Zn) were determined by an x-ray fluorescence spectroscopy. Total number of samples collected during the study are 118 sets and each set of sample comsists of 9 filters. The levels of TSP and 6 trace metals were then used to examine seasonal and annual variations with respects to their size distributions. For statistical analyses, raw data were initially transformed by both logarithmic and root transformating to approximately normalize them, and then size distribution functions for each trace element were separately developed season-to-season by a regression analysis in order to obtain maximum amount of physical information, Subsequently, each developed model was verified by comparing with supervised data collected on 1994. The result showed that each prediction model was in good agreement except the fall, partly due to lack of the data collected on fall, 1994.

• Journal of Korean Society for Atmospheric Environment
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• v.15 no.5
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• pp.677-685
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• 1999

Aerosol mass size distributions were measured at Kosan, Cheju Island in April 1998 and their compositions were analyzed. Microorifice Uniform Deposit Impactor(MOUDI) was used to collect aerosols. Sulfate and ammonium ions were predominatly present at fine mode of the aerosols while nitrate, chloride, and metal ions were mostly at coarse mode. Based on the size distribution of nitrate, it is suggested that most nitrate were from gas to particle conversion on coarse particles. Non-sea salt(nss) fraction of sulfate accounted for more than 90% of total sulfate mass concentration. In general, ion concentrations in this study are lower than those measured at the same site from the previous studies. Ion balance and chloride ion levels indicates that there had been anthropogenic chloride emission sources near to the site during the measurements.

• Journal of the Korean Ceramic Society
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• v.46 no.5
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• pp.472-477
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• 2009

Monodisperse spherical $SiO_2$ particles of various sizes ($\sim$350 nm and $\sim$800 nm) and size distributions were synthesized from TEOS and MTMS. The particle size and size distribution were controlled by changing the volume ratio of water to ethanol and the reaction temperature. Narrow-sized $SiO_2$ particles with $\sim$3% size distribution were obtained. Self-assembly of the $SiO_2$ particles for photonic crystals were performed by the solvent evaporation method. The number of ordered $SiO_2$ layers can be controlled by changing the amount of the dispersed $SiO_2$ volume fraction in the solvent.