• Proceedings of the KOSOMBE Conference
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• v.1997 no.11
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• pp.154-160
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• 1997

By their rapid and periodic actions, the cilia of the human respiratory tract play an important role in clearing inhaled noxious particles. Based on the automated image-processing technique, we studied ciliary beat frequency (CBF) objectively and quantitatively. Microscopic ciliary images were transformed into digitized gray ones through an image-grabber, and from these we extracted signals or CBF. By means of a FFT, maximum peak frequencies were detected as CBFs in each partitioned block or the entire digitized field. With these CBFs, we composed distribution maps visualiy showing the spatial distribution of CBFs. Through distribution maps of CBF, the whole aspects of CBF changes or cells and the difference of CBF of neighboring cells can be easily measured and detected. Histogram statistics calculated from the user-defined polygonal window can show the local dominant frequency presumed to be the CBF of a cell or a crust the region includes.

• Journal of the Korean Society for Heat Treatment
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• v.19 no.5
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• pp.249-256
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• 2006

Structural studies have been performed on precipitation hardening found in $L1_2$ ordered ${\gamma}^{\prime}-Ni_3(Al,Ti)$ alloys using transmission electron microscopy. A uniform solid solution of ${\gamma}^{\prime}-L1_2$ ordered phase supersaturated with Ni can be obtained by solution annealing in a suitable temperature range. The ${\gamma}^{\prime}$ phase hardens appreciably by the fine precipitation of disordered ${\gamma}$. The shape of ${\gamma}$ precipitates formed during aging is initially spherical or round-cubic and grow into platelets as aging proceeds. High resolution electron microscopy revealed that the ${\gamma}$ precipitates are perfectly coherent with the matrix ${\gamma}^{\prime}$ as long as the ${\gamma}$-precipitates are plates. The loss of coherency initiates by the introduction of dislocations at the ${\gamma}/{\gamma}^{\prime}$ interface followed by the step formation at the dislocations. The ${\gamma}$ precipitates become globular after the loss of coherency. The strength of ${\gamma}^{\prime}-Ni_3(Al,Ti)$ increases over the temperature range of experiment by the precipitation of fine ${\gamma}$ particles. The peak temperature where a maximum strength was obtained shifted to higher temperature.

• Proceedings of the KIEE Conference
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• 2005.07c
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• pp.1989-1991
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• 2005

Lithium titanium oxide as anode material for energy storage prepared by novel synthesis method. $Li_4Ti_5O_{12}$ based spinel-framework structures are of great interest material for lithium-ion batteries. We describe here $Li_4Ti_5O_{12}$ a zero-strain insertion material was prepared by novel sol-gel method and by high energy ball milling (HEBM) of precursor to from nanocrystalline phases. According to the X-ray diffraction and scanning electron microscopy analysis, uniformly distributed $Li_4Ti_5O_{12}$ particles with grain sizes of 100nm were synthesized. Lithium cells, consisting of $Li_4Ti_5O_{12}$ anode and lithium cathode showed the 173 mAh/g in the range of $1.0{\sim}3.0V$. Furthermore, the crystalline structure of $Li_4Ti_5O_{12}$ didn't transfer during the lithium intercalation and deintercalation process.

• Korean Journal of Metals and Materials
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• v.49 no.1
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• pp.46-51
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• 2011

Real-time formation of $L1_0$ phase of FePt nanoparticles in the gas phase during ultrasonic-spray pyrolysis is first discussed in the present study. Without any post heat treatment, $L1_0$ phase of FePt nanoparticles appeared at the temperature above $900^{\circ}C$ in the gas phase synthesis. X-ray diffractometry (XRD) and transmission electron microscopy (TEM) studies revealed that FePt nanoparticles less than 10 nm in size contained small volume of $L1_0$ fct phase. However, in other samples obtained at the temperature below $900^{\circ}C$, iron oxide phase co-existed and no evidence of phase transformation was found. Thus, it is anticipated that the time of flight of particles required for crystallization and phase transformation was extended according to the increase of the collision rate. Finally, magnetic properties represented by coercivity and saturation magnetization and functional groups on the particle surface were discussed based on VSM and FT-IR results.

• Journal of Plant Biotechnology
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• v.31 no.1
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• pp.13-17
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• 2004

To improve transformation efficiency, the callus of Lilium lancifolium Thunb. were bombarded by particles coated with pIG 121 Hm which include NPT II and GUS genes, and then cocultivated with Agrobacterium tumefaciens EHA101 which contain pIG121Hm binary vector, carrying neomycin phosphotransferase (NPT II) and $\beta$-Glucuronidase (GUS) genes. Three days after cocultivation with Agrobacterium tumefaciens and particle bombardment, the callus clusters were transferred to MS medium containing 1mg/L 2,4-D, 0.1mg/L BAP, 100mg/L kanamycin and 200mg/L carbenicillin. Four weeks after transfer to the selection medium, GUS expression was detected and PCR analysis revealed the presence of NPT II fragment of the expected size (700 bp) in the transformed callus. The GUS expression from Agrobacterium-mediated transformants after particle bombardment increased to over 3-folds compared with that of callus cocultivated with Agrobacterium tumefaciens without particle bombardment. The callus clusters containing kanamycin resistant gene were transferred to MS medium containing 1mg/L NAA and 1mg/L BAP. Somatic embryos were developed in four weeks and microbulbs expressing GUS were formed.

• Economic and Environmental Geology
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• v.27 no.1
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• pp.93-100
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• 1994

This study examined the mechanisms of lead transport in the groundwater system and those of irregular detections in groundwater in Door County, Wisconsin. During the spring recharge period in 1991, water-level movement and water-quality change were monitored from two monitoring wells equipped with three piezometers each and from five house wells, respectively. Water-level responses to recharge events were fast with a relatively short lag time ranging from 3 to 10 days, indicating that recharge of groundwater occurs through the high hydraulic conductivity (K) zones in the Silurian dolomite aquifer system. Lead was detected only on particles filtered from groundwater, but not in dissolved state. Concentrations ranged from 0.2 to $7.1{\mu}g/mg$, converted into the total lead concentration in groundwater ranging from $0.3{\mu}g/l$ to $4.7{\mu}g/l$. A lag time between recharge events and peak particle movement at the sampled wells was estimated to range from 19 to 22 days. Due to the particulate nature of lead in groundwater, only the wells connected with the high K zones detect lead, causing the spatial variation. In a given well, lead concentration varies at different sampling times due to the variation in the initial amounts of lead-carrying particles introduced into the groundwater system during recharge events, the lag in particle transport and the dispersion of lead-carrying particles along the advective flowpaths.

• Food Engineering Progress
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• v.13 no.4
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• pp.269-274
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• 2009

The main objective of this study was to establish optimum condition of wet grinding process for manufacturing microparticulated seaweed calcium. Process parameters such as concentration of forming agent, rotor speed, bead size, feed rate, and grinding time were adapted during wet-grinding of seaweed calcium. The particle size range of the raw seaweed calcium was 10-20 $\mu$m. The calcium particles were reduced to under 1 $\mu$m as nano scale after grinding. Gum arabic was suitable for forming agent and 5%(w/v) concentration was the most effective in grinding efficiency. A wet-grinding process operated at 4,000 rpm rotor speed, 0,4 mm bead size, and 0.4 L/hr feeding rate, respectively, produced less than 600 mm(>>90%)-sized particles. In batch systems, 8 cycles of grinding showed higher efficiency, but 20 min of grinding time in continuous processing was more efficient to reduce particle size than the batch processing. Based on the result, the optimum conditions of the wet grinding process were established: operation time of 20 minutes, rotor speed of 4,000 rpm, bead size of 0.4 mm, feed rate of 40 mL/min and 30% mixing ration with water. The size of the resulting ultra fine calcium particles ranged between 40 and 660 mm.

• Korean Chemical Engineering Research
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• v.54 no.5
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• pp.706-711
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• 2016

Characteristics of solid circulation rate in the liquid-solid circulating fluidized beds with viscous liquid medium were investigated. Effects of primary and secondary liquid velocities, particle size, liquid viscosity and height of solid particles piled up in the solid recycle device on the solid circulation rate were considered. The solid circulation rate increased with increasing primary and secondary liquid velocities, liquid viscosity and height of solid particles in the downcommer, but it decreased with increasing particle size. The particle rising velocity in the riser decreased with increasing the ratio of $U_{L1}/U_{L2}$ and particle size. The slip velocity of liquid and particle, $U_L/U_S$, decreased with increasing liquid viscosity but it increased with increasing particle size. The values of solid circulation rate were well correlated in terms of operating variables and dimensionless groups.

• Journal of the Korean Wood Science and Technology
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• v.30 no.4
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• pp.106-113
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• 2002

This research was performed to investigate the effect of moulding conditions on properties of the table top for student desk manufactured by wood waste materials. The table top manufactured using the mat mixed properly with fine particles and coarse particles generally showed better physical properties than those manufactured using either fine particles or coarse particles did/ Especially, highest performance for overlaying was observed when fine particles were used for face layer and coarse particles were used for core layer. The internal bond (IB) strength, the bending strength and thickness swelling increased with the increase of density. Most of physical properties were improved with the increase of hot pressing temperature. The best physical properties were found at 190℃ when the first hot pressing and the second hot pressing times were two minutes. However, the effect of the second hot pressing time of two minutes on the physical properties was not markedly different from that of one minute. This result suggests that the second hot pressing time of one minute is enough to increase the productivity in manufacturing the table top with the least decrease of the physical properties.

• Journal of Bio-Environment Control
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• v.28 no.4
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• pp.454-460
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• 2019

The purpose of this study is to analyze the distribution characteristics of mist spray particle size by devising a rotary mist spraying device to develop the evaporative salt water desalination system. The rotary mist spraying device was consisted of a BLDC sirocco fan, a spinning fan, a fan fixed shaft and a salt water supply device etc. In this study we analyzed the characteristics of spray particle size and distribution according to the variation of sirocco fan surface roughness(Ra, ${\mu}m$), revolutions(rpm) and salt water flow rate(mL/min). When sirocco fan surface roughness(Ra) was in the range of $0.27{\sim}7.65{\mu}m$, the spray particle size was $0.117{\sim}1.360{\mu}m$. And then more than 90% of spray particles were found to be less than $0.50{\mu}m$. When sirocco fan surface roughness(Ra) was in the range of $12.70{\sim}22.84{\mu}m$, the spray particle size was $2.51{\sim}184.79{\mu}m$ and more than 98% of spray particles were found to be less than $13.59{\mu}m$. To analyze the effect of fan rotation speed on the size and distribution of spray particles, when surface roughness Ra was fixed $0.27{\mu}m$ and fan rotation speed and salt water flow rate was respectively changed at 3,800~5,600 rpm and 2.77~8.28 mL/min, spray particle size was $0.314{\sim}0.541{\mu}m$. And when salt water flow rate was 9.74 mL/min and fan rotation speed was 3,800~5,200 rpm, spray particle size was in the range of $29.29{\sim}341.46{\mu}m$ and in case of 5,600 rpm more than 98.23% of spray particles were in the range of $2.51{\sim}13.59{\mu}m$.