• Journal of Korean Society for Atmospheric Environment
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• v.31 no.2
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• pp.118-130
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• 2015

Fine dust containing iron compounds is of current interests in metro subway as well as large scale industries including iron manufacturing and smelting works. This work attempts to find a new design of magnetic filter module for iron dust capture. It simulated the vertical rectangular duct with metal mesh which might promote electric fields in the duct space. A lab test using coal fly ash composed of 8.66% Fe with the most form of $Fe_3O_4$ and $Fe_2O_3$ showed capability of magnetic collection. It showed the capture efficiency with 80~93% for $PM_{2.5}$ depending on magnetic intensity. Ferromagnetic wire mesh contributed up to 50% of collection increment.

• Journal of KSNVE
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• v.9 no.3
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• pp.600-606
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• 1999

A reactive type acoustic filter is developed based on the phase cancellation effect which is occurring in the plane wave propagation through the two paths where the cross sectional areas are reversely changing. The theory is experimentally validated by the use of a cylindrical duct and an inserted hollowed cone of which vertex part is eliminated. Noise attenuation and the filtered frequency are dependent on the area variation and the effective length of the filter. Experimental comparison shows that the filtered frequencies of 1st and 2nd mode are lower than the analytical prediction due to the mass loading effects, and the 3rd mode is in good agreement. The proposed filter can be applied as an in-duct noise filter for improving the sound quality in a narrow space for various industrial applications.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.23 no.8
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• pp.1063-1071
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• 1999

Fine grid calculations are reported for the developing turbulent flow in a curved duct of square cross-section with a radius of curvature to hydraulic diameter ratio ${\delta}=Rc/D_H=3.357 $ and a bend angle of 720 deg. A sequence of modeling refinements is introduced; the replacement of wall function by a fine mesh across the sublayer and a low Reynolds number algebraic second moment closure up to the near wall sublayer in which the non-linear return to isotropy model and the cubic-quasi-isotropy model for the pressure strain are adopted; and the introduction of a multiple source model for the exact dissipation rate equation. Each refinement is shown to lead to an appreciable improvement in the agreement between measurement and computation.

• Journal of Animal Environmental Science
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• v.13 no.3
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• pp.195-200
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• 2007

Management of odors is essential to swine industry in the Republic of Korea. This study was conducted to evaluate the odor removal efficiency of biofilter ducting systems. Rice straw and auto clave concrete(ALC) were used as filter medium. The ventilation fans(5 units, diameter: 500 mm) at the side wall of a growing pig housing were connected to a biofilter using a duct. The size of a biofilter is $2.5{\times}2{\times}1.2(W{\times}L{\times}H)$. The air velocities at the 300 mm above rice straw and ALC were 0.77 and 0.56 m/s, respectively. Ammonia concentration at the outlet of rice straw and ALC media were 2 and 3 ppm, respectively. Dust concentrations were also measured. The dust concentrations of rice straw and ALC were 93, $32\;mg/m^3$, respectively. There was no significant difference between filter mediums in terms of carbon dioxide concentrations(rice straw: 320, ALC: 270 mg/l). The concentration of hydrogen sulfide was stable over the experimentation. The actual concentrations of hydrogen sulfide were 4, 3 and 3 ppm at the days of 7, 21 and 36, respectively. These results suggest that biofilter ducting systems may remove odors from pig house effectively.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.8
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• pp.1528-1535
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• 1994

In this paper, a filtered-X LMS algorithm by new error path identification method is proposed for active noise control system. The proposed algorithm identifies accurately the error path transfer function using three microphones and the control of error signal through double loop scheme with on-line. In the computer simulation using the sinusoidal and the practical duct noise, the proposed algorithm reduces noise level about 29.1dB and 10.4dB, respectively. We can observe the improvement of about 0.5dB and 2.5dB in noise level compared with that obtained using the filtered-X LMS algorithm of Eriksson model.

• The Korean Journal of Malacology
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• v.12 no.2
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• pp.109-121
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• 1996

Histochemical experiment was carry out respectively to confirm the properties of the salis (Achatina fulica and Incilaria fruhstorferi). SDS-PAGE was carried out to compare and invertigate the distribution aspects of protein patterns between the two species. Five types(A, B, F, H and I)of gland cells with four neutral mucopolysaccharide cells and one acid mucopolysaccharide cells and one acid mucopolysaccharide cell were observed in acinous of Achatina fulica, while six types were observed in acinous of Incilaria fruhstorferi: ond acid mucopolysaccharide cell(type-A) and four neutral mucopolysaccharide cells(type-B, C, D and F) and one cell that acid mucopolysaccharide is only mimbrane that surrounded granule(type-E). The results are follows:The thpe-A fland cell is commonly observed between the two species. The type-A gland cell in Achatina fulica possesses a nucleus with a developed heterdchromatin, and the cytoplasm was filled with round granules. The granules were surrounded with an uncertain boundary mimbrane and confirmed with neutral mucopolysaccharides, but is confirmed acid mucopolysaccharide in Incilaria fruhstorferi.The type-B gland cell is obwerved in the two species, too. The type-B gland cell in Achatina fulica was round shaped, and included an evenly alrge nucleus. The uncleoplasm included granules that were confirmed in the neutral mucopolysaccharides of the two species. The type-C and D gland cells exist only in Incilaria fruhstorferi, nucleoplasm was well developed heterochromatins. The type-E gland cell appears in the acinous surrounded the salivary gland of Incilaria fruhstorferi. Thdse granules appear irregular irregular shape and size and the cytoplasm is formed in alveolar. The type-F gland cells are commonly observed in the salivary glands of the two species. They are similar with the type-B gland cell, but the granular shape is comparatively small and irregular, and possess the neutral mucos granules. The type-H gland cells are mainly seen in only Achatina, and in nucleus is a well developed heterochromatin. The cytoplasm is filled with round small granules with acid mucopolysaccharide for alcianophilia observed. The type-I cell was small cell with an irregular shape and only observed in the gland cells of Achatina fulica. The heterochromatins were developed in the nucleus and the granules are not observed in cytoplasm.Secretory ducts of saliva are composed of the interlobular duct and interlobar secretory duct. In Achatina fulica the interlobular duct consists of a simple cuboidal epithelium, while the endothelium of intralobar secretory duct of Incilaria fruhstorferi consists of a simple squamous epithelium and in the cytoplasm is filled with granules(type-G secretory cell). A SDS-PAGE was carried out to confirm that the protein band pattern consist of salivary gland. In conclusions, five more bands in Achatina fulica and three bands in Incilaria fruhstorferi were confirmed in MW<29 kDa. one main band coincides comparatively with both and is between 29-45 kDa. There are four main bands in Achatina fulica and two main bands in Incilaria fruhstorferi between 45-66.5 kDa respectively. The bands in Achatina fulica seem more complex than in incilaria fruhstorferi.

• Journal of Surface Science and Engineering
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• v.46 no.3
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• pp.133-138
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• 2013

We have developed a 2D axi-symmetric numerical model for an inductively coupled plasma system in order to analyze gas mixing effect through a narrow gap shower head. For frictional flow, holes of 0.5 mm diameter and 2 mm length are approximately modeled in 2D. Gas velocity distribution 10 mm below the shower head showed 2 times difference between the center and the edge at 10 mTorr. At 10 mm above the wafer, it was increased to 6 times difference due to the pumping duct effect. The model with a 5 mm height buffer region of a shower head showed reasonable behavior of Ar discharge. The density of Ar metastable showed additional peak inside the buffer region around the edge holes.

• Journal of Ocean Engineering and Technology
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• v.26 no.6
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• pp.53-58
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• 2012

An experimental study on the hydrodynamic performance of a backward bent duct buoy (BBDB) was performed in a 2D wave tank. The BBDB is one of the promising oscillating water column (OWC) types of floating wave energy converters. Two different corner-shaped BBDBs (sharp-corner and round-corner) were used to measure the maximum chamber surface elevations and body motions for various incident wave conditions, and their hydrodynamic characteristics were compared. In order to investigate the effect of the pneumatic pressure inside the chamber, the heave and pitch angle interacted with elevations were compared for both open chamber and partially open chamber BBDBs. From the comparison study, the deviation in the chamber surface elevations between the two shapes of BBDBs was found to be significant near the resonance period, which may be explained by viscous energy loss. It was also found that the pneumatic pressure noticeably affected the chamber surface elevation and body motions.

• Journal of Animal Environmental Science
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• v.17 no.sup
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• pp.43-50
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• 2011

This study was conducted to verify the effect of chlorine dioxide ($ClO_2$) on odor reduction at a commercial swine facility consisting of a windowless piglet barn and a grower/fattening barn. The windowless piglet barn used a duct ventilation system. Air velocity at very below the upper duct was 4.53 m/s. Air velocity at the lower space around the living space of pigs in the grower/fattening barn was 0.26 m/s. $NH_3$ concentration was around 9ppm and less than 3 ppm before and after the $ClO_2$ spraying, respectively, which was over 70% reduction. There was no $H_2S$ detection. $NH_3$ concentrations measured in the windowless grower/fattening barn and at the exhausted air were 26 ppm and 11ppm, respectively. $NH_3$ concentration at a biocurtain outside was less than 1 ppm. Hence, $ClO_2$ spraying at windowless barns was effectively decreased malodor such as $NH_3$.

• Journal of the Korean Society of Radiology
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• v.15 no.7
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• pp.983-989
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• 2021

In this study, we intend to evaluate image quality and provide to clinical basic data by applying to 2D TSE (RT) and 3D GRASE (BH) techniques using Fast MRCP testing methods for application to patients in poor patient condition. Data were analyzed for 30 patients (15 males, 15 females, and 64±4.26 average age) who underwent MRCP tests. The equipment used was Ingenia CX 3.0 T equipment and Ds anterior coil was used for data acquisition. SNR and CNR of each image were measured through quantitative analysis, and the quality of the image was evaluated by dividing it into 5 grades for qualitative evaluation. The image evaluation was performed on the paired t-test and the Wilcoxon test, and when the p value was 0.05 or less, it was considered to be significant. As a result of quantitative analysis of SNR and CNR, 3D GRASE (BH) was measured high when comparing the two techniques, 2D TSE (RT) MRCP and 3D GRASE (BH) (p<0.05). The qualitative analysis result is a sharpness of the bile duct: 3D GRASE(BH): 4.12±0.03, Overall image quality: 3D GRASE(BH): 4.21±0.91 was high (p=0.001). The motion artifact of the bile duct showed no significant difference with two techniques(2D TSE(RT): 4.41±0.04, 3D GRASE(BH): 4.53±0.14(p=0.067). However, the background suppression obtained significant results with 2D TSE(RT) of 4.14±0.55(p=0.001). In conclusion, as a result of using the Fast MRCP testing method, MRCP images obtained by 3D GRASE (BH) had an advantage over MRCP images using 2D TSE (RT). However, there will be useful results of 2D TSE(RT) MRCP technique in patients who have difficulty holding their breath.