Jumini-Ko-1.2B

This repository contains a from-scratch Korean decoder-only LLM checkpoint prepared for HW2.

  • Architecture: RoPE, RMSNorm, SwiGLU, GQA
  • Parameters: 1,260,505,088
  • Export format: Transformers-compatible LlamaForCausalLM key layout
  • Stage: anneal
  • Repo target: properly59/Jumini-Ko-1.2B
  • Source checkpoint: step_00006200/model.pt
  • Export dtype: float16

Training Summary

The model code, tokenizer pipeline, data filters, training loop, checkpointing, evaluation scripts, and export scripts were implemented in this project rather than copied from an existing LLM training repository.

The current export candidate is the V3A retention step-6200 checkpoint. A later low-LR response-only SFT pilot improved SFT validation loss but was not promoted because it did not improve generation or mini-MCQ and degraded all source-bucket losses.

Additional post-export probes were also rejected. A V3B TinyStories low-ratio probe improved its own validation split from step 6200 to step 6300, but it did not beat step 6200 on a same-condition source-bucket comparison and generation remained repetitive/malformed. The exported artifact therefore remains the V3A step-6200 base checkpoint.

License and Data Provenance

The released model artifacts are provided under Apache-2.0. The final promoted training sources were selected from datasets with explicit permissive licenses:

Source Role License
lcw99/wikipedia-korean-20240501 Korean wiki pretraining/replay Apache-2.0
eliceai/korean-webtext-edu Korean educational web pretraining/replay MIT
maywell/korean_textbooks textbook/factual synthetic Korean data Apache-2.0
heegyu/open-korean-instructions capped phase-2 instruction/chat anneal MIT
IkJun1/korean-qa-dataset capped phase-2 Korean QA anneal MIT

Benchmark and diagnostic datasets were kept evaluation-only and were not promoted into the final training mixture.

Local Validation

Train-time held-out validation on the V3A retention split improved monotonically through step 6200:

Step loss perplexity
5700 4.3200 75.19
5800 4.3079 74.29
5900 4.3036 73.96
6000 4.2999 73.69
6100 4.2970 73.48
6200 4.2950 73.33

Source-bucket validation at step 6200. Web/wiki rows are from the stage-gate run with steps=50:

Source loss perplexity
eliceai/korean-webtext-edu 6.2910 539.71
lcw99/wikipedia-korean-20240501 4.9192 136.90
maywell/korean_textbooks:claude_evol 2.7999 16.44
maywell/korean_textbooks:helpsteer 2.7718 15.99
maywell/korean_textbooks:ko_wikidata 2.8092 16.60
maywell/korean_textbooks:tiny-textbooks 2.7239 15.24

Diagnostic results:

Task Result
Korean mini-MCQ 10/20
KMMLU-HARD subset 36/160
Ko-WinoGrande subset 104/200
Ko-PIQA subset 95/200
KoBALT subset 20/200
HAE_RAE_BENCH_2.0 subset 14/60
BELEBELE-KOR subset 47/200
GSM8K-Ko subset 0/100
HRM8K subset 1/60

Rejected Follow-Up Probes

Probe Decision
Low-LR response-only SFT to step 6400 Rejected: SFT validation improved, but generation did not improve and all source-bucket losses worsened.
Average of step 6100/6150/6200 Rejected: no mini-MCQ/generation gain and source buckets were slightly worse than step 6200.
Mixed retention/SFT step 6250 Rejected: retention validation improved slightly, but generation stayed repetitive and source buckets were mostly slightly worse.
Low-LR V3A retention extension to step 6300 Rejected: validation worsened versus step 6200.
V3B TinyStories low-ratio step 6300 Rejected: V3B validation improved, but same-condition source-bucket losses were flat/slightly worse and generation did not improve.

Export Checks

  • Native-vs-HF logits equivalence: ok=true, max absolute diff 0.015625, argmax mismatch rate 0.0.
  • Local Transformers smoke: AutoConfig, AutoTokenizer, and AutoModelForCausalLM load without custom code as LlamaForCausalLM.
  • Local parameter count after HF load: 1,260,505,088.
  • Local submission secret scan: passed on text artifacts; no hf_... token pattern or generic long secret assignment was found.

Intended Use

This checkpoint is intended for course evaluation, reproducibility review, and further controlled research on Korean language-model training from scratch. It is not instruction aligned and should not be treated as a production assistant.

Limitations

  • Free-form generation is still weak and often repetitive or malformed.
  • Math, reasoning, and safety behavior are not reliable.
  • The model can produce incorrect, biased, or unsafe text.
  • Evaluation numbers are local diagnostics unless explicitly marked as public benchmark results.
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