• Title/Summary/Keyword: Control Parameter

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Development of a Water Quality Model for Streams in an Upland Agricultural Watershed (농촌 유역 상단부의 소하천에서 수질예측모형의 개발)

  • Choe, Hye-Suk;O, Gwang-Jung;Kim, Sang-Hyeon
    • Journal of Korea Water Resources Association
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    • v.33 no.1
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    • pp.73-85
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    • 2000
  • A water quality model was developed for small stream at a upland agricultural watershed. A control volume method was employed to digest the severe variability of stream shape, water quality and discharge at small streams. We estimated optimum reaction coefficients and model structure using a random number generation technique. The index of agreement and coefficient of efficiency were introduced for the model calibration criterion. As the result, the reliability of model parameter estimation could be improved. The applicability of model was tested by a set of sampling results at Yongduckchun in Kimhae. The variability of water quality reaction coefficient was explored through the observed data and using the developed model. model.

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Change the Properties of Amorphous Carbon Hardmask Film Prepared with the Variation of Process Parameters in Plasma Enhanced Chemical Vapor Depostion Systems

  • Kim, Seok Hwan;Yeo, Sanghak;Yang, Jaeyoung;Park, Keunoh;Hur, Gieung;Lee, Jaeho;Lee, Jaichan
    • Proceedings of the Korean Vacuum Society Conference
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    • 2014.02a
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    • pp.381.2-381.2
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    • 2014
  • In this study the amorphous carbon films were deposited by PECVD at the substrate temperature range of 250 to $600^{\circ}C$, and the process conditions of higher and lower precursor flow rate, respectively. The temperature was a main parameter to control the density and mirco-structures of carbon films, and their's properties depended with the process temperatrue are changed by controlling precursor flow rate. The precursor feeding rate affect on the plasma ion density and a deposition reactivity. This change of film properties was obtained the instrinsic stress, FT-IR & Raman analysis, refractive index (RI) and ext. coef. (k) measured by ellipsometer. In the process conditions of lower and higher flow rate of precursor it had a different intrinsic stress as a function of the substrate temperature.

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Aflatoxin-mediated Sperm and Blood Cell Abnormalities in Mice Fed with Contaminated Corn

  • Fapohunda, S. O.;Ezekiel, C. N.;Alabi, O. A.;Omole, A.;Chioma, S. O.
    • Mycobiology
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    • v.36 no.4
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    • pp.255-259
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    • 2008
  • The effect of aflatoxin-contaminated corn on albino mice was investigated using the sperm morphology assay. Blood parameter levels including; total white blood cells (WBC), total red blood cells (RBC), packed cell volume (PCV), serum bilirubin (SB) and fasting blood sugar (FBS) were also determined in the tested mice. Test mice were exposed to aflatoxin-contaminated corn (contamination level of 100 ppb) for $1{\sim}4$ weeks while aflatoxin-free corn and cyclophosphamide were used as negative and positive controls, respectively. Sperm cells showed varieties of morphological abnormality when assessed after 5 weeks. The percentage frequencies of the negative and positive controls were 18.8% and 48.87%, respectively, while the percentage abnormalities for the 1, 2, 3 and 4 weeks exposures were 41.38%, 48.17%, 57.13% and 61.67%, respectively. PCV, WBC, total bilirubin and glucose level values of mice in all concentrations were higher and statistically significant as compared to the negative control values using Dunnett's test. Therefore, abnormal sperm cell induction is concentrationdependent such that continuous consumption of aflatoxin-contaminated corn is capable of negatively affecting spermatogenesis by inducing or increasing the frequency of morphologically abnormal sperm cells produced.

Modeling of Liquid Emulsion Membrane for Organic Acid Separation (유기산의 분리를 위한 유화액막의 수학적 모델)

  • Mok, Young Sun;Lee, Won Kook
    • Membrane Journal
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    • v.5 no.1
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    • pp.44-57
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    • 1995
  • A mathematical model was proposed to describe the behavior of the liquid emulsion membrane(LEM) conraining sodium carbonate as internal stripping reagent. Experimental results of the batch extraction of lactic acid were compared with computed results by using the model. it was found that the model computations could predict fairly well the effects of parameter variations such as the carrier concentration, the stripping reagent concentration, the stirrer speed and the treatment ratio. An attempt has been made to reduce emulsion swelling which is one of the main problem of LEM. As the additives for swelling control, liquid paraffin, n-decanol, cyclohexanone and Span 85 were used. All the additives that were investigated tend to reduce the quantity of swelling to some extent. Cyclohexanone was found not only to reduce the swelling but also to increase largely the acid transport rate.

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The Optimization of Biohydrogen Production Medium by Dark Fermentation with Enterobacter aerogenes (Enterobacter aerogenes의 혐기발효에 의한 바이오 수소 생산 배지의 최적화)

  • Kim, Kyu-Ho;Choi, Young-Jin;Kim, Eui-Yong
    • KSBB Journal
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    • v.23 no.1
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    • pp.54-58
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    • 2008
  • Hydrogen is considered as an energy source for the future due to its environmentally friendly use in fuel cells. A promising way is the biological production of hydrogen by fermentation. In this study, the optimization of medium conditions which maximize hydrogen production from Enterobacter aerogenes KCCM 40146 were determined. As a result, the maximum attainable cumulative volume of hydrogen was 431 $m{\ell}$ under the conditions of 0.5M potassium phosphate buffer, pH 6.5 medium containing 30 g/L glucose. The best nitrogen sources were peptone and tryptone for the cell growth as well as hydrogen production. The control of cell growth rate was found to be a important experimental parameter for effective hydrogen production

Composite Differential Evolution Aided Channel Allocation in OFDMA Systems with Proportional Rate Constraints

  • Sharma, Nitin;Anpalagan, Alagan
    • Journal of Communications and Networks
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    • v.16 no.5
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    • pp.523-533
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    • 2014
  • Orthogonal frequency division multiple access (OFDMA) is a promising technique, which can provide high downlink capacity for the future wireless systems. The total capacity of OFDMA can be maximized by adaptively assigning subchannels to the user with the best gain for that subchannel, with power subsequently distributed by water-filling. In this paper, we propose the use of composite differential evolution (CoDE) algorithm to allocate the subchannels. The CoDE algorithm is population-based where a set of potential solutions evolves to approach a near-optimal solution for the problem under study. CoDE uses three trial vector generation strategies and three control parameter settings. It randomly combines them to generate trial vectors. In CoDE, three trial vectors are generated for each target vector unlike other differential evolution (DE) techniques where only a single trial vector is generated. Then the best one enters the next generation if it is better than its target vector. It is shown that the proposed method obtains higher sum capacities as compared to that obtained by previous works, with comparable computational complexity.

Shape Optimization of a Switched Reluctance Motor Having 6/4 Pole Structure for the Reduction of Torque Ripple Using Response Surface Methodology (반응표면법을 이용한 6/4극 구조를 갖는 스위치드 릴럭턴스 모터의 토크 리플 저감을 위한 형상 최적설계)

  • Choi, Yong-Kwon;Yoon, Hee-Sung;Koh, Chang-Seop
    • The Transactions of the Korean Institute of Electrical Engineers B
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    • v.55 no.12
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    • pp.608-616
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    • 2006
  • Recently, a switched reluctance motor is widely used in various industries because it has many advantages such as a simple structure, robustness, less maintenance, high torque/weight ratio, and easy speed control over other types of motors. However, a switched reluctance motor inherently produces acoustic noise and vibration caused by torque ripple. Applications of these motors where silent operation is desirable have thus been limited. In this paper, a new stator pole face having a non-uniform air-gap and a pole shoe attached to the lateral face of the rotor pole are suggested in order to minimize torque ripple. The effects of each design parameter are validated using a time-stepping finite element method. The parameters are optimized by utilizing response surface method (RSM) combined with (1+1) evolution strategy. The result shows that the optimized shape gives higher average torque and drastically reduced torque ripple.

Impacts of Process and Design Parameters on the Electrical Characteristics of High-Voltage DMOSFETs (공정 및 설계 변수가 고전압 LDMOSFET의 전기적 특성에 미치는 영향)

  • 박훈수;이영기
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.17 no.9
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    • pp.911-915
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    • 2004
  • In this study, the electrical characteristics of high-voltage LDMOSFET fabricated by the existing CMOS technology were investigated depending on its process and design parameter. In order to verify the experimental data, two-dimensional device simulation was carried out simultaneously. The off- state breakdown voltages of n-channel LDMOSFETs were increased nearly in proportional to the drift region length. For the case of decreasing n-well ion implant doses from $1.0\times{10}^{13}/cm^2$ to $1.0\times{10}^{12}/cm^2$, the off-state breakdown voltage was increased approximately two times. The on-resistance was also increased about 76 %. From 2-D simulation, the increase in the breakdown voltage was attributed to a reduction in the maximum electric field of LDMOS imolanted with low dose as well as to a shift toward n+ drain region. Moreover, the on- and off-state breakdown voltages were also linearly increased with increasing the channel to n-tub spacing due to the reduction of impact ionization at the drift region. The experimental and design data of these high-voltage LDMOS devices can widely applied to design smart power ICs with low-voltage CMOS control and high-voltage driving circuits on the same chip.

3-D Flow Analysis for Compression Molding of Fiber-Reinforced Polymeric Composites with Ratio of Extensional & Shear Viscosity (인장 및 전단점성비를 고려한 섬유강화 플라스틱 복합재의 압축성형에 있어서 3차원 유한요소해석)

  • 조선형;윤두현;김형철;김이곤
    • Composites Research
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    • v.12 no.1
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    • pp.11-18
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    • 1999
  • The compression molding is widely used in the automotive industry to produce products that are large, thin, lightweight and stiff. The molded product is formed by squeezing a fiber-reinforced plastic composites. During a molding process of fiber reinforced thermoplastic composites, control of filling patterns in mold, orientation and distribution of fibers are needed to predict the effects of molding parameters on the flow characteristics. It is the objective of this paper to develop an isothermal compression molding simulation that can handle both thin and thick charges and motion of the flow front, and can predict pressure distributions and accurate velocity gradients. The composites are treated as an incompressible Newtonian fluid. The effects of slip parameter $\alpha$ and extensional/shear viscosity ratio $\zeta$ on the mold filling parameters are also discussed.

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Robust Rear Center-Hinge Bracket Optimization Based on Taguchi Method (다구찌 방법을 활용한 Rear Center-Hinge Bracket 강건 설계)

  • Jung, Sebin;Kim, Minho
    • Transactions of the Korean Society of Automotive Engineers
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    • v.22 no.3
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    • pp.203-209
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    • 2014
  • The rear center-hinge bracket is designed for supporting and folding the rear-seat backrest. This bracket needs to be strong enough to be able to rigidly hold the rear-seat backrest and to withstand luggage loads from the car trunk that are generated when a vehicle is driving on the roads. Particularly, current accident studies report that many serious occupant injuries occurred when the rear-seat back easily folded inward toward the car interior, driven by the luggage loads in the trunk. Given this fact, the robust design of the rear center-hinge bracket that mainly supports the rear backrest has become more important for providing customer safety and preventing high warranty and durability problems. However, none of the studies have emphasized its significant role and considered its robust optimization. Therefore, this paper presents how the hinge-bracket design is optimized based on an application of the finite-element method coupled with the parameter design using Taguchi's design experiment. Finally, Taguchi method's application optimizes a robust center-hinge bracket that shows more rigid performance although it has lighter weight and thinner thickness.