• International Journal of Concrete Structures and Materials
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• v.10 no.1
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• pp.113-124
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• 2016

This paper presents the effect of silica fume and nano silica, used individually and in combination with the set accelerator and/or hydrated lime, on the properties of class F high volume ultra fine fly ash (HV-UFFA) cement composites, replacing 80 % of cement (OPC). Compressive strength test along with thermogravimetric analysis, X-ray diffraction and scanning electron microscopy were undertaken to study the effect of various elements on the physico-chemical behaviour of the blended composites. The results show that silica fume when used in combination with the set accelerator and hydrated lime in HV-UFFA cement mortar, improves its 7 and 28 day strength by 273 and 413 %, respectively, compared to the binary blended cement fly ash mortar. On the contrary, when nano silica is used in combination with set accelerator and hydrated lime in HV-UFFA cement mortar, the disjoining pressure in conjunction with the self-desiccation effect induces high early age micro cracking, resulting in hindering the development of compressive strength. However, when nano silica is used without the additives, it improves the 7 and 28 day strengths of HV-UFFA cement mortar by 918 and 567 %, respectively and the compressive strengths are comparable to that of OPC.

• Korean Chemical Engineering Research
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• v.50 no.2
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• pp.300-303
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• 2012

Phase change of calcium carbontae crystals in crystallization of precipitated calcium carbonate was researched by adding additives such as ethylenediaminetetraacetic acid (EDTA), diethylenetriaminepentaacetic acid (DTPA), citric acid (CIT) and pyromellitic amid (PMA). At low temperature $20^{\circ}C$, calcite crystal was made. At high temperature $80^{\circ}C$, aragonite crystal was made without additives. At middle temperature $40^{\circ}C$ and $60^{\circ}C$, Aragonite crystal also made by adding EDTA, DTPA. The crystal growth of Aragonite was retarded by the presence of CIT, PMA and the single phase of calcite was made. It was found that additives were important factors to make the single phase of calcium carbonate.

• Journal of the Korean Society of Food Culture
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• v.13 no.2
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• pp.119-126
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• 1998

This study was carried out to give some help for housewives recognizing the desirable purchase of processed foods and food additives. This results were abtained as follows; In case of purchase action for processed foods of housewives confirmation of manufacturing date was the highest point(4.62). When housewives bought processed foods they considered the taste of them as first, and frequencies of processed foods intake showed the ratio of 46.6%, also it was shown to be used once a week. The order for use of processed foods were milk, milk products(butter, cheese, yoghurt, lactic bacterium beverage) 40.2% >canned foods 22.6% >meat products(ham, sausage, bacon) 20.9% > jelled fish 16.3%. Most of housewives wanted to have the knowledge and information for food additives at the highest point(4.11). The interest about food additives of housewives was shown to the order of synthetic preservative 3.86 >chemical seasoning 3.74 >synthetic sweetener 3.59 >synthetic coloring agent 3.53. Also, it was shown to be thought that the hazard factors effected on food safety were agricultural chemical residue(30.9%), environmental pollution(25.2, food additives(23.0%), and microorganism contamination(20.9%).

• Journal of the Korean Chemical Society
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• v.41 no.10
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• pp.524-534
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• 1997

Analysis of additives in cured rubber is often a difficult task for analytical chemists because of a wide variety of complex components. Conventional analyses of additives and rubbers have been done in multistep, off-line processes with large sample size and extensive sample preparations. The coumarone-indene resin, resorcinol-formaldehyde resin, and prevulcanization inhibitor have been characterized by their pyrolysis pathways and mass spectra of characteristic pyrolyzates. Pyrolysis Gas Chromatography/Mass Spectrometry (Py-GC/MS) was used in the identification of additives without any sample pretreatment. This result shows that several organic additives in cured rubber can be directly analyzed.

• Bulletin of the Korean Chemical Society
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• v.17 no.10
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• pp.879-881
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• 1996

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.10b
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• pp.265-266
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• 2002

Nano materials have great potential for development of advanced lubricating and protecting materials. Nano-particles capped by organic compound such as organic acid, dialkyldithiophosphate (DDP) are capable to disperse stably in lubricating oils, and are able to reduce wear and to increase load-carrying capacity.

• Korean Chemical Engineering Research
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• v.54 no.1
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• pp.108-113
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• 2016

A miniaturized lab-scale Cu plating cell for the metallization of electronic devices was fabricated and its deposit uniformity and profile were investigated. The plating cell was composed of a polypropylene bath, an electrolyte ejection nozzle which is connected to a circulation pump. In deposit uniformity evaluation, thicker deposit was found on the bottom and sides of substrate, indicating the spatial variation of deposit thickness was governed by the tertiary current distribution which is related to $Cu^{2+}$ transport. The surface morphology of Cu deposit inside photo-resist pattern was controlled by organic additives in the electrolyte as it led to the flatter top surface compared to convex surface which was observed in the deposit grown without organic additives.

• Proceedings of the Korean Geotechical Society Conference
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• 2000.11a
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• pp.657-664
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• 2000

Weak and soft compressible clay deposits are commonly found in natural subgrade soils. These Soils need to be stabilized for using the subbase materials of highway constructions. This paper presents that a chemical treatment using chemical additives comprised of sulfate(SO$_4$) and chloride(Cl) is evaluated for stabilizing soft clay deposits and lime. The physical and mechanical characteristics of soil-lime and additives are described by means of a laboratory study. The study results indicate that the presence of chlorides encouraged the efficiency of lime stabilization, and the use of calcium chloride with quicklime is the best additive for improving soil behavior. The treated soil with lime-calcium chloride can have the adaptability to the subbase materials of highway constructions.

• Proceedings of the KIEE Conference
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• 1997.11a
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• pp.302-304
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• 1997

Chemical structure and electrical properties such as water treeing and space charge accumulation of various raw materials(XLPE) used for power cable insulation were investigated. It was found that chemical structure was changed after crosslinking reaction and every materials have different amounts of DCP and antioxidant. Electrical properties were also changed after extraction using $CHCl_3$ and xylene. Water tree length was smaller with additives such as DCP and antioxidant and bigger with low molecular weight components of polyethylene than that of extracted samples. Heterocharge was changed into homocharge after extraction. This shows that additives and low molecular weight components of polyethylene cause the heterocharge.

• Nuclear Engineering and Technology
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• v.55 no.3
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• pp.1191-1198
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• 2023

Bentonite buffer material is a critical component in an engineered barrier system (EBS) for disposing high-level radioactive waste (HLW). The bentonite buffer material protects the disposal canister from groundwater penetration and releases decay heat to the surrounding rock mass; thus, it should possess high thermal conductivity, low hydraulic conductivity, and moderate swelling pressure to safely dispose the HLWs. Bentonite clay is a suitable buffer material because it satisfies the safety criteria. Several additives have been suggested as mixtures with bentonite to increase the thermal-hydraulic-mechanical-chemical (THMC) properties of bentonite buffer materials. Therefore, this study investigated the geotechnical, mineralogical, and THMC properties of several candidate additives such as sand, graphite, granite, and SiC powders. Datasets obtained in this study can be used to select adequate additives to improve the THMC properties of the buffer material.