• Proceedings of the Korea Information Processing Society Conference
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• 2016.10a
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• pp.587-590
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• 2016

최근 통신 기술의 발달로 온라인을 통한 대규모 콘텐츠의 유통이 가능해졌으나, 사용자들은 수많은 콘텐츠 사이에서 원하는 정보를 찾는 시간이 단축되는 것을 원했다. 이로 인해 다양한 분야에서 개인화된 콘텐츠를 추천해주는 추천 시스템(recommendation system)에 대한 요구가 점차 높아졌다. 그럼에도 불구하고 시니어를 위한 추천 시스템에 대한 연구는 매우 부족하다. 또한, 시니어 세대의 변화에 따라 시니어 관련 콘텐츠 연구도 다양하게 진행되고 있으나, 스마트 기기 및 서비스가 젊은 층에 친화적으로 개발됨으로써 시니어 층의 접근성을 감소시키고 있다. 이에 본 연구에서는 다양한 신체적 변화를 겪는 시니어 세대 위해 추천 시스템에서 인지반응 데이터를 이용하여 콘텐츠를 시청하기 적합한 환경을 제공함과 동시에 활동 이력을 중심으로 개인화 추천 시스템을 설계하여 시니어 사용자들의 개념 변화(concept drift) 문제로 사용자가 원하지 않는 콘텐츠를 추천받을 가능성을 줄일 수 있도록 한다.

• Journal of the Korea Society of Computer and Information
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• v.27 no.7
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• pp.93-100
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• 2022

In the era of information overload on the Internet, the recommendation system, which is an indispensable function, is a service that recommends products that a user may prefer, and has been successfully provided in various commercial sites. Recently, studies to reflect the rating time of items to improve the performance of collaborative filtering, a representative recommendation technique, are active. The core idea of these studies is to generate the recommendation list by giving an exponentially lower weight to the items rated in the past. However, this has a disadvantage in that a time function is uniformly applied to all items without considering changes in users' preferences according to the characteristics of the items. In this study, we propose a time-aware collaborative filtering technique from a completely different point of view by developing a new similarity measure that integrates the change in similarity values between items over time into a weighted sum. As a result of the experiment, the prediction performance and recommendation performance of the proposed method were significantly superior to the existing representative time aware methods and traditional methods.

• Journal of the Korea Society of Computer and Information
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• v.27 no.1
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• pp.83-89
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• 2022

As a representative technique of recommender systems, collaborative filtering has been successfully in service through many commercial and academic systems. This technique recommends items highly rated by similar neighbor users, based on similarity of ratings on common items rated by two users. Recently research on time-aware recommender systems has been conducted, which attempts to improve system performance by reflecting user rating time of items. However, the decay rate uniform to past ratings has a risk of lowering the rating prediction performance of the system. This study proposes a rating time-aware similarity measure between users, which is a novel approach different from previous ones. The proposed approach considers changes of similarity value over time, not item rating time. In order to evaluate performance of the proposed method, experiments using various parameter values and types of time change functions are conducted, resulting in improving prediction accuracy of existing traditional similarity measures significantly.

• Proceedings of the Korea Information Processing Society Conference
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• 2012.11a
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• pp.1681-1684
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• 2012

병원에 진료를 받기 위해 찾아온 환자들은 병원의 복잡한 시스템과 구조 때문에 어려움을 겪는다. 이러한 문제점을 해결하기 위하여 모바일 컴퓨팅을 이용한 다양한 진료 안내 시스템이 제안되었지만, 환자의 상황, 위치 등을 인지하기 위하여 별도의 장치를 사용하기 때문에 초기 구축비용이 많이 들고, 환자의 스케줄을 의료진이 수동으로 설정해야 하는 단점이 있다. 본 논문에서는 이러한 단점을 해결하기 위하여 환자의 진료가 끝난 즉시 의사, 간호사 등의 의료진이 다음 진료를 설정한 후 환자의 스마트폰으로 진료 정보를 제공하는 상황인지 기반 진료안내 시스템을 제안한다. 또한, 환자가 받아야 할 진료의 대기시간을 비교하여 대기시간이 짧은 진료를 추천해주는 진료 순서 추천 시스템을 제안한다. 본 논문에서 제안한 진료 순서 추천 시스템과 기존 방법과의 성능 평가를 통하여 기존 방법보다 제안한 방법이 우수함을 보인다.

• Journal of the Korea Society of Computer and Information
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• v.27 no.9
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• pp.149-155
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• 2022

The popularity of e-commerce systems on the Internet is increasing day by day, and the recommendation system, as a core function of these systems, greatly reduces the effort to search for desired products by recommending products that customers may prefer. The collaborative filtering technique is a recommendation algorithm that has been successfully implemented in many commercial systems, but despite its popularity and usefulness in academia, the memory-based implementation has inaccuracies in its reference neighbor. To solve this problem, this study proposes a new time-aware collaborative filtering technique that integrates and utilizes the neighbors of each item and each user, weighting the recent similarity more than the past similarity with them, and reflecting it in the recommendation list decision. Through the experimental evaluation, it was confirmed that the proposed method showed superior performance in terms of prediction accuracy than other existing methods.

• Journal of the Korea Society of Computer and Information
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• v.28 no.10
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• pp.163-170
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• 2023

The user-based collaborative filtering technique, one of the implementation methods of the recommendation system, recommends the preferred items of neighboring users based on the calculations of neighboring users with similar rating histories. However, it fundamentally has a data scarcity problem in which the quality of recommendations is significantly reduced when there is little common rating history. To solve this problem, many existing studies have proposed various methods of combining Jaccard index with a similarity measure. In this study, we introduce a time-aware concept to Jaccard index and propose a method of weighting common items with different weights depending on the rating time. As a result of conducting experiments using various performance metrics and time intervals, it is confirmed that the proposed method showed the best performance compared to the original Jaccard index at most metrics, and that the optimal time interval differs depending on the type of performance metric.

• Journal of the Korea Society of Computer and Information
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• v.28 no.5
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• pp.75-82
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• 2023

In collaborative filtering systems, the item rating prediction values calculated by the systems are very important for customer satisfaction with the recommendation list. In the time-aware system, predictions are calculated by reflecting the rating time of users, and in general, exponentially lower weights are assigned to past rating values. In this study, to find out whether the influence of rating time on the rating value varies according to various factors, the correlation between user rating value and rating time is investigated by the degree of user rating activity, the popularity of items, and item genres. As a result, using two types of public datasets, especially in the sparse dataset, significantly different correlation index values were obtained for each factor. Therefore, it is confirmed that the influence weight of the rating time on the rating prediction value should be set differently in consideration of the above-mentioned various factors as well as the density of the dataset.

• Proceedings of the Korean Society of Computer Information Conference
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• 2023.07a
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• pp.55-58
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• 2023

본 논문에서는 스마트 미러 사용자의 얼굴 인식, 표정 인식, 얼굴형 인식을 활용하여 감정에 적절한 멘트와 화장법을 제공하는 시스템의 개발 내용에 관해 기술한다. 이 시스템을 사용함으로써 사람들은 자신의 감정을 정확하게 인지할 뿐만 아니라 위로와 공감을 받을 수 있으며, 자신의 스타일에 적절한 화장법을 추천받을 수 있다. 스마트 미러를 통해, 사용자는 자기 이해도가 늘어나게 되어 스스로에게 더욱 집중할 수 있고 화장법을 찾는 시간이나 화장에 실패할 가능성이 줄어들어 시간과 비용을 절약할 수 있게 될 것이다.

• The Journal of Korean Institute of Next Generation Computing
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• v.13 no.2
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• pp.35-48
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• 2017

There are many and various devices like sensors, displays, smart phone, etc. in smart environment. And contents can be provided by using these devices. Vast amounts of contents are provided to users, but in most environments, there are no regard for user or some simple elements like location and time are regarded. So there's a limit to provide meaningful contents to users. In this paper, I suggest the contents recommendation system that can recommend contents to users by reasoning context of users, devices and contents. The contents recommendation system suggested in this paper recommend the contents by calculating the user preferences using the situation reasoned with the contextual data acquired from various devices and the user profile received from the user directly. To organize this process, the method on how to model ontology with domain knowledge and how to design and develop the contents recommendation system are discussed in this paper. And an application of the contents recommendation system in Centum City, Busan is introduced. Then, the evaluation methods how the contents recommendation system is evaluated are explained. The evaluation result shows that the mean absolute error is 0.8730, which shows the excellent performance of the proposed contents recommendation system.

• Journal of Internet Computing and Services
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• v.8 no.5
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• pp.81-89
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• 2007

In this thesis, we propose ontology based context-aware recommendation system using concept hierarchy(OCARCH), Context-aware recommendation services are useful to provide an user with relevant information and/or services bared on his current context, However several approaches to context-aware recommendation system have been already proposed, each of them provide information without considering level of information concept bared on his current context, For this reason, we propose OCARCH as system capable of helping people to find their way quickly and easily through large amounts of information by determining level of information concept based on his current context, We are also using prefetching algorithm to store recommendation information that the user is likely to need in the near future based on current predictions, Therefore the OCARCH enables users to obtain relevant information efficiently, Several experiments are performed and the experimental results show that the proposed system provides more effective than conventional context-aware recommendation system.