• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.27 no.2
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• pp.115-121
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• 2021

The evaluation of package temperature for fresh preservation of cucumber was investigated. The fresh cucumber is available in markets of Korea during whole seasons, for the help of farmer, distributor and consumer. Cucumbers were stored within cardboard boxes packaging covered with low density polyethylene (LDPE) at different temperatures (5, 10, 15 and 20℃). Changes in weight loss, hue angle, firmness, moisture content and general appearance (shape of cucumber) were investigated during storage of cucumbers. General appearance index with non-packaging decreased more than with LDPE film packaging at 5℃ and 10℃. During storage of cucumbers, general appearance index as freshness showed packaging effect at low temperature than room temperature. In the fresh weight loss, the packaged cucumbers were less reduced than that of the non-packaging ones. At color change, Hue angle of cucumber stored within low temperature with film packaging decreased gradually during storage. However remarkable change in hue angle were observed in cucumber within LDPE film packaging treatments of 15℃ and 20℃ storage. The effect of hue angle with packaging appears differently depending on the storage temperature conditions. The firmness and moisture content of cucumber flesh were not affected by packaging and storage temperature. In this experiment, cucumbers packaged with LDPE film at 5℃ and 10℃ were the most desirable for extending the quality. These results suggest that packaging of low temperature treatments in combination could be effective in prolonging the shelf life of cucumber.

• Microbiology and Biotechnology Letters
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• v.47 no.3
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• pp.332-336
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• 2019

The use of ultraviolet (UV) spectroscopy for foods is known to have a microbial inhibitory effect. UV-A having a longer wavelength than UV-C can be used for continuous or intermittent UV irradiation of food stored in containers or packages. Because UV-LED can be used effectively at a low price, this study reported the effect of UV-A 365 nm-LED on inhibiting Bacillus subtilis in accordance with the packaging conditions employed in daily use. The packaging materials were linear low-density polyethylene (LLD-PE), nylon/low density polyethylene (LDPE), polystyrene, and glass. When all packaging materials were treated with 365 nm UV-LED, B. subtilis was observed to remain inactive for 30-60 min. Further, compared with the control (-log 5), the survival rate of B. subtilis was -log 2.0-2.5 for nylon/LDPE and -log 2.58-3.61 for LLD-PE. These packaging materials showed an excellent inhibitory effect regardless of their thickness. Typically, a decrease in the viable cell count of more than 3 log indicates a 99.9% bactericidal effect. These results suggest that 365 nm UV-LED permeated the packaging material and inhibited bacterial growth.

• Journal of the Korean Society of Safety
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• v.17 no.4
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• pp.101-109
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• 2002

The electrical properties of polyethylene are changed by the superstructure. Such crystalline polymer as polyethylene or polypropylene changes crystallinity and products spherulite or trans-crystal when it is cooled slowly. In this study, after thermal treatment of LDPE at 100[${circ}C$], in silicone oil for an hour, we made specimens in order of slow cooling, water cooling, quenching according to cooling speed. Also, to study the influence of electrical properties due to the superstructure change, we analyzed physical properties and performed dielectric breakdown experiments using DC and impulse voltage Moreover we measured space charges in bulk using Laser Induced Pressure Pulse(LIPP) method. Trap level of specimen is 0.064[eV] at the low temperature region 0.31[eV] at the high temperature region in DC dielectric strength, 0.03[eV] at the low temperature region 0.0925[eV] at the high temperature region in impulse dielectric strength. As its result shows that the quantity of charges induced from the electrode surface increases with applied voltage time, and the distribution of space charges in samples increases the quantity of charges in proportion to applied voltage.

• Korean Chemical Engineering Research
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• v.58 no.2
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• pp.224-229
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• 2020

We propose a machine learning-based method for proactively detecting faults in LDPE processes and predicting equipment lifespan. It is important to detect and prevent unexpected faults in chemical processes in order to maximize safety and productivity. Since LDPE process is a high-pressure process up to 3,000 kg/㎠g or more, once ESD occurs, it can result in productivity loss due to increased maintenance periods. By collecting key variables operation data of the process and using unsupervised machine leaning methods, we developed a fault detection model which detected 4 ESDs 2.4 days prior to the occurrence. In addition, it was confirmed that the life expectancy of a hyper compressor can be predicted by using the physically significant key variables.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.10
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• pp.6655-6665
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• 2015

Due to tightened environmental regulations on halogen type flame retardants, the portions of those based on phosphorous compounds that are non-halogen type is rising. When producing functional film, the physical and thermal properties become distinctly different depending on the amount of Red-phosphorus(RP) addition which causes flame resistance. The physical properties of resin fall in big scale when too much flame retardants are added, and it is hard to be applied to functional films such as shrink or anticorrosive film. The purpose of this research is to study the effects on mechanical, physical, and other properties of RP-LDPE films by changing the RP-MB contents. The LDPE film used for this study was produced through blow-type injection molding. The flame resistance was VTM-0, and the tear resistance showed inverse trends of MD and TD. Contraction percentage showed no relationship with the amount of RP content, but the anti-corrosive property showed 0.05 % better result than the national anti-corrosion shrink film reliability standard.

• KSBB Journal
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• v.17 no.4
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• pp.350-356
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• 2002

Low density polyethylene(LDPE) film was fabricated with the addition of benzoic acid, or/and JP which contained water-soluble silica adsorbed a natural antimicrobial compounds. The used antimicrobial compounds were isolated from culture broths of methylotropic actinomycetes strains MO-16 and MO-17 which was newly isolated from soils. An antimicrobial compound retained antimicrobial activity after heat treatment at 121$^{\circ}C$ for 5 min. JP, which obtained from Japan as a antimicrobial agent, showed antimicrobial activity in the concentration of 100 mg/mL. The silica LDPE film revealed the growth inhibition of total aerobic bacteria in packaged minced pork compared with commercial film and of E. coil on a contained agar plate. In the storage testing of various packaged foods at room temperature for 30 days, the film showed excellent preservation compared with commercial film in case of small tomato and Agaricus bisporus.

• Polymer(Korea)
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• v.28 no.3
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• pp.218-224
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• 2004

The adhesion and proliferation of mammalian cells on polymeric biomaterials depend on the surface characteristics such as wettability, chemistry, charge and roughness. In order to recognize the correlation between the adhesion and proliferation of human bone marrow derived stem cells (BMSCs) and surface property, radio frequency generated plasma treatment on low density polyethylene (LDPE) has been carried out. The modified LDPE surfaces were characterized by measuring the static water contact angle. The adhesion and proliferation of cells on LDPE films were characterized by cell counting and reverse transcription-polymerase chain reaction (RT-PCR). The water contact angle of the film surface decreased with plasma treatment time. Proto-oncogenes (c-myc, c-fos) and tumor suppressor gene (p153) showed maximum expression with contact angle of 60 ∼ 70$^{\circ}$ range of LDPE film. By cell counting, we confirmed that the rate of cell proliferation appeared the higher on the film surface of the contact angle of 60∼70$^{\circ}$ We concluded that the surface wettability is an important role for the growth and differentiation of BMSCs.

• Korean Journal of Medicinal Crop Science
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• v.26 no.4
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• pp.296-301
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• 2018

Background: The objective of this study was to investigate the effect of packaging material on the growth of rootstock of Liriope platyphylla. Methods and Results: This study examined the effects of two types of packaging material, LDPE (low density polyethylene) and functional film on the growth of the tubers of L. platyphylla, at $5^{\circ}C$. During the 16-weeks of storage period, the ratio of loss and decay of the tubers was examined at intervals of 4, 8, and 16 weeks to detect the quality of the plant. After 16 weeks of storage, the treated tubers were own. Subsequently, plant height and the number of leaves were recorded. The results revealed that functional film at $5^{\circ}C$ was the ideal material for the storage of L. platyphylla tubers. The rate of loss was the highest (57.42%) with a onion net and the lowest (22.12%) with a functional film. Similarly, the rate of tuber decay was highest (8.20%) using onion net and the least (4.60%) when the functional film was used. Conclusions: Thus, the use of the functional film proved to be the most effective in the storage of L. platyphylla tubers when compared with the LDPE.

• Proceedings of the KIEE Conference
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• 1998.07d
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• pp.1416-1418
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• 1998

In this paper, the physical and electrical conduction properties due to the electron beam irradiation for low density polyethylene using insulating materials of the distribution cable and ultra-high voltage cable are studied. In FTIR spectrum for physical properties, the strong absorptions by methyl groups in wavenumbers 720[$cm^{-l}$] and 1463[$cm^{-l}$] are observed, and the effect by residual carbonyl groups (C = 0) is hardly appeared. So, as a result of the electrical conduction properties, it is confirmed that the conduction current is increased nearly to 50[$^{\circ}C$], and is not changed until the crystalline melting point from the temperature over 60[$^{\circ}C$] because of the defects of morphology and the formation of many trap centers by means of electron beam irradiation.

• Proceedings of the KIEE Conference
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• 1996.11a
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• pp.193-195
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• 1996

Low-density polyethylene(LDPE ; thickness 100[${\mu}m$] as a experimental specimen is irradiated with electron beam by using electron beam accelerator, and as an experimental specimen, the nonirradiated specimen and the specimen irradiated with electron beam is produced according to the classification of dose. From the analysis of DSC, the crystalline melting point of the specimen irradiated with electron beam is lower than that of virgin specimen. It is confirmed thai the volume resistivity is increased from the temperature over $50[^{\circ}C]{\sim}60[^{\circ}C]$ to the crystalline melting point because of the defects of solid structure and the formation of many trap centers by means of electron beam irradiation, but decreased in the temperature over the crystalline melting point because of the melt of crystalline.