• Journal of Food Hygiene and Safety
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• 제16권4호
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• pp.333-341
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• 2001

The actual overall migration data obtained from plastic food packaging materials into food simulants under high temperature testing conditions as described in the regulations of European Union, USA, and Korea or Japan were compared. Overall migration values(OMVs) with non-fatty food simulants under high temperature conditions were observed to be generally below 2.5 mg/dm$^2$ except polyamides(CPA and PA 6,6) which were tested at 121$^{\circ}C$ for 2 hrs. As for the fatty food simulants, the OMVs with soybean oil were higher than other simulants. Among the films tested, PVC wrap showed higher OMVs ranging between 23.9 and 54.6 mg/dm$^2$than others. The OMVs were measured at higher level with the elevation of contact temperature and the extension of contact time, and in fatty food simulants rather than in non-fatty simulants. Under similar testing temperature and time conditions. the OMVs tended to be increased in polar films like PA with polar simulants, and contrarily in non-polar films like PO with non-polar simulants. It is noteworthy that a discrepancy with regard to the result of OMVs was observed for some films as a result of different migration testing methods and conditions of each country areas.

• Journal of Environmental Health Sciences
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• 제42권3호
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• pp.160-168
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• 2016

Objectives: Materials coming into contact with food may result in the migration of chemical substances into the food. To protect consumers from exposure, Regulation (EU) No. 10/2011 specifies the use of standard migration tests. Polyethylene terephthalate (PET), widely used for food packaging materials, has drawn the attention of researchers because unwanted migration of PET into food might occur when consumers reuse packaging material. The aim of this study was to predict and develop a migration model for two components, acetaldehyde and butyraldehyde in PET, into food simulants under conditions of changing pH and solvents, such as those observed in fermented foods like kimchi or sauerkraut. Methods: Using a migration model based on Fick's second law of diffusion in one dimension, the migration of acetaldehyde and butyraldehyde from PET into a simulant of fermented food at $20^{\circ}C$ over 10 days was evaluated. The simulant for fermented food was modelled as 10% ethanol for three days, followed by 3% acetic acid for seven days. Results: The migration of acetaldehyde into the 10% ethanol was 0.36 times that of a simulated fermented food system, while that of butyraldehyde was 1.34 times greater. These results may have been influenced by the chemical interactions among the migrants, polymers and simulants, as well as by the solubilities of the migrants in polymers and simulants. Conclusion: Because food simulants have a limited capacity to mimic real food systems under the current migration model, an appropriate simulant and migration test should be considered in the case of increasing acidity. Furthermore, since the accuracy of the worst-case estimation of migration predicted by the current model is severely limited under changing food conditions, food simulants and their interactions should be further investigated with respect to conservative migration modelling.

• Advances in nano research
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• 제6권3호
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• pp.243-255
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• 2018

Polystyrene granules were combined with nanosilver to form a nanocomposite film. One-side migration was conducted to test into three food simulants (3% acetic acid, 10% ethanol and 95% ethanol) at $40^{\circ}C$ temperature on different period of time (2, 4, 6, 8 and 10 days). It was found that, among the simulants, the highest migration amount was obtained with 3% acetic acid, while the 95% ethanol revealed the least migration level. Diffusion coefficients of nanosilver particles into simulants were estimated by inverse simulation using experimental data of concentration variation in the simulants. The finite element method used to solve the mass transfer equation and the numerical results indicates the sameresponse with the experimental data. The numerical results confirmed that the highest diffusion coefficient for acetic acid 3% (1.82E-10 to $1.76E-9m^2\;s^{-1}$) and the lowest diffusion coefficient for ethanol 95% from 2 to 10 days were obtained, respectively. Also, results of diffusion coefficient - concentration relation showed, the diffusion coefficient had in direct correlation with time and concentration. The results indicated that, in the 3% acetic acid, due to the increasing of diffusion coefficient of silver nanoparticles, they are released faster and distributed uniformly.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• 제23권3호
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• pp.125-132
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• 2017

The effect of food simulants on properties and light barrier function of LDPE-nano $TiO_2$ composite film has been investigated. LDPE-nano $TiO_2$ composite films were prepared with 5.0wt% $TiO_2$ content by melt-extrusion. To simulate food contact environment, according to KFDA standards and specifications for food utensils, containers and packages, food simulants were selected with deionized water, 50% ethanol, 4% acetic acid and n-heptane and composite films were immersed in each food simulant at $70^{\circ}C$, 30 min except n-heptane ($25^{\circ}C$, 60 min). A variety of material properties, including crystallinity, chemical bonds, surface morphology, mechanical, oxygen barrier and optical properties, of LDPE-nano $TiO_2$ composite film were examined with and without the food simulants treatment. As a result, under regulated migration condition, LDPE-nano $TiO_2$ composite showed extremely stable in all properties tested in the study in contact with food simulants indicating that $TiO_2$ nanoparticles are physicochemically stable and quite compatible with LDPE. Results enable us to anticipate migration of $TiO_2$ will probably not occur. To evaluate influence of migration of $TiO_2$ on food stuffs, their color, pH and acidity were observed as well.

• Journal of the Korea Institute of Military Science and Technology
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• 제17권6호
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• pp.844-852
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• 2014

PBX simulant is known to exhibit highly nonlinear behaviors of deformation such as the stress softening, hysteresis under cyclic loading, residual strain after unloading, and aging. This paper proposes a new pseudo-elastic model for PBX simulant considering stress softening and residual strain. Uniaxial loading and unloading tests at quasi-static states were carried out in order to obtain the mechanical properties of the PBX simulants. And then the Dorfmann-Ogden model is modified to make it consistent with the test result of PBX simulants. Prediction with the new model shows a good correspondence to the experimental data demonstrating that the model properly describes stress softening and residual strain of PBX simulants.

• Journal of ILASS-Korea
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• 제16권3호
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• pp.140-145
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• 2011

Gelled propellants are non-Newtonian fluids in which the viscosity is a function of the shear rate, and they have a high dynamic shear viscosity which depends on the amount of gelling agent contents. The present study has focused on the breakup process, wave development of ligament and liquid sheets formed by impinging jets with various gelling agent contents. The breakup process of like-on-like doublet impinging jets are experimentally characterized using non-Newtonian liquids. The spray shape with elliptical pattern is distributed in a perpendicular direction to the momentum vectors of the jets. Gelled propellant simulants with high viscosity jets are more stable and produce less pronounced surface waves than low viscosity jets. Gelled propellant simulants from like-on-like doublet impinging jets have the spray shape of closed rim patterns at low pressure. As the injection pressure increased, rimless patterns which were composed of ligament sheets and small droplets emerged due to the effect of the aerodynamic action.

• Journal of Sensor Science and Technology
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• 제28권3호
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• pp.139-145
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• 2019

Precautionary detection of chemical warfare agents (CWAs) has been an important global issue mainly owing to their toxicity. To achieve proper detection, many studies have been conducted to develop sensitive gas sensors for CWAs. In particular, metal-oxide semi-conductors (MOS) have been investigated as promising sensing materials owing to their abundance in nature and excellent sensitivity. In this review, we mainly focus on various MOS-based gas sensors that have been fabricated for the detection of two specific CWA simulants, 2-chloroethyl ethyl sulfide (2-CEES) and dimethyl methyl phosphonate (DMMP), which are simulants of sulfur mustard and sarin, respectively. In the case of 2-CEES, we mainly discuss $CdSnO_3-$ and ZnO-based sensors and their reaction mechanisms. In addition, a method to improve the selectivity of ZnO-based sensors is mentioned. Various sensors and their sensing mechanisms have been introduced for the detection of DMMP. As the reaction with DMMP may directly affect the sensing properties of MOS, this paper includes previous studies on its poisoning effect. Finally, promising sensing materials for both gases are proposed.

• Journal of Astronomy and Space Sciences
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• 제41권2호
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• pp.79-85
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• 2024

Nowadays, the trend in lunar exploration missions is shifting from prospecting lunar surface to utilizing in-situ resources and establishing sustainable bridgehead. In the past, experiments were mainly focused on rover maneuvers and equipment operations. But the current shift in trend requires more complex experiments that includes preparations for resource extraction, space construction and even space agriculture. To achieve that, the experiment requires a sophisticated simulation of the lunar environment, but we are not yet prepared for this. Particularly, in the case of lunar regolith simulants, precise physical and chemical composition with a rapid development speed rate that allows different terrains to be simulated is required. However, existing lunar regolith simulants, designed for 20th-century exploration paradigms, are not sufficient to meet the requirements of modern space exploration. In order to prepare for the latest trends in space exploration, it is necessary to innovate the methodology for producing simulants. In this study, the basic framework for lunar regolith simulant development was established to realize this goal. The framework not only has a sample database and a database of potential simulation target compositions, but also has a built-in function to automatically calculate the optimal material mixing ratio through the particle swarm optimization algorithm to reproduce the target simulation, enabling fast and accurate simulant development. Using this framework, we anticipate a more agile response to the evolving needs toward simulants for space exploration.

• Korean Journal of Food Science and Technology
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• 제33권4호
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• pp.416-422
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• 2001

The migration of alkylphenols from PVC packaging materials (wrap, sheet and gasket) into food simulants and foods were analyzed by reversed-phase high-performance liquid chromatography with fluorescence detection and gas chromatography with mass selective detection. Only seven nonyl phenol isomers were detected in three types of PVC food packaging materials and the content of nonyl phenol of wrap was higher than those of sheet and gasket. The contents of nonyl phenol migrated from fatty food simulants (n-heptane) were higher than those from aqeous food simulants (distilled water, 4% acetic acid and 20% ethanol) and increased with increase in temperature. Nonyl phenol in fruit juice, infant formula, and beverage was migrated from PVC gasket, olefin gasket, and olefin bottle cap, respectively. Nonyl phenol was also detected from foods even before contacting with the packaging materals.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• 제15권3호
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• pp.93-98
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• 2009

Migration levels of plasticizers, di-n-butyl phthalate (DBP), benzyl-butyl phthalate (BBP), di-n-octyl phthalate(DNOP), di-iso-decyl phthalate (DIDP) and di-iso-nonyl phthalate (DINP), di-(2-ethylhexyl) adipate (DEHA), from 46 poly(vinyl chloride) (PVC) wrap films and 54 PVC gaskets into food simulants were determined using gas chromatography/mass spectrometry (GC/MS). The method was validated with limit of detection (LOD) of $0.01{\sim}0.02\;{\mu}g/mL$ for DBP, BBP, DNOP and DEHA, and $2\;{\mu}g/mL$ for DIDP and DINP. The linearity were found to be > 0.99 for all the compounds in concentration range of $0.1{\sim}81.4\;{\mu}g/mL$, and overall recoveries were ranged from 90.4 ~ 99.6%. DBP, BBP, DNOP, DEHA, DIDP and DINP were not detected in food simulants, except 1 wrap sample from which 0.28 and $0.99\;{\mu}g/mL$ of DEHA were detected respectively when tested with 20% ethanol and n-heptane as food simulants. These values were below the regulatory limitation in European Union (EU).