• Applied Chemistry for Engineering
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• v.19 no.1
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• pp.51-58
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• 2008

A series of oleic acid esters containing mercaptobenzothiazole and dialkylenedithiocarbamate, which are potential environmentally friendly lubricating grease additives, were synthesized as 90% yield through several method such as nucleophilic substitution of dialkyl amine and carbon disulfide, reduction reaction, and condensation reaction. The structures of the additives were confirmed by $^1H$-NMR, FT-IR and EA analysis. The additives (1 wt%) were soluble in 100 N BO except C4-DTC-OE and soluble in soybean oil. The tribological properties as lubricating additives in 100 N BO were evaluated using 4-ball tester and the results showed as follows: Bz-thia-OE < C4-DTC-OE < Pyrro-DTC-OE < C8-DTC-OE. Whereas, the 4-ball anti-wear properties were not shown in soybean oil.

• Journal of the Mineralogical Society of Korea
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• v.16 no.1
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• pp.75-90
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• 2003

Ettringite and thaumasite were observed in some concrete. The morphology and occurrence of these minerals were closely examined by performing SEM/EDAX analyses. We also experimentally induced the concrete deterioration using $Na_2SO_4$ solution with application of various environmental conditions. The stability of these minerals and deterioration characteristics under applied experimental conditions were determined. Abundant ettringite formed by“through solution reaction”occurred in many open spaces, and some microscopic ettringite formed by "tophochemical replacement" of calcium aluminate also occurred in cement paste. Severe cracking of cement paste causing premature deterioration was often associated with ettringite location. Under specific condition, ettringite was transformed to thaumasite, tricthloroaluminate, or decomposed. Thaumasite occurred with association of ettrinsite in concrete containing carbonate aggregate being subject to dedolomitization or in some concrete being subject to carbonation. Thaumasite appears to be formed under the similar condition to the general ettringite forming condition, but it formed solid solution with ettringite by substituting pre-existing ettringite. Ettringite can also be transformed to trichloroaluminate in the presence of abundant chlorides, but trichloroaluminate changed back to ettringite in late sulfate attack. It is considered that the substitution reaction direction solely depend on the concentration of chloride and sulfate ion.

• Asian-Australasian Journal of Animal Sciences
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• v.22 no.3
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• pp.396-403
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• 2009

Male broiler chicks were fed graded levels of organic zinc (zinc-methionine) supplementation to investigate the effects of partial or complete substitution of the organic zinc source for inorganic ones on the development of lymphoid organs and immunological responses. A total of 450 day-old male broilers were distributed into groups of 10 chicks and randomly assigned to nine experimental diets during a 42-day feeding trial. Dietary treatments consisted of two basal diets supplemented with 40 mg/kg added zinc as feed-grade Zn sulfate or Zn oxide in which, Zn was replaced with that provided from zinc-methionine (ZnMet) complex at the levels of 25, 50, 75 or 100%. Two randomly-selected birds from each pen replicate were bled and then slaughtered by cervical cutting on the final day of the trial to measure leukocyte subpopulations and relative weights of lymphoid organs. Among lymphoid organs, only thymus weight was affected (p<0.05) by dietary treatments. The sulfate-supplemented birds were heavier (p<0.01) in relative weight of thymus than oxide-supplemented birds. The 10 days of age-assessed cutaneous hypersensivity reaction was stronger in chicks fed ZnMet-containing diets. Dietary ZnMet supplementation caused (p<0.05) an increase in proportion of lymphocytes and consequently a decrease in heterophil to lymphocyte ratio. Diet fortification by zinc-methionine complex increased (p<0.01) Newcastle antibody titer at 19 days of age. Also, a similar response was observed in antibody titers at 6 and 12 d after infectious bronchitis vaccine administration. There was no significant effect of replacement of dietary zinc on antibody titer against infectious bursal disease virus (IBDV) at the 6th d post-vaccine inoculation; however, at d 12 after vaccination, ZnMet-fortified diets improved antibody titer against IBDV. Although dietary inclusion of ZnMet had no marked effect on primary antibody titer against sheep erythrocytes, effective responses were observed during secondary reaction from the viewpoint of both total antibody and immunoglobulin Y (IgY) titers. From the present findings, it can be concluded that dietary supplementation with organic zinc improves both cellular and humoral immune responses. It is necessary to replace 75% of supplemental inorganic zinc with organic ZnMet complex to achieve the optimum immunological responses in broiler chicks.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.15 no.2
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• pp.144-152
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• 2005

To evaluate the effect of lead biomarkers including bone lead on neurobehavioral test in lead workers, 652 lead workers without any occupational exposure to organic solvent, mercury and arsenic were agreed to participate this study. For the control subjects 102 non-occupationally lead exposed blue collar workers in general manufacturing industries were also joined this study. All study subjects joined this study with written informed consent. The study variables of lead exposure were blood and patella lead. For the general characteristics of study subjects, standardized questionnaire regarding age, sex, past disease history, job duration, body mass index (BMI), drinking and smoking habit were provided. For the past history of neurotoxicity related diseases, all study subjects were interviewed by qualified occupational health physician. The results obtained were as follows: 1. Compared with controls without occupational lead exposure, lead exposed subjects had worse performance on all tests(p<0.05). 2. After adjustment for covariates (age, sex, job duration, education level, BMI, smoking and drinking status), the signs of the regression coefficients for blood lead were negative for 13 of the 14 tests. Blood lead was a significant predictor of poorer scores on 8 tests (simple reaction time(ms & root MSD), Trail-Making Test B, Digit Symbol Substitution, Purdue Pegboard assembly, Digit Span Test, Benton Visual Retention, and Purdue pegboard both hand). 3. After adjustment for covariates (age, sex, job duration, education level, BMI, smoking and drinking status), the signs of the regression coefficients for patella lead were negative for 12 of the 14 tests. Patella lead was a significant predictor of poorer scores on 8 tests (simple reaction time(ms). Purdue Pegboard assembly, Digit Span Test, Benton Visual Retention. Pursuit Aiming rest (no. of correct & no. of incorrect), Purdue pegboard non-dominant hand and both hand). With above results, blood lead and patella lead were associated with poorer performance of neurobehavioral tests. In addition, patella lead was confirmed to be better predictor of manual dexterity test in neurobehavioral test battery in lead workers

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.4
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• pp.53-60
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• 2017

Fly ash(FA) which is a byproduct in the coal combustion in thermal power plant contributes to pore structure densification due to pozzolanic reaction, and this leads to long-term strength development and excellent resistance to chloride penetration. In the work, compressive strength and chloride resistance in OPC(Ordinary Portland Cement) and FA-based concrete are evaluated, and the relationships are investigated considering ages. For the work, 3 different W/B (Water to Binder) ratios of 37%, 42%, and 47% are prepared, and 3 substitution ratio of fly ash(0%, 30%, and 50%) are considered as well. At the age of 28 days and 180 days, test results of compressive strength, diffusion coefficients based on Tang's method, and passed charges referred to ASTM C 1202 and KS F 2711 are obtained. With increasing replacement ratio of FA and decreasing W/B, the resistances to chlorides(diffusion coefficient and passed charge) are improved, and the results at the age of 180 days decrease to only 15% level at the age of 28 days due to pozzolanic reaction in FA 50 mixture, which shows that resistance to chloride is much dependent on age effect than strength development. After 180 days, more clear linear relationships are observed between strength and resistance to chloride.

• Korean Journal of Food Science and Technology
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• v.21 no.3
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• pp.435-440
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• 1989

The present study was attempted to investigate the mutagenicities of carbonyl compounds(methyl glyoxal, glyoxal, diacetyl, dihydroxyacetone, glycolaldehyde, glyceraldehyde and furfural) derived from Maillard reaction toward Salmonella typhimurium TA 100(base-substitution mutant) without metabolic activation . And for further Investigation of mutagenicity mechanism including desmutagenicity, active oxygen scavengers (cysteine, ${\alpha}-tocopherol$, tris (hydroxymethyl) aminomethane, catalase, ascorbic acid) and reducing agents (glutathione, sodium bisulfite) were also used. Among carbonyl compounds tested, methyl glyoxal, glyoxal, dihydroxyacetone, glycolaldehyde and glyceraldehyde exhibited mutagenicities, and methyl glyoxal showed the strongest mutagenic activity. On the other hand , the mutagenicities of carbonyl compounds were significantly suppressed by cysteine, tris (hydroxymethyl) aminomethane, glutathione and sodium bisulfite. Also, these active oxygen scavengers and reducing agents alone did not show mutagenicity in the present study.

• Applied Chemistry for Engineering
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• v.7 no.4
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• pp.768-776
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• 1996

Carbon Black has various advantageous properties such as reinforcement, tinting, weathering, chemical resistance, electrical resistance, etc., but it has poor affinity in the solution. The purpose of this study is to enhance dispersion in the aqueous solution by altering the surface characteristics. Two different treatments were applied for both channel black and furnace black respectively. Channel black was treated in alkaline solution to replace hydrogen of the carboxyl group with alkaline metal, Li, Na, K. Furnace black has few functional groups, and it was treated with $HNO_3$ to increase the number of functional group on carbon black. It was seen that the substitution of alkaline metal on the surface of channel black enhances the degree of dispersion. Also the higher the acid concentration and reaction temperature, the more the number of some functional groups on the furnace black. Reaction time was not seen to be effective.

• Clean Technology
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• v.26 no.2
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• pp.116-121
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• 2020

In this paper, the recycling of waste Ni-MH battery by-products for electric vehicle is studied. Although rare earths elements still exist in waste Ni-MH battery by-products, they are not valuable as materials in the form of by-products (such as an insoluble substance). This study investigates the recovering of rare earth oxide for solvent extraction A/O ratio, substitution reaction, and reaction temperature, and scrubbing of the rare earth elements for high purity separation. The by-product (in the form of rare earth elements insoluble powder) is converted into hydroxide form using 30% sodium hydroxide solution. The remaining impurities are purified using the difference in solubility of oxalic acid. Subsequently, Yttrium is isolated by means of D2EHPA (Di-[2-ethylhexyl] phosphoric acid). After cerium is separated using potassium permanganate, lanthanum and neodymium are separated using PC88A (2-ethylhexylphosphonic acid mono-2-ethylhexyl ester) and it is calcinated at a temperature of 800 ℃. As a result of the physical and chemical measurement of the calcined lanthanum and neodymium powder, it is confirmed that the powder is a microsized porous powder in an oxide form of 99.9% or more. Rare earth oxides are recovered from Ni-MH battery by-products through two solvent extraction processes and one oxidation process. This study has regenerated lanthanum and neodymium oxide as a useful material.

• Journal of the Korea Concrete Institute
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• v.23 no.1
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• pp.49-55
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• 2011

The distresses of alkali-silica reaction (ASR) was recently reported at highway cement concrete pavement in Korea, which showed typical cracking and spalling patterns of ARS. Korea is was no longer safe zone against ASR, needding to find a control methodology against ASR. The purpose of this research was to provide a control methodology against ASR using mineral admixtures through a series of laboratory test program. Laboratory works included the accelerated mortar bar test (AMBT) by ASTM C 1260 regulation with five types of aggregate and three types of mineral admixtures (fly ash, ground granulated blast-furnace slag and silica fume). The result of ASTM C 1260 test for five types of aggregates without mineral admixtures showed that Siltstone and Mudstone were found to be "reactive." Tuff and Andesite-1 were found to be "possiblely reactive." In case of concrete mixed with 10, 20, and 30% fly ash, all specimens except Mudstone mixed with 10% FA were found to be "non-reactive". In cases of concrete mixed with 30, 40, and 50% ground granulated blast-furnace slag and 5, 7.5, and 10% silica fume, all specimens were found to be "non-reactive." These results could be selectively applied in constructions in Korea.

• Korean Chemical Engineering Research
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• v.51 no.4
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• pp.443-454
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• 2013

Various metal ions (transition and base metals) incorporated MCM-41 catalysts can be synthesized using colloidal and soluble silica with non-sodium involved process. Transition metal ion-typically $V^{5+}$, $Co^{2+}$, and $Ni^{2+}$-incorporated MCM-41 catalysts were synthesized by isomorphous substitution of Si ions in the framework. Each incorporated metal ion created a single species in the silica framework, single-site solid catalyst, showing a substantial stability in reduction and catalytic activity. Radius of pore curvature effect was investigated with Co-MCM-41 by temperature programmed reduction (TPR). The size of metallic Co clusters, sub-nanometer, could be controlled by a proper reduction treatment of Co-MCM-41 having different pore size and the initial pH adjustment of the Co-MCM-41 synthesis solution. These small metallic clusters showed a high stability under a harsh reaction condition without serious migration, resulting from a direct anchoring of small metallic clusters to the partially or unreduced metal ions on the surface. After a complete reduction, partial occlusion of the metallic cluster surface by amorphous silica stabilized the particles against aggregations. As a probe reaction of particle size sensitivity, carbon single wall nanotubes (SWNT) were synthesized using Co-MCM-41. A metallic cluster stability test was performed by CO methanation using Co- and Ni-MCM-41. Methanol and methane partial oxidations were carried out with V-MCM-41, and the radius of pore curvature effect on the catalytic activity was investigated.