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"The more challenges I overcome, the more my pride rises."


Juhwan Choi, Ph.D., Team manager of Solver 2 team

Juhwan Choi, Ph.D., is an expert researcher and developer who has been involved in the developed of RecurDyn for 13 years. He finds great enjoyment in and gains great satisfaction from tackling the many challenges that are involved in developing such a complex program.

 
 

Education

- (1998) Obtained a bachelor's degree in Mechanical
   Engineering of Hongik University
- (2000) Obtained a master's degree in Mechanical Engineering
   of Seoul National University
- (2009) Obtained a Ph. D. degree in Mechanical Aerospace
   Engineering of Seoul National University


Major Development Achievements
For RecurDyn

- (2012) Developed General Surface Contact, etc.
- (2011) Developed Non-Linear Material (Hyper-Elastic, Plasticity) and
   RecurDyn/Durability
- (2010) MTT3D Contact and Performance Improvement
- (2009) Developed RecurDyn/EHD
   Upgraded Finite Element and Stress Recovery
- (2008) Contact Elements and Performance Improvement (Developed
   Solid Contact )
- (2007) Developed Solver Re-structuring and Primitive Contact of
   MTT2D/3D
- (2006) Developed the earlier version of UI in ProcessNet
- (2005) Developed the UI of Yamaha Toolkits (Crank, Piston, etc.)
- (2004) Developed the UI of Belt, Gear, and HAT
- (2003) Developed the UI of Belt, Gear, and HAT
- (2002) Developed the UI of Chain and MTT2D
- (2000~2001) Developed the basic module of UI in RecurDyn V4 (Part
   Mode, etc.)

   

What are your feelings about FunctionBay?
FunctionBay is like my home. Sometimes, I feel more comfortable at FunctionBay than my home. Researching and developing something for the company gives me great pleasure. I feel that the bond between myself and the other employees of FunctionBay gives my life meaning, and I get great joy and pride by sharing ideas and opinions with my colleagues. We are developing and growing as people together. I would like to contribute what I can so that everyone in the FunctionBay family can find a little more joy and a little more satisfaction from being here.

Please tell the readers about the areas of RecurDyn that you are responsible for.
I usually develop FEM (the Finite Element Method) related with MFBD (Multi-Flexible Body Dynamics) or algorithms related with contact analysis. There are a lot of challenges in developing these aspects of RecurDyn because dynamic analysis of contacts or finite elements involve strong nonlinearities. But these fields are fun for me and solving the challenges gives me a strong sense of accomplishment.
In addition, I'm also involved in the development of various other aspects of RecurDyn related with MFBD, such as FFlex, RFlex, Contact, MTT2D/3D, EHD, and Durability, as well as managing the Solver 2 team. If I have the opportunity, I want to develop modules to perform thermal analysis or fluid dynamics, which I am very interested in.

What are some of the difficulties that you encounter when developing RecurDyn?
There are lots of challenging problems in the solver itself. But fundamentally, I don't think that these challenges are difficult. Usually, with enough time and energy, we can solve these problems. Solving such challenging problems gives me a great sense of satisfaction. In fact, I imagine that not having challenges to solve would be much more difficult for me. Without challenges, life would have much less meaning.
Nevertheless, if I have to identify the most difficult thing for me, I believe that it is not simply the development of new technology. It is related to our goal of becoming the global leader in CAE. During the development of RecurDyn, blindly making improvements can cause problems for the customers. The most difficult part of my job is finding a balance in the development of new technologies that satisfies the customers.

Please tell us about an experience you had in which you feel you gained some value from the development of RecurDyn.
When I was developing algorithms for general solid contact, I was faced with many details that were difficult to find solutions to. I worked so hard on the solving these that I started having dreams at night about things like vertices, edges, and triangles. These things cycled around in my head like an infinite loop until I finally came up with a solution that worked. If we devote all of our energy and strongly focus on developing a particular thing, and then when that problem is solved, this is when we feel that we've done something very valuable. For me, this gives me a sense of accomplishment.
At any moment, we can be experiencing a difficult problem, and we might want to give up before we have reached a solution. But we have to keep going because we can only overcome the problem if we do. I feel that it is like farming. I imagine that the feeling of accomplishment that we get is like the feeling that a farmer gets after he harvests the crops that he spent so much time and energy raising.
In the beginning of solving a problem, I might not know anything about it. But little by little, I learn and grow, and I solve the problem. And I can also make something valuable to the customers that they can benefit from. These kinds of things give me a lot of enjoyment. This is the driving force that keeps me going during the development of RecurDyn.

What do you believe is difference between RecurDyn and other CAE software?
I believe that RecurDyn is the only product in CAE that completely integrates MBD, FE, controls, and optimization into a single product. Most other CAE software is described as multi-physics, but none of these products integrate these parts as simply, deeply, and definitively as RecurDyn. These strengths that RecurDyn has are one of the reasons for our customers using RecurDyn so much. Maximizing this kind of value to the customers is our responsibility in the development of RecurDyn.

What would you like to achieve in the future development of RecurDyn?
First, my short-term target is to give the customers a sense of trust that if they have MFBD problems to solve, they can solve them with our product. To do this, we need to continue the development of RecurDyn. In general, MFBD software contains many parts, but the two parts that I feel are most fundamental and important are the finite elements and the contact elements. My target is to develop complete, mature, and excellent FE and contact modules. I think that this would contribute greatly to building trust with the customers that RecurDyn can solve their MFBD problems.
After that, I would like to develop RecurDyn into an open-structured CAE software package that contains general purpose modules for solving various problems. If someone has domain knowledge, they can use this environment as the basis for their research and development. My dream is that they will be able to do this easily with this new RecurDyn environment. And I would like to become the first customer of this new, open-structured environment so that I can show people in many fields how they can use this environment for their research and product development.

Papers & Journals

Korean Symposium

- (2010) "A Comparison of 4-Node Shell and ANCF Finite Elements for the Dynamic Simulation of Media
   Transport Systems", 2010 Spring Conference for Dynamics and Control Division
- (2012) "INTRODUCTION TO THE NUMERICAL STUDY OF JOURNAL BEARING USING
   ELASTOHYDRODYNAMICS AND MULTI-FLEXIBLE-BODY DYNAMICS", 2012 Spring Conference for
   Dynamics and Control Division


Overseas Symposium

- (2005) "PLUG-IN TOOLKIT, INTEGRATION PLATFORM, ENGINEERING APPLICATION FRAMEWORK
   CONCEPT IN CAE SOFTWARE", ASME
- (2008) "AN EFFICIENT PENETRATION DEPTH CALCULATION ALGORITHM AND AN ENHANCED
   NUMERICAL CONTACT FORCE MODEL", ACMD
- (2009) "Multi Flexible Body Dynamics using Incremental Finite Element Formulation", MULTIBODY
   DYNAMICS 2009, ECCOMAS Thematic Conference
- (2010) "A Comparison of Co-Rotational and ANCF Thin Plate Finite Elements for the Dynamic Simulation
   of Flexible Media Transport Systems", The 1st Joint International Conference on Multibody System
   Dynamics, May 25-27, 2010, Lappeenranta, Finland.
- (2010) "NUMERICAL MODELING AND ANALYSIS OF JOURNAL BEARING WITH COUPLED
   ELASTOHYDRODYNAMIC LUBRICATION AND FLEXIBLE MULTIBODY DYNAMICS", The 5th Asian
   Conference on Multibody Dynamics 2010, August 23-26, 2010, Kyoto, Japan.
- (2010) "A STUDY ON THE STICK AND SLIP ALGORITHM IN CONTACT PROBLEMS OF MULTIBODY
   SYSTEM DYNAMICS", The 5th Asian Conference on Multibody Dynamics 2010, August 23-26, 2010,
   Kyoto, Japan.
- (2012) "A Robust and Efficient General Purpose Contact Algorithm for Rigid and Flexible Bodies", The
   2nd Joint International Conference on Multibody System Dynamics, May 29 - June 1, Stuttgart,
   Germany.


Overseas Journals

- (2009) "An efficient and robust contact algorithm for a compliant contact force model between bodies of
   complex geometry", Multibody System Dynamics. Volume 23, Issue 1 (2010), Page 99-120
- (2011) "Curve-induced distortion of polynomial space curves, flat-mapped extension modeling, and
   their impact on ANCF thin-plate finite elements.", Multibody System Dynamics. Volume 26, 2011, Page
   191-211.
- (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.
- (2011) "Stick-slip algorithm in a tangential contact force model for multi-body system dynamics.",
   Journal of Mechanical Science and Technology, Volume 25, Issue 7, 2011, Page 1687-1694.
- (2012) "NUMERICAL MODELING OF JOURNAL BEARING CONSIDERING BOTH
   ELASTOHYDRODYNAMIC LUBRICATION AND MULTI-FLEXIBLE-BODY DYNAMICS", International
   Journal of Automotive Technology, Volume 13, No 2, pp. 255-261 (2012).


Master Thesis

- (2000) "Numerical Study on the Wall Shear Stress Distribution in the Abdominal Aortic Bifurcation",
   Seoul National University, Korea

Ph.D. Dissertation

 - (2009) "A Study on the Analysis of Rigid and Flexible Body Dynamics with Contact", Seoul National
   University, Korea
   
   
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