• Journal of the Korean Society for Library and Information Science
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• v.26
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• pp.167-185
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• 1994

The purpose of this study is to develop the optimal user/librarian interface in information searching. In order to achive the purpose, the 150 unskilled students as subjects have participated in the study. According to the change of the subjects' psychological information states by the access points within the library system, the subjects have been classified into the five types of model: the initial information state, the accepted identification information state, the bibliographic information state, the stack information state, and the location information state. Librarian's searching support is done for 10 minutes at the each access points. To develop the optimal user/librarian interface, the expected values of the models are calculated. The resultants are as follows: 1) The expected value of the initial information states model is 18.94: 2) The expected value of the accepted identification information model is 27.06: 3) The expected value of the bibliographic information state model is 27.06: 4) The expected value of the stack information state model is 22.38: 5) The expected value of the location information state model is 22.38. Those expected values are compared with each other. The model with the lowest expected value is chosen as the optimal user/librarian interface model. In the result, the user's initial information state model of the optimal user/librarian interface in information searching is developed. In order to search the information with the most effect, user must be interfaced with the librarian at his/her own initial information state.

• IE interfaces
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• v.16 no.spc
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• pp.21-27
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• 2003

Objective of this paper is to develop the user mobility model(UMM) which is used for the performance analysis of location update and paging algorithm and at the same time, consider the user mobility pattern(UMP) in zone-based cellular networks. User mobility pattern shows correlation in space and time. UMM should consider these correlations of UMP. K-dimensional Markov chain is presented as a UMM considering them where the states of Markov chain are defined as the current location area(LA) and the consecutive LAs visited in the path. Also, a new two dimensional Markov chain composed of current LA and time interval is presented. Simulation results show that the appropriate size of K in the former UMM is two and the latter UMM reflects the characteristic of UMP well and so is a good model for the analytic method to solve the performance of location update and paging algorithm.

• Journal of Industrial Technology
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• v.28 no.B
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• pp.27-32
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• 2008

In this paper, we implement the taxi telematics service system based on location based service(LBS). The system implementation is composed of 3 major parts : the mobile device with which a user requests taxi calls, the taxi client which resides inside a taxi and supports multimedia environments with navigation function, and the server which manages moving taxies and receives user taxi calls. From the mobile device's GPS information, the server finds the closest taxi which is then sent to the user with the mobile device.

• Journal of the Korea Society of Computer and Information
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• v.27 no.12
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• pp.161-169
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• 2022

With the development of mobile devices and global positioning systems, various location-based services can be utilized, which collects user's location information and provides services based on it. In this process, there is a risk of personal sensitive information being exposed to the outside, and thus Geo-indistinguishability (Geo-Ind), which protect location privacy of LBS users by perturbing their true location, is widely used. However, owing to the data perturbation mechanism of Geo-Ind, it is hard to accurately obtain the density distribution of LBS users from the collection of perturbed location data. Thus, in this paper, we aim to develop a novel method which enables to effectively compute the user density distribution from perturbed location dataset collected under Geo-Ind. In particular, the proposed method leverages Expectation-Maximization(EM) algorithm to precisely estimate the density disribution of LBS users from perturbed location dataset. Experimental results on real world datasets show that our proposed method achieves significantly better performance than a baseline approach.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.27 no.2
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• pp.201-212
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• 2017

As services using mobile devices increase, exposure of personal information, and secure threats increase. In this paper, we propose a location-based user authentication system used in mobile device for tightening security. Our authentication system is performed to authenticate two steps. The first authentication is location authentication to ensure that the user accesses an application in trustable space. This authentication method uses an Access Point's information. The second authentication is trustable space authentication to confirm the normal user. This method is carried out the authentication by using biometric information from the user.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.27 no.5
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• pp.1069-1076
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• 2017

Recently $Pok\acute{e}mon$ GO implements an online game with location-based real time augmented reality on mobile. The correct play of this game should be based on collecting the $Pok\acute{e}mon$ that appears as the user moves around by foot, but as the popularity increases, it appears an abuse to play easily. Many people have used an application that provides a mock location service such as Fake GPS, and these applications can be judged to be cheating in online games because they can play games in the house without moving. Detection of such cheating from a client point of view (mobile device) can consume a large amount of resources, which can reduce the speed of the game. It is difficult for developers to apply detection methods that negatively affect game usage and user's satisfaction. Therefore, in this paper, we propose a method to detect users abusing mock location service in online game by route analysis using GPS location record from the server point of view.

• Journal of Korea Society of Industrial Information Systems
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• v.18 no.3
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• pp.27-34
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• 2013

As smart phone is daily used by most people, various location-based applications have been developed. Moreover, it is increased the requirements of location-based services that utilize Google maps, GPS sensing information and etc.. In this paper, we develop a smart phone application providing notification services by detecting the daily route deviation. We develop the server system which receives GPS information gathering from user's smart phone and analyse the user's regular routes. With the results from the analyzation the GPS coordinates, the application on a smart phone detects the case of a breakaway from regular routes. And then it can inform automatically and immediately the designed person such as guardians of children or the old and the infirm of the route deviation so will be helpful to protect such person. This is one example of the effectiveness of the application. Moreover, the application is developed on the client-server framework, thus it is very useful to judge the user's daily route deviation in realtime by using the accumulated information on the corresponding DB. Finally we evaluated the proposed methods which had been implemented on smart phones and show the utilities of the application.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.27 no.5
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• pp.1033-1047
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• 2017

Traditional explicit authentication, which requires awareness of the user's authentication process, is a burden on the user, which is one of main reasons why users tend not to employ authentication. In this paper, we try to reduce such cost by employing implicit authentication methods, such as biometrics and location based authentication methods. We define the 4-level security assurance model, where each level is mapped to an explicit authentication method. We implement our model as an Android application, where the implicit authentication methods are touch-stroke dynamics-based, face recognition based, and the location based authentication. From user experiment, we could show that the authentication cost is reduced by 14.9% compared to password authentication-only case and by 21.7% compared to the case where 6-digit PIN authentication is solely used.

• Proceedings of the Korea Information Processing Society Conference
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• 2014.04a
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• pp.294-297
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• 2014

스마트폰에 내장된 배터리 절전 모드는 불특정 다수에게 배터리 소모를 줄이기 위한 동일한 작업을 수행한다. 하지만 사용자들은 제각기 다른 방식으로 스마트폰을 사용하기 때문에 위와 같은 절전모드는 배터리 향상에 크게 도움을 주지 않는다. 본 연구는 사용자의 행동 반경을 통하여 개개인의 패턴에 따라 스마트폰의 배터리를 절약하는데 도움을 주는 "BatteryDiet" 어플리케이션을 통해 기존 배터리 소모에 비해 약 27%정도 더 배터리를 사용할 수 있었다.

• Journal of The Korea Institute of Healthcare Architecture
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• v.24 no.4
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• pp.27-35
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• 2018

Purpose: The diverse users and the increase of power wheelchair users have made it difficult to apply the standards of Wheelchair user accessible toilet rooms for the existing law and BF-certification. To address these issues, the standards of the relevant laws have been improved (Ministry of Health and Welfare, 2018), but there are still many problems. In this study, problems with the standards for Wheelchair user accessible toilet rooms in Korea are analyzed by comparing national and international standards. In addition, improvements to standards for Wheelchair user accessible toilet rooms will be suggested. Method: It presents improvement for standards of Wheelchair user accessible toilet rooms by comparing national, international standard and standards of many countries. Korean standard, International Standard(ISO 21542), American Standard(ADA Standards), German Standard(DIN 18040-1), Austrian Standard($\ddot{O}NORM$ B 1600) and Swiss Standard(Norm SIA 500) were investigated and analyzed. Results: Korea's standards differ from the ISO and the Standards of other countries in many ways, so there is a need for realignment. Specifications for disabled toilets and clear criteria for the size, shape, and location of sanitary appliances in toilets that are practically available to wheelchair users should be provided. Considering the increasing number of disabled toilet users, the installation of various disabled toilet rooms should be considered considering the user characteristics of those who can walk and wheelchair users. Implication: Recent partial improvements to relevant laws cannot meet the requirements of various users. Therefore, comprehensive and clear standard should be presented that take into account changing society and the environment.