• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.5
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• pp.1640-1645
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• 2010

There exists an inconvenience that players of each instrument pass musical score in orchestra recital. In this paper, we implement the electronic musical score transmitting system that possible to hand sheet music automatically, using Mini - ITX and LCD Panel. We made them unite with a sheet music pair, and it was made and a message and data transmission were embodied using reliable TCP/IP socket communication. In this paper, the client hands sheet music automatic, and server implemented the manual function to manage each clients individually. Because one band can be managed by one Access file all together, it is easy to manage each band. Along with this, this system selects TCP/IP as the reliable transfer protocol that protect loss and errors.

• Aerospace Engineering and Technology
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• v.10 no.1
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• pp.45-53
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• 2011

This paper is technical review about Direct Sequence Spread Spectrum(DSSS) to apply in launch vehicle system. First, we introduce communication protocol(carrier frequency, code length, process gain, data rate, chip rate etc) about several application system using DSSS. And then, we survey and summarize the effect of doppler shift to the DSSS. The doppler shift is important error factor for PN code tracking in the fast moving system like launch vehicle. So, spread spectrum code acquisition technique for a direct sequence system in the presence of doppler effect must be investigated.

• Journal of the Korea Institute of Military Science and Technology
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• v.12 no.1
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• pp.88-96
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• 2009

Interoperation between heterogeneous simulators employs definition of standard protocols for data exchange and time synchronization among simulators. The High Level Architecture(HLA) is a specification of common services for such interoperation, which is approved as IEEE standard 1516. This paper presents the design and implementation of an interoperable adaptor which supports development of interoperable simulators under the IEEE 1516 HLA/RTI environment. The adaptor, KHLAAdaptor1516, is implemented as a library form which is linked to HLA-compliant simulators. Design of the adaptor employs a protocol conversion method, the model of which is finite state machine. KHLAAdaptor1516 allows developers to separate interoperable adaptors from stand-alone simulators. The interoperable adaptor manages mapping between HLA services and simulation messages for simulator, This separation increases robustness of a federation and reusability of simulators as well as alleviates much effort and time for maintenance.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.5
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• pp.815-825
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• 2015

DNP3(Distributed Network Protocol) is one of the most representative protocols which is used in SCADA(Supervisory Control and Data Acquisition) system. IEC 62351 is listing the integrity, confidentiality, availability and non-repudiation or accountability as the security requirement. However, IEEE Std. 1815 that is DNP3 standards does not define a mechanism for non-repudiation or accountability. In this paper, we propose a non-repudiation of origin technique about the sender of critical ASDU and implement the proposed scheme using software such as OpenSSL and SCADA source code library.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.08a
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• pp.91-94
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• 2008

As the mobile devices and the wireless networks have high-performance capabilities, it is possible to synchronize the spatio-temporal data of a server with the spatio-temporal data of a mobile device which are collected at a field. However, since the server process the synchronization which the model device requests, the whole synchronizations of mass mobile devices take long time. In this paper, we propose the scheme to process concurrently the synchronizations of mobile devices which does not conflict with others using the scheme of a multi-queue.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.49 no.6
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• pp.515-519
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• 2021

IEEE 1588 PTP is a precision time protocol in which two systems synchronize without the aid of GPS by exchanging packets including transmission/reception time information. In the time synchronization process, the propagation delay time can be calculated and the distance between the two systems can be measured using this. In this paper, we proposed a method to improve the distance measurement precision less than the modulation symbol period using the timing error information extracted from the preamble of the received packet. Computer simulations show that the distance measurement precision is proportional to the length of the preamble PN sequence and the signal-to-noise ratio.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.18 no.2
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• pp.117-128
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• 2008

Compared with the existing bar code system, RFID system has lots of advantages such as it identifies automatically massive objects. We might anticipate RFID technology will be a substitution for an optical bar code system in the near future. However, their feature that uses radio waves may cause various security problems. Many kinds of solutions have been researched to overcome these security problems. In this paper, we analyze the previous proposed protocols. And then, we categorize RFID authentication into two types according to the synchronization requirement between a Back-end Database and a Tag. In addition, we introduce the previous proposed approaches to tag search problem in RFID authentication. And we propose an efficient method which provides fast tag search by using membership test algorithm, a Bloom filter.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.9 no.5
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• pp.451-457
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• 2016

To improve security in the data communication field, many studies on the application of chaotic signals to encryption have been conducted in recent years. In this study, a new security protocol where the initial value sensitivity and noise similarity of chaotic signals have been applied to an RFID communication channel was designed. In the case of chaotic systems, if the initial values become identical, the same signals are generated at the same time after that point even though the two systems have been calculated independently. Therefore, an unpredictable security channel can be produced based on such characteristics. However, a security channel can be produced only when an initial value is shared in advance, and thus there is a potential problem of infringement during the transmission of the initial value. To resolve this problem, a method in which a certain proportion of new chaotic signals are applied to two chaotic systems for communication and are then synchronized after some time was proposed. This new method can conceal the initial value, and thus can resolve the problem of the existing communication method using chaotic signals. The designed method was verified with the encryption and decryption of images. It is expected that a more secure RFID system could be established by applying the communication protocol proposed in this study to insecure RFID communication channels.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.5B
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• pp.475-488
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• 2003

To prevent performance degradation of TCP due to packet losses in the smooth handoff by the route optimization extension of Mobile IP protocol, a buffering of packets at a base station is needed. A buffering of packets at a base station recovers those packets dropped during handoff by forwarding buffered packets at the old base station to the mobile user. But, when the mobile user moves to a congested base station in a new foreign subnetwork, those buffered packets forwarded by the old base station are dropped and TCP transmission performance of a mobile user in the congested base station degrades due to increased congestion by those forwarded burst packets. In this paper, considering the general case that a mobile user moves to a congested base station, we analyze the influence of packet buffering on TCP performance according to handoff arrival distribution for Drop-tail and RED (Random Early Detection) buffer management schemes. Simulation results show that RED scheme can reduce the congestion increased by those forwarded burst packets comparing Drop-Tail, but RED scheme cannot avoid Global Synchronization due to forwarded burst packets by the old base station and new buffer management scheme to avoid it is needed in Mobile IP based networks.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.38 no.9
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• pp.12-20
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• 2001

The ATM-PON has an important meaning at next generation access network because the equipment transmits various types of user traffic with a single platform through the passive optical splitter. Ranging is a technology to place all ONUs at the same virtual distance in order to provide the synchronization for the upstream signal in the ATM-PON based on the Time Division Multiplexing (TDM). In this paper, we review the merits of ATM PON and related protocol for the PON operation. We summarize and analyze the steps about the ranging protocol based on ITU-T G.983.1 and implement a simulator that can simulate the ranging procedure based on our modeling. In this paper, we can investigate time requirements of G.983.1 by using the simulator and find out the wasted rate of the bandwidth during the ranging procedure in order to know the influence for ONUs while ATM-PON is in-service. Also, we show that a new ranging scheme reducing window size can avoid the degradation of quality of service of ONUs in service with simulation.