• Journal of the Korea Institute of Building Construction
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• v.24 no.2
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• pp.181-191
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• 2024

In the realm of cement manufacturing, concerted efforts are underway to mitigate the emission of greenhouse gases. A significant portion, approximately 60%, of these emissions during the cement clinker sintering process is attributed to the decarbonation of limestone, which serves as a fundamental ingredient in cement production. Prompted by these environmental concerns, there is an active pursuit of alternative technologies and admixtures for cement that can substitute for limestone. Concurrently, initiatives are being explored to harness technology within the cement industry for the capture of carbon dioxide from industrial emissions, facilitating its conversion into carbonate minerals via chemical processes. Parallel to these technological advances, economic growth has precipitated a surge in construction activities, culminating in a steady escalation of construction waste, notably waste concrete. This study is anchored in the innovative production of calcium silicate cement clinkers, utilizing finely powdered waste concrete, followed by a thorough analysis of their mineral phases. Through X-ray diffraction(XRD) analysis, it was observed that increasing the substitution level of waste concrete powder and the molar ratio of SiO₂ to (CaO+SiO₂) leads to a decrease in Belite and γ-Belite, whereas minerals associated with carbonation, such as wollastonite and rankinite, exhibited an upsurge. Furthermore, the formation of gehlenite in cement clinkers, especially at higher substitution levels of waste concrete powder and the aforementioned molar ratio, is attributed to a synthetic reaction with Al₂O₃ present in the waste concrete powder. Analysis of free-CaO content revealed a decrement with increasing substitution rate of waste concrete powder and the molar ratio of SiO₂/(CaO+SiO₂). The outcomes of this study substantiate the viability of fabricating calcium silicate cement clinkers employing waste concrete powder.

• Korean Journal of Food Science and Technology
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• v.22 no.6
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• pp.659-667
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• 1990

Starch acetates were prepared by conventional method, preheat treatment, and extrusion process through acetylation of corn starch with acetic anhydride and their physicochemical properties were investigated. The optimal conditions of the acetylation of starch by conventional method(CSA) was found that starch concentration was 30%, reaction temperature $35^{\circ}C$ and pH 8.5. With increasing the molar ratio of acetic anhydride to anhydrous glucose unit from 0.03 to 0.20, DS(Degree of substitution) value of corn starch acetate prepared at the optimum condition was increased from 0.019 to 0.080, while the acetylation efficiency was decreased from 31.6% to 20.5%. In the case of the preheated (gelatinized), then acetylated starch(PSA), DS value was increased from 0.027 to 0.04 at the fixed molar ratio of the acetic anhydride with increasing preheating temperature from $60^{\circ}C\;to\;90^{\circ}C$. The DS was low as 0.02 in the case of starch acetate prepared by extrusion process(WESA). The CSA and PSA showed lowering gelatinization temperature and enthalpy than raw corn starch with increasing DS. All of starch acetates showed the increased degree of transparency, the decreased lightness and the increased yellowness as compared to the raw corn starch. WESA showed lower apparent viscosity and more close to the characteristic of the Newtonian fluid than CSA and PSA. Intrinsic viscosity was reduced in CSA and WESA, although PSA has a slightly higher one than raw corn starch. The rate of retrogradation of the gels was retarded in all starch acetates.

• Asian-Australasian Journal of Animal Sciences
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• v.19 no.9
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• pp.1283-1290
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• 2006

The effect of substituting potato by-products based silage (PBS) for concentrates on ruminal fermentation, methane production and nitrogen utilization in Holstein steers was evaluated. Three growing Holstein steers ($490{\pm}19kg$, initial body weight) were used in a $3{\times}3$ Latin square experiment with three experimental diets in which PBS was included at (1) 0, (2) 19 and (3) 27%, on a dry matter basis, replacing concentrates and wheat bran. Increasing replacement levels of PBS slightly increased dry matter (DM), organic matter (OM), NDF and ADF intakes by the steers (p<0.05). Inclusion of PBS at 19% increased crude protein (CP) digestibility of the experimental diets compared with the control (p<0.05). Substitution with PBS increased ADF digestibility and nitrogen retention (p<0.05), but did not affect energy retention. Energy loss as methane ranged between 5.0 and 6.1% of the total gross energy intake. There were no significant differences in carbon dioxide and methane production among all PBS levels, while daily methane production numerically increased with PBS inclusion. Substituting PBS for concentrates did not significantly affect ruminal pH and ammonia N concentration. Total VFA concentration, VFA molar proportions and blood metabolites were also unaffected by PBS replacement. These results suggest that substitution of PBS up to 27% of diet dry matter did not significantly increase methane production and was equal or superior to concentrates in ADF digestibility and nitrogen retention for growing steers.

• Journal of Korean Society of Water and Wastewater
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• v.32 no.3
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• pp.279-289
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• 2018

N-nitrosodimethylamine (NDMA) is a class of disinfection byproducts and a frequently detected nitrosamine with carcinogenic potentials. This review summarizes NDMA precursors, their formation mechanisms in chloraminated water, and mitigation strategies. Understanding the formation mechanism and characteristics of precursors is essential for developing a mitigation strategy. Dimethylamine (DMA), the most widely studied NDMA precursor, has an NDMA molar yield up to 3%. In comparison, a subset of tertiary amines, e.g., pharmaceuticals, generate up to 90% upon chloramination. Potent NDMA precursors, are characterized by their negative partial charge, low planarity values and molecular weight, and high bond length and $pK_a$ values. A nucleophilic substitution of tertiary amine on chloramine is a key reason for the high NDMA yield from the most potent NDMA precursors. The distribution and fate of NDMA in surface water, aquifers, and its formation in the distribution system can be mitigated through two strategies: (1) degrading or/removing NDMA after its formation and (2) pre-treatment of its precursor's prior chloramination.

• International Journal of Human Ecology
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• v.4 no.1
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• pp.25-34
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• 2003

High dietary phytate is a known factor in reducing the bioavailability of minerals such as zinc and calcium which are already chronically low in the Korean diet. This study was conducted to develop methods for reducing dietary phytate through the addition of phytate and/or the substitution of high phytate foods with low phytate foods. Ten units of phytase per 100g of uncooked brown rice were added to brown rice gruel resulted in a 16.2% phytate reduction after a 3-hour incubation period; an 18.2% reduction was produced after a 6-hour incubation period. The addition of ten units of phytase per 100g of soybean curd residue at 45$^{\circ}C$, followed by refrigeration for 3 hours, resulted in a 19.1% phytate reduction. The addition of 20 units of phytase under the same conditions reduced phytate content by 24.6%. In this study, two typical Korean meals consisting of legumes and unrefined cereals were prepared as high phytate meals; these were then compared to low phytate meals that had been prepared by treating the foods with phytase and substituting unrefined with refined cereals (i.e., brown rice with white rice, whole wheat bread with white bread). The phytate content of the two high phytate meals was 1878.2mg and 1811.8mg. After the addition of phytase and the food substitution, the phytate content of the low phytate meals was reduced to 788.9mg and 606.0mg. The phytate to zinc molar ratio of high phytate diets was 22.4 and 21.3 and 9.4 and 7.9 for the low phytate meals. These results indicate that the nutritional status of Koreans in terms zinc and other minerals can be improved by phytate reduction. This can be accomplished through the change of milling process for some cereals and/or the enzyme treatment of some high phytate food items.

• Journal of the Korean Ceramic Society
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• v.20 no.3
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• pp.236-242
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• 1983

The purpose of present study is to find the structures physical properties and their inter-relations in the system of (60-x) PbO.xMO.$40B_2O_3$ glasses where MO represents for ZnO and CdO. The experiments such as differential thermal analysis infrared spectral analysis X-ray diffraction analysis density and thermal expansion measurements have been done. From infrared spectral analysis the structural units of glasses and the corresponding crystallized glasses were com-posed of $BO_3$ triangles and $BO_4$ tetrahedra. These basic units found in $PbO-B_2O_3$ binary glass system did not charge even though the divalent metallic oxides were substituted for PbO. The structures of these ternary glasses were more coalescenced than $PbO-B_2O_3$ binary glass system. This fact was supported bydecrease in thermal expansion coeffici-ent and molar volume with substitution of divalent metallic oxide for PbO. Crystalline phases obtained from the heat treatment of the $PbO-ZnO-B_2O_3$ glasses were 4PbO.2ZnO.$5B_2O_3$ PbO.2ZnO.$B_2O_3$ and unknown phases.

• Journal of the Korean Applied Science and Technology
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• v.10 no.2
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• pp.41-47
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• 1993

Chitin was isolated from crab shells by modified Hackman's method, which was treated again with aqueous sodium hydroxide solution to give alkali chitin(sodium alkoxide of chitin). And after, the alkali chitin is allowed to react with monochloroacetic acid to synthesize 6-O-(carboxymethyl) chitin [CM-Chitin] under diminished pressure. In order to synthesize high performance CM-Chitin as hygroscopic agent, it was measured that the yield and degree of subsititution of each CM-Chitin according to molar ratio(monochloroacetic acid equivalent mol/N-acetyl-D-glucosamine residue) and their moisture-absorption and moisture-release properties were measured and compared with those of hyaluronic acid. The moisture-absorption and moisture-release properties of CM-Chitin, especially 0.8 in degree of substitution, were found quite similar to those of hyaluronic acid. The preliminary results show that CM-Chitin might be used as hygroscopic agent instead of hyaluronic acid in field of cosmetics.

• Bulletin of the Korean Chemical Society
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• v.25 no.10
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• pp.1559-1563
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• 2004

The topoisomerase II poisoning effect of certain protoberberine alkaloids is associated with anti-cancer activity. Structure-activity relationships of protoberberine analogues substituted on the ring protons reveal that substitution at the C19 position is an important determinant of biological activity. In this study, the effects of substituent modification at the C19 position on the interaction of protoberberines with DNA are determined using UV and NMR spectroscopy. The line broadening effect on aliphatic resonances, chemical shift changes of the imino protons of HP14 upon berberine and berberrubine binding to HP14, and the rate of the exchange process between protoberberine analogs bound indicate that berberrubine binds HP14 more specifically than berberine. In addition, the free HP14 is altered by the substituent at the 19-position. UV spectra of berberrubine have shown a hypochromic effect together with a slight red shift, which are usually regarded as characteristics of DNA intercalation. These results are consistent with our previous report that the berberrubine is partially intercalated with HP14 with molar ratio 1 : 1, whereas a non-specific interaction is predominant between the berberine and HP14.

• Textile Coloration and Finishing
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• v.17 no.6 s.85
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• pp.1-10
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• 2005

Disperse dyes derived from heterocyclic compounds such as phenylindole, pyridone, diaminopyridine, and carbazole have been known to exhibit high light fastness and bathochromic shift compared to the coursponding aminoazobenzene. The synthetic method to obtain diaminopyridine derivatives, which can be used as coupling components, was chlorination of pyridone with phosphorous oxychloride, followed by substitution with various primary amines. Four azo disperse dyes were synthesized by coupling four diaminopyridines with 2-cyano-4-nitroaniline as a diazo component. Structures of these dyes were confirmed by $^1H$ NMR spectroscopy. The wavelengths of maximum absorption of the synthesized disperse dyes were in the range of $517\~528nm$, and molar extinction coefficients were $45,700\~50,100$. The dyeability of four disperse dyes toward PET fiber was generally good. Wash and rubbing fastnesses were excellent, while light and dry heat fastness were good.

• Textile Coloration and Finishing
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• v.32 no.3
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• pp.150-157
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• 2020

Hexachloro-cyclophosphazene(HCCP), a formaldehyde-free flame retardant (FR), was steam-cured with triethanol amine(TEA) to impart durable flame-retardancy to cotton fabrics. While the HCCP treatment alone showed very limited resistance to repeated laundering cycles, the addition of TEA substantially improved the laundering durability of the FR cotton up to twenty laundering cycles. The extended washing resistance was accomplished by the increased nucleophilic substitution of unreacted P-Cl groups in HCCP by the TEA resulting in the more densely crosslinked FR networks. With increasing molar ratio of TEA to the HCCP up to 2, the flame retarding effectivity and the synergistic effectiveness improved to 2.8 and 1.8 respectively. TGA and microscale combustion calorimetry verified the pyrolysis and combustion behaviors of the FR-cotton, which showed lower maximum pyrolysis and combustion temperatures together with substantially decreased peak pyrolysis and heat release rate, synergistically yielding larger amounts of carbonaceous chars. The formaldehyde-free HCCP and TEA can be a durable FR finishing agents for cotton fabrics acting through a solid-phase flame-retarding mechanism.