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Kwack Y.,Research Institute of Agriculture and Life science | Chun C.H.,Research Institute of Agriculture and Life science | Chun C.H.,Seoul National University
Korean Journal of Horticultural Science and Technology | Year: 2015

Cucumber and paprika transplants were stored at 9, 12, 15, and 18°C under dark conditions for 15 days and then grown in a greenhouse for 14 days after transplanting. To determine the effects of low storage temperature and long-term continuous darkness on the quality and vigour of transplants, we investigated the quality of transplants during storage and the growth of stored transplants after transplanting. In cucumber transplants, decreasing storage temperature reduced stem elongation and decrease in SPAD value. The quality of cucumber transplants stored at 9°C was well preserved during storage, but they did not survive after transplanting due to chilling damage. Growth and development after transplanting were significantly greater when cucumber transplants were stored at 12°C. In paprika transplants, the quality of transplants did not significantly differ before and after storage. After transplanting, there was no significant difference in the survival rate and growth, but the number of flower buds was greater in the paprika transplants stored at lower temperatures (9 and 12°C). These results indicate that the responses of transplants to the conditions of low temperature and darkness differed between cucumber and paprika, and storage temperature in darkness must be controlled carefully considering species-specific responses to reduce quality deterioration during storage and improve the recovery of transplants after transplanting. © 2015 Korean Society for Horticultural Science.

Park C.-H.,Seoul National University | Lee S.-J.,Seoul National University | Lee T.-H.,Seoul National University | Kim H.-J.,Seoul National University | Kim H.-J.,Research Institute of Agriculture and Life science
Reactive and Functional Polymers | Year: 2016

Optically clear adhesive (OCA) is a key material for assembling a touch screen panels (TSP). TSPs are now applied to many devices; therefore, their preparation and adhesion performance examination including durability can be beneficial work. Cloud point resistance means that a material does not have a hazy appearance under any environment, especially under sudden temperature and humidity changes. It is a critical property for an OCA because it is directly related to image display on a TSP. A hydrophilic component needs to be incorporated to the OCA, and 2-hydroxyethyl acrylate (HEA) was selected as the monomeric hydrophilic component. The change in adhesion performance under hygrothermal aging conditions was investigated. The aging behavior was also monitored using infrared (IR) and Raman spectra and chemiluminescence (CL) analysis. The HEA-containing pressure-sensitive adhesive (PSA) exhibited a good cloud point resistance and adhesion performance along with stable adhesion properties during aging. This consequence is considered suitable behavior for the prepared PSA as an OCA. © 2016 Elsevier B.V. All rights reserved.

Park C.-H.,Seoul National University | Lee S.-J.,Seoul National University | Lee T.-H.,Seoul National University | Kim H.-J.,Seoul National University | Kim H.-J.,Research Institute of Agriculture and Life science
International Journal of Adhesion and Adhesives | Year: 2015

Optically clear adhesives (OCAs) are key components of touch screen panels (TSPs). It is important that OCAs do not affect the transparent electrodes in TSPs because OCAs are contacted to the transparent electrodes. Therefore, N-vinyl caprolactam (NVC) was incorporated in the composition of an acrylic pressure sensitive adhesive (PSA) with excluding an acidic component to maintain the cohesion for OCA preparation. With increasing amounts of NVC, the tack and peel strength of UV-cured PSA increased, but high amounts of NVC led to decreased peel strength. The UV-cured PSA films were placed in a high temperature and humidity chamber for 8 weeks to investigate the durability and corrosion property under hygrothermal conditions. In this study, the corrosion test method using copper foil was suggested as a simple and economical method and was used to evaluate the effect of NVC on the corrosion property of PSA. This method helped identify suitable OCAs that do not have corrosive property. PSA films containing more than 20 wt% of NVC promoted the corrosion of copper foil under hygrothermal aging conditions. The caprolactam ring was opened by moisture, and the PSA structure morphed into a polar structure during the aging process. This change caused a glass transition shift, an increase in the storage modulus at the rubbery plateau, and an increase in peel strength. The surface free energy of the PSA films also increased due to the increase in the polar property. However, high amounts of NVC caused a decrease in the peel strength after 8 weeks of aging because of increased molecular interactions. © 2015 Elsevier Ltd. All rights reserved.

Jeong E.,Seoul National University | Shin S.,Seoul National University | Park M.,Seoul National University | Hyun J.,Seoul National University | Hyun J.,Research Institute of Agriculture and Life science
Palpu Chongi Gisul/Journal of Korea Technical Association of the Pulp and Paper Industry | Year: 2015

Natural cellulose hydrogel membrane cannot be directly used for cell encapsulation because it has many large pores on the surface that immune biomolecules are able to penetrate into easily. For the reason, alginate was used for the control of pore size of the cellulose hydrogel membrane. The surface morphology of cellulose/alginate nanocomposite confirmed the successful control of the porosity of the membrane. The permeability of the cellulose/alginate nanocomposite was decreased but mechanical properties were increased compared with the bacterial cellulose membrane. The cellulose/alginate nanocomposite could be used for the functional membrane as a promising biomedical material in the future.

Ha T.,Seoul National University | Lee I.-B.,Seoul National University | Lee I.-B.,Research Institute of Agriculture and Life science | Kwon K.-S.,Seoul National University | Hong S.-W.,Belgium Institute for Agricultural and Fisheries Research
International Journal of Agricultural and Biological Engineering | Year: 2015

Abstract: Greenhouse Building Energy Simulation (BES) models were developed to estimate the energy load using TRNSYS (ver. 16, University of Wisconsin, USA), a commercial BES program. Validation was conducted based on data recorded during field experiments. The BES greenhouse modeling is reliable, as validation showed 5.2% and 5.5% compared with two field experiments, respectively. As the next step, the heating characteristics of the greenhouses were analyzed to predict the maximum and annual total heating loads based on the greenhouse types and target locations in the Republic of Korea using the validated greenhouse model. The BES-computed results indicated that the annual heating load was greatly affected by the local climate conditions of the target region. The annual heating load of greenhouses located in Chuncheon, the northernmost region, was 44.6% higher than greenhouses in Jeju, the southernmost area among the studied regions. The regression models for prediction of maximum heating load of Venlo type greenhouse and widespan type greenhouse were developed based on the BES computed results to easily predict maximum heating load at field and they explained nearly 95% and 80 % of the variance in the data set used, respectively, with the predictor variables. Then a BES model of geothermal energy system was additionally designed and incorporated into the BES greenhouse model. The feasibility of the geothermal energy system for greenhouse was estimated through economic analysis. © 2015, Int J Agric & Biol Eng. All rights reserved.

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