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"To help RecurDyn users achieve their goals!"

Joon-Shik Yoon, Ph.D., Team manager of Solver 1 team

Joon-Shik Yoon, Ph.D, is a veteran of FunctionBay. He has been part of both the RecurDyn GUI and solver teams. He says that developing software is like arranging the pieces of a puzzle. He greatly enjoys exploring these problems very much.
Based on the knowledge that he has gained through his long experience developing RecurDyn, Dr. Yoon desires to develop RecurDyn into a product that is capable of combining the various fields of mechanics into a single simulation environment. He hopes that this has great benefit for the RecurDyn users.



- (1995) Graduated from Hansung Science High School
   National University
- (1999) Bachelor's degree in the mechanical engineering, Seoul
   National University
- (2001) Master's degree in Mechanical Engineering, Seoul
   National University
- (2012) Mechanical Engineering, Seoul National

Major Development Achievements
For RecurDyn

- (2011 ~ Now) Developed Solver of RecurDyn V7R5/V8R1
   (Particle Dynamics)
- (2009 ~ 2010) Developed Solver of RecurDyn V7R3/R4
   (Multi-Threaded Sparse Linear Solver)
- (2007 ~ 2008) Developed Solver of RecurDyn V7R1/R2
   (Static Analysis of Rigid/Flexible Body)
- (2004 ~ 2006) Developed Solver of RecurDyn V6
   (FFlex Formulation/Element/Integrator, Sparse Linear Solver)
- (2003) Developed GUI for HMCRTS Real-Time Driving Simulation
- (2002 ~ 2003) Developed GUI of RecurDyn V4/V5


Why did you apply to FunctionBay, Inc.?
I was interested in mathematics, physics, and programming from when I was young. As a result, I majored in mechanical engineering. When I was a student in mechanical engineering at Seoul National University, I took a numerical analysis class that was taught by Prof. Chan Jong Kim.

After taking that class, I realized that I wanted to become a developer of mechanical engineering analysis software. Prof. Kim introduced me to FunctionBay, which has become the place where I have been able to achieve this goal. Now already 10 years have passed since I first joined FunctionBay.

What areas of RecurDyn that you are responsible for?
I am the manager of the Solver 1 team. Solver 1 is responsible for all fundamental equations and structures in RecurDyn. Beyond the fundamental formulations for rigid bodies and constraints, my team is also responsible for the development of issues related to computational performance of RecurDyn, the development of toolkits, and the cooperation between RecurDyn and other software packages.

Furthermore, we are currently also doing research into the sparse linear solver for the purpose of increasing the performance of FFlex, especially with very large numbers of degrees of freedom. Recently, we have been working to expand RecurDyn to incorporate the new field of particle dynamics as well.

What do you think is the position of Multi Body Dynamics in the CAE field?
The field of CAE might be larger than you imagine. Compared to FEM or CFD, MBD is a more specialized field for the examination of the overall behavior of a system.

In the past, people solved the problems in their field using their own specialized techniques. But nowadays, computers have become quite powerful and are able to solve complete systems together. I believe that due to the fundamental nature of MBD, it can be an excellent platform in which to combine all the fields of CAE together.

What do you believe is the strength of RecurDyn compared to other CAE software?
RecurDyn has been used in the specialized field of MBD for many years. Starting from a base in MBD, RecurDyn has expanded to include many specialized toolkits, FE modeling for flexible bodies, controls, as well as interfaces to connect to other software. The developers at FunctionBay have been exposed to many complex problems, and we at FunctionBay have developed an expertise from this experience.

Through this experience, we have developed the ability to communicate with our users and to give them rapid feedback about their issues. As a result, we have optimized the process of solving these kinds of problems. Therefore, our product is well-trusted and it has become something very special.

What do you believe will be the future direction of RecurDyn's development?
I think that the future is an age of fusion. Through the integration of various technologies, I believe that in the near future, CAE software will be much easier to use.

Following this trend, I am currently adding particle dynamics into RecurDyn and I am improving the flexible bodies. So in the future, RecurDyn, which is based on MBD, will be able to solve more complex problems as a result of including particle dynamics and flexible body improvements.

What would you like to achieve in the development of RecurDyn in the future?
Because I have experience developing both the GUI and the solver, I believe I can contribute a lot to the creation of the next generation of RecurDyn. Because of my long experience in this field, I think I know how the data flows in complex problems like the ones that we solve.

I would like to develop the next generation of RecurDyn into a platform that includes various technologies in the coming fusion era. My desire is that this platform is able to help a large number of people achieve their own goals.

Papers & Journals


- (2008) "Static Equilibrium Analysis of Multi Physics system", ACMD2008
- (2009) "Modeling and Validation of Flexible Belt Skew Phenomenon in flat belt driving system",
- (2010) "Static Equilibrium Analysis for Interacting System between MBD and FEA", ACMD2010
- (2011) "Particle Dynamics Integration to Multibody Dynamics Using GPU", ICETI2011
- (2012) "Integrated Simulation of GPU Accelerated Particle Dynamics and Multi Flexible Body
   Dynamics", IMSD2012


 - (2011) "Numerical and experimental analysis for the skew phenomena on the flexible belt and roller
   contact systems", Proceedings of
   the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science

Master Thesis

 - (2001) "Heat Transfer and Pressure Drop Characteristics for Various Tube Geometries in Modular
   Tube Bundle Heat Exchanger", Seoul National University

Ph.D. Dissertation

 - (2012) "Numerical and experimental analysis for the skew phenomena on the flexible belt and roller
   contact systems", Seoul National University

Interview List

Juhwan Choi, Ph.D,
Team manager
(Solver 2)

Graham Sanborn, Ph.D, Principal research engineer (Solver 2)

Jeonghan Lee, Ph.D., Duty general manager (Solution Group)

Sun Kim, Ph.D.,
Team manager
(GUI 1)

Joon-Shik Yoon, Ph.D,
Team manager
(Solver 1)

Han-Sik Ryu, PhD, CTO