• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송공학회 2006년도 학술대회
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• pp.307-312
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• 2006

Protection to the multimedia contents is inevitable to ensure that only authorized users be able to access the protected contents for consumption. Since protection mechanisms need to be designed efficiently by exploiting the type of the contents, we propose a protection scheme for the video bitstream encoded by Scalable Video Coding (SVC) technique. Our scheme exploits the property of SVC in which a video is encoded into spatial, temporal, and quality scalability layers. By applying our proposed protection scheme to the appropriate scalability layers we can effectively control the SVC contents completely or partially. Each layer can be flexibly protected with different encryption keys or even with different encryption algorithms. The algorithms that are used to protect each layer are described by the standardized protection description tool, which is the MPEG-21 Intellectual Property Management and Protection (IPMP) Components. In this paper, we present the design of the proposed layered SVC protection scheme, its implementation and experimental results. The experiment result shows that the proposed layered SVC protection scheme is very effective and can easily be applied.

• 한국정밀공학회지
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• 제23권5호
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• pp.170-176
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• 2006

Multi-layered laminate made of ceramic/composite have been developed to prevent penetration by high velocity impact. In this study, three-layered plates consisted of 1) cover layer (glass fiber reinforced polymer), 2) $Al_{2}O_{3}$, ceramic plate, and 3) backing plate (glass fiber reinforced polymer) were fabricated with various conditions and tested for their ballistic protection characteristic. The ceramic composite laminates, with thin backing plate, were completely penetrated by armor piercing projectile. The plate with inserted rubber between ceramic and backing plate showed excellent ballistic protection, though completely penetrated by the second shoot.

• Journal of Electrical Engineering and Technology
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• 제4권4호
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• pp.531-537
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• 2009

Lightning has a broad frequency spectrum from DC to a few MHz. Consequently, the high frequency performance of grounding systems for protection against lightning should be evaluated, with the distributed parameter circuit model in a uniform soil being used to simulate grounding impedances. This paper proposes a simulation method which applies the distributed parameter circuit model for the frequency-dependent impedance of vertically driven ground rods by considering multi-layered soil structures where ground rods are buried. The Matlab program was used to calculate the frequency-dependent ground impedances for two ground rods of different lengths. As a result, an increase of the length of ground rod is not always followed by a decrease of grounding impedance, at least at a high frequency. The results obtained using the newly proposed simulation method considering multi-layered soil structures are in good agreement with the measured results.

• 융합보안논문지
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• 제11권3호
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• pp.47-54
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• 2011

SVC(Scalable Video Coding) 영상을 보호하기 위해서는 두 가지 이슈를 고려해야 한다. 첫 번째로 영상의 어떤 부분을 암호화 할 것인지를 고려해야 하며 두 번째로 언제 영상에 암호를 적용 할 것인지를 고려해야 한다. 또한 암호화 적용에 따라 SVC의 미디어 확장성에 방해를 주어서는 안 된다. 본 논문은 상기 이슈들과 관련된 몇 가지 암호화 방식을 비교 분석하고 하이브리드 방식의 계층별 접근제어 메커니즘을 제안하였으며 개발 결과물에 대한 실험결과를 제시한다. 본 논문에서 제안한 메커니즘은 미디어의 확장성을 유지하면서 계층별 접근제어가 가능하며 영상의 재사용을 지원한다. 또한 인코더 대비 약 3% 이내의 보안 오버헤드가 발생하는 경량화된 기술로 적용성이 매우 높은 방식으로 설계되었다.

• Journal of Industrial and Engineering Chemistry
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• 제68권
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• pp.311-324
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• 2018

Herein,the Neodymium ion ($Nd^{3+}$) doped CoAl-LDH have been successfully prepared via co-precipitation method and was used as a precursor of Nd-doped CoAl-mixed metal oxides (MMO). The photocatalytic activity of doped LDH and MMO was investigated in the degradation of an azo dye, C.I. Acid Red 14, under visible light irradiation. DRS and PL analysis demonstrated decreasing in the band gap energy and recombination of photo-induced charge carriers of Nd-doped LDH and MMO compared with the pristine CoAL-LDH. Due to significant difference in photocatalytic performance. A power law empirical kinetic model was obtained for predicting the photocatalytic degradation efficiency.

• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송공학회 2010년도 추계학술대회
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• pp.78-81
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• 2010

In this paper, we propose an efficient and effective selective protection scheme to SVC that exploit the propagation of protection effect by protecting significant frames that can give the maximum visual quality degradation. We model SVC dependency coding structure as a directed acyclic graph which is characterized with an estimated visual quality value as the attribute at each node. The estimated visual quality is calculated by using our model based on the proportions of intra- and inter-predicted MBs, amounts of residual, and estimated visual quality of reference frames. The proposed selective protection scheme traverses the graph to find optimal protection paths that can give maximum visual quality degradation. Experimental results show that the proposed selective protection scheme reduces the required number of frames to be protected by 46.02% compared to the whole protection scheme and 27.56% compared to the layered protection scheme.

• Earthquakes and Structures
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• 제24권4호
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• pp.259-274
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• 2023

In this paper, mechanical properties of periodic foundation made of concrete and rubber are investigated by a parametric study using the finite element method (FEM). Periodic foundation is a special type of seismic isolation foundation used in civil engineering, which is inspired by the meso-scale structure of phononic crystals in solid-state physics. This type of foundation is capable of reducing the seismic wave propagating though the foundation, therefore providing additional protection for the structures. In the FEM analysis, layered periodic foundation is frequently modelled due to its simplicity in numerical modeling. However, the isolation effect of periodic foundation on nuclear power plant has not been fully discussed to the best knowledge of authors. In this work, we construct four numerical models of nuclear power plant with different foundations to investigate the seismic isolation effects of periodic foundations. The results show that the layered periodic foundation can increase the natural period of the nuclear power plant like traditional base isolation systems, which is beneficial to the structures. In addition, the seismic response of the nuclear power plant can also be effectively reduced in both vertical and horizontal directions when the frequencies of the incident waves fall into some specific frequency bandgaps of the periodic foundation. Furthermore, it is demonstrated that the layered periodic foundation can reduce the amplitude of the floor response spectrum, which plays an important role in the protection of the equipment.

• 한국물환경학회지
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• 제38권4호
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• pp.171-176
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• 2022

Recently, an autotrophic single-stage nitrogen removal (ASSNR) process based on the anaerobic ammonium oxidation (ANAMMOX) reaction has been proven as an economical ammonia treatment. It is highly evident that double-layered gel beads are a promising alternative to the natural biofilm for ASSNR because of the high mechanical strength of poly(vinyl alcohol) (PVA)/alginate structure and efficient protection of ANAMMOX bacteria from dissolved oxygen (DO) due to the thick outer layer. However, the thick outer layer results in severe mass transport limitation and consequent lowered bacterial activity. Therefore, the effects of the thickness of the outer layer on the overall reaction rate were tested in the biofilm model using AQUASIM for ammonia-oxidizing bacteria (AOB), nitrite-oxidizing bacteria (NOB) and ANAMMOX bacteria. A thickness of 0.5~1.0 mm is preferred for the maximum total nitrogen (TN) removal. In addition, a DO of 0.5 mg/L resulted in the best total nitrogen removal. A higher DO induces NOB activity and consequent lower TN removal efficiency. The optimal density of AO B and NO B density was 1~10% for a 10% ANAMMOX bacterial in the double-layered PVA/alginate gel beads. The real effects of operating parameters of the thickness of the outer layer, DO and concentrations of biomass balance should be intensively investigated in the controlled experiments in batch and continuous modes.

• 한국통신학회논문지
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• 제37C권11호
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• pp.1054-1063
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• 2012

본 논문에서는 다계층 브로드캐스트 통신 환경에서 주목받는 비균등 오류정정기법(UEP)에 대하여 기본 이론을 설명하고 그 효과와 응용 분야를 소개한다. 또한 현재까지의 UEP 기술의 연구 동향을 표준 적용 현황과 관련 논문의 소개를 통해 조명하고, 이를 통해 표준화 전망을 비롯한 앞으로의 활용 방안을 제시한다.

• 한국시뮬레이션학회논문지
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• 제24권3호
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• pp.77-87
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• 2015

국방 M&S(Modeling & Simulation) 분야는 컴퓨터상에 모의 전장 환경 및 무기 모델을 구축하고 다양한 시나리오에 의해 시뮬레이션을 수행하여 무기체계의 효과도를 분석하는 현실적인 수단으로 이용되고 있다. 그러나, 무기체계의 구조 및 행위가 복잡해짐에 따라 이를 시뮬레이션 모델로 만드는 과정이 어려워지고 있다. 모델 재사용 저장소는 시뮬레이션 모델 구축에 필요한 비용을 절감하기 위해 기존에 개발 및 검증된 모델을 저장하고 있다. 그러나 기존의 재사용 저장소들은 특정 플랫폼 및 환경에서만 운용되어 사용자 층에 제한이 있으며, 보안 및 무중단 서비스를 위한 메커니즘이 미흡하여 무기체계 모델과 같은 보안 및 신뢰성이 필요한 모델을 저장하기에는 한계가 있다. 본 논문에서는 무기체계 모델의 재사용을 장려하기 위한 클라우드 저장소인 W-Cloud (Weapon Cloud)를 구축하여 다양한 플랫폼 및 환경에서 활용될 수 있도록 하였다. 또한, 계층형 정보보호 및 기밀성 보장을 통해 무기 모델의 재사용 과정에서 생길 수 있는 보안상의 문제를 효과적으로 해결할 수 있도록 하였다.