• The Transactions of the Korean Institute of Electrical Engineers A
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• v.55 no.12
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• pp.505-513
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• 2006

One of the major reasons for recent blackout, like August 14, 2003 blackout in the US and Canada has been insufficient voltage/reactive power support. For the stable reactive power management, a new approach for the voltage monitoring and control structure is required in the market environment. This paper proposes the effective localized-voltage control scheme using the information from pilot buses at each zone. In this paper, the steady state voltage monitoring and control (SSVMC) is adopted and illustrated for the voltage control scheme during steady state because it is thought as the systemic algorithm to explain voltage profile phenomenon before and after contingencies. And the concept of electrical distance is applied to simultaneously achieve both clustering the voltage control zone, and selecting the pilot bus as the representative node at each control zone. Applying SSVMC based on the structure with clustering and pilot bus enables system operators to monitor and understand the system condition much more easily, to monitor and control the voltage in real-time more manageably, and to respond quickly to a disturbance. The proposed voltage control scheme has been tested on the IEEE 14-bus system with the numerical analysis to examine the system reliability and structure efficiency.

• Journal of the Korean Institute of Telematics and Electronics
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• v.27 no.2
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• pp.118-125
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• 1990

An optimal file allocation algorithm which seeks optimal solution of file allocation problem for efficient management and operation of information files in distributed computer system is proposed. Since file allocation time in practical applications that have many computer sites is tool long, the problem size has to be reduced and computation time is improved by using preassignment conditio. A new method which calculate appriasal value for accurrate value for accurrate representation of assigned state is proposed and the selection criteria to candidate nodes for rapid determination of allocation are given. By using selection criteria, file allocation is determined and final appraisal value represent total cost of assigned state.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2017.05a
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• pp.258-259
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• 2017

Recently, as science and technology is very growing, wire and wireless communication is merged and interconnected. Therefore, advanced internet technology allow all kinds of communication to integrate with heterogeneous device and sensors. The representative example is smart home network based on internet of things. Communication surroundings under IoT services are more complex. Conventional encryption techniques can't provide to IoT application because of its limited resources such as small memory capacity and low computing power. In this paper, we analyzed authentication procedure between home gateway and node in sensor under smart home network.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.23 no.6
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• pp.659-665
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• 2010

The finite element method(FEM) is proven to be an effective approximate method of structural analysis if proper element types and meshes are chosen, and recently, the method is often applied to solve complex dynamic and nonlinear problems. A properly chosen element type and mesh yields reliable results for dynamic finite element structural analysis. However, dynamic behavior of a structure may include unpredictably large strains in some parts of the structure, and using the initial mesh throughout the duration of a dynamic analysis may include some elements to go through strains beyond the elements' reliable limits. Thus, the finite element mesh for a dynamic analysis must be dynamically adaptive, and considering the rapid process of analysis in real time, the dynamically adaptive finite element mesh generating schemes must be computationally efficient. In this paper, a computationally efficient dynamically adaptive finite element mesh generation scheme for dynamic analyses of structures is described. The concept of representative strain value is used for error estimates and the refinements of meshes use combinations of the h-method(node movement) and the r-method(element division). The shape coefficient for element mesh is used to correct overly distorted elements. The validity of the scheme is shown through a cantilever beam example under a concentrated load with varying values. The example shows reasonable accuracy and efficient computing time. Furthermore, the study shows the potential for the scheme's effective use in complex structural dynamic problems such as those under seismic or erratic wind loads.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.8
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• pp.985-994
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• 2012

This paper presents the real channel measurements and investigates their statistical characterization in wireless body area network(WBAN). In on-/off body channel, the measurements are performed with some representative human movements for considering human movements. Moreover, three signal transmission schemes with outage constraint are studied for getting total power consumption in each transmission scheme. Using the real channel measurements, between theoretical and realistic simulation are compared. This paper shows that power efficiency is improved through cooperative communication, and how much position of sensor node and human movement affect signal transmission power.

• Journal of the Korean Society of Clothing and Textiles
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• v.43 no.4
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• pp.521-531
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• 2019

Uigwe Banchado are paintings of court events and royal ceremonies of the Joseon dynasty. The paintings record national events and ceremonial rituals performed by the Joseon royal family, such as marriages, celebrations, enthronements, processions to royal tombs, and archery ceremonies. This record provides a combination of information about the event's appearance, including preparation, procedure, people involved, reproductions worn by the participants, and the items used at that time. Through the realistic depictions painted in the Uigwe Banchado, in particular, one can grasp the scene of events at the time and reproduce the diverse attire worn by participants in the event. Based on 31 representative Uigwe Banchado, 550 knowledge nodes were written. These include 31 royal protocols, 41 attires, 136 clothes, 8 storage facilities, 120 objects, 55 people, 33 places and 83 concepts. The meaningful relationships between each node can be explored via a network graph. Digital illustrations of the 41 attires were created to aid in the understanding of Joseon dynasty royal ceremonial ritual attire.

• International journal of advanced smart convergence
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• v.12 no.1
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• pp.41-52
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• 2023

The purpose of this study is to review the proposed solutions to the Blockchain trilemma put forward by various research scholars and to draw conclusions by comparing the findings of each study. We found that the models so far developed either compromise scalability, decentralization, or security. The first model compromises decentralization. By partially centralizing the network, transaction processing speed can be improved, but security strength is weakened. Examples of this include Algorand and EOS. Because Algorand randomly selects the node that decides the consensus, the security of Algorand is better than EOS, wherein a designated selector decides. The second model recognizes that scalability causes a delay in speed when transactions are included in a block, reducing the system's efficiency. Compromising scalability makes it possible to increase decentralization. Representative examples include Bitcoin and Ethereum. Bitcoin is more vital than Ethereum in terms of security, but in terms of scalability, Ethereum is superior to Bitcoin. In the third model, information is stored and managed through various procedures at the expense of security. The application case is to weaken security by applying a layer 1 or 2 solution that stores and reroutes information. The expected effect of this study is to provide a new perspective on the trilemma debate and to stimulate interest in continued research into the problem.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2022.06a
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• pp.155-156
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• 2022

Efficient operation of ships can transport cargo to ports safer and faster, and reduce fuel costs. Therefore, in this study, the pattern was analyzed using AIS data of ships passing near Busan Port, a representative port in Korea. The analysis of vessel traffic patterns was approached with a grid-based node generation method, which can be used for research such as optimal route and route prediction.

• Computers and Concrete
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• v.32 no.5
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• pp.527-541
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• 2023

This paper emphasizes the use of CFT columns in frame structures subjected to strong horizontal forces and shows that the efficiency of using CFT columns is increased when the plastic design approach is adopted. Because the plastic design approach is based on redistribution of the force of the internal member, a double node for the rotational degrees of freedom, where the adjacent two rotational degrees of freedom can be connected by a non-dimensional spring element, is designed and implemented into the formulation. In addition, an accompanying criterion is considered in order to make it possible to describe the continuous moment redistribution in members connected to a nodal point up to a complete plastic state. The efficiency of CFT columns is reviewed in comparison with RC columns in terms of the cost and the resistance capacity, as defined by a P-M interaction diagram. Three representative frame structures are considered and the obtained results show that the most efficient and economical design can be expected when the use of CFT columns is considered on the basis of the plastic design, especially when a frame structure is subjected to significant horizontal forces, as in a high-rise building.

• Nuclear Engineering and Technology
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• v.56 no.3
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• pp.980-992
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• 2024

Steam line break accident (SLB) in the nuclear reactor is one of the representative Non-LOCA accidents in which thermal-hydraulics and neutron kinetics are strongly coupled each other. Thus, the multi-scale and multi-physics approach is applied in this study in order to examine a realistic safety margin. An entire reactor coolant system is modelled by system scale node, whereas sub-channel scale resolution is applied for the region of interest such as the reactor core. Fuel performance code is extended to consider full core pin-wise fuel behaviour. The MARU platform is developed for easy integration of the codes to be coupled. An initial stage of the steam line break accident is simulated on the MARU platform. As cold coolant is injected from the cold leg into the reactor pressure vessel, the power increases due to the moderator feedback. Three-dimensional coolant and fuel behaviour are qualitatively visualized for easy comprehension. Moreover, quantitative investigation is added by focusing on the enhancement of safety margin by means of comparing the minimum departure from nucleate boiling ratio (MDNBR). Three factors contributing to the increase of the MDNBR are proposed: Various geometric parameters, realistic power distribution by neutron kinetics code, Radial coolant mixing including sub-channel physics model.