• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.05a
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• pp.933-936
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• 2008

Mobile devices such as cellular phones and PDA become a part of our life by extreme improvement of Wireless internet and arriving the age of Ubiquitous. Especially it makes increasing rapidly the expectations about a field of remote control that is great advantage of Mobile devices. Existing computer remote control systems are hard to meet user's appropriate manage when error happened because Clients could not recognize the state of several remote controlled computers which connected to web server. This paper Implementation remote computer control system that immediately after errors happen by send error massages in the from of a SMS to client by set the clients with cellular phone that most generally used Mobile devices.

• Journal of KIISE:Computing Practices and Letters
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• v.14 no.6
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• pp.589-593
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• 2008

These days, as a side effect of the growth of the mobile devices, malwares for the mobile devices also tend to increase and become more dangerous. Because embedded Linux is one of the advanced OSes on mobile devices, a solution to preventing malwares from infecting and destroying embedded Linux will be needed. We present a scheme using signature verification for embedded Linux that prevents executallle-Infecting malwares. The proposed scheme works under collaboration between mobile devices and a server. Malware detection is delegated to the server. In a mobile device, only integrity of all executables and dynamic libraries is checked at kernel level every time by kernel modules using LSM hooks just prior to loading of executables and dynamic libraries. All procedures in the mobile devices are performed only at kernel level. In experiments with a mobile embedded device, we confirmed that the scheme is able to prevent all executable-Infecting malwares while minimizing damage caused by execution of malwares or infected files, power consumption and performance overheads caused by malware check routines.

• Journal of KIISE:Computing Practices and Letters
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• v.15 no.1
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• pp.14-20
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• 2009

Recently, NAND flash memory is used not only for portable devices, but also for personal computers and server computers. Buffer cache replacement policies for the hard disks such as LRU and LFU are not good for NAND flash memories because they do not consider about the characteristics of NAND flash memory. CFLRU and its variants, CFLRU/C, CFLRU/E and DL-CFLRU/E(CFLRUs) are the buffer cache replacement policies considered about the characteristics of NAND flash memories, but their performances are not better than those of LRD. In this paper, we propose a new buffer cache replacement policy for NAND flash memory. Which is based on LFU and is taking into account the characteristics of NAND flash memory. And we estimate the performance of hit ratio and flush operation numbers. The proposed policy shows better hit ratio and the number of flush operation than any other policies.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.23 no.6
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• pp.1131-1141
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• 2013

Most of the single server model of cloud computing services have problems that are hard to solve, such as a service availability, insider attack, and vendor lock-in, etc. To solve these problems, the research about multicloud has emerged. Multicloud model can supplement previous cloud model's weakness and provides new services to user. In this paper, we focus on a user authentication problem in multicloud model and propose a scheme to resolve it. We define a cloud broker-based multicloud model. And we propose an authentication protocol that is applicable at presented model. The proposed scheme can provide service transparency to user and prevent an impersonation attack by service provider.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.18 no.6
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• pp.176-190
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• 2019

The prevention of pedestrian accidents in crosswalks and intersections is very important. The C-ITS services provide a warning service for preventing accidents between cars and pedestrians. In the current pedestrian collision prevention warning service according to the C-ITS standard, however, it is difficult to provide real-time service because it detects pedestrians from a video-analysis server in the control center and sends service messages through the ITS system. This paper proposes a pedestrian collision-prevention warning system that detects pedestrians in the local field using an edge camera and sends a warning message directly to the driver through a roadside unit. An evaluation showed that the proposed system could deliver the pedestrian collision prevention-warning message to the driver satisfying the delay time within the 300 ms required by the C-ITS standard, even in the worst case.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.38 no.4
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• pp.59-71
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• 2001

The Current CORBA shows some limitations for its successful deployment in real time system applications. Recently, OMG adopted Real-Time CORBA specification, which is defined as an extension to CORBA. The goal of the Real-Time CORBA is to provide a standard for CORBA ORB implementations that support 'end to end predictability'. In order to support 'end-to-end predictability', Real Time CORBA specifies many components such as priority model, communication protocol configuration, thread management, and etc. Among them, 'priority model' is the most important mechanism for avoiding or bounding priority inversion in CORBA invocations. In this paper, we present our efforts on a design ,and implementation of the Priority Model in Real-Time CORBA specification. The implementation is done as an extension of omniORB2(v.3.0.0), a popular open source non real time ORB. Experiment results demonstrate that our priority model implementation shows better performance and predictability than the non real-time ORB.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.23 no.5
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• pp.803-813
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• 2013

As the developments of smart devices and social network services, the amount of data has been exploding. The world is facing Big data era. For these reasons, the Big data processing technology which is a new technology that can handle such data has attracted much attention. One of the most representative technologies is Hadoop. Hadoop Distributed File System(HDFS) designed to run on commercial Linux server is an open source framework and can store many terabytes of data. The initial version of Hadoop did not consider security because it only focused on efficient Big data processing. As the number of users rapidly increases, a lot of sensitive data including personal information were stored on HDFS. So Hadoop announced a new version that introduces Kerberos and token system in 2009. However, this system is vulnerable to the replay attack, impersonation attack and other attacks. In this paper, we analyze these vulnerabilities of HDFS security and propose a new protocol which complements these vulnerabilities and maintains the performance of Hadoop.

• The KIPS Transactions:PartD
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• v.9D no.6
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• pp.1071-1082
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• 2002

Recent development in wireless computing and GPS technology cause the active development in the application system of location information in real-time environment such as transportation vehicle management, air traffic control and location based system. Especially, study about vehicle location tracking system, which monitors the vehicle's position in a control center, is appeared to be a representative application system. However, the current vehicle location tracking system can not provide vehicle position information that is not stored in a database at a specific time to users. We designed a vehicle location tracking system that could track vehicle location using mobile interface such as PDA. The proposed system consist of a vehicle location retrieving server and a mobile interface. It is provide not only the moving vehicle's current location but also the position at a past and future time which is not stored in database for users.

• Journal of KIISE:Databases
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• v.30 no.2
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• pp.184-196
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• 2003

Mobile transactions updating spatial objects are long transactions that can update independently local objects of mobile clients during disconnection. Validation based protocols that are well known to be appropriate for mobile transactions are required to abort a conflicted transaction in order to keep data consistent. Since abortion leads to cancel of all of tile updates, it is not desirable to use the abortion for resolving conflicts of mobile transactions. In this paper, we propose a reprocessing transaction model to resolve the update conflicts between mobile transactions without aborting them. We also design a mobile transaction server to support the reprocessing transaction and build a prototype of a mobile field system. The reprocessing transaction is a subtransaction of a newly committed mobile transaction and re-executes only conflicted objects with foreign conflicted objects. We also introduce a progressive reprocessing scheme to expose non-conflicted objects of the mobile transaction to other transactions in order to reduce starvation of reprocessing transactions.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.18 no.4
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• pp.183-189
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• 2018

With the recent advancement of vehicle wireless communication technology, many vehicular clouds have been proposed. The existing research focused on cloud services through data collection based on vehicular networks of mobile V2V (Vehicle-to-Vehicle) and V2I (Vehicle-to-Infrastructure). In this paper, we present a vehicular datacenter model that utilizes the vehicle in the parking space as a resource for the datacenter. Also, we derive resource allocation strategy based on the expected execution time considering the leave rate of each vehicle in our vehicular datacenter model. Simulation results show that our proposed resource allocation strategies outperform the existing strategy in terms of mean execution time.