• Journal of Electrical Engineering and Technology
• /
• v.8 no.2
• /
• pp.262-270
• /
• 2013

A boundary protection method for power distribution line based on equivalent boundary effect is presented in this paper. In the proposed scheme, the equivalent resonance component with a certain central frequency is sleeve-mounted at the beginning of protected zone. The 'Line Boundary' is built by using boundary effect, which is created by introducing impedance in the primary-side of line. The 'Line Boundary' is significantly different from line wave impedance. Therefore, the boundary protection principle can be applied to power distribution line without line traps. To analyze the frequency characteristic corresponding to traveling-waves of introducing impedance in the primary-side of line, distributed parameters model of equivalent resonance component is established. The results of PSCAD/EMTDC simulation prove the obvious difference of voltage high frequency component between internal faults and external faults due to equivalent resonance component, and validate the scheme.

• Proceedings of the KIEE Conference
• /
• 2000.07b
• /
• pp.772-774
• /
• 2000

The objective of a cathodic protection system (CP) is to protect the buried metallic structure against the corrosion caused by chemical reaction between the buried structure and the surrounding medium, such as soil. This paper presents a boundary element application to determine the optimal impressed current densities in a cathodic protection system. The potential within the electrolyte is described by the Laplace's equation with nonlinear boundary conditions which are enforced based on experimentally determined electrochemical polarization curves. The optimal impressed current densities are determined in order to minimize the power supply for protection. The solution is obtained by using the conjugate gradient method in which the governing equations and the protecting conditions are taken into account by the penalty function method. Numerical example are presented to demonstrate the practical applicability of the proposed method.

• Proceedings of the Korean Society of Marine Engineers Conference
• /
• 2005.06a
• /
• pp.395-400
• /
• 2005

The ship hull part is always exposed to severe corrosive environments. Therefore, it should be protected in appropriate ways to reduce corrosion problems. So there are two effective methods in order to protect the corrosion of ship hull. One is the paint coating as a barrier between steel and electrolyte (seawater) and the other is the cathodic protection(CP) supplying protection current. In the conventional design process of the cathodic protection system the required current densities of protected materials have been used. However, the anode position of field or laboratory experiment for obtaining the required current density for CP is significantly different from anode position for real structures. Therefore, the recent CP design must consider the optimum anode position for potential distribution equally over the ship hull. The CP design companies in the advanced countries can obtain the potential distribution results on the cathodic materials by using the computer analysis module. This study would show how to approach the potential analysis in the field of corrosion engineering. The computer program can predict the under protection area on the structure when the boundary condition and analysis procedure are reasonable. In this analysis the polarization curve is converted to the boundary condition in material data.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.20 no.2
• /
• pp.139-144
• /
• 2011

This paper presents a boundary element application to determine the optimal impressed current densities at defect position on the pipe line. In this protection paint, enough current must be impressed to lower the potential distribution on the metal surface to the critical values. The optimal impressed current densities are determined in order to minimize the power supply for protection. This inverse problem was formulated by employing the boundary element method. Since the system of linear equations obtained was ill-conditioned, including singular value decomposition, conjugate gradient method were applied and the accuracies of these estimation. Several numerical examples are presented to demonstrate the practical applicability of the proposed method.

• Corrosion Science and Technology
• /
• v.7 no.4
• /
• pp.197-200
• /
• 2008

In this paper, physical scale modeling was employed to identify the configurations of ICCP system and the electric field signatures. Computational boundary element modeling technique has been used to simulate the performance of the CP system and to predict the associated electric fields signatures. The optimization methods combined with the computer models and physical scale modeling will be presented here, which enable the optimum system design to be achieved both in terms of the location and current output of the anode but also in the location of reference electrodes for impressed current cathodic protection(ICCP) systems. The combined methodology was utilized to determine optimal placement of ICCP components (anodes and reference electrodes) and to evaluate performance of ICCP system for the 2%, 10% and 14% wetted hull coatings loss. The objective is to design the system to minimise the electric field while at the same time provide adequate protection for the ship. The results show that experimental scale modeling and computational modeling techniques can be used in concert to design an optimum ICCP system and to provide information for quickly analysis of the system and its surrounding environment.

• International Journal of Aerospace System Engineering
• /
• v.2 no.2
• /
• pp.73-78
• /
• 2015

According to the characteristic of carrier-based aircraft, the method of solving safe set during arresting landing is discussed in this paper based on optimal control and invariant set theory. The safe sets of carrier aircraft are evaluated in different states on the characteristic of longitudinal augmented system by using the level set method. Then, the influence on the boundary of safe set under various factors is analyzed. At last, the maneuverability envelope protection is established based on the corresponding theory, and the validity of the system is verified through simulation. The results demonstrate preliminarily that: compared with mass and thrust, the elevator is the greatest influence factor for the boundary of safe set; the dynamic trajectory of carrier-based aircraft can be located at the interior of safe set effectively with the maneuverability envelope protection.

• Corrosion Science and Technology
• /
• v.8 no.5
• /
• pp.177-183
• /
• 2009

There are two effective methods in use to protect ship ballast tank against corrosion. One is paint coating and the other cathodic protection(CP). The conventional cathodic protection design has mainly relied on the expert's experience. During the last two decades computer modeling has been significantly developed as an advanced design technology for cathoidic protection systems not only for ships, but also for offshore structures. However the present computer modeling of cathodic protection systems have some limitations simulating corrosion in the ballast tank with a deteriorated coating. In this study, "coating breakdown factor" considering coating degradation states with time has been attempted to improve the cathodic protection modeling using the data from literatures.

• International Journal of Control, Automation, and Systems
• /
• v.4 no.1
• /
• pp.105-112
• /
• 2006

The main function of a reactor protection system is to maintain the reactor core integrity and the reactor coolant system pressure boundary. Generally, the reactor protection system adopts the 2-out-of-m redundant architecture to assure a reliable operation. This paper describes the safety assessment of a digital reactor protection system using the fault tree analysis technique. The fault tree technique can be expressed in terms of combinations of the basic event failures such as the random hardware failures, common cause failures, operator errors, and the fault tolerance mechanisms implemented in the reactor protection system. In this paper, a prediction method of the hardware failure rate is suggested for a digital reactor protection system, and applied to the reactor protection system being developed in Korea to identify design weak points from a safety point of view.

• Strategy21
• /
• s.37
• /
• pp.193-241
• /
• 2015

China, Japan and Korea are the world's top 10 energy consumers, and so very interested in the development of seabed hydrocarbon resources in order to meet their energy demands. The East China Sea is the tri-junction area where three countries' entitlements on the maritime boundaries are overlapped. There are abundant oil reserves in the East China Sea, and therefore competitions among countries are growing to get control of them. Although these countries have concluded the bilateral agreements to jointly develop resources in the East China Sea, they do not function as well. Because joint development and management of seabed petroleum resources can lead to stable development system, and to lower possibility of legal and political disputes, the needs for joint development agreement among three countries are urgent. Meanwhile, Northeast Asian seas are semi-closed seas, which are geographically closed and vulnerable to marine pollution. Moreover there are a lot of nuclear power plants in coastal area, and seabed petroleum resources are being developed. So it is likely to occur nuclear and oil spill accidents. Fukushima nuclear disaster and Bohai Bay oil spill accident in 2011 are the cases to exhibit the potential of major marine pollution accidents in this area. It is anticipated that the risks become higher because power plants and offshore oil platforms are extending gradually. Therefore, the ways to seek the joint marine environmental protection agreement focused on regulation of nuclear power plant and offshore oil platform have to be considered. In this paper, we try to find the way to make joint development and joint environmental protection agreement in Northeast Asian seas. We concentrate on the measure to drive joint development of seabed petroleum deposits in East China Sea's overlap area, despite of maritime delimitation and territorial disputes, and we try to drive joint marine environmental protection system to respond to marine pollution and accidents due to offshore oil platform and nuclear power plants. Through these consideration, we seek solutions to deal with lack of energy, disputes of maritime territorial and boundary delimitation, and marine pollution in Northeast Asia.

• JSTS:Journal of Semiconductor Technology and Science
• /
• v.12 no.3
• /
• pp.286-292
• /
• 2012

Scan techniques are almost mandatorily adopted in designing current System-on-a-Chip (SoC) to enhance testability, but inadvertently secret keys can be stolen through the scan test channels of crypto SoCs. An efficient scan design technique is proposed in this paper to protect the secret key of an Advanced Encryption Standard (AES) core embedded in an SoC. A new instruction is added to IEEE 1149.1 boundary scan to use a fake key instead of user key, in which the fake key is chosen with meticulous care to improve the testability as well. Our approach can be implemented as user defined logic with conventional boundary scan design, hence no modification is necessary to any crypto IP core. Conformance to the IEEE 1149.1 standards is completely preserved while yielding better performance of area, power, and fault coverage with highly robust protection of the secret user key.