KBS: A Korean Benchmark Suite for Foundation Model Evaluation
Authors: Yeonkyoung So, Jongmin Kim, Sungmok Jung, Gyuseong Lee, Sangho Kim, Jongyeon Park, Joonhak Lee, Seho Pyo, Gyeongje Cho, Seorin Kim, Jisoo Kim, Suyoung Park, Hyunji M. Park, Yelim Ahn, Yeongho Seo, Jaejin Lee
Organizations: Graduate School of Data Science, Seoul National University · Dept. of Computer Science and Engineering, Seoul National University
We present a Korean Benchmark Suite (KBS) comprising Ko-ARC, Ko-GSM8K, Ko-EQ-Bench, Ko-WinoGrande, Ko-LAMBADA, and Ko-IFEval, covering six capabilities across 9,396 items. The suite combines review, localization, direct Korean construction, and redesign for Korean, avoiding a translation-only approach to benchmark adaptation. We evaluate Korean-developed models, multilingual open models, and closed API models under protocols that account for model access, prompt format, and scoring differences. Results show that Korean benchmark scores depend on task construction, scoring rules, prompting, and model post-training. These findings suggest that Korean evaluation should report both final scores and the settings used to obtain them.
Figures & tables
Figure 1: Construction routes of the Korean Benchmark Suite. Translation-based tasks are adapted from English benchmarks through machine translation, correction, localization, and cross-review. Directly constructed tasks are built from Korean sources, while hybrid tasks combine translated items with Korean-specific prompts and automatic checkers.
Figure 2: Examples illustrating why task redesign is needed when adapting English benchmarks to Korean. Each panel contrasts direct transfer with the corresponding redesigned Korean task formulation.
Benchmark
Capability
Items
Construction
English Source
Ko-ARC (easy)
Science QA
2,376
Translated + Refined
ARC-Easy
Ko-ARC (challenge)
Science QA
1,167
Translated + Refined
ARC-Challenge
Ko-GSM8K
Mathematical reasoning
1,319
Translated + Refined
GSM8K
Ko-EQ-Bench
Dialogue-based emotional inference
171
Translated + Refined
EQ-Bench
Ko-WinoGrande
Commonsense/contextual reasoning
1,267
Translated + Refined
WinoGrande
Ko-LAMBADA
Long-context literary understanding
2,255
Newly Constructed
LAMBADA
Table 1: Composition of the Korean Benchmark Suite. Construction type indicates whether the benchmark is translated and refined from an English source, newly constructed from Korean sources, or combines translated items with newly constructed items for Korean-specific constraints. Ko-IFEval consists of 541 translated items and 300 newly constructed items.
Category
Tasks
Models
Main Metrics
Multiple-choice
Ko-ARC, Ko-WinoGrande, Ko-LAMBADA
Open only
acc / acc_norm / acc_npsq
Generation
Ko-GSM8K, Ko-IFEval, Ko-EQ-Bench
Open + closed
exact match / task-specific scores
Generative MCQA
Ko-ARC-gen, Ko-WinoGrande-gen, Ko-LAMBADA-gen
Open + closed
exact match
Table 2: Summary of evaluation formats. Original multiple-choice evaluation is used for open-weight models with log-likelihood access, while closed API models are evaluated using generation-based variants.
Model group
English
DeepL
KBS
Korean-developed
67.29
54.00
59.49
Qwen3.5
51.22
44.14
46.49
Gemma 4
72.56
60.14
67.05
Table 3: ARC accuracy (%) using NPSQ under chat prompting. All versions are restricted to the same 2,376 Easy and 1,167 Challenge items. Scores are averaged equally over the two subsets and then over the models in each group. DeepL denotes the raw machine-translated version before author correction and localization.
Task
Prompt format
acc
acc_norm
acc_npsq
Ko-WinoGrande
plain
61.69
61.06
59.33
chat
58.08
57.64
55.73
Ko-LAMBADA
plain
92.49
92.13
87.39
chat
81.22
80.06
69.20
Ko-ARC-Easy
plain
67.81
69.04
71.21
chat
64.33
62.04
64.15
Table 4: Mean multiple-choice accuracy of open-weight models under three scoring rules: raw log-likelihood ( acc ), byte-length normalized log-likelihood ( acc_norm ), and NPSQ-based accuracy ( acc_npsq ).
Figure 3: Performance of Qwen3.5 Base (pretrained) and instruction-tuned variants at five paired model sizes under plain prompting. We report NPSQ accuracy for MCQA, strict exact match for Ko-GSM8K, prompt-level strict accuracy for Ko-IFEval, and the EQ-Bench score for Ko-EQ-Bench. Accuracies are expressed as percentages. 35B denotes 35B-A3B.
Ko-GSM8K
Ko-EQ-Bench
Qwen3.5
Default
Off
Default
Off
0.8B
23.05
23.96
16.77
16.65
2B
43.06
44.50
31.16
30.98
4B
0.15
69.60
0.00
53.11
9B
0.00
77.33
0.00
54.55
27B
0.00
80.67
0.00
72.47
Table 5: Qwen3.5 results under default chat prompting and with thinking disabled (Off). Ko-GSM8K reports strict exact match (%). Ko-EQ-Bench reports the EQ-Bench score. Both conditions use chat templates.
Task
Best open
Best closed
Gap
Ko-ARC-Easy
98.06
99.12
1.06
Ko-ARC-Challenge
96.57
97.77
1.20
Ko-LAMBADA
96.14
98.76
2.62
Ko-WinoGrande
84.85
93.37
8.52
Table 6: Best generative MCQA accuracy (%) among open-weight and closed API models under default chat configurations. Gemma-4-31B-it leads the open-weight group on all four tasks. GPT-5.5 leads the closed group on Ko-ARC-Challenge and Claude Opus 4.7 on the other tasks. Gap denotes the accuracy difference (closed minus open), in percentage points. Qwen non-thinking runs are reported separately in Appendix F .
Appendix figures & tables13 assets
Supplementary material from the paper’s appendix.
Appendix
Category
Original context in English ARC
Localized context in Ko-ARC
Locations
U.S. states, national parks, coastlines, and rivers
Korean or East Asian locations with analogous phenomena (e.g., U.S. Gulf coast → West Sea / Yellow Sea; Maine solar-noon example → Baengnyeongdo Island). Globally familiar references, such as the Himalayas, are retained when they are already standard in Korean science education.
Climate and seasonality
Hurricanes; jet-stream examples set in the continental U.S.
Comparable weather and seasonal phenomena in the Northwest Pacific (e.g., hurricanes → typhoons ; jet-stream examples rewritten using Korean winter-weather patterns; daylight-duration comparisons are rewritten using Korean cities with appropriate latitude differences).
Species and organisms
Black bear; warbler migration; Gulf sturgeon
Ecologically comparable species that are familiar in Korean educational contexts (e.g., Asiatic black bear in Jirisan Mountain; cranes migrating between Siberia or Manchuria and the Korean peninsula; salmon as a river-sea migratory species).
Industry and energy
Kentucky coal-transport context; U.S. 2003 electricity generation mix
Korean settings with comparable industrial or energy-related roles (e.g., Jecheon-si cement freight corridor; Korean 2022 electricity generation mix).
Units and measurements
Imperial units; city-by-city daylight comparisons
Metric units; numerical values adjusted when needed to preserve the scientific relation; city pairs reselected within Korea.
Everyday objects and cultural examples
U.S.-specific household or cultural items used to frame the question
Korean counterparts that make the question natural in Korean while preserving the scientific framing and the correct answer.
Appendix
Table 7: Representative localization rules for Ko-ARC. Each substitution is checked to preserve both the underlying scientific mechanism and the correct answer.
Instruction group
IFEval
Ko-IFEval
Changes
Keywords
4
6
Alphabet-based letter constraints are separated from Korean choseong(초성; leading consonant)-based constraints; a keyword-substitution check is added for Korean prompts.
Length Constraints
4
6
Character-count checks are extended to distinguish whitespace-inclusive and whitespace-exclusive counting, which is necessary for Korean spacing conventions.
Detectable Format
6
7
A multiple-choice formatting check is added.
Language
1
1
No structural change; the required response language can be Korean or English.
Detectable Content
2
2
No structural change.
Combination
2
2
No structural change.
Appendix
Table 8: Instruction-type inventory in the original IFEval and Ko-IFEval. The "Changes" column summarizes Ko-IFEval-specific additions and adaptations.
Dataset
Aligned items
Correction
Localization
Cross-review
Ko-ARC-Easy
2,376
2,056 (86.5%)
643 (27.1%)
72 (3.0%)
Ko-ARC-Challenge
1,172
720 (61.4%)
73 (6.2%)
42 (3.6%)
Ko-GSM8K
1,319
1,291 (97.9%)
830 (62.9%)
358 (27.1%)
Ko-EQ-Bench
171
171 (100.0%)
165 (96.5%)
14 (8.2%)
Appendix
Table 9: Recorded item revisions at each construction stage, reported as counts and percentages of aligned items. Ko-ARC-Challenge statistics cover the 1,172-item review pool before five items were excluded from the final dataset. The separate Ko-IFEval process is not included.
Provider
Model
Size
Hugging Face checkpoint
Korean-developed LLMs
KT
Mi:dm 2.0 Mini
2.3B
K-intelligence/Midm-2.0-Mini-Instruct
Mi:dm 2.0 Base
11.5B
K-intelligence/Midm-2.0-Base-Instruct
LG
EXAONE-4.0-1.2B
1.2B
LGAI-EXAONE/EXAONE-4.0-1.2B
EXAONE-4.0-32B
32B
LGAI-EXAONE/EXAONE-4.0-32B
Kakao
Kanana-2-30b-a3b-base-2601
30B-A3B
kakaocorp/kanana-2-30b-a3b-base-2601
Appendix
Table 10: Open-weight models evaluated. Sizes are reported in billions of parameters. For mixture-of-experts models, we also include the active-parameter shorthand reported by the developer, such as 30B-A3B . All checkpoints are accessed through the Hugging Face Hub.
Task
Few-shot
Output type
Max gen. toks
Metric
Ko-ARC-Easy
5
multiple choice
–
acc / acc_norm / acc_npsq
Ko-ARC-Challenge
5
multiple choice
–
acc / acc_norm / acc_npsq
Ko-WinoGrande
0
multiple choice
–
acc / acc_norm / acc_npsq
Ko-LAMBADA
0
multiple choice
–
acc / acc_norm / acc_npsq
Ko-GSM8K
5
generate-until
2048
strict-match / flexible-extract
Ko-IFEval
0
generate-until
1280
prompt-level and instruction-level strict/loose accuracy
Appendix
Table 11: Detailed task configuration. Original multiple-choice tasks are evaluated only for open-weight models with log-likelihood access. Generative multiple-choice variants are used for both open-weight and closed API models. For Ko-EQ-Bench, the maximum generation length is 80 tokens for open-weight models and 1024 tokens for closed API models.
Ko-WinoGrande
Ko-LAMBADA
Ko-ARC-Easy
Ko-ARC-Challenge
Model
Parameter size
acc
acc _norm
acc _npsq
acc
acc _norm
acc _npsq
acc
acc _norm
acc _npsq
acc
acc _norm
acc _npsq
HyperCLOVAX-SEED-Text- Instruct-0.5B
0.5B
55.72
55.88
54.62
93.30
92.95
87.72
58.71
58.67
61.66
32.39
38.73
38.05
HyperCLOVAX-SEED-Text- Instruct-1.5B
1.5B
56.83
57.06
54.70
90.02
89.22
84.17
60.35
61.45
59.51
34.53
40.62
38.13
A.X 4.0 Light
7B
64.96
63.38
62.75
96.59
96.32
93.13
78.41
78.87
79.46
55.87
59.73
61.27
Mi:dm 2.0 Mini
2.3B
61.25
60.62
58.80
96.76
96.54
93.48
75.55
76.60
78.11
48.33
54.84
58.70
Mi:dm 2.0 Base
11.5B
66.22
65.04
63.69
98.32
98.18
96.72
81.57
82.66
85.23
58.78
64.18
65.55
Appendix
Table 12: Open-weight multiple-choice results under plain prompting. The chat-template subset average uses the same model subset as the chat-template prompting results in Table 13 . The highest score in each metric column is highlighted in red.
Ko-WinoGrande
Ko-LAMBADA
Ko-ARC-Easy
Ko-ARC-Challenge
Model
Parameter size
acc
acc _norm
acc _npsq
acc
acc _norm
acc _npsq
acc
acc _norm
acc _npsq
acc
acc _norm
acc _npsq
HyperCLOVAX-SEED-Text -Instruct-0.5B
0.5B
55.49
55.09
54.85
83.99
83.19
74.99
55.56
55.60
57.74
31.19
36.59
35.48
HyperCLOVAX-SEED-Text -Instruct-1.5B
1.5B
57.46
56.35
55.09
83.86
83.55
78.76
57.91
59.72
58.88
33.25
40.19
37.45
A.X 4.0 Light
7B
58.72
59.12
57.77
86.56
85.81
78.49
75.46
77.15
77.36
50.64
56.56
56.47
Mi:dm 2.0 Mini
2.3B
59.67
58.49
54.78
83.55
81.82
66.83
72.39
73.70
75.25
45.59
52.19
51.76
Mi:dm 2.0 Base
11.5B
64.33
63.06
60.62
86.43
85.06
68.65
77.53
74.45
79.59
54.67
58.61
61.70
Appendix
Table 13: Open-weight multiple-choice results under chat-template prompting. The highest score in each metric column is highlighted in red.
Ko-GSM8K
Ko-IFEval
Ko-EQ-Bench
Model
Parameter size
strict -match
flexible -extract
prompt _level _strict _acc
inst _level _strict _acc
prompt _level _loose _acc
inst _level _loose _acc
eqbench
percent _parseable
HyperCLOVAX-SEED-Text-Instruct-0.5B
0.5B
4.09
3.79
12.49
25.99
14.63
29.06
7.90
89.47
HyperCLOVAX-SEED-Text-Instruct-1.5B
1.5B
9.40
7.88
21.64
36.72
23.54
39.44
38.99
92.98
A.X 4.0 Light
7B
78.85
78.92
60.29
74.36
65.16
77.56
54.53
100.00
Mi:dm 2.0 Mini
2.3B
57.85
61.71
19.62
29.13
24.26
32.96
11.93
38.01
Mi:dm 2.0 Base
11.5B
81.73
81.80
28.30
40.70
31.87
43.83
51.01
94.15
Appendix
Table 14: Open-weight generation results under plain prompting. The chat-template subset average uses the same model subset as the chat-template prompting results in Table 15 . The highest score in each metric column is highlighted in red.
Ko-GSM8K
Ko-IFEval
Ko-EQ-Bench
Model
Parameter size
strict -match
flexible -extract
prompt _level _strict _acc
inst _level _strict _acc
prompt _level _loose _acc
inst _level _loose _acc
eqbench
percent _parseable
HyperCLOVAX-SEED-Text-Instruct-0.5B
0.5B
3.56
6.07
17.48
32.33
18.79
34.49
25.99
95.91
HyperCLOVAX-SEED-Text-Instruct-1.5B
1.5B
12.51
11.90
22.24
36.31
24.38
39.23
41.32
93.57
A.X 4.0 Light
7B
82.18
82.34
73.72
83.07
76.10
85.09
56.04
100.00
Mi:dm 2.0 Mini
2.3B
66.03
67.32
53.98
65.78
57.67
68.43
16.30
46.20
Mi:dm 2.0 Base
11.5B
32.60
84.08
70.15
80.63
74.79
83.76
47.32
78.95
Appendix
Table 15: Open-weight generation results under chat-template prompting. The highest score in each metric column is highlighted in red.
Model
Ko -WinoGrande -gen
Ko -LAMBADA -gen
Ko-ARC -Easy -gen
Ko-ARC -Challenge -gen
Ko-GSM8K
Ko-IFEval
Ko-EQ-Bench
exact _match
exact _match
exact _match
exact _match
strict _match
flexible _extract
prompt _level _strict _acc
inst _level _strict _acc
prompt _level _loose _acc
inst _level _loose _acc
eqbench
percent _parseable
Claude Haiku 4.5
77.82
91.8
97.9
94.17
93.48
93.48
71.7
82.37
81.45
88.5
65.79
98.25
Claude Opus 4.7
93.37
98.76
99.12
97.17
96.06
96.06
79.55
87.25
83.47
89.69
79.23
100
GPT-5-mini
76.95
64.66
97.69
95.89
81.96
94.47
36.98
35.75
37.1
35.82
64.9
99.42
GPT-5.5
91.71
96.63
98.91
97.77
96.29
96.29
81.09
83.69
82.16
84.39
78.71
100
Appendix
Table 16: Closed API model results across all benchmark tasks under chat-style prompting.
Ko-WinoGrande-gen
Ko-LAMBADA-gen
Ko-ARC-Easy-gen
Ko-ARC-Challenge-gen
Model
Parameter size
exact_match
exact_match
exact_match
exact_match
HyperCLOVAX-SEED-Text-Instruct-0.5B
0.5B
22.18
3.90
66.71
49.44
HyperCLOVAX-SEED-Text-Instruct-1.5B
1.5B
48.38
61.02
76.01
58.35
A.X 4.0 Light
7B
67.25
85.90
93.22
86.38
Mi:dm 2.0 Mini
2.3B
57.70
74.19
84.51
73.09
Mi:dm 2.0 Base
11.5B
68.19
86.65
94.23
87.06
Appendix
Table 17: Generative MCQA results for open-weight models under chat-style prompting. The highest score in each metric column is highlighted in red.
Model
Parameter size
Ko -WinoGrande -gen
Ko -LAMBADA -gen
Ko-ARC -Easy -gen
Ko-ARC -Challenge -gen
Ko-GSM8K
Ko-EQ-Bench
exact _match
exact _match
exact _match
exact _match
strict _match
flexible _extract
eqbench
percent _parseable
Qwen3.5-0.8B
0.8B
50.12
51.71
62.58
50.64
23.96
25.17
16.65
99.42
Qwen3.5-2B
2B
38.20
55.17
81.57
69.75
44.50
45.34
30.98
100.00
Qwen3.5-4B
4B
62.51
81.37
93.52
86.89
69.60
71.04
53.11
100.00
Qwen3.5-9B
9B
68.19
87.01
96.34
91.09
77.33
78.54
54.55
100.00
Qwen3.5-27B
27B
80.58
95.92
98.53
96.06
80.67
82.87
72.47
100.00
Appendix
Table 18: Generative MCQA and generation results for six instruction-tuned Qwen3.5 models with enable_thinking=False , while retaining chat templates.
Task
Model group
English
DeepL
KBS
ARC
Korean-developed
67.29
54.00
59.49
Qwen3.5
51.22
44.14
46.49
Gemma 4
72.56
60.14
67.05
GSM8K
Korean-developed
57.52
34.36
44.80
Qwen3.5
54.11
10.01
11.06
Gemma 4
82.41
59.84
64.48
Appendix
Table 19: Performance across English, raw DeepL, and KBS variants under chat-style prompting, averaged over the same eight Korean-developed, six Qwen3.5, and four Gemma 4 models. ARC and WinoGrande use NPSQ accuracy, GSM8K uses strict exact match, and EQ-Bench uses its benchmark score. DeepL results are unavailable for WinoGrande and excluded for EQ-Bench because the Korean emotion labels in the translated prompts do not match the English reference labels used by the scorer.
Multimodal evaluation is strengthened when benchmarks reflect the languages, institutions, and disciplinary conventions that shape expert visual reasoning. We introduce KMMMU, a native Korean benchmark built from Korean-native examination materials. KMMMU contains 3,466 questions spanning nine disciplines and nine visual modality categories. For targeted evaluation on challenging questions and Korean-specific knowledge, we additionally provide KMMMU-Adv and KMMMU-Local, respectively. Experiments show that the strongest evaluated open-weight model reaches 42.05% on the KMMMU, while the best evaluated proprietary model achieves 52.42% on the KMMMU-Adv. Performance varies substantially across disciplines and answer formats, with Korean-specific questions showing gaps of up to 13.43%. Error analysis suggests that inspected failures often involve convention-to-label mapping, few-shot symbolic induction, localized knowledge recall, and domain-specific standards, not reasoning depth alone. KMMMU provides a testbed for native Korean expert-level multimodal understanding beyond English-centric or translation-based evaluation.
Nahyun Lee, Guijin Son, Hyunwoo Ko +4
Chung-Ang University · HAE-RAE · Seoul National University +2
Recent advances in large audio language models (LALMs) have enabled multilingual speech understanding. However, benchmarks for evaluating LALMs remain scarce for non-English languages, with Korean being one such underexplored case. In this paper, we introduce KoALa-Bench, a comprehensive benchmark for evaluating Korean speech understanding and speech faithfulness of LALMs. In particular, KoALa-Bench comprises six tasks. Four tasks evaluate fundamental speech understanding capabilities, including automatic speech recognition, speech translation, speech question answering, and speech instruction following, while the remaining two tasks evaluate speech faithfulness, motivated by our observation that several LALMs often fail to fully leverage the speech modality. Furthermore, to reflect Korea-specific knowledge, our benchmark incorporates listening questions from the Korean college scholastic ability test as well as content covering Korean cultural domains. We conduct extensive experiments across six models, including both white-box and black-box ones. Our benchmark, evaluation code, and leaderboard are publicly available at https://ksbench.github.io/Korean-Benchmark/.
Jinyoung Kim, Hyeongsoo Lim, Eunseo Seo +4
Department of Artificial Intelligence, Chung-Ang University · Upstage AI
Selecting a pretrained language model, or evaluating a fine-tuned one, for a specific application is a high-value decision, yet the public benchmarks used to make it are poorly suited: a generic benchmark need not reflect a particular sub-domain or sub-task, and its scores are suspect when its items have leaked into pretraining and are recalled rather than solved. We present CoEval, an open framework that supplies a trustworthy, task-specific signal through ensemble self-evaluation: from a task or domain description, a pool of models rotates through all three roles, teacher, student, and judge, to generate a fresh, contamination-free benchmark, answer it, and score one another, with no human labels or raters. Because every model also answers as a student, the responses are the data that weight each question by its discriminative power and each judge by its consensus with the panel. Where ground truth exists, CoEval recovers the true ranking and tracks objective correctness at \r{ho}=0.86, and the weighting recovers the gold ranking of thirteen models at Spearman 0.95. Reliability comes from panel composition, not size: this label-free weighting zeroes out broken judges and down-weights saturated questions, so neither distorts the ranking. Generated items show zero verbatim overlap with five public benchmarks, the panel cancels verbosity bias and precludes same-family self-preference, and rankings are domain-specific: three different models top four de-novo domains, so a generic leaderboard misdirects most practitioners. The same pipeline reruns on each model release, giving any team a contamination-free leaderboard for its application.
Alexander Apartsin, Yehudit Aperstein
Holon Institute of Technology, Israel · Afeka Tel Aviv Academic College of Engineering, Israel