• International Journal of Contents
• /
• 제12권1호
• /
• pp.70-75
• /
• 2016

In this paper, we considered heterogeneous spectrum sharing system where the number of subcarriers of the primary user (PU) was twice as much as that of the secondary user (SU). In this case, due to non-orthogonality and inter-carrier interference (ICI) from SU to PU, it is difficult to satisfy the interference constraint of PU. In order to mitigate ICI and satisfy the interference constraint, we proposed a new transmission scheme of the SU with power allocation scheme. The proposed scheme will only generate subcarrier-by-subcarrier interference. Therefore, it can easily satisfy the interference constraint of the PR and enhance the capacity of the SU. In addition, we derived the ergodic capacity of the SU. Based on numerical results, we confirmed that the proposed schemes could guarantee SU with a reliable capacity while satisfying the interference constraint of the PU. In addition, the derived capacity well matched the numerical results.

• 대한의용생체공학회:학술대회논문집
• /
• 대한의용생체공학회 1990년도 추계학술대회
• /
• pp.61-63
• /
• 1990

To develop better blood compatibility of commercial polyurethane(PU), PU surface was chemically modified wi th a hydrophobic perfluorocarhon or a hydrophilic polyethylene oxide(PEO) and/or sulfonated groups, respectively. The water contact angle of modified PUs varied from $110^{\circ}$ to $0^{\circ}$. All the modified PUs were more blood compatible than untreated PU. In particular, PEO-sulfonate grafted PUs showed a very enhanced antithrombogenicity due to the synergistic effect of PEO and $SO_3$ groups. Therefore more hydrophobic and hydrophilic PU surfaces are promising for improving the blood compatibility.

• 한국콘텐츠학회:학술대회논문집
• /
• 한국콘텐츠학회 2009년도 춘계 종합학술대회 논문집
• /
• pp.663-667
• /
• 2009

본 논문에서는 인접블록간의 움직임 유사도를 이용하여 불필요한 후보블록을 보다 빠르게 제거하는 PDE기반의 고속 블록매칭 알고리즘을 제안한다. 제안한 방법은 기존의 방법보다 불필요한 계수를 효율적으로 제거하기 위하여 인접 블록간의 영상의 유사성에 기초하여 인접한 네개의 매크로블록 가운데 최대 복잡도를 가지는 서브블록의 누적된 비율(cumulative distribution function-CDF)을 사용하고 서브블록별 복잡도가 집중되지 않도록 하기위하여 normalized 기반 매칭스캔 방법을 사용하여 효율적으로 계산량을 줄였다. 제안한 알고리즘은 화질의 저하 없이 기존의 PDE 알고리즘에 비해 60% 이상의 계산량을 줄였으며, MPEG-2 및 MPEG-4 AVC를 이용하는 비디오 압축 응용분야에 유용하게 사용될 수 있을 것이다.

• 한국정보처리학회:학술대회논문집
• /
• 한국정보처리학회 2003년도 춘계학술발표논문집 (중)
• /
• pp.807-810
• /
• 2003

EMFG(Extended Mark Flow Graph)는 이산시스템을 개념설계하거나 상세설계할 수 있는 좋은 도구이다. 시스템을 설계함에 있어서 마크흐름을 분석하는 것은 시스템의 성능향상과 직결되므로 상당히 중요한 작업이다. 본 논문에서는 EMFG의 각 박스들간의 상태변화를 박스추이가중행렬을 통하여 확인, 분석하는 기법을 제안하고자 한다. EMFG로 설계한 시스템의 상태변화를 쉽게 분석함으로써 시스템의 설계 및 분석이 쉬워지므로 자동화된 시스템 개발시 유용하게 사용될 것으로 기대된다.

• 폴리머
• /
• 제25권3호
• /
• pp.391-398
• /
• 2001

난연성분인 트리브로모아세트산의 함량을 10, 20, 30wt%로 변화시키면서 1,4-부탄디올, 아디프산 및 트리메틸올프로판과 축합중합을 하여 트리브로모 변성폴리에스테르(TBAO)를 합성한 후에, TBAO류와 이소시아네이트를 블렌드하여 2성분계 폴리우레탄(PU) 난연도료를 제조하였다. 제조된 난연도료의 도막물성을 측정한 결과, 결코 비난연도료보다 물성이 저하되지는 않았다. 또한 난연도료의 난연성 시험결과, 수직법에서 트리브로모아세트산 20 wt%에서 불꽃에 타지 않아서 양호한 난연도료임을 알 수 있었다.

• 한국공작기계학회논문집
• /
• 제16권5호
• /
• pp.55-62
• /
• 2007

With the developments in knitting, manufacturing, and polymers, coated gloves have been evolved in a way to maximize occupational safety and functionality. In this paper, we have considered the PU-coating process for the glove knitted by Dyneema to reduce the occurrence of the defects due to air bubble. This paper classifies the types of defect due to air bubble and traces their forming mechanisms. The air between coating layer of glove and mold's surface forms the defects if it is not evacuated fully in the process of submerging into water. The defects can be suppressed or avoided by forming air-evacuating path on the surface of the molds.

• 한국염색가공학회지
• /
• 제7권3호
• /
• pp.15-21
• /
• 1995

Polyurethane microcapsules containing dibutylphthalate(DBP) were perpared by the interfacial polymerization using diisocyanates and polyois. Effects of chemical structure of PU, dispersing agent and polymerization time on the mean diameter of microcapsules were investigated. The releasing of DBP from microcapsules depended on the chemical structure of PU and solvents. The diameter decreased with increasing dispersing agent concentration, and it is decreased in the order of the dispersing agents using gelatine > PVA > arabic gum at the same concentration. A slight increase in the diameter was observed when the ratio C$H_2$/OOCNH of PU was increased. As the ratio C$H_2$/OOCNH of PU was increased, the amount of extracted DBP for hexane using as a extracting solvent was decreased, however, it was not changed for THF.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2009년도 추계학술대회 논문집
• /
• pp.427-428
• /
• 2009

In the manufacture process of refrigerator cabinet, polyurethane(PU) liquid firstly is injected between outer plate and inner case in high temperature about $40^{\circ}C$, and PU foam is generated and solidified to the room temperature. There will be great residual stress in the PU foam, especially at the corners after the whole refrigerator is completely assembled. The stress condition will become more complicated under operating condition because of the large temperature difference between the freezing room and outer plate. And also, there are great differences of properties for plastic and steel which would cause different deformation under temperature gradient. The steel outer plate would expand compared to the PU foam or ABS material under operation condition, which induces a thermally bowing deformation in the refrigerator cabinet. The objective of this paper is to design an optimum bead structure or to use reinforcement in the refrigerator except for improving material properties in order to decrease the deformation.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2008년도 제39회 하계학술대회
• /
• pp.1755-1756
• /
• 2008

본 연구는 이동하면서 트롤리선 가설하는 작업로봇에서 가선 트롤리선에 대한 장력제어 방법이 제안되었다. 비선형 와이어 모델, AC 전동기를 이용한 장력발생 시스템 및 와이어 장력 방정식 에 기초하여 장력제어 시스템이 로드셀에 의한 장력 검출로 설계되고 실행되었다. 장력응답은 실험에서 만족하게 장력의 조절하는 것으로 보인다. 제안한 장력제어 시스템은 시뮬레이션과 실험을 통하여 그 결과가 유효함을 증명하였다.

• 한국염색가공학회지
• /
• 제22권3호
• /
• pp.246-256
• /
• 2010

This study studies on the physical property of MWNT/PU composite film for electrostatic dissipation (ESD) function by dispersing multi-wall carbon nanotubes (MWNT) in dimethylformamide (DMF) and by combining it with polyurethane(PU). For this purpose, four kinds of MWNT were selected and the composite films were made by dispersion processing, and their physical properties were measured and investigated in terms of electrical conductivity. For dispersion parameters, four MWNT contents(0.5, 1, 2, 5wt%) and two dispersion times(30min, 120min) were selected. The dispersion property and the electrical conductivity of MWNT/PU film was measured using a UV-Vis spectrometer and conductivity measuring apparatus. Finally, their physical properties according to the dispersion conditions were analyzed and discussed with various processing conditions.