• Journal of Practical Agriculture & Fisheries Research
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• v.20 no.2
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• pp.39-47
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• 2018

This study was carried out to investigate the applicability of alternating temperature control during night time in a nursery seedling production. Three groups of samples were exposed to three different environmental conditions for 6 days from 18:00 to 09:00; one was constantly 15 ℃, another was alternating between 15 ℃ for 2 hours and 11 ℃ for 2 hours, and the other was alternating between 15 ℃ for 2 hours and 11 ℃ for 4 hours. Leaf temperature and stem temperature was measured in real time. The influence of cold stress was analyzed by flavonoid content and growth of tomato seedling. The temperature of leaves and stem became equal to the ambient temperature over time, furthermore, there was no significant difference among the treatments. In conclusion, it is considered that heating costs can be saved considerably, as the alternating temperature has fewer effects on cold stress reaction by tomato seedling growth.

• Journal of Bio-Environment Control
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• v.23 no.2
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• pp.148-157
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• 2014

The purpose of this study was to investigate greenhouse maintenance by farms by looking into greenhouses across the nation for greenhouse specification, disaster-resistance greenhouse construction, types and degree of damage due to natural disasters, pre-inspection in case of typhoon or heavy snow forecast, and fire-fighting facilities to prevent a fire. The findings were summarized as follows: as for greenhouse specification, the highest proportion of them were 90 m or longer both in single- and multi-span greenhouses in terms of length; 8 m or wider and 7.0~7.9 m in single- and multi-span greenhouses, respectively, in terms of width; 1.5~1.9 m and 2.0~2.9 m in single-and multi-span greenhouses, respectively, in terms of height; and 3.0~3.9 m and 6 m in single- and multi-span greenhouses, respectively, in terms of diameter. As for disaster-resistance greenhouses, farmers were reluctant to install such greenhouses. The low distribution of disaster-resistance greenhouses was attributed to the greenhouses built dependent on the old practice, the greenhouses already completed, and relatively high construction costs. As for damage by natural disasters, greenhouses were subject to more damage by typhoons than heavy snow. They mainly inspected the ceiling and side windows, entrances, and fixation bands for covering materials in case of typhoon forecast and the heating devices in case of heavy snow forecast. As for repair methods for greenhouse pipe corrosion, they preferred partial replacement to painting and did not use stiffeners for structures to prevent a natural disaster in most cases. As for the maintenance of greenhouse covering materials, most farmers inspected their sealing property but did not clean the coverings for light transmission. The destruction of structural materials can be prevented by eliminating greenhouse covering materials during a typhoon, but they were not able to do so because of the covering material replacement costs and the crops they were growing. The study also examined whether greenhouse farms had fire-fighting facilities to prevent a fire and found that they lacked the perception of greenhouse fire prevention to a great degree.

• International Journal of Ocean System Engineering
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• v.2 no.3
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• pp.185-194
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• 2012

A Macroscopic combination of two or more distinct materials is commonly referred to as a "Composite Material", having been designed mechanically and chemically superior in function and characteristic than its individual constituent materials. Composite materials are used not only for aerospace and military, but also heavily used in boat/ship building and general composite industries which we are seeing increasingly more. Regardless of the various applications for composite materials, the industry is still limited and requires better fabrication technology and methodology in order to expand and grow. An example of this is that the majority of fabrication facilities nearby still use an antiquated wet lay-up process where fabrication still requires manual hand labor in a 3D environment impeding productivity of composite product design advancement. As an expert in the advanced composites field, I have developed fabrication skills with the use of machinery based on my past composite experience. In autumn 2011, the Korea government confirmed to fund my project. It is the development of a composite sanding machine. I began development of this semi-robotic prototype beginning in 2009. It has possibilities of replacing or augmenting the exhaustive and difficult jobs performed by human hands, such as sanding, grinding, blasting, and polishing in most often, very awkward conditions, and is also will boost productivity, improve surface quality, cut abrasive costs, eliminate vibration injuries, and protect workers from exposure to dust and airborne contamination. Ease of control and operation of the equipment in or outside of the sanding room is a key benefit to end-users. It will prove to be much more economical than normal robotics and minimize errors that commonly occur in factories. The key components and their technologies are a 360 degree rotational shoulder and a wrist that is controlled under PLC controller and joystick manual mode. Development on both of the key modules is complete and are now operational. The Korean government fund boosted my development and I expect to complete full scale development no later than 3rd quarter 2012. Even with the advantages of composite materials, there is still the need to repair or to maintain composite products with a higher level of technology. I have learned many composite repair skills on composite airframe since many composite fabrication skills including repair, requires training for non aerospace applications. The wind energy market is now requiring much larger blades in order to generate more electrical energy for wind farms. One single blade is commonly 50 meters or longer now. When a wind blade becomes damaged from external forces, on-site repair is required on the columns even under strong wind and freezing temperature conditions. In order to correctly obtain polymerization, the repair must be performed on the damaged area within a very limited time. The use of pre-impregnated glass fabric and heating silicone pad and a hot bonder acting precise heating control are surely required.