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Performance Improvement of a Korean Open Domain Q&A System by Applying the Trainable Re-ranking and Response Filtering Model
Hyeonho Shin, Myunghoon Lee, Hong-Woo Chun, Jae-Min Lee, Sung-Pil Choi
http://doi.org/10.5626/JOK.2023.50.3.273
Research on Open Domain Q&A, which can identify answers to user inquiries without preparing the target paragraph in advance, is currently being undertaken as deep learning technology is used for natural language processing. However, existing studies have limitations in semantic matching using keyword-based information retrieval. To supplement this, deep learning-based information retrieval research is in progress. But there are not many domestic studies that have been empirically applied to real systems. In this paper, a two-step performance enhancement method was proposed to improve the performance of the Korean open domain Q&A system. The proposed method is a method of sequentially applying a machine learning-based re-ranking model and a response filtering model to a baseline system in which a search engine and an MRC model was combined. In the case of the baseline system, the initial performance was an F1 score of 74.43 and an EM score of 60.79, and it was confirmed that the performance improved to an F1 score of 82.5 and an EM score of 68.82 when the proposed method was used.
BERT-based Two-Stage Classification Models and Co-Attention Mechanism for Diagnosing Dementia and Schizophrenia-related Disease
Min-Kyo Jung, Seung-Hoon Na, Ko Woon Kim, Byoung-Soo Shin, Young-Chul Chung
http://doi.org/10.5626/JOK.2022.49.12.1071
Noting the recently increasing number of patients, we present deep learning methods for automatically diagnosing dementia and schizophrenia by exploring the use of the novel two-stage classification and the co-attention mechanism. First, the two-stage classification consists of two steps-the perplexity-based classification and the standard BERT-based classification. 1) the perplexity-based classification first prepares two types of BERTs, i.e., control-specific and patients-specific BERTs, pretrained from transcripts for controls and patients as the additional pretraining datasets, respectively, and then performs a simple threshold-based classification based on the difference between perplexity values of two BERTs for an input test transcript; then, for ambiguous cases where the perplexity difference only does not provide sufficient evidence for the classification, the standard BERT-based classification is performed based on a fine-tuned BERT. Second, the co-attention mechanism enriches the BERT-based representations from a doctor’s transcript and a client’s one by applying the cross-attention over them using the shared affinity matrix, and performs the classification based on the enriched co-attentive representations. Experiment results on a large-scale dataset of Korean transcripts show that the proposed two-stage classification outperforms the baseline BERT model on 4 out of 7 subtasks and the use of the co-attention mechanism achieves the best F1 score for 4 out of 8 subtasks.
Solving Korean Math Word Problems Using the Graph and Tree Structure
Kwang Ho Bae, Sang Yeop Yeo, Yu Chul Jung
http://doi.org/10.5626/JOK.2022.49.11.972
In previous studies, there have been various efforts to solve math word problems in the English sentence system. In many studies, improved performance was achieved by introducing structures such as trees and graphs, beyond the Sequence-to-Sequence approaches. However, in the study of solving math problems in Korean sentence systems, there are no model cases, using structures such as trees or graphs. Thus, in this paper, we examine the possibility of solving math problems in Korean sentence systems for models using the tree structure, graph structure, and Korean pre-training language models together. Our experimental results showed that accuracy improved by approximately 20%, compared to the model of the Seq2seq structure, by introducing the graph and tree structure. Additionally, the use of the Korean pre-training language model showed an accuracy improvement of 4.66%-5.96%.
KorSciQA 2.0: Question Answering Dataset for Machine Reading Comprehension of Korean Papers in Science & Technology Domain
Hyesoo Kong, Hwamook Yoon, Mihwan Hyun, Hyejin Lee, Jaewook Seol
http://doi.org/10.5626/JOK.2022.49.9.686
Recently, the performance of the Machine Reading Comprehension(MRC) system has been increased through various open-ended Question Answering(QA) task, and challenging QA task which has to comprehensively understand multiple text paragraphs and make discrete inferences is being released to train more intelligent MRC systems. However, due to the absence of a QA dataset for complex reasoning to understand academic information in Korean, MRC research on academic papers has been limited. In this paper, we constructed a QA dataset, KorSciQA 2.0, for the full text including abstracts of Korean academic papers and divided the difficulty level into general, easy, and hard for discriminative MRC systems. A methodology, process, and system for constructing KorSciQA 2.0 were proposed. We conducted MRC performance evaluation experiments and when fine-tuning based on the KorSciBERT model, which is a Korean-based BERT model for science and technology domains, the F1 score was 80.76%, showing the highest performance.
Evaluating of Korean Machine Reading Comprehension Generalization Performance via Cross-, Blind and Open-Domain QA Dataset Assessment
http://doi.org/10.5626/JOK.2021.48.3.275
Machine reading comprehension (MRC) entails identification of the correct answer in a paragraph when a natural language question and paragraph are provided. Recently, fine-tuning based on a pre-trained language model yields the best performance. In this study, we evaluated the ability of machine-reading comprehension method to generalize question and paragraph pairs, rather than similar training sets. Towards this end, the cross-evaluation between datasets and blind evaluation was performed. The results showed a correlation between generalization performance and datasets such as answer length and overlap ratio between question and paragraph. As a result of blind evaluation, the evaluation dataset with the long answer and low lexical overlap between the questions and paragraphs resulted in less than 80% performance. Finally, the generalized performance of the MRC model under the open domain QA environment was evaluated, and the performance of the MRC using the searched paragraph was found to be degraded. According to the MRC task characteristics, the difficulty and differences in generalization performance depend on the relationship between the question and the answer, suggesting the need for analysis of different evaluation sets.
Korean Dependency Parsing using Token-Level Contextual Representation in Pre-trained Language Model
http://doi.org/10.5626/JOK.2021.48.1.27
Dependency parsing is a problem of disambiguating sentence structure by recognizing dependencies and labels between words in sentences. In contrast to previous studies that have applied additional RNNs to the pre-trained language model, this paper proposes a dependency parsing method that uses fine-tuning alone to maximize the self-attention mechanism of the pre-trained language model, and also proposes a technique for using relative distance parameters and SEP tokens. In the results of evaluating the Sejong parsing corpus of TTA standard guidelines, the KorBERT_base model showed 95.73% UAS and 93.39% LAS while the KorBERT_large model showed 96.31% UAS and 94.17% LAS. This represents an improvement of about 3% compared to the results of previous studies that did not use the pre-trained language model. Next, the results of the word-morpheme mixed transformation corpus of the previous study showed that the KorBERT_base model was 94.19% UAS and that the KorBERT_large model was 94.76% UAS.
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