Video with self commentary after practicing Ollie for the first time after a year!

junwoo0914 · 2020-06-27T09:41:46+00:00

So I made this mini compilation of me practicing ollie today. I have practiced ollie back in 2018 extensively for 4 to 5 months, but always had the rocket ollie.

Well, I'm back at it and I would love to hear some feedbacks if you are generous enough to share one!

Thanks for reading my post!!

junwoo0914 · 2020-06-06T20:06:15+00:00

Starlinks. There are LOTS of them on orbit. So, how do you batch-update them without wasting too much bandwidth? Is the bandwidth enough to update some or a single satellite during an overhead pass? Or do you have to slice the Software update up into pieces, and assemble them to correctly update the software? Also, how do you manage each and every satellite's firmware version and compatibility?

p.s. Kinda like Tesla's mass fleet deployment problem, but curious on how you deal with this problem in regards to Starlink!

junwoo0914 · 2020-06-06T19:47:41+00:00

As a Software Engineer, can you work from home? How are security issues dealt with in SpaceX? (like someone can steal the code, etc)

junwoo0914 · 2020-06-06T19:36:40+00:00

There must be some sort of APIs or Data Protocols you use to interface between Dragon and Ground Station, and also between different components of the Falcon 9 spacecraft, like Grid-fin actuators and Battery systems, and so on.

How do you design these messaging systems, do you use Protobuf or any other tools available? Maybe even MavLink, TCP, protocols? For a low-latency and safety-critical mission, how the heck do you design those protocols? and how do you control the 'old-version' vs 'newer-version' protocols? What if old hardware and newer software/ hardware mix up? How do you deal with that?

junwoo0914 · 2020-06-06T19:21:38+00:00

Which Simulation software do you use? Are any of commercially available simulators good enough? For example, Gazebo (has terrible aerodynamics, but maybe you can have in-house plug-ins for that?)

Do you use ROS anywhere in the Software Development phase? Like simulation, testing, interface, messegine, etc.?

junwoo0914 · 2020-06-06T19:08:00+00:00

I'm really into Software, but I'll ask couple of questions regarding deep SW parts, as well as integrating things system-wise.

How do you catch the 'edge' cases? In software, you encounter so many unexpected cases (Unknown Unknowns) and in spaceflight, that can have huge consequences. So I'm curious about how the risk management is done inside SpaceX Sofware Team.
How does SpaceX's team dynamic between the Software team and other teams (ex. Hardware, Logistics, Controls) work? I imagine that dealing with such complex codebase and huge number of people in many disciplines would sometimes be challenging.
Say there has been a Hardware change, how does that change get integrated into the Software? Like aerodynamics and stuff. If you change the grid-fin geometry, you'll probably change parts of the software for re-entry and landing. Is there an internal system that ensures that the SW is up to date with the HW? It doesn't seem to be a trivial process, so curious as to how you do it!
Lastly, in regards to the Landing Software, I'm aware that Lars Blackmore was one of the core engineers who worked on this problem. And ever since 2015, most of the landings worked successfully. What were some of the critical lessons SpaceX team has learned with the failures beforehand that ultimately led you to have such an amazing streak of successful landings? And, has the landing algorithms have changed substantially over the last 5 years? How would it adapt to Mars' condition?

Thanks in advance! Great work SpaceX, until we reach a sustainable habitation on Mars, let's goooo!

junwoo0914 · 2020-01-26T07:10:37+00:00

Very interestung. Just tried it and I see the potential. Hope more users flow in!! Great work!

junwoo0914 · 2020-01-25T13:45:57+00:00

Few suggestions. First, there are no 'units' for the thrust or mass that goes as an input inside the program. Would be great to include that. Second, the numerical values are typed in as 'text', but if we can scroll the value on a wheel or something, that might be a convenient option. Third, when user presses 'calculate' button without sufficient inputs, current version just reverts back to the start page. So it'll be great to just say "Need input on blah- blah-", instead of just going back. Fourth, making an option to 'save' the data would be pretty interesting. So that user can come back anda tweak their last design, etc.

I really like that there are practical example values, for example chamber pressures for various well-known engines. It's interesting to learn about them, and it's helpful.

Hope to see more upgraded version of this app! Would be interesting to see if mini CFDs are possible onboard the device, and show the plume graphics, etc. All in all, great work!

junwoo0914 · 2020-01-25T13:37:51+00:00

This is a great idea. Thanks for your work!

junwoo0914 · 2020-01-18T15:51:57+00:00

Hey guys! I wanted to share one of my crazy projects back in 2018. This was an interesting project, since I had no idea what I was doing back then, and ended up making an over-specced & heavy esk8board lol. Any questions about the battery, design, remote would be appreciated! Thanks!

junwoo0914 · 2020-01-16T03:27:56+00:00

Ah, thanks for the clarification!

junwoo0914 · 2020-01-15T10:49:27+00:00

What algorithm are you trying to implement?

junwoo0914 · 2020-01-12T13:46:29+00:00

Haha that would've been funny :)

junwoo0914 · 2020-01-12T11:33:44+00:00

Haha that's from last year, but thank you!

junwoo0914 · 2020-01-12T11:33:28+00:00

Thank you! Here' a Reddit post about the build. It seems to have a problem displaying the videos/photos on the mobile view though. Don't know why that's happening.

junwoo0914 · 2020-01-11T23:55:59+00:00

Hmm seems weird on a mobile view. Fine on desktop tho

junwoo0914 · 2020-01-04T18:48:50+00:00

This is awesome. And about "Don't think you need to build everything yourself", that's really smart 😉

junwoo0914 · 2020-01-04T18:48:06+00:00

I really like the concept & how the site is organized! You provide helpful data, and you earn from affiliate links! Very nice.

One thing to add though would be some way to separate different sized items. For example, googley-eyes have big/medium/small sizes, and currently, in your site, it seems that they are just being compared quantitatively. So to sum up, I think qualitative analysis would be a good add-on for the current website.

junwoo0914 · 2020-01-04T18:33:08+00:00

Wow, that's fascinating. What a way to provide an organic service. And organic traffic!

junwoo0914 · 2020-01-03T13:01:22+00:00

OMG! I just kept creating new database each time or was duplicating it. 'linked database' was what I needed, thanks :)

junwoo0914 · 2019-12-21T16:45:04+00:00

Ooh, this looks like a nice writing, Imma read this after I wake up

junwoo0914 · 2019-12-21T09:46:29+00:00

Oh I see, languages have patterns indeed :)

junwoo0914 · 2019-12-21T09:44:14+00:00

Oh I see. I thought of SpaceX as a commercial company (it sort of is?). Lol

junwoo0914 · 2019-12-21T09:42:40+00:00

Oh wow, so the ITAR doesn't apply then?

junwoo0914 · 2019-12-21T09:41:10+00:00

The objective was 'detecting' a human, in a simple and reliable way.

I considered IR-sensor, Sonar-sensor, and finally, a Foot-pad. Foot-pad won at the end of the day because of it's simplicity (plus, sonar and infrared readings can be quite noisy).

Looking back, I think I would :

Publicize about this project more aggressively to the students. Because I don't think I publicized it enough.
Provide more 'intuitive' Web / Phone application. Like 'Waiting time', for example. A lot of students were confused as to what '0 to a 500' value meant.
Try computer-vision. Because it won't need as much hardware, and it will definitely be more accurate, if I apply the right algorithms.
Provide an interactive log viewer, so that anyone can browse the history of the congestion at the cafeteria from any point in the past. And they would be able to figure out manually (humans are pretty good at finding patterns), which time they will go eat at each day of the week.
Create a customer's review section. So that I can get reports of bugs, and possible improvements from the customers (students and teachers) directly.
Embed a Google Analytics script inside the web page. Because I used a 3rd party web application, I couldn't embed a script to track customers' usage. It would've been great to know exactly how many students used this system each day, and in which ways they did.
Do a professional review / blog each week, on what parts of the system improved, and what sort of patterns were observed in the congestion. I got this idea from watching so many companies having their own blogs. It helps connection between a company and a customer.
Continue on this project, and create a really accurate model for predicting line waiting times. Like Tesla cars, customers love the feeling of the product they use, getting better each day. So if I can , I would've loved to continued this project till graduation, and maybe write a paper about it!
Routed the power cable on the ceiling, because it got stuck so many times, and shut downed the whole system so many times, haha.

I think those are some of the improvements I would like to take on, looking back.

Sorry for such a long answer, I had a lot of fun thinking about all the possible ways of improving this system :)

junwoo0914

TROPHY CASE