• Journal of Platform Technology
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• v.9 no.4
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• pp.42-50
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• 2021

Recently, the need to introduce smart farms is increasing in order to solve the problems of intensifying competition such as a decrease in rural population due to aging, a decrease in production, and the inflow of foreign agricultural products, and accordingly, the need for education is increasing. This paper is a study on the implementation of an Android-based IoT smart farm for education so that it can be used in a real environment by reducing the farm's smart farm system. To confirm that Android-based education can be applied in a real environment using the IoT smart farm for education, experiments were performed in automatic mode and manual mode using Bluetooth, Wi-Fi, and server/client communication methods. In the automatic mode, the current status can be checked in real time by receiving all data, and in the manual mode, commands are transmitted in real time using the received sensor data and remote control is performed. As a result of the experiment, it was possible to understand the characteristics of each communication method, and it was confirmed that remote monitoring and remote control of the smart farm using the Android App was possible.

• Journal of KIISE:Computing Practices and Letters
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• v.13 no.5
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• pp.293-299
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• 2007

Intelligent pipeline inspection gauges (PIGs) are inspection vehicles that move along within a (gas or oil) pipeline and acquire signals (also called sensor data) from their surrounding rings of sensors. By analyzing the signals captured in intelligent PIGs, we can detect pipeline defects, such as holes and curvatures and other potential causes of gas explosions. There are two major data access patterns apparent when an analyzer accesses the pipeline signal data. The first is a sequential pattern where an analyst reads the sensor data one time only in a sequential fashion. The second is the repetitive pattern where an analyzer repeatedly reads the signal data within a fixed range; this is the dominant pattern in analyzing the signal data. The existing PIG software reads signal data directly from the server at every user#s request, requiring network transfer and disk access cost. It works well only for the sequential pattern, but not for the more dominant repetitive pattern. This problem becomes very serious in a client/server environment where several analysts analyze the signal data concurrently. To tackle this problem, we devise a fast in-memory cache manager, called T-Cache, by considering pipeline sensor data as multiple time-series data and by efficiently caching the time-series data at T-Cache. To the best of the authors# knowledge, this is the first research on caching pipeline signals on the client-side. We propose a new concept of the signal cache line as a caching unit, which is a set of time-series signal data for a fixed distance. We also provide the various data structures including smart cursors and algorithms used in T-Cache. Experimental results show that T-Cache performs much better for the repetitive pattern in terms of disk I/Os and the elapsed time. Even with the sequential pattern, T-Cache shows almost the same performance as a system that does not use any caching, indicating the caching overhead in T-Cache is negligible.

• Journal of Korea Spatial Information System Society
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• v.2 no.2 s.4
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• pp.25-37
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• 2000

As computer systems of high capacity and high performance recently emerged, various researches about GISs(Geographic Information Systems) have been in progress and many GIS applications have also been developed. From the domestic situation where many people are using mobile devices, because of the recent advances in the mobile technology, we can infer that the time will come when every individual will carry a mobile device with a GPS(Global Positioning System) module resulting from the development of a miniature GPS Module. Therefore, a mobile GIS that can allows users to deal with dynamic GIS data management and perform their tasks while moving will be required. This paper discusses the design and implementation of a mobile GIS using the shareware DBMS, called postgresSQL. The Mobile GIS in which a mobile concept is utilized at the GIS data server makes it possible to insert, delete, update GIS data, to zoom in and zoom out displayed maps, and to locate the user's position on the client device. Therefore, It is possible to manage dynamic GIS data in order to deal with GIS data on the maps while moving, connect various GIS data servers through the middleware, and connected with ITS (Intelligent Transport System) which is one of applications of the Mobile GIS developed in this paper.

• The Journal of the Korea Contents Association
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• v.14 no.1
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• pp.537-547
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• 2014

In this paper, the ALT (ALTernative) board and a NetLogo extension module are developed for the active participatory simulation (APS) learning. Through the participatory simulation with HubNet each student can attend the experiment as one of clients. Only one HubNet server, however, is able to use an external device so that the bifocal modeling based learning with multiple users is impossible. In order to overcome the drawback, and enable clients participate into the experiment and collect the experimental data and the measured data, an ATmega 32 based board and its firmware are developed. In addition, Java extension module based on TCP/IP socket interfaces is developed to exchange the data with HubNet server. Finally, we show some NetLogo program examples to use the developed hardware and software for APS and seek the way to use them for science education.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.8B
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• pp.535-540
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• 2005

This paper presents a scalable caching algorithm of proxy server with the finite storage size minimizing client's buffer size and constant-bit-rate channel bandwidth. Under the general video traffic condition, it is observed that the amount of decreased client's buffer size and channel bandwidth after caching a video frame depends on the relative frame position in the time axis as the frame size. Based on this fact, we propose an effective caching algorithm to select the cached frames by using the normalized buffer size. Finally, experimental results are provided to show the superior performance of the proposed alghrithm.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.42 no.3
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• pp.595-603
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• 2017

We propose a scheme to reduce the time for the SSL/TLS handshake by embedding it into the TCP 3-way handshake. The scheme can be selectively applied on the standard TCP for making the SSL/TCP handshake happen within the TCP handshake, rather than performing the TCP handshake and SSL/TLS handshake in sequence. We implemented a prototype of the scheme and did some experiments on its performance. Experimental results showed that, compared to the sequential handshakes of the TCP and the SSL/TLS, the time reduction achieved by the scheme varied in the range of 3.2% and 14%(when the elapsed time by the ping program from the client to the server was 11.6ms). The longer the time measured by the ping program, which would grow as the propagation and queuing delays do, the larger the reduction rate. It accords with the supposition that the reduced time due to the scheme will increase in proportion to the amount of the elapsed time measured by the ping program.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.4
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• pp.1911-1918
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• 2011

Internet banking, electronic financial services and internet telephony service can be available on smart phone recently. In this case, more robust authentication mechanisms should be provided for enhancing security on it. In this study, a facial biometric ID based one-time password generation mechanism is designed and implemented for enhancing user authentication on smart phone. After capturing a facial biometric data using camera module on smart phone, it is sent to server to generate one-time biometric ID. Finally one-time password will be generated by client module after receiving the one time biometric ID based challenge token from the server. Using proposed biometric ID based one-time password mechanism, it is possible for us to provide more secure user authentication service on smart phone for SIP protocol.

• Journal of KIISE:Computer Systems and Theory
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• v.37 no.4
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• pp.226-238
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• 2010

OpenSSL is an open-source library implementing SSL that is a secure communication protocol. However, the library has a severe vulnerability that its security information can be easily exposed to malicious software when the library is used in a form of shared library on Linux and UNIX operating systems. We propose a scheme to attack the vulnerability of the OpenSSL library. The scheme injects codes into a running client program to execute the following attacks on the vulnerability in a SSL handshake. First, when a client sends a server a list of cryptographic algorithms that the client is willing to support, our scheme replaces all algorithms in the list with a specific algorithm. Such a replacement causes the server to select the specific algorithm. Second, the scheme steals a key for data encryption and decryption when the key is generated. Then the key is sent to an outside attacker. After that, the outside attacker decrypts encrypted data that has been transmitted between the client and the server, using the specified algorithm and the key. To show that our scheme is realizable, we perform an experiment of collecting encrypted login data that an ftp client using the OpenSSL shared library sends its server and then decrypting the login data.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.47 no.1
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• pp.15-21
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• 2010

This paper proposes the multimedia fingerprinting code insertion algorithm when video content is distributed in P2P environment, and designs the collusion codebook SRP(Small RISC Processor) embedded system for the collusion attack prevention. In the implemented system, it is detecting the fingerprinting code inserted in the video content of the client user in which it requests an upload to the web server and in which if it is certified content then transmitted to the streaming server then the implemented system allowed to distribute in P2P network. On the contrary, if it detects the collusion code, than the implemented system blocks to transmit the video content to the streaming server and discontinues to distribute in P2P network. And also it traces the colluders who generate the collusion code and participates in the collusion attack. The collusion code of the averaging attack is generated with 10% of BIBD code v. Based on the generated collusion code, the codebook is designed. As a result, when the insert quantity of the fingerprinting code is 0.15% upper in bitplane 0~3 of the Y(luminance) element of I-frame at the video compression of ASF for a streaming service and MP4 for an offline offer of video content, the correlation coefficient of the inserted original code and the detected code is above 0.15. At the correlation coefficient is above 0.1 then the detection ratio of the collusion code is 38%, and is above 0.2 then the trace ratio of the colluder is 20%.

• The KIPS Transactions:PartD
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• v.13D no.6 s.109
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• pp.839-846
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• 2006

Context-aware adaptive service for overcoming the limitations of wireless devices and maintaining adequate service levels in changing environments is becoming an important issue. However, most existing studies concentrate on an adaptation module on the client, proxy, or server. These existing studies thus suffer from the problem of having the workload concentrated on a single system when the number of users increases md, and as a result, increases the response time to a user's request. Therefore, in this paper the adaptation module is dispersed and arranged over the client, proxy, and server. The module monitors the contort of the system and creates a proposition as to the dispersed adaptation system in which the most adequate system for conducting operations. Through this method faster adaptation work will be made possible even when the numbers of users increase, and more stable system operation is made possible as the workload is divided. In order to evaluate the proposed system, a prototype is constructed and dispersed operations are tested using multimedia based learning content, simulating server overload and compared the response times and system stability with the existing server based adaptation method. The effectiveness of the system is confirmed through this results.