• Fibers and Polymers
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• v.5 no.4
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• pp.289-296
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• 2004

The kinetic parameters, including the activation energy E, the reaction order n, and the pre-exponential factor Z, of the degradation of the copolymers based on the poly(L-lactide) (PLLA) or poly(p-dioxanone-co-L-lactide) (PDO/PLLA) and diol-terminated poly(ethylene glycol) (PEG) segments have been evaluated by the single heating methods of Friedman and Freeman-Carroll. The experimental results showed that copolymers exhibited two degradation steps under nitrogen that can be ascribed to PLLA or PDO/PLLA and PEG segments, respectively. However, copolymers exhibited almost single degradation step in air. Although the values of initial decomposition temperature were scattered, copolymers showed the lower maximum weight loss rate and degradation-activation energy in air than in nitrogen whereas the higher value of temperature at the maximum rate of weight loss was observed in air.

• Proceedings of the Korean Society of Postharvest Science and Technology of Agricultural Products Conference
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• 2004.10a
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• pp.67-72
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• 2004

Quality of fresh-cut tomato slices was compared during cold storage under various modified atmosphere packaging conditions. Chilling injury of slices in containers sealed with Film A was higher than with Film B; these films had oxygen transmission rates of 87.4 and 60.0 ml $h^{-1}\;m^{-2}\;atm^{-1}$ at $5^{\circ}C\;and\;99\%$ RH, respectively. While slices in containers with an initial atmospheric composition of air, $4\%\;CO_2+1\;or\;20\%\;O_2,\;8\%\;CO_2+1\;or\;20\%\;O_2,\;or\;12\%\;CO_2+20\%\;O_2$ showed fungal growth, slices in containers with $12\%\;CO_2+1\%\;O_2$ did not. Low ethylene in containers enhanced chilling injury. Modified atmosphere packaging provided good quality tomato slices with a shelf-life of 2 weeks or more at $5^{\circ}C$. Experiments were conducted to compare changes in quality of slices of red tomato (Lycopersicon esculentum Mill. 'Sunbeam') fruit from plants grown using black polyethylene or hairy vetch mulches under various foliar disease management systems including: no fungicide applications (NF), a disease forecasting model (Tom-Cast), and weekly fungicide applications (WF), during storage at $5^{\circ}C$ under a modified atmosphere. Slices were analyzed for firmness, soluble solids content (SSC), titratable acidity (TA), pH, electrolyte leakage, fungi, yeasts, and chilling injury. With both NF and Tom-Cast fungicide treatments, slices from tomato fruit grown with hairy vetch (Vicia villosa Roth) mulch were firmer than those from tomato fruit grown with black polyethylene mulch after 12 days storage. Ethylene production of slices from fruit grown using hairy vetch mulch under Tom-Cast was about 1.5- and 5-fold higher than that of slices from WF and NF fungicide treatments after 12 days, respectively. The percentage of water-soaked areas (chilling injury) for slices from tomato fruit grown using black polyethylene mulch under NF was over 7-fold that of slices from tomato fruit grown using hairy vetch under Tom-Cast. When stored at $20^{\circ}C$, slices from light-red tomato fruit grown with black polyethylene or hairy vetch mulches both showed a rapid increase in electrolyte leakage beginning 6 hours after slicing. However, slices from tomato fruit grown using the hairy vetch mulch tended to have lower electrolyte leakage than those grown with black polyethylene mulch. These results suggest that tomato fruit from plants grown using hairy vetch mulch may be more suitable for fresh-cut slices than those grown using black polyethylene mulch. Also, use of the disease forecasting model Tom-Cast, which can result in lower fungicide application than is currently used commercially, resulted in high quality fruit for fresh-cut processing. Experiments were conducted to determine if ethylene influences chilling injury, as measured by percentage of slices exhibiting water-soaked areas in fresh-cut tomato slices of 'Mountain Pride' and 'Sunbeam' tomato (Lycopersicon esculentum Mill.). Ethylene concentration in containers without ventilation significantly increased during storage at $5^{\circ}C$, whereas little or no accumulation of ethylene occurred in containers with one or six perforations. Chilling injury was greatest for slices in containers with six perforations, compared to slices in containers with one perforation, and was over 13-fold greater than that of slices in control containers with no perforations. An experiment was also performed to investigate the effectiveness of including an ethylene absorbent pad in containers on subsequent ethylene accumulation and chilling injury. While ethylene in the no-pad controls increased continually during storage of both 'Mountain Pride' and 'Sunbeam' tomatoes at $5^{\circ}C$ under modified atmosphere conditions, no increase in accumulation of ethylene was observed in containers containing ethylene absorbent pads throughout storage. The ethylene absorbent pad treatment resulted in a significantly higher percentage of chilling injury compared with the no-pad control. In studies aimed at inhibiting ethylene production using AVG during storage of slices, the concentration of ethylene in control containers (no AVG) remained at elevated levels throughout storage, compared to containers with slices treated with AVG. Chilling injury in slices treated with AVG was 5-fold greater than that of controls. Further, we tested the effect of ethylene pretreatment of slices on subsequent slice shelf-life and quality. In slices treated with ethylene (0, 0.1, 1, or $10\;{mu}L\;L^{-1}$) immediately after slicing, ethylene production in non-treated controls was greater than that of all other ethylene pre-treatments. However, pretreatment of slices 3 days after slicing resulted in a different pattern of ethylene production during storage. Ihe rate of ethylene production by slices treated with 1 L $L^{-1}$ ethylene 3 days after slicing was greater during storage than any of the other ethylene treatments. With slices pre-treated with ethylene, both immediately and 3 days after slicing, the rate of ethylene production tended to show an negative correlation with chilling injury. Chemical name used: 1-aminoethoxyvinylglycine (AVG).

• Macromolecular Research
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• v.12 no.5
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• pp.443-450
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• 2004

We have studied the effects that inorganic zeolite powder have on structurally different copolymer [poly(propylene-co-ethylene)] and terpolymer [poly(propylene-co-ethylene-co-l-butene)] systems and the possibility of preparing suitable porous composite films. The impact strength and yield stress of the composites did not improve upon any further loading of zeolite, but the modulus increased gradually with respect to the filler loading. The experimental modulus of each of the two systems was compared with theoretical models. We performed a morphological study of the filler mixing efficiency and image analysis. The number-, weight-, and z-average air hole diameters were compared with respect to the draw ratio as well as the zeolite loading. The experimental results suggest that these two matrices can provide a new choice for preparing future multiphase polymeric porous films by stretching them unidirectionally. In particular, we suggest that a 40 wt% zeolite loading at a draw ratio of 4 is useful for porous film applications.

• Journal of Climate Change Research
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• v.9 no.1
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• pp.69-74
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• 2018

The purpose of this study is to suggest the methodology of $CO_2$ Emission Factor Verification and Quantitative Assessment in Ethylene Product Processes. At first, this study compare the IPCC (Intergovernmental Panel on Climate Change) 1996 Guideline and 2006 Guideline. And analyse methodology for estimating $CO_2$ emission and $CO_2$ emission factor in Ethylene product process. Also analyse cases of estimating $CO_2$ emission factor based on material balance. Methodology of $CO_2$ Emission Factor Verification and Quantitative Assessment are following the categories proposed by GIR (Greenhouse Gas Inventory and Research Center). There are total 12 factors in 8 categories and give 5 or 10 points according to their importance. Also this study suggests necessary data of document to meet the conditions. The result would help estimate accuracy Greenhouse Gas Inventory. Also contribute to establish policy on environmental assessment, air conservation, etc.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.17 no.4 s.121
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• pp.342-349
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• 2007

Following the 2002 World-Cup held in Korea, studies have been actively conducted on plans to utilize all-weather stadiums of fine figures, where large-scale spaces are available for various utilizations. In Japan, dome-type stadiums have been built and are utilizing across the whole nation not only for sports events but also variety of other large-scale events. PTFE(poly tetra fluoro ethylene) is one of the membrane material mainly used for the outer ceiling surface of membrane structures. However, there has not been enough research on the acoustical properties of PTFE membrane material which has been widely used in the multi-purpose stadiums. In this study, air permeability values and sound absorption coefficient of PTFE membrane materials were measured and evaluated in the gymnasium. From the results of measurements of sound absorption coefficient and air permeability of inner membrane materials, it was found that the sound absorption coefficient was good in the air permeability range of $5{\sim}15\;cc/cm^2/s$. Also the relation ship between air permeability and sound absorption coefficient was very high and the sound absorption coefficient was the highest in the range of $6{\sim}9\;cc/cm^2/s$. Secondly, an analysis on the measurements sound absorption characteristics of inner membrane material reveals that the overall sound absorption coefficient was stabilized(higher than 0.5 throughout the whole frequency bands) when the air space behind the membrane material was deeper than 600 mm. When PTFE sound absorptive membrane material was installed in the ceiling of gymnasium, it was confirmed that sound absorptive membrane material can reduce reverberation and increase speech intelligibility in the gymnasium.

• Journal of Korean Society of Forest Science
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• v.103 no.3
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• pp.368-374
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• 2014

This study was investigated the changes of storability and quality characteristics of 'Autumn Sense' hardy kiwifruit according to ethylene treatment and storage condition. In the results of investigation of changes in hardy kiwifruit quality during storage period, hardness of ethylene treated hardy kiwifruit during 48 and 96 hours was rapidly decreased, but soluble solid content was rapidly increased with the passing of storage period in all treatment groups. The total acid was estimated from 0.7 to 1.4% with storage period in all treatment groups. In the results of investigation of the weight loss rate, ethylene treated hardy kiwifruit during 48 hours was the highest 30.9% in storage at $20^{\circ}C$ and lowest 5.9% in storage at $2^{\circ}C$ with a relative air humidity of about 90% during storage at 24 days. Ethylene treated hardy kiwifruit during 96 hours was decrease 29.4% in storage at $20^{\circ}C$, 20.7% in storage at $4^{\circ}C$, 12.1% in storage at $2^{\circ}C$, and 6.0% in storage at $2^{\circ}C$ with a relative air humidity of about 90% during storage at 22 days. The taste of hardy kiwifruit during storage was reduced to increase in all treatment groups. Particularly, storage at $20^{\circ}C$ was rapidly reduced to increase in the early storage and storage at $2^{\circ}C$ with a relative air humidity of about 90% was decrease after storage at 18 days. The rotten rate during storage was increased in all treatment groups, storage at $20^{\circ}C$ was after storage at 2 days and storage at $2^{\circ}C$ with a relative air humidity of about 90% was rapidly increased after storage at 16 days. Thus, it can be recommended that storage at $2^{\circ}C$ with a relative air humidity of about 90% is good to maintain quality. Also, we will decide optimal storage condition and after-ripening time of 'Autumn Sense' hardy kiwifruit.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.7
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• pp.265-271
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• 2019

The aim of this paper was to improve the shortcomings of Pitcher Concrete, a conventional ethylene-based polymer used in combination with the other components, and present basic data for use as improved road pavement material by applying an acrylic polymer. Existing ethylene polymer-based pitcher concrete materials were selected. Acrylic polymer was then added and the resulting mixture was evaluated. The compressive strength of the existing ethylene-based polymer pitcher concrete combination was low due to the large air gap, and a compressive strength of 24MPa was observed on the 28th day of road use, as defined by KS for an acrylic polymer-based pitcher concrete combination. Regarding the bending strength, the combined strength of the acrylic polymer-based pitcher concrete was excellent, and the factor of the pitcher was measured above the reference, 0.1(mm/s), in all variables. All parameters measured were less than 1%. The acrylic polymer mixing characteristics were able to maintain the dynamic modulus of elasticity for more than 120 cycles, but not more than 80 cycles for the other combinations. Therefore, the addition of more acrylic polymer than conventional ethylene polymer base is effective in improving the durability.

• Membrane Journal
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• v.27 no.4
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• pp.336-343
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• 2017

These days, the quality of indoor air is a very important concept for modern people who have lived in building and is a matter of new thinking. The quality is determined by the temperature and humidity of indoor air. In addition, there is a disadvantage in that energy consumption is severe for indoor air improvement. Therefore, researches on methods to solve such problems using total heat exchange have been actively conducted. So, in this study, aminated poly(styrene-ethylene-butylene-styrene) polymers were synthesized by introducing a hydrophilic substituent, ammonium, into main chain and the properties of synthesized polymers were evaluated. The synthesis was carried out through chloromethylation and amination reactions to introduce ammonium into main chain. As a result, the water uptake and the ion exchange capacity of the synthesized polymers increased as the content of the reaction reagent solution increased. It was confirmed that the important data at the total heat exchange membrane, water vapor transmission rate also increased according to temperature, equivalent.

• Horticultural Science & Technology
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• v.32 no.2
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• pp.178-183
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• 2014

This study aimed to evaluate the fruit quality characteristics and incidence of flesh browning in response to air storage at $0{\pm}1^{\circ}C$ a fter controlled atmosphere s torage (CA condition: $O_2$ $2.5{\pm}0.5$%, $CO_2$ $1.5{\pm}0.5$%) at $0{\pm}1^{\circ}C$ in 'Fuji' apples (Malus domestica Borkh.). The storage system was performed as followed: air storage for one month, CA storage 4 months + air storage 3 months ( CA 4M + A ir 3M), CA storage 5 m onths + air storage 2 months ( CA 5M + Air 2M) a nd C A storage 6 m onths + air storage 1months (CA 6M + Air 1M), while the control fruits were stored at CA storage for 8 months right after harvest. The incidence of flesh browning ranged from 17.1% to 30.2% during CA storage but not detected under the treatments of CA 4M + Air 3M and CA 5M + Air 2M. The respiration rate was not affected by storage treatments for 6M while the respiration rate was lower in the treatments of CA 4M + Air 3M and CA 5M + Air 2M than the other storage treatments after 7 months. Ethylene production and internal ethylene concentration were lowest in rapid CA storage and increased with a decreasing CA storage duration. Therefore, the results indicate that CA 5M + Air 2M storage treatment should be recommended to maintain the fruit quality and reduce the risk development of flesh browning rather than typical CA storage in 'Fuji' apples.

• Resources Recycling
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• v.11 no.1
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• pp.37-42
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• 2002

This study was conducted in order to remove Poly vinyl chloride(PVC) from the waste plastic film mixture. The fittings of Air Table was modified to increase the separation efficiency of PVC and PE(poly ethylene). PE and PVC was successfully separated from PVC-PE film mixture with the yield of PE 90% or more and with his grade of 99% or more, using the improved Air Table. The details of the separation condition and results will be discussed in this paper. Dry separation, Waste plastic film, PVC, Air Table. The details of the separation condition and results will be discussed in this paper.