• 제목/요약/키워드: Intensity transformation

검색결과 172건 처리시간 0.028초

연성된 쉘 구조물의 진동 파워흐름해석 (Vibration Power Flow Analysis of Coupled Shell Structures)

  • 김일환;홍석윤;박도현;길현권
    • 한국소음진동공학회:학술대회논문집
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    • 한국소음진동공학회 2002년도 추계학술대회논문집
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    • pp.492-497
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    • 2002
  • In this paper, Power Flow Analysis(PFA) method has been applied to the prediction of vibration energy density and intensity of coupled shell structures in the medium-to-high frequency ranges. To consider the wave transformation at joint between shell elements, power transmission and reflection coefficients are investigated for various joint angles, and here Donnell-Mushtari thin shell theory has been used. For validations computations are performed to analyze the response of coupled shells by changing the excitation frequency and damping loss factor.

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4밸브기관의 압축상사점 부근의 난류특성에 관한 수치해석적 연구 (A Numerical Study on the Turbulent Flow Characteristics Near Compression TDC is Four-Valve-Per-Cylinder Engine)

  • 김철수;최영돈
    • 한국자동차공학회논문집
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    • 제1권1호
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    • pp.1-13
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    • 1993
  • The three-dimensional numerical analysis for in-cylinder flow of four-valve engine without intake port has been successfully computed. These computations have been performed using technique of the general coordinate transformation based on the finite-volume method and body-fitted non-orthogenal grids using staggered control volume and covariant variable as dependent one. Computations are started at intake valve opening and are carried through top-dead-center of compression. A k-$\varepsilon$model is used to represent turbulent transport of momentum. The principal study is the evolution of interaction between mean flow and turbulence and of the role of swirl and tumble in generating near TDC turbulence. Results for three different inlet flow configuration are presented. From these results, complex flow pattern may be effective for promoting combustion in spark-ignition engines and kinetic energy of mean flow near TDC is well converted into turbulent kinetic energy.

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X선회절법(線回折法)에 의한 천연 셀룰로오스 섬유의 알칼리 팽윤구조(膨潤構造) (Alkali-Swollen Structures of Native Cellulose Fibers by X-ray Diffraction Methods)

  • 김남훈
    • Journal of the Korean Wood Science and Technology
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    • 제20권1호
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    • pp.38-45
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    • 1992
  • Fine and alkali-swollen structures of native cellulose fibers were investigated by x-ray diffraction methods. The results of fine structures are shown in Table 1. In meridional x-ray diffractograms, the relative intensity ratio R of (002) to (004) for cellulose I was ca. 0.05 and for regenerated cellulose it was ca. 0.45. It was considered that the transformation from cellulose I to cellulose II resulted from the packing or conformational change of cellulose chain. Finally. although cellulose I was not detected in the alkali-swollen celluloses treated for 1 hr to 24 hrs, washing and drying them resulted in the generation of considerable amounts of cellulose I and the amount decreased with increasing alkali duration.

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플라즈마 용사된 부분안정화 지르코니아 코팅의 상온 마모거동에 미치는 열처리온도 및 분위기의 영향 (The Effects of the Annealing Temperature and Environments on Room Temperature Wear Behavior of Plasma-Sprayed Partially Stabilized Zirconia Coatings)

  • 김장엽;임대순
    • 한국세라믹학회지
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    • 제31권10호
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    • pp.1176-1180
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    • 1994
  • The sliding wear behavior of the plasma-sprayed zirconia containing 3 mol% yttria was investigated after the annealing at room temperature to 80$0^{\circ}C$ in various concentrations of humid atmosphere as laboratory, humid, dry argon atmosphere. Both of the friction coefficient and the wear loss increased with increasing temperature up to 80$0^{\circ}C$. Surface morphology of the worn samples changed with annealing temperature. The change of monoclinic/tetragonal (m/t) x-ray peak intensity ratio effected the wear behavior. The m/t ratio had maximum value at 20$0^{\circ}C$ and decreased with increased temperature in laboratory and humid atmosphere. In argon atmosphere the m/t ratio had no maximum value and decreased with increasing temperature. At all the annealing temperature humid atmosphere had more the m/t ratio value than any other atmosphere. The change of toughness was showed the inversed result of m/t ratio change. The results indicated that the resudial stress which was induced by the different amount of phase transformation takes a detrimental role in wear behavior.

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지르코니아 겔에서 열처리에 따른 광발광의 변화 (Variation of Photoluminescence in Zirconia Gel by Pyrolysis)

  • 한규석;고태경
    • 한국세라믹학회지
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    • 제45권2호
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    • pp.126-131
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    • 2008
  • In this study, we prepared zirconia gel by the sol-gel method and investigated its photoluminescence properties by varying pyrolysis temperature. The addition of acetic acid into a Zr-alkoxide solution resulted in forming the bidentate ligands with Zr ions and producing a stable gel. At the pyrolysis temperature of $350^{\circ}C$, the zirconia nanocrystals with tetragonal structure gradually appeared in the gel. The PL intensity of the zirconia gel increased with increasing the pyrolysis temperature up to $350^{\circ}C$, but decreased above the temperature. Concurrently, its PL peak wavelength continuously shifted from ${\sim}440\;nm$ to ${\sim}550\;nm$ with the temperature. The PL characteristics of the zirconia gels were closely associated with decomposition of residual organic groups, the formation of the zirconia nanocrystals, and the tetragonal to monoclinic phase transformation.

표면 연마가 3Y-TZP의 저온열화에 미치는 영향 (Effect of Surface Grinding on Low Temperature Degradation of 3Y-TZP)

  • 김대준;이홍림;정형진
    • 한국세라믹학회지
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    • 제30권2호
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    • pp.164-168
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    • 1993
  • Grinding of 3mol% Y-TZP enhanced the texturing of t-ZrO2, which is represented by the increased I(002)t/I(200)t peak intensity ratio, and an asymetric broadening of (111)t peak. The degree of texturing and asymetric broadening depended on a seversity of grinding. The asymetric (111)t peak broadening was resulted by the formation of r-ZrO2. When aged at 25$0^{\circ}C$ for 120h, r-ZrO2 transformed to t-ZrO2 due to the relief of stressed surface area and the amount of tlongrightarrowm transformation inversely varied with the I(002)t/I(200)t. The inverse dependence was interpreted by that the degree of texturing determines the magnitude of residual surface stress and the lattice relaxation of t-ZrO2, which causes the low temperature degradation, is retarded as the residual stress becomes greater.

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시각 시스템 모델을 이용한 Subband 코딩 (On Using the Human Visual System Model for Subband Coding)

  • 박용철;김근숙;차일환;윤대희
    • 대한전자공학회논문지
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    • 제27권6호
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    • pp.937-943
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    • 1990
  • In this paper, a subband coding scheme using the human visual system(HVS) model for encoding monochrome images is proposed to produce perceptually higher quality images compared with the regular subband coding scheme. The proposed approach first transforms the intensity image to the density image by a point nonlinear transformation. A frequency band dexomposition of the density image is carried out by means of 2-D seaprable quadrature mirror filters, which split the density image spectrum into 16 equall rate subbands. Bits are allocated among the subbands to minimize the weighted mean squar error (WMSE) for differential pulse code modulation(DPCM) coding of the subbands. The weight for each subband is calculated from the modulation transfer function (MTF) of the HVS model at corresponding frequencies. The performances of the proposed approach are evaluated for 256 * 256 monochrome images at the bit rates of 0.5, 0.75 and 1.0 bita per pixel. Computer simulation results indicate that using the HVS model yields more pleasing reconstructed images than regular subband coding approach which does not use HVS model.

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고려인삼 광계 II Chlorophyll a/b binding Protein 유전자(CAB)의 cloning 및 식물에의 활용연구 (Cloning of CAB cDNA encoding chlorophyll a/b binding protein of photosystem II in Korean ginseng and Use in Plant)

  • 김갑식;이기원;이종철;여운형;채순용;박은경
    • 한국연초학회지
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    • 제21권2호
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    • pp.152-159
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    • 1999
  • A CAB cDNA clone(pKGCAB) encoding the light harvesting chlorophyll a/b binding protein of the semi-shade plant, Korean ginseng(Panax ginseng C. A. Meyer) was isolated by the one-way path random sequencing of ginseng cDNA library clones and transgenic tobacco plants(Nicotiana tabacum NC82) were produced by the transformation of this ginseng CAB gene in use of Agrobacterium tumefaciens LBA4404. The CAB gene showed type 1 structure of LHCP-II, 84% similarity in nucleotide sequence and 92% in amino acid sequence to that of Nicotiana tabacum CAB40, respectively. Seed germination and initial growth of the transgenic tobacco plants transformed with the cDNA fragment were accelerated under low light intensity compared with those of normal tobacco plant, that may result from the higher light sensitivity of the transgenic plants than that of the normal.

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Effect of Batch Melting Temperature and Raw Material on Iron Redox State in Sodium Silicate Glasses

  • Mirhadi, Bahman;Mehdikhani, Behzad
    • 한국세라믹학회지
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    • 제48권2호
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    • pp.117-120
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    • 2011
  • In this study, the redox state of iron in sodium silicate glasses was varied by changing the melting conditions, such as the melting temperature and particle size of iron oxide. The oxidation states of the iron ion were determined by wet chemical analysis and UV-Vis spectroscopy methods. Iron commonly exists as an equilibrium mixture of ferrous ions, $Fe^{2+}$, and ferric ions $Fe^{3+}$. In this study, sodium silicate glasses containing nanoparticles of iron oxide (0.5% mol) were prepared at various temperatures. Increase of temperature led to the transformation of ferric ions to ferrous ions, and the intensity of the ferrous peak in 1050 nm increased. Nanoparticle iron oxide caused fewer ferrous ions to be formed and the $\frac{Fe^{2+}}{Fe^{3+}}$ equilibrium ratio compared to that with micro-oxide iron powder was lower.

Retroreflection 시스템의 다체형 회전체의 변환모형에 관한 연구 (A Conversion Model of the Various Rotational Body Shapes in the Retroreflection System)

  • 박범
    • 한국안전학회지
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    • 제10권4호
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    • pp.109-117
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    • 1995
  • 본 논문은 야간 운전자들의 안전을 위한 교통안전제어 시설체계인 주행안내 반사체시스템(Retroreflector)에 있어서 기하도형각과 명확도 사이에 성량 변형이 등가적인 새로운 이론적 설계에 의한 다체형 회전체의 전환 모형에 관한 연구이다. 야간운전자의 주행안내 반사체 성능과 운전자 환경을 고려하여 이론적으로 동질적인 다섯가지 모형을 검증한다. 이 모형은 주행안내 반사체 교통체계를 설계하는데 좀더 나은 운전성과, 안전, 그리고 경제성 등을 고려하여 평가할 수 있을 것이다.

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