LD
Research

Research streams

My work applies corpus linguistics and machine learning across domains where language carries evidence about people: mental health, language learning, and law.

Streams

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

How I study language

Corpus linguistics

Large collections of real language use, analyzed systematically: frequency, collocation, keyness, and concordance methods that make claims about language verifiable at scale.

Natural language processing

Computational pipelines that turn raw text into linguistic features: tokenization, POS tagging, dependency parsing, embeddings, and psycholinguistic feature engineering.

Explainable AI

SHAP, LIME, permutation importance, and feature ablation, used to open black-box models and state findings in linguistic terms rather than model weights.

Funded projects

Generative AI for Supporting Recently Immigrated English Learners' Language Development through Alignment: The Role of Input Complexity and Learner Proficiency

Research on the Challenges of Acquiring Language & Literacy (RCALL) · Seed grants, Georgia State University · $48,500

YouJin Kim (PI) and Daniel Dixon (Co-PI) · May 2024 – May 2025

My role: Research Assistant, Software Developer, Georgia State University, Department of Applied Linguistics.

  • Developed Generative AI-based human-computer interaction system for language learners
  • Implemented Text-to-Speech, Speech-to-Text, and Speech-to-Speech functionalities to enhance human-computer interaction
  • Designed and managed data collection and developed NLP scripts for data analysis

Generative AI for Supporting Recently Immigrated English Learners' L2 Development through Alignment: The Role of Task Input Complexity and Interaction Modalities

Cambridge English Funded Research Programme (FRP) · £13,000

YouJin Kim (PI) and Daniel Dixon (Co-PI) · August 2023 – December 2023

My role: Research Assistant, Software Developer, Georgia State University, Department of Applied Linguistics.

  • Developed GPT-based chatbot designed to help the immigrant population
  • Designed NLP scripts for data analysis including measuring lexical sophistication, syntactic complexity, and large-language-model-based semantic alignment
  • Developed NLP scripts for collocation and semantic analysis

Methods & tooling

A curated summary of the computational toolkit behind this research.

Languages & Core Tools

Python and R across the full research pipeline.

PythonRspaCyNLTKScikit-learnTensorFlowPyTorch

Statistical Computing

From t-tests to structural equation modeling.

ANOVA / MANOVALinear mixed-effects modelsSEM & path analysisFactor analysis (CFA, EFA)Rasch model, DFA/MDA

Natural Language Processing

Feature engineering from raw text: contextual embeddings to classic corpus statistics.

BERTN-gram & TF-IDF vectorizationPOS tagging & dependency parsingPsycholinguistic feature engineeringSentiment analysis (VADER, EmoLex)

Machine Learning & Deep Learning

Classical models through deep sequence architectures, plus ensembling.

SVM, Logistic Regression, Elastic NetRandom Forest, XGBoost, CatBoostCNNs, RNNs, GRUs, LSTMs, TCNsTopic modeling (LDA, BERTopic)Ensembles (stacking, blending, voting)

Interpretable ML & Explainable AI

Opening black-box models from linguistic perspectives.

SHAPLIMEPermutation importanceFeature ablationCoefficient-based analysis

Performance & Optimization

GPU-accelerated workflows and principled tuning.

NVIDIA CUDARAPIDS (cuDF, cuML, cuPy)OptunaNSGA-II multi-objective optimizationImbalanced-data methods (SMOTE, NearMiss, ENN, NCR)

Research positions

Research Assistant · Georgia State University, College of LawJanuary 2026 – May 2026
  • Advising eleven Juris Doctor (J.D.) candidates in designing and conducting research for the course Linguistic Interpretation and Investigation of U.S. Legal Documents
Research Assistant, Software Developer · Georgia State University, Department of Applied LinguisticsMay 2024 – May 2025
  • Developed Generative AI-based human-computer interaction system for language learners
  • Implemented Text-to-Speech, Speech-to-Text, and Speech-to-Speech functionalities to enhance human-computer interaction
  • Designed and managed data collection and developed NLP scripts for data analysis
Research Assistant · Georgia State University, College of LawJanuary 2024 – May 2024
  • Advised six J.D. candidates on the use of NLP tools and corpus-linguistic approaches for the course Linguistic Interpretation and Investigation of U.S. Legal Documents
Research Assistant, Software Developer · Georgia State University, Department of Applied LinguisticsAugust 2023 – December 2023
  • Developed GPT-based chatbot designed to help the immigrant population
  • Designed NLP scripts for data analysis including measuring lexical sophistication, syntactic complexity, and large-language-model-based semantic alignment
  • Developed NLP scripts for collocation and semantic analysis
Research Assistant · Georgia State University, Department of World Languages and CulturesAugust 2022 – May 2023
  • Managed a virtual exchange program between Korean students and Georgia State University students
  • Conducted data collection and analysis of virtual interactions
Research Assistant · Georgia State University and The Learning AgencyMay 2021 – August 2022
  • Analyzed demographic data linked to writing samples from U.S. K-12 students
  • Performed data cleaning and preprocessing
  • Conducted bias and discrimination analyses
Research Assistant · Georgia State University, Department of Applied LinguisticsAugust 2020 – May 2021
  • Developed a new text readability formula using part-of-speech tags
  • Analyzed traditional readability formulas and the correlation between readability scores and human-based holistic readability ratings
  • Assisted in developing a machine learning-based readability formula
  • Examined the validity and reliability of the new readability formula
Research Assistant · Cha and Kim English Education Research Center, Seoul, KoreaMay 2017 – December 2018
  • Investigated the effects of an extensive reading program on undergraduate students
  • Designed and developed the extensive reading program
  • Managed research participants and analyzed data
Research Assistant · HUFS Education Center, Seoul, KoreaMay 2013 – December 2017
  • Conducted a longitudinal study examining factors influencing campus life adjustment and satisfaction
  • Collected data spanning four years from over 20,000 undergraduate students
  • Analyzed the relationship between admission types and academic performance, school adjustment, and other needs