• Proceedings of the Korea Information Processing Society Conference
• /
• 2024.05a
• /
• pp.283-284
• /
• 2024

디지털 워터마킹은 디지털 컨텐츠에 정보를 삽입하는 기술이다. 종래의 디지털 워터마킹 기술은 견고성과 비가시성 사이에 트레이드오프 관계를 가지고, 변형 및 노이즈 공격 등에 취약하다. 본 논문에서는 호스트 이미지의 비가시성을 보장하면서 효율적인 공격 탐지와 소유자 식별이 가능한 워터마킹 기법을 제안한다. 제안한 방식은 주파수 분할 기반의 계층적 워터마킹 및 공격 탐지 시그니처 삽입을 통해 비가시성을 보장하며 용량과 견고성 측면에서 종래의 방법보다 향상된 성능을 보였다. 실험 결과에 따르면 종래의 디지털 워터마크가 무력화되는 왜곡 공격 상황에서 공격 탐지 시그니처 검출이 가능하여 워터마크 공격을 탐지하고 소유자를 식별할 수 있었다.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2024.05a
• /
• pp.181-182
• /
• 2024

IoT(Internet of Things) 기기의 수가 급격히 증가하면서 무선 네트워크로 펌웨어와 데이터를 다운받아 업데이트하는 FOTA(Firmware Over-The-Air) 기술이 중요해지고 있다. 그러나, 종래 퍼징 기술은 펌웨어 취약점을 탐지할 때 요구되는 컴퓨팅 파워와 메모리가 커서 한정적인 자원을 지닌 IoT 기기에 적합하지 않다. 따라서 본 연구에서는 펌웨어 업데이트 파일에서 기존에 검증된 부분을 제외하고 업데이트된 부분만을 퍼징하는 부분 퍼징(Partial fuzzing) 기법을 제안한다. 실험 결과에 따르면 제안한 부분 퍼징 기법이 종래의 기법 대비 3 분 더 빨리 11 개의 크래시를 찾았고, 10 분의 퍼징 시간 동안 평균 1,044 (2 unique) 크래시를 추가로 발견했으며 평균 메모리 사용량을 232(KIB) 줄일 수 있었다.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2024.05a
• /
• pp.308-309
• /
• 2024

IoT(Internet of Things) 기기를 대상으로 하는 보안 위협이 증가하면서 IoT 정보의 기밀성 유지가 중요한 과제로 떠오르고 있다. 따라서 경량, 저가, 저전력 IoT 환경에서 높은 보안 수준을 유지할 수 있는 암호화 방법이 필요하다. 본 연구에서 AES(Advanced Encryption Standard)와 SAES(Simplified AES)를 이용한 이중 암호화 기법을 제안한다. 제안하는 기법은 SAES 로 평문 메시지 전체를 블록 단위로 암호화하고, 각 암호문 블록의 일부 비트를 추출해 AES 로 재암호화한다. 실험 결과에 따르면, 제안한 경량 이중 암호화 기법이 종래 방식보다 암호문의 크기를 32% 줄일 수 있었다.

• International Journal of Internet, Broadcasting and Communication
• /
• v.16 no.3
• /
• pp.77-84
• /
• 2024

Aberration is still a problem for making augmented reality displays. The existing methods to solve this problem are either slow and inefficient, consume too much battery, or are too complex for straightforward implementation. There are still some problems with image quality, and users may suffer from eye strain and headaches because the images provided to each eye lack accuracy, causing the brain to receive mismatched cues between the vergence and accommodation of the eyes. In this paper, we implemented a computer simulation of an optical aberration using Zernike polynomials which are defocus, trefoil, coma, and spherical. The research showed that these optical aberrations impact the Point Spread Function (PSF) and Modulation Transfer Function (MTF). We employed the phase conjugate technique to mitigate aberrations. The findings revealed that the most significant impact on the PSF and MTF comes from the influence of spherical aberration and coma aberration.

• Journal of the Korean Society of Industry Convergence
• /
• v.27 no.4_2
• /
• pp.973-980
• /
• 2024

Dependence of dynamic fracture path on loading velocity was observed from experimental results based on the three point bending fracture in cast iron. In this study, 3D and 2D numerical simulations are used to evaluate singular stress fields near crack tip and fracture mechanics parameters. Moving finite element technique, 2D and 3D Delauney automatic mesh generation and contact-noncontact evaluation is introduced into the numerical method. Dynamic fracture thoughness is decreased with increase of impact loading velocity. Fracture mode-ratio corresponds to initial kink angle of fracture path. The numerical result shows that the maximum hoop stress criterion cannot be applied to dynamic fracture of cast iron.

• Asia Marketing Journal
• /
• v.15 no.3
• /
• pp.1-14
• /
• 2013

Our research brings managerial insights for developing new digital convergence of devices and services. To explain the phenomenon of device and service convergence, we combine two different approaches from separate research fields: a perceptual mapping technique generally used for segmentation in marketing and associative network analysis mobilized to understanding network structure of core and peripheral as well as the information mediating role of nodes in network science. By combining these two approaches, we provide an in-depth analysis of the associations among devices and services by assessing the centrality of device and service nodes in an associative network. This is done by examining the connections between these services and devices as well as investigating the role of mediation in the combined device-service associative network. Our results based on bi-partite network analysis of survey responses from 250 Internet Protocol (IP) television viewers show which device and which service will play the major role in future device and service convergence as well as which characteristics and functionalities have to be incorporated into future convergence. Among the devices, the mobile handset with the betweenness centrality of 0.26 appears to be the device that would lead future device convergence. Among the services, wireless broadband with the betweenness centrality of 0.276 appears to be the service on which future service convergence needs to be developed. This result is quite unexpected, since wireless broadband has a lower penetration rate than other services, such as fixed broadband and cable TV. In addition, we indicate the possibility of converging devices, such as personal digital assistant (PDA) and mobile handset, and services, such as IPTV and mobile Internet, into wireless broadband services in the future.

• Journal of applied mathematics & informatics
• /
• v.17 no.1_2_3
• /
• pp.59-72
• /
• 2005

The auxiliary principle is used to suggest and analyze some iterative methods for solving solving hemivariational inequalities under mild conditions. The results obtained in this paper can be considered as a novel application of the auxiliary principle technique. Since hemivariational in­equalities include variational inequalities and nonlinear optimization problems as special cases, our results continue to hold for these problems.

• Communications of the Korean Mathematical Society
• /
• v.22 no.1
• /
• pp.53-64
• /
• 2007

In this paper, we apply the generalized quasilinearization technique to a forced Duffing equation with three-point mixed nonlinear nonlocal boundary conditions and obtain sequences of upper and lower solutions converging monotonically and quadratically to the unique solution of the problem.

• Bulletin of the Korean Mathematical Society
• /
• v.27 no.2
• /
• pp.165-172
• /
• 1990

In this paper, we study a method which speeds up the convergence of monotone iterations and give some numerical examples of the types (2) and (3). In [2] this method has been applied to a system of hyperbolic differential equations with initial and boundary conditions.

• Wind and Structures
• /
• v.22 no.3
• /
• pp.349-368
• /
• 2016

A preconditioning technique is presented for a simultaneous solution to wind-membrane interaction. In the simultaneous equations, a linear elastic model was employed to deal with the fluid-structure data transfer at the interface. A Lagrange multiplier was introduced to impose the specified boundary conditions at the interface and strongly coupled simultaneous equations are derived after space and time discretization. An initial linear elastic model preconditioner and modified one were derived by treating the linearized elastic model equation as a saddle point problem, respectively. Accordingly, initial and modified fluid-structure interaction (FSI) preconditioner for the simultaneous equations were derived based on the initial and modified linear elastic model preconditioners, respectively. Wind-membrane interaction analysis by the proposed preconditioners, for two and three dimensional membranous structures respectively, was performed. Comparison was made between the performance of initial and modified preconditioners by comparing parameters such as iteration numbers, relative residuals and convergence in FSI computation. The results show that the proposed preconditioning technique greatly improves calculation accuracy and efficiency. The priority of the modified FSI preconditioner is verified. The proposed preconditioning technique provides an efficient solution procedure and paves the way for practical application of simultaneous solution for wind-structure interaction computation.