• Proceedings of the KIEE Conference
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• 1999.11c
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• pp.700-702
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• 1999

The protection of data which we want to keep secret from invalid users has become a main topic nowadays. This paper introduces a encryption scheme for protecting speech signals from eavesdropping. The proposed encryption scheme adopts a secure voice cryptographic algorithm based on the scrambling in frequency band. In order to improve the conventional speech signal encryption scheme, we have randomly permuted DCT coefficients of speech signal. Simulation results are included to show the performance of the proposed algorithm for secure transmission of speech signals.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.596-602
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• 2008

Recently, there are increasing social needs for safe operation of trains and comforting for passengers. But lightning surges are responsible for serious disturbances such as damage, permanent degradation or temporary erratic operation of sensitive electronics circuits and systems. The purpose of this paper is to identify the requirements for Surge Protective Devices(SPDs) used in protecting railway signalling system. In this paper, we describes tests and requirements which establish methods for testing SPDs and determining their performance.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2001.06a
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• pp.143-148
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• 2001

ILSAC GF 3/API SL specification will be adopted in July 2001. The background and characteristics of GF3 specification is reviewed. GF3 specification consists of five new engine tests, two new bench tests and new limits on three bench tests currently used to define ILSAC GF-2. GF 3 engine oil shows good performance compared to GF2 engine oil in fuel efficiency, protecting ability the emission catalyst and high temperature oxidation stability.

• Journal of Korean Institute of Industrial Engineers
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• v.38 no.4
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• pp.258-261
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• 2012

In this paper, I propose a new asset allocation framework to cope with the dynamic nature of the financial market. The investment performance can be much improved by protecting the capital from the market crashes, and such crashes can be pre-identified with high probabilities by regime detection analysis via a specialized unsupervised machine learning technique.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2004.11a
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• pp.351-358
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• 2004

When fault occur in power systems, the protective relay plays a roles of protecting power system according to its setting values. There, it is very important that the protective relay have high selectivity performance in power system by correct setting the relays. This paper analyzed protect device protect cooperation or Transient stability and apply to Overcurrent relay in the real power system operation environment by using EDSA Program.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.4 no.2
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• pp.435-442
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• 2000

In the world of mobile agents, security aspects are extensively being discussed, with strong emphasis on how agents can be protected against malicious hosts and vice versa. This paper discusses methods for protecting an agent's route information from being misused by sites on route interested in gaining insight into the profile of the agent's owner or in obstructing the owner's original goal. Our methods provide visited sites with just a minimum of route information, but on the other hand allow sites to detect modifying attacks of preceding sites. Though, under noncolluding attacks, all methods presented provide a similar level of protection, the performance and the points of time differ when an attack can be detected.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.53 no.2
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• pp.70-76
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• 2004

The purpose of interlocking system in railway is to prevent the route for a train being set up and its protecting signal cleared if there were already another, conflicting route set up and the protecting signal for that route cleared. Recently, conventional relays circuitry in industrial field is replaced to computer-based control systems according to the advance of computer and communication technology. Therefore, interlocking systems in railway field are rapidly changing from existing relay-based interlocking system to computer-based electronic ones that executes the vital interlocking logic to assure the safety train routes at trackside signaling equipment room using electronic circuits. So it is very important to verify the performance of developed electronic interlocking system by plentiful laboratory testing before actually application in the railway system. However the laboratory testing in the present state of railway signaling is preformed individually by manual, so very much test time and cost are required. To solve these problems, we are developed the simulator for automatic interlocking inspection in this research. This simulator is able to operate on general personal computer and has following beneficial functions : automatic test sheet generation for inspection, automatic inspection execution and et al. The experiments are executed to test the feasibility of the developed simulator the experimental results have good agreements with the anticipated ones.

• Journal of Korea Multimedia Society
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• v.10 no.5
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• pp.668-678
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• 2007

The development of a wire and wireless communication technologies might permit easily accessing on various information. But, the easiness of accessing information has basically the problem of an unintended information outflow. An executable file which has key algorithms, data and resources for itself has very weak point in the security. Because the various information such as algorithms, data and resources is included in an executable file on embedded systems or virtual machines, the information outflow problem may appear more seriously. In this paper, we propose a technique which can be protecting the executable file contents for resolving the outflow problem through the encryption. Experimentally, we applied the proposed technique to EVM-the virtual machine for embedded system and verified it. Also, we tried a benchmark test for the proposed technique and obtained reasonable performance overhead.

• Transactions of the Korean Society of Automotive Engineers
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• v.13 no.2
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• pp.10-15
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• 2005

This study was initiated to evaluate the cooling performance of CAC (charged air cooler) and radiator in the engine room of a mini bus. So we had firstly to predict the mass flow rate coming from radiator grille and front bum per opening using computational fluid dynamics (CFD) simulation based on 3D configuration. And simulations were carried out for different cooling module layout and bum per opening hole size on sam e vehicle operating condition. Simulation results show that CAC cooling performance at reverse protecting plate-applying model was much efficient than that of the bum per opening hole size-increasing model in IMTD point of view. Part of the CFD simulation results was com pared to with experimental data. It was confirm ed that the CFD approach using STAR-CD based on pursuing no-com promise solution could provide design engineers with useful design information in the early design stage of vehicle development.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05b
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• pp.273-276
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• 2005

Polymer-modified mortar was developed for improving the performance of modified mortar which is mixed with polymer, and it is used for protecting and repairing materials of building because of their excellent performance to improve characteristics which are compressive strength, flexural strength, and adhesive strength. However, the performances of the polymer-modified mortars are highly affected by materials, which are polymer, mortar, and aggregates, and conditions which are curing environment and testing method. Furthermore, dry curing method after hydrated curing has been recommended to make strong polymer film for the best curing method to make excellent characteristics. In this report, We investigated the co-relation between curing methods and the characteristics, which are compressive strength, flexural strength, and adhesive strength for the polymer-modified mortars that are used in the domestic area.