• Proceedings of the Korea Society for Industrial Systems Conference
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• 2003.11a
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• pp.239-250
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• 2003

In this research, we propose a hybrid group decision support mechanism (H-GDSM) based on Fuzzy AHP (Analytic Hierarchy Process) and FCM (Fuzzy Cognitive Map). The AHP elicits a corresponding priority vector interpreting the preferred information among the decision makers. Corresponding vector was composed of the pairwise comparison values of a set of objects. Since pairwise comparison values are the judgments obtained from an appropriate semantic scale. However, AHP couldn't represent the causal relationship among information, which were used by decision makers. In contrast to AHP, FCM could represent the causal relationship among variables or information. Therefore, FCMs were successfully developed and used in several ill-structured domains, such as strategic decision-making, policy making, and simulations. Nonetheless, many researchers used subjective and voluntary inputs to simulate the FCM. As a result of subjective inputs, it couldn't avoid the rebukes of businessman. To overcome these limitations, we incorporated the Fuzzy membership functions, AHP and FCM into a H-GDSM. In contrast to current AHP methods and FCMs, the H-GDSM method developed herein could concurrently tackle the pairwise comparison involving causal relationships under a group decision-making environment. The strengths and contributions of our mechanism were 1) handling of qualitative knowledge and causal relationships, 2) extraction of objective input value to simulate the FCM, 3) multi-phase group decision support based on H-GDSM. To validate our proposed mechanism we developed a simple prototype system to support negotiation-based decisions in electronic commerce (EC).

• Journal of Korea Society of Industrial Information Systems
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• v.19 no.5
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• pp.103-115
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• 2014

Mobile-Office is the IT office that enables people handle their business anywhere and anytime without going to head office. It has propagated rapidly in domestic and foreign companies as the users who use mobile terminal such as smartphone have increased sharply. Mobile-Office is emerging as a new way of conducting business. It requires business environment to be changed to improve business efficiency, as fast-growing mobile-based economies emerges. Small and medium-sized companies's utilization ability for advanced IT technology is insufficient, and limitations exist on capacity of building and investment. They need different development methodologies and utilization methods. The purpose of this study is not only to consider the previous business environment problem on accessibility, mobility, effectiveness, complexity and consolidation, but to search more efficient methods for introducing applications to utilize various smart devices and websites with minimum investment in R&D.

• Journal of the Korean Institute of Intelligent Systems
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• v.14 no.3
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• pp.285-289
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• 2004

Recently, due to the high development of the internet, needs for multimedia streams such as digital audio and video is increasing much more. In case of transmitting multimedia streams using the User Datagram Protocol (UDP), it may cause starvation of TCP traffic on the same transmission path, thus resulting in congestion collapse and enormous delay because UDP does not perform TCP-like congestion control. Because of this problem, diverse researches are being conducted on new transmission schemes and protocols intended to efficiently reduce the transmission delay of real-time multimedia streams and perform congestion control. The TCP-friendly congestion control schemes can be classified into the window-based congestion control, which uses the general congestion window management function, and the rate-based congestion control, which dynamically adjusts transmission rate by using TCP modeling equations and the like. In this paper, we suggest the square-root congestion avoidance algorithm with the hybrid TCP-friendly congestion control scheme which the window-based and rate-based congestion controls are dealt with in a combined way. We apply the proposed algorithm to the existing TEAR. We simulate the performance of the proposed TEAR by using NS, and the result shows that it gives better improvement in the stability needed for providing congestion control than the existing TEAR.

• Journal of the Korean Institute of Intelligent Systems
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• v.20 no.3
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• pp.343-347
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• 2010

This paper presents an efficient image recognition method using the hybrid coefficient measure of correlation and distance. The correlation coefficient is applied to measure the statistical similarity by using Pearson coefficient, and distance coefficient is also applied to measure the spacial similarity by using city-block. The total similarity among images is calculated by extending the similarity between the feature vectors, then the feature vectors can be extracted by PCA and ICA, respectively. The proposed method has been applied to the problem for recognizing the 960(30 persons * 4 expressions * 2 lights * 4 poses) facial images of 40*50 pixels. The experimental results show that the proposed method of ICA has a superior recognition performances than the method using PCA, and is affected less by the environmental influences so as lighting.

• Smart Structures and Systems
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• v.23 no.6
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• pp.589-613
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• 2019

Cables are prone to vibration due to their low inherent damping characteristics. Recently, negative stiffness dampers have gained attentions, because of their promising energy dissipation ability. The viscous inertial mass damper (termed as VIMD hereinafter) can be viewed as one realization of the inerter. It is formed by paralleling an inertial mass part with a common energy dissipation element (e.g., viscous element) and able to provide pseudo-negative stiffness properties to flexible systems such as cables. A previous study examined the potential of IMD to enhance the damping of stay cables. Because there are already models for common energy dissipation elements, the key to establish a general model for IMD is to propose an analytical model of the rotary mass component. In this paper, the characteristics of the rotary mass and the proposed analytical model have been evaluated by the numerical and experimental tests. First, a series of harmonic tests are conducted to show the performance and properties of the IMD only having the rotary mass. Then, the mechanism of nonlinearities is analyzed, and an analytical model is introduced and validated by comparing with the experimental data. Finally, a real-time hybrid simulation test is conducted with a physical IMD specimen and cable numerical substructure under distributed sinusoidal excitation. The results show that the chosen model of the rotary mass part can provide better estimation on the damper's performance, and it is better to use it to form a general analytical model of IMD. On the other hand, the simplified damper model is accurate for the preliminary simulation of the cable responses.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.1
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• pp.406-434
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• 2019

In general, an information security approach estimates the risk, where the risk is to occur due to an unusual event, and the associated consequences for cloud organization. Information Security and Risk Management (ISRA) practices vary among cloud organizations and disciplines. There are several approaches to compare existing risk management methods for cloud organizations but their scope is limited considering stereo type criteria, rather than developing an agent based task that considers all aspects of the associated risk. It is the lack of considering all existing renowned risk management frameworks, their proper comparison, and agent techniques that motivates this research. This paper proposes Agent Based Information Security Framework for Hybrid Cloud Computing as an all-inclusive method including cloud related methods to review and compare existing different renowned methods for cloud computing risk issues and by adding new tasks from surveyed methods. The concepts of software agent and intelligent agent have been introduced that fetch/collect accurate information used in framework and to develop a decision system that facilitates the organization to take decision against threat agent on the basis of information provided by the security agents. The scope of this research primarily considers risk assessment methods that focus on assets, potential threats, vulnerabilities and their associated measures to calculate consequences. After in-depth comparison of renowned ISRA methods with ABISF, we have found that ISO/IEC 27005:2011 is the most appropriate approach among existing ISRA methods. The proposed framework was implemented using fuzzy inference system based upon fuzzy set theory, and MATLAB(R) fuzzy logic rules were used to test the framework. The fuzzy results confirm that proposed framework could be used for information security in cloud computing environment.

• Journal of IKEEE
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• v.22 no.4
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• pp.1073-1078
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• 2018

As interest in the 4th Industrial Revolution increases, the CPS, in which things existing in the reality and things existing in the virtual interact with each other, is attracting attention as an important technology. Complex systems such as electric vehicles, autonomous driving, smart factories, and smart grid system are considered as core technology fields of the 4th Industrial Revolution, and many types of research have been conducted to develop it. The reliability of the system is directly related to the safety of people in case of the autonomous driving, and verification of the actual vehicle's hardware and software of ADAS is essential. In this paper, we proposed distributed simulation middleware supporting HILS for reliable verification of the complex hybrid systems.

• Journal of IKEEE
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• v.23 no.1
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• pp.289-294
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• 2019

At present, domestic small islands mainly supply electric power using diesel generators. However, diesel generators can cause instability of the power system due to slow response on power load fluctuation, and cause environmental problems due to the emission of carbon gas by using fossil fuels. In order to overcome this problem, this paper proposes a method to establish an optimal microgrid by introducing solar power, wind power, and energy storage device to Chujado Island, which is supplied with electric power through a diesel generator. The economical optimum capacity of each distributed power source is calculated by using HOMER (Hybrid Optimization Model for Multiple Energy Resources) program and the proposed microgrid is validated by using PSCAD/EMTDC (Power Systems Computer Aided Design/ Electromagnetic Transients including DC) program which can analyze system stability.

• The Journal of the Acoustical Society of Korea
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• v.40 no.6
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• pp.626-648
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• 2021

Domestically, demands for multi-purpose performance venues which accommodate various performance genres have increased. However, those venues have limited capability and confined to a primary performance. The present work investigated various methods for controlling the acoustics of room for required performance genres by reviewing aurally presented and published materials. The method of varying the acoustics of a space is called Variable Acoustics, and adjusted in either passive and active ways. Passive control encompasses variable absorption, variable volume, coupled volume, and canopy reflectors, where the acoustics of a room is controlled in an architectural way. Active control includes In-line, Regenerative, and Hybrid systems where the acoustics of a room is manipulated electronically. The mechanism and application of each passive control system in existing venues are reviewed and their pros and cons are discussed. Also, the concept of each active systems and product applications are looked at through literature reviews. Lastly, some considerations that need to be taken into in the planning and design stage of a multi-purpose hall using Variable Acoustics are suggested.

• Journal of Ocean Engineering and Technology
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• v.30 no.1
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• pp.57-67
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• 2016

As a new technical approach, an attempt was made to realize a photovoltaic system for an eco-environmental leisure ship by simultaneously actuating nine photovoltaic solar panels in association with the application of a sail-controlling system using wind energy. In this approach, the photovoltaic system consisted of a solar module, an inverter, a battery, and the relevant components, while the sail-controlling device was equipped with sail up/down and mast turning systems. The previously mentioned eco-environmental leisure ship utilizes a photovoltaic hybrid system that uses solar and wind energy as renewable energy sources. Furthermore, this research included a performance evaluation of the manufactured prototype, the acquisition of the purposed quantity values, and development of the purposed items. The significant items, including the sail up/down speed (seconds) and mast turning angle (degrees) were evaluated for a performance test. A wind direction sensitivity of 90% and maximum instant charging power of 900 W were also obtained in the process of the performance evaluation. In addition, the maximum sail time was also evaluated in order to acquire the optimum value. The performance evaluation showed that the prototype with a photovoltaic hybrid system was suitable for sailing an eco-environmental leisure ship using solar and wind energy.