• ETRI Journal
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• 제27권1호
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• pp.114-117
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• 2005

In this paper, we propose a key management scheme which can provide delivery of the key used to encrypt a digital content from the package server to digital rights management (DRM) clients in a secure manner. The proposed scheme can protect digital content from attacks since an encrypted digital content is sent by a package server and only DRM clients can decrypt the encrypted digital content. It protects the key not only from purchasers but also among the other principals who manage the distribution and license servers.

• Current Optics and Photonics
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• 제3권2호
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• pp.119-127
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• 2019

A new secret-key-sharing cryptosystem using optical phase-shifting digital holography is proposed. The proposed secret-key-sharing algorithm is based on the Diffie-Hellman key-exchange protocol, which is modified to an optical cipher system implemented by a two-step quadrature phase-shifting digital holographic encryption method using orthogonal polarization. Two unknown users' private keys are encrypted by two-step phase-shifting digital holography and are changed into three digital-hologram ciphers, which are stored by computer and are opened to a public communication network for secret-key-sharing. Two-step phase-shifting digital holograms are acquired by applying a phase step of 0 or ${\pi}/2$ in the reference beam's path. The encrypted digital hologram in the optical setup is a Fourier-transform hologram, and is recorded on CCDs with 256 quantized gray-level intensities. The digital hologram shows an analog-type noise-like randomized cipher with a two-dimensional array, which has a stronger security level than conventional electronic cryptography, due to the complexity of optical encryption, and protects against the possibility of a replay attack. Decryption with three encrypted digital holograms generates the same shared secret key for each user. Schematically, the proposed optical configuration has the advantage of producing a kind of double-key encryption, which can enhance security strength compared to the conventional Diffie-Hellman key-exchange protocol. Another advantage of the proposed secret-key-sharing cryptosystem is that it is free to change each user's private key in generating the public keys at any time. The proposed method is very effective cryptography when applied to a secret-key-exchange cryptosystem with high security strength.

• 대한치과교정학회지
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• 제53권2호
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• pp.77-88
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• 2023

Objective: To develop a method for generating three-dimensional (3D) digital models of the periodontal ligament (PDL) using 3D cone-beam computed tomography (CBCT) reconstruction and to evaluate the accuracy and agreement of the 3D PDL models in the measurement of periodontal bone loss. Methods: CBCT data collected from four patients with skeletal Class III malocclusion prior to periodontal surgery were reconstructed at three voxel sizes (0.2 mm, 0.25 mm, and 0.3 mm), and 3D tooth and alveolar bone models were generated to obtain digital PDL models for the maxillary and mandibular anterior teeth. Linear measurements of the alveolar bone crest obtained during periodontal surgery were compared with the digital measurements for assessment of the accuracy of the digital models. The agreement and reliability of the digital PDL models were analyzed using intra- and interexaminer correlation coefficients and Bland-Altman plots. Results: Digital models of the maxillary and mandibular anterior teeth, PDL, and alveolar bone of the four patients were successfully established. Relative to the intraoperative measurements, linear measurements obtained from the 3D digital models were accurate, and there were no significant differences among different voxel sizes at different sites. High diagnostic coincidence rates were found for the maxillary anterior teeth. The digital models showed high intra- and interexaminer agreement. Conclusions: Digital PDL models generated by 3D CBCT reconstruction can provide accurate and useful information regarding the alveolar crest morphology and facilitate reproducible measurements. This could assist clinicians in the evaluation of periodontal prognosis and establishment of an appropriate orthodontic treatment plan.

• 한국콘텐츠학회논문지
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• 제3권3호
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• pp.40-46
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• 2003

본 논문은 안전하지 못한 DCPS(Digital Contents Protection Systems)와 HOST 사이의 통신채널을 통해 서로 일치하는 암호 키를 생성하기 위한 공개키 적용을 위해 1차적으로 이산대수와 난수를 이용한 Diffie-Hellman 알고리즘을 적용하고, 2차적으로 키 관리 표준인 ANSI X9.17, ISO 8732와 PEM(Privacy-Enhanced Mail) 등에서 채택하고 있는 2개의 서로 다른 암호키를 통해 Triple DES를 적용하여 전송 선로상의 디지털콘텐츠의 안전한 전송을 수행한다. 이에 따라 설계한 정보보호 모듈은 Key Exchange 모듈, Key Derivation 모듈, Copy Protection Processing 모듈로 구성되었으며 사용자 인증 기능과 디지털콘텐츠 암호화 기능을 통해 인가되지 않은 사용자에 의한 디지털콘텐츠의 불법 복제 및 배포를 방지하교 전송선로상의 디지털콘텐츠를 보호할 수 있도록 하였다.

• 디지털산업정보학회논문지
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• 제4권2호
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• pp.21-28
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• 2008

There are some problems on the system that uses a password comprising a digital signature to identify the secret key owner under the public key infrastructure. For example, the password can be difficult to remember or easy to be disclosure, and users should make more complex password to protect it. A number of studies have been proceeded in order to overcome these defects using the fingerprint identification technologies, but they need to change the current standard of public key infrastructure. On the suggested private key escrow system, the private key can be withdrawn only through the enrollment and identification of a fingerprint template after it is saved to a reliable third system. Therefore, this new private key escrow system can remove previous inconveniences of managingthe private key on current public key infrastructure, and it exhibited superior results in terms of the evaluation items when compared with the integrated method of the existing fingerprint identification and public key infrastructure.

• Journal of Electrochemical Science and Technology
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• 제11권2호
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• pp.180-186
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• 2020

In this work, a metal-ligand solution (Cu-EDTA) was prepared based on the molecular precursor method and the solution was spin-coated onto 3D printed flexible photosensitive resin sheets. After being processed by microwave, a laser with a wavelength of 355 nm was utilized to scan the spin-coated sheets and then the sheets were immersed in an electroless copper plating solution to deposit copper wires. With the help of microwave processing, the adhesion between copper wires and substrate was improved which should result from the increase of roughness, decrease of contact angle and the consistent orientation of coated film according to the results of 3D profilometer and SEM. XPS results showed that copper seeds formed after laser scanning. Using the 3D printed flexible sheets as cathode and galvanized iron as anode, electrochemical machining was conducted.

• 대한치과교정학회지
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• 제54권3호
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• pp.171-184
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• 2024

Objective: This study aimed to determine the maxillary and mandibular basal bone regions and explore the three-dimensional positional relationship between the dentition and basal bone regions in patients with skeletal Class I and Class II malocclusions with mandibular retrusion. Methods: Eighty patients (40 each with Class I and Class II malocclusion) were enrolled. Maxillary and mandibular basal bone regions were determined using cone-beam computed tomography images. To measure the relationship between the dentition and basal bone region, the root position and root inclination were calculated using the coordinates of specific fixed points by a computer program written in Python. Results: In the Class II group, the mandibular anterior teeth inclined more labially (P < 0.05), with their apices positioned closer to the external boundary. The apex of the maxillary anterior root was positioned closer to the external boundary in both groups. Considering the molar region, the maxillary first molars tended to be more lingually inclined in females (P = 0.037), whereas the mandibular first molars were significantly more labially inclined in the Class II group (P < 0.05). Conclusions: Mandibular anterior teeth in Class II malocclusion exhibit a compensatory labial inclination trend with the crown and apex relative to the basal bone region when mandibular retrusion occurs. Moreover, as the root apices of the maxillary anterior teeth are much closer to the labial side in Class I and Class II malocclusion, the range of movement at the root apex should be limited to avoid extensive labial movement.

• Journal of the Optical Society of Korea
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• 제16권3호
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• pp.263-269
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• 2012

In this paper, we propose a new dual optical encryption method for binary data and secret key based on 2-step phase-shifting digital holography for a cryptographic system. Schematically, the proposed optical setup contains two Mach-Zehnder type interferometers. The inner interferometer is used for encrypting the secret key with the common key, while the outer interferometer is used for encrypting the binary data with the same secret key. 2-step phase-shifting digital holograms, which result in the encrypted data, are acquired by moving the PZT mirror with phase step of 0 or ${\pi}/2$ in the reference beam path of the Mach-Zehnder type interferometer. The digital hologram with the encrypted information is a Fourier transform hologram and is recorded on CCD with 256 gray level quantized intensities. Computer experiments show the results to be encryption and decryption carried out with the proposed method. The decryption of binary secret key image and data image is performed successfully.

• 한국정보처리학회논문지
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• 제6권11호
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• pp.3046-3059
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• 1999

Kailar Accountability Logic proposed for the accountability analysis of communication protocols that require accountability and use asymmetric key digital signature is extended for protocols that use symmetric key digital signature. A proposed electronic micropayment protocol that uses symmetric key digital signature is analyzed to illustrate the use of the extend logic in detecting its lack f accountability and suggesting changes to enhance its accountability.

• 한국IT서비스학회지
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• 제18권3호
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• pp.75-93
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• 2019

Digital twin technology is one of the key technologies to strengthen the competitiveness of manufacturing industry from the viewpoint of digital transformation in the era of $4^{th}$ industrial revolution. In this research, the important role in using digital twin technology in product design, This paper summarizes and empirically verifies the technical characteristics of digital twins, a key concept in the digital transition of the manufacturing industry. In this study, the technology characteristics of digital twin which is key concept in the digital transformation of manufacturing industry are summarized and empirically validated which factors militate a critical role in the use of digital twin technology in product design which is key area of product development. As a result of analysis, datafication, intellectualization which are characteristics of digital twin technology and task characteristics of product design influence Task Technology Fit (TTF) and Task Technology Fit (TTF) influences Technology (UTAUT) And finally, performance expectancy, effort expectancy, social influence and facilitating conditions affect usage intention.