Who do you turn to when you want the perfect solution? Not an engineer, says Woosoon Yim.
"What engineers do is find the right compromise," says the chair of the mechanical engineering department. "Engineering design is not about deterministic problems -- about finding the one answer under given conditions. A design problem has many variables; it has infinite solutions. Engineering is about optimization, about how to pick the design that maximizes the efficiency, the cost, or whatever."
A 25-year veteran of UNLV, Yim received the 2011 Harry Reid Silver State Research Award. His branch of mechanical engineering focuses on smart materials and the control of dynamic machines. That means things that move in reaction to their environments. That means robots.
As so often is the case in university labs, Yim's current work started with a completely different idea, one little breakthrough leading to another. In his case: "fishbots" led to robotic catheters for medical applications.
Yim focuses on actuation, which is the force needed to generate motion. His early studies involved "smart" materials made of rubber or silicon. Funding from the Army Research Office led to the development of shock-absorbing materials that would soften automatically to absorb impacts. It had obvious applications for war-zone equipment.
Building on this knowledge, he saw potential for using the pliable materials in robotics. He wondered if he could stimulate motion much like muscles do. He envisioned a robotic device that swam like a fish with a fin rather than with the use of a motor-controlled propeller. Yim's idea would eliminate the noise of the motor -- a critical feature that captured the interest of the Navy.
In 2004, he won his first National Science Foundation (NSF) grant for a feasibility study on the design for a segmented fin made of a soft polymer material. He focused on the "actuation" of the fin, or what causes it to operate. First, he used different electrical voltages to actuate each segment of the fin independently. That led to a second NSF grant to use microwave technology to actuate the segments. His research team did find a novel way to induce movements, but also revealed limits of the proposed technology.
"Frankly speaking, the research hasn't always gone well. But each step, we learn," he says in his quiet and careful voice.
In 2010, he built upon those previous studies and redirected his work for medical applications. He won a third NSF grant and now is mathematically modeling how the tip of a catheter can be robotically controlled.
"Doctors control the tips of catheters remotely, by moving handles manually," Yim says. "What we propose is an active device that can achieve more delicate motion in the human body compared with current passive ones. I named it a robotic catheter. Robotic means it can accommodate a certain type of needed intelligence -- that the computer would make decisions on its own, rather than depending on a human remotely controlling it."
NSF grants have helped Yim expand the base of knowledge in his sliver of the research world. But, he points out, they are also a key to advancing the university, and, by extension, the state.
"My work is far away from the stage of making money at this time," he says. "However, NSF-sponsored research is very important for economic development. Technology companies look to universities when they want to see the future; they look to see who received NSF grants in the past in particular areas to see what's coming in the future."
As department chair, Yim is proud of how UNLV's engineering programs have grown in stature. When he joined the faculty in 1987, no faculty member was a fellow of the American Society of Mechanical Engineers (ASME). Fewer than 3 percent of ASME's worldwide members have achieved that distinction. Now the department has five members, including Yim, who was elected in 2009. He has also served as an organizing chair of several international conferences by ASME and IEEE.
"I used to go to the technical conferences and nobody knew that there was an engineering program in Las Vegas. It was awkward," he says. "Nowadays, they know UNLV's engineering programs. They know how good our programs are here."
