# Korean Historical Documents Analysis with Improved Dynamic Word Embedding
###### Abstract  
Historical documents refer to records or books that provide textual information about the thoughts and consciousness of past civilisations, and therefore, they have historical significance. These documents are used as key sources for historical studies as they provide information over several historical periods. Many studies have analysed various historical documents using deep learning; however, studies that employ changes in information over time are lacking. In this study, we propose a deep-learning approach using improved dynamic word embedding to determine the characteristics of 27 kings mentioned in the Annals of the Joseon Dynasty, which contains a record of 500 years. The characteristics of words for each king were quantitated based on dynamic word embedding; further, this information was applied to named entity recognition and neural machine translation.In experiments, we confirmed that the method we proposed showed better performance than other methods. In the named entity recognition task, the F1-score was 0.68; in the neural machine translation task, the BLEU4 score was 0.34. We demonstrated that this approach can be used to extract information about diplomatic relationships with neighbouring countries and the economic conditions of the Joseon Dynasty. Keywords:historical documents; deep-learning; dynamic word embedding; named entity recognition; neural machine translation; transformer +
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periods of time. Research has been performed to understand various languages which have embedded words, such as Portuguese [7] or Lithuanian [8], but the studies are limited in their analysis of the passage of time. Several researchers are focused on studying the changes over time [9,10], however, they are concentrating only on decades, so the work is not suitable for understanding and analysing the changes in word meanings over a long period of time. Therefore, we aim to capture semantic changes over time in historical documents. We utilise a representative Korean historical record, i.e., the Annals of the Joseon Dynasty (AJD). The AJD--a UNESCO World Record Heritage ([[http://www.unesco.org/new/en/communication-and-information/memory-of-the-world/register/full-list-of-registered-heritage/registered-heritage-page-8/the-annals-of-the-choson-dynasty/](http://www.unesco.org/new/en/communication-and-information/memory-of-the-world/register/full-list-of-registered-heritage/registered-heritage-page-8/the-annals-of-the-choson-dynasty/)]([http://www.unesco.org/new/en/communication-and-information/memory-of-the-world/register/full-list-of-registered-heritage/registered-heritage-page-8/the-annals-of-the-choson-dynasty/](http://www.unesco.org/new/en/communication-and-information/memory-of-the-world/register/full-list-of-registered-heritage/registered-heritage-page-8/the-annals-of-the-choson-dynasty/)))--is an extensive historical document that contains a considerable amount of information related to politics, economy, culture, society, and weather during the Joseon Dynasty, and it has information that spans over 500 years, ruled by 27 kings. Th AJD comprises 50 million characters in the 1893 volumes of the 888 books; it is a detailed and comprehensive historical document. The original text has now been digitised; in addition, a version translated by experts is available. The AJD has been used in research in the fields of politics, culture, metrology, and medicine [11, 12, 13, 14, 15, 16, 17]. However, these analyses were performed over the entire period of 500 years, thereby making it difficult to differentiate between the specific characteristics or ideologies of each king. The AJD covers the longest continual period of a single dynasty compared to other historical documents. We used improved dynamic word embedding (DWE) to capture the semantic changes in the historical document. The semantic changes were quantified based on the embedding vector obtained from DWE.