• Tribology and Lubricants
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• v.27 no.1
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• pp.19-24
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• 2011

Metallic sintered brake pads are often applied to mid/high speed train due to their high strength and thermal characteristics. Imbalance contact between discs and pads can greatly influence the life span, one sided wear, discs attack/crack and threat the safety of the train during operation. In this research, we analyzed pressure/temperature distribution between brake pads and disks. Analyzed data had been verified and modified to conduct further tests of flexible brake pads with small/full-scale dynamo test. Flexible brake pads were installed to high speed train to conduct further tests to identify the differences between rigid brake pads and flexible brake pads. In result, Flexible brake pads showed outstanding disk thermal stability, one sided wear, noise and wear rate than rigid brake pad.

• KIPS Transactions on Computer and Communication Systems
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• v.7 no.2
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• pp.49-58
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• 2018

A certificate is a means to certify users by conducting the identification of the users, the prevention of forgery and alteration, and non-repudiation. Most people use an accredited certificate when they perform a task using online banking, and it is often used for the purpose of proving one's identity in issuing various certificates and making electronic payments in addition to online banking. At this time, the issued certificate exists in a file form on the disk, and it is possible to use the certificate issued in an existing device in a new device only if one copies it from the existing device. However, most certificate duplication methods are a method of duplication, entering an 8-16 digit verification code. This is inconvenient because one should enter the verification code and has a weakness that it is vulnerable to security issues. To solve this weakness, this study proposes a method for enhancing security certificate duplication in a multi-channel using TCP and BLE. The proposed method: 1) shares data can be mutually authenticated, using BLE Advertising data; and 2) encrypts the certificate with a symmetric key algorithm and delivers it after the certification of the device through an ECC-based electronic signature algorithm. As a result of the implementation of the proposed method in a mobile environment, it could defend against sniffing attacks, the area of security vulnerabilities in the existing methods and it was proven that it could increase security strength about $10^{41}$ times in an attempt of decoding through the method of substitution of brute force attack existing method.

• The Journal of the Korea Contents Association
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• v.10 no.3
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• pp.32-43
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• 2010

IPTV is an emerging technology that combines both broadcasting and tele-communication technologies, and provides various multi-media contents to the service subscribers. In general, IPTV broadcasters transmit scrambled signals (multi-media contents) to the paying subscribers, and the users within the acknowledged network descramble the signals using the smart-card. That is, users are verified through communication between STB (Set-Top Box) and smart-card. In 2004, Jiang et al. proposed a secure protocol regarding the verification process. The method has been modified and enhanced by several following research works. However, all the methods that have been proposed so far required modular exponentiation operations which may raise the smart-card costs. In this paper, we propose a new efficient mutual authentication and session-key establishment protocol using only hash functions and exclusive-or operations, and show that the proposed protocol is still secure under various security attacks.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.8 no.3
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• pp.549-555
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• 2007

A digital signature scheme provides integrity of the document, authentication and non-repudiation of a signer. Usually the key for digital signature is stored in hard disk or removal disk storage. The drawback of this approach is that the signer can let the agent to sign instead of the signer by providing the key information. It can be abused in applications such as electronic election. In this paper, we propose the undeniable biometric digital multi-signature scheme suitable for applications where the signer should not make an agent sign instead of himself/herself. The undeniable multi-signature scheme requires many signers and only the designated user can confirm the authenticity of multi-signature. The proposed scheme satisfies undeniable property and it is secure against active attacks such as modification and denial of the multi-signature by signers. As the key is generated through the signer's fingerprint image, it's also secure against signing by an agent.

• Journal of Korea Multimedia Society
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• v.14 no.3
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• pp.403-413
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• 2011

In this paper, we proposed a digital image watermarking technique using scrambled binary phase computer generated hologram in the discrete cosine transform(DCT) domain. For the embedding process of watermark. Using simulated annealing algorithm, we would generate a binary phase computer generated hologram(BPCGH) which can reconstruct hidden image perfectly instead of hidden image and encrypt it through the scramble operation. We multiply the encrypted watermark by the weight function and embed it into the DC coefficients in the DCT domain of host image and an inverse DCT is performed. For the extracting process of watermark, we compare the DC coefficients of watermarked image and original host image in the DCT domain and dividing it by the weight function and decrypt it using descramble operation. And we recover the hidden image by inverse Fourier transforming the decrypted watermark. Finally, we compute the correlation between the original hidden image and recovered hidden image to determine if a watermark exits in the host image. The proposed watermarking technique use the hologram information of hidden image which consist of binary values and scramble encryption technique so it is very secure and robust to the various external attacks such as compression, noises and cropping. We confirmed the advantages of the proposed watermarking technique through the computer simulations.