• Journal of the Korea Society of Computer and Information
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• v.10 no.4 s.36
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• pp.355-364
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• 2005

An example of such a new device is a mobile phone. The demand for wireless data communication is growing rapidly. However, agencies have not yet completed the standardization of the markup language. Due to the evolution of the Mobile Device, the agencies in this field have provided different data formats with each Mobile Device Platform. Traditionally, contents are hand-tailored to suit the target devices. A key problem is that the characteristics and capabilities of mobile devices are too diverse to service the most suitable mobile contents. Owing to this problem, the need for a reusable document description language increases. In this paper, we defined Template file that is common data to service mobile devices. We proposed method that could be effective wireless web service though design and the implementation of the Call Manager & the XSL Generator. In the methodology, when requesting wireless internet service, the mobile device finds out Markup language and hardware specification of the mobile device through the Call Manager component supports. The XSL Generator component creates XSL file dynamically that is the most suitable to device. Finally, contents is serviced to each device by XSLT.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.26 no.2
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• pp.203-209
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• 2016

According to the wear detection history for the steam generator tubes in the nuclear power plant, the outer tubes inside the steam generator have more problems on the flow-induced vibration than inner tubes. Many researchers and engineers have used a specified added mass coefficient for a given tube array during the design stage of the steam generator even though the coefficient is not constant for entire tube in cylindrical shell. The aim of this study is to find out the distribution of added mass coefficients for each tube along the radial location. When numbers of tubes inside a cylindrical shell are increased, values of added mass coefficients are also increased. Added mass coefficients at outer tubes are less than those of inner tubes and they are decreased with increasing the gap between the outermost tube and the cylindrical shell. It also turns out when the gap between the outermost tube and the cylindrical shell approaches infinite value, the added mass coefficient converges to an asymptotic value of given tube array in a free fluid field.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.12
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• pp.25-34
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• 2006

In this paper, a method of designing the pitch control algorithm for the wind turbine generator system (WTGS) and results of nonlinear simulation are presented. For this, the WTGS is treated as a multibody system and the blade element and momentum theory are adopted to model the aerodynamic force and torque acting the rotor blades. For the purpose of controller design, the WTGS is approximated to 1 DOF system using the fact that the WTGS is eventually a constrained multibody system. Then a classical PID controller is designed and used to regulate the rotational speed of the generator. FORTRAN based nonlinear simulation program is written and used to evaluate the performance of the proposed controller at the various wind scenario and operational modes.

• Fire Science and Engineering
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• v.19 no.2 s.58
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• pp.69-74
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• 2005

A study of the utilization of inert gas generator(IGG) that generates a large amount of inert gas for the fire extinguishing equipment was performed. In this study, the fire extinction performance of gas generated from a 1GG which is implemented to a gas turbine was investigated. A simulated mixture gas of which composition is the same as that of the gas generated from ICG was used in all experiments. First, the extinction concentration was measured using a cup burner method. The extinction design concentration and the volume of extinction space was calculated by applying the obtained extinction concentration to a method recommended by NFPA 2001. In practical respects, the fire extinction performance of IGG-generated gas was confirmed through the fire suppression experiment within a $2m\times2m\times2m$ room.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.7C
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• pp.640-648
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• 2009

Summation generator with high period and high linear complexity can be easily implemented by a simple hardware or software and it is proper to apply in mobile security system for ubiquitous environments. However the generator has been some weaknesses from Dawson's divided-and-conquer attack, Golic's correlation attack and Meier's fast correlation attack. In this paper, we propose an improved version($2^{128}$security level) of $E_0$algorithm, CVC-NSG(Circular-Clock-Controlled - Nonlinear Summation Generator), which partially replaces LFSRs with nonlinear FSRs and controls the irregular clock to reinforce it's own weaknesses. Finally, we analyze our proposed design in terms of security and performance.

• Journal of the Korea Institute of Military Science and Technology
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• v.18 no.5
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• pp.485-491
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• 2015

In this study, the experimental and analytical investigation on structural integrity evaluation of spline shaft of self propelled artillery' generator were carried out. For this work, macro and microstructure fractography of spline shaft were observed. According to the results of the structure analysis and simulation, the shaft was redesigned and optimized. To improve the stiffness and shear stress, the material was changed from the SNCM220 to SNCM439 and surface roughness and protective coating treatment are changed to increase the stress relaxation, respectively. From the result of the torsion test of shaft and accelerated life test of generator, the shaft of a SNCM439 with heat-treatment(Q/T) and electroless nickel plating was superior quality reliability and durability than the others. Therefore, modeling and simulation corresponded well with the experimental result and structural safety was confirmed by generator performing.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.05a
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• pp.313-316
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• 2003

This paper presents stand-alone electric power generator using bridge vibration for charging system of health monitoring sensor unit of bridge structure. In this paper, a novel electric power generator utilizing vertical vibration is proposed, which has minimum effect of armature reaction, and the related mechanical and electrical design equations are obtained and then a pilot electric power generator has been implemented. Moreover, the free oscillation test reveals that diode characteristics of rectifier is dominant factor in charging process. Also, simulation results with the Namhae bridge data showed the validity and effectiveness for stand-alone electric power generation.

• The Journal of the Korea Contents Association
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• v.8 no.7
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• pp.53-57
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• 2008

The discretized saw-tooth map with the 16-bit finite precision which is one of the 1-dimensional chaotic maps is designed, and the circuit of chaotic binary sequence generator using the discretized saw-tooth map is presented also in this brief. The real implementation of designed chaotic map is accomplished by connecting the input and output lines exactly according to the simplified Boolean functions of output variables obtained from truth table which is discretized. The random binary output sequences generated by mLFSR generator were used for the inputs of descretized saw-tooth map, and, by the descretized map, chaotic binary sequence which has more long period of 16 times minimally is generated as a results.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.413-416
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• 2009

For the liquid rocket engine, the gas generator oxidizer shut-off valve which supplies the oxidizer to a gas generator needs structural safety under the internal pressure, which is higher than the chamber pressure. In this study, static stress analyses of the various design in the vicinity of the region where the stress is concentrated were performed for designing the lightweight valve, A lightest model of which the concentrated stress does not exceed the yield criteria has been suggested. Also, whole size effect of the valve on the concentrated stress was investigated.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.50 no.7
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• pp.324-332
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• 2001

In this paper, it is suggested that the selection method of parameter of Power System Stabilizer(PSS) with robustness in low frequency oscillation for Static VAR Compensator(SVC) using a Real Variable Elitism Genetic Algorithm(RVEGA). A SVC, one of the Flexible AC Transmission System(FACTS), constructed by a fixed capacitor(FC) and a thyristor controlled reactor(TCR), is designed and implemented to improve the damping of a synchronous generator, as well as controlling the system voltage. The proposed PSS parameters are optimized using RVEGA in order to maintain optimal operation of generator under the various operating conditions. To decrease the computational time, real variable string is adopted. To verify the robustness of the proposed method, we considered the dynamic response of generator speed deviation and generator terminal voltage by applying a power fluctuation and three-phase fault at heavy load, normal load and light load. Thus, we prove the usefulness of proposed method to improve the stability of single machine-infinite bus with SVC system.