• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.11a
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• pp.120-124
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• 2004

본 연구는 Diluted Ceria 입자를 사용한 $SiO_2$(Oxide) CMP 현상에 대한 내용이다. Ceria Slurry의 경우 Silica Slurry와 비교하였을 때 Oxide Wafer 표면과 축합 화학반응을 일으키며 Chemistry Dominant한 CMP Mechanism을 따르고, Wafer Center Removal Rate(RR) Fast 의 특성을 가진다. Ceria Slurry의 문제점인 연마 불균일도를 해결하기 위해 Tribological System을 이용하였다. CMP Tribology는 Pad-Slurry 유막-Wafer의 System을 가지며 윤활막에 작용하는 마찰계수(COF)가 주요 인자이다. Tribology에 적용되는 Stribeck Curve를 통해 Slurry 윤활막의 두께(h) 정도를 예상할 수 있으며, 이 윤활막의 두께를 조절함으로써 Uniformity 향상이 가능하다. 이 Ceria Slurry CMP의 연마 불균일도를 향상시킬 수 있는 방법으로 pH 조절 및 점도 증가가 있다. Ceria 입자 CMP는 분산액의 pH 변화에 강한 작용을 받게 되며 PH5 근방에서 최적화된 Uniformity가 가능하다. 점도를 증가시키는 경우 유막 h가 증가하게 되어 Ceria Slurry의 유동이 균일 분포 상태에 가까워지며 Wafer Uniformity 향상이 가능하다.

• Journal of Environmental Science International
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• v.20 no.2
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• pp.215-222
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• 2011

The adsorption behavior of nitrate nitrogen was investigated from aqueous solution using char prepared from oak chip. The removal rate of nitrate nitrogen was found to be dependent on temperature and it is increased as the temperature increase. Adsorption equilibrium data of nitrate nitrogen on oak char. reasonably fitted Langmuir and Freundlich isotherm models. The adsorption energy obtained from D-R model was 12.5 kJ/mole at $20^{\circ}C$ indicating an ion exchange process as primary adsorption mechanism. Thermodynamic parameters such as ${\Delta}G^o$, ${\Delta}H^o$, and ${\Delta}S^o$ were -23.76 kJ/mole, 26.1 kJ/mole and 89.7 J/K mole at $20^{\circ}C$, respectively, indicated that the nature of nitrate nitrogen adsorption is spontaneous and endothermic.

• Journal of Physiology & Pathology in Korean Medicine
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• v.23 no.2
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• pp.389-396
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• 2009

The ethanol extract of Persicaria perfoliata (EPP) induced relaxation of the phenylephrine-precontracted aorta in a dose-dependent manner, which was abolished by removal of functional endothelium. Pretreatment of the aortic tissues with NG-nitro-L-arginine methyl ester (L-NAME) or 1H-[1,2,4}-oxadiazole-[4,3-${\alpha}$)-quinixalin-1-one (ODQ) inhibited the relaxation induced by EPP. However, EPP-induced relaxation was not blocked by pretreatment with indomethacine, glibenclamide, tetraethylammonium (TEA), atropine, or propranolol. Incubation of endothelium-intact thoracic aortic ring with EPP increased the production of cGMP, which was also blocked by pretreatment with L-NAME or ODQ. These results suggest that EPP dilates vascular smooth muscle via endothelium-dependent NO/cGMP signaling.

• Proceedings of the KSME Conference
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• 2002.08a
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• pp.313-316
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• 2002

A grease filter is used to remove grease generated from a cooking appliance in a kitchen. This numerical study has been conducted to investigate the particle collection characteristics of a grease filter having nominal flowrate of $100m^{3}/h$. The flow field and particle trajectories in the grease filter with a flow chamber were simulated by using the commercial code of STAR-CD. The pressure drop of a grease filter rapidly increases with increasing the air flowrate. The numerical values of the pressure drop are slightly lower than the experimental values when the air flowrates are 50, 75, and $100m^{3}/h$. The particle collection efficiency of a grease filter increases with increasing the particle diameter and the air flowrate, which means that the inertial impaction is a dominant particle removal mechanism in a grease filter The cut-off diameter of the tested grease filter representing $50-{\%}$ collection efficiency is about $11.6{\mu}m$ for water droplets at $100m^{3}/h$.

• Journal of Advanced Marine Engineering and Technology
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• v.10 no.2
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• pp.136-145
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• 1986

The perfect and accurate methods to control the wear are not made clear so far. For this phenomenon only mating surface has been studied. In order to control the wear the essence of it has to be made clear. It is reported that adhesive wear might occure as a result of plastic deformation, the fracture and removal or transfer asperities on close contacting surfaces. On this view point the plastic flow was attempted to compare with fluid or electromagnetic flow. The partial differential equations of equilibrium for the plane strain deformation will make use of the method of characteristics. The characteristic curves or characteristics of the hyperbolic equation coincide with the slip lines by R. Hill's papers. By Hencky's stress equation, it is evident that if P and .phi. are prescribed for a boundary condition then it may be possible to proceed along constant .alpha. and .betha. lines to determine the value of the hydrostatic pressure everywhere in the slip line field net work. A wedge formation mechanism has been considered for an explanation of this matters. The analysis shows that there is a critical value, which depends on the hardness ratio and the shear stress on the interface, for the top angle of asperity is less than this critical value, the asperity can yield plastically despite of being harder than the mating surface.

• Journal of the Korean Chemical Society
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• v.61 no.5
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• pp.231-237
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• 2017

Efficiently removing Al(III) from rare earth is very significant because even trace amount of Al(III) can cause serious harm to the rare earth materials. In this paper, a nitrogen-containing activated carbon, AC-P700, was synthesized using peas as raw materials. The AC-P700 was characterized by surface area analyzer, FT-IR, and XPS methods. The adsorption and recognition properties of AC-P700 towards Al(III) were investigated, and the recognition mechanism was also analyzed. The BET special surface area of AC-P700 was $1277.1m^2{\cdot}g^{-1}$, and the average pore diameter was 1.90 nm. The AC-P700 possesses strong adsorption affinity and excellent recognition selectivity towards Al(III). The adsorption capacity for Al(III) could reach to $0.53mmol{\cdot}g^{-1}$, and relative selectivity coefficients relative to La(III) and Ce(III) is 9.6 and 8.7, respectively. Besides, AC-P700 possesses better regeneration ability and reusability.

• Animal cells and systems
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• v.2 no.4
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• pp.513-520
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• 1998

Though the wandering spiders do not produce webs for prey-catching, they have silk producing apparatus. Among the four kinds of silk glands in the wolf spider, Pardosa astrigera, the ampullate one is the most predominant gland in both sexes, and is composed of three functional parts; excretory duct, storage ampulla and convoluted tail regions. The duct is basically composed of three superposed types of layers which are inner cuticles, monolayered epithelial cells and peripheral connective cells. The electron lucent subcuticles which have the functions of water removal and orientation of silk fibers during polymerization are well developed at the anterior region near the spinneret. Whereas the endocuticles which contain two types of banding patterns at the cross section are developed at the rest of the duct region. The secretory silks are synthesized within the glandular epithelial cells of the tail as secretory granules, and then released to the inner cavity of the storage ampulla by the mechanism of apocrine secretion. Most of these secretory vesicles are originated from the rough endoplasmic reticula of the glandular epithelial cells, whereas no Golgi complexes are found in any of the cells which have been examined.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.09a
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• pp.330-333
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• 2003

Recently electrokinetic process is known to be a promising remediation technology for the contaminated soils with heavy metals, radionuclides, organic matters, and so on. The contaminants in electrokinetic technology are removed mainly by three mechanisms; electroosmosis, electromigration, and electrophoresis. When direct current is introduced between two electrodes planted in soil, a large amount of hydrogen ions is formed and moves from anode to cathode with the other cations contained in electrolyte. The water flow caused by tile movement of cations is called as electroosmosis. Especially for non-ionic pollutants, the electroosmotic flow(EOF) is the most important removal mechanism among them and transports contaminants from anode to cathode along the water flow. In this study, characteristics of electroosmotic flow was investigated according to the resistance state of soil. The decrease, maintenance, and increase of soil resistance could be obtained by controlling ions in soil. When the resistance of soil was decreasing or maintained, the EOF is proportional to electric current and voltage, respectively and when the resistance was increasing, the EOF is proportional to only electric current not voltage.

• JSTS:Journal of Semiconductor Technology and Science
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• v.16 no.6
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• pp.825-831
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• 2016

In this paper, a transimpedance amplifier based on a new DC offset cancellation (DCOC) method is proposed for WCDMA/LTE applications. The proposed method applies a sample and hold mechanism to the conventional DCOC method with a DC feedback loop. It prevents the removal of information around the DC, so it avoids signal-to-noise ratio degradation. It also reduces area and power consumption. It was designed in a $0.13{\mu}m$ deep n-well CMOS technology and drew a maximum current of 1.58 mA from a 1.2 V supply voltage. It showed a transimpedance gain of $80dB{\Omega}$, an input-referred noise current lower than 0.9 pA/${\surd}$Hz, an out-of-band input-referred 3rd-order intercept point more than 9.5 dBm, and an output DC offset lower than 10 mV. Its area is $0.46mm{\times}0.48mm$.

• Membrane and Water Treatment
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• v.8 no.1
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• pp.73-88
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• 2017

Adsorption kinetics of aqueous ferric ion ($Fe^{3+}$) onto bio-natural rice grains (BRG) have been studied in a batch system. The influence of contact time (0-180 minutes), the dosage of BRG adsorbent (10, 20, 40, and $60gL^{-1}$), and ambient temperature (27, 37, 47, and $57^{\circ}C$) for the adsorption system have been reported. The equilibrium time achieved after 20 minutes of adsorption contact time. The maximum removal of ferric ion is 99% by using $60gL^{-1}$ of BRG, $T=37^{\circ}C$, and $50mgL^{-1}$ ferric ion solution. Adsorption kinetic and diffusion models, such as pseudo-first order, pseudo-second order, and Weber-Morris intra-particle diffusion model, have been used to describe the adsorption rate and mechanism of the ferric ion onto BRG surface. The sorption data results are fitted by Lagergren pseudo-second order model ($R^2=1.0$). The kinetic parameters, rate constant, and sorption capacities have been calculated. The new information in this study suggests that BRG could adsorb ferric ion from water physiosorption during the first 5 minutes. Afterward, the electrostatic interaction between ferric ion and BGR-surface could take place as a very weak chemisorptions process. Thus, there is no significant change could be noticed in the FTIR spectra after adsorption. I recommend producing BGR as a bio-natural filtering material for removing the ferric ion from water.