Research Area

Next-Generation Memory and File System

PRAM memory architecture

According to the improvement of semiconductor techniques, the new class of memory such as PRAM(Phase Change RAM) is ready for wide use. We are catching this new trend of memory area and researching on the new architectures using this new class memory. Main Memory and Storage architectures are our core research interests.

Youngwoo Park, and Kyu Ho Park, "High Performance Scalable Flash File System using Virtual Metadata Storage with Phase-Change RAM" IEEE Transactions on Computers, 2010

SSD : Buffer & FTL Management

SSD is currently becoming a trend of storage. It compromise and replace HDD which was dominant storage hardware before. We are studying the infrastructure of SSD such as SSD Buffer and FTL layer.

Gyudong Shim, YoungWoo Park, Kyu Ho Park, "A Hybrid Flash Translation Layer with Adaptive Merge for SSDs" ACM Transactions on Storage, 2010

File System & Storage System : Performance & Reliability

A RAID is one of the famous storage system for individual and industrial use. The RAID controller or driver has its own cache that is distinguished from the page cache of the host computer. The gray boxes indicate our schemes, contiguity transform for destaging and massive stripe prefetching, adaptive strip prefetching, and strip-aligned sequential prefetching for prefetching and buffer management.

"Independency and Parallelism of Sequential Prefetching in Striped Disk Arrays", Sung Hoon Baek and Kyu Ho Park, IEEE Transactions on Computers 2008
"Prefetching with Adaptive Cache Culling for Striped Disk Arrays", Sung Hoon Baek and Kyu Ho Park, The 2008 USENIX Annual Technical Conference, June 25-27 2008, pp.363-376
"Matrix-Stripe-Cache-Based Contiguity Transform for Fragmented Writes in RAID-5", Sung Hoon Baek and Kyu Ho Park, Transactions on Computers, Vol. 56, No.8, August 2007, pp.1040-1054
"Massive Stripe Cache and Prefetching for Massive File I/O.", Sung Hoon Baek, Kyu Ho Park, IEEE International Conference on Consumer Electronics, pp.5.3-5, Jan, 2007

Cloud Computing

- Cloud-Network/Storage Boost Technology
     Compression-Plugged-Cryptography Technology
- Secure-Metering and Billing Technology

"THEMIS: Towards mutual-verifiable billing transaction for cloud computing environment", K.W. Park, S.K Park, J.S Han, and K. H. Park, Proc. IEEE CLOUD 2010


Human Computer Interaction Research


  Memory contention among consolidated virtual machines (VMs) creates the need for a memory balancing operation. In an attempt to provide a prompt memory balancing mechanism, we found problems with the retardation of memory transfer by the reclamation delay. The scheduling of the VMs generates the delay, and a conflicts of two reclamation policies between the guest OS and the hypervisor deteriorates it. As a remedy to these problems, we propose HyperDealer, which selects the victim page by applying reference patterns, reclaims the pages with hypervisor-level paging, and transfers those pages with ballooning of the guest OS. Our scheme eliminates the involvement of the victim VM in memory balancing and extends the dwell time of reclaimed pages in the reclaimed state. Consequently, HyperDealer significantly reduces the time taken to transfer memory with a low overhead and enhances the value of additional memory for the recipient VM. The experimental results of our scheme show that the application performance in the recipient VM is 11% more time-efficient and has a penalty which is 50% less than previous approaches.

Sensor Network

A Multi-Channel Grouping for Reducing Latency in Wireless Sensor Networks
Energy Efficient Cross-Layer Aggregation Protocol in Wireless Sensor Networks
Hierarchical Cluster-based Multi-hop Scheduling (HCMS) for wireless sensor networks