The KIPS Transactions:PartB (정보처리학회논문지B)

Korea Information Processing Society (한국정보처리학회)
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Combining Sentimental Expression-level and Sentence-level Classifiers to Improve Subjective Sentence Classification

감정 표현구 단위 분류기와 문장 단위 분류기의 결합을 통한 주관적 문장 분류의 성능 향상

  • Published : 2007.12.31
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Abstract

Subjective sentences express opinions, emotions, evaluations and other subjective ideas relevant to products or events. These expressions sometimes can be seen in only part of a sentence, thus extracting features from a full-sentence can degrade the performance of subjective-sentence-classification. This paper presents a method for improving the performance of a subjectivity classifier by combining two classifiers generated from the different representations of an input sentence. One representation is a sentimental phrase that represents an automatically identified subjective expression or objective expression and the other representation is a full-sentence. Each representation is used to extract modified n-grams that are composed of a word and its contextual words' polarity information. The best performance, 79.7% accuracy, 2.5% improvement, was obtained when the phrase-level classifier and the sentence-level classifier were merged.

주관적 문장이란 주관적인 내용을 포함한 문장으로써 저자의 제품이나 사건에 대한 생각을 알 수 있다. 주관적 내용임을 나타내는 주관적인 표현은 문장 전반적으로 골고루 나타날 수도 있지만 일부 한정된 영역에서만 발견될 수도 있다. 따라서 보다 정확한 분류를 위해서는, 문장 전체를 고려하는 정보 외에 사실이나 감정을 표현하는 주관적 혹은 객관적 표현구 정보의 활용이 필요하다. 본 연구에서는 문장 전체를 이용한 분류 결과와 감정 표현구를 이용한 분류 결과를 결합하여 주/객관적 문장 분류기의 성능을 향상시키는 방법을 제안한다. 한 문장은 여러 개의 표현구를 가질 수 있어 복수개의 표현구 단위 결과를 얻게 되며 기계 학습을 응용하여 문장 단위 결과와 결합한다. 실험을 통한 결과, 표현구 단위 결과물 중 최대값을 가지는 두 가지 결과와 문장 전체를 이용한 결과를 합침으로써 2.5% 성능 향상된 79.7%의 정확률을 얻을 수 있었다.

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