• Journal of KIISE:Software and Applications
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• v.29 no.9
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• pp.669-675
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• 2002

In recent years most of personalized recommender systems in electronic commerce utilize collaborative filtering algorithm in order to recommend more appropriate items. User-based collaborative filtering is based on the ratings of other users who have similar preferences to a user in order to predict the rating of an item that the user hasn't seen yet. This nay decrease the accuracy of prediction because the similarity between two users is computed with respect to the two users and only when an item has been rated by the users. In item-based collaborative filtering, the preference of an item is predicted based on the similarity between the item and each of other items that have rated by users. This method, however, uses the ratings of users who are not the neighbors of a user for computing the similarity between a pair of items. Hence item-based collaborative filtering may degrade the accuracy of a recommender system. In this paper, we present a new approach that a user's neighborhood is used when we compute the similarity between the items in traditional item-based collaborative filtering in order to compensate the weak points of the current item-based collaborative filtering and to improve the prediction accuracy. We empirically evaluate the accuracy of our approach to compare with several different collaborative filtering approaches using the EachMovie collaborative filtering data set. The experimental results show that our approach provides better quality in prediction and recommendation list than other collaborative filtering approaches.

• Journal of KIISE:Computing Practices and Letters
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• v.8 no.6
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• pp.669-678
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• 2002

Currently, the domestic interests on the development of eyesight related measuring instruments are being increased. So we are developing such an electronic system of Refracto-keratometer, which contains a software and a hardware both. If this system could inform the examiner of the precise eyesight measuring result from the treatment of the image of optical system, then potentially the number of missed measuring results could be reduced. Our electronic system has been developed from the two areas divided into a software and a hardware. The software area was focused on the more exact eyesight measuring results, using morphological filtering methods and gray-leveled signal enhancing techniques. The hardware area is performing the same functions as the existing other systems. Besides, it provides the embedded software with free variables which could reduce the developing duration sharply as well as enlarge many kinds of application-extensions. Therefore, this electronic system has made effective eyesight measurement possible as the result of reducing the differences applied to sophisticated eyesight measurement.

• Proceedings of the Korean Information Science Society Conference
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• 2002.10d
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• pp.286-288
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• 2002

엄청난 속도로 증가하고 있는 정보의 홍수 시대에서는 정보들을 선별하기 위하여 정보 필터링 기법이 필요하다. 정보 필터링은 내용 기반 방법과 협력에 의한 방법으로 분류할 수 있다. 내용 기반 기법에서는 내용에 기반을 두어 정보를 추출하는 반면 협력 기법은 대상이 되는 사용자에 대한 예측을 하기 위하여 다른 사람들의 의견들을 이용하게 된다. 본 논문에서는 기존 협력 필터링 방법의 문제점을 해결하기 위한 방법의 일환으로 내용 기반 기법과 협력 기법을 보다 유기적으로 결합시키는 연구를 수행하였다. 이를 위해 협력 필터링 틀을 그대로 유지하면서 사용자 프로파일을 효과적으로 이용하는 방법을 제안하였다. 또한, 본 논문에서 제시한 기법을 실험적으로 분석하고 기존의 필터링 기법과 비교함으로써 제시된 기법의 우수성을 보였다.

• Proceedings of the Korea Information Processing Society Conference
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• 2017.11a
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• pp.450-453
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• 2017

현대사회가 발전함으로 인해 사람들의 질이 높아졌고 보다 행복한 삶을 찾는 사람들이 많아졌다. 그로인해 공연 문화의 시장은 커졌고 공연의 종류와 수가 매우 많아졌다. 이에 따라 사용자에게 만족되는 조건과 가격의 공연을 추천하기란 어려운 일이다. 따라서 본 논문에서는 개인화 요인과 협업 필터링 방법을 이용하여 사용자에게 보다 적합한 공연을 추천하며 협업필터링의 큰 단점 중 하나인 희소성 문제에 대해 보다 나은 추천 시스템을 제안한다.

• Proceedings of the Korea Information Processing Society Conference
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• 2019.10a
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• pp.44-47
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• 2019

스마트 폰과 태블릿 PC를 이용하여 실시간 영상 재생 서비스(OTT: Over The Top)를 이용하는 사람들이 폭발적으로 증가하고 있다. 그에 따라 실시간 영상 재생 서비스를 즐길 수 있는 수많은 콘텐츠들이 증가하고 있다. 이에 따라 사용자는 자신의 취향에 맞는 드라마가 어떤 드라마인지 찾기가 어렵다. 따라서 본 논문에서는 사용자 스타일에 가장 적합한 미국 드라마 추천 시스템을 제안하기 위하여 선호 장르 2개, 연령대, 성별, 미국인 여부를 이용하여 유클리드 방법으로 유사도를 계산하고 협업 필터링 방법을 적용하여 드라마를 추천하는 시스템을 R을 이용하여 구현하였다.

• Proceedings of the Korea Information Processing Society Conference
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• 2013.05a
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• pp.1100-1102
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• 2013

현대사회에서는 외모가 내 외적으로 자신을 나타내는 지표이자 상징이며, 사회적 위치나 경제적 상황, 자아정체성을 대변할 수 있다. 또한 경제능력이 향상되고 기존의 성역할 개념의 약화, 사회진출과 인간관계 유지를 위해 남성들도 외모관리에 대한 관심이 높아지기 시작했다. 본 논문은 비교적 화장품에 대한 정보를 잘 알지 못하는 남성들을 대상으로 웹에서 사용자의 나이, 피부톤, 피부타입에 알맞은 화장품을 추천해주는 시스템을 소개한다.

• Journal of KIISE:Software and Applications
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• v.29 no.4
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• pp.270-277
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• 2002

Text filtering is a task of deciding whether a document has relevance to a specified topic. As Internet and Web becomes wide-spread and the number of documents delivered by e-mail explosively grows the importance of text filtering increases as well. The aim of this paper is to improve the accuracy of text filtering systems by using machine learning techniques. We apply AdaBoost algorithms to the filtering task. An AdaBoost algorithm generates and combines a series of simple hypotheses. Each of the hypotheses decides the relevance of a document to a topic on the basis of whether or not the document includes a certain word. We begin with an existing AdaBoost algorithm which uses weak hypotheses with their output of 1 or -1. Then we extend the algorithm to use weak hypotheses with real-valued outputs which was proposed recently to improve error reduction rates and final filtering performance. Next, we attempt to achieve further improvement in the AdaBoost's performance by first setting weights randomly according to the continuous Poisson distribution, executing AdaBoost, repeating these steps several times, and then combining all the hypotheses learned. This has the effect of mitigating the ovefitting problem which may occur when learning from a small number of data. Experiments have been performed on the real document collections used in TREC-8, a well-established text retrieval contest. This dataset includes Financial Times articles from 1992 to 1994. The experimental results show that AdaBoost with real-valued hypotheses outperforms AdaBoost with binary-valued hypotheses, and that AdaBoost iterated with random weights further improves filtering accuracy. Comparison results of all the participants of the TREC-8 filtering task are also provided.

• Proceedings of the Korea Information Processing Society Conference
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• 2019.05a
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• pp.267-269
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• 2019

There are many recommendation systems offer an effort to get better preciseness the information to the users. In order to further improve more accuracy, the social network analysis method which is used to analyze data to community detection in social networks was introduced in the recommendation system and the result shows this method is improving more accuracy. In this paper, we propose a movie recommendation system using social network analysis and normalized discounted cumulative gain with the best accuracy. To estimate the performance, the collaborative filtering using the k nearest neighbor method, the social network analysis with collaborative filtering method and the proposed method are used to evaluate the MovieLens data. The performance outputs show that the proposed method get better the accuracy of the movie recommendation system than any other methods used in this experiment.

• Journal of IKEEE
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• v.23 no.4
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• pp.1393-1399
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• 2019

With the rapid growth of the Internet, millions of indiscriminate advertising SMS are sent every day because of the convenience of sending and receiving data. Although we still use methods to block spam words manually, we have been actively researching how to filter spam in a various ways as machine learning emerged. However, spam words and patterns are constantly changing to avoid being filtered, so existing machine learning mechanisms cannot detect or adapt to new words and patterns. Recently, the concept of Lifelong Learning emerged to overcome these limitations, using existing knowledge to keep learning new knowledge continuously. In this paper, we propose a method of spam filtering system using ensemble techniques of naive bayesian which is most commonly used in document classification and LLML(Lifelong Machine Learning). We validate the performance of lifelong learning by applying the model ELLA and the Naive Bayes most commonly used in existing spam filters.

• Journal of Internet Computing and Services
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• v.21 no.1
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• pp.79-85
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• 2020

Today, to block spam texts on smartphone, a simple string comparison between text messages and spam keywords or a blocking spam phone numbers is used. As results, spam text is sent in a gradually hanged way to prevent if from being automatically blocked. In particular, for words included in spam keywords, spam texts are sent to abnormal words using special characters, Chinese characters, and whitespace to prevent them from being detected by simple string match. There is a limit that traditional spam filtering methods can't block these spam texts well. Therefore, new technologies are needed to respond to changing spam text messages. In this paper, we propose a knowledge graph-based new words detection mechanism that can detect new words frequently used in spam texts and respond to changing spam texts. Also, we show experimental results of the performance when detected Korean new words are applied to the Naive Bayes algorithm.