• Journal of the Korea Society of Computer and Information
• /
• v.16 no.2
• /
• pp.83-91
• /
• 2011

Much research has been conducted on the e-learning systems for recommending a learning content to a student based on the difficulty of it. The difficulty is one of the most important factors for selecting a learning content. In the existing learning content recommendation systems, the difficulty of a learning content is determined by the creator. Therefore, it is not easy to apply a standard rule to the difficulty as it is determined by a subjective method. In this paper, we propose an ontology-based method for determining the difficulty of a learning content in order to provide an objective measurement. Previously, ontologies and knowledge maps have been used to recommend a learning content. However, their methods have the same problem because the difficulty is also determined by the creator. In this research, we use an ontology representing the IS-A relationships between words. The difficulty of a learning content is the sum of the weighted path lengths of the words in the learning content. By using this kind of difficulty, we can provide an objective measurement and recommend the proper learning content most suitable for the student's current level.

• Journal of KIISE:Computing Practices and Letters
• /
• v.9 no.5
• /
• pp.521-529
• /
• 2003

In this paper we present an improved method by using demographic information for overcoming the similarity miss-calculation from the sparsity problem in collaborative filtering recommendation systems. The similarity between a pair of users is only determined by the ratings given to co-rated items, so items that have not been rated by both users are ignored. To solve this problem, we add virtual neighbor's rating using demographic information of neighbors for improving prediction accuracy. It is one kind of extentions of traditional collaborative filtering methods using the peason correlation coefficient. We used the Grouplens movie rating data in experiment and we have compared the proposed method with the collaborative filtering methods by the mean absolute error and receive operating characteristic values. The results show that the proposed method is more efficient than the collaborative filtering methods using the pearson correlation coefficient about 9% in MAE and 13% in sensitivity of ROC.

• Journal of KIISE:Software and Applications
• /
• v.37 no.3
• /
• pp.185-193
• /
• 2010

With the emergence of ubiquitous computing era, various models for providing personalized service have been proposed, and, especially, several recommendation service schemes have been proposed to give tailored services to users proactively. However, the previous recommendation service schemes utilize a wide range of data without and filtering and consider the limited context-aware information to predict user preferences so that they are not adequate to provide personalized service to users. In this paper, we propose an adaptive recommendation service scheme which proactively provides suitable services based on the current context. We use accumulated interaction contexts (IC) between users and devices for predicting the user's preferences and recommend adaptive service based on the current context by utilizing clustering and collaborative filtering. The clustering algorithm improves efficiency of the recommendation service by focusing and analyzing the data that is collected from the locations nearby the users. Collaborative filtering guarantees an accurate recommendation, even when the data is insufficient. Finally, we evaluate the performance and the reliability of the proposed scheme by simulations.

• The Journal of Society for e-Business Studies
• /
• v.16 no.3
• /
• pp.191-209
• /
• 2011

In a buyer-seller transaction process, 'value for money,' a measure of quality-price-ratio, is one of the most important criteria for buyers' purchasing decisions. The purpose of this paper is to suggest a method which helps online shoppers choose the best of several sellers offering homogeneous goods. We suggest FDH (free disposal hull) model, an applied model of data envelopment analysis (DEA), for online buyer-seller transactions and verify it with the data from an Internet comparison shopping site. For this purpose, we analyze consumer choice behaviors by examining how consumers respond to different sale conditions such as price, brand, or delivery time. Then, we implement a seller recommendation system to support buyers' purchasing decisions. We expect our FDH model to provide valuable information for rational buyers who want to pay the least price for high quality products/services and to be used in implementing automated evaluation processes in micro transactions. Moreover, we expect that our results can be utilized for sellers' benchmarking strategies which help sellers be more competitive by showing them how to attract buyers.

• Journal of the Korea Society of Computer and Information
• /
• v.20 no.2
• /
• pp.11-20
• /
• 2015

In this paper, we propose a context awareness system to transfer accurate information of the app store based on collective intelligence. By using collective intelligence the system minimizes the errors that could occur when an individual process the problems, recommends APIs for developers and builds the app store for not only customers but also developers. In addition, this system applies the ontology technique to aware the context of consumers, recommends the app suitable for the consumer and provides the information for app developers. By utilizing the deduction technique of the Jena, the context awareness system infers the context of a consumer and constructs the app store system which improves the existing app stores. In the point of service transfer and accuracy, the proposed app store system module show better performance than the existing app store.

• The Journal of Korean Association of Computer Education
• /
• v.11 no.1
• /
• pp.11-21
• /
• 2008

In advance of Knowledge Information Society, mentoring is becoming an efficient method for developing and managing human resources. There are several factors to improve the effect of mentoring. Among them, a matching mechanism that connects a mentee and a mentor is the most important in mentoring. In the existing e-mentoring systems, administrators rarely consider personal data. They match suitable mentors for mentees in a mandatory way, which reflects bad effects in the e-mentoring. In this paper, we propose new recommendation algorithms for matching by analyzing personal preferences for secondary school students to improve the effects of the mentoring. In addition, we compare our algorithms with the existing algorithms in terms of elaborateness, accordance, and diversity in order to prove the effectiveness of the proposed algorithms.

• Journal of Korea Multimedia Society
• /
• v.12 no.5
• /
• pp.688-698
• /
• 2009

The market for Internet fashion/coordination shopping malls has been enormously increased year by year. However, online shoppers feel inconvenient because most of Internet shopping malls still rely on item classifications by category and do not provide the functionality in terms of which shoppers can find clothes they want. In an effort to build a fashion/coordination system for women's dress adopting the Heuristic-based method, one of the Context-based methods, we present a method for defining characteristics of a woman's dress as attributes and their inheritance relations, which can be input by a product manager. We also compare and analyze various methods for recommending the most similar clothes.

• Journal of Intelligence and Information Systems
• /
• v.6 no.1
• /
• pp.17-34
• /
• 2000

본 논문에서는 분신과 지능형 쇼핑에이전트에 입각한 새로운 개념의 가상현실 인터넷 쇼핑몰을 제안한다. 특히 본 논문에서 제안하는 인터넷 쇼핑몰은 기존의 쇼핑몰과는 달리 전체적인 설계를 웹에 기초한 의사결정지원시스템 즉 웹 DSS 개념에 기초하고 있다 일반적으로 전통적인 DSS의 경우 모델 데이터 그리고 사용자 인터페이스를 기본 구성요소로하고 있는데 본 논문에서 제안하는 인터넷 쇼핑몰은 모델로서는 지능형 쇼핑에이전트를 데이터로서는 각종 제품 정보 및 상용자 기호를 사용자 인터페이서로서는 분신(Avatar) 및 웹 환경을 전제로 한다. 특히 본 논문에서 제안하는 인터넷 쇼핑몰의 모든 의사결정지원과정은 웹 DSS 개념에 기초한다. 또한 소비자들의 흥미성과 몰입감 증대를 위하여 전체적인 환경을 가상현실로 하였다 본 논문에서 제안하는 인터넷 쇼핑몰인 VRISA의 특징을 요약하면 우선 라이프스타일 에이전트와 선호속성 에이전트를 가지고 있어서 이를 기초로 하여 소비자의 라이프스타일 확인 및 선호속성을 파악할 수가 있으며 또한 해당 라이프스타일 및 선호속성에 맞는 제품을 추천할 수도 있다 이같은 에이전트의 작동결과는 분신으로 반영되어 해당 분신이 적절한 제품을 소비자에게 추천할 수 있으며 모든 제품추천환경 및 분신의 작동환경은 가상현실 환경으로 구축되어 있어서 소비자들의 흥미성과 몰입감을 증대시킬 수가 있다. 이는 소비자들의 구매의도 향상에 크게 기여할 수가 있다.

• Journal of the Korea Society of Computer and Information
• /
• v.26 no.5
• /
• pp.47-53
• /
• 2021

Sparse ratings data hinder reliable similarity computation between users, which degrades the performance of memory-based collaborative filtering techniques for recommender systems. Many works in the literature have been developed for solving this data sparsity problem, where the most simple and representative ones are the methods of utilizing Jaccard index. This index reflects the number of commonly rated items between two users and is mostly integrated into traditional similarity measures to compute similarity more accurately between the users. However, such integration is very straightforward with no consideration of the degree of data sparsity. This study suggests a novel idea of applying different similarity measures depending on the numeric value of Jaccard index between two users. Performance experiments are conducted to obtain optimal values of the parameters used by the proposed method and evaluate it in comparison with other relevant methods. As a result, the proposed demonstrates the best and comparable performance in prediction and recommendation accuracies.

• Journal of Intelligence and Information Systems
• /
• v.18 no.2
• /
• pp.177-192
• /
• 2012

This is a study of match-making systems that considers the mutual satisfaction of matching partners. Recently, recommendation systems have been applied to people recommendation, such as recommending new friends, employees, or dating partners. One of the prominent domain areas is match-making systems that recommend suitable dating partners to customers. A match-making system, however, is different from a product recommender system. First, a match-making system needs to satisfy the recommended partners as well as the customer, whereas a product recommender system only needs to satisfy the customer. Second, match-making systems need to include as many participants in a matching pool as possible for their recommendation results, even with unpopular customers. In other words, recommendations should not be focused only on a limited number of popular people; unpopular people should also be listed on someone else's matching results. In product recommender systems, it is acceptable to recommend the same popular items to many customers, since these items can easily be additionally supplied. However, in match-making systems, there are only a few popular people, and they may become overburdened with too many recommendations. Also, a successful match could cause a customer to drop out of the matching pool. Thus, match-making systems should provide recommendation services equally to all customers without favoring popular customers. The suggested match-making system, called Mutually Beneficial Matching (MBM), considers the reciprocal satisfaction of both the customer and the matched partner and also considers the number of customers who are excluded in the matching. A brief outline of the MBM method is as follows: First, it collects a customer's profile information, his/her preferable dating partner's profile information and the weights that he/she considers important when selecting dating partners. Then, it calculates the preference score of a customer to certain potential dating partners on the basis of the difference between them. The preference score of a certain partner to a customer is also calculated in this way. After that, the mutual preference score is produced by the two preference values calculated in the previous step using the proposed formula in this study. The proposed formula reflects the symmetry of preferences as well as their quantities. Finally, the MBM method recommends the top N partners having high mutual preference scores to a customer. The prototype of the suggested MBM system is implemented by JAVA and applied to an artificial dataset that is based on real survey results from major match-making companies in Korea. The results of the MBM method are compared with those of the other two conventional methods: Preference-Based Matching (PBM), which only considers a customer's preferences, and Arithmetic Mean-Based Matching (AMM), which considers the preferences of both the customer and the partner (although it does not reflect their symmetry in the matching results). We perform the comparisons in terms of criteria such as average preference of the matching partners, average symmetry, and the number of people who are excluded from the matching results by changing the number of recommendations to 5, 10, 15, 20, and 25. The results show that in many cases, the suggested MBM method produces average preferences and symmetries that are significantly higher than those of the PBM and AMM methods. Moreover, in every case, MBM produces a smaller pool of excluded people than those of the PBM method.