Yeats and Keats differently introduced their notions of time circulation and eternal life. One expressed limitations of human which could be overcome by art. And the other introduced time flowing in harmony and peace. And in one poem, we can see something lively such as young people, birds, trees, salmon-falls, and in the other poem we can find laziness and leisure. However, there is some similarity in that they introduce the subjects of circulation of life and eternal life. Yeats shows the passage of time by the Great Wheel or gyre which develops in the course of formation, fullness, decline. And Keats also presents the passage of time by using the phrases such as “swell the gourd,” “plum the hazel shell,” “warm day will never cease.” These symbolize swelling and continuance of time. So we can find the way how time is flowing in their poems. In Yeats's “Sailing to Byzantium,” time travels from a youth to an old age, and in “To Autumn,” time travels from summer to autumn. In this circulation Yeats's immortality can be reached by the media of art. And Keats gets it by the circulation of seasons. So one continues to voyage with eagerness for Byzantium in which he could find his everlasting life through the mosaic of 15th century, and the other comfortably waits for next seasons. Two poets respectively develop their poems in different ways, but they finally achieve the same subjects of ever-lasting life in the passage of time. In conclusion, Yeats pursued immortality by separating spirit from the body, because the flesh would be decayed. On the other hand, Keats thought that the immortality could be acquired by being one with time. Unlike Yeats's “Sailing to Byzantium”, Keats's “To Autumn” has a tendency to keep harmony and reconciliation, instead of confrontation. Therefore, autumn enjoys “sitting,” and “asleep” without haste.

For the purpose of evaluating the eco-efficiency(EE) on surplus heat generated from industrial process, techniques of life cycle assessment are adopted in this study. Because it can be indicated both environmental impacts and economic benefits, EE is well known as a useful tool for symbiosis network on the sustainable development of new projects and businesses. To evaluate environmental impacts, the categories were divided into two areas of resource depletion and global warming potential. It can be seen that environmental impact increased a little but much higher economic benefit on the company, environmental performance and economic value were improved on the apartment by the district heating, respectively. In result, eco-industrial park(EIP) project on surplus heat should be found sustainable new business because the EE was in the area of fully positively eco-efficiency and, moreover resource depletion was taken place than the reduction of greenhouse gas.