• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.9
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• pp.473-479
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• 2017

Due to environmental pollution, hazards of the human body, and global warning, changes in the power train of automobiles are intensifying, and the market forelectronic vehicles is rising. Also, in order to meet the stricter emission regulations forautomobiles with internal combustion engines based on fossil fuel, the proportion of after-treatments for vehicles and vessels is increasing gradually. The objective of this study is to investigate the effectsfrom additive ceric oxide ($CeO_2$) loading amounts to improve the methane ($CH_4$) and nitric oxide (NOx) abatement ability of the natural gas oxidation catalysts(NGOC) reducing toxic gases emitted from compressed natural gas (CNG) buses. Three kinds of NGOC were prepared under the following conditions: fresh and $700^{\circ}C$ for 12hr thermal aging, and the reduction performance of toxic gases was evaluated. Fresh $1Pt-3Pd-1Rh-3MgO-6CeO_2/(Al+Z)$ NGOC containing 6wt% $CeO_2$ had the highest dispersivity of palladium (Pd) with high selectivity to $CH_4$ and improved harmful gas reduction performance. The NGOC with 6wt% $CeO_2$ loaded the least decreased in the dispersivity of the noble metal, and showed the highest reduction of harmful gases due to the thermal durability of $CeO_2$.

• Journal of the Korea institute for structural maintenance and inspection
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• v.24 no.1
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• pp.1-7
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• 2020

As of 2018, Steel slag was generated approximately 24.23 million tons. Howeve, except blast furnace slag, steel slag is a typical by-product which does not have a clearly defined purpose in recycling. Thus, countries around the world are putting great efforts into developing a purpose for the recycling of steel slag. The vast habitat foundation of marine life has been destroyed due to recent reckless marine development and environment pollution, resulting in intensification of the decline of marine resources, and a solution to this issue is imperative. In order to propose a method to recycle large amounts of by-product slag into a material that can serve as an alternative to natural aggregate, the engineering properties and applicability for each mixing factor of environment friendly porous concrete as a material for the composition of seawater purification were in this study. Regarding the nutrient elution properties, it was clear that the nutrients continuously flowed out up to an immersion time by 8 months in natural seawater; the nitrogenous fertilizer displayed excellent elution properties in this regard.

• Journal of Microbiology and Biotechnology
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• v.5 no.3
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• pp.158-162
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• 1995

The effect of carbon and nitrogen sources on the production of novel aminopeptidase M inhibitors MR-387A and B by Streptomyces sp. SL-387 has been studied. High D-glucose and ammonia concentrations (5$\%$ and 1$\%$, respectively) exerted a negative influence on the inhibitor formation. The suppressive effect of glucose on the inhibitor formation is probably caused by an effect of medium pH rather than that of cyclic AMP. To establish the optimum conditions for inhibitor overproduction, various nitrogen sources and ammonium ion-trapping agents were examined. The use of ammonia slow-releasing nitrogen sources such as soybean meal and fish meal, or ammonium ion-trapping agents such as kaoline, celite, and natural zeolite achieved the enhancement of inhibitor production. These results also indicate that inhibitor formation is affected by ammonium ion repression.

• Korean Journal of Soil Science and Fertilizer
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• v.44 no.2
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• pp.285-292
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• 2011

In order to develop livestock wastewater treatment technology by natural purification method, the optimum filter media in small-scale livestock wastewater treatment apparatus for treating livestock wastewater were studied. Removal rates of pollutants under different filter media were in the other of coarse sand ${\fallingdotseq}$ broken stone > zeolite > calcite for COD, zeolite >> broken stone ${\fallingdotseq}$ coarse sand ${\fallingdotseq}$ calcite for T-N, and calcite > coarse sand ${\fallingdotseq}$ broken stone ${\fallingdotseq}$ zeolite for T-P. Based on the above results, the optimum filter media was coarse sand in small-scale livestock wastewater treatment apparatus. To meet acceptable effluent quality standard for livestock wastewater and to improve T-N and T-P removal efficiencies, removal efficiencies of pollutants in small-scale livestock wastewater treatment apparatus with mixed filter media were studied. The removal rates of COD, SS, T-N and T-P in effluent were 84, 94, 65 and 98% in small-scale livestock wastewater treatment apparatus with mixed filter media, respectively. For increasing the T-N and T-P removals in small-scale livestock wastewater treatment apparatus, the mixed filter media are recommended.

• Applied Chemistry for Engineering
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• v.7 no.5
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• pp.849-860
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• 1996

Natural zeolites which were known to occur in sedimentary clinoptilolite, were treated by thermal and chemical methods, and their adsorption characteristics of Cu(II) were studied. Analyses by FT-IR, S. E. M, TGA/DSC, and XRD showed that the adsorption capacity of Cu(II) on the zeolite decreased gradually at the temperatures of above $400^{\circ}C$. The zeolites, which treated with NaOH and NaCl, show higher absorbility in acid solution. The adsorption rate of Cu(II) in the presence of surfactants(LAS, POE AE) on the thermally or chemically treated zeolites varied depending on pH, anion or nonion surfactants.

• Economic and Environmental Geology
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• v.55 no.1
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• pp.63-76
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• 2022

Dacitic tuffs, 97 to 118 m thick, were recovered from the lower part of the subsurface Seongdongri Formation, Janggi Basin, which was drilled to assess the potential for underground storage of carbon dioxide. The tuffs are divided into four depositional units(Unit 1 to 4) based on internal structures and particle componentry. Unit 1 and Units 3/4 are ignimbrites that accumulated in subaerial and subaqueous settings, respectively, whereas Unit 2 is braided-stream deposits that accumulated during a volcanic quiescence, and no dacitic tuff is observed. A series of analysis shows that mordenite and clinoptilolite mainly fill the vesicles of glass shards, suggesting their formation by replacement and dissolution of volcanic glass and precipitation from interstitial water during burial and diagenesis. Glass-replaced clinoptilolite has higher Si/Al ratios and Na contents than the vesicle-filling clinoptilolite in Units 3. However, the composition of clinoptilolite becomes identical in Unit 4, irrespective of the occurrence and location. This suggests that the Si/Al ratio and pH in the interstitial water increased with time because of the replacement and leaching of volcanic glass, and that the composition of interstitial water was different between the eastern and western parts of the basin during the formation of the clinoptilolite in Units 1 and 3. It is also inferred that the formation of the two zeolite minerals was sequential according to the depositional units, i.e., the clinoptilolite formed after the growth of mordenite. To summarize, during a volcanic quiescence after the deposition of Unit 1, pH was higher in the western part of the basin because of eastward tilting of the basin floor, and the zeolite ceased to grow because of the closure of the pore space as a result of the growth of smectite. On the other hand, clinoptilolite could grow in the eastern part of the basin in an open system affected by groundwater, where braided stream was developed. Afterwards, Units 3 and 4 were submerged under water because of the basin subsidence, and the alkali content of the interstitial water increased gradually, eventually becoming identical in the eastern and western parts of the basin. This study thus shows that volcanic deposits of similar composition can have variable distribution of zeolite mineral depending on the drainage and depositional environment of basins.

• Journal of the Mineralogical Society of Korea
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• v.21 no.4
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• pp.365-372
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• 2008

Because stellerite, belonging to the zeolite group, is much less common mineral than any other minerals in Korea, little mineralogical study has been done so far. Stellerite occurs on open surfaces of fractured zones in the Yucheon Granite associated with flowery tourmaline, Chongdo, Gyeongsangbuk-do. Stellerite with $3{\sim}4\;mm$ length and $1{\sim}2\;mm$ width is characterized by an equigranular and euhedral form. Flat and elongated columnar crystals show well developed (010) face. Stellerite shows an intensive alteration process, possibly due to weathering or devitrification, as evidenced by microtextural analysis of Scanning Electron Microscope (SEM). Water loss occurs at $161^{\circ}C$ while dehydroxylation occurs at $467^{\circ}C$ causing decomposition of the structure afterward. From its textural observation, it is concluded that stellerite formed rapidly at small undercooling, precipitated from residual melt during the late stage with relatively constant chemistry.

• Journal of the Korea Organic Resources Recycling Association
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• v.11 no.2
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• pp.110-116
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• 2003

This study was executed to evaluate the utilization and efficiency of the ceramic biocarrier as the promoter of decomposing on the organic matters for the composting using with pig manure by analyzing of the physico-chemical properties during composting. The treatments of this experiment were consisted of the control(C),microorganism(M), M with natural zeolite(M+Z), M with synthesized zeolite(M+SZ), and M with ceramic biocarrier(M+CZ). The process term of composting was conducted for 30days in the rapidly fermented machine(as pilot system). The results of the physico-chemical properties of the composts were as follows. The changes of temperature during composting was not relative with the microorganism and zeolite materials used in the composts. At all of the treatments were similar to changing of temp. from the initial stage to the final stage. But the added microorganism treatments were higher than control. And the entire pH value of treatments were appeared the same that above temperature result, also the M+CZ and M+SZ treatment among the treatment were higher. At the results of T-C, T-N and C/N ratio, in case of T-C value, the M+CZ treatment was highly more decreased than others. However at the T-N value, there were not the differences from the each treatment. And the C/N ratio was changed according to the changes of T-C and T-N value. Especially, at the M+CZ aud M+SZ treatments were remarkably reduced by about 21.4-23.3 value. In the result of G.I for evaluating of the compost humidity, the M+CZ and M+SZ treatments were close up approximately 110 value compared with the control(G.I value 100). Therefore, the examined ceramic biocarrier amended with compost-promoting-bacteria could be applied to the production of many high quality fertilizers. It is also expected that the results of this researches could be applied to the recycle of the organic wastes based on the experimental results of ceramic biocarrier and compost-promoting-bacteria application.

• Magazine of the Korea Concrete Institute
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• v.6 no.3
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• pp.201-214
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• 1994

The fracture process zone in concrete is a region ahead of a traction-free crack, in which two major mechanisms, microcracking and bridging, play important roles. The toughness due to bridging is dominant compared to toughness induced by microcracking, so that the bridging is dominani: mechanism governing the fracture process of concrete. Fracture mechanics does work for concrete provided that the fracture process zone is being considered, so that the development of model for the fracture process zone is most important to describe fracture phenomena in concrete. In this paper the bridging zone, which is a part of extended rnacrocrack with stresses transmitted by aggregates in concrete, is modelled by a Dugdale-Barenblatt type model with linear tension-softening curve. Two finite element techniques are shown for the analysis of progressive cracking in concrete based on the discrete crack approach: one with crack element, the other without crack element. The advantage of the technique with crack element is that it dees not need to update the mesh topology to follow the progressive cracking. Numerical results by the techniques are demonstrated.

• Journal of the Mineralogical Society of Korea
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• v.23 no.1
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• pp.39-50
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• 2010

Zeolites were formed by the alteration of volcanic glass in the volcaniclastics including tuff cone/rings and subsurface Seoguipo Formation, Jeju Island. Phillipsite and analcime were identified by X-ray diffraction and electron microprobe analysis. Si/(Si+Al) atom ratios of analcime and phillipsite were similar to that of parent basaltic glass. In comparison with the simple chemistry of analcime, phillipsite showed a range of cavity cation compositions. Na is the major cavity cations of phillipsite in the Dangsanbong and Yongmeori tuffs bearing analcime, while K and Ca in core samples of Seoguipo Formation. Microtextural analysis by scanning electron microscope showed a general sequence that early phillipsite encrustification of pores was followed by later analcime infilling. Zeolites are abundant in the older tuff cone/rings but nearly absent in the younger ones.