• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.9A
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• pp.1377-1386
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• 2000

As all delays resulting from the signaling network directly affect the response time of network management activity, all control informations have to be transported most efficiently. It is very important to know the performance of the signaling system not only because of smooth network operation but also because of efficient engineering of signaling networks. In this paper, we analyzed mean queueing delay of signaling link for ISUP signaling messages in common channel signaling system by using M[X]/G/1 and M[X]/D/1 batch arrival queueing system. This is because we modeled arrival process of the signaling messages as batch arrival process considering that many kinds of signaling messages are generated at short intervals when a call requests a connection. Analysis was carried out considering different call processing scenario based on ITU-T specification. We also described the numerical results from the different types of queueing models.

• The KIPS Transactions:PartA
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• v.8A no.4
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• pp.293-298
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• 2001

This paper propose the DoubleQ web server that classifies incoming requests according to whether the requested document is cached or not. Requests that demand a cached document is put into the Service Queue while other requests are added to the Defer Queue. The DoubleQ web server services requests that are in the Service Queue before it services requests in the Defer Queue. This strategy is used to reduce disk accesses that have been the predominant overhead of traditional web servers. Experimental results using synthetic data show that improvements in the average user response time and the throughput of the web server may be achieved.

• The Transactions of the Korean Institute of Power Electronics
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• v.23 no.6
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• pp.403-407
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• 2018

This study proposes a predictive direct power control method in a modular multilevel converter (MMC) high-voltage direct-current (HVDC) system. The conventional proportional integral (PI)-based control method uses a cascaded connection and requires an optimal gain selection procedure and additional decoupling scheme. However, the proposed control method has a simple structure for active/reactive power control due to the direct power control scheme and exhibits a fast dynamic response by predicting the future status of system variables and considering time delay. The effectiveness of the proposed method is verified by simulation results.

• Earthquakes and Structures
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• v.17 no.1
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• pp.1-15
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• 2019

In the structures with high level of ductility, the earthquake energy dissipation in structural components is an important factor that describes their seismic behavior. Since the connection details play a major role in the ductile behavior of structure, in this paper, the seismic response of 3-, 5- and 8-story steel special moment frames (SMFs) is investigated by considering the effects of panel zone modeling and the influence of forward-directivity near-field ground motions. To provide a reasonable comparison, selected records of both near and far-field are used in the nonlinear time-history analysis of models. The results of the comparison of the median maximum inter-story drift under excitation by near-field (NF) records and the far-field (FF) ground motions show that the inter-story drift demands can be obtained 3.47, 4.86 and 5.92 times in 3-, 5- and 8-story structures, respectively, undergoing near-field earthquakes.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.10
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• pp.8-15
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• 2018

This article investigates intelligent security integrated platform for real-time crime response and preventive crime prevention. This study analyzed intelligent crime prevention platform elements by analyzing crime prevention system/platform research, intelligent crime prevention research, and case study of municipality integrated operation center crime prevention system. Through this, we developed a practical intelligent security platform, and suggested a linkage with existing municipalities and smart city integrated platform system considering scalability. This enables CCTV monitoring, which is used only for existing post processing, to cope with real-time crime. It is expected that it will be able to solve the incidents in golden-time by grasping the precise position of the complainant not only in the outdoor but also indoors. It is also possible to provide citizen-centered crime-prevention social safety net information sharing service by enhancing citizen participation as well as improving control efficiency. The intelligent security platform has advantages that it is easy to spread the municipality because it is developed considering existing municipal system, smart city integration platform, and linkage and expansion with other security services.

• Advances in aircraft and spacecraft science
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• v.2 no.2
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• pp.125-168
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• 2015

Dynamic aeroelastic behavior of structurally nonlinear Joined Wings is presented. Three configurations, two characterized by a different location of the joint and one presenting a direct connection between the two wings (SensorCraft-like layout) are investigated. The snap-divergence is studied from a dynamic perspective in order to assess the real response of the configuration. The investigations also focus on the flutter occurrence (critical state) and postcritical phenomena. Limit Cycle Oscillations (LCOs) are observed, possibly followed by a loss of periodicity of the solution as speed is further increased. In some cases, it is also possible to ascertain the presence of period doubling (flip-) bifurcations. Differences between flutter (Hopf's bifurcation) speed evaluated with linear and nonlinear analyses are discussed in depth in order to understand if a linear (and thus computationally less intense) representation provides an acceptable estimate of the instability properties. Both frequency- and time-domain approaches are compared. Moreover, aerodynamic solvers based on the potential flow are critically examined. In particular, it is assessed in what measure more sophisticated aerodynamic and interface models impact the aeroelastic predictions. When the use of the tools gives different results, a physical interpretation of the leading mechanism generating the mismatch is provided. In particular, for PrandtlPlane-like configurations the aeroelastic response is very sensitive to the wake's shape. As a consequence, it is suggested that a more sophisticate modeling of the wake positively impacts the reliability of aerodynamic and aeroelastic analysis. For SensorCraft-like configurations some LCOs are characterized by a non-synchronous motion of the inner and outer portion of the lower wing: the wing's tip exhibits a small oscillation during the descending or ascending phase, whereas the mid-span station describes a sinusoidal-like trajectory in the time-domain.

• Structural Engineering and Mechanics
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• v.61 no.4
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• pp.527-538
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• 2017

The evaluation of the loss-of-support conditions of frictional beam-to-column connections using simplified numerical models describing the transverse response of a portal-like structure is presented in this paper considering the effects of the seismic-hazard disaggregation. Real earthquake time histories selected from European Strong-motion Database (ESD) are used to show the effects of the seismic-hazard disaggregation on the beam loss-of-support conditions. Seismic events are classified according to different values of magnitudes, epicentral distances and soil conditions (stiff or soft soil) highlighting the importance of considering the characteristics of the seismic input in the assessment of the loss-of-support conditions of frictional beam-to-column connections. A rigid and an elastic model of a frame of a precast industrial building (2-DoF portal-like model) are presented and adopted to find the minimum required friction coefficient to avoid sliding. Then, the mean value of the minimum required friction coefficient with an epicentral distance bin of 10 km is calculated and fitted with a linear function depending on the logarithm of the epicentral distance. A complete parametric analysis varying the horizontal and vertical period of vibration of the structure is performed. Results show that the loss-of-support condition is strongly influenced by magnitude, epicentral distance and soil conditions determining the frequency content of the earthquake time histories and the correlation between the maxima of the horizontal and vertical components. Moreover, as expected, dynamic characteristics of the structure have also a strong influence. Finally, the effect of the column nonlinear behavior (i.e. formation of plastic hinges at the base) is analyzed showing that the connection and the column are a series system where the maximum force is limited by the element having the minimum strength. Two different longitudinal reinforcement ratios are analyzed demonstrating that the column strength variation changes the system response.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.1
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• pp.172-178
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• 2014

This paper presents a new model of the Miller effect. The new Miller effect model is obtained from the accurate AC gain which includes the effect of the output capacitance of the common-source (CS) amplifier. The new Miller effect model consists of the series connection of a capacitance and a parallel RC circuit, one at the input and the other at the output. The frequency response obtained by the new Miller effect model is equal to that obtained from the original circuit. Even though the new model is complicated, the 3-dB frequency can be easily estimated by using the open-circuit time constants method without the node analysis.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.15 no.5
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• pp.1909-1928
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• 2021

At present, the Colombian government shares information on threats or vulnerabilities in the area of cybersecurity and cyberdefense, from other government agencies or departments, on an ad-hoc basis but not in real time, with the surveillance entities of the Government of the Republic of Colombia such as the Joint Command of Cybernetic Operations (CCOCI) and the Cybernetic Emergencies Response Team of Colombia (ColCERT). This research presents the MS-CSIRT (Management System Computer Security Incident Response Teams) methodology, that is used to unify the guidelines of a CSIRT towards a joint communication command in cybersecurity for the surveillance of Information Technology (IT), Technological Operations (TO), Internet Connection Sharing (ICS) or Internet of Things (IoT) infrastructures. This methodology evaluates the level of maturity, by means of a roadmap, to establish a CSIRT as a reference framework for government entities and as a guide for the areas of information security, IT and TO to strengthen the growth of the industry 4.0. This allows the organizations to draw a line of cybersecurity policy with scope, objectives, controls, metrics, procedures and use cases for the correct coordination between ColCERT and CCOCI, as support entities in cybersecurity, and the different companies (ICS, IoT, gas and energy, mining, maritime, agro-industrial, among others) or government agencies that use this methodology.

• Journal of KIISE:Information Networking
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• v.30 no.2
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• pp.244-251
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• 2003

As the Internet and wireless mobile communication is being widespread, the WAP (Wireless Application Protocol) that merges these two technologies has emerged. Also, the research of the WAP gateway that enables efficient processing of multiple user demands concurrently and prompt response to requests from various wireless devices has been performed in many working groups. The WAP stack is the most fundamental technology among these researches. In this paper, we implement the WAP container utilizing the JAVA's multithreading and applying to the connection pooling technique to manage the available resource in the container efficiently. Also, we design and implement the WTP(Wireless Transaction Protocol) layer and the UDP(User Datagram Protocol) layer based on the priority Policy. Our design and implementation showed the shorter waiting time than that of the existing FCFS(First-Come, First-Served) system in the transaction layer and its efficiency was proved through simulation.