• Journal of the Korean Institute of Intelligent Systems
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• v.25 no.2
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• pp.180-185
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• 2015

As the number of document resources is continuously increasing, automatically extracting keyphrases from a document becomes one of the main issues in recent days. However, most previous works have tried to extract keyphrases from words in documents, so they overlooked latent keyphrases which did not appear in documents. Although latent keyphrases do not appear in documents, they can undertake an important role in text summarization and information retrieval because they implicate meaningful concepts or contents of documents. Also, they cover more than one fourth of the entire keyphrases in the real-world datasets and they can be utilized in short articles such as SNS which rarely have explicit keyphrases. In this paper, we propose a new approach that selects candidate keyphrases from the keyphrases of neighbor documents which are similar to the given document and evaluates the importance of the candidates with the individual words in the candidates. Experiment result shows that latent keyphrases can be extracted at a reasonable level.

• Journal of Information Science Theory and Practice
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• v.2 no.1
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• pp.6-21
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• 2014

This paper proposes a novel knowledge extraction system, TAKES (Two-step Approach for Knowledge Extraction System), which integrates advanced techniques from Information Retrieval (IR), Information Extraction (IE), and Natural Language Processing (NLP). In particular, TAKES adopts a novel keyphrase extraction-based query expansion technique to collect promising documents. It also uses a Conditional Random Field-based machine learning technique to extract important biological entities and relations. TAKES is applied to biological knowledge extraction, particularly retrieving promising documents that contain Protein-Protein Interaction (PPI) and extracting PPI pairs. TAKES consists of two major components: DocSpotter, which is used to query and retrieve promising documents for extraction, and a Conditional Random Field (CRF)-based entity extraction component known as FCRF. The present paper investigated research problems addressing the issues with a knowledge extraction system and conducted a series of experiments to test our hypotheses. The findings from the experiments are as follows: First, the author verified, using three different test collections to measure the performance of our query expansion technique, that DocSpotter is robust and highly accurate when compared to Okapi BM25 and SLIPPER. Second, the author verified that our relation extraction algorithm, FCRF, is highly accurate in terms of F-Measure compared to four other competitive extraction algorithms: Support Vector Machine, Maximum Entropy, Single POS HMM, and Rapier.

• Annual Conference on Human and Language Technology
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• 2018.10a
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• pp.176-178
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• 2018

트위터는 최대 140자의 단문을 주고받는 소셜 네트워크 서비스이다. 트위터의 해시 태그는 주로 문장의 핵심 단어나 주요 토픽 등을 링크하게 되는데 본 논문에서는 이러한 정보를 이용하여 키워드 추출에 활용한다. 문장을 Character CNN, Bi-LSTM을 통해 문장 표현을 얻어내고 각 Span에서 이러한 문장 표현을 활용하여 Span 표현을 생성한다. Span 표현을 이용하여 각 Span에 대한 Score를 얻고 높은 점수의 Span을 이용하여 키워드를 추출한다.

• Journal of KIISE:Software and Applications
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• v.36 no.5
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• pp.420-429
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• 2009

Patent text is a rich source for discovering technological trends. In order to automate such a discovery process, we attempt to identify phrases corresponding to the problem and its solution method which together form a technology. Problem and solution phrases are identified by a SVM classifier using features based on a combination of a language modeling approach and linguistic clues. Based on the occurrence statistics of the phrases, we identify the time span of each problem and solution and finally generate a trend. Based on our experiment, we show that the proposed semantic phrase identification method is promising with its accuracy being 77% in R-precision. We also show that the unsupervised method for discovering technological trends is meaningful.

• Proceedings of the Korean Information Science Society Conference
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• 2008.06c
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• pp.252-256
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• 2008

본 연구에서는 Active Learning의 학습과정을 변형하여 학습노력을 줄이고 성능향상을 이루는 방법에 대해서 기술한다. Active Learning을 사용하는 이유는 학습 코퍼스의 량을 줄이면서도 우수한 성능을 얻기 위해서이다. 우리는 학습량을 줄이기 위해서 다양성과 대표성이 높은 학습 데이터를 추가한다. 높은 다양성을 얻기 위해서 기 학습된 코퍼스와 가장 관련이 없는 데이터를 추가하고 높은 대표성을 얻기 위해 예제 군집화를 통해 대표적인 예제를 추가할 수 있도록 하였다. 제안된 방법의 효용성을 검사하기 위해서 고정키어구 추출 문제에 적용하였다. 실험결과를 보면 지도학습을 이용한 실험결과보다 우수하였으며, 학습량을 83%정도 줄일 수 있었다.

• Annual Conference on Human and Language Technology
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• 2019.10a
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• pp.241-245
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• 2019

문서 요약, 키프레이즈 추출과 패러프레이징은 인간이, 혹은 기계가 문서를 보다 원활히 이해하는 데에 도움을 주는 방법론들이다. 우리는 본 연구에서 질문/요구 등의 지시성 발화를 대상으로, 핵심 내용을 추출하는 간단한 방법론을 통해 한국어 병렬 코퍼스를 구축한다. 또한, 우리는 인적 자원을 활용한 효율적인 데이터 증강 전략을 통해 부족하거나 필수적인 유형의 발화의 양을 보강하고, 약 5만 쌍 크기의 코퍼스를 제작하여 이를 공개한다.

• Journal of Information Processing Systems
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• v.9 no.4
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• pp.602-620
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• 2013

Many previous research studies on extractive text summarization consider a subset of words in a document as keywords and use a sentence ranking function that ranks sentences based on their similarities with the list of extracted keywords. But the use of key concepts in automatic text summarization task has received less attention in literature on summarization. The proposed work uses key concepts identified from a document for creating a summary of the document. We view single-word or multi-word keyphrases of a document as the important concepts that a document elaborates on. Our work is based on the hypothesis that an extract is an elaboration of the important concepts to some permissible extent and it is controlled by the given summary length restriction. In other words, our method of text summarization chooses a subset of sentences from a document that maximizes the important concepts in the final summary. To allow diverse information in the summary, for each important concept, we select one sentence that is the best possible elaboration of the concept. Accordingly, the most important concept will contribute first to the summary, then to the second best concept, and so on. To prove the effectiveness of our proposed summarization method, we have compared it to some state-of-the art summarization systems and the results show that the proposed method outperforms the existing systems to which it is compared.

• Annual Conference on Human and Language Technology
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• 2020.10a
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• pp.357-362
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• 2020

자연어 처리 응용 시스템이 패러프레이즈 표현을 얼마나 정확하게 포착하는가에 따라 응용 시스템의 성능 측면에서 차이가 난다. 따라서 자연어 처리의 응용 분야 전반에서 패러프레이즈 표현에 대한 중요성이 커지고 있다. 시스템의 성능 향상을 위해서는 모델을 학습시킬 충분한 말뭉치가 필요하다. 특히 이러한 패러프레이즈 말뭉치를 구축하기 위해서는 정확한 패러프레이즈 추출이 필수적이다. 따라서 본 연구에서는 패러프레이즈를 추출을 위한 언어 자원으로 키프레이즈 데이터셋을 제안하고 이를 기반으로 유사한 의미를 전달하는 패러프레이즈 관계의 문장을 추출하였다. 구축한 키프레이즈 데이터셋을 패러프레이즈 추출에 활용한다면 본 연구에서 수행한 것과 같은 간단한 방법으로 패러프레이즈 관계에 있는 문장을 찾을 수 있다는 것을 보였다.

• Journal of the Korean Society for information Management
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• v.34 no.1
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• pp.177-195
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• 2017

This study attempts to infer research fronts using factor graph model based on heterogeneous features. The model suggested by this study infers research fronts having documents with the potential to be cited multiple times in the future. To this end, the documents are represented by bibliographic, network, and content features. Bibliographic features contain bibliographic information such as the number of authors, the number of institutions to which the authors belong, proceedings, the number of keywords the authors provide, funds, the number of references, the number of pages, and the journal impact factor. Network features include degree centrality, betweenness, and closeness among the document network. Content features include keywords from the title and abstract using keyphrase extraction techniques. The model learns these features of a publication and infers whether the document would be an RF using sum-product algorithm and junction tree algorithm on a factor graph. We experimentally demonstrate that when predicting RFs, the FG predicted more densely connected documents than those predicted by RFs constructed using a traditional bibliometric approach. Our results also indicate that FG-predicted documents exhibit stronger degrees of centrality and betweenness among RFs.