• Membrane Journal
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• v.21 no.4
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• pp.360-366
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• 2011

The effect of cross-flow velocity and transmembrane pressure (TMP) on membrane fouling was observed from pilot-scale operation of thermophilic anaerobic membrane bioreactor (AnMBR) treating food waste leachate. It was found that fouling rate was reduced significantly as cross-flow velocity increased at constant TMP mode of operation while this effectiveness was more pronounced at lower TMP. Higher TMP resulted in less permeable fouling layer possibly due to compressibility of foulant material on membrane surface. Particle sizes of membrane concentrate ranged from 10 to $100{\mu}m$, implying that shear-induced diffusion enhance back transport of these particle sizes away from the membrane effectively. From the continuous operation of AnMBR, it was confirmed that shear rate played an important role in the reduction of membrane fouling. Membrane autopsy works at the end of operation of AnMBR showed clearly that both organic and inorganic fouling were significant on membrane surface. Surface shear by cross-flow velocity was expected to be less effective to remove irreversible fouling which can be mainly caused by the adsorption of organic colloidal materials into membrane pores.

• Journal of Digital Convergence
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• v.10 no.8
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• pp.21-28
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• 2012

The study aims to explore industrial and firms' strategic factors affecting diffusion of digital convergence by studying major global IPTV markets. Market and firm variables are selected using the Industrial Organization's SCP approach. Data for the variables are collected from global 31 IPTV operators representing 20 countries. The analysis indicates that the penetration of broadband Internet and the market share of a dominant player in the Pay TV positively affect the penetration of the IPTV service, whereas the penetration of Pay TV, ARPU, firms' strategy and resource do not have influence on its penetration. The study is the cross-country analysis and contributes to the media study by exploring the relationship between market variables and the development of convergent media. Consequently, the study is expected to help policy makers tailor their digital policy for local environment.

• Economic and Environmental Geology
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• v.17 no.4
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• pp.299-314
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• 1984

The Yeongdo Island in Busan City is a remnant of the latest Cretaceous volcano, and consists geologically of andesites, rhyolite tuff, pelitic and psammitic hornfelses, lapilli rhyodacite tuff of the Yucheon Group, felsite and felsite porphyry of the Bulgugsa intrusives, and Holocene sediments in ascending order. The hornfelses are bound to the Taejongdae Formation. The stratigraphic position of the Formation is determined definitely into the Yucheon Group, thus the geologic age is approximately the same with the volcanic rocks of the Group. The sediments had been thermally metamorphosed to make pelitic and psammitic hornfelses of the albite epidote hornfels facies by the effects of active hydrothermal circulation, vaporization, and hybridization of andesitic solution, or of basification of acidic intrusives. Thus, on occasion, those hornfelses are not used to be distinguished from the andesitic rocks in the southeastern part of the Korean peninsula. The paleocurrent direction determined from several cross-beddings of the Taejongdae Formation is suggested to be from southwest to northeast. Orbicular rocks occur in hornfelsed rhyolite tuff, pelitic- and psammitic-hornfelses, and felsite porphyry at a lot of outcrops in the area of southwestern shoreline of the Yeongdo Island. Orbicules in rhyolite tuff and hornfels in the island might have originated from diffusion processes of metasomatic metamorphism carried out by hydrothermal solution rised from the intrusive adamellite which may be emplaced deeply under the Yeongdo volcanics. Those orbicules are due to metasomatic, secondary, and epigenetic origin. Proto-, multi-shelled, and multi-cored orbicules are described in the orbicular tuff. But multi-cored orbicules are not found in the orbicular fornfels. 250 tuff-orbicules numbered sporadically are in $20,000m^2$ area of the locality of orbicular tuff. About 60 hornfels-orbicules occurred sporadically are in $1,700m^2$ area of the locality of orbicular hornfels in the Taejongdae Formation. Orbicules in felsite porphyry might have originated by diffusion reaction between xenoliths and a quiescent zone in felsite porphyry magma. Those are of igneous, primary, and syngenetic origin.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.36D no.4
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• pp.48-56
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• 1999

In this paper, we have investigated experimentally the effects of initial oxygen concentration on oxygen pileup phenomenon and the diffusion of implanted impurities. 1.2 MeV $^{11}B^{+}$ and 2.2 MeV $^{31}P^{+}$ ions were implanted into p-type (100) Si wafers with a dose of 1${\times}10^{15}$ / $\textrm{cm}^2$. Secondary ion mass spectrometry(SIMS) measurements were carried out to obtain depth distribution profiles for implanted impurities and oxygen atoms after two-step annealing of $700^{\circ}C$(20 hours)+$1000^{\circ}C$(10 hours). Residual secondary defect distribution and annealing behabiour were also studied by cross-sectional transmission electron microscopy(TEM) observations. Oxygen pileup nearly $R_p$(projected range) were observed by SIMS measurements and considerable amount of residual secondary defect layer were observed by TEM observations. It can be seen that oxygen atoms are trapped at the secondary defects by the experimental results. Enhanced diffusions of boron and phosphorus to the bulk direction were observed with the increasing of initial oxygen concentration.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.11a
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• pp.198-201
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• 2002

In this paper, the dependence of Ni-silicide properties such as sheet resistance and cross-sectional profile on the dopants have been characterized. There was little dependence of sheet resistance on the used dopants such as As, P, $BF_{2}$ and $B_{11}$ just after RTP (Rapid Thermal Process). However, the silicide properties showed strong dependence on the dopants when thermal treatment was applied after formation of Ni-silicide. $BF_{2}$ implanted sample shows the best stable property, while $B_{11}$ implanted one was thermally unstable. The main reason of the excellent property of $BF_{2}$ sample is believed to be the retardation of Ni diffusion by the flourine.

• Journal of Pharmaceutical Investigation
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• v.19 no.2
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• pp.93-98
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• 1989

The study was performed to compare the dissolution, diffusion and absorption characteristics using Sartorius dissolution and absorption simulator and in vivo bioavailability of commercially available rifampicin capsules. Both brands C and F showed similar dissolution patterns and absorption properties through artificial gastric barrier in Sartorius simulator. Diffusion rate constants through the membrane of brands C and F were $3.04\;{\times}40^{-3}$ and $2.88\;{\times}\;10^{-3}cm/min$, respectively. Rifampicin capsules were administered orally to six fasted healthy volunteers according to cross-over design. The pharmacokinetic parameters between brands C and F, maximum plasma drug concentration$(C_{max})$, the time to reach $C_{max}$, absorption rate constant and area under the curve $(AUC_{0-24hr})$, elimination rate constant, and amount of drug excreted in urine were 6.11 and $7.27\;{\mu}g/ml$, 2.71 and 1.52 hr, 0.6371 and $1.6456 hr^{-1}$, 57.84 and $57.28\;{\mu}g\;{\cdot}\;hr/ml$, 0.1891 and $0.1734 hr^{-l}$, 119.98 and 119.93 mg, respectively. On the basis of experimental results, it was concluded that the bioavailability of brand C rifampicin capsules was almost the same as that of brand F rifampicin capsules.

• Membrane Journal
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• v.11 no.3
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• pp.124-132
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• 2001

Silica membranes were prepared on a porous ${\alpha}$-alumina tube with pore size of 150nm by sol-gel and chemical vapor deposition(CVD) method for hydrogen separation at high temperatures. Silica and ${\gamma}$-lumina membranes formed by the sol-gel method possessed a large amount of mesopores of a Knudsen diffusion regime. In order to improve the $H_2$ selectivity, silica was deposited in the sol-gel derived silica/${\gamma}$-alumina layer by thermal decomposition of tetraethyl orthosilicate(TEOS) at $600^{\circ}C$. The CVD with forced cross flow through the porous wall of the support was very effective in plugging mesopores that were left unplugged in the membranes. The CVD modified silica/alumina composite membrane completely rejected nitrogen permeation and thus showed a high $H_2$ selectivity by molecular sieve effect. the permeation of hydrogen was explained by activated diffusion and the activation energy was 9.52kJ/mol.

• Korean Journal of Materials Research
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• v.1 no.2
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• pp.99-104
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• 1991

Trantalum thin films have been prepared by DC sputtering onto As, P, and $BF_2$-implanted ($5{\times}10^15cm^-2$) poly-silicon. The heat treatments by rapid thermal annealing(RTA) have been applied to these samples for the formation of silicides. We have studied the application possibility of Ta-silicide as gate electrode and bit line. The silicide formation and the dopant diffusion after the heat treatment were investigated by various methods, such as four-point probe, X-ray, SEM cross sectional views, ${\alpha}$-step, and SIMS, The tantalum disilicide($TaSi_2$) are formed in the temperature above $800^{\circ}C$, and grown in colummar structure. $TaSi_2$ has a good surface roughness, having range from $80{\AA}\;to\;120{\AA}$, and implanted dopants are incoporated into the $TaSi_2$ layer during the RTA temperature.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2001.11a
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• pp.29-30
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• 2001

This paper presents some results of plasma nitriding on hard chromium deposit. The substrates were C45 steel and $30~50{\;}\mu\textrm{m}$ of chromium deposit by electroplating was formed. Plasma nitriding was carried out in a plasma nitriding system with $95NH_3{\;}+{\;}SCH_4$ atmosphere at the pressure about 600 Pa and different temperature from $450^{\circ}C{\;}to{\;}720^{\circ}C$ for various time. Optical microscopy and X-ray diffraction were used to evaluate the characteristics of surface nitride layer formed by nitrogen diffusion from plasma atmosphere inward iCr coating and interface carbide layer formed by carbon diffusion from substrate outward Cr coating. The microhardness was measured using microhareness tester at the load of 100 gf. Corrosion resistance was evaluated using the potentiodynamic measurement in 3.5% NaG solution. A saturated calomel electrode (SiCE) was used as the reference electrode. Fig.1 shows the typical microstructures of top surface and cross-section for nitrided and unnitrided samples. Aaer plasma nitriding a sandwich structure was formed consisting of surface nitride layer, center chromium layer and interface carbide layer. The thickness of nitride and carbide layers was increased with the increase of processing temperature and time. Hardness reached about 1000Hv after nitriding while 900Hv for unnitrided hard chromium deposit. X-ray diffraction indicated that surface nitrided layer was a mixture of $Cr_2N$ and CrN at low temperature and erN at high temperature (Fig.2). Anodic polarization curves showed that plasma nitriding can greatly improve the corrosion resistance of chromium e1ectrodeposit. After plasma nitriding, the corrosion potential moved to noble direction and passive current density was lower by 1 to 4 orders of magnitude compared with chromium deposit(Fig.3).

• Journal of the Korean institute of surface engineering
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• v.52 no.6
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• pp.316-320
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• 2019

The effect of boronizing on mechanical properties including wear behavior and hardness of Inconel 625 superalloy were investigated. The cross-section observation demonstrated that boronized samples were composed of multi-phase boride layer (Cr_xB_x, Ni₂B), diffusion layer, and substrate. The boride and diffusion layers were increased with increasing treatment temperature and holding time. However, Cr_xB_x layer was partially peeled off when it treated 1000℃. Subsequently, boride layer was completely separated from substrate with increasing temperature and time. A partial peeling of Cr_xB_x layer is not noticeably degraded mechanical properties. In particular, friction coefficient and wear resistance were enhanced in lack of Cr_xB_x phase. Therefore, these results suggest that a Ni₂B phase mainly contribute to wear behavior on boronized Inconel 625 superalloy.