• KIPS Transactions on Software and Data Engineering
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• v.8 no.12
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• pp.507-516
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• 2019

Costs invested in road maintenance and road development are on the rise. However, due to accidents such as portholes and ground subsidence, the risks to the drivers' safety and the material damage caused by accidents are also increasing. Following this trend, we have developed a system that determines road damage, according to the magnitude of vibration generated without directly intervening the driver when driving. In this paper, we implemented the system using a remote control car (RC car) simulator due to the limitation of the environment in which the actual vehicle is not available in the process of developing the system. In addition, we attached a vibration sensor and GPS sensor to the body of the RC car simulator to measure the vibration value and location information generated by the movement of the vehicle in real-time while driving, and transmitting the corresponding data to the server. In this way, we implemented a system that allows external users to check the damage of roads and the maintenance of the repaired roads based on data more easily than the existing systems. By using this system, we can perform early prediction of road breakage and pattern prediction based on the data. Further, for the RC car simulator, commercialization will be possible by combining it with business in other fields that require flatness.

• Spatial Information Research
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• v.19 no.5
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• pp.63-74
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• 2011

Recently, there has been much interest in the spatial query which energy-efficiently acquires sensor readings from sensor nodes inside specified geographical area of interests. The centralized approach which performs the spatial query at a server after acquiring all sensor readings, though simple, it incurs high wireless transmission cost in accessing all sensor nodes. In order to remove the high wireless transmission cost, various in-network spatial indexing schemes have been proposed. They have focused on reducing the transmission cost by performing distributed spatial filtering on sensor nodes. However, these in-network spatial indexing schemes have a problem which cannot optimize both the spatial filtering and the wireless routing among sensor nodes, because these schemes have been developed by simply applying the existing spatial indexing schemes into the in-network environment. Therefore, we propose a new distributed spatial indexing scheme of the GR-tree. The GR-tree which form s a MBR-based tree structure, can reduce the wireless transmission cost by optimizing both the efficient spatial filtering and the wireless routing. Finally, we compare the existing spatial indexing scheme through extensive experiments and clarify our approach's distinguished features.

• Journal of the Korea Society of Computer and Information
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• v.18 no.7
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• pp.111-123
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• 2013

To verify software vulnerability, the method of conjecturing software structure and then testing the software based on the conjectured structure has been highlighted. To utilize the method, an efficient way to conjecture software structure is required. The popular graph and tree methods such as DFG(Data Flow Graph), CFG(Control Flow Graph) and CFA(Control Flow Automata) have a serious drawback. That is, they cannot express software in a hierarchical fashion. In this paper, we propose a method to overcome the drawback. The proposed method applies various input data to a binary code, generate CFG's based on the code output and construct a HCFG (Hierarchical Control Flow Graph) to express the generated CFG's in a hierarchical structure. The components required for HCFG and progressive algorithm to construct HCFG are also proposed. The proposed method is verified through constructing the software architecture of an open SMTP(Simple Mail Transfer Protocol) server program. The structure generated by the proposed method and the real program structure are compared and analyzed.

• Journal of the Korean Institute of Intelligent Systems
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• v.15 no.6
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• pp.714-719
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• 2005

The paper attempts to design and implement the system which can remotely check visitors' speech or Image by a mobile phone. This system is designed to recognize who a visitor is through the automatic calling service, not through a short message, via the mobile phone, even when the home owner is outside. In general, door locks are controlled through the home Server, but it is more effective to control door locks by using DTMF signal from a real-time point of view. The technology suggested in this paper makes it possible to communicate between the visiter and the home owner by making a phone call to tile home owner's mobile phone automatically when the visiter visits the house even if the home owner is outside, and if necessary, it allows for the home owner to control the door lock remotely. Thanks to the system, the home owner is not restricted by time or space for checking the visitor's identification and controlling the door lock. In addition, the security system is improved by changing from the existing password form to the combination of password and speaker verification lot the verification procedure required for controlling the door lock and setting the environment under consideration of any disadvantages which may occur when the mobile Phone is lost. Also, any existing problems such as reconnection to tile network for controlling tile door lock are solved by controlling the door lock in real time by use of DTMF signal while on the phone.

• International Commerce and Information Review
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• v.19 no.4
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• pp.29-50
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• 2017

In emerging technologies, innovation processes are dynamic in that the government needs to regularly review its policies to resonate with rapid technological advancements, changing public needs, and evolving global trends. In the 1990s, the Internet grew at an explosive rate, but many applications were constrained due to security concerns. Public Key Infrastructure (PKI) seemed to be the fundamental technology to address these concerns by providing security functions. As of 2017, PKI is still one of the best technologies for electronic authentication in an open network, but it is used only in limited areas: for user authentications in closed networks and for server authentications within network security infrastructure like SSL/TLS. The difference between expectation and reality of PKI usage is due to the evolution of the Internet along with the global adoption of new authentication policies under the Internet governance in the early 2000s. The new Internet governance based on the cooperation between multi-stakeholders is changing the way in which a government should act with regard to its technological policies. This paper analyzes different PKI policy approaches in the United States and Korea from the perspective of path-dependence theory. Their different policy results show evidence of the rise of the Internet governance, and may have important implications for policy-makers in the current global Internet society.

• Journal of The Korean Association of Information Education
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• v.17 no.3
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• pp.253-264
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• 2013

We development the service that teacher and parent can control the smart phone of student in school and home, the name is I_smart_keeper. The service is composed of server system, teacher's application, parent's application and student's application. The control of student's phone in school is operated by school timetable and GPS(Global Positioning System) in smart phone. The student's phone is operating one of six policy. The six policy is 'emergency call only', 'specific application only', 'call only', 'call and text only', 'all allowed' and 'all lock'. The teacher can change the current policy with his or her phone, That is a the temporary policy can be applied on a day. In school hours, teacher is able to instruct student using application appropriate to the teaching. If student is leaving school early and located outside school, the service do free the student's phone by GPS of her or his phone. We show the Smart Health Indicator (SHI)that analyse the pattern of student's phone habit and SHI will guide a desirable student's phone habit. In home, parent can control child's phone. The service will help the risk reduction of a robbery case due to keeping student's phone by teacher in class. Currently one elementary school's all student use I_smart_keeper and three elementary school is testing to some class. The teacher's impression was very good and they usually use I_smart_keeper for class in positive light. Survey results for students with higher satisfaction.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.1
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• pp.42-52
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• 2017

DASH (Dynamic Adaptive Streaming over HTTP) is an adaptive streaming technique that enables transmission of multimedia content when clients request the multimedia contents to server. In this system, to ensure the best quality of the content to satisfy users, it is necessary to precisely measure the residual bandwidth. However, the measured residual bandwidth by the DASH, which is not considering the transmission features of TCP, varies by the size of previous media segment, which makes it hard to ensure QoE to users. In this paper, we excluded the TCP Slow start range from measurement of residual bandwidth and suggested the new DASH bandwidth measuring method to decrease the error. Then, we realized the method in DASH system based on open source, and compared the existing measuring method. The new method showed that the accuracy of result has increased by 20%. Also, it could improve the QoE of users in terms of service quality and number of changes of segment quality.

• The KIPS Transactions:PartC
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• v.12C no.7 s.103
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• pp.1057-1066
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• 2005

WebDAV(Web-based Distributed Authoring and Versioning), a protocol which supports web-based distributed authoring and versioning, provides a standard infrastructure for asynchronous collaboration on various contents through the Internet. A WebDAV property management is a function to set and manage the main information of the resources as properties, and a user property, one kind of the WebDAV properties, has the ability to be freely defined by users. This free definition of user property makes it very useful to develop web-based applications like a collaboration system based on WebDAV However, with an existing WebDAV property management scheme, there is a limit to develop various applications. This paper describes a DavUP(WebDAV User property design Protocol) protocol which extended the original WebDAV and its uti-lization which efficiently supports management of WebDAV user properties. DavUP needs the definition of the collection structure and type definition properties for an application. To do this, we added a new header md appropriated WebDAV method functions to the WebDAV protocol. To show the usefulness of DavUP protocols, we extended our DAVinci WebDAV server to support DavUP Protocols and experimentally implemented a general Open Workspace, which provides effective functions to share and exchange open data among general users, on the DAVinci.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.2B
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• pp.279-288
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• 2004

Rapidly emerging P2P(Peer to Peer) applications generate very bursty traffic, which gives a lot of burden to network, and the amount of such traffic is increasing rapidly. Thus it is becoming more important to understand the characteristics of such traffic and reflect it when we design and analyze the network. To do that we measured the traffic in a campus network and present flow statistics and traffic models of the measured traffic, and compare them with those of the web traffic. The results indicate that P2P traffic is much burstier than web traffic and as a result it negatively affects network performance. We modeled P2P traffic using self-similar traffic model to predict packet delay and loss occurred in network which are very important to evaluate network performance. We also predict queue length distribution and loss probability in SSQ(Single Sewer Queue). To assess accuracy of traffic model, we compare the SSQ statistics of traffic models with that of the traffic trace. The results show that self-similar traffic models we use can predict P2P traffic behavior in network precisely. It is expected that the traffic models we derived can be used when we design network capacity and predict network performance and QoS of the P2P applications.

• Journal of the Korean Society of Radiology
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• v.1 no.2
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• pp.13-22
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• 2007

The purpose of this study was to survey a development of the wireless transmission system of medical images for ubiquitous medicine. There have been many changes in medical equipments and medical record medical treatment and medical record within hospital and PACS(Picture Archiving Communication System) which is picture management system for patients can be typical cases. It is difficult to use these automated medical systems unless they are within hospital and in case of rapid image reading in the emergency cases or in absence of doctor, it is difficult to perform it immediately. The present study implemented an image transmission system using CDMA connection so that images in the server can be viewed at any time and in any place. Remote wireless diagnosis based on medical images using PDA is applicable to medical areas that require mobility, and the use of PDA can be an ideal alternative for point of care. The use of PDA enables prompt and accurate access to digital medical images, which in turn reduces medical accidents and improves the quality of medical services through high productivity and efficiency of medical practitioners' works. It also enables quick response to patients' demands and high-quality medical services and, consequently, patients' high satisfaction.