• KIISE Transactions on Computing Practices
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• v.21 no.4
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• pp.320-326
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• 2015

With the growing concern over frequent occurrences of criminal events, help-requesting mobile applications have drawn attention. However, existing applications solely focus on providing help-requesting services. Therefore, in this paper, we design and implement a help request and response process which allows users to request help by sending messages and locating their friends, acquaintances and even near-by application users, and to allow help be reached by forwarding messages. This application is composed of three parts: help-requesting, help-responding, and checking-status. This application is developed on the Android platform where we exchange users' longitude and latitude through web server communication. We conducted test to verify the effectiveness of the forwarding function, and it has been confirmed that 93.33% of subjects used the forwarding function to help users at risk.

• Proceedings of the Korea Information Processing Society Conference
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• 2017.11a
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• pp.144-146
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• 2017

사회적 약자로 여겨지는 여성과 아동을 대상으로 한 범죄들이 연신 화제가 되면서 이들의 안전을 위한 어플리케이션들의 출시가 늘고 있다. 2017년 현재 시중에 출시되어 있는 어플리케이션들은 '특정버튼 세 번 누르기', '해당 어플리케이션 실행시키기'와 같은 평범한 액션으로 사용자가 보호자에게 도움을 요청 할 수 있다. 하지만 본 프로젝트에서는 '낙하'라는 보다 더 간단한 액션으로 사용자가 빠른 도움 요청을 할 수 있는 시스템을 개발하였다. 블루투스 통신 모듈과 아두이노, 센서, 배터리를 사용하여 낙하를 감지할 수 있는 디바이스를 제작하였고 이와 통신할 수 있는 어플리케이션을 개발하여 디바이스의 낙하가 감지되면 문자 전송과 통화 연결기능을 수행할 수 있도록 하였다.

• Proceedings of the Korean Society of Computer Information Conference
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• 2018.07a
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• pp.221-222
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• 2018

본 논문에서는 android의 accelerometer sensor를 활용하여 예기치 못한 상황에 사용자를 보호 할 수 있는 어플리케이션을 설계하고 구현한다. 이 어플리케이션은 스마트폰을 흔들 때 accelerometer sensor가 센싱하여 어플리케이션을 자동으로 실행한다. 또한 경광등 소리를 울리고 사용자의 위치정보를 어플리케이션에 저장된 지인의 연락처로 전송한다. 사용자는 자신이 빈번하게 다니는 경로를 저장할 수 있으며, 이 경로에 대한 정보를 연락처에 저장된 지인들에게 제공한다. 이 어플리케이션을 사용하는 사용자는 범죄로부터 자신을 지키고, 위험한 경우 주변 사람들에게 도움을 요청할 수 있는 기능을 제공한다.

• Journal of KIISE:Software and Applications
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• v.32 no.12
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• pp.1164-1177
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• 2005

As the software development process becomes complicated, software requirements become complicated, too. Many efforts are needed in requirements management. It is impossible to define all requirements of software at first, and the development environment changes as project is gone. As the cost of requirements change management is much more than development cost, the changes should be controled immediately through systematic change management. In this paper, I suggest a method to manage requirements change systematically based on the change management process in software product lines. The requirements change at the application engineering process is analyzed and managed using the domain engineering process because the application requirements are customized from the domain requirements in software product lines. Such the consistent change management helps to make decisions about changes by change impact analysis and alternative solution design. Through this method, the potential change costs can be saved because same change requests are not repeated by controlling the change requests completely.

• The KIPS Transactions:PartC
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• v.10C no.5
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• pp.625-634
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• 2003

More than a decade after its initial proposal, deployment of IP Multicast has been limited due to the problem of traffic control in multicast routing, multicast address allocation in global internet, reliable multicast transport techniques etc. Lately, according to increase of multicast application service such as internet broadcast, real time security information service etc., overlay multicast is developed as a new internet multicast technology. In this paper, we describe an overlay multicast protocol and propose fast join mechanism that considers switching of the tree. To find a potential parent, an existing search algorithm descends the tree from the root by one level at a time, and it causes long joining latency. Also, it is try to select the nearest node as a potential parent. However, it can't select the nearest node by the degree limit of the node. As a result, the generated tree has low efficiency. To reduce long joining latency and improve the efficiency of the tree, we propose searching two levels of the tree at a time. This method forwards joining request message to own children node. So, at ordinary times, there is no overhead to keep the tree. But the joining request came, the increasing number of searching messages will reduce a long joining latency. Also searching more nodes will be helpful to construct more efficient trees. In order to evaluate the performance of our fast join mechanism, we measure the metrics such as the search latency and the number of searched node and the number of switching by the number of members and degree limit. The simulation results show that the performance of our mechanism is superior to that of the existing mechanism.