Hang-Hyun Jo
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socph.bsky.social
Hang-Hyun Jo
@socph.bsky.social
Associate Professor at The Catholic University of Korea; statistical physics and complex systems; co-author of "Bursty Human Dynamics" (Springer, 2018); http://h2jo.xyz; he/him
Reposted by Hang-Hyun Jo
Two variants of the friendship paradox: The condition for inequality between them arxiv.org/abs/2511.06176 a small experimental scientific communication project, encouraged by @socph.bsky.social
Two variants of the friendship paradox: The condition for inequality between them
The friendship paradox -- the observation that, on average, one's friends have more friends than oneself -- admits two common formulations depending on whether averaging is performed over edges or ove...
arxiv.org
November 11, 2025 at 3:08 AM
Reposted by Hang-Hyun Jo
중간고사 문제 출제를 계기로 다시 보기 시작했고, 궁금증을 해결했지만 논문거리는 아닌 것 같아서 이 정도로 남김 ... 을 ChatGPT가 이 정도로 확장해 줌 ... 😶
October 30, 2025 at 11:19 PM
Reposted by Hang-Hyun Jo
친구 역설 또는 우정 역설 (friendship paradox) 에 대해 예전부터 갖고 있었던 의문이 있었는데, ChatGPT의 도움으로 해결한 듯 하다.

1. 결과물: drive.google.com/file/d/1GRSu...
2. 배경 설명: drive.google.com/file/d/1Uqu1...

이런 간단한 일을 *빠르기* 처리하기엔 좋은 듯 함.
twoFP_relation.pdf
drive.google.com
October 30, 2025 at 11:13 PM
Accepted for publication in Chaos! @takayukihir.bsky.social
October 28, 2025 at 1:22 PM
Attending the KPS fall meeting in Gwangju, Korea
October 24, 2025 at 7:35 AM
Reposted by Hang-Hyun Jo
Our paper “Regional disparities in the distribution of public and private healthcare facilities in South Korea” has been published in the international journal PLOS ONE 🎉 (lnkd.in/gMPnhkdC)
Special thanks to our undergraduate co-author (3rd year student) for contributing to this meaningful study.
LinkedIn
This link will take you to a page that’s not on LinkedIn
lnkd.in
September 25, 2025 at 4:17 AM
I just learned that Asia-Pacific Summer School and Conference on Networks and Complex Systems will be held next year at NTU, Singapore. Please check out the official website: apcncs2026.github.io
APCNCS 2026 - Asia-Pacific Summer School and Conference on Networks and Complex Systems
Asia-Pacific Summer School and Conference on Networks and Complex Systems - June 2-5, 2026 at Nanyang Technological University, Singapore
apcncs2026.github.io
September 15, 2025 at 4:48 AM
I just copied the poster of the workshop, which looks interesting.
August 30, 2025 at 6:24 AM
Now attending the RHINO 2025 in Pukyong National University in Busan with participants mostly from Korea and Japan.
We're organizing the "APCTP Workshop on the Roles of Heterogeneity in Nonequilibrium (RHINO 2025)"; the workshop will be held from 29 August to 1 September 2025 in Pukyong National University (PKNU), Busan, Korea.

www.apctp.org/theme/d/html...
APCTP
APCTP
www.apctp.org
August 30, 2025 at 12:30 AM
Our new preprint with @takayukihir.bsky.social is out in arXiv: Takayuki Hiraoka‬ and Hang-Hyun Jo, Hierarchical organization of bursty trains in event sequences, arxiv.org/abs/2508.18281
Hierarchical organization of bursty trains in event sequences
Temporal sequences of discrete events that describe natural and social processes are often driven by non-Poisson dynamics. In addition to a heavy-tailed interevent time distribution, which primarily c...
arxiv.org
August 27, 2025 at 1:05 AM
I submitted my manuscript to the arXiv one week ago, which is still "on hold", and didn't get any message from the arXiv since then. Should I wait longer or take any action?
August 21, 2025 at 7:09 AM
Is this the first journal containing the term "social physics"? In any case, I'm excited to see that such journal has been finally started.
🌐 Journal of Social Physics now accepting submissions exploring the sociophysics, econophysics, and overlaps with computational social science. Share your research!
#CallForPapers #SocialPhysics #ComplexSystems
sciltp.com/journals/jsp
August 15, 2025 at 12:33 PM
Reposted by Hang-Hyun Jo
🌐 Journal of Social Physics now accepting submissions exploring the sociophysics, econophysics, and overlaps with computational social science. Share your research!
#CallForPapers #SocialPhysics #ComplexSystems
sciltp.com/journals/jsp
August 11, 2025 at 8:14 AM
Yet another kind of friendship paradox, an imposter paradox?
Other people have better imposter syndrome than me I bet
August 14, 2025 at 12:09 AM
Our new preprint is out in arXiv: Copula-based analytical results of horizontal visibility graphs for correlated time series arxiv.org/abs/2508.08934 This is from the collaboration with my undergraduate student Jeong-Min Lee.
Copula-based analytical results of horizontal visibility graphs for correlated time series
The visibility graph (VG) algorithm and its variants have been extensively studied in the time series analysis as they transform the time series into the network of nodes and links, enabling to charac...
arxiv.org
August 13, 2025 at 1:06 AM
Attending the summer school on nonlinear dynamics and chaos at KIAS
August 12, 2025 at 1:46 AM
I posted a short article to my blog: brunch.co.kr/@socph/21 . The title is "fixed points and fate". To be precise, the fate of x(t) following the differential equation dx/dt=f(x,r) is determined by the parameter r.
고정점과 운명
비선형 동역학과 카오스 강의를 준비하며 | 다음 주에 열리는 복잡계 여름학교에서 스티븐 스트로가츠의 책 <비선형 동역학과 카오스> 3장을 맡아 강의하기로 했다. 3장의 제목은 갈래치기(bifurcation)다. 간단히 말하면 dx/dt = f(x,r) 형태로 주어지는 미분방정식에서 매개변수 r에 따라 x(t)의 운명이 어떻게 달라지는지를 보는 것이다. 내...
brunch.co.kr
August 10, 2025 at 4:17 AM
Wow cool!
July 30, 2025 at 3:11 AM
Our new preprint is out!

Hyun-Woo Lee, Gerardo Iñiguez @iniguezg.bsky.social Hang-Hyun Jo, Hye Jin Park @hyejinpark.bsky.social "Ranking dynamics in movies and music" arxiv.org/abs/2506.21944
Ranking dynamics in movies and music
Ranking systems are widely used to simplify and interpret complex data across diverse domains, from economic indicators and sports scores to online content popularity. While previous studies including...
arxiv.org
June 30, 2025 at 1:40 AM
Reposted by Hang-Hyun Jo
We also showed that the use of toponyms decays as a power law outside the area they represent.

If you are interested in knowing more, read on here:
doi.org/10.1371/jour...
Geospatial analysis of toponyms in geotagged social media posts
Place names, or toponyms, play an integral role in human representation and communication of geographic space. In particular, how people relate each toponym with particular locations in geographic spa...
doi.org
June 29, 2025 at 2:03 PM
Reposted by Hang-Hyun Jo
We found that toponyms show spatial specificity in their occurrence, unlike many common nouns. Interestingly, toponyms and common nouns describing places (e.g., “park”) behave differently from other common nouns (e.g., “music”) and toponyms referring to places outside the observation area.
June 29, 2025 at 2:03 PM
Reposted by Hang-Hyun Jo
However, quantitative studies of toponyms have been scarce.

In our new article in PLOS One, Takashi Kirimura, Naoya Fujiwara and I tried to address this gap by using a dataset of 400 million geotagged Twitter posts to study the association between toponyms and geography.
June 29, 2025 at 2:03 PM
Reposted by Hang-Hyun Jo
Spatial cognition is vital for all animals. Humans, in particular, use cartographic knowledge and language to understand the environment beyond what we directly experience. Place names (toponyms) play a key role in this cognitive process as they reflect how we mentally structure geographical space.
June 29, 2025 at 2:03 PM
Our paper has been finally published in Physica D! See www.sciencedirect.com/science/arti...
June 15, 2025 at 7:29 AM