• Transactions of the Korean hydrogen and new energy society
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• v.22 no.2
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• pp.184-190
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• 2011

The membrane properties (membrane resistance and ion exchange capacity) of the five types of commercial anion exchange membrane, i.e. IOMAC, AHT, APS, AHA, AFN, were evaluated for the application in the alkaline electrolysis. The membrane resistance decreased in the order; in 1M KOH: AHT>IOMAC>AHA>AFN>APS; in 1M NaOH: AHT>IOMAC>AHA>APS>AFN. The ion exchange capacity decreased in the order: AFN>APS>AHT>AHA>IOMAC. The membrane life was determined from the change of membrane resistance in 1M KOH and NaOH with an increase of soaking time in 20 wt% KOH and 30 wt% NaOH solution. AHA membrane had a good membrane life in 20 wt% NaOH with its unchanged membrane resistance. And, AFN and AHA membrane had a good membrane life in 30 wt% NaOH with its unchanged membrane resistance.

• Journal of Korean Society for Atmospheric Environment
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• v.31 no.6
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• pp.538-547
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• 2015

Test activated carbon fiber (ACF) was prepared from Polyacrylonirile (PAN) through oxidation and chemical activation. Immersion of ACF precursors in the aqueous KOH solution enhanced the surface structure, as examined by BET pore analysis. Specific surface area increased greatly from less than $70m^2/g$ to $1226m^2/g$ with 4 M KOH, and total pore volume also rose up to $0.483cm^3/g$. In particular, it was found that micropores favorable for $CO_2$ molecule capture occupied more than 95%. Maximum $CO_2$ adsorption capacity was 3.59 mmol/g at 298 K. Low depth of pores in the present ACF may facilitate the molecules' desorption for its regeneration.

• Korean Journal of Metals and Materials
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• v.47 no.11
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• pp.748-753
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• 2009

The surface morphology and the surface roughness of n-type SiC induced by wet-treatment using 45% KOH and buffered oxide etchant (BOE-1HF : $6H_2O$) were investigated by atomic force microscopy (AFM). While Si-face of SiC could be etched by alkali solutions such as KOH, acidic solutions such as BOE were hardly able to etch SiC. When the rough SiC samples were used, the surface roughness of etched sample was decreased after wet-treatment regardless of etchant, due to the planarization the of surface by widening of scratches formed by mechanical polishing. It was observed that the initial etching was affected by the energetically unstable sites, such as dangling bond and steps. However, when a relatively smooth sample was used, the surface roughness was rapidly increased after treatment at $180^{\circ}C$ for 1 hr and at room temperature for 4 hr by using KOH solution, resulting from the nano-sized structures such as pores and bumps. This indicates that porous SiC surface can be achieved by using purely chemical treatment.

• 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. $2400\;m^2/g$.

• Applied Chemistry for Engineering
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• v.18 no.5
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• pp.522-526
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• 2007

Structural features and electrochemical performances of cokes pyrolized from oxidized cokes were examined, and compared with KOH-activated coke. Needle cokes ($d_{002}=3.5{\AA} $), having a graphene layer structure, were changed to a single phase of graphite oxide after oxidation treatment with an acidic solution having an $NaCLO_3$/needle coke composition ratio of above 7.5, and the inter-layer distance of the oxidized coke was expanded to $6.9{\AA} $ with increasing oxygen content. After heating at $200^{\circ}C$, the oxidized coke was pyrolized to the graphene layer structure with inter-layer distance of $3.6{\AA} $. However, the change of the inter-layer distance of the needle coke was not observed in the KOH activation process. On the other hand, an intercalation of electrolyte ions into the pyrolized coke, observed at first charge, occurred at 1.0 V, in which the value was lower than that of KOH-activation coke. The cell capacitor using pyrolized coke exhibited a lower internal resistance of $0.57{\Omega}$ in 1 kHz, and a larger capacitance per weight and volume of 30.3 F/g and 26.9 F/ml at the two-electrode system in the potential range 0~2.5 V than those of the cell capacitor using KOH-activation of coke. This better electrochemical performance may be associated with structure defects in the graphene layer derived from the process of the inter-layer expansion and shrinkage.

• Journal of Korean Society of Forest Science
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• v.35 no.1
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• pp.24-32
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• 1977

According to the chlorous salt method, most of holocellulose whose lignin was removed, was obtained. In extracting xylan from holocellulose by the different densities of alkali, 5% KOH was extracted three times but still there remained part of xylan in it and another composite of hemicellulose and cellulose was obtained. The extraction of 10% and 20% KOH showed a desirable result. Rather than the ordinary method to use a large quantity of ethanol in the precipitation isolation of xylan, the method to use a small quantity of ethanol in adopting the dialysis with cellophane-membrane by condensing density to one tenth, made il possible to extract a high purity xylan in a high retrieving rate. In isolating glucomannan, the residue of 5% KOH extraction contained a large quantity of xylan, the residue of 10% and 24% KOH extraction, also showed the same result and the comparison between glucose and mannose was approximately 1 : 1. The purification of Fehling solution made it possible to obtain comparatively pure xylan but the process of oxidation dissolution was complicated and the retrieving rate was low. This was not a good method. The ethanol titration purified a high purity xylan in a high retrieving rate and was a very excellent purifying method, considering its simple and easy process. These two purifying methods, however, could not completely remove the residue of arabinose. This will be examined and reported later.

• Electrical & Electronic Materials
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• v.10 no.5
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• pp.481-486
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• 1997

This paper describes the anisotropic etching characteristics of Si in acqueous TMAH/IPA solutions. The etch rates of (100) oriented Si crystal planes decrease with increasing TMAH concentration and IPA concentration. Etchant concentration and etch temperature have a large effect on hillock density. Hillock density strongly increase with lower TMAH concentration and higher etch temperature. The etched (100) planes are covered by pyramidal-shaped hillocks below TMAH 15 wt.%, but very smooth surface is obtained TMAH 25 wt.%. The addition of IPA to TMAH solution leads to smoother surfaces of sidewalls etched planes. Undercutting ratio of pure TMAH solution is much higher than KOH. But, addition of IPA to TMAh the underrcutting ratio reduces by a factor of 3∼4. Therefore, acqueous TMAH/IPA solution is able to use as anisotropic etchant of Si because of full compability with IC fabrication process.

• Journal of the Korean Electrochemical Society
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• v.6 no.2
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• pp.158-160
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• 2003

We have reported to make nanostructured cobalt oxide electrode that have large capacitance over than 400 F/g (specific capacitance) and good cycleability. But, it had serious demerits of low voltage range under 0.5 V and low power density. Therefore, we need to increase voltage range of cobalt oxide electrode. We report here on the electrochemical properties of sol-gel-derived nanoparticulate cobalt xerogel in 1M KOH solution and aqueous polymeric gel electrolyte. In solution electrolyte, cobalt oxide electrode had over 250 F/g capacitance consisted of EDLC and pseudocapacitance. In gel electrolyte, cobalt oxide electrode had around 100 F/g capacitance. This capacitance was only electric double layer capacitance of active surface area. In solution electrolyte, potassium ion as working ion reacted with both of layers easily. However, In gel electrolyte, reacted with only surface-active layer. Itis very hard to reach resistive layer. So, we have studied on pretreatment of electrode to contain working ions easily. We'll report more details.

• 한국정보통신설비학회:학술대회논문집
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• 2007.08a
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• pp.289-292
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• 2007

FTTH (Fiber to the Home) is constructed with optical devices and optical cables from central office (CO) to subscribers. With FTTH, it is possible to provide service platform in order to meet the customers' emerging demands for more bandwidth/security and diverse IP multimedia applications including high definition (HD) video streaming service. FTTH can provide enough bandwidth from 100Mbps to several Gbps per subscriber. It is also most appropriate network architecture for convergence of communication and broadcasting. So, FTTH is thought the final destination of telecom operators, since it is the fastest and most reliable solution so far and various IP multimedia services are possible through it. In this paper, newly attempted technologies of FTTH construction for apartment complexes using CWDM-PON system are discussed.

• Journal of the Korean Ceramic Society
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• v.23 no.1
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• pp.27-32
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• 1986

This study is aimed at synthsizing high dielectric material (Ba, Sr)$TiO_3$ through direct wet process. Pure and ultra fine particle of (Ba, Sr)$TiO_3$ Powder was synthesized from $BaCl_2$ $SrCl_2$ and TiCl4 aqeous solution at KOH Solution in the $N_2$ gas atmosphere. $BaCl_2$ $SrCl_2$ and TiCl4 were Mixed with the mole ratio of 1:9, 3:7:10, 5:5:10, 7:3:10, 9:1:10 and sythesized at 4$0^{\circ}C$~9$0^{\circ}C$ for 10min~15hrs. The particle size particle shape crystallinity and synthesis condition of (Ba, Sr)$TiO_3$ powder with the variation of temperature and reaction time in the aqueous solution studied by the exprimental instruments of DTA. TGA, X-ray diffratometer SEM.