LD
Ph.D. in Applied Linguistics · Georgia State University

LanguageasDataLab

Led by Youngmeen Kim, Ph.D.
Second Language Acquisition

Corpus linguistics and interpretable machine learning, surfacing behavioral patterns in learner language, mental health discourse, legal text, and human-AI interaction.

People use language differently.

Peopleuselanguagedifferently.

The differences are measurable.

Language as Data Lab · Youngmeen Kim, Ph.D.

Impact

Research in the World

Full impact
NBC 11Alive · 2025GSU Newsroom · 2025Phys.org · 2025The Korea Times Atlanta · 2025Atlanta JoongAng Daily · 2025Keynote · Univ. of North Georgia · 2024Invited · KAMALL · 2024AAAL 2025 · DenverAACL 2024 · OregonCALICO 2025 · San DiegoTBLT 2025 · GroningenRMAL · 2026Corpus-based Studies · 2025
Media · 2025

NBC 11Alive

Television and online coverage of AI-based detection of depression-related language in online communities.

Media · 2025

GSU Newsroom & Phys.org

University and science-press features: AI can spot signs of depression in Reddit posts.

Keynote · 2024

Keynote · Univ. of North Georgia

Keynote at the Linguistics Symposium on automatic language evaluation using machine learning and LLMs.

Conference · 2025

AAAL 2025 · Denver

Machine-learning and corpus-analytic comparison of language use across online mental health communities.

Publication · 2026

Research Methods in Applied Linguistics

The power of the prompt: the linguistic effects of prompt engineering on GenAI and learners.

Engineering · 2023–2025

GenAI Learner Platform

Built a GenAI human-computer interaction system with TTS and STT for recently immigrated English learners.

The Research Pipeline

From Language
to Insight

A scroll through the pipeline that turns raw text into interpretable findings.

01
Illustrative example

Raw Language Data

Where it all begins

Real-world text: posts from online mental health communities, learner essays, legal documents, chatbot exchanges. Language in the wild is unstructured, contextual, and rich with behavioral signal.

Online community post

"I can't focus on anything lately. The worrynever really switches off."

Legal document

"The parties shall perform all obligationsset forth in this agreement."

Learner essay

"My writingimproves every semester but articles are still hard for me."

Online CommunitiesLegal DocumentsLearner Corpora
02
Illustrative example

Linguistic Feature Extraction

Structure beneath the surface

Tokenization, POS tagging, dependency parsing, and collocation analysis. Corpus tools turn text into measurable features: lexical sophistication, syntactic complexity, frequency profiles.

Part-of-speech tagging

NNLanguagensubj
VBZreflectsROOT
JJhumanamod
NNSmindsdobj

Collocational strength

worry + constant
sleep + trouble
feel + alone
spaCyNLTKPOS TaggingDependency Parse
03

Contextual Embeddings

Meaning becomes geometry

BERT and sentence transformers encode words and sentences as high-dimensional vectors. Semantically similar language clusters together, making distance and difference measurable.

PCA projection of all-MiniLM-L6-v2 embeddings (precomputed)

learneracquisitionproficiencyfluencyaccuracyvocabularygrammarwritingcorpusfrequencycollocationconcordancekeywordtokenlemmaanxietydepressionstressmoodtherapywellbeingstatutecontractcourtevidencetestimonyclausetheofandbutwithfrombecauseif
Hover or tap a word: top-3 nearest neighbors by cosine similarity.
Learner languageCorpus termsMental healthLegalFunction words
BERTSentence TransformersPCA
04

Statistical & Machine Learning

Modeling at corpus scale

Mixed-effects regression and structural equation modeling estimate effects and relationships; classical and deep classifiers learn to predict from linguistic features. Both are evaluated at corpus scale.

Classification accuracy

Support Vector Machine95.74%

As reported in Kim & Römer-Barron (2025), Corpus-based Studies across Humanities, 3(2).

Mixed-effectsSEMSVMXGBoost
05
Illustrative example

Explainable AI

Opening the black box

SHAP, LIME, permutation importance, and feature ablation reveal which linguistic features drive each prediction.

Feature attribution

1st-person sg.
negative affect
social words
present focus
SHAPLIMEPermutation Importance
06

Linguistic Insight

Model behavior becomes evidence

Explained predictions become linguistic findings that can be checked against the corpus and stated in the language of the discipline.

Published finding

Depression-related language in an online community can be detected and analyzed with machine learning, topic modeling, and corpus-linguistic approaches.

Kim & Römer-Barron (2025) · doi:10.1515/csh-2025-0005

Corpus VerificationTopic Modeling
07

Interpretation & Theory

Features, not black boxes, carry the explanation

Findings are mapped back to linguistic theory. The result is a claim a linguist can interrogate, not just a score.

From model to theory

linguistic findinglinguistic theoryinterpretable claim
Dynamic Systems TheoryPsycholinguistics
Methodology

How I Study Language

Quantitative modeling paired with qualitative linguistic analysis: patterns are measured at scale and interpreted through linguistic theory.

Research

Research Streams

Corpus linguistics and machine learning applied where language carries evidence about people: mental health, language learning, law, and human-AI interaction.

Mental health language

Published 2025

Machine learning, topic modeling, and corpus-linguistic analysis of depression-related language in online communities, the core of my dissertation research.

Corpus-based Studies across Humanities (2025) · PTSD/anxiety study in preparation

machine learningtopic modelingcorpus linguistics

L2 development & learner language

Published 2023 · 2 under review

Tracing collocation use, readability, and cohesion across proficiency levels with interpretable machine learning on learner corpora.

ELLIPSE Corpus, IJLCR (2023) · Applied Linguistics & Applied Corpus Linguistics (under review)

learner corporacollocationreadability

Legal linguistics & NLP

2023 – 2026

Advising J.D. candidates on NLP tools and corpus-linguistic approaches to the interpretation of U.S. legal documents.

Georgia State University College of Law · research advisory roles

legal NLPcorpus methods

Generative AI for language learners

Funded · Published 2026

Building GenAI-based interaction systems, chatbots with TTS and STT, for recently immigrated English learners, and studying their linguistic effects.

Research Methods in Applied Linguistics (2026) · RCALL seed grant ($48,500) · Cambridge English Funded Research Programme (FRP), £13,000

GenAITTS/STTalignment
Publications

Published Work

2026Published

The power of the prompt: The linguistic effects of prompt engineering on GenAI and learners

Dixon, D. H., Kim, YJ., & Kim, Y.

Research Methods in Applied Linguistics, 5(2), Article 100327.

doi:10.1016/j.rmal.2026.100327
2025Published

Detection and analysis of depression-related language in an online community: Machine learning, topic modeling, and corpus-linguistic approaches

Kim, Y. & Römer-Barron, U.

Corpus-based Studies across Humanities, 3(2), 283–312.

doi:10.1515/csh-2025-0005
2023Published

The English Language Learner Insight, Proficiency and Skills Evaluation (ELLIPSE) Corpus

Crossley, S., Tian, Y., Baffour, P., Franklin, A., Kim, Y., Morris, W., Benner, M., Picou, A., & Boser, U.

International Journal of Learner Corpus Research, 9(2), 248–269.

doi:10.1075/ijlcr.22026.cro

Plus 2 manuscripts under review and 2 in preparation. All publications

Teaching

Courses Taught

CourseInstitutionPeriod
Language in SocietyGeorgia State UniversityJanuary 2026May 2026
Introduction to English LinguisticsGeorgia State UniversityAugust 2025December 2025
Introduction to LinguisticsGeorgia State UniversityJanuary 2025May 2025
Introduction to English LinguisticsGeorgia State UniversityJune 2024August 2024
Introduction to LinguisticsGeorgia State UniversityJanuary 2024May 2024
Linguistic Interpretation and Investigation of U.S. Legal DocumentsGeorgia State UniversityJanuary 2023May 2024

Teaching Approach

I teach linguistics as a data-driven discipline. Whether the course is Introduction to Linguistics or Language in Society, students work with real language data and learn to turn observation into evidence. My aim is for students to leave the course able to ask precise questions about language and to answer them with data.

Teaching Record

University teaching from 2021 to 2026: linguistics courses and legal-linguistics support at Georgia State University, and Korean language instruction.

View all teaching
Tools & Demos

Lab Tools

Real linguistic feature extraction you can run yourself. Every tool is computationally correct, honestly labeled, and cited.

All tools

Lexical & Cohesion Analyzer

Live

Lexical diversity (TTR, MATTR, MTLD, HD-D), lexical density, n-grams, and cohesion indices on any text, computed in your browser.

Semantic Similarity Explorer

Live

Transformer sentence embeddings, cosine similarity, a 2-D projection, and a token-level similarity heatmap, all in-browser.

Syntactic Parsing & Complexity

Live

POS tagging and dependency parsing with arc visualizations, plus live dependency-based complexity: tree depth and mean dependency distance.