This interview was prepared to congratulate Ha-rim Ji (Class 17, Department of Mechanical Engineering) and Do-Hyun Lee (Class 18, Department of Mechanical Engineering) for winning the 2021 College of Engineering Textbook Rewriting Competition and hear about the award and the engineering college curriculum.






 

Q. First of all, please introduce yourself.

Ha-rim Ji: This is Ha-rim Ji from the class 2017 of the Department of Mechanical Engineering. I am interested in developing virtual reality hardware.

 

Do-Hyun Lee: This is Do-Hyun Lee from the class 2018 of Mechanical Engineering. I recently went to the military and am waiting for my return to school.



 

Q. What motivated you to participate in the competition?

Ha-rim Ji: When I was taking fluid mechanics in my sophomore year, I found errors in a textbook called Fluid Mechanics (author F. M. White) and organized the errors before going back to school. Then I found out that there was a competition and decided to participate.

 

Do-hyun Lee: Actually, I wasn't very interested in contests or competitions in my first and second years. However, during this vacation, I got into the habit of frequently visiting the homepages of the College of Engineering or Department of Mechanical Engineering, so I found out that there was a textbook rewriting contest. At the same time, I remembered an error in the textbook I saw in a lecture three years ago, so I decided to participate.



 

Q. In which subject did the recipient found an error and felt that it needed improvement? And please briefly introduce what you suggested.

Ha-rim Ji: In fluid mechanics, we found an error in the application of the conservation of momentum and angular momentum of Reynolds transport theorem in a non-inertial coordinate system.

 

In the textbook, I mentioned the error that occurred during the differentiation process while deriving the velocity vector and acceleration vector in the non-inertial coordinate system. I also pointed out that the differentiation of vectors is not very intuitive when it becomes indistinguishable between vectors and 3x1 matrices. So, to distinguish between vectors and matrices, a new concept called basis vector envelope of the coordinate system was introduced, and a new vector notation was proposed to make convenient use of this concept. After that, based this notation, the content of deriving the Reynolds transport theorem in the non-inertial coordinate system shown in the textbook is also included.

Do-hyun Lee: Actually, I didn't find a huge error. I am a person who cannot tolerate omissions when studying, but while studying a concept that appears when solving a two-dimensional wave equation called the Bessel equation, I felt that the initial term setting of the differential equation was not smooth. At the time, I even asked the professor a question.

 

In the textbook, I found a solution usinglye of the four initial value candidates, but I tried all four and was able to confirm that there are actually various types of solutions. In fact, this is not an important discovery academically, but I think it is possible for a student to have a deep understanding of the study just by meticulously calculating all the solutions.



 

Q. Did you feel anything through this competition?

Ha-rim Ji: Despite what I know, it was very difficult to think about how to put this content in a textbook. As I pondered how to explain concepts that should be intuitively understood and how to show the induction process, I came to understand a little bit of the feelings of those who wrote textbooks. Still, as I was preparing for the competition, I was able to understand the concepts I came up with more clearly because I was able to rearrange the concepts myself.

 

Do-hyun Lee: In engineering math class at university, I couldn't understand the professor's words no matter how much I thought about it, so I had the experience of solving it by myself. So this contest is a thank-you contest for helping me clear my doubts.



 

Q. From the perspective of an undergraduate student, what is your opinion the current engineering college lectures? Are you satisfied with the current curriculum? If you are not satisfied, what do you think needs to be improved?

Ha-rim Ji: If there is something missing from the current curriculum, I think the lectures dynamics and control are lacking. Robotics/control is a field that comes to mind when you think of mechanical engineering. As the name suggests, dynamics and system control are key elements. However, in the Department of Mechanical Engineering, there arely three lectures related to this field: Dynamics in the second year, modeling and control of mechanical systems in the third year, and Introduction to Robotics. In the case of mechanical system modeling and control, since I cover a lot of content ine semester, I cannot even cover the root locus method, compensator design, Nyquist diagram, etc. Depending the semester, the Introductory Robotics course covers SLAM or other topics instead of Forward Dynamics or Inverse Dynamics, which you must know to control the behavior of robots. Personally, I wish there was a separate lecture this topic.



 

Q. Do you have any lectures that you would recommend to other undergraduate students?

Ha-rim Ji: I recommend Professor Dong-Jun Lee's lecture mechanical system modeling and control. In this lecture, you can effectively convey the overall content of control and get a glimpse of the professor's experiences. Besides, the exam questions are fun and the exam time is really generous, so there is a lot to learn while solving the questions. If you listen hard and worry a lot by yourself, synergy is good.

 

Do-Hyun Lee: Second-year students might want to study the four major mechanics and study in-depth, but I was able to study solid mechanics in depth through the mechanics and design lectures. We recommend mechanics and design that you can familiarize yourself with MATLAB.



 

Q. Lastly, what do you think a good textbook is?

Do-hyun Lee: I think that a good textbook should have a good explanation, even if it is thick because it has a lot of volume. This is because when you read engineering textbooks, you come across a lot of complex formulas.

 

 

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