• Journal of the Korea Institute of Information Security & Cryptology
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• v.30 no.3
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• pp.443-454
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• 2020

The JavaScript engine is a module that receives JavaScript code as input and processes it, among many functions that are loaded into web browsers and display web pages. Many fuzzing test studies have been conducted as vulnerabilities in JavaScript engines could threaten the system security of end-users running JavaScript through browsers. Some of them have increased fuzzing efficiency by guiding test coverage in JavaScript engines, but no coverage guided fuzzing of optimized, dynamically generated machine code was attempted. Optimized JavaScript codes are difficult to perform sufficient iterative testing through fuzzing due to the function of runtime guards to free the code in the event of exceptional control flow. To solve these problems, this paper proposes a method of performing fuzzing tests on optimized machine code by avoiding deoptimization. In addition, we propose a method to measure the coverage of runtime-guards by the dynamic binary instrumentation and to guide increment of runtime-guard coverage. In our experiment, our method has outperformed the existing method at two measures: runtime coverage and iteration by time.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.4 no.1
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• pp.219-226
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• 2000

In this paper, we design and implement a IF(intermediate frequency) module for WLL(wireless local loop) CDMA(code division multiple access) basestation. The implemented IF transceiver is consists of transmitter, receiver and local oscillator. The considered signal bandwidth is 10 MHz and the local carrier frequency is 40 MHz. As test results, the If transmitter output power is -5dBm $\pm3dB$when the baseband input is -10dBm $\pm3dB$, and the IF receiver output power is -10dBm $\pm3dB$when the IF input is -5dBm $\pm3dB$. Also the AGC(automatic gain control) circuit has dynamic range of 9 dB from -7dBm to +2dBm with output power 2dBm. And the group delay characteristic is analyzed by comparing the phase delay from 1 MHz to 5 MHz and the phase distortion is very low. We can conclude that this IF system can be applied to high speed data rate communication system.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.7B
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• pp.628-637
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• 2003

This paper describes a novel multiplexing scheme for delay-sensitive multiple VBR-coded bit streams in live multimedia service offered to high-speed networks. The primary goal of multiplexing in this paper is to keep delay limits of each bit streams and to enhance network resource utilization when they no multiplexed and transmitted over network. For this aim, this paper presents a dynamical control scheme which does not cause violation of any delay constraints to each bit steam. The scheme is based on the assumption that recent behavior of the each bit scream has high correlation with near-term future behavior. Such property is used to make as flat as possible by both temporal averaging on a stream-by-stream and spatial averaging is introduced when multiple VBR-coded bit streams are multiplexed. The effectiveness of the scheme is evaluated by several simulation using an MPEG-coded video trace of Star_wars and it is shown that the proposed scheme can effectively reduce the feat rate md coefficient of variation of the multiplexed transmission rate.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.9
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• pp.1081-1094
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• 2016

KREONET is a principal national R&E network running by KISTI in Korea. It uniquely provides production research network services for around 200 non-profit research and educational organizations, based on hybrid (IP and non-IP) network infrastructure. However, KREONET is limited to meet various needs of new network services for advanced Science & Technology (S&T) users because its infrastructure is inherently derived form classical hardware-based, fixed and closed environments. So, KREONET-S is designed to provide advanced S&T services to catch up with time-to-research and time-to-collaboration. In this paper, we present a system architecture of KREONET-S based on network infrastructure that consists of data and control planes separately. Furthermore, we propose and describe VDN service which is capable of building a virtual dedicate & bandwidth-guaranteed network for S&T group dynamically. we implement VDN application on KREONET-S and then perform performance analysis for proving that KREONET-S system and VDN application can be a good solutions to cope with new network paradigms for various advanced S&T applications and users.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.32 no.5
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• pp.50-57
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• 2004

For the application of structural health monitoring such as AE detection, a stabilized FBG sensor system with wide dynamic range was proposed. A tunable Fabry-Perot filter with narrow free spectral range(FSR) was used to simplify the multiplexing demodulator for FBG vibration sensors. Stabilization controlling system was also developed for the maintenance of maximum sensitivity of the sensors. In order to verify the performance of the proposed FBG vibration sensor system, we measured sensitivity, and the system showed the average sensitivity of 256 $n{\in}_{mas}/{\sqrt{Hz}}$. Finally, multi-points vibration tests using in-line FBG sensors were conducted to validate the multiplexing performance of the FBG system.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.3
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• pp.1378-1387
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• 2013

Histogram equalization, which stretches the dynamic range of intensity, is the most common method for enhancing the contrast of image. Contrast limited adaptive histogram equalization(CLAHE), proposed by K. Zuierveld, has two key parameters: block size and clip limit. These parameters mainly control image quality, but have been heuristically determined by user. In this paper, we propose a novel method of determining two parameters of CLAHE using entropy of image. The key idea is based on the characteristics of entropy curves: clip limit vs entropy and block size vs entropy. Clip limit and block size are determined at the point with maximum curvature on entropy curve. Experimental results show that the proposed method improves images with very low contrast.

• Journal of the Korea institute for structural maintenance and inspection
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• v.20 no.4
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• pp.1-8
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• 2016

Recently, buildings tend to be large size, complex shape and functional. As the size of buildings is becoming massive, the need for structural health monitoring(SHM) technique is ever-increasing. Various SHM techniques have been studied for buildings which have different dynamic characteristics and are influenced by various external loads. Generally, the visual inspection and non-destructive test for an accessible point of structures are performed by experts. But nowadays, the system is required which is online measurement and detect risk elements automatically without blind spots on structures. In this study, in order to consider the response of non-linear structures, proposed a signal feature extraction and the adaptive threshold setting algorithm utilized to determine the abnormal behavior by using statistical methods such as control chart, root mean square deviation, generalized extremely distribution. And the performance of that was validated by using the acceleration response of structures during earthquakes measuring system of forced vibration tests and actual operation.

• The Transactions of the Korea Information Processing Society
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• v.7 no.11S
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• pp.3732-3838
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• 2000

As the Internet sites and users have rapidly been increased, the development for search engines has also been accelerated to satisfy users' expectations. As the result, not only the action of collecting documents through many search engines gave hosts workload, but also regular updating all the information is needed since information is newly added. With the circumstances, the necessity of the technology to collect massive information in hosts has been increased for the speed which is a basic requisite of search systems, and for more accurate collection of documents. Also, the role of search engines grows bigger for Internet users' various demands and flexible process through World Wide Web. In this paper, we design and implement a robot agent and a remote control system which doesn't give an excessive workload on a target server and makes the collection of documents done in a short period by considering an average workload rate on the target server and the rate of the workload that a robot experience in collection time, after we compare and analyze the existing Robot Agent Systems and supplement their weak points.

• The Transactions of the Korea Information Processing Society
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• v.4 no.10
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• pp.2521-2532
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• 1997

The next generation internet protocol, IPv6, have been developed by the IETF according to the requirements of enhancement of classic IP protocols to satisfy the lack of Internet address space as well as the support of multimedia applications. This paper presents an implementation of IPv6 protocols on the Windows NT kernel environment. In this work, we developed and also tested the basic functions, required for operating as an IPv6 host, such as IPv6 header processing, IPv6 address handling, control message processing, group membership processing and neighbor discovery functions. The implemented IPv6 protocol driver module is connected to the lower network interface card through NDIS, a standard network interface. And this driver module that operates within kernel, is implemented as it is connected to upper user applications and lower NDIS using dispatch and lower-edge functions. The developed IPv6 protocol driver can provide not only enhanced performance because it is implemented in kernel mode, but also convenience of usage to the application developers because it gives user interface as a dynamic link library.

• Macromolecular Research
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• v.15 no.5
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• pp.437-442
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• 2007

Poly(ethylene glycol) methyl ether (PEG)-poly(${\beta}$-amino ester) (PAE) block copolymers were synthesized using a Michael-type step polymerization, and the construction of pH-sensitive polymeric micelles (PM) investigated. The ${\beta}$-amino ester block of the block copolymers functioned as a pH-sensitive moiety as well as a hydrophobic block in relation to the ionization of PAE, while PEG acted as a hydrophilic block, regardless of ionization. The synthesized polymers were characterized using $^1H-NMR$, with their molecular weights measured using gel permeation chromatography. The $pK_b$ values of the pH-sensitive polymers were measured using a titration method. The pH-sensitivity and critical micelle concentration (CMC) of the block copolymers in PBS solution were estimated using fluorescence spectroscopy. The pH dependent micellization behaviors with various bisacrylate esters varied within a narrow pH range. The critical micelle concentration at pH 7.4 decreased from 0.032 to 0.004 mg/mL on increasing the number of methyl group in the bisacrylate from 4 to 10. Also, the particle size of the block copolymer micelles was determined using dynamic light scattering (DLS). The DLS results revealed the micelles had an average size below 100 nm. These pH-sensitive polymeric micelles may be good carriers for the delivery of an anticancer drug.