• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.960-965
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• 2014

Transmission loss of specimen is calculated by measuring energy of incident and transmission and using reverberant room of large size. But normal measurement of transmission loss has trouble because it is actually demanded that large area and specimen of certain size is satisfied with condition of diffused sound field. Especially, in case of mechanical component, interested frequency band is mid-frequency band between 500 ~ 2k Hz, and it is used to be available to minimize a reverberation chamber under conditions satisfying acoustic one because production of specimen for transmission loss measurement has limit. But, as in semi-reverberation room, it is difficult to satisfy condition of diffuse sound field and modification factor is applied to complement that. Correction factor when measuring transmission loss using semi-reverberation chamber is required accuracy because it works as main factor determining reliability of reuslts on transmission loss. In this study, it is analyzed that an effect on correction factor based on varying materials and sizes of specimens in order to deduction of it. Also It is confirmed that applied by elicited correction factor with actual railway vehicle's floor has reliability.

• Bulletin of the Korean Chemical Society
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• v.31 no.6
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• pp.1638-1642
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• 2010

Mesoporous carbon CMK-3s with different textural properties have been used for the adsorption of phenol to understand the necessary physicochemical properties of carbon for the efficient removal of phenol from contaminated water. The kinetic constants (both pseudo-second order and pseudo-first-order kinetics) increase with increasing pore size of carbons. The maximum adsorption capacities correlate well with micropore volume compared with surface area or total pore volume even though large pore (meso or macropore) may contribute partly to the adsorption. The pore occupancies also explain the importance of micropore for the phenol adsorption. For efficient removal of phenol, carbon adsorbents should have large micropore volume and wide pore size for high uptake and rapid adsorption, respectively.

• Transactions of the Korean hydrogen and new energy society
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• v.24 no.1
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• pp.84-90
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• 2013

The hydrogen or oxygen gas producted by electrolysis become many bubbles in the electrolyte, but exact data on the behavior of these bubbles in the separator of an electrolysis stack didn't become known. In this study, the flow visualization experiment on the behavior of bubbles in the flow pattern of the array type separator is performed by using of a visible alkaline electrolysis stack and a stereoscopic microscope. As the results, a fine size bubbles adhered to the surface of the flow pattern grow to large sized bubbles until each bubble's buoyance is lager than the sum of external force and weight. And then the large bubbles flow into the upper area of the separator. Bubbles adhered to the surface of the vertical flow pattern grow quickly than them adhered to the surface of the horizontal flow pattern. Also, he electrolysis efficiency is declined because many multi-size bubbles occupied the wide volume in the flow pattern.

• Journal of Korean Society on Water Environment
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• v.22 no.3
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• pp.468-474
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• 2006

In the secondary settling tanks, three different types of settling phenomena occurs; i.e., zone settling for sludge thickening in the bottom part of settling tank, and discrete and flocculent settling for clarification in the upper part. In this paper, morphological parameters of the floc in sludge blanket layers along the length of a long rectangular tank were investigated. The plant used for this study had a serious bulking problem caused by Microthrix parvicella. Floc size decreased as the surface area of settling tank increases, which indicates that in the secondary settling tank where zone settling believed to be predominant, free or flocculent type of settling contributes to floc size distributions. Large floc particles deposit in the front zone of settling tank, but small and loose flocs mostly in the zone near its outlet. On the other hand, filament length contained in one gram of sludge blanket solid increases along the flow direction. Large flocs with less filaments settle faster, but small flocs having more filaments result in poor settling. These results support function of microorganism selection occurring in secondary settling tank. In addition, designing a long rectangluar settling tank with double hoppers might be one of the ways of bulking control, but this idea has to be verified with a further study.

• Proceedings of the Korean Information Science Society Conference
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• 2010.06c
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• pp.447-451
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• 2010

In this paper, we propose a simple but effective algorithm to increase the speed of Emphysema region classification. Emphysema region classification method based on CT image consumes a lot of time because of the large number of subregions due to the large size of CT image. Some of the sub-regions contain no Emphysema and the classification of these regions is worthless. To speed up the classification process, we create an algorithm to select Emphysema region candidates and only use these candidates in the Emphysema region classification instead of all of the sub-regions. First, the lung region is detected. Then we threshold the lung region and only select the dark pixels because Emphysema only appeared in the dark area of the CT image. Then the thresholded pixels are clustered into a region that called the Emphysema pre-detected region or Emphysema region candidate. This region is then divided into sub-region for the Emphysema region classification. The experimental result shows that Emphysema region classification using predetected Emphysema region decreases the size of lung region which will result in about 84.51% of time reduction in Emphysema region classification.

• Journal of the Korean Society for Heat Treatment
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• v.33 no.1
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• pp.20-24
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• 2020

Single crystal diamonds are in great demand in such fields as mechanical, electronic applications and optoelectronics. Large area single crystal diamonds are attracting attention in future industries for mass production and low cost. In this study, hot filament CVD (HFCVD) is used to grow large area single crystal diamond. However, the growth rate of large area single crystal diamond using HFCVD is known to be very low. The goal of this study is to use single crystal diamond substrates in HFCVD with methane-hydrogen gas mixtures to increase the growth rate of single crystal diamond and to optimize the conditions by analysing the effects of deposition conditions for high quality crystallinity. The deposition pressure, the ratio of CH₄/H₂ gas, the substrate temperature and the distance between the filament and the substrate were optimized. The sample used a 4×4 (mm²) size single crystal diamond substrate (100), the CH₄/H₂ gas ratio was fixed at 5%, the substrate temperature was synthesized to about 1000℃. At this time, the deposition pressure was changed to three types of 50, 75, 85 Torr and deposited. Finally, optimization was investigated under pressure conditions to analyse the growth rate and quality of single crystal diamond.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.14 no.1_2
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• pp.105-116
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• 1992

Latissimus dorsi myocutaneous flap is useful for the breast reconstruction, chest wall coverage, free flap transfer, and head and neck area reconstruction, especially in large defect. We have had some experience of 5-pedicled and 1-free latissimus dorsi myocutaneous flap in head and neck area and found many advantages and some problems. The conclusions were as follows : 1. Potentially large flap size enabled us agressive tumor resection and reconstruction. 2. Speedy and easy flap elevation and long vascular pedicles reduced operation time and flap failure. 3. Due to fewer complication and functional loss of doner site, pedicled latissimus dorsi flap was a good choice for large head and neck reconstruction. 4. Because of flap bulkness, thin and small defect was not appropriate for reconstruction.

• Journal of Korean Society of Rural Planning
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• v.16 no.3
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• pp.87-101
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• 2010

This research has a significance on providing basic material of landscape ecological planning and open space planning of the future site by selecting Sinseo innovative city area, large residential land development district in rural area, by classifying biotope types and implementing recreational value assessment in the level of area. First of all, as a result of classification of biotope types in research site, total 11 biotope type groups including stream biotope and its subordinate 51 biotope types. Also, as a result of the first value assessment of classified biotopes, there are total 5 types such as vegetation-full natural river, fallow ground in I grade. In addition, it is analyzed that grade II have 18 types, III are 10, IV are 12, the least valuable V are 6. Especially, grassland biotope(GD) was classified into grade II, which is one grade raised, because it is analyzed that it has high value in terms of normal access and availability although it was assessed as grade ill in terms of natural experience quality. Lastly, as a result of the second assessment, special areas for natural experience and recreation(1a, 1b) are 15, areas for natural experience and recreation(2a, 2b, 2c) are 47. Especially, the 52th drawing mark space was grade II in the first assessment but its value grade was upgraded because of its high value in terms of use evidence, size of the area, accessibility with housing area, history and cultural character and so on.

• Journal of Wetlands Research
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• v.13 no.3
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• pp.523-534
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• 2011

In this study, the particle size distribution and pollutants content of sediments collected from different sites in the coastal area of Chungnam province were analyzed. The sediment samples were collected from different parking lots near beaches, harbors, museum and bridges. The particle size distribution analysis showed that the particle is generally $106-500{\mu}m$ and the effective size $D_{10}$ ranges from 40 to $60{\mu}m$ while the $D_{50}$ and $D_{60}$ ranges from 200 to $810{\mu}m$ and 235 to $1005{\mu}m$, respectively. For particle size $D_{10}$, there was no significant difference in all sites. However, for $D_{50}$ and $D_{60}$, the range is large. Sediment analysis implicates that as the particle size decreases, the pollutant content increases. This is because smaller particles have higher specific surface area resulting to have more adsorption capacity. Particles from tires, emission gas from vehicles and dust particles belongs to smaller particles. For particle sizes less than $63{\mu}m$, the analysis showed that as the particles become coarser, the concentration of VS, $COD_{cr}$, TN, and TP is at least 2 to 14 times higher. Cu and Pb were detected in all sites and shows a higher concentration with smaller particle size. Cu concentration are almost the same for all sites but in the case of Pb, the sediments from Sinjindo has higher concentration of up to 2 to 3 times as compared to those collected from the other sites. In the Beach site as well as in the Seocheon Ocean Museum, Cd was contained only in fine particles. However, in Daechon Harbor and Sinjindo Bridge sites, Cd was detected in all the sediment particle size.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.360.1-360.1
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• 2016

Hydroxyapatite (Ca10(PO4)6(OH)2, HAP) particles have attracted a great deal of attention in biomedical fields due to their good biocompatibility, bioactivity and fairly broad applications as drug delivery, dental implant, bone cement, and etc. Thus, many researchers have made an effort to add new functionalities such as luminescence, drug delivery, and bone regeneration properties up to HAP powders by controlling their nanostructure as well as composition. In this research, the mesoporous strontium substituted HAP (Sr-HAP) microspheres were synthesized using a hydrothermal method. In this synthesis, aspartic acid monomers were utilized to form microsphere by controlling surface energy of HAP particles and Sr ions were substituted into Ca ion sites, which induced luminescence property in HAP powders. Moreover, the change in the amount of Sr substitution was found to influence the particle size, morphology, and concurrently surface area, which led to changing drug loading as well as drug release property. The amount of Sr influences the morphology, luminescent properties, particle size, surface area cell viability and drug loading property, which are investigated by SEM, TEM, XRD, FTIR, BET, XPS and in vitro test such as MTT assay and drug release test. In particular, the multifunctional Sr-HAP with molar ratios of 0.25 (Sr/(Ca+Sr)) possessed the strongest luminescent property as well as the superior drug loading and sustained release properties that were correspondent with large surface area and pore size. Our study indicates that the fabricated multifunctional Sr-HAP microspheres are quite useful for bone regeneration and drug delivery.