• Sangwook Shane Hahn ('18 Ph.D)

  Ph.D. Student
  shanehahn@davinci.snu.ac.kr
  
  - Gold Prize in Computer Science & Engineering, Samsung Humantech Paper Award, 2014
  - Best Paper Award in Mobile Application and System, Korea Computer Congress, 2016
  - Ph.D. Fellowship - Naver Corporation, 2016
  - Honorable Mention in Computer Science & Engineering,  Samsung Humantech Paper Award, 2017
  - Student Grants USENIX FAST 2014, USENIX OSDI 2014, USENIX FAST 2016, ACM SIGOPS APSys 2017, Flash Memory Summit 2018
  - Best Researcher Award - BK21PLUS Research Program
  

I/O Performance Analysis and Optimizations for Smart phones

• NAND flash management software
• Storage system solution
• Cross-layer optimization
• Linux kernel optimization (Storage I/O stack)
• ARM architecture-based embedded system
• Android mobile system

  International Publications 
 
• "FastTrack: Foreground App-Aware I/O Management for Improving User Experience of Android Smartphones" 
Sangwook Shane Hahn, Sungjin Lee, Inhyuk Yee, Donguk Ryu and Jihong Kim 
USENIX Annual Technical Conference (ATC'18), Boston, USA, July 11-13, 2018 
(Acceptance Rate: 20.1%, 76/378)
• "PCStream: Automatic Stream Allocation Using Program Contexts"  
Taejin Kim, Sangwook Shane Hahn, Sungjin Lee, Jooyoung Hwang, Jongyoul Lee and Jihong Kim 
USENIX Workshop on Hot Topics in Storage and File Systems (HotStorage'18), Boston, USA, July 9-10, 2018 
(Acceptance Rate: 36%, 22/60)
• "SyncGC: A Synchronized Garbage Collection Technique for Reducing Tail Latency in Cassandra" 
Seungwook Han, Sungjin Lee, Sangwook Shane Hahn and Jihong Kim 
Asia-Pacific Workshop on Systems (APSys'18), Jeju Island, South Korea, August 27-28, 2018
• "Improving File System Performance of Mobile Storage Systems Using a Decoupled Defragmenter" 
Sangwook Shane Hahn, Sungjin Lee, Cheng Ji, Li-Pin Chang, Inhyuk Yee, Liang Shi, Chun Jason Xue and Jihong Kim 
USENIX Annual Technical Conference (ATC'17), Santa Clara, USA, July 12-14, 2017 
(Acceptance Rate: 21.2%, 60/283)
• "Improving User Experience of Android Smartphones Using Foreground App-Aware I/O Management" 
Sangwook Shane Hahn, Sungjin Lee, Inhyuk Yee and Jihong Kim 
Asia-Pacific Workshop on Systems (APSys'17), Mumbai, India, September 2-3, 2017
• "Dynamic Erase Voltage and Time Scaling for Extending Lifetime of NAND Flash-Based SSDs" 
Jaeyong Jeong, Youngsun Song, Sangwook Shane Hahn, Sungjin Lee, and Jihong Kim 
IEEE Transactions on Computers, Vol. 66, 2017
• "To Collect or Not to Collect: Just-in-Time Garbage Collection for High-Performance SSDs with Long Lifetimes" 
Sangwook Shane Hahn, Sungjin Lee, and Jihong Kim 
Design Automation Conference (DAC'15), San Francisco, USA, June 7-11, 2015 
(Acceptance Rate: 20.5%, 162/789)
• "Lifetime Improvement of NAND Flash-based Storage Systems Using Dynamic Program and Erase Scaling" 
Jaeyong Jeong, Sangwook Shane Hahn, Sungjin Lee, and Jihong Kim 
USENIX Conference on File and Storage Technologies (FAST '14), Santa Clara, USA, February 17-20, 2014 
(Acceptance Rate: 18%, 24/133)
• "Improving NAND Endurance by Dynamic Program and Erase Scaling" 
Jaeyong Jeong, Sangwook Shane Hahn, Sungjin Lee, and Jihong Kim 
USENIX Workshop on Hot Topics in Storage and File Systems (HotStorage'13), San Jose, USA, June 27-28, 2013 
(Acceptance Rate: 22.8%, 16/70)
• "SOS : Software-based Out-of-Order Scheduling for High-Performance NAND Flash-Based SSDs" 
Sangwook Shane Hahn, Sungjin Lee, and Jihong Kim 
IEEE 29th Symposium on Mass Storage Systems and Technologies (MSST'13), Long Beach, USA, May 6-10, 2013 
(Acceptance Rate: 27.5%, 30/109)

  Domestic Publications  
• "PMPro: A Fully-Integrated Storage I/O Profiler for Next-Generation Non-Volatile Memory-Based Storage" 
Sangwook Shane Hahn and Jihong Kim 
Korea Software Congress (KSC'17), Busan, Republic of Korea, December 20-22, 2017
• "qtar: Design and Implementation of the Optimized tar Command with FTL-level Remapping Technique" 
Jeongseok Ryoo, Sangwook Shane Hahn and Jihong Kim 
Korea Computer Congress (KCC'17), Jeju, Republic of Korea, June 26-30, 2017
• "AIOPro : A Fully-Integrated Storage I/O Profiler for Android Smartphones" 
Sangwook Shane Hahn, Inhyuk Yee, Donguk Ryu and Jihong Kim 
Journal of KIISE (JOK'17), Vol. 44, no. 3, pp. 232-238, 2017
• "Garbage Collection Synchronization Technique for Improving Tail Latency of Cloud Databases" 
Seungwook Han, Sangwook Shane Hahn and Jihong Kim 
Journal of KIISE(JOK'17), Vol. 44, no. 8, pp. 767-773, 2017
• "qtar: Design and Implementation of the Optimized tar Command with FTL-level Remapping Technique" 
Jeongseok Ryoo, Sangwook Shane Hahn and Jihong Kim 
Journal of KIISE (JOK), Accepted for Publish
• "AIOPro : A Fully-Integrated Storage I/O Profiler for Android Smartphones" 
(Best Paper Award) Sangwook Shane Hahn, Inhyuk Yee, Donguk Ryu and Jihong Kim 
Korea Computer Congress (KCC'16), Jeju, Republic of Korea, June 26-30, 2016

• Research for SSD Endurance Improvement with Data Compression (R&DB, Dec 2013 ~ Nov 2015)
• Host-Level FTL Implementation using Enterprise SSD (R&DB, Oct 2014 ~ Sep 2015)
• Research for I/O Stack Performance Improvement for UFS Storage (R&DB, Jul 2015 ~ Aug 2016)
• Research for Cross-Layer Optimization for NAND Flash-Based Storage System (R&DB, Jul 2016 ~ Present)
• Research for an Integrated Optimization Solution for next-generation NAND-based Storage Devices (Ministry of Science, ICT and Future Planning, Dec 2013 ~ Nov, 2016)
• Study on Storage Systems for Exa-scale High-Performance Computing Systems (Korea Research Foundation, Oct 2015 ~ Present)

• International Patent, United States, DATA STORAGE DEVICE FOR COMPRESSING INPUT DATA, 2018.  
• International Patent, China, DATA STORAGE DEVICE FOR COMPRESSING INPUT DATA, 2017.  
• Domestic Patent, Republic of Korea, GARBAGE COLLECTION METHOD FOR FLASH MEMORY, 2017.
• Domestic Patent, Republic of Korea, DATA STORAGE DEVICE FOR COMPRESSING INPUT DATA, 2016.