• Applied Chemistry for Engineering
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• v.28 no.4
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• pp.485-489
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• 2017

Polyethylene terephthalate (PET) has been widely applied in polymers and packaging industries to produce synthetic fibers, films, drink bottles or food containers. Therefore, it has become one of the major plastic wastes. In this article, glycolysis known as one of the main methods in PET chemical recycling was investigated using a glycol to break down the polymer into a monomer. Glycolysis of PET and ethylene glycol was performed in a micro-tubing reactor under various conditions. The effect of glycolysis conditions on the product distribution was investigated at experimental conditions of the EG/PET ratio of 1~4, the reaction time of 15~90 min and the reaction temperature of $250{\sim}325^{\circ}C$ with Mn and Cu catalysts. The highest yield of bis (2-hydroxyethyl) terephthalate monomer (BHET) was obtained as 89.46 wt% under the condition of the reaction temperature of $300^{\circ}C$ and the time of 30 min using 10 wt% $Cu/{\gamma}-Al_2O_3$ catalyst, with the PET and ethylene glycol ratio of 1 : 2.

• Design & Manufacturing
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• v.14 no.2
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• pp.1-6
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• 2020

Recently, research and commercialization related to the field of cell-based therapeutic drug development has been actively conducted. In order to maintain cell viability and prevent contamination, refrigeration preservation devices, such as CRF (controlled rate freezer) or vapor type LN2 tanks have been developed. On the other hand, the storage container for liquid nitrogen tanks currently on sale minimizes the flow structure to prevent structural defects when stored in a liquid nitrogen tank having a high thermal conductivity than vapor nitrogen. If the cell-based treatment drug is stored in the gaseous LN2 tank as it is, the cell survival after thawing is greatly reduced. It was estimated that the existing storage container structure was a factor that prevented the rapid entry and circulation of gaseous nitrogen into the container. Therefore, this study intends to propose a new supercellular storage container model that can maintain the mechanical strength while maximizing the fluid flow structure. To this end, we estimated that the structural change of the storage container effects on the equivalent stress formed around the through-holes of them when exposed to a cryogenic environment using thermal-structural coupled field analysis. As a result of storage experiments in the gas phase tank of the cell-based therapeutic agent using the developed storage container, it was confirmed that the cell growth rate was improved from 66% to 77%, which satisfied the transportation standards of the FDA(Food and Drug Administration) cell-based therapeutic agent.

• Journal of Environmental Health Sciences
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• v.40 no.6
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• pp.435-441
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• 2014

Objectives: Bisphenol A, or BPA, is a chemical component in polycarbonate plastic with which many people come into contact every day. A great deal of controversy has arisen over its safety since this material, which is known to disrupt the human endocrine system and cause neurological difficulties and cancer, is commonplace in beverage containers, food can liners, and receipt paper rolls. In this study, we determined the levels of exposure to BPA of workers in the service industry depending on the number of receipts contacted. Methods: The participants were 16 male and 18 female workers employed in the service industry. Using a questionnaire, we investigated general and job characteristics. Urine samples were collected and analyzed by the LC-MS/MS technique after enzymatic hydrolysis and solid phase extraction (SPE). Results: The geometric mean (GM) concentration of urinary BPA from all subjects was 1.02 ng/ml. Workers were exposed significantly to more BPA according to the number of receipts they contacted, their work experience, and working hours per day. The BPA concentration of those who touched more than 100 receipts per day was 3.09 ng/ml, while that of the other participants was 0.61 ng/ml. It was shown that wearing gloves can protect from BPA exposure. Conclusion: We determined the urinary BPA concentrations of workers in service industry and found that the contact with receipts could increase the BPA exposure of service workers.

• Korean Journal of Agricultural Science
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• v.49 no.4
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• pp.923-931
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• 2022

An increasing global population requires a greater food supply, and accordingly there is demand for enhanced production of rice, as a major crop plant that covers half of the world's population. Rice production in arid area is extremely difficult due to poor soil fertility, salinity, deficit of irrigation water, and weather conditions. The aim of the present study was to determine whether various fertilization recipes could provide a countermeasure to allow rice production while also providing soil amendment such as soil pH adjustment. The study was conducted at an experimental field of the United Arab-Emirates (UAE) from January to April, 2022. Rice seedlings (cv. Asemi, alkaline-resistant) were transplanted in plastic containers, and different types of water and nutrient managements were employed as follows: water management (flooding and aerobic for NPKs treatment group) and nutrient management (NPKs, slow release fertilizers [SRFs] and SRFs + NPK-1 treatment groups with flooding). Water and nutrient management did not show any effect on soil pH adjustment. Rice growth was significantly enhanced in the flooding compared to the aerobic condition, whereas the effect of nutrient management clearly differed among the treatment groups, with SRFs + NPK-1 showing the best results followed by SRFs and NPKs. Most of the fertilization groups markedly accumulated soluble sugars in the shoots and grains of rice plants, but concomitantly a decrease in the roots. Overall, the level of starch showed a tendency of relatively slight perturbation by fertilization. Taken together, the results indicate that soil physical structure should be preferentially amended to find the key for suitable rice production.

• Current Research on Agriculture and Life Sciences
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• v.5
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• pp.81-88
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• 1987

This study was conducted to determine the contents of heavy metals in Jeotkals (salted-fermented fish and shellfishes) and to investigate the major factor of their contamination. The results were as follows : Average contents of heavy metals in Jeotkals were Hg 0.076 ppm, Pb 0.677 ppm, Cd 0.112ppm, As 1.025ppm, Cu 3.540ppm, Zn 11.230ppm and Mn 2.041ppm, those in fish and shellfishes were Hg 0.051ppm, Pb 0.425ppm, Cd 0.071ppm, As 0.632ppm, Cu 2.ppm, Zn 8.052ppm, Mn 1.178ppm and Hg ND, Pb 0.05ppm, Cd 0.01ppm, As 0.02ppm, Cu 0.087ppm, Zn 0.068ppm and Mn 0.044ppm in salts. During the fermentation of the salted anchovy (Engraulis Japonicus) in each containers, the contents of Hg and Cd had little difference with control, but Pb was high in pottery and iron container and As was in iron and regenerated plastic container. During the fermentation of the salted anchovy in iron container, the contents of heavy metals increased and was to determined more at the later stage of fermentation than at the early stage. Most contents of heavy metals increased in elution experiment of containers, but Hg and Cd did not detected. The concentration of salt did not affect to the elution of heavy metals.

• Food Science and Preservation
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• v.21 no.2
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• pp.239-245
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• 2014

This study was performed to provide fundamental information regarding the quality change of buckwheat soksungjang (BWS) during its storage. BWS was divided into three different containers (pot, plastic, and glass) and was stored at three different temperatures (5, 15, and $25^{\circ}C$), and the changes in pH, acidity, amino-type nitrogen, total bacterial count, and chromaticity were examined during the storage period. The pH (0 day, pH 4.37) and acidity (0 day, 2.93% acidity) of the samples, except at the 15 and $25^{\circ}C$ pots, did not show any significant change during storage, but 98 days after storage, the pH values of the 15 and $25^{\circ}C$ pots were pH 5.6 and 7.4, and their acidity values were 1.85 and 0.71%, respectively. At 98 days, the amino-type nitrogen of the $25^{\circ}C$ plastic sample had slightly increased to $0.75{\pm}0.01%$, and that of the $25^{\circ}C$ pot had drastically risen to $0.92{\pm}0.01%$. It was also shown that little change in the total bacterial count was found during the experiment period in every sample. The chromaticity results confirmed that the L (lightness), a (redness), and b (yellowness) values of the $25^{\circ}C$ pot sample showed relatively large changes during storage compared to the other samples. These results suggest that the desirable storage temperature of BWS is in the range of $5-15^{\circ}C$, and that a glass container is the most suitable container for BWS as it can reduce the quality alteration during storage.

• Food Science and Preservation
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• v.15 no.6
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• pp.847-851
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• 2008

The handling and processing of agricultural products in Korea is done manually. Small plastic boxes, nets, and corrugated cardboard boxes are used as containers during harvesting, sorting and other product handling operations. However, these practices are labor-intensive, time-consuming, require various kinds of packing materials, and are expensive because of high operating costs. To overcome these problems, the use of pallet bins with pre-cooling and storage features for handling and processing bulk farm products was investigated. The airflow resistances through bulk potato, onion and mandarin stocks were measured, and the pallet bins and a pressure pre-cooling device were manufactured. The opening ratio, bed depth and airflow rate through bulk potato, onion and mandarin in the pallet bin were defined with regression equations. The cooling rates of bulk potato, onion and mandarin were 0.8C/h ($21.7{\rightarrow}0C$, 14.5 h), 0.4C/h ($15.4{\rightarrow}.0C$, 32.2 h) and 0.7C/h ($13.7{\rightarrow}C$, 18.8 h), respectively, with the pressure pre-cooling system. Temperature deviances for storage of bulk potato, onion and mandarin were 0.12C, 0.12C and 0.17C, respectively.

• Journal of Life Science
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• v.32 no.1
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• pp.70-77
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• 2022

Endocrine disrupting chemicals (EDCs) have been attracting significant attention in modern society, owing to the increased incidence rate of various diseases along with population growth. EDCs are found in many commercial products, including some plastic bottles and containers, detergents, liners of metal food cans, flame retardants, food, toys, cosmetics, and pesticides. EDCs have a hormonal effect on the human body, which disrupts the endocrine system, notably affecting sexual differentiation and normal reproduction, and can trigger cancer as well. Recently, the association between neurological diseases and EDCs has become a hot topic of research in the field of neuroscience. Considering that EDCs negatively affect not only neuronal proliferation and neurotransmission but also the formation of the neuronal networks, EDCs may induce neurodevelopmental disorders, such as autism spectrum disorders and attention-deficit/hyperactivity disorder as well as neurodegenerative diseases, including Parkinson's disease and Alzheimer's disease. In light of these potentially deleterious outcomes, important efforts have been underway to minimize the exposure to EDCs through appropriate regulations and policies around the world, but chemicals that have not yet been associated with endocrine disrupting properties are still in wide use. Therefore, more epidemiological investigations and research are needed to fully understand the effects of EDCs on the nervous system.

• Journal of Life Science
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• v.19 no.9
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• pp.1309-1313
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• 2009

Endocrine disruptors are chemicals which can be found in our normal daily lives. Chemicals such as bisphenol A, DDT, benzophenone and phenylphenol can be easily ingested through plastic food containers and pesticides. Endocrine disruptors can be very harmful and toxic because they disrupt the normal function of the endocrine system. It has been reported that endocrine disruptions can cause fatal strikes in the cardiovascular, reproductive, and central nervous systems, and other parts of the body. Therefore we examined if benzophenone as an endocrine disruptor inhibits development in or induces malformation of chick embryos. Chick embryos which received a single injection of benzophenone ($1{\mu}g$/egg $\sim$ $500{\mu}g$/egg) via the yolk sac at designated times (6, 9, 12, 15, 18 and 21 days after incubation) were investigated. Body weight reduction was observed in middle doses ($40{\mu}g$/egg $\sim$ $60{\mu}g$/egg). High mortality rates and teratogenic signs such as abnormal wry beak and abnormal eyeballs were seen in high doses ($80{\mu}g$/egg $\sim$ $500{\mu}g$/egg). In conclusion, it is suggested that benzophenone induces malformation of chick embryos and seriously inhibits development.

• Journal of Science of Art and Design
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• v.9
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• pp.5-24
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• 2006

Human hunted and picked to survive and a vessel was made naturally to store something being hunted and picket, which was a great invention. In modern times, society changed and development of science gave us convenience in making a vessel and various kinds of store instruments which was made of pure natural material, of new stuff, such as plastic and iron. but human became to be inclined to regress into nature because of problems of environment. We can say that the representative trend is well-being, after all this is a symptom to return to life being persued by predecessors before the science civilization was developed. Ancestors have lived with nature, adapted themselves to it. For examples they have built the house which became to be a part of nature and just like it, and studied a method of storing food to eat for four seasons, then displayed a storagehouse and storage containers everywhere of the house. Now Korean has the custody of kimchi in refrigerator at every house, but our forefathers controled a timing to eat food with studying a method of storage to put to use nature. With hot wind of well-being, Korean food is becoming to be globalized, according to this, concern about the wisdom of progenitors is growing more and more. It's an example that the world shows concern seriously about the pottery, which have stored kimchi for a long time fleshly, in globalization of kimchi. This study have three purposes, the first. checking documents about the development history of pottery which is a kind of ceramic, and then the second, through an scientific experiment, with studying characteristic of pottery being built by the wisdom of ancestors, informing the merit of pottery and necessity to the world, and futhermore, the third, working up the development of close environmental vessels putting to use the characteristic of pottery.