• Journal of the Institute of Electronics Engineers of Korea TC
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• v.37 no.2
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• pp.17-23
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• 2000

Wireless link has high bit error rate compared with wired link and many users share this limited bandwidth. So it needs more powerful error control code and efficient media access control(MAC) to provide multimedia service reliably. In this paper we proposed efficient MAC frame format based on TDMA using mini-slot for request access. The number of mini-slots is variable based on the result of collision in the previous frame. This dynamic allocation of request mini-slots helps resolve the contention situation quickly and avoids the waste of bandwidth that may occur when there are several unneeded request mini-slots. The simulation results are also presented in terms of channel utilization, call blocking probability and cell transmission delay for mixed traffic environment.

• Journal of the Korea Society of Computer and Information
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• v.18 no.4
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• pp.153-160
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• 2013

Online game provides a kind of cyber money aden and game instruments, items in order to attract game users. Game users want stronger, better and higher-leveled items with competition. Demands and supplies on items are formed and the transactions are made. The problem is there happen frequently illegal behaviors in the process of transactions. Among these illegal behaviors, for using other's id and password without authorization and stealing items, rejecting to return assigned items, providing stolen item to other who knows the fact or destroying others' items, it is difficult to apply provisions on properties in the criminal code on them. Because the criminal code has a duty to prevent separation between substantial criminal behavior and regulations, it should reflect substantial cultures and values of the times. Therefore, property like items in cyber space can be considered as new property to need to be protect under the criminal code and it may be not an interpretation of expansion. The reason is it is practical and reasonable to judge whether propertiness can be established considering cyber space's unique characteristics. It is time to review propertiness of Article No. 346 according to the request of times of the digital age.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.4 no.1
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• pp.62-77
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• 2010

Emerging applications with high data rates will need to transport bulk data reliably in wireless sensor networks. ARQ (Automatic Repeat request) or Forward Error Correction (FEC) code schemes can be used to provide reliable transmission in a sensor network. However, the naive ARQ approach drops the whole frame, even though there is a bit error in the frame and the FEC at the bit level scheme may require a highly complex method to adjust the amount of FEC redundancy. We propose a bulk data transmission scheme based on erasure-resilient code in this paper to overcome these inefficiencies. The sender fragments bulk data into many small blocks, encodes the blocks with LT codes and packages several such blocks into a frame. The receiver only drops the corrupted blocks (compared to the entire frame) and the original data can be reconstructed if sufficient error-free blocks are received. An incidental benefit is that the frame error rate (FER) becomes irrelevant to frame size (error recovery). A frame can therefore be sufficiently large to provide high utilization of the wireless channel bandwidth without sacrificing the effectiveness of error recovery. The scheme has been implemented as a new data link layer in TinyOS, and evaluated through experiments in a testbed of Zigbex motes. Results show single hop transmission throughput can be improved by at least 20% under typical wireless channel conditions. It also reduces the transmission time of a reasonable range of size files by more than 30%, compared to a frame ARQ scheme. The total number of bytes sent by all nodes in the multi-hop communication is reduced by more than 60% compared to the frame ARQ scheme.

• Nuclear Engineering and Technology
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• v.54 no.9
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• pp.3317-3323
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• 2022

Half Value Layer calculations theoretically need prior specification of linear attenuation calculations, since the HVL value is derived by dividing ln(2) by the linear attenuation coefficient. The purpose of this study was to establish a direct computational model for determining HVL, a vital parameter in nuclear radiation safety studies and shielding material design. Accordingly, a typical gamma-ray transmission setup has been modeled using MCNPX (version 2.4.0) general-purpose Monte Carlo code. The MCNPX code's INPUT file was designed with two detection locations for primary and secondary gamma-rays, as well as attenuator material between those detectors. Next, Half Value Layer values of some well-known gamma-ray shielding materials such as lead and ordinary concrete have been calculated throughout a broad gamma-ray energy range. The outcomes were then compared to data from the National Institute of Standards and Technology. The Half Value Layer values obtained from MCNPX were reported to be highly compatible with the HVL values obtained from the NIST standard database. Our results indicate that the developed INPUT file may be utilized for direct computations of Half Value Layer values for nuclear safety assessments as well as medical radiation applications. In conclusion, advanced simulation methods such as the Monte Carlo code are very powerful and useful instruments that should be considered for daily radiation safety measures. The modeled MCNPX input file will be provided to the scientific community upon reasonable request.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.1
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• pp.843-847
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• 2005

The development of distributed application in the standardized CORBA(Common Object Request Broker Architecture) environments reduces the developing time and maintaining cost of the systems. Because of these advantages, the development of application is being progressed in the several fields using the CORBA environments. The programmers in the CORBA environments usually develop the application programs using the CORBA IDL(Interface Definition Language). The IDL files are compiled by IDL compiler and translated into the stubs and skeleton codes which are mapped onto particular target language. The stubs produced by IDL compilers processes the marshaling a data into message buffer. Before a stub can marshal a data into its message buffer, the stub must ensure that the buffer has at least enough free space to contain the encoded representation of the data. But, the stubs produced by typical IDL compilers check the amount of free buffer space before every atomic data is marshaled, and if necessary, expand the message buffer. These repeated tests are wasteful and incidence of overheads, especially if the marshal buffer space must be continually expanded. Thus, the performance of the application program may be poor. In this paper, we suggest the way that the stub code is maintain the enough free space before marshaling the data into message buffer. This methods were analyzes the overall storage requirements of every message that will be exchanged between client and server. For these analysis, in the Front End of compiler has maintain the information that the storage requirements and alignment constraints for data types. Thus, stub code is optimized and the performance of application program is increased.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.2
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• pp.895-900
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• 2011

To improve drawback of existing modulation method, in this paper, we propose the channel forecast method using adaptive modulation which can improve throughput of channel. This method adaptively changes modulation method to the change of channel environments. In proposed method, channel's characteristics are measured in realtime to determine code rate to the changes of demanded channel's bit error rate. If bit error rate is increased, this method reduce code rate to maintain maximum throughput. We analysis performance of proposed method by Matlab.

• The KIPS Transactions:PartC
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• v.19C no.1
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• pp.47-54
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• 2012

Sharing cross-site resources has been adopted by many recent websites in the forms of service-mashup and social network services. In this change, exploitation of the new vulnerabilities increases, which includes inserting malicious codes into the interaction points between clients and services instead of attacking the websites directly. In this paper, we present a system model to identify malicious script codes in the web contents by means of a remote verification while the web contents downloaded from multiple trusted origins are executed in a client's browser space. Our system classifies verification items according to the origin of request based on the information on the service code implementation and stores the verification results into three databases composed of white, gray, and black lists. Through the experimental evaluations, we have confirmed that our system provides clients with increased security by effectively detecting malicious scripts in the mashup web environment.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.29 no.4
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• pp.729-738
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• 2019

In this paper, we propose two-way authentication protocol between unmanned systems in tactical wireless networks in which long distance communications are not guaranteed due to a poor channel conditions. It is assumed that every unmanned systems have same random data set before they put into combat. The proposed protocol generates authentication code(AC) using random data that causes hash collision. The requester for authentication encrypts the materials such as their identifier, time-stamp, authentication code with the secret key. After then the requester transmits the encrypted message to the receiver. The receiver authenticates the requester by verifying the authentication code included in the request message. The performance analysis of the proposed protocol shows that it guarantees the security for various attack scenarios and efficiency in terms of communication overhead and computational cost. Furthermore, we analyzed the effect of the parameter values of the proposed protocol on the performance and suggest appropriate parameter value selection guide according to the level of security requirement.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.2126-2130
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• 2003

In the integrated systems, that is integrated digital TV(DTV) internet and home automation, like home server, is needed integration of digital TV video signal and computer graphic signal. The graphic signal is operating at the high speed and has time-divide-stream. So the re-request of data is not easy at the time of error detection. therefore EDAC algorithm is efficient. In this paper, we show a scheme, that is integration of graphic and dtv format signal for DTV monitor display. This paper also presents the efficiency error detection auto correction(EDAC) for conversion of graphics signal to DTV video signal. A presented EDAC algorithms use the modified hamming code for enhancing video quality and reliability. A EDAC algorithm of this paper can detect single error, double error, triple error and more error for preventing from incorrect correction. And it is not necessary an additional memory. In this paper The comparison between digital TV video signal and graphic signal, a EDAC algorithm and a design of conversion graphic signal to DTV signal with EDAC function in DTV system is described.

• Proceedings of the IEEK Conference
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• 2002.07a
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• pp.106-109
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• 2002

In the integrated systems, that is integrated digital TV(DTV) internet and home automation, like home server, is needed integration of digital TV video signal and computer graphic signal. The graphic signal is operating at the high speed and has time-divide-stream. So the re-request of data is not easy at the time of error detection. therefore EDAC algorithm is efficient. This paper presents the efficiency error detection auto correction(EDAC) for conversion of graphics signal to DTV video signal. A presented EDAC algorithms use the modified Hamming code for enhancing video quality and reliability. A EDAC algorithm of this paper can detect single error, double error, triple error and more error for preventing from incorrect correction. And it is not necessary an additional memory. In this paper The comparison between digital TV video signal and graphic signal, a EBAC algorithm and a design of conversion graphic signal to DTV signal with EDAC function is described.