• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.8
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• pp.23-28
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• 2019

The structural integrity of a surface metal coating was evaluated through numerical results to improve the efficiency and reduce the damage caused by cavitation in ships and marine plants. The goal was to ensure structural strength and performance, even if the thickness of the wing is reduced to reduce the weight of the material and surface coating. Analytical methods were used for four models: a non-coating model, one with the same thickness after coating, one with a thickness reduction of 3% after coating, and one with thickness reduction of 5% after coating. With a thickness reduction of 5% after coating, the stress was increased to 12%, and the safety factor was 0.99%, so the structural integrity was insufficient. However, a better material or a thicker coating could allow a sufficient safety factor to be secured. The structural integrity was improved by the coating, and even when the weight was reduced up to 5%, the structural integrity could be sufficiently secured due to the coating effect.

• Korean Journal of Environment and Ecology
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• v.25 no.5
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• pp.649-657
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• 2011

This study had targeted the Manjong Junction~Hongchun interchange section of Jungang highway in order to analyze the efficiency and improvement of the highway wild-life fences. Being analyzed wild-life fence as an effective facility for the prevention of road-kill, it had founded that the wild animals did not jump over even the two layer guardrail, concrete barrier and noise barrier, fence for rock fall. For the section with high road-kill decrease effect after installing the wild-life fence, the effect was higher at wild-life fence with the height of 1.0m where the door had not been installed and the well connected points of road facility than the area with fence height of 1.5m. The road-kill decrease effect was also high at the well managed areas even if the door has not been installed. Also, road-kill had occurred by concentrating around the end of wild-life fence after installing the fence, Moreover road-kill had also occurred around the cutting section. The door of wild-life fence had higher amount of road-kill occurrence as the installation interval was closer. it was analyzed that the door management has a lot of effect on road-kill decrease. The fence for rock fall, two layer guardrail and concrete barrier having the effect of wild-life fence installed on the road would have to be installed by connecting with wild-life fences through proper facility improvement. Although the door should not be installed if possible, it should be installed as automatic door or gravity door to prevent the door from leaving the door open. An escape route has to be formed for the prompt escape away from the road for the animals entered through the ending section of the fence. The eco-corridor has to be made by restoring the soil layer of dual purpose eco-corridor forming a planting area. Also, the dead body after the accident has to be disposed to the outer section of the road immediately in order to prevent the secondary road-kill by the predator from the road-kill. The fence has to be installed as 500m or longer in both ways, in other words 1,000m or longer, from the targeted spot of minimum accident prevention while connecting up to the bridge or box culvert, etc that are next road facilities if possible to guide wild animals safely to the eco-corridor.

• Korean Journal of Agricultural and Forest Meteorology
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• v.16 no.4
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• pp.285-296
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• 2014

The impacts of high temperature and drought were studied on the seedlings of three families (superiorgangwon74, intermediate-gangwon77 and inferior-gangwon132) of P. densiflora which had been selected by the based on the growth indexes of 32-year-old. The seedlings were grown in controlled-environment growth chambers with combinations of four temperatures ($-3^{\circ}C$, $0^{\circ}C$, $+3^{\circ}C$ $+6^{\circ}C$; based on the monthly average for 30 years in Korea) and two water conditions (control, drought). The growth performance, photosynthetic parameters and photosynthetic pigment contents were measured at every 30 days under four temperatures and drought condition, and the end of each treatment. The superior family showed higher relative diameter at root collar growth rate and the dry weight than intermediate and inferior family in all treatments. Under elevated temperature and drought condition, growth rate was decreased, and seedlings showed lower growth rate than that of control in three families under low temperature. Photosynthetic rate, stomatal conductance and transpiration rate of three families decreased with the increase of temperature and drought condition, and that of seedlings under low temperature was lower than control. But under elevated temperature and drought condition, water use efficiency increased in three families. Photosynthetic pigment contents of leaves decreased under the increase of temperature and drought condition, but chlorophyll a/b ratio increased with the increase of temperature and drought condition in three families. The superior family showed higher total chlorophyll content than intermediate and inferior family in all treatments. In conclusion, P. densiflora is under changed temperature and drought condition, growth was decreased, seedlings more affected in elevated temperature than that of decreased temperature. The increase in monthly average temperature in Korea of more than $6^{\circ}C$, P. densiflora seedling growth in depending on region may decrease. In this study, the superior family(gangwon74) showed more excellent growth and physiological responses than intermediate (gangwon77) and inferior(gangwon132) family under changes temperature and drought.

• Korean Journal of Agricultural and Forest Meteorology
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• v.22 no.1
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• pp.26-46
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• 2020

An irrigated-maize agroecosystem is viewed as an open thermodynamic system upon which solar radiation impresses a large gradient that moves the system away from equilibrium. Following the imperative of the second law of thermodynamics, such agroecosystem resists and reduces the externally applied gradient by using all means of this nature-human coupled system acting together as a nonequilibrium dissipative process. The ultimate purpose of our study is to test this hypothesis by examining the energetics of agroecosystem growth and development. As a first step toward this test, we employed the eddy covariance flux data from 2003 to 2014 at the AmeriFlux NE1 irrigated-maize site at Mead, Nebraska, USA, and analyzed the energetics of this agroecosystem by scrutinizing its radiation, energy and entropy exchange. Our results showed: (1) more energy capture during growing season than non-growing season, and increasing energy capture through growing season until senescence; (2) more energy flow activity within and through the system, providing greater potential for degradation; (3) higher efficiency in terms of carbon uptake and water use through growing season until senescence; and (4) the resulting energy degradation occurred at the expense of increasing net entropy accumulation within the system as well as net entropy transfer out to the surrounding environment. Under the drought conditions in 2012, the increased entropy production within the system was accompanied by the enhanced entropy transfer out of the system, resulting in insignificant net entropy change. Drought mitigation with more frequent irrigation shifted the main route of entropy transfer from sensible to latent heat fluxes, yielding the production and carbon uptake exceeding the 12-year mean values at the cost of less efficient use of water and light.