AR-CAD

967 Central Avenue
Los Alamos, NM 87544
USA

Day Phone: (505) 310-2069
Evening Phone: as above
Email: askoh@ar-cad.com

To use my expertise in Engineering, Mathematics and Pure Object Oriented Programming to develop simulation software and/or create products or systems for education and industry.

Very good in Engineering Mathematics, Multibody Dynamics, Vibrations, Controls, Numerical Analysis, Pure Object Oriented Programming (Smalltalk), CAD, Solid Modeling, OpenGL, AutoCAD API, COM, Visual Lisp. Good in Finite Element Analysis, Stochastic Processes, Statistics, Systems Engineering. Developing in Photogrammetry and Image Processing.

Birth: 1957
Married: 1989
Children: Sons (93, 01, 07), Daughters (96, 98)

Health: Excellent
Permanent Resident: USA since 1986

English: Excellent Spoken and Written
Malay: Good Spoken and Written

Chinese: Fair Spoken
French: Poor Spoken and Written

1984

1982
1979

PhD in Engineering Mechanics, GPA 4.0/4.0, The University of Texas at Austin
MSE in Civil Engineering, GPA 3.4/4.0, Princeton University
BA Honors in Engineering, First Class, Cambridge University

1999 to present

Co-founder, Software Developer, AR-CAD
Founder, Software Developer, askoh.com
Developing and commercializing
freeCAD, CADSM, Alibre Motion: 3D CAD with Motion Simulation
http://www.askoh.com, http://www.cadsm.com
'freeCAD' and CADSM are basic 3D CADs with advanced Motion Simulation capabilities. Their motion simulation capabilities are comparable to the best and can provide accurate answers to engineers and scientists in diverse fields. Educators, students and new engineers will find it ideal for the teaching and learning of geometry, kinematics, dynamics, vibrations, mechanisms, linkages, cams, machine design and physics. The program runs on Windows, Linux PC, Macintosh PPC and other Unix's. Assembly data are unchanged across platforms. Alibre Motion is a motion simulation addon for Alibre Design.

Software used:
VisualWorks Smalltalk development system, OpenGL 3D graphics, Business Graphics Object Kit (BGOK), Binary Object Streaming Service (BOSS), Advanced Tools Parser Compiler, DLL and C Connect (DLLCC), COM Connect, GF/ST Graphics Framework, Jun for Smalltalk 3D Graphics Library, RSA encryption, Persistence of Vision Raytracer (POV-Ray), AutoCAD, Visual Lisp.

Software components developed:
GUI for 3D CAD with full 3D pan, zoom, tilt and rotate on an assembly of solids in wireframe or rendered graphics. 2D editor for rectangle, circle, ellipse, and polygon. Grapher for multivariant data. Math components for full and sparse matrix algebra, matrix solvers, Newton Raphson root finder, differential equation solver, symbolic manipulator, fast fourier transform. Multibody dynamics components for motion simulation of dynamics and kinematics of machines. Contact and collision detection algorithms. COM server for motion simulation.

Sep 2006: Released Alibre Motion: Motion Simulation for Alibre Design.
July 2004: Released CADSM: 3D CAD with Motion Simulation
Dec 2000: Open Sourced StCAD: 3D CAD Framework in Smalltalk
July 2000: Released freeCAD: 3D CAD with Motion Simulation

1998 to 1999

Technical Specialist, Mechanical Dynamics Inc. (now part of MSC.Software)
DTI merged with Mechanical Dynamics Inc. for $1,500,000
Programmed a redundant constraint removal algorithm in ADAMS C++, the motion simulation solver most widely used in the automotive and aerospace industries. Used MS Visual C++ and CVS in Windows and Unix.

1995 to 1997

Cofounder and Technical Director, Design Technologies International
Developed and commercialized of Dynamic Designer Motion - a kinematic and dynamic simulation package for mechanisms.
Integrated motion solver (Smalltalk) to AutoCAD and AutoDesk Mechanical Desktop (C++).
Added improved solver and curve-curve contact. Supported sales and marketing. Responded to customer requests.
DTI was a Mechanical Application Initiative partner of AutoDesk.
DDM was awarded 1996 Editors Choice by CADENCE magazine.

1991 to 1995

Senior Lecturer, School Mechanical & Production Engineering, Nanyang Technological University
Lectured and tutored undergraduate course: Dynamics of Machines.
Initiated and conducting research projects. Supervised final year projects.
Developed Dynamic Designer Motion, the first general purpose 3D dynamics simulator program for industry in Asia. It is OOP based and has AUTOCAD input and animation output capabilities. Ready for commercialization in 1995.
Published 5 journal papers, 6 conference papers, 1 report.
Offered consultancy and short course on dynamic simulation.

1985 to 1991

Assistant Professor, Department of Mechanical Engineering, Texas Tech University
Lectured undergraduate and graduate courses: Mechanical Systems Lab., Dynamics, Dynamics/Controls of Systems, Advanced Dynamics, Vibrations, Random Vibrations, Numerical Analysis of Engineering Systems.
Initiated and conducted 7 research projects.
Advised and graduated 2 PhD and 7 MS students.
Published 7 journal papers, 8 conference papers, 3 reports.
Performed numerous services for department, college, university, and community.
Reviewed for ASME J. Comp. Control, ASME Energy Tech. Conf. and Expo., ASCE J. Engrg. Mech., ASCE J. Comp. in Civil Engrg., National Science Foundation, J. App. Mech., Earthquake Engrg. & Struc. Dyn.

1984 to 1985

Visiting Lecturer, Department of Mechanical Engineering, Texas Tech University
Lectured undergraduate Dynamics and Vibrations.

1981 to 1984

Research Assistant, Department of. Aerospace Engineering and Engineering Mechanics, University of Texas, Austin
Conducted graduate research for PhD.
Assistant Instructor, Department of. Aerospace Engineering and Engineering Mechanics, University of Texas, Austin
Lectured undergraduate Statics, Dynamics, and Mechanics of Solids.

1979 to 1981

Research Assistant, Department of Civil Engineering, Princeton University
Conducted graduate research for MSE.
Fall 1980 Laboratory Assistant

Funded

2006

"Die design automation.", Xynatech Inc., USA, custom programming provided.

2003

"Isolation of Airborne Optical Bench," HYTEC Inc., USA, consultancy provided.

2002

"Motion Simulation of Helang Topdeck Installation," Nippon Oil Exploration, Malaysia, consultancy provided.

1994

"Dynamic Designer Motion," Design Technologies International Pty. Ltd., Australia, hardware and software received.

1993

"Simulation of AA gun using multibody dynamics software," Allied Ordnance of Singapore, $5000.

1992 to 1995

"Object Oriented Dynamics Simulator," ATS ComputerCentre, Defence Science Org., hardware and software received.

1990 to 1991

Co-PI, "Noncontact Semiconductor Wafer Handling," part of "Productivity of Single Wafer Fabrication Cell," State of Texas, $52,560.

1989

Co-PI, "Vehicle Response to Aerodynamic Loads," Ford Motor Co., $222,308.

1988

Co-PI, "Vehicle Response to Aerodynamic Loads," Ford Motor Co., $155,706.

1987

Co-PI, "Wind Engineering," Ford Motor Company, $133,794.

Not Funded

1990 to 1991

"Object Oriented Dynamics Modeler"

1989 to 1991

"Quantitative Flow Visualization via 3D Particle Tracking (3DPT)"

1986 to 1989

"Numerical Experiments in Random Vibrations".

1985 to 1989

"Base-Isolation Benefits of Rocking and Uplift"

1990 "Noncontact Handling of Semiconductor Wafer," Research Corporation Technologies, Arizona paid $1000 to review it for patent and commercial potentials.

Journal

1996

Koh, A-S. and Wegienka, A. "Dynamic Designer: A Multibody Dynamics Software" Computer & Graphics, 1996, 20(1) 77-78.

1995

Lee, Y.T., and Koh, A-S. "Performing Euler Angle Rotations in CAD Systems" J. CAD, 1995.

1994

Koh, A-S., and Park, J-P. "Object Oriented Dynamics Simulator," Computational Mechanics, Jun 1994, 14(3) 277287.

1994

Koh, A-S., "Why Use Object Oriented Programming in Engineering?" Mechanical Engineer, ASME Singapore Chapter 199394 Yearbook, Singapore, Aug 1994, 5460.

1992

Koh, A-S., and Du, H. "Multibody Dynamics Theory and Applications," J. The Inst. of Engineers, Singapore, 1992, 32(7) 74-79.

1992

Koh, A-S., Ford, R.G., and Seshadri, T. "Wafer Handling with Levitation," J. Electronic Manufacturing, U.K., 1992, 2(3), 101107.

1991

Koh, A-S. and Hsiung, C-M. "Base Isolation Benefits of Rocking and Uplift: Theory," J. Engrg. Mech. Div., ASCE, 117(1), 118.

1991

Koh, A-S. and Hsiung, C-M. "Base Isolation Benefits of Rocking and Uplift: Numerical Example," J. Engrg. Mech. Div., ASCE, 117(1), 1931.

1990

Koh, A-S. and Mustafa, G. "Free Rocking of Cylindrical Structures," J. Engrg. Mech. Div., ASCE, 116(1), 3554.

1986

Koh, A-S. "Rocking of Rigid Blocks on Randomly Shaking Foundations," J. of Nuclear Engrg. and Design, 97(2), 269276.

1986

Koh, A-S., Spanos, P.D. and Roesset, J.M. "Harmonic Rocking of Rigid Blocks on Flexible Foundation," J. Engrg. Mech. Div., ASCE, 112(11), 11651180.

1986

Spanos, P.D. and Koh, A-S. "Analysis of Block Random Rocking," Soil Dyn. and Earthquake Engrg., 5(3), 178183.

1984

Spanos, P.D. and Koh, A-S. "Rocking of Rigid Blocks Due to Harmonic Shaking," J. Engrg. Mech. Div., ASCE, 110(11), 16271642.

1982

Abdel-Ghaffar, A.M. and Koh, A-S. "Three-Dimensional Dynamic Analysis of Nonhomogeneous Earth Dams," Soil Dyn. and Earthquake Engrg., 1(3), 136144.

1981

Abdel-Ghaffar, A.M. and Koh, A-S. "Earthquake Induced Longitudinal Strains and Stresses in Nonhomogeneous Earth Dams," Earthquake Engrg. and Struc. Dyn., 9, 521542.

1981

Abdel-Ghaffar, A.M. and Koh, A-S. "Longitudinal Vibration of Nonhomogeneous Earth Dams," Earthquake Engrg. and Struc. Dyn., 9, 279305.

Proceedings

2004

Koh, A-S., StCAD: 3D CAD Framework in Smalltalk, Proc. Smalltalk Solutions 2004, Seattle, WA.

1993

Koh, A-S., and Lee, Y.T. "Kinematic and Dynamic Simulation of Weapons" Proc. MINDEF/NTU Seminar '93, Singapore, 1993, 119124.

1993

Koh, A-S., "Object Oriented View of Multibody Dynamics" Proc. Asia-Pacific Vibration Conference '93, Japan, 1993, 12431248.

1993

Koh, A-S., "Automated Kinematic and Dynamics Analysis for Product Design", Proc. ManuTech 93, Singapore, Sep. 1993, 101-107.

1992

Koh, A-S., and Du, H. "Multibody Dynamics Theory and Applications," MINDEF/NTU Seminar, Singapore, Nov. 1992, 5765.

1992

Koh, A-S., and Park, J.P. "Combining Multibody Dynamics and Object Oriented Programming," Int. Conf. Comp. Mech. (ICCME92), Singapore, Nov. 1992, 381386.

1992

Koh, A-S., Ford, R.G., and Seshadri, T. "Noncontact Handling of Semiconductor Wafers," Manufacturing International '92 Conf. 51-62, Dallas, TX, U.S.A.

1990

Ford, R.G., and Koh, A-S. "Noncontact Semiconductor Wafer Handling," Soc. of Manufacturing Engrs. 2nd Annual Conf. on Semiconductor Manufacturing, Tempe, AZ.

1989

Koh, A-S. and Lin, D-C. "Large Monte Carlo Simulation of Duffing Equation," 5th Int. Conf. on Structural Safety and Reliability, 11371144, San Francisco, CA.

1989

Koh, A-S. and Hsiung, C-M. "Parametric Study of 3D Rocking and Uplift," Proc. Pan American Congress of App. Mech., 198201, Rio de Janeiro, Brazil.

1988

Koh, A-S. and Hsiung, C-M. "Base Isolation Benefits of Rocking and Uplift: Theory," Proc. ASCE 7th Engrg. Mech. Div. Specialty Conf., 91, Virginia Polytechnic Institute.

1988

Koh, A-S. and Lin, D-C. "The First Passage Problem: Duffing Equation," Proc. ASCE Probabilistic Methods in Civil Engrg. Conf., 480483, Virginia Polytechnic Institute.

1987

Koh, A-S. and Mustafa, G. "3D Rocking and Toppling on Rigid Foundations," Proc. ASCE 6th Engrg. Mech. Div. Specialty Conf., 254, Buffalo, New York.

1986

Spanos, P.D. and Koh, A-S. "Rigid Body Random Rocking Prediction," Proc. 3rd ASCE Engrg. Mech. Div. Specialty Conf. on Dyn. Res. of Struc., 684691, Los Angeles, CA.

1985

Spanos, P.D. and Koh, A-S. "Stochastic Response of Rigid Blocks on Flexible Foundations," Proc. 8th Int. Conf. on Struc. Mech. in Reactor Tech., 327332, Brussels, Belgium.

1984

Spanos, P.D. and Koh, A-S. "Harmonic Rocking Response of Rigid Equipment Models," Proc. Symposium on Earthquake Effects on Plant and Equipment, 157167, India.

1984

Koh, A-S. and Spanos, P.D. "Seismically Induced Rocking of Rigid Structures," Proc. Eighth World Conf. on Earthquake Engrg., Paper No. 63, San Francisco, CA.

1982

Abdel-Ghaffar, A.M. and Koh, A-S. "3D Dynamic Analysis of Nonhomogeneous Earth Dams," Proc. Int. Conf. on Soil Dyn. and Earthquake Engrg., England.

1982

Koh, A-S. "3D Dyn. Anal. of Nonhomo. Earth Dams Using the Rayleigh-Ritz Method," Proc. 13th Southwestern Grad. Res. Conf. in App. Mech., 213219, Norman, OK.

Reports

1993

Koh, A-S., "Analysis of AOS AA Gun Using Multibody Dynamics Software", to Allied Ordnance of Singapore, Singapore.

1989

Koh, A-S., Park, J-P., and Hsiung, C-M. "Simulation Study of Crosswind Sensitivity," TRFMC896 to Ford Motor Co. USA.

1989

Koh, A-S., Park, J-P., and Hsiung, C-M. "Simulation Study of Crosswind Sensitivity: Supplement," TRFMC897 to Ford Motor Co., USA.

1988

Koh, A-S. and Muyshondt, A. "Vehicle Response to Aerodynamic Loads," TRFMC884 to Ford Motor Co., USA.

Dissertation

1984

"Rocking and Toppling of Block-Like Structures on Rigid or Flexible Foundations Subjected to Harmonic or Random Excitations," The University of Texas at Austin.

Thesis

1982

"Three-Dimensional Dynamic Analysis of Nonhomogeneous Earth Dams Using the Rayleigh-Ritz Method," Princeton University.