Among the various kinds of jewels, emerald especially fascinates me. Because in my opinion emerald not only has been treasured as a jewel for a long time, but also has had various influences on man's history and culture.
Consideration of Japanese sustainable clean-water supply system
Human has been trying to secure water for a long time in terms of human history. Baoli is an example of the human attempt in India. However, with regard to modern Japan which has many overpopulated areas, the problem how we secure clean water is more important. From this point of view, the present Japanese clean-water supply system will be faced with some difficult problems. Therefore, it can be said that we need to int..