• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.4
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• pp.510-516
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• 2019

In this paper, a snowboard simulator that measures the user's motion and makes the user feel physical changes and enjoy actual snowboarding was developed. The speed and direction of the snowboard are determined by the user's center of gravity. The developed simulator is equipped with four springs on the snowboard plate, so that the slope can change according to the change in the user's weight center and be felt directly. The slope due to the change in the center of gravity of the user is measured using a three-axis acceleration sensor. The friction of the slope generated by the rotation of the snowboard is made possible by the user using the BLDC motor, and the rotation of the snowboard is measured using the hole sensor. For rapid data processing of the simulator, two MCUs are used to transfer the measured data to the PC using the acceleration sensor and motor separately. The developed simulator can experience slopes and friction of the slope directly, and wear measured data and HMD to enjoy more realistic snowboarding.

• Journal of Advanced Information Technology and Convergence
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• v.8 no.2
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• pp.79-87
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• 2018

The current PC user authentication uses character password based on user's knowledge. However, this can easily be exploited by password cracking or key-logging programs. In addition, the use of a difficult password and the periodic change of the password make it easy for the user to mistake exposing the password around the PC because it is difficult for the user to remember the password. In order to overcome this, we propose user gesture recognition and challenge-response authentication. We apply user's hand gesture instead of character password. In the challenge-response method, authentication is performed in the form of responding to a quiz, rather than using the same password every time. To apply the hand gesture to challenge-response authentication, the gesture is recognized and symbolized to be used in the quiz response. So we show that this method can be applied to PC user authentication.

• Journal of Korea Society of Digital Industry and Information Management
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• v.8 no.4
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• pp.99-105
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• 2012

Recently, there are many user selection algorithms in multi user multiple-input multiple-output (MU-MIMO) systems. One of well-known user selection methods is Semi orthogonal user selection (SUS). It is an algorithm maximizing channel capacity. However, it is applicable only when user's antenna is one. We propose a generalized user selection algorithm regardless of the number of user's antennas. In the proposed scheme, Base station (Bs) selects the first user who has the highest determinant of channel and generates a user group that correlation with first user's channel is less than allowance of correlation. Then, each determinant of channels made up of first user's channel and a user's channel in the generated group is calculated and BS selects the next user who has the highest determinant of that. BS selects following users by repeating above procedure. In this paper, we get better performance because of selecting users who have the highest determinant of channel as well as allowance of correlation optimally calculated through matrix operations.

• Proceeding of Spring/Autumn Annual Conference of KHA
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• 2005.11a
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• pp.63-66
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• 2005

The purpose of this study is to suggest the modeling of ubiquitous environments according to the analysis of user's behaviors focused on the living area within the house. Recently, with appearing 'Ubiquitous environments', the applications of ubiquitous technologies on the our environment adopt a new paradigm. This new paradigm leads to the possibility of creating more intellectual dwelling environment according to user's behaviors. This paper suggests to change our dwelling by considering both engineering technology and the character of dwelling, because the house should provide causes humans with comfortability. Therefore, we need to understand user's behaviors in the dwelling, towards user friendly environment. Also, it very important for us to configure proper sensors and technologies by the priority based on user's behaviors. To sum up, this study is aimed to analyze user's behaviors and then, to suggest the guideline for users offering optimal ubiquitous environments.

• Journal of Intelligence and Information Systems
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• v.17 no.2
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• pp.39-60
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• 2011

Since the introduction of web 2.0 technology, social network service has been recognized as the foundation of an important future information technology. The advent of web 2.0 has led to the change of content creators. In the existing web, content creators are service providers, whereas they have changed into service users in the recent web. Users share experiences with other users improving contents quality, thereby it has increased the importance of social network. As a result, diverse forms of social network service have been emerged from relations and experiences of users. Social network is a network to construct and express social relations among people who share interests and activities. Today's social network service has not merely confined itself to showing user interactions, but it has also developed into a level in which content generation and evaluation are interacting with each other. As the volume of contents generated from social network service and the number of connections between users have drastically increased, the social network extraction method becomes more complicated. Consequently the following problems for the social network extraction arise. First problem lies in insufficiency of representational power of object in the social network. Second problem is incapability of expressional power in the diverse connections among users. Third problem is the difficulty of creating dynamic change in the social network due to change in user interests. And lastly, lack of method capable of integrating and processing data efficiently in the heterogeneous distributed computing environment. The first and last problems can be solved by using FOAF, a tool for describing ontology-based user profiles for construction of social network. However, solving second and third problems require a novel technology to reflect dynamic change of user interests and relations. In this paper, we propose a novel method to overcome the above problems of existing social network extraction method by applying FOAF (a tool for describing user profiles) and RSS (a literary web work publishing mechanism) to OLAP system in order to dynamically innovate and manage FOAF. We employed data interoperability which is an important characteristic of FOAF in this paper. Next we used RSS to reflect such changes as time flow and user interests. RSS, a tool for literary web work, provides standard vocabulary for distribution at web sites and contents in the form of RDF/XML. In this paper, we collect personal information and relations of users by utilizing FOAF. We also collect user contents by utilizing RSS. Finally, collected data is inserted into the database by star schema. The system we proposed in this paper generates OLAP cube using data in the database. 'Dynamic FOAF Management Algorithm' processes generated OLAP cube. Dynamic FOAF Management Algorithm consists of two functions: one is find_id_interest() and the other is find_relation (). Find_id_interest() is used to extract user interests during the input period, and find-relation() extracts users matching user interests. Finally, the proposed system reconstructs FOAF by reflecting extracted relationships and interests of users. For the justification of the suggested idea, we showed the implemented result together with its analysis. We used C# language and MS-SQL database, and input FOAF and RSS as data collected from livejournal.com. The implemented result shows that foaf : interest of users has reached an average of 19 percent increase for four weeks. In proportion to the increased foaf : interest change, the number of foaf : knows of users has grown an average of 9 percent for four weeks. As we use FOAF and RSS as basic data which have a wide support in web 2.0 and social network service, we have a definite advantage in utilizing user data distributed in the diverse web sites and services regardless of language and types of computer. By using suggested method in this paper, we can provide better services coping with the rapid change of user interests with the automatic application of FOAF.

• Tribology and Lubricants
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• v.30 no.3
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• pp.168-176
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• 2014

This paper presents an engine oil change warning algorithm based on the test results of a small dip-stick-gage-type engine-oil-deterioration-detection sensor, software to realize the algorithm and a display device to apply the software. The algorithm determines the engine oil deterioration condition from the rate of change in the dielectric constant based on the average measured capacitance at $80^{\circ}C$ after the engine stops. The rate of change in the dielectric constant at the time for oil change correlates with the time that one of recommended warning limits for engine oil physical properties such as TAN (Total Acid Number), TBN (Total Base Number) and viscosity is first reached. At this point, a warning signal for oil change appears on the display device like a smart-phone or individual display device. The frames of smartphone app have three stages. The user can directly input all of the thresholds into the frame of the smartphone app. The screen of the display device comprises one frame for each warning signature with the related message. The user can input the thresholds to the device through a USB cable connected to a personal computer.

• Journal of the Ergonomics Society of Korea
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• v.31 no.2
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• pp.299-308
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• 2012

Objective: This study presents the conceptual framework and the conceptual model to account for user experience by expanding the existing concepts of usability, in particular considering the user-interface environment in digital convergence. Background: To better understand a variety of users interacting with a converged product based on digital technologies, there seems to be a limit to consider the existing concepts of usability. All possible aspects of user's interaction with a product in a context of use need to be taken into consideration. Method: This study identifies the concept of user experience through a comprehensive literature review. Results: First, this study reviews the existing concepts of usability and user experience. And then this study describes four main components in the conceptual framework of user experience: user's internal states, user's external states, a product, and various outcomes, each of which encompasses distinct sub-components. The conceptual model of user experience accounts for how user's internal states change over time and for how different sub-components affect actual behavior of use. Conclusion: It is expected that these user experience concepts can be used in basic resources to better understand different behavioral characteristics of users and to better design interactive products in converged digital environments.

• Proceedings of the Korean Institute of Interior Design Conference
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• 2006.05a
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• pp.202-205
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• 2006

Space design is a process of solving spatial problems to create and construct all kinds of human lives. It also bestows new values to a medium to induce human perception based on the relationships between 'human and space' surrounding people. Research on user behavior has several ultimate goals including understanding both individual behavior and the relations between the user and space from a more scientific and systematic perspective, predicting various phenomena that can happen between space and humans, and reflecting the results in space design. As user behavior that's once limited within given space is going through some changes due to the introduction of digital technologies, research on user behavior in today's space design should be newly illuminated in the aspects of organic relations. Space now works as a receptor communicating with the user and responding to user behavior, and user behavior once under one-sided influences from space becomes more diverse and active. The influences of user behavior, in turn, cause changes to space itself. Thus this study set out to suggest new directions in research on user behavior based on interactions between space and the user in space design.

• The Journal of Information Technology and Database
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• v.6 no.2
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• pp.1-18
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• 1999

The purpose of this study was to identify the effect of microcomputer networking on user perception of potential threats to security employing user attitudes as a moderating variable. A research model consisting of microcomputer networking as the independent variable, user perception of potential threats to security as the dependent variable, and user attitude toward security control as the moderating variable was developed through literature review. The results of this study provide an empirical evidence of the importance of environmental change(information systems networking) on user perception of potential threats to security. Further-more the result imply that in order to improve security performance through the reinforcement of user perception of threats to security in the organization, user attitudes should be made favorable.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.12 no.4
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• pp.270-276
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• 2012

With the increase in amount of data and information available on the web, there have been high demands on personalized information retrieval services to provide context-aware services for the web users. This paper proposes a novel dynamic multi-agent context-awareness user profile construction method based on ontology to incorporate concepts and properties to model the user profile. This method comprehensively considers the frequency and the specific of the concept in one document and its corresponding domain ontology to construct the user profile, based on which, a fuzzy c-means clustering method is adopted to cluster the user's interest domain, and a dynamic update policy is adopted to continuously consider the change of the users' interest. The simulation result shows that along with the gradual perfection of the our user profile, our proposed system is better than traditional semantic based retrieval system in terms of the Recall Ratio and Precision Ratio.