• Clean Technology
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• v.24 no.1
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• pp.35-40
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• 2018

$Co_3O_4$ catalysts for $N_2O$ decomposition were prepared by co-precipitation method. Ce and Zr were added during the preparation of the catalyst as promoter with the molar ratio (Ce or Zr) / Co = 0.05. Also, 1 wt% $K_2CO_3$ was doped to the prepared catalyst with impregnation method to investigate the effect of K on the catalyst performance. The prepared catalysts were characterized with SEM, BET, XRD, XPS and $H_2-TPR$. The $Co_3O_4$ catalyst exhibited a spinel crystal phase, and the addition of the promoter increased the specific surface area and reduced the particle and crystal size. It was confirmed that the doping of K improves the catalytic activity by increasing the concentration of $Co^{2+}$ in the catalyst which is an active site for catalytic reaction. The catalytic activity tests were carried out at a GHSV of $45,000h^{-1}$ and a temperature range of $250{\sim}375^{\circ}C$. The K-impregnated $Co_3O_4$ catalyst showed much higher activity than $Co_3O_4$ catalysts with promoter only. It is found that the K-impregnation increased the concentration of $Co^{2+}$ more than the added of promoter did, and lowered the reduction temperature to a great extent.

• Water for future
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• v.14 no.4
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• pp.73-81
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• 1981

More than 650 numbers of water well ranging in depth from 100M to 200M were installed in South Korean Penninsula during the last decade for the purpose of industrial use and municipal water supply. Those data were compiled and synthesized by writer to determine their hydrogeologic occurences in accordance with their geologic and areal characteristics. Rocks yielding the deep seated ground water beared in the geologic primary and secondary porosities are classified into 6 groups according to their geologic, hydrogeologic, and topographic characteristics, that are: volcanic, sedimentary, meta-sediment and/or schist, andesitic, gneissic, and granitic rocks. The order of ground water productivity of the groups is as written above. Even granitic rocks including porphyries, granite, and intermediate and basic plutonic rocks is considered to be the most poorest ground water yielding group among 6, it's average yield form a single well with average drilling depth of 116M is about 225 cubic meters per day if it's drilling site is properly located. Generally speaking, seizable geologic structures such as fractured, sheared, and faulted zone at the flat surface and valley center yield almost 310% more of deep seated bet rock ground water in comparision with minor structures of joints, bedding planes, and so on that are occured at high land. 50 numbers of water well drilled at crystalline rocks were specially checked and measured it's ground water yie 1ds at each drilled depth to determine each interval's productivity while hammer drilling was going on. The results indicate that the specific capacity and yield of each water well at a depth below 70M to 80M was almost neglegible. It means that optimum well depth of crystalline rocks, except the area having seizable geologic structures, shall be not deeper than 80M.

• Journal of the Mineralogical Society of Korea
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• v.20 no.2 s.52
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• pp.71-81
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• 2007

The marble-type dolomite from the Jasung Mine, which was farmed by duplicated affects of contact metamorphism and subsequent hydrothermal alteration, corresponds to a high-purity dolomite ranging up to above 98wt.% in dolomite contents. The dolomite contain minor impurities such as quartz, muscovite, and pyrite. It is characteristic that the dolomite is fairy Fe-rich corresponding to 0.4 wt.% due to the presence of pyrite of possible hydrothermal origin. The dolomite is nearly white-colored and constituting with subhedral crystals ranging $0.35{\sim}0.46mm$M in size, forming equigranular texture. Compared to the typical high-Ca limestone from the Pungchon Formation, the powder characteristics of dolomite is rather superior in milling efficiency, yields of fine particles, and size distribution. In addition, except for iron contents, the dolomite powder is no less superior than the limestone in quality and characteristics as fillers with respects to not only whiteness, oil absorption, and specific surface area but also shape characters such as elongation ratio, aspect ratio, and sphericity. This good characteristics of dolomite powder seem to be originated basically from comparatively higher grade and crystallinity of dolomite. Higher iron contents and the presence of sulfides prevents the dolomite from application for uses by thermal treatment, except for metallic manufacture. However, if proper ore separation procedure is available, the dolomite can be sufficiently utilized as substitutes for high-Ca limestone in most fields of filler industries.

• Resources Recycling
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• v.29 no.2
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• pp.8-17
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• 2020

In this study, adsorption and desorption characteristics of pulverized waste paper-mulberry pellet and bast fiber were measured to confirm the applicability to humidity control products. Paper-mulberry powder was classified by 710-355㎛, 355-100㎛, 100-45㎛ and less than 45㎛ and used in experiment. Specific surface area increased from 1.02㎡/g to 1.35㎡/g as the particle size decreased from 710㎛ to under 45㎛. Adsorption and desorption performance decreased in the order of 355-100㎛, 710-355㎛, 100-45㎛, less than 45㎛ and bast fiber, adsorption content on each particle sizes were 141.1g/㎡, 147.1g/㎡, 135.7g/㎡, 129.0g/㎡ and desorption content were 117.2g/㎡, 123.6g/㎡, 110.2g/㎡, 93.3g/㎡. As a result, adsorption and desorption performance of paper-mulberry powder were superior to those of the bast fiber and these phenomenon can be considered that it caused by pore distribution in pellet and damage of fiber.

• Journal of the Korean Recycled Construction Resources Institute
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• v.7 no.4
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• pp.405-412
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• 2019

In this study, the physical and chemical properties of mortar are evaluated by micro-analysis, taking into account the substitution rate(20%, 30%, and 40%) of zeolite with porous properties and active hwangtoh. First, the physical and chemical properties of zeolite and active hwangtoh are reviewed to confirm that the specific surface area of those is similar with ordinary portland cement, and the main chemical composition is SiO₂, Al₂O₃, Fe₂O₃, etc.. So, it is thought that they have the properties of pozolan reactive materials. As the results of the strength test considering the amount of substitution based on that of cement, It is confirmed that strength decreases with the increase of the replacement amount of zeolite and active hwangtoh, and the strength of mortar with replacement rate of 20% is higher than OPC mortar. It is confirmed that the amount of porosity is increased due to chemical properties of zeolite and active hwangtoh, and in particular, the size of the pore is greater than 1㎛ in mortar mixed with active hwangtoh.

• Journal of Pharmaceutical Investigation
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• v.20 no.4
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• pp.223-228
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• 1990

The contribution of endogenous transport systems to the blood-brain barrier (BBB) transport of basic and acidic drugs was studied by using a carotid injection technique in rats and an isolated bovine cerebrovascular disease state were compared between the normotensive rats (WKY) and stroke-prone spontaneously hypertensive rats (SHRSP) which have been well established as an animal model with pathogenic similarities to humans. Basic drugs such as eperisone, thiamine and scopolamine inhibited, in a concentration dependent manner the in vivo uptake of $[{^3}H]choline$ through BBB, whereas amino acids and acidic drugs such as salicylic acid and valproic acid did not inhibit the uptake. The uptake of $[^3H]choline$ by B-CAP increased with time and showed a remarkable temperature dependency. The uptake of $[^3H]choline$ by B-CAP showed the very similar inhibitory effects as observed in the in vivo brain uptake, and was competitively inhibited by a basic drug, eperisone. The in vivo BBB uptakes of $[^3H]acetic$ acid and $[^{14}C]salicylic$ acid were dependent on pH of the injectate and the concentration of drugs. Several acidic drugs such such as salicylic acid, benzoic acid and valproic acid inhibited the in vivo uptake of $[^3H]acetic$ acid, whereas amino acid, choline and a basic drug such as eperisone did not inhibit the uptake. The uptake of acetic acid by B-CAP was competitively inhibited by salicylic acid. The permeability surface area product (PS) through BBB for $[^3H]choline$ in SHRSP was significantly lower than that in WKY. The concentration of choline in the brain dialysate in SHRSP was about half of that in WKY, while no significant difference was observed in the plasma concentration of choline between SHRSP and WKY. No significant difference was observed in the transport of monocarboxylic acids, glucose and neutral amino acid through BBB between SHRSP and WKY. From these results, it was concluded that BBB transport system of choline contributes to the transport of basic drugs through BBB, that acidic drugs can be transported via a moncarboxylic acid BBB transport system and that the specific dysfuntion of the BBB choline transport in SHRSP was ascribed to the reduction of the maximum velocity of choline concentration in the brain interstitial fluids.

• The Journal of Engineering Geology
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• v.12 no.2
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• pp.215-234
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• 2002

Groundwater Dam is one of the reliable techniques to get huge amount of groundwater abstraction for municipal, agricultural, drinking, industrial water supply system. It can be a major technique to solve water shortage problems when it based on the sufficient watershed, proper topology, and adequate aquifer distribution and pollution control, Groundwater Dam had initiated its construction by RDC(former KARICO) in early eighties in Korea and 4 of it in total were added more until late eighty. However, this technique has shrunken its application due to gradually decreased yield rate after sever years of construction. After we studied several existing sites precisely, we concluded that the main reason of decreasing yield rate was come form engineering roughness on construction in early nineties. Theoretically, the technique itself seemed to be little detectives however, there were a little application in the fields in Korea. With the recent advance in engineering fields, those defects in construction would be no longer obstacle to construct underground wall and the technique could be a one of major ground water production technique in the future. It is essential to study following items thoroughly before select the appropriate site. The topography and the site of the underground wall, aquifer distribution, the specific technique for wall construction to block groundwater flow effectively and strict quality control during construction are critical. The surface and ground water monitoring data should be collected. Sustainability of the Groundwater Dam with huge groundwater abstraction in long term should be based on the long-term water balance analysis for each site. The water quality, environmental effect analysis and maintenance achedule should be also analyzed and planned in prior. It is suggested that the two consecutive underground wall in the coastal area to prevent seawater intrusion beneath a single wall.

• Science of Emotion and Sensibility
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• v.19 no.2
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• pp.35-42
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• 2016

Electrospinning is a simple and effective process for producing nanofiber with diameter range from nanometers to micrometers which have high specific surface area. Hence, medicated nanofibers can be readily fabricated using a solution containing a mixture of a plant-extracts and a polymer. It has proved that Juniperus Chinensis can be effectively used for the prevention of UV and SLS-induced advers skin reaction such as radical production, inflammation and skin cell damage. It also found that Juniperus Chinensis has efficient ingredient of antifungal activity and house dust mite repellent effect. The fabrication of PVA nanofibers containing Juniperus Chinensis extracts by electrospinning has been studied. PVA/Juniperus Chinensis extracts composite nanofibers were produced at different Juniperus Chinensis concentrations (0.25, 0.5, 1.5 wt. %). The parameters of electrospinning including polymer contents, voltage and tip-to-collector distance (TCD) were optimized for fabrication process. The study show that 12 wt. % PVA, 10kV applied voltage and TCD 10~20 cm are the best condition to obtain uniform PVA/Juniperus Chinensis extracts composite nanofibers. Morphologies of the electrospun composite nanofiber were observed by using a field emission scanning electron microscope. It has been found that the average diameters of fibers increased by the adding of Juniperus Chinensis extracts. As the results, PVA/Juniperus Chinensis extracts composite nanofibers having a diameter in the range from 310~360 nm were successfully prepared via an electrospinning.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.6
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• pp.1037-1044
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• 2000

The objective of this study is the preparation of activated carbon for BAC(biological activated carbon). Prepared activated carbon was measured iodine adsorption(mg/g). methylene blue adsorption(mg/g), B.E.T($m^2/g$), PSD(Pore Size Distribution) and 'Picabiol' which in commercial activated carbon for BAC. Activation method for this study was a chemical activation used the phosphoric acid. In the method, two important factors affected activation characterized in preparation were temperature and impregnated phosphoric acid concentration. Activation temperature and impregnated phosphoric acid concentration were changed the $600{\sim}800^{\circ}C$ and 35~50wt% respectively. Activation time was fixed for 3 hour. Optimal activation temperature was $800^{\circ}C$ and impregnated phosphoric acid concentrations was about 50wt%. By the above condition specific surface area, iodine adsorption number and methylene blue adsorption number resulted $1643.3m^2/g$, 1093 mg/g, 445.6 mg/g, respectively.

• Journal of Korean Society of Environmental Engineers
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• v.32 no.10
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• pp.965-972
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• 2010

The objective of this research was to evaluate for the changes of pore structures and adsorption capacities due to the increase the numbers of reactivation. The reactivated GAC had experienced three cycles of water treatment and thermal reactivation. The pore size distributions of virgin and reactivated GACs were very different. The virgin GAC was mostly microporous (< $15\;{\AA}$), with less mesopores ($20{\sim}100\;{\AA}$). The reactivated GACs was mostly mesoporous ($20{\sim}100\;{\AA}$), with less micropores (< $15\;{\AA}$). The specific surface area and total pore volume were reduced as the number of reactivation increased. The maximum adsorption capacity (X/M) of virgin GAC ($964.6\;{\mu}g/g$) for $CHCl_3$ was 2~3 times larger than 1st~3rd reactivated GAC ($255.6{\sim}399.5\;{\mu}g/g$). The maximum adsorption capacity (X/M) of virgin GAC (19.5 mg/g) for DOC (dissolved organic carbon) was equal to that of 1st~3rd reactivated GAC (18.0~18.7 mg/g).