• Journal of the Ergonomics Society of Korea
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• v.19 no.3
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• pp.51-60
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• 2000

Non-verbal sound feedback, called earcon, has been used for portable digital electronic products to give appropriate information for the selected function. This study evaluated usability based on user cognition time, error rate, and subjective satisfaction using 20 male and female subjects. The study compared five major user functions from a portable digital electronic product with currently available earcons and the same functions from the product with the new earcons (suggested by this study) which considered user cognitive characteristics, such as loudness, pitch, melody, and length. For subjective evaluation, the study assessed various earcons by subjective impression of sounds using the seven-point rating scales. Major statistical results indicated that the new earcons significantly reduced user error rates and generally improved user performance functions, such as 'play, off, stop, fast forward, and rewind.'

• Journal of Drive and Control
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• v.18 no.4
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• pp.77-83
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• 2021

With the progress in virtual reality technology, various virtual objects can be displayed using head-mounted displays (HMD). However, force feedback sensations such as pushing against a virtual object are not possible with an HMD only. Focusing on force feedback, desktop-type devices are generally used, but the user cannot move in a virtual space because such devices are fixed on a desk. With a wearable force feedback device, users can move around while experiencing force feedback. Therefore, the authors have developed a wearable force feedback device using a magnetorheological fluid clutch and pneumatic rubber artificial muscle, aiming at presenting the elasticity, friction, and viscosity of an object. To date, we have developed a wearable four-degree-of-freedom (4-DOF) force feedback device and have quantitatively evaluated that it can present commanded elastic, frictional, and viscous forces to the end effector. However, sensory evaluation with a human has not been performed. In this paper, therefore, we conduct a sensory evaluation of the proposed method. In the experiment, frictional and viscous forces are rendered in a virtual space using a 4-DOF force feedback device. Subjects are asked to answer questions on a 1- to 7-point scale, from 1 (not at all) to 4 (neither) to 7 (strongly). The Wilcoxon signed rank test was used for all data, and answer 4 (neither) was used as compared standard data. The experimental results confirmed that the user could feel the presence or absence of viscous and frictional forces. However, the magnitude of those forces was not sensed correctly.

• Journal of Korea Multimedia Society
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• v.21 no.2
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• pp.242-249
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• 2018

In this paper, the customized sports convergence contents curation system is proposed for activation of life sports. The proposed system collects and analyzes profile of social sports group (club, society, etc.) for recommending optimized sports convergence contents to user. In addition, the feedback based on the recommendation result from the user is continuously reflected and the optimal recommendation is made possible. For the system evaluation, the proposed system is tested to 300 users (about 20 sports team) for about 3 months and the system is verified by analyzing the initial recommendation results and recommendation results reflected by user feedback.

• Journal of the Korea Society of Computer and Information
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• v.3 no.1
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• pp.35-46
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• 1998

In the Information Retrieval System. the relevance of retrieved items is determined by the judgement of the user and thus the evaluation of the system efficiency counts on the cognizance of users to some extent. The relevance feedback mechanism provides a device allowing iterative searches during which the query can be modified and refined based on user input from the relevant documents. The feedback system are generally reported to outperform non-feedback systems. The procedures and algorithms to implement the feedback mechanism are surveyed in this paper.

• Journal of Software Engineering Society
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• v.27 no.1
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• pp.8-14
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• 2018

As cloud computing has emerged as a hot trend in the IT industry, various types of cloud services have emerged. In addition, cloud service broker (CSB) technology has emerged to alleviate the complexity of the process of selecting the desired service that user wants among the various cloud services. One of the key features of the CSB is to recommend the best cloud services to users. In general, CSB can use a method to evaluate a service by receiving feedback about a service from users in order to recommend a cloud service. However, since each user has different criteria for giving a rating, there is a problem that reliability of service evaluation can be low when the rating is only used. In this paper, a method is proposed to supplement evaluation of rating based service by applying machine learning based sentiment analysis to cloud service user's review. In addition, the CSB prototype is implemented based on proposed method. Further, the results of comparing the performance of various learning algorithms is proposed that can be used for sentiment analysis through experiments using actual cloud service review as learning data. The proposed service evaluation method complements the disadvantages of the existing rating-based service evaluation and can reflect the service quality in terms of user experience.

• Journal of Engineering Education Research
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• v.17 no.2
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• pp.35-41
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• 2014

This paper deals with the ways that can improve the reliability of the course evaluation system based on reformation of the system and design of user interface for the practical applications. In the reformation of the system aspect, there are the improvements of the course evaluation questionnaires and the feedback of course evaluation to the lecturers. In the design aspect, a computer screen of the graphic user interface is redesigned to reflect the reformation of the system aspect issues. The results show the effectiveness in the reliability improvement.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39A no.1
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• pp.65-67
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• 2014

In this letter, the performance of the interference channel with continuously varying channel is evaluated by using interference alignment based on practical channel estimation and channel state information(CSI) feedback and ideal Doppler frequency estimation. In this paper, performance evaluation is performed in terms of sum rate for 3-user interference channel. And also, sum rate is measured according to frequency of channel estimation relating with the calculation complexity. Simulation results show that the proposed scheme outperforms the conventional one which assumes that the channel is constant in a frame in some circumstances.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.12 no.2
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• pp.181-186
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• 2012

This paper proposes a method for evaluating web pages by considering implicit user reaction on web pages. Usually users spend more time and make more reactions, such as clicking, dragging and scrolling, while reading interesting pages. Based on this observation, a web page evaluation method by observing implicit user reaction is proposed. The system is designed with Ajax for observing user reactions, and neural networks for learning correlation between user reactions and usefulness of pages. The amounts of each type of user reactions are inputted to neural networks. Also the numbers of characters and images of pages are used as inputs because the amount of users' behaviors has a tendency to increase as the length of pages increase. The experiment is conducted with 113 people and 74 pages. Each page is ranked by users with a questionnaire. The proposed method shows more close ranking results to the user ranks than Google. That is, our system evaluates web pages more closely to users' viewpoint than Google. Although our experiment is limited, our result shows powerful potential of new element for web page evaluation. Some approaches evaluate web pages with their contents and some evaluate web pages with structural attributes, particularly links, of pages. Web page evaluation is for users, so the best evaluation can be done by users themselves. So, user feedback is one of the most important factors for web page evaluation. This paper proposes a new method which reflects user feedbacks on web pages.

• International Journal of Contents
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• v.5 no.1
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• pp.51-55
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• 2009

In this paper, we present a structure of personalized e-Learning system to study for a test formalized by uniform multiple-choice using on/off line mixed estimations as is the case of Driver :s License Test in Korea. Using the system a candidate can study toward the license through the Internet (and/or mobile instruments) within the personalized concept based on IRT(item response theory). The system accurately estimates user's ability parameter and dynamically offers optimal evaluation problems and learning contents according to the estimated ability so that the user can take possession of the license in shorter time. In order to establish the personalized e-Learning concepts, we build up 3 databases and 2 agents in this system. Content DB maintains learning contents for studying toward the license as the shape of objects separated by concept-unit. Item-bank DB manages items with their parameters such as difficulties, discriminations, and guessing factors, which are firmly related to the learning contents in Content DB through the concept of object parameters. User profile DB maintains users' status information, item responses, and ability parameters. With these DB formations, Interface agent processes user ID, password, status information, and various queries generated by learners. In addition, it hooks up user's item response with Selection & Feedback agent. On the other hand, Selection & Feedback agent offers problems and content objects according to the corresponding user's ability parameter, and re-estimates the ability parameter to activate dynamic personalized learning situation and so forth.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.5B
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• pp.489-497
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• 2009

In the 3GPP LTE and IEEE 802.16m standardizations for IMT-Advanced, the efficient transmission of multicast and broadcast data is one of the important issues to improve system performance. Especially, to guarantee each user's QoS in the multicast group, H-ARQ or adaptive modulation are considered to be adoption, however, reduction of feedback overhead is one of the most important issues. In this paper, performance of the previously proposed OOK (On-Off Keying) based common ACK/NACK feedback channel is analyzed through theoretical analysis and simulation. Based on the results, system parameter optimization methods for common feedback channel are proposed. In addition, through computer simulation, it is shown that the common feedback method according to the proposed feedback parameter optimization can feedback ACK/NACK information for multicast H-ARQ transmission, more reliably than the conventional user dedicated feedback method in 3GPP LTE systems, and can reduce the feedback overhead as well.