• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.33 no.1
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• pp.6-11
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• 2023

Objective: This study was conducted to identify the cause of suffocation accident. Methods: We analyzed the components of zinc concentrates by ICP-OES (inductively coupled plasma optical emission spectroscopy) and tested the oxygen consumption by zinc concentrates in a 13.2-liter closed chamber. Results: Zinc, sulfur and iron were the main components of the four types of zinc concentrates, and accounted for 76~89% by weight. Zinc concentrates (0.5 or 0.927 kg) depleted the oxygen concentration from 20.9% to 7.4~18.9% during seven days. The rate of oxygen consumption was in the range of 3.0~11.0 mM/day·kg-sample at 21~24℃ and around 95% of free air space within the closed chamber. Conclusion: Since zinc concentrate consumes oxygen in a confined space, measures should be taken to prevent suffocation accident (such as ventilation and monitoring of oxygen concentration).

• Korean Chemical Engineering Research
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• v.50 no.5
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• pp.808-814
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• 2012

Photocatalytic zinc oxide powders were prepared from precursor zinc acetate and ammonia solution at elevated temperature, $80^{\circ}C$, by hydrothermal precipitation method. The effect of operating parameters, pH of ammonia solution and concentration of zinc acetate solution, on the characteristics of zinc oxide powders were experimentally examined. Zinc oxide powders prepared at the conditions of pH 11, zinc acetate concentration of 1.0 M, precipitation temperature of $80^{\circ}C$, showed smallest average particle diameter of $3{\mu}m$. SEM and XRD analysis confirmed that prepared zinc oxide has hexagonal rods structure, and Anatase type crystallinity. In addition, DRS and PL analysis showed that the zinc oxide has activity at the range of 200~400 nm of UV light. And the zinc oxide decomposed 57% of a food-color stamp Brilliant blue FCF for 3 hours under the UV radiation.

• YAKHAK HOEJI
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• v.40 no.5
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• pp.501-506
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• 1996

This study was conducted to investigate on the changes of copper and zinc concentration in rat's tissues and urine after cadmium administration with atomic absorption spectroph otometric method. It is found that cadmium appeared to cause a change in the behavior of copper and zinc in vivo system even during 1 month after cadmium treatment.

• Korean Chemical Engineering Research
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• v.48 no.2
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• pp.218-223
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• 2010

The zinc oxide thin film, which can be applied as the gas sensor of a semiconductor type, was grown on the silicon substrate by CFR(continuous flow reaction) method in this study. The growth property and the electrical property of the zinc oxide thin films synthesized by CFR method were also investigated. Zinc acetate solutions of 0.005~0.02 M were used as the precursor for the preparation of zinc oxide thin films. The size of ZnO particles consisted on the zinc oxide thin film increased not only with increasing concentration of precursor, but also the thickness of thin film increased. The growth rate of zinc oxide thin film by CFR method was proportionably depend on the concentration of precursor and the uniform ZnO thin film was prepared when zinc acetate of 0.01 M is used as the precursor. The charged currents on the zinc oxide thin films were obtained as its electrical property by I-V meter, and increased agree with increasing the thickness of zinc oxide thin film. Thus, it was concluded that the charged current on the zinc oxide thin film can be controlled with changing concentration of precursor solution in CFR method. The charged currents on the zinc oxide thin films also decreased when ZnO thin film is exposed under hydrogen sulfide of 500 ppmv at $300^{\circ}C$ for 5 min. From these results, it could be confirmed that the zinc oxide thin film prepared by CFR method can be used for the detection of sulfur compounds.

• YAKHAK HOEJI
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• v.40 no.6
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• pp.659-665
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• 1996

Zinc white is mainly used as a mild astringent, protectant. and has weak antiseptic action. It is well known that the yield of zinc white produced is greatly affected by the syn thetic conditions such as the reactant concentration, reaction temperature, washing water temperature, mole ratio of reactants, and drying temperature, calcination temperature, etc. The purpose of this study is to investigate the optimal synthesis conditions of zinc white produced. A randomized complete block design suggested by G.E.P. Box and K.B. Wilson was applied for this purpose. Basic zinc carbonate was prepared by reacting zinc sulfate and sod. carbonate solution in this study. Zinc white comes when prepared by calcination of basic zinc carbonate. The optimum synthesis conditions of zinc white obtained from this study is as follows: 1) The reacting temperature range is: 92-100$^{\circ}C$, 2) The concentration of reactant solution is 23.6-27%, 3) The optimum mole-ratio: [ZnSO4]/[Na2CO3] is 1.74~1.96, 4) The washing water temperature is 36$^{\circ}C$, 5) The drying temperature range is 68-74$^{\circ}C$, 6) The calcination temperature is 600$^{\circ}C$. The outcome of DSC indicated a desolvation of basic zinc carbonate occurred at about 133.3$^{\circ}C$. The dehydration of the compound ceased at about 267.9$^{\circ}C$ and the decarboxylation ceased at about 379.9$^{\circ}C$. The physical and chemical properties of zinc white as medicine were studied by use of Volume Test.

• Analytical Science and Technology
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• v.8 no.1
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• pp.101-105
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• 1995

The concentration of zinc of the Reumatoid Arthritis patients has been determined by ICP-AES, and the analytical results are discussed. It is observed that the zinc concentration is largely affected by the length of scalp hair. The concentrations of zinc in the distal end are much higher than that of the proximal end.

• Journal of the Korean Chemical Society
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• v.55 no.4
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• pp.575-580
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• 2011

It was investigated into the effects on zinc corrosion of the rotation speed of Zn-RDE and the oxygen concentration in borate buffer solution. Zinc corrosion was heavily influenced on the rotation speed of electrode and the oxygen concentration. We have suggested the disproportion reaction following the reversible one electron transfer as the corrosion mechanism of zinc.

• Proceedings of the KIEE Conference
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• 2005.07c
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• pp.1873-1875
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• 2005

The effect of zinc oxide as an inhibitor for the corrosion of steel in concrete environment was studied by weight loss measurements, potential-time behaviour and anodic polarization technique. The salient features of the investigation were: in 100% OPC extracts, the passivity of steel was readily destroyed, however extracts containing various concentration of zinc oxide, the passivity of steel was maintained even in the presence of 30,000 ppm of chloride. Alkalinity of concrete was maintained by the addition of zinc oxide. The efficiency of the inhibitor was found to increase with increasing inhibitor concentration. Addition of zinc oxide in the range 3 to 4% by weight of cement was sufficient to protect the rebars.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.07a
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• pp.731-734
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• 2000

The characterization of Zinc diffusion processes applied fur high-speed avalanche photodiodes has been examined. The different diffusion process conditions for InP test structures were explored. The Zinc diffusion profiles, such as the diffusion depth and the Zinc dopant concentration, were examined using secondary ion mass spectrometry with varying the process variables and material parameters. It is observed that the diffusion profiles are severely impacted on the process parameters, such as the amount of Zn$_3$P$_2$source and the diffusion time, as well as material parameters, such as doping concentration of diffusion layer. These results can be utilized for the high-speed avalanche photodiode fabrication.

• Asian-Australasian Journal of Animal Sciences
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• v.33 no.5
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• pp.825-835
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• 2020

Objective: The aim of the present study was to investigate the effect of dietary zinc supplementation of Friesian cows on chemical-nutritional and aromatic properties of Caciocavallo cheese after 7 days (C₇) and 120 days (C₁₂₀) of ripening. Methods: Twenty eight Friesian cows, balanced for parity, milk production and days in milk, were randomly assigned to 2 groups. The control group (CG) was fed with a conventional complete diet, while the experimental group (zinc group, ZG) received a daily zinc supplementation of 60 mg for kg of dry complete feed. During the experimental period, the milk yield was monitored and samples of milk and caciocavallo cheese were collected and analyzed for chemical-nutritional composition and aromatic profile. Results: The enrichment of dairy cows diet with zinc, did not influence milk yield and composition, however a marked reduction of somatic cell count was evidenced. Both in milk and cheese the ZG samples were characterized by a lower concentration of satured fatty acids and an increase in oleic, vaccenic and rumenic acids. The aromatic profile of dairy products was also positively affected by dietary zinc intake, with an increase in concentration of carboxylic acids, esters and lactones. Conclusion: The present results suggest a positive role of dietary zinc intake in improving the quality of bovine milk and related cheese, in particular for the increase in concentration of bioactive fatty acids such as rumenic acid. The changes evidenced in cheese through the analysis of the volatile profile, would be consistent with the development of interesting organoleptic properties, although further evaluations should be performed to confirm the consumer acceptability of these changes.