The rapid technology development in digital networks and telecommunications has a significant effect on the contemporary analysis of cities in the world, To dates cities are increasingly becoming infused with a wide range of new telecommunications, networks and infrastructures. A new and novel concept of 'U-City' to urban and regional planning has been adopted in the Republic of Korea that allow new forms of urban development. which often encumbered with its proponents to resolve chronic urban problems for a sustainable development. This is partially attributed to the fact that a philosophy, vision and demand for ubiquitous technologies and cities remain immature and sometime inadequately focused. Despite a groundswell of the technology-oriented approach to a digital city development, there is a lack of discussion of U-City's philosophy how U-City could contribute to a human-oriented and environmentally sound sustainable development and its vision how U-City is moving forward, and demand how U-City is actually involved in meeting specific urban needs. Arguably, while U-City could led to a mega-trend of urban development by decreasing the trip distance, and energy and land consumption, and the spread of this practice which helps in environmentally sound sustainable development for the future, ubiquitous computing technologies could be harmful if misused such as well-known problems of loss of confidentiality and privacy breech of personal tracking and security systems. It is within the context of philosophy, vision and demand of U-City that this paper heavily stresses.