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A Expermental Study on the Dynamic Coefficients according to the Source Positions in Externally Pressurised Air-lubricated Journal Bearing with Two Row Sources (2열 외부가압 공기 저어널 베어링에서 공기 급기구 위치에 따른 동적계수에 관한 실험적 연구)

  • 이종렬;이준석;성승학;이득우
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • 2001.06a
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    • pp.231-235
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    • 2001
  • This paper has been presented the dynamic effect by the journal speed. eccentricity and source positions in order to overcome the defects of air bearing such as low stiffness and damping coefficient. Choosing the two row source position of air bearing is different from previous investigations in the side of pressure distribution of air film by the wedge effects. These optimal chooses of the two row source positions enable us to improve the performance of the film reaction force and loading force as making the high speed spindle. The results of investigated characteristics may be applied to precision devices like ultra-precision grinding machine and ultra high speed milling.

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2.2-inch QCIF+ a-Si TFT-LCD using Integrated Row Driver Circuits (Row Driver 회로가 집적된 2.2-inch QCIF+ a-Si TFT-LCD)

  • Yun, Y.J.;Han, S.W.;Jung, C.G.;Chung, K.H.;Kim, H.S.;Kim, S.Y.;Lim, Y.J.
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.18 no.3
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    • pp.264-268
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    • 2005
  • A 2.2-inch QCIF+(176${\times}$RGB${\times}$220) TFT-LCD with integrated row driver was developed using a standard amorphous silicon TFT technology. At low temperature, the integrated row driver operation is dramatically effected by the electron drift mobility reduction(■50 %) and the threshold voltage shift (■1V) of the a-Si TFT. We studied the dependency of circuit design and found that higher on-current circuit is important to guarantee good operation in wide temperature range.

Sloshing design load prediction of a membrane type LNG cargo containment system with two-row tank arrangement in offshore applications

  • Ryu, Min Cheol;Jung, Jun Hyung;Kim, Yong Soo;Kim, Yooil
    • International Journal of Naval Architecture and Ocean Engineering
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    • v.8 no.6
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    • pp.537-553
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    • 2016
  • This paper addresses the safety of two-row tank design by performing the extensive sloshing model tests. Owing to the uncertainties entangled with the scale law transforming the measured impact pressure up to the full scale one, so called comparative approach was taken to derive the design sloshing load. The target design vessel was chosen as 230 K LNG-FPSO with tow-row tank arrangement and the reference vessel as 138 K conventional LNG carrier, which has past track record without any significant failure due to sloshing loads. Starting with the site-specific metocean data, ship motion analysis was carried out with 3D diffraction-radiation program, then the obtained ship motion data was used as 6DOF tank excitation for subsequent sloshing model test and analysis. The statistical analysis was carried out with obtained peak data and the long-term sloshing load was determined out of it. It was concluded that the normalized sloshing impact pressure on 230 K LNG-FPSO with two-row tank arrangement is higher than that of convectional LNG carrier, hence requires the use of reinforced cargo containment system for the sake of failure-free operation without filling limitation.

2-2-inch QCIF+ a-Si TFT-LCD Using Integrated Row Driver Circuits (Row Driver 회로가 집적된 2.2-inch QCIF+ a-Si TFT-LCD)

  • Yun, Y.J;Han, S.W.;Jung, C.G.;Chung, K.H.;Kim, H.S.;Kim, S.Y.;Lim, Y.J.
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2004.11a
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    • pp.559-562
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    • 2004
  • A 2.2-inch QCIF+ $(176{\times}RGB{\times}220)$ TFT-LCD with integrated row driver was developed using a standard amorphous silicon TFT technology. At low temperature $({\sim}-20^{\circ}C)$, the integrated row driver operation is dramatically effected by the electron drift mobility variation $({\sim}50%)$ and the threshold voltage shift $({\sim}1V)$ of the a-Si TFT. We studied the temperature dependency of the circuit design and found that higher on-current circuit is important to guarantee good operation in wide temperature range.

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Experimental Study on the Heat Transfer under the Effects of Wake In a Turbine Cascade (후류의 영향을 고려한 터빈 캐스케이드내 열전달 현상에 대한 실험적 연구)

  • Min, H.K.;Chung, J.T.
    • Proceedings of the KSME Conference
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    • 2001.11b
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    • pp.36-41
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    • 2001
  • In order to simulate wake of stator and a gas turbine engine's balde row, acryl cylinder and a linear turbine cascade were used respectively in this study. Experimental of heat transfer distributions was done on the passage endwall and blade suction surface. Temperature distributions on the experimental regions were obtained through image processing system by using the cholesteric type liquid crystal which has chain structure of metyl$(CH_3)$. To represent the degree of heat transfer, dimensionless St number was used. The results show that heat transfer on the blade suction surface was increased due to the wake from the cylinder and was decreased as the distance between cylinder row and blade row increases. Because of groth of passage vortex, heat transfer distributions on the trailing edge area showed triangular shape which was little changed with wake. On the other hand, heat transfer on the passage endwall was decreased due to the wake from cylinder. As the distance between cylinder row and blade row increases, heat transfer was more decreased.

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Interaction of Di-Methylaluminum Groups with Hydroxyl Groups on a Fully Hydroxyl-Terminated Si (001) Surface

  • Kim, Dae-Hee;Kim, Dae-Hyun;Kim, Yeong-Cheol;Seo, Hwa-Il
    • Transactions on Electrical and Electronic Materials
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    • v.11 no.1
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    • pp.11-14
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    • 2010
  • The interaction of -$Al(CH_3)_2$ with -OH on a fully OH-terminated Si (001) surface was studied using density functional theory. Two sites for $Al(CH_3)_3$ to react with the -OH on the surface were identified. The $-Al(CH_3)_2$ product energetically favored the dimer-row site rather than the inter-row site because the Al atom of $-Al(CH_3)_2$ at the dimer-row site was attracted by the lone pair electrons of the O atom in the neighboring -OH. The energy barrier for the transfer of the $-Al(CH_3)_2$ between the two sites was 0.11 eV, and therefore, the $-Al(CH_3)_2$ at the inter-row site can easily transfer to the dimer-row site at room temperature.

Small Active Command Design for High Density DRAMs

  • Lee, Kwangho;Lee, Jongmin
    • Journal of the Korea Society of Computer and Information
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    • v.24 no.11
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    • pp.1-9
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    • 2019
  • In this paper, we propose a Small Active Command scheme which reduces the power consumption of the command bus to DRAM. To do this, we target the ACTIVE command, which consists of multiple packets, containing the row address that occupies the largest size among the addresses delivered to the DRAM. The proposed scheme identifies frequently referenced row addresses as Hot pages first, and delivers index numbers of small caches (tables) located in the memory controller and DRAM. I-ACTIVE and I-PRECHARGE commands using unused bits of existing DRAM commands are added for index number transfer and cache synchronization management. Experimental results show that the proposed method reduces the command bus power consumption by 20% and 8.1% on average in the close-page and open-page policies, respectively.

A thermal microwave emission model for row-structured vegetation (이방성 물질의 마이크로파대역 열 발산 모델)

  • Eom, Hyo J.
    • The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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    • v.3 no.2
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    • pp.40-45
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    • 1992
  • A simple emission model applicable for low scattering (scattering << absorption) anisotropic layer is developed and applied to the interpretation of measurements of microwave emission from row crops. The vegetation layer of row crops is modeled as a random slab embedded with small spheroid with major axis aligend paralel to the crop-row direction. The total emission is given in a simple algebraic form based on the zero-order radiative transfer theory. The single scattering albedo for spheroid and its polarimetric phase function are presented. The effects of layer azimuthal dependence on emission are accounted for by using an anisotropic albedo in the zero-order transfer theory. The developed emission theory favorably compares with the brightness temperature measured over soybeans canopy.

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Design Factors of Boom Sprayer(II) -Spray Droplet Size and Coverage Characteristics on Rice Plants- (붐방제기 살포장치의 설계요인 구명을 위한 실험적 연구(II) -노즐의 분무유형 및 벼의 피복특성-)

  • 정창주;김학진;이중용;최영수;최중섭
    • Journal of Biosystems Engineering
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    • v.20 no.4
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    • pp.313-322
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    • 1995
  • This study was conducted to find the design factors of spraying device of the boom sprayer for low volume application. Specific objectives of this study were 1) to select proper nozzles for broadcast spraying and row crop spraying by the nozzle spray characterisic experiment, and 2) to investigate the coverage characteristic of rice plant at the row crop spraying. The results of this study are summarized as follows. (1) From the tested results on the droplet diameter spectrum and spray pattern the standard flat-fan nozzle and drift guard nozzle were judged as appropriate for the broadcasting. Even flat-fan nozzle showed similar span values to standard flat-fan nozzles and drift guard nozzle : however, the nozzles were found to be inappropriate for broadcasting because of their spray pattern. Hollow cone nozzle showed relatively small span values and uniform spray pattern. (2) For the upper and lower sides of the rice plants, coverage rates of even flat-fan nozzles and hollow cone nozzles were maximum at the second row, but decreased rapidly after the third row. For the middle side of the rice plants, coverage rates of them were maximum at the first row, but decreased rapidly. When one nozzle was tested, C.V. values were in the range of 90~160% and 60~160% on entire heights of rice plant for even flat-fan nozzles and hollow cone nozzles respectively. C.V. values at other parts were poor. Spray coverage rate at the middle part was improved by overlapping the nozzles whereas there was little difference on the upper and lower part of rice plants. (3) For spraying lower part of rice plant between rows, even flat-fan nozzles and hollow cone nozzle were judged as appropriate, but in order to ensure the uniform coverage, distance between nozzles, recommended to be less than 90cm.

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Soybean Growth and Yield as Affected by Spacing of Drainage Furrows in Paddy Field

  • Cho, Jin-Woong;Lee, Jung-June;Oh, Young-Jin;So, Jung-D.;Won, Jun-Yeon;Kim, Chang-Ho
    • KOREAN JOURNAL OF CROP SCIENCE
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    • v.51 no.1
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    • pp.26-31
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    • 2006
  • This study was conducted to determine the optimum number of inter-rows according to distance of drainage furrow (DF) for running-off excessive-water stress (EWS) in paddy field. The most soil water potential was shown in high ridge (distance of DF by 70 cm) cultivation and the soil water potential showed increasing tendency in over four inter-rows cultivation by DF. The growth of soybean reduced by extended inter-row and its reducing level was high, especially, over four inter-rows (DF distance by 2.8 m) because of EWS. The photosynthetic rate decreased in the more extensive field by distance of DF at V5 and R2 stages, especially, in over four interrows cultivation. Also, root activity decreased at wider DF. The yield was reduced with wider distance of DF more extensively, the highest yield of 270 g per $m^2$ at the every row, but yield showed decreasing tendency at over the $4^{th}$ row (2.8 m) cultivation. Soybean cultivation in paddy field could be founded with DF of every other or $4^{th}$ row.