• Food Science and Preservation
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• v.24 no.8
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• pp.1094-1102
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• 2017

Hazardous metals leaching experiment was carried out in accordance with various usage environments for camping cooking utensils distributed in the market. There was a significant difference in the degree of migration for lead, arsenic, cadmium and nickel defending on the solvent and how to use, although they were all appropriate for criteria. In general, the migrated amount of aluminum was increased in acidic condition, and the migrated amount of arsenic was increased in salty condition. Physical scratches increased the overall release of hazardous metals from the portable pots and pans for camping in all solvents. Especially, in 0.5% citric acid solution, cadmium was migrated by physical scratch in stainless steel and hard aluminum pots and pans. The longer the leaching time, the higher the migration of aluminum in acid condition and arsenic in basic condition. From these results, it is desirable to use the cooking utensil for camping without being exposed to strong acidic or basic solution and scratches in order to reduce the migration of hazardous metals from them.

• Korean Journal of Food Science and Technology
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• v.44 no.3
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• pp.274-279
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• 2012

The objective of this study was to develop oral matrix tablets for the sustained release of vitamin C. In this study hydroxypropyl methylcellulose (HPMC) has been utilized as an excipient, as it is one of the most widely used polymers, for use during long periods of time in formations. The vitamin C tablet formulation depends on the molecular weight and concentration of sustained-delivery in HPMC. Anti-oxidants have been added as a dissolution medium in order to prevent vitamin C degradation in water. The dissolution test was carried out in a distilled water medium, and the release model equation was applied to analyze the vitamin C release pattern. The results demonstrated that the release and lasting power of vitamin C tablets, containing HPMC, lasted for more than 12 h.

• Journal of Soil and Groundwater Environment
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• v.11 no.1
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• pp.23-36
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• 2006

Experimental leaching of tailings was performed as a function of times (1, 2, 4, 7, 14, 21 and 30 days) in the laboratory using reaction solutions equilibrated to three different pH set-points (pHs 1,3 and 5). The initial pHs of 5 and 3 stabilized at either 4.6-6.1 or 2.8-3.5 in 2 days and decrease gradually with time afterwards. The results of the leaching tests indicate that the significant increase in the sulfate concentrations and in acidity after 7 days of leaching results from the oxidation of sulfide minerals. There were no significant variations in the extractable Pb found in the leach solutions of pH 5 and 3 within the reaction time (1-30 days), while Zn, Cd and Cu concentrations tend to significantly increase with time. In tailings leaching at an initial pH=1, two trends were observed: i) The 'Zn-type' (Zn, Cd and Cu), with increasing concentrations between days 1 and 30, corresponding to the expected trend when continuous dissolution is the dominant process, ii) the 'Pb-type' (Pb), with decreasing concentrations over time, suggesting rapid dissolution of a Pb source followed by the precipitation of 'anglesite' in relation to the large increase in dissolved sulfates. The high sulfate concentrations were coupled with high concentrations of released Fe, Zn and Cd. Release of Zn and Cd and acidity from these leaching experiments can potentially pose adverse impact to surface and groundwater qualities in the surrounding environment. The kinetic problems could be the important factor which leads to increasing concentrations of trace metals in the runoff water.

• Journal of Soil and Groundwater Environment
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• v.8 no.2
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• pp.62-69
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• 2003

The aim of research is the evaluation of the $Cr^{6+}$ emission features of the liquid injection through emission experiments in varying conditions, based on a field-mixing ratio. The results showed that the content of $Cr^{6+}$ content in cement measured had an Ordinary Potland Cement (OPC) of 25.3 mg/kg, which constitute the largest portion among the other materials. Likewise, the emission experiment of homo-gel and sand-gel generally satisfied the standard of KSLT (Korea Standard Leaching Test) in waste of 1.5 mg/L, but in case of the standard of KSLT in soil the emission of OPC $Cr^{6+}$ of 4.85 mg/kg. These conditions is a little exceeded the criteria in the ‘Ga’ area in terms of Korea Soil Environmental Preservation Law. In addition, results generated by the mock-up injection facilities revealed that $Cr^{6+}$ emission increased as Water/Cement and injection pressure increased. At injection pressure higher than 4 kg/㎤, $Cr^{6+}$ emission exceeded the water preservation standard of 0.5 mg/L. Similarly, a pattern experiment of C $r^{6+}$ emission according to pH was conducted, in order to evaluate the $Cr^{6+}$ emission features of grout materials in leachate below pH 5 such as pH 4 acid rain or landfill. Results show that $Cr^{6+}$ emission dramatically increased in high acidic or basic state. It indicates that $Cr^{6+}$ emission will probably increase in an environment where grout materials are injected. On the other hand, concentration of leachate was determined in areas where grout materials are used. The results show that the concentration of emission in an ultra purity condition does not manifest intensity, and is affected in the OPC>MC>SC order. It means that the pollutants or $Cr^{6+}$ emission increases with decreasing concentration. As such, $Cr^{6+}$ emission will probably exceed the countermeasure criteria according to the types of gout materials. Similarly, high pressure or injection will cause increased $Cr^{6+}$ emission. Therefore, the selection of materials or mixing ratio should be considered in general as well as according to specific industries, based on the strength and pH of $Cr^{6+}$ emission.

• Korean Journal of Ecology and Environment
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• v.39 no.3 s.117
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• pp.331-339
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• 2006

This research was carried out to understand the impacts of thickness of sand capping to control phosphorus release from sediment into overlying water. As capping effectively retards release flux, phosphorus concentration in water body can be maintained if phosphorus release rate was kept under microbial degradation rate. With capping thickness increases, deaeration rate become less, while reaeration coefficient become higher. Phosphorus release rate and capping thickness were linearly correlated. The results of regression analysis indicated that phosphorus release can be controlled effectively by sand capping of least 20${\sim}$40 mm thickness.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.09a
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• pp.1095-1099
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• 2009

In general, slope failures are occurred by the interaction among various factors(slope shape, hydraulic condition, and geologic condition, etc.). Hydraulic condition was a very important factor of a stability in cut slope and a dangerous of road passing. In this study, two cut-slope case on prescription of spring out water present. And this study data is used at practical affairs.

• Economic and Environmental Geology
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• v.38 no.4 s.173
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• pp.395-409
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• 2005

To explore submarine groundwater discharge (SGD) into the coastal zone of Jeju Island, the water quality analysis with seasonal remotely sensed data was carried out. If the groundwater is directly discharged into the ocean, the water quality of coastal zone is influenced. Therefore sea surface temperature (SST), the transparency, and Chlorophyll-a's concentration were analyzed for extracting the anomaly zone related with SGD using Landsat Thematic Mapper (TM) data acquired on April, August, and December. Then the spatial characteristics of springs, which located along the coastal area, were analyzed by CIS data integration based on Fuzzy logic. The integration results were compared with the anomaly zone extracted from Landsat TM data, and it is considered that springs has close relationship with SGD.

• Journal of the East Asian Society of Dietary Life
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• v.9 no.4
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• pp.483-488
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• 1999

Effect on iron dissolution from iron sauce pans treated with the acetic, malic, citric acid and concentration(0. 0.02. 0.04. 0.1, 0.2, 0.4. 1.0, 2.0, 4.0%) of acidity, boiling times(0, 10. 20, 30, 40, 50, 60mins.) and temperature(5, 20, 40. 60, 80, 10$0^{\circ}C$) of acidity solution and in new and used sauce pans was investigated. As acetic acid concentration increases, iron content has increased. Iron dissolution concentration from iron sauce pan for boiling in malic acid increased more than that of acetic acid and citric acid. At above 6$0^{\circ}C$, as temperature increases, concentration of iron dissolved from iron sauce pan has increased. As boiling time increases, concentration of iron dissolved from iron sauce pan has also increased. Concentration of iron by repeated use has increased. And iron concentration has dissolved in large amount from new pan rather than used pan. Concentration of iron with distilled water by repeated use has increased only slightly. But 1% acetic acid has dissolved in large quantities.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2007.11a
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• pp.13-13
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• 2007

Ni-Fe 합금을 전주성형하여 Ni용출 특성을 연구하였다. 피팅현상은 Ni용출을 가속화시키나 전주성형된 Ni-Fe 합금의 나노구조는 피팅현상을 줄임으로써 Ni용출량을 줄이는 역할을 함을 알 수 있었다. Ni 용출시험은 인공땀 용액에서 수행하였다.

• KSBB Journal
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• v.14 no.3
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• pp.371-376
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• 1999

Simulation of preparative protein chromatography becomes necessary for separation as well as optimal operation. A mathematical model describing the behavior of elution peaks in preparative protein chromatography for single and binary component separation was solved numerically using a PDEsolver Macsyma$^{\circledR}$(Macsyma Inc., Arlington, MA, U.S.A.). Band profiles were calculated with the equilibrium-dispersive model of chromatography. The effects of the sample volume, concentrations of solutes in the sample, flow velocity and column length on the band profile of the elution peaks are discussed. The results in this paper suggest the model simulation for the binary mixture can be extended to multicomponent separations.