Jooyong Yi

Assistant Professor
School of Electrical and Computer Engineering
Ulsan National Institute of Science and Technology
50 UNIST-gil
Ulsan 44919
Republic of Korea

Location: Building 106, Room 401-6

E-mail: jooyong at


Research Interests

I am most interested in reasoning about computer programs for practical purposes. Among many practical applications of program reasoning, I am currently focusing on program repair whereby correct program behavior is inferred, based on which the buggy program is automatically fixed through program synthesis. Program repair can ultimately free millions of software developers from debugging tasks which often become a bottleneck in software development. Apart from practical importance, building software that can modify or build itself is also intellectually intriguing. How can we achieve this challenging goal? I believe an answer is in effectively combining logic-driven techniques such as program analysis and data-driven techniques such as machine learning. Here is one last comment. These days, more and more software bugs are found by publicly available bug detection tools, and many of these bugs are related to software security. If we cannot fix them fast enough, is it a good news or a bad news?

Below are research areas I have been working on.

I am looking for students with strong interest in program repair, program synthesis, program verification, software testing and debugging. Please send me an email with your CV if you are interested in joining the group.

Publications [DBLP] [Google Scholar]

  • Selected Publications
    • [TOSEM22]
      Verifix: Verified Repair of Programming Assignments
      Umair Z. Ahmed, Zhiyu Fan, Jooyong Yi, Omar I. Al-Bataineh and Abhik Roychoudhury
      ACM Transactions on Software Engineering and Methodology (TOSEM), 2022.
    • [IST22]
      Speeding up constraint-based program repair using a search-based technique (PDF) (Tool)
      Jooyong Yi and Elkhan Ismayilzada
      Information and Software Technology (IST), 2022.
    • [ICSE16]
      Angelix: Scalable Multiline Program Patch Synthesis via Symbolic Analysis (PDF) (Tool)
      Sergey Mechtaev, Jooyong Yi and Abhik Roychoudhury
      ACM/IEEE International Conference on Software Engineering (ICSE), 2016.
    • [ICSE15]
      DirectFix: Looking for Simple Program Repairs (PDF)
      Sergey Mechtaev, Jooyong Yi and Abhik Roychoudhury,
      ACM/IEEE International Conference on Software Engineering (ICSE), 2015.
    • [ESEC/FSE17]
      A Feasibility Study of Using Automated Program Repair for Introductory Programming Assignments (PDF) (Tool)
      Jooyong Yi, Umair Z. Ahmed, Amey Karkare, Shin Hwei Tan and Abhik Roychoudhury
      Joint Meeting of the European Software Engineering Conference and the ACM SIGSOFT Symposium on the Foundations of Software Engineering (ESEC/FSE), 2017.
    • [EMSE18]
      A Correlation Study between Automated Program Repair and Test-Suite Metrics (PDF)
      Jooyong Yi, Shin Hwei Tan, Sergey Mechtaev, Marcel Böhme and Abhik Roychoudhury
      Empirical Software Engineering (EMSE), 23(5):2948-2979, 2018.
    • [TOSEM15]
      Software Change Contracts (PDF)
      Jooyong Yi, Dawei Qi, Shin Hwei Tan and Abhik Roychoudhury
      ACM Transactions on Software Engineering and Methodology (TOSEM), 24(3), 18:1-18:43, 2015.
    • [AOSD13]
      Past expression: encapsulating pre-states at post-conditions by means of AOP (PDF)
      Jooyong Yi, Robby, Xianghua Deng and Abhik Roychoudhury
      International conference on Aspect-oriented software development (AOSD), 2013.
    • [ASE06]
      Bogor/Kiasan : A k-bounded Symbolic Execution for Checking Strong Heap Properties of Open Systems (PDF)
      Xianghua Deng, Jooyong Lee and Robby
      Automated Software Engineering (ASE), 2006.
    • [IST10]
      Filtering false alarms of buffer overflow analysis using SMT solvers (PDF)
      Youil Kim, Jooyong Lee, Hwansoo Han and Kwang-Moo Choe
      Information and Software Technology, 52(2):210-219, February 2010.

Recent Professional Activities

Current Graduate Students

  • Md. Mazba Ur Rahman
  • Satbek Abdyldayev
  • YoungJae Kim
  • Seungheon Han
  • Khamit Askar