Detecting and Guiding LLM-Generated Korean Poetry with Interpretable Form-level Features

Keunhyeung Park, Seunguk Yu, YoungBin Kim


Abstract
LLMs often struggle with modern Korean poetry, producing outputs that resemble “line-broken prose.” We address two coupled tasks: detecting whether a Korean poem is human- or LLM-authored, and guiding LLMs to generate poetry closer in form to human writing. We quantify the human–LLM gap along four form-level linguistic dimensions: output length (Volume), the diversity and connective use of line-final forms (Structure Variation), the irregularity of line lengths (Rhythmic Irregularity), and adherence to standard orthography (Normative Adherence). We operationalize these dimensions as five interpretable features. For detection, a logistic regression classifier over these five features attains an average AUC-ROC of 83.60 in zero-shot out-of-distribution detection across seven unseen LLMs, versus 75.84 for the strongest baseline in our comparison, KatFishNet, an absolute gain of 7.76 AUC points and a 10.23% relative improvement; one generator-specific punctuation pattern outside our taxonomy remains a boundary case. For generation, expert evaluation on GPT-5.2 prefers feature-guided poems over the unconstrained baseline, and analyses across GPT-5.2 and Gemini-3 show that targeted length, rhythm, and ending statistics move toward the human distribution. These results suggest that interpretable, language-specific features can bridge the diagnosis and guidance of LLM-generated poetry.
Anthology ID:
2026.findings-emnlp.337
Volume:
Findings of the Association for Computational Linguistics: EMNLP 2026
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
Findings
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
7090–7109
Language:
URL:
https://aclanthology.org/2026.findings-emnlp.337/
DOI:
Bibkey:
Cite (ACL):
Keunhyeung Park, Seunguk Yu, and YoungBin Kim. 2026. Detecting and Guiding LLM-Generated Korean Poetry with Interpretable Form-level Features. In Findings of the Association for Computational Linguistics: EMNLP 2026, pages 7090–7109, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Detecting and Guiding LLM-Generated Korean Poetry with Interpretable Form-level Features (Park et al., Findings 2026)
Copy Citation:
PDF:
https://aclanthology.org/2026.findings-emnlp.337.pdf