KorDef-LLM is a 12B-parameter language model fine-tuned from google/gemma-3-12b-it on a domain-specific instruction corpus drawn from publicly available, unclassified Korean defense administrative-rule (행정규칙) and educational PDFs.

This model accompanies the manuscript "An Open Pipeline for Domain-Adaptive Instruction Tuning of Korean Defense Large Language Models" (submitted to PeerJ Computer Science). It is released for research and educational use only, with the limitations and out-of-scope uses described below.

Released Artifacts

Component	Location
Model weights (this page)	HuggingFace `graphuser/kordef-12b`
Instruction corpus + evaluation set	Zenodo `10.5281/zenodo.20083055`
Inference and evaluation code	GitHub `gshwan22/KorDef-LLM`

Model Description

Base model: google/gemma-3-12b-it (Gemma-3, 12B parameters, instruction-tuned)
Fine-tuning: Supervised instruction tuning (full SFT, FSDP distributed; not LoRA)
Domain: Korean defense administrative rules, doctrine documents, and educational materials (all publicly available, unclassified)
Training corpus: Combined prompt-generated and document-grounded instruction–response pairs; the prompt-generated subset (235,367 pairs) is publicly released via Zenodo
Training steps: 7,875

Intended Use

KorDef-LLM is intended for:

Research on Korean professional-domain language modeling and domain adaptation
Educational reference-style question answering over Korean defense administrative-rule documents
Comparison studies and reproducibility evaluations in Korean NLP
A base model for further research-oriented fine-tuning in related Korean professional domains

The model is NOT intended for:

Autonomous decision-making in military operations, procurement, maintenance, targeting, or any safety-critical procedure
Generation of classified, sensitive, or operationally restricted content
Deployment in real-world high-stakes settings without institutional review, retrieval grounding, and human expert oversight
Any use that violates applicable laws, regulations, or the Gemma Terms of Use

Evaluation Summary

KorDef-LLM was evaluated on two complementary benchmarks; full details are reported in the accompanying paper.

KMMLU (general Korean reasoning, 5-shot)

Model	KMMLU (%)
A.X-4.0-Light	55.7
KorDef-LLM (ours)	48.0
Gemma-3-12B (base)	46.0
Qwen-2.5-7B-Instruct	45.8
EXAONE-3.5-7.8B-Instruct	45.3
Llama-3.1-8B-Instruct	41.6

KorDef-LLM ranks second among six compared models on KMMLU, exceeding the base model and three additional open Korean/multilingual baselines, indicating that domain-adaptive instruction tuning preserves general Korean reasoning ability.

Source-Grounded Evaluation (N=323, public defense PDFs)

Paired comparison against the base Gemma-3-12B under identical context, prompt, and decoding conditions:

Metric	Gemma-3-12B	KorDef-LLM	Δ	p (Wilcoxon)
Token-F1	0.398	0.428	+0.030	< 1e-7
ROUGE-L	0.380	0.402	+0.022	< 1e-3
Character 3-gram Jaccard	0.258	0.281	+0.023	< 1e-4
Evidence-token recall	0.534	0.549	+0.015	0.108 (n.s.)
Mean answer tokens	45.2	41.2	−4.0	< 1e-11

Statistically significant improvements over the base model in three content-overlap metrics, with no significant change in evidence recall or refusal rate.

In a cross-model comparison against five baselines (Gemma-3-12B, EXAONE-3.5-7.8B, Qwen-2.5-7B, Llama-3.1-8B, A.X-4.0-Light) on the same evaluation set, KorDef-LLM achieves the highest mean evidence-token recall, the metric most directly tied to source faithfulness in source-grounded QA. The train/eval overlap audit confirms zero exact question, zero exact answer, and zero near-question (Jaccard ≥ 0.80) overlap between the training corpus and the evaluation set.

Known Limitations

Effect sizes are modest. The improvements over the base model on a source-grounded evaluation are statistically significant but small in absolute magnitude (~3 percentage points on Token-F1). The model is not a substitute for retrieval-augmented generation or human expert review.
Evidence recall and refusal rate are not significantly improved. While source-grounded inference shows favorable trends on these source-faithfulness metrics, none reach statistical significance against the base model. Source faithfulness in the deployed system should be enforced via retrieval grounding and explicit citation requirements.
The training corpus is partially released. Only the prompt-generated subset of the training corpus is publicly available via Zenodo. The full released corpus, source manifest, segments, and evaluation set are available; the model weights are released here.
No human expert evaluation. Evaluation was conducted using automatic metrics. Future deployments in any operational or educational context should be validated by qualified Korean defense doctrine experts.
Defense-domain language specificity. The model is tuned for Korean defense administrative-rule and educational text style. It may produce overly formal or excessively verbose responses outside this domain.
Hallucination risk. Like all large language models, KorDef-LLM may generate plausible-sounding but factually incorrect content, especially when asked about topics not covered by its training corpus or when source context is incomplete.

Safety Considerations

Dual-use awareness: Defense-domain language modeling carries inherent dual-use considerations. The released model and corpus contain only publicly available administrative-rule and educational content, not operational, tactical, or classified information.
Recommended deployment pattern: For any real-world use, we recommend retrieval-augmented generation with explicit source citation, deployment within controlled (e.g., air-gapped) infrastructure, and human expert review of outputs in any consequential workflow.
Memorization and data extraction: The model has been trained on Korean defense administrative-rule text. While the training data is unclassified, users should still exercise caution regarding prompts that attempt to extract training data verbatim.
Prompt injection: As with all instruction-tuned LLMs, the model may be vulnerable to prompt-injection attacks in deployed agentic settings. Defensive measures (input sanitization, instruction layering, output filtering) are recommended.

How to Use

python

from transformers import AutoModelForCausalLM, AutoTokenizer

model_name = "graphuser/kordef-12b"
tokenizer = AutoTokenizer.from_pretrained(model_name)
model = AutoModelForCausalLM.from_pretrained(
    model_name,
    torch_dtype="bfloat16",
    device_map={"": 0},  # single GPU; avoids CPU offload
)

# Source-grounded prompting (recommended pattern)
prompt = """다음 [출처]를 참고하여 [질문]에 정확히 답변하시오.

[출처]
(여기에 관련 행정규칙 또는 문서 발췌 삽입)

[질문]
(여기에 질문 작성)

[답변]"""

inputs = tokenizer(prompt, return_tensors="pt").to(model.device)
outputs = model.generate(
    **inputs,
    max_new_tokens=192,
    do_sample=False,
    repetition_penalty=1.05,
)
print(tokenizer.decode(outputs[0][inputs.input_ids.shape[1]:], skip_special_tokens=True))

Citation

If you use this model, please cite the paper and the dataset:

bibtex

@article{gwak2026kordef,
  title   = {An Open Pipeline for Domain-Adaptive Instruction Tuning of Korean Defense Large Language Models},
  author  = {Gwak, Sang-Hwan and Choi, Ji-Young and Jeong, Chang-Hoo and Lee, Gunwoo and Kim, Ina and Lee, Kyung-Ha},
  journal = {PeerJ Computer Science (submitted)},
  year    = {2026}
}

@dataset{kordef_corpus_2026,
  title     = {KorDef-LLM: Korean Defense Domain Instruction Corpus and Source-Grounded Evaluation Set},
  author    = {Gwak, Sang-Hwan and others},
  year      = {2026},
  publisher = {Zenodo},
  doi       = {10.5281/zenodo.20083055}
}

License

Model weights: Gemma Terms of Use (the model is fine-tuned from google/gemma-3-12b-it). Users must comply with the Gemma Terms.
Released corpus (Zenodo): CC-BY-4.0
Code (GitHub): MIT

Acknowledgments

This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT and DAPA) (No. RS-2024-00452972).

Contact

For questions about this model or the accompanying paper, please contact the corresponding author at kyongha@kisti.re.kr or open an issue on the GitHub repository.