• Journal of the Korea Society of Computer and Information
• /
• v.25 no.2
• /
• pp.1-10
• /
• 2020

In this paper, we propose an efficient disk buffer replacement policy which improves hit ratio and reduces writing operations of flash based storages. The flash based storage has many advantages, including a small form factor, non-volatility and high reliability, but there are problems caused by own limitations, like not-in-place update, short life cycle and asymmetric I/O latencies. To redeem these problems, this paper proposes the write weighted probability of reference(2WPR) policy. 2WPR policy predicts re-referencing probability and calculates localities of each page. Furthermore, by weighting write operations to every pages, 2WPR can reduce write operations to flash based storage. In addition, we can improve the performance with higher hit ratio and reduce the number of write operations and consequently shorten the latencies of each operation. The results show that our policy provides improvements of up to 10% for the hit ratio with the reduction of up to 5% for the flash writing operation compared with other policies.

• Environmental and Resource Economics Review
• /
• v.13 no.2
• /
• pp.271-300
• /
• 2004

We investigate the two recent simulations of the proto-type domestic carbon emission trading system in Korea and draw some policy implications. The first simulation includes the 5 electric power companies based on baseline and credit. But the second one is with the 7 energy-intensive companies based on cap and trade. The voluntary approaches in this paper revealed the instability of market equilibrium, i.e., price volatility or distortion, excess supply or demand. These phenomena stems from excess incentives to the players, asymmetric information, players' irresponsible strategic behaviors, and non acquaintance of trading system. This paper suggests the basic design for domestic carbon trading system in future and a stepwise introduction strategy for it including the incentive auction scheme, the total quantity of incentive needed, and how to finance it. Meantime, the further simulations on the various sectors based on voluntary participation must be essential for learning experiences and better policy design.