• 폴리머
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• 제37권2호
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• pp.184-195
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• 2013

아크릴 점착테이프는 자동차, 전기전자 및 디스플레이 모듈 접합에 사용된다. 본 연구는 이러한 모듈 접합에 사용되는 고강도 준구조형 점착테이프 제조를 위해 2-ethylhexylacrylate(2-EHA)와 acrylic acid(AAC)를 사용하여 UV 조사에 의한 광중합 및 점착테이프 제조를 위해 광경화를 진행하였고, AAC의 함량 및 무기물 충전제 $SiO_2$ 함량에 따라 아크릴 점착테이프의 물성에 미치는 영향을 고찰하였다. 공단량체로 사용된 AAC의 함량이 많을수록 아크릴고분자 사슬의 강직성이 증가하여 초기 점착력이 낮았고, 시간경과에 따라 점착력이 증가하였으며 테이프의 젖음성, 접촉각 및 SEM 이미지를 통해 확인할 수 있었다. 충전제를 첨가하지 않은 점착테이프의 박리강도와 전단접착강도는 반비례 관계였으나 충전제를 첨가하면 함량 증가에 따라 박리강도 증가와 함께 전단접착강도가 증가하는 비례관계를 보였다. 이러한 상관관계로부터 고강도 준구조형 접착물성을 필요로 하는 용도에 최적화된 아크릴 점착테이프를 제시할 수 있었다.

• 방송공학회논문지
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• 제24권4호
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• pp.660-669
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• 2019

최근 3차원 스캐닝 장비 및 다차원 어레이 카메라의 발달로 AR(Augmented Reality)/VR(Virtual Reality), 자율 주행과 같은 응용분야에서 3차원 데이터를 다루는 기술에 관한 연구가 지속해서 이루어지고 있다. 특히, AR/VR 분야에서는 3차원 영상을 포인트 데이터로 표현하는 콘텐츠가 등장하였으나, 이는 기존의 2차원 영상보다 많은 양의 데이터가 필요하다. 따라서 3차원 포인트 클라우드 콘텐츠를 사용자에게 서비스하기 위해서는 고효율의 부호화/복호화와 저장 및 전송과 같은 다양한 기술 개발이 요구된다. 본 논문에서는 MPEG-I(MPEG-Immersive) V-PCC(Video based Point Cloud Compression) 그룹에서 제안한 V-PCC 부호화기를 통해 생성된 V-PCC 비트스트림을 MPEG-DASH(Dynamic Adaptive Streaming over HTTP) 표준에서 정의한 세그먼트로 구성하는 방안을 제안한다. 또한, 사용자에게 3차원 좌표계 정보를 제공하기 위해 시그널링 메시지에 깊이 정보 파라미터를 추가로 정의한다. 그리고 본 논문에서 제안된 기술을 검증하기 위한 검증 플랫폼을 설계하고, 제안한 기술의 알고리듬 측면에서 확인한다.

• 방송공학회논문지
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• 제24권2호
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• pp.329-340
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• 2019

최근 국내 지상파 UHD(Ultra-High Definition) 방송과 같은 고품질 AV(Audio-Video) 서비스가 증가하면서 그에 맞춰 방송 기술도 진화하게 되면서 방송 표준 또한 새롭게 정의하게 되었다. 또한, 네트워크 기술이 발달함에 따라, 콘텐츠가 해당 나라뿐 아니라 세계적으로 소비되고 있다. 그에 맞춰 국가 및 지역적 환경 등에 맞춰 적합한 콘텐츠를 제공하는 방안인 콘텐츠 삽입 기술이 필요할 것으로 보인다. 본 논문은 지상파 UHD 방송의 전송 표준 DASH(Dynamic Adaptive Streaming over HTTP)/ROUTE(Real time Object delivery Over Unidirectional Transport) 및 MMT(MPEG Media Transport)를 기반으로 방송망과 통신망의 이종 망 환경 하에 ATSC (Advanced Television Systems Committee) 3.0 Event Signaling 표준을 활용한 콘텐츠 삽입 서비스 시스템 모델 및 동기화 방안을 제안한다. 또한, 해당 서비스가 방송 표준을 만족하는 환경에서 동작함을 검증한다.

• 한국통신학회논문지
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• 제40권9호
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• pp.1776-1785
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• 2015

인터넷을 이용하는 사용자의 관점이 호스트 중심에서 콘텐트 중심으로 변화하면서 콘텐트 중심 네트워크 (Content Centric Network, 이하 CCN)라는 새로운 패러다임이 소개되었다. 한편, 최근 비디오 스트리밍에 대한 수요가 급증하고 있으며 더 높은 사용자의 만족도를 위한 적응형 스트리밍이 소개되면서 많은 연구가 진행 중에 있다. 따라서 CCN에서도 사용자의 수요에 따라 적응형 스트리밍을 고려할 필요성이 있다. 하지만 CCN에서 기존의 네트워크 구조에서와 동일한 방식으로 적응형 비디오 스트리밍 서비스를 할 경우 CCN 라우터 내 캐시를 (CS) 충분히 활용하지 못한다는 한계점이 있으며 또한 단말의 달라지는 요구 사항을 캐시 활용에 반영할 수 없는 문제점도 있다. 따라서 본 논문에서는 정규표현식을 활용한 콘텐트 네이밍 방식을 적용하여 기존 적응형 스트리밍 비트레이트 선택 알고리즘의 캐시활용도를 높이면서도 CCN의 기본 프로토콜에 적합한 프레임워크를 제시하고, 단말의 상태에 따라 동적인 표현식 기술 전략 및 선택 알고리즘을 통하여 비디오 스트리밍 품질을 개선하고자 한다.

• 한국재료학회지
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• 제33권10호
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• pp.393-399
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• 2023

In this study, changes in the microstructure and mechanical properties of cast and extruded Al-2Li-1Ce alloy materials were investigated as the Mg content was varied. The density decreased to 2.485, 2.46 and 2.435 g/cm³ when the Mg content in the Al-2Li-1Ce alloy was increased to 2, 4 and 6 wt%, respectively. Intermetallic compounds of Al₁₁Ce₃ were observed in all alloys, while the β-phase of Al₃Mg₂ was observed in alloys containing 6 wt% of Mg. In the extruded material, with increasing Mg content the average grain size decreased to 84.8, 71.6 and 36.2 ㎛, and the fraction of high-angle grain boundaries (greater than 15°) increased to 82.8 %, 88.6 %, and 91.8 %, respectively. This occurred because the increased Mg content promotes dynamic recrystallization during hot extrusion. Tensile test results showed that as the Mg content increased, both the yield strength and tensile strength increased. The yield strength reached 86.1, 107.3, and 186.4 MPa, and the tensile strength reached 215.2, 285, and 360.5 MPa, respectively. However, it is worth noting that the ductility decreased to 27.78 %, 25.65 %, and 20.72 % as the Mg content increased. This reduction in ductility is attributed to the strengthening effect resulting from the increased amount of dissolved Mg, and grain refinement due to dynamic recrystallization.

• Carbon letters
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• 제22권
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• pp.36-41
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• 2017

Biodegradable epoxy (B-epoxy) was prepared from diglycidyl ether of bisphenol A and epoxidized linseed oil. The mechanical properties of B-epoxy composites reinforced with multi-walled carbon nanotubes (MWCNTs/B-epoxy) were examined by employing dynamic mechanical analysis, critical stress intensity factor ($K_{IC}$) tests, and impact strength tests. The electromagnetic interference shielding effectiveness (EMI-SE) of the composites was evaluated using reflection and absorption methods. Mechanical properties of MWCNTs/B-epoxy were enhanced with an increase in the MWCNT content, whereas they deteriorated when the MWCNT content was >5 parts per hundred resin (phr). This can likely be attributed to the entanglement of MWCNTs with each other in the B-epoxy due to the presence of an excess amount of MWCNTs. The highest EMI-SE obtained was ~16 dB for the MWCNTs/B-epoxy composites with a MWCNT content of 13 phr at 1.4 GHz. The composites (13 phr) exhibited the minimum EMI-SE (90%) when used as shielding materials at 1.4 GHz. The EMI-SE of the MWCNTs/B-epoxy also increased with an increase in the MWCNT content, which is a key factor affecting the EMI-SE.

• Journal of Multimedia Information System
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• 제4권3호
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• pp.123-144
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• 2017

Personalized media includes user-targeted and user-generated content (UGC) exchanged through social media and interactive applications. The increased consumption of UGC presents challenges and opportunities to multimedia information systems. We work towards modeling a deep structure for content networks. To gain insights, a hybrid practice with Media Framework (MF) is presented for network creation of personalized media, which leverages the authoring methodology with user-generated semantics. The system's vertical integration allows users to audition their personalized media networks in the context of a global system network. A navigation scheme with dynamic GUI shifts the interaction paradigm for content query and sharing. MF adopts a multimodal architecture anticipating emerging use cases and genres. To model diversification of platforms, information processing is robust across multiple technology configurations. Physical and virtual networks are integrated with distributed services and transactions, IoT, and semantic networks representing media content. MF applies spatiotemporal and semantic signal processing to differentiate action responsiveness and information responsiveness. The extension of multimedia information processing into authoring enables generating interactive and impermanent media on computationally enabled devices. The outcome of this integrated approach with presented methodologies demonstrates a paradigmatic shift of the concept of UGC as personalized media network, which is dynamical and evolvable.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2006년도 춘계 학술발표회 논문집
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• pp.607-616
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• 2006

More strict construction control of railway roadbeds is demanded in high speed railway system because of heavier repeated dynamic loading than conventional railways. The aim of this study is to propose a compaction control methodology of crushed-rock-soil-fills including as large particles as $200\sim300mm$ in diameter, which are easily encountered in high speed railway roadbed. Field tensity evaluation and in turn compaction control of such crushed-rock-soil-fills are almost impossible by conventional methods such as in-situ density measurements or plate loading tests. The proposed method consists of shear wave measurements of compaction specimens in laboratory and in-situ measurements of fills. In other words, compaction control can be carried out by comparing laboratory and field shear wave velocities using as a compaction control parameter. The proposed method was implemented at a soil site in the beginning and will be expanded to crushed-rock-soil-fills in future. One interesting result is that similar relationship of shear wave velocity and water content was obtained as that of density and water content with the maximum value at the optimum moisture content.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제9권8호
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• pp.3121-3135
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• 2015

Owing to the increase in consumption of multimedia content and the improvement of device capacity, user demand for high-quality content has increased. However, it is difficult to transport such large amounts of content over the existing broadcasting network with limited bandwidth. To provide high-definition broadcasting, some studies suggest methods of transporting multimedia over heterogeneous networks after encoding content hierarchically. MPEG Media Transport (MMT), standardized by Moving Picture Experts Group (MPEG), is a solution that enables large-volume media transport over heterogeneous networks such as digital broadcasting networks and packet-switched networks. In the case of delivering a scalable encoded video over different networks, synchronization of each stream is an important issue. MMT defines a synchronization scheme, but does not contain sufficient functions to implement it. In this paper, we propose a synchronization scheme for media streams that are encoded hierarchically, divided into layers, and transported over heterogeneous networks. We implement our scheme using MMT and HTTP, and experimented using three encapsulated video streams with different durations. As a result, we show that the proposed scheme can reduce the waiting time to display high-quality video, relative to Dynamic Adaptive Streaming over HTTP-Scalable Video Coding (DASH-SVC) by requesting segments of enhanced layers after calculating the transmission time. Additionally, we find out that the selection of durations have a relation to the characteristics of the video.

• Macromolecular Research
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• 제11권6호
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• pp.410-417
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• 2003

Poly(methyl methacrylate-co-acrylonitrile) [P(MMA-co-AN)]/Na-MMT nanocomposites were synthesized through emulsion polymerization with pristine Na-MMT. The nanocomposites were exfoliated up to 20 wt% content of pristine Na-MMT relative to the amount of MMA and AN, and exhibited enhanced storage moduli, E', relative to the neat copolymer. The exfoliated morphology of the nanocomposite was confirmed by XRD and TEM. 2-Acryla-mido-2-methyl-1-propane sulfonic acid (AMPS) widened the galleries between the clay layers before polymerization and facilitated the comonomers, penetration into the clay to create the exfoliated nanocomposites. The onset of the thermal decomposition of the nanocomposites shifted to a higher temperature as the clay content increased. By calculating areas of tan$\delta$ of the nanocomposites, we observed that the nanocomposites show more solid-like behavior as the clay content increases. The dynamic storage modulus and complex viscosity increased with clay content. The complex viscosity showed shear-thinning behavior as the clay content increased. The Young's moduli of the nano-composites are higher than that of the neat copolymer and they increase steadily as the silicate content increases, as a result of the exfoliated structure at high clay content.