• Title/Summary/Keyword: cell radius

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Investigation on the characteristics of a cavity-dumped Nd:glass laser (Cavity-dumping형 Nd:glass laser의 제작 및 특성 조사)

  • 차용호;강응철;남창희
    • Korean Journal of Optics and Photonics
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    • v.6 no.2
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    • pp.130-134
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    • 1995
  • A small signal gain coefficient of Nd:glass was measured and a cavity-dumped laser was constructed. To measure the small signal gain coefficient, we constructed a resonator consisting of Nd:glass, Pockels cell, polarizing beam splitter. The measured small signal gain coefficient was $0.088 cm_{-1}$ when the input energy was 100 J and the round-trip internal loss of the resonator was 56%. The cavity-dumped laser was constructed using Nd:glass. 2 m radius of curvature HR-mirrors, Pockels cell, polarizinig beam splitter and $\lambda/4$ plate. The output energy of cavity-dumped laser was 0.85 J at 140 J input energy and the laser pulse width was 8 ns.s 8 ns.

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Charge/discharge Properties of $Li_xV_3O_8$ Composite Cathode for Lithium Polymer Batteries (리튬 폴리머 전지용 $Li_xV_3O_8$ Composite Cathode의 충방전 특성)

  • Park, B.G.;Kim, J.U.;Park, G.C.;Gu, H.B.
    • Proceedings of the KIEE Conference
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    • 1997.07d
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    • pp.1591-1593
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    • 1997
  • The purpose of this study is to research and develop $Li_xV_3O_8$ composite cathode for lithium polymer battery. We investigated electrochemical, interfacial properties and charge/discharge cycling of $Li_xV_3O_8$/SPE/Li cell. The radius of semicircle associated with the interfacial resistance of $Li_xV_3O_8$/SPE/Li cell increased very slowly during discharge process from 100% SOC to 90% SOC. And then the cell resistance was increased at discharge process from 10% SOC to 0% SOC. The discharge capacity based on $Li_xV_3O_8$ was 212mAh/g at 15th cycle. The $Li_xV_3O_8$/SPE/Li cell has a good properties.

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Asymptotic Performance of MIMO-MC-CDMA Systems in Multi-cell Environments (다중셀 환경에서 MIMO-MC-CDMA시스템의 점근적 성능)

  • Kim, Kyeong-Yeon;Ham, Jae-Sang;Lee, Chung-Yong
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.44 no.7 s.361
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    • pp.47-52
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    • 2007
  • This paper analyzes the output signal-to-interference-plus-noise ratio (SINR) for a multiple-input-multiple-output (MIMO) multicarrier code division multiple access (MC-CDMA) system with minium mean square error receivers in multi-cell environments. A previous work in single cell environments is extended into analysis in multi-cell environments. The use of Haar unitary code matrix for asymptotic analysis causes other cell interferences expressed with a diagonal matrix haying different diagonal values. This paper shows that other cell interferences converge to an identity matrix whose gain is expressed by only other cell interference power in mean square sense and finds asymptotic deterministic SINRs for a given other cell interference. Under the assumption that the sum of lognormal fading components is distributed by other lognormal function, we show the comparison between theoretical performances and simulations from the view point of bit error rate and present average throughput performance according to the cell radius.

Forward Link Power Allocation and Capacity of IMT-2000 System (IMT-2000 시스템의 순방향 링크 전력할당과 용량유도)

  • Ro, Sang-Min;Kim, In-Kyoung;Kim, Joo-Eung;Daesik Hong;Kang, Chang-Eon;Jung, Hyun-Meen
    • Proceedings of the IEEK Conference
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    • 2000.11a
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    • pp.117-120
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    • 2000
  • This paper discusses solutions for forward link power allocation based on 3GPP(FDD) standardization reports and which meet the required Eb/No of forward link channels. In addition, the forward link user capacity in a mixed service environment. Cell coverage is induced from the user capacity solutions using the urban propagation model. In an urban macrocell environment, the forward link user capacity turns out to be roughly 29 and 3, respectively, for voice and data service (144 kbps) at a distance of 1 km, and in an urban microcell environment, the user capacity turns out to be Toughly 14, 4, and 2, respectively, for voice and two data services (144 kbps, 384 kbps) when the cell radius is 0.2 km.

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Generation of Microcellular Foams in Viscoelastic Polymer Solutions (점탄성 폴리머 용액에서의 초미세 폼의 생성)

  • Kang, Sung- Lin;Kim, Ki-Young;Kwak, Ho-Young
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.28 no.6
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    • pp.726-733
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    • 2004
  • The growth of the critical size bubble by diffusion process in viscoelastic medium was treated by an integral method for the concentration boundary layer adjacent to the bubble wall. In this study, we obtained a set of the first order time dependent equations to obtain bubble radius and gas pressure inside the bubble simultaneously. The calculated final cell sizes depending on the initial saturation pressure are in close agreement with the observed ones. The governing equations developed in this study may be used in polymer processing of microcellular foams.

The Effect of Blank Holding Force on Thickness Variation in Simultaneous Sheet forming process with Circle and Rectangle Shape of AZ31B Magnesium Sheet (AZ31B 마그네슘 판재의 원형 및 사각형 동시변형 공정에서 블랭크 홀딩력이 두께변화에 미치는 영향)

  • Kwon, K.T.;Kang, S.B.;Kim, H.H.;Kang, C.G.
    • Transactions of Materials Processing
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    • v.18 no.7
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    • pp.531-537
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    • 2009
  • The effect of blank holding force on thickness variation in simultaneous sheet forming with rectangular shape and circular has been demonstrated. Because has investigated an effect on formability of magnesium sheet, in this paper, the effect of punch radius on formability have been thinning, various crack phenomena and forming velocity. By simultaneously forming process with circular and rectangular shape, the data of simultaneously forming process with circular and rectangular shape will used to a part development such as notebook computer case, cell phone and bipolar plate of fuel cell.

A Study of Radio Wave Propagation Characteristics at 900MHz Range for Urban Modelling (도시형 모델링을 위한 900MHz대 전파전파 특성에 대한 연구(I))

  • 남채우;박성교박종백
    • Proceedings of the IEEK Conference
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    • 1998.06a
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    • pp.165-168
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    • 1998
  • This paper describes the characteristics of CT-2 radio wave propagation at 900MHz range. Typical cell coverage of CT-2 based on picocellular design provides a 200m radius. The five sites of urban regions of Kwang Ju city were chosen to characterize propagation in various environments. On the basis of cell coverage data measured with field strength meter, average 75% of telepoint service was retained and it was lack 25% of overall gain. In some sites telepoint service was limited to two of four directions around a station. If specially designed collinear antenna with specific directivities are used in these shadow area, improved results will be acquired.

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Charge/discharge Properties of $LiMn_2O_4$ Composite Cathode for All-solid state Rechargeable Batteris (리튬 고체전지용 $LiMn_2O_4$ Composite Cathode의 충방전 특성)

  • Kim, Jong-Uk;Park, Gye-Choon;Gu, Hal-Bon
    • Proceedings of the KIEE Conference
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    • 1998.07d
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    • pp.1511-1513
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    • 1998
  • The purpose of this study is to research and develop PEO/PVDF electrolytes and $LiMn_2O_4$ composite cathode for all-solid state lithium rechargeable battery. We investigated AC impedance response and charge/discharge cycling of $LiMn_2O_4$/SPE/Li cells. The cell resistance was decreased so much initial charge process from 0% SOC to 100% SOC. The radius of semicircle of $LiMn_2O_4$/SPE/Li cell was so much from initial state to 20th cycling. The discharge capacity of the $LiMn_2O_4$ composite cathode was 144mAh/g based on $LiMn_2O_4$.

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Characteristics of Rotating Stall in a Centrifugal Compressor with Vaned Diffuser (원심압축기 베인 디퓨저에서의 선회실속 특성)

  • Lee, Du-Yeol;Kang, Chang-Sik;Shin, You-Hwan;Kim, Kwang-Ho
    • The KSFM Journal of Fluid Machinery
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    • v.5 no.1 s.14
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    • pp.42-48
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    • 2002
  • In this study, the instability of a centrifugal compressor with vaned diffuser was investigated. During unstable operation of the test compressor, pressure fluctuations at different diffuser radius ratios were measured by using high frequency pressure transducers. Two different types of stall, mild and deep stalls, were observed alternately and irregularly at some flow rates where the compressor performance was steeply deteriorated. In this transient zone, the size of rotating stall cell was estimated through the wavelet transform analysis. It was about 45 percents of rotor circumferential space at 300 rpm and not dependent on flow rate.

Characteristics of Rotating Stall in a Centrifugal Compressor with Vaned Diffuser (원심압축기 베인 디퓨저에서의 선회실속 특성)

  • Lee, Du-Yeol;Kang, Chang-Sik;Shin, You-Hwan;Kim, Kwang-Ho
    • 유체기계공업학회:학술대회논문집
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    • 2001.11a
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    • pp.99-105
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    • 2001
  • In this study, the instability of a centrifugal compressor with vaned diffuser was investigated. During unstable operation of the test compressor, pressure fluctuations at different diffuser radius ratios were measured by using high frequency pressure transducers. Two different types of stall, mild and deep stall, were observed alternately and irregularly at some flow rate where the compressor performance was steeply deteriorated. In this transient zone, the size of rotating stall cell was estimated through the Wavelet transform analysis. It was about 45 percents of rotor circumferential space at 3000 rpm and not dependent on flow rate.

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