대부분의 웹 캐시는 도큐먼트를 기반으로 하여 캐시 내에 임시적으로 도큐먼트를 저장하고 사용자의 요청이 있을 때 그에 해당된 도큐먼트가 캐시 내에 존재하면 그 도큐먼트를 사용자에게 전송해 주고, 캐시 내에 존재하지 않을 때에는 새로운 도큐먼트를 서버에게 요청하여 캐시 내에 복사를 하고 사용자에게 되돌려 준다. 이때 캐시의 용량 초과로 인해 새로운 도큐먼트를 기존의 도큐먼트와 교체하기 위해 도큐먼트 교체정책(replacement policy)을 사용한다. 일반적인 교체정책에는 도큐먼트를 기반으로 한 LRU기법이나 UFU기법 등이 있고, 그 밖의 여러 가지 교체정책을 사용하여 캐시내의 도큐먼트를 효과적으로 교체한다. 하지만, 위의 교체정책은 사이트의 인기도를 고려하지 않고 도큐먼트 요청 시간과 빈도수 만을 고려하여 교체정책을 수행한다. 따라서 본 논문에서는 요청이 빈번한 도큐먼트와 사이트의 인기도를 고려한 교체정책을 사용하여 요청이 빈번하지 않은 도큐먼트를 효과적으로 교체함으로써 캐시의 적중률(hit-ratio)을 높이고, 캐시의 내용을 효과적으로 관리할 수 있는 현대적인 네트워크 환경에 적합한 도큐먼트 교체정책인 사이트의 인기도를 고려한 도큐먼트 교체 정책을 제시한다.

Since legislation of Rural Minor Road Improvement Act 1990, a quarter of its total length had been paved now. However, over 80% of arterial road length(national+provincial roads) had been paved, so, road improvement policy should be focussed on the local road(county+rural minor roads) from now. Generally, in the greater part of coastal plain and island areas, arterial road intensity(total road length/total catchment area) is relatively low, but local road intensity is relatively high. So, in terms of balanced development, much more efforts for rural minor road improvement should be concentrated in coastal plain and islands areas. In Chonnam Province, the maximum differentials of minor rural road improvement ratio was over 20%(the lowest; 14.1% in Goheung, the highest; 35.6% in Goksung) in 1999, but the improvement budget have been allocated in proportion to unpaved road length of each county by the provincial government. However, the differentials should not be fairly narrowed in the near future if the present budget allocation policy be maintained. To solve this problem, target differentials of rural minor road improvement between regions should be set up for each planning year and road improvement budget be allocated according to this policy change.

The conflicts between environment protection and economic development are becoming increasingly important in environmental decision making of Nakdong River Basin. A science-based evaluation system is now needed to represent both the environmental values and the economic values with a common measure. EMERGY, spelled with an "m" evaluates both the work of river and that of human in generating products and services. The monetary cost-benefit analysis and the environmental accounting by EMERGY analysis were applied to determine whether there will have a net benefit in environmental decision making of Nakdong River Basin. Based on the results of the environmental accounting, all alternatives which related to environmental decision making of Nakdong River Basin show that more and more of EMERGY cost becomes needed than the EMERGY benefit from getting water to drink in the lower basin. From these results, for selecting alternatives to manage water quantity and quality that is sustainable in the environmental use and economic development, environmental accounting concepts must be considered, and the economic structure of Nakdong River Basin should be changed from the present industrial structure to social-economic structure based on ecological-recycling concept for the sustainable use of Nakdong River.

In this study, a model was developed to analyze the capacity and the total price of the agricultural products marketing between nations through the estimation of the production and consumption amount of the agricultural products in each nation and the analysis of the price and transport cost to each nation. The method which can contribute to the agricultural policy decision support was devised. The main concept of the method is to compute the potential import-export amount and total cost among the nations. In the application, wheat was selected to evaluate the model. The application results showed that the model could analyzed the unit consumption and storage amount per capital of each nation and the price and transport cost per unit weight from each export nation, provided the policy decision maker with the basic data analyzed by GIS.