• Korean Journal of Materials Research
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• v.18 no.6
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• pp.334-338
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• 2008

The purpose of this study is to characterize various electrolytes on electrochemical mechanical planarization (ECMP). The ECMP system was modified from conventional CMP system to measure the potentiodynamic curve and removal rate of Cu. The potentiodynamic curves were measured in static and dynamic states in investigated electrolytes using a potentiostat for the evaluation of the polishing behavior on ECMP. KOH (alkaline) and $NaNO_3$ (salt) were selected as electrolytes which have high conductivity. In static and dynamic states, the corrosion potential decreased and the corrosion current increased as a function of the electrolyte concentration. But, the electrochemical reaction was prevented by mechanical polishing effect in the dynamic state. The static etch and removal rate were measured as functions of concentration and applied voltage. When $NaNO_3$ was used, the dissolution was much faster than that of KOH. It was concluded that the removal rate was strongly depended on electrochemical dissolution. The removal rate increased up to 350 nm/min in $NaNO_3$ based electrolyte.

• Resources Recycling
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• v.17 no.6
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• pp.68-78
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• 2008

Using a Pinus koraiensis and Pinus rigida which are normally being discarded in South Korea, optimal conditions of producing activated carbons have been studied to recycle as a higher value-added product. This study consists of two processes, the production process of charcoals from waste timbers by low temperature pyrolysis and the production process of activated carbons from the charcoals by chemical activation reaction. This paper deals with the production process of activated carbons from the charcoals by chemical activation reaction. As an alkali has been generally used as an activating agent, KOH and NaOH which react well with a carbon were used in this study. As a result of the experiments, it is confirmed that activated carbons made with KOH treatment had superior values in physicochemical properties to NaOH, showing that there was no remain of KOH at the surface of the charcoals while there was $3{\sim}4%$ of NaOH remaining after the experiments. Thus, it is concluded that KOH reacted more actively with a charcoal than NaOH. Moreover, it was also found that values in physicochemical properties when using a Pinus koraiensis are superior to the ones when using a Pinus rigida. The optimal mixing ratio of an activating agent to a charcoal was 400 wt.%. To improve the physicochemical properties, activated carbons were washed out by distilled water after neutralization with SM hydrochloric acid solution. When activated carbons were produced from a Pinus koraiensis in this optimal conditions, value of BET surface area was found to be approx. $2400\;m^2/g$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.528-528
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• 2007

Cu CMP widely has been using for the formation of multilevel metal interconnects by the Cu damascene process. And lower dielectric constant materials are required for the below 45nm technology node. As the dielectric constant of dielectric materials are smaller, the strength of dielectric materials become weaker. Therefore these materials are easily damaged by high down pressure during conventional CMP. Also, technical problems such as surface scratches, delamination, dishing and erosion are also occurred. In order to overcome these problems in CMP, the ECMP (electro-chemical mechanical planarization) has been introduced. In this process, abrasive free electrolyte, soft pad and low down force were used. The electrolyte is one of important factor to solve these problems. Also, additives are required to improve the removal rate, uniformity, surface roughness, defects, and so on. In this study, KOH and $NaNO_3$ based electrolytes were used for Cu ECMP and the electrochemical behavior was evaluated by the potentiostat. Also, the Cu surface was observed by SEM as a function of applied voltage and chemical concentration.

• Korean Journal of Plant Resources
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• v.14 no.2
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• pp.175-181
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• 2001

Dormancy of intact zoysiagrass seeds hinders its seed propagation in which presowing seed treatment must be done to overcome it. The study was done to remodel the presowing treatments of zoysiagrass seeds by determining the treatment effects of seedcoat softening, prechilling, drying and combined light treatment with them or during germination stage. Seedcoat softening with different chemicals (NaOH 20%, KOH 20%, $H_2SO_4\;8M, acetone 20%) and periods (10, 30, 60 min.), prechilling with different periods at 3$^{\circ}C$, and drying with 4 hours at 35$^{\circ}C$ was done. Light sources were also applied with 660 nm red LED light, commercial fluorescent and incandescent light and darkness. Germination test was done in alternative day and night temperature of 35 and 2$0^{\circ}C$ to check the daily germination rates. With seeds treated with NaOH 20% for 30 minutes, red and incandescent light showing similar responses inclined their germination rates compared to dark conditions. Drying resulted in its higher rate than non-drying but fluorescent light treatment forced during drying more enhanced the rate than red light. While mean germination rate considering all the seedcoat softening treatment periods was the greatest in $H_2SO_4$ in comparison with NaOH, KOH and acetone, NaOH treatment for 30 minutes showed the best rate among the all the treatment levels. In the conditions of sowing them to no-mulching field, presowing treatment procedure of zoysiagrass seeds was remodeled: the seedcoat softening treatment with NaOH 20% for 30 minutes was done, washed, and chilled at 3$^{\circ}C$ for 2 weeks before dried under 4 hour fluorescent light illumination at 35$^{\circ}C$.

• Journal of Korean Society of Environmental Engineers
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• v.33 no.1
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• pp.39-46
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• 2011

NO oxidation is an important prerequisite step to assist the selective catalytic reduction (SCR) at low temperatures ($<200^{\circ}C$). Therefore, we conducted the lab- and bench-scales experiments appling the sodium chlorite powder ($NaClO_2(s)$) for the oxidation of NO to $NO_2$ and the carbon-based catalyst for the reduction of $NO_x$ and $SO_2$; the lab- and bench-scales experiments were conducted in laboratory and iron-ore sintering plant, respectively. In the lab-scale experiment, known concentrations of $NO_x$ (200 ppm), $SO_2$ (75 ppm), $H_2O$ (10%) and $NH_3$ (400 ppm) in 2.6 L/min were introduced into a packed-bed reactor containing $NaClO_2(s)$, then gases produced by the reaction with $NaClO_2(s)$ were fed into the carbon-based catalyst (space velocity = $2,000hr^{-1}$) at $130^{\circ}C$. In the bench-scale experiment, flue gases of $50Nm^3/hr$ containing 120 ppm NO and 150 ppm $SO_2$ were taken out from the duct of iron-ore sintering plant, then introduced into the flow reactor; $NaClO_2(s)$ were injected into the flow reactor using a screw feeder. Gases produced by the reaction with $NaClO_2(s)$ were introduced into the carbon-based catalyst (space velocity = $1,000hr^{-1}$). Results have shown that, in both lab- and bench-scales experiments, NO was oxidized to $NO_2$ by $NaClO_2(s)$. In addition, above 90% of $NO_x$ and $SO_2$ removal were obtained at the carbon-based catalyst. These results lead us to suggest that the combination of $NaClO_2(s)$ with the carbon-based catalyst has the potential to achieve the simultaneous removal of $NO_x$ and $SO_2$ at low temperature ($<200^{\circ}C$).

• Korean Chemical Engineering Research
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• v.46 no.5
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• pp.988-993
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• 2008

The characteristics of NO oxidation using sodium chlorite ($NaClO_2$) powder have been investigated by a flow type packed-bed reactor, where the reaction temperature and the space velocity are varied in the range of $20{\sim}230^{\circ}C$ and $0.4-2.2{\times}10^5hr^{-1}$, respectively, and the simulation gas mixtures are composed of NO (0~200 ppm), $NO_2$ (0-200 ppm), $O_2$ (0~15%) and $H_2O$ (0~15%) within $N_2$ balance. It has been found that the oxidation efficiency of NO depends greatly on the reaction temperature, exhibiting the existence of critical reaction temperature at about $170^{\circ}C$ where the oxidation efficiency of NO is maximized and then abruptly decreased with further increase of reaction temperature, resulting in being negligible over $190^{\circ}C$. Such a behavior in the oxidation efficiency has been originated from the phase transition of $NaClO_2$ at about $170^{\circ}C$ to form $NaClO_3$, and NaCl which are chemically inactive toward the oxidation of NO. The chemical reaction of NO with $NaClO_2$ has been observed to produce $NO_2$, ClNO and $ClNO_2$, whereas that of $NO_2$ only OClO species. Additionally, we have also observed that the introduction of $O_2$ and $H_2O$ has little influence on the oxidation of NO.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.2
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• pp.191-196
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• 2006

The injection of ozone, produced by dielectric barrier discharge, into the exhaust gas gives rise to a rapid oxidation of NO that is the main component of nitrogen oxides($NO_x$) in most practical exhaust gases. Once NO is converted into $NO_2$, it on readily be reduced to $N_2$ in the next step by a reducing agent such as sodium sulfide and sodium sulfite. The reducing agents used ca also remove $SO_2$ effectively, which makes it possible to treat $NO_x\;and\;SO_2$ simultaneously. The present two-step process made up of an ozonizing chamber and an absorber containing a reducing agent solution was able to remove about 95% of the $NO_x$ and 100% of the $SO_2$, initially contained in the simulated exhaust gas. The formation of $H_2S$ from sodium sulfide was prevented by using a strong basic reagent(NaOH) together with the reducing agent. The removal of $NO_x$\;and\;SO_2$ was more effective for $Na_2S$ than $Na_2SO_3$.

• The Korean Journal of Physiology and Pharmacology
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• v.1 no.4
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• pp.413-423
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• 1997

The importance of the kidney in the development of hypertension was first demonstrated by Goldblatt and his colleagues more than fifty years ago. Many hormones and other regulatory factors have been proposed to play a major role in the development of hypertension. Among these factors angiotensia II (ANG II) is closely involved in renal hypertension development since it directly regulates $Na^+$ reabsorption in the renal proximal tubule. Thus the aim of the present study was to examine signaling pathways of low dose of ANC II on the $Na^+$ uptake of primary cultured rabbit renal proximal tubule cells (PTCs) in hormonally defined seum-free medium. The results were as follows: 1) $10^{-11}$ M ANG II has a significant stimulatory effect on growth as compared with control. Alkaline phosphatase exhibited significantly increased activity. However, leucine aminopeptidase and ${\gamma}-glutamyl$ transpeptidase activity were not significant as compared with control. In contrast to $10^{-11}$ M ANG II stimulated $Na^+$ uptake $(108.03{\pm}2.16% of that of control)$, $10^{-9}$ M ANG II inhibited ($92.42{\mu}2.23%$ of that of control). The stimulatory effect of ANG II on $Na^+$ uptake was amiloride-sensitive and inhibited by losartan (ANG II receptor subtype 1 antagonist) and not by PD123319 (ANG II receptor subtype 2 antagonist). 2) Pertussis toxin (PTX) alone inhibited $Na^+$ uptake by $85.52{\pm}3.52%$ of that of control. In addition, PTX pretreatment prevented the AMG II-induced stimulation of $Na^+$ uptake. 8-Bromoadenosine 3',5'-cyclic monophosphate (8-Br-cAMP), forskolin, and isobutylmethylxanthine (IBMX) alone inhibited $Na^+$ uptake by $88.79{\pm}2.56,\;80.63{\pm}4.38,\;and\;84.47{\pm}4.74%$ of that of control, respectively, and prevented the ANG II-induced stimulation of $Na^+$ uptake. However, $10^{-11}$ M ANG II did not stimulate cAMP production. 3) The addition of 12-O-te-tradecanoylphorbol-13-acetate (TPA, 0.01 ng/ml) to the PTCs produced significant increase in $Na^+$ uptake ($114.43{\pm}4.05%$ of that of control). When ANG II and TPA were added together to the PTCs, there was no additive effect on $Na^+$ uptake. Staurosporine alone had no effect on $Na^+$ uptake, but led to a complete inhibition of ANG II- or TPA-induced stimulation of Na'uptake. ANG II treatment resulted in a $111.83{\mu}4.51%$ increase in total protein kinase C (PKC) activity. In conclusion, the PTX-sensitive PKC pathway is the main signaling cascade involved in the stimulatory effects of ANG II on $Na^+$ uptake in the PTCs.

• Korean Journal of Agricultural Science
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• v.36 no.1
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• pp.1-10
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• 2009

The characteristics of fruit ripening and cell wall modifications of two oriental pear fruits were compared during storage. The loss of fresh weight was lower in 'Pingguoli' than 'Niitaka', probably due to the difference in wax accumulation and skin structure. 'Pingguoli' produced much higher amount of ethylene and showed climacteric ripening pattern, but this response was not found in 'Niitaka'. A significant difference in soluble pectin contents was found, thus, the amount of water soluble pectins were much higher in 'Niitaka' at harvest but this difference was not significant at later stage of storage. A severe loss of water soluble pectins in 'Niitaka' was confirmed whereas a similar tendency was not found in CDTA soluble ones. Even the amount of $Na_2CO_3$ soluble pectins was relatively low, 'Pingguoli' contained approximately 2 times higher than 'Niitaka' and both cultivars showed an increasing tendency in $Na_2CO_3$ soluble polymers at later stage of storage. No significant difference in alkali soluble polysaccharides (hemicelluloses fraction) was found between both cultivars. There was a significant change in gel filtration profiles regardless of cultivars, especially in water soluble pectins resulting from severe depolymerization probably due to degradation of higher molecular weight pectins and loss of their side chains. In gel filtration profiles of $Na_2CO_3$ soluble pectins, neutral sugars were evenly distributed regardless of molecular size of pectic polymers but the decrease of high molecular weight fraction was found. In comparison of alkali soluble polymers, a similar trend was found, that is, there was no difference in gel filtration profiles but 'Niitaka' seemed to have longer side chains in alkali soluble polysaccharides in both 4% and 24% of KOH soluble fractions.

• Korean Journal of Materials Research
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• v.14 no.5
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• pp.338-342
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• 2004

Ni-Zn ferrite powder was obtained by wet method that was to be coprecipitated the metal nitrates, Fe($NO_3$)$_3$ㆍ$9H_2$O, Ni($NO_3$)$_2$ㆍ$6H_2$O, Zn($NO_3$)$_2$ㆍ$6H_2$O to make a high permeability material. The composition of the ferrite powder was $Fe_2$$O_3$ 52 mol%, NiO 14.4 mol%, ZnO 33.6 mol%. Ni-Zn ferrite powder was compounded by precipitating metal nitrates with NaOH in vessel at the synthetic temperature of $90^{\circ}C$ for 8 hours. Calcination temperature and sintering temperature were $700^{\circ}C$ and $1150^{\circ}C$～$1250^{\circ}C$, respectively, for 2 hours. And the other ferrite powder was also prepared by the wet ball milling that was to be mixed the metal oxides as same as the above chemical composition. We studied the properties of the powder and the electromagnetic characteristics of the sintered cores obtained from there two different processes. Wet direct process produced smaller particle size with narrower distribution of the size and more purified ferrite whose sintered cores had high permeability and high magnetization.