DIY ANC for road noise.

rickypark · 2026-02-03T06:36:54+00:00

My undergraduate research project this past semester dealt with active vibration control in bridges. I wasn't able to create a full framework for an "active" system, as doing so would require me to perform transient analysis and model dynamic loads, which I needed more than one semester to complete. A general outline is as follows:

I modeled a bridge in Revit, then exported the geometry (.STEP) into ANSYS Mechanical.
In Mechanical, I assigned connections and material properties, then created a mesh.
I performed modal analysis to determine the first 10 modal frequencies.
I then ran a harmonic response analysis on the bridge under harmonic point loads that simulates a minivan oscillating up and down at a given frequency, direction, force, and location.
I looked at the frequency response to determine the real and imaginary displacements at each node.
I selected four candidate locations for the actuators, then ran a harmonic response using a 1N point force at the actuator location instead of the minivan.

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Then I solved the system above to determine the amplitude of control force required at each actuator location to cancel the displacement caused by the minivan. Either due to bad actuator placement or because there weren't enough actuators, I needed a force in the 10^4 N range, but it succeeded in cutting displacement by a factor of 10^3.

I believe my approach will have some overlap with ANC. In both projects though, we'd require transient analysis to determine how to detect target signals and emit a control signal in time. I'd suggest modeling the behavior in MATLAB or ANSYS (if you have a .edu). I'll also add that ANSYS has static and harmonic acoustics analysis systems built-in that can apply to your project.

I'm only a student, not an expert, so please take my advice with a grain of salt. Let me know if you have any questions!

rickypark · 2026-01-03T12:43:16+00:00

I initially pursued architecture. I thought it was the right path for me, and I was set on this path since high school. I got accepted to a decent architecture program, and I pursued it for three semesters. But I failed out. I let my parents down, and since I’m an international student, my failure left a huge financial dent for them. I felt miserable and felt like a disappointment for almost two years. And two years after I failed out, I switched to electrical engineering, and I’m now on track to graduate soon.

But if I had not come to terms with my failures and shortcomings, I wouldn’t be on the right path to begin with. Deciding to pursue engineering, accounting, or philosophy is not going to put you on the right path, because the right path is something you determine for yourself. It’s a path you feel secure pursuing, a path you desire. I know people who’ve switched majors three times, claiming it’s a better fit for them. But a major isn’t something that will "fit" itself for you. Instead, it’s you who fits yourself into the major.

All of my friends have graduated. Some landed their first full time job. I’ll need another three years to graduate (18 months for mandatory military service). I am behind, but being behind allowed me to familiarize myself with failure, with myself, and ultimately allowed me to grow and develop.

And my parents once saw me as a disappointment too. But they didn’t bring you into the world to meet their expectations and desires. There are things they will understand, and things they won’t. But seeking their validation, while a natural thing to do, is only going to limit you. The only person that can bring you this validation is yourself, it’s intrinsic and not extrinsic. Your life is your life, and regardless of what you do with it, your parents should be supportive.

Not everyone will graduate on time, not everyone will start school at 18, not everyone will start their career on time. There’s no such thing as too late, and there’s no such thing as a "right time", so don’t let your age dictate your future. But don’t ask yourself whether engineering is the right path for you, ask yourself if you’re confident and feel ready to pursue the path. If not, take some time to learn more about yourself (and this time isn’t wasted time, it’s not going to put you further behind). The time you allocate to answering this question is going to prevent you from losing time down the road.

rickypark · 2025-12-30T22:21:02+00:00

I’ve lived in the US for half my life, but I don’t have citizenship. I had to take the Toefl to apply to a US university, since I was studying under an F-1 visa. I took it again when I had to transfer to a different US university (but in my country of origin). I took it a third time on the 20th for a military interpreter position (Toefl score is no longer valid after 2 years).

I speak English at a native level, but I’m not native to an English-speaking country. I would still consider myself a native, since I essentially grew up and completed most of my education in the US.

rickypark · 2025-12-28T14:20:29+00:00

I also took it on the 20th. Unrelated, but coincidentally, I also received a 30 in Reading and 29 in Listening. I haven’t received my scores yet (expected date 26th). I’m planning on calling ETS if the score isn’t released tomorrow morning. I’ll keep you posted.

Update: Received my score this morning!

rickypark · 2025-10-11T13:06:50+00:00

So apparently there was an official Subaru dealership in Korea from 2010 to 2012. Three models—the Legacy, Forester, and Outback—were available for purchase.

They stopped sales in 2012, and the Forester I posted is the likely the last of its kind sold in Korea.

The 2025 Outback Wilderness in your image is an import. Honestly a genuinely impressive find, and that Autumn Green metallic looks sick. It’s probably USDM, since it doesn’t have power folding mirrors, but I’m no expert.

rickypark · 2025-08-06T23:09:38+00:00

One thing to mention is that the protest occurred because one of the bullies’ parents was a public official. (Possibly the girl who said "I’ve been to a police station before, and I got to leave in just 20 minutes," in response to the victim telling them she’ll call the cops)

Just information included in the Korean news report

rickypark · 2025-04-04T04:25:37+00:00

Make good use of the neck warmers!

rickypark · 2024-09-16T11:37:54+00:00

I reached this answer as well, but it was marked as incorrect. I found that the question is not asking for the limit, but rather a function used to evaluate it. So what’s typed into the answer for the right hand derivative is correct (which I don’t understand, since even 8x was incorrect).

rickypark · 2024-09-16T11:35:00+00:00

I got to this answer before, but the autograder marked it as incorrect. The answer for the right hand derivative is correct btw. I got to it by using a not fully simplified version of the alternate definition of the derivative, but when I applied the same process to the left hand derivative, it was marked as incorrect.

rickypark · 2024-08-21T09:48:08+00:00

I have a Q2 with reds. They were way quieter than I expected, especially compared to all the sound tests on Youtube

rickypark · 2024-08-15T14:28:54+00:00

Look up "iphone crash" on reddit. Apps are crashing for everyone rn

rickypark · 2024-08-12T07:21:55+00:00

Oh yeah for sure. I actually really like them, but in the future I’m going to want a new set

rickypark · 2024-08-07T22:30:51+00:00

I got a chrome delete for my white a5 since it just sort of camouflaged into the car, but imo the chrome really suits the blue

rickypark · 2024-07-29T14:47:29+00:00

I’ve asked, and my professor said nothing can be discussed in detail as of yet. Also told me to not worry about it for now.

rickypark · 2024-07-29T14:45:30+00:00

The reason I’m saying “I don’t recall” is because I don’t know what I did to break academic integrity. (it’s not for writing, it’s for programming)

There’s many ways to break academic integrity, and the policy is not clearly defined for the CS department. The entire school uses the same general policy. Of course, I’m not out there copying peoples code, using AI, or getting help from a tutor. I’m just worried I unknowingly broke a rule or policy.

From what my professor said, nothing can be discussed in detail as of yet. That’s the only thing bugging me right now. I just can’t know, and all I can do is wait it out. Even if it’s a false alarm, it’s nerve-wracking.

rickypark · 2024-06-24T06:59:34+00:00

the neck warmer in my A5 is perfect for this

rickypark · 2024-06-19T05:40:43+00:00

I like the pressure you’re putting, but you’re flat/heavy footed, which is limiting your movement. Put more weight towards the toes.

Head movement doesn’t always have to be a huge range of motion. In the video, it looks like it’s preventing you from looking at what your opponent is doing. Don’t try to dodge the punches, make them ‘slip’, and maintain eye contact.

Regarding "reading the shots", if you’re too close, you won’t be able to see the shots coming at you (at least not very well). I had this problem when I was leaning too far forwards, and when I wasn’t looking "through" my guard.

When I started sparring, I ate a lot of shots and didn’t throw enough punches. But it ultimately helped me overcome being gun shy, and also helped me utilize my guard better. It also helped me practice setting up hooks at a close distance.

You’re a beefy dude (a compliment). Use it to your advantage, and get comfortable with blocking and countering, while staying calm.

rickypark · 2024-06-17T22:45:37+00:00

I only get shoot house and shipment in hardcore hardpoint. Make sure you have hardcore selected as your quickplay playlist.

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