• Title, Summary, Keyword: Saturation Factor

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Ammonia Removal Model Based on the Equilibrium and Mass Transfer Principles

  • Yoon, Hyein;Lim, Ji-Hye;Chung, Hyung-Keun
    • Bulletin of the Korean Chemical Society
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    • v.29 no.3
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    • pp.555-561
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    • 2008
  • In air stripping of ammonia from the aqueous solution, a new removal model was presented considering the equilibrium principles for the ammonia in aqueous solution and between the aqueous and air phase. The effects of pH, temperature and airflow rate on the ammonia removal were evaluated with the model. In addition, the saturation degree of ammonia in air was defined and used to evaluate the effect of each experimental factor on the removal rate. As pH (8.9 to 11.9) or temperature (20 to 50 oC) was increased, the overall removal rate constants in all cases were appeared to be increased. Our presented model shows that the degrees of saturation were about the same (0.45) in all cases when the airflow condition remains the same. This result indicates that the effect of pH and temperature were directly taken into consideration in the model equation. As the airflow increases, the overall removal rate constants were increased in all cases as expected. However, the saturation degree was exponentially decreased with increasing the airflow rate in the air phase (or above-surface) aeration. In the subsurface aeration the saturation degree remains a constant value of 0.65 even though the airflow rate was increased. These results indicate that the degree of saturation is affected mainly by the turbulence of the aqueous solution and remains the same above a certain airflow rate.

A Study on Sensitive Cognition for the Physical Factor of Color (색의 물리적 요소에 관한 감성인식 연구)

  • 심준형;이근희;오형술
    • Journal of the Society of Korea Industrial and Systems Engineering
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    • v.18 no.36
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    • pp.31-39
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    • 1995
  • This study reflected sensitivity cognition in using color and evaluated the performance in task regarded GUI environment. Largely, three experiments were conducted. First, the searching time in text environment was compared with the searching time in color environment. Second, to know relationship of hue, saturation, lightness which are factors of color, and searching time, the searching time was measured using two-way ANOVA with interaction with three independent variables: hue, saturation, and distance. Third, sensitivity cognition about color was investigated and the performance of searching task was analyzed in the environment designed by color regarded sensitivity cognition. According to statistical results, the average searching time was decreased about 50.31% in color environment. The searching time was significant among the difference of hue and saturation. For the factor of color, the more the ratio of green and red was increased, the more searching time was decreased. The more the ratio of gray was increased, the more searching time was increased. And the searching time was developed in the environment designed by color regarded sensitivity. The purpose of this study is the presentation of sensitivity realization method and verification in the reflection and application of sensitivity to the industrial environment and design.

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Low Reverse Saturation Current Density of Amorphous Silicon Solar Cell Due to Reduced Thickness of Active Layer

  • Iftiquar, S M;Yi, Junsin
    • Journal of Electrical Engineering and Technology
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    • v.11 no.4
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    • pp.939-942
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    • 2016
  • One of the most important characteristic curves of a solar cell is its current density-voltage (J-V) curve under AM1.5G insolation. Solar cell can be considered as a semiconductor diode, so a diode equivalent model was used to estimate its parameters from the J-V curve by numerical simulation. Active layer plays an important role in operation of a solar cell. We investigated the effect thicknesses and defect densities (Nd) of the active layer on the J-V curve. When the active layer thickness was varied (for Nd = 8×1017 cm-3) from 800 nm to 100 nm, the reverse saturation current density (Jo) changed from 3.56×10-5 A/cm2 to 9.62×10-11 A/cm2 and its ideality factor (n) changed from 5.28 to 2.02. For a reduced defect density (Nd = 4×1015 cm-3), the n remained within 1.45≤n≤1.92 for the same thickness range. A small increase in shunt resistance and almost no change in series resistance were observed in these cells. The low reverse saturation current density (Jo = 9.62×10-11 A/cm2) and diode ideality factor (n = 2.02 or 1.45) were observed for amorphous silicon based solar cell with 100 nm thick active layer.

Electron Tunneling Characteristics of PtSi-nSi Junctions according to Temperature Variations (온도변화에 따른 백금 실리사이드-엔 실리콘 접합의 전자 터널링 특성)

  • 장창덕;이정석;이광우;이용재
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.87-91
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    • 1998
  • In this paper, We analyzed the current-voltage characteristics with n-type silicon substrates concentration and temperature variations (Room temperature, 50$^{\circ}C$, 75$^{\circ}C$) in platinum silicide and silicon junction. The electrical parameters of measurement are turn-on voltage, saturation current, ideality factor, barrier height, dynamic resistance in forward bias and reverse breakdown voltage according to variations of junction concentration of substrates and measurement temperature variations. As a result, the forward turn-on voltage, reverse breakdown voltage, barrier height and dynamic resistance were decreased but saturation currents and ideality factor were increased by substrates increased concentration variations in platinum silicide and n-silicon junction. In increased measurement temperature (RT, 50$^{\circ}C$, 75$^{\circ}C$), the extracted electrical parameter values of characteristics were rises by increased temperature variations according to the forward and reverse bias.

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Variation of Slope Stability under rainfall considering Train Speed (열차의 속도 하중을 고려한 강우시 성토사면의 안정성 변화)

  • 김정기;김현기;박영곤;신민호;김수삼
    • Proceedings of the KSR Conference
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    • pp.601-607
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    • 2002
  • Infiltration of rainfall causes railway embankment to be unstable and may result in failure. Basic relationship between the stability of railway embankment and rainfall introducing the partial saturation concept of ground are defined to analyze the stability of embankment by rainfall. A pressure plate test is also peformed to obtain soil-water characteristic curve of unsaturated soils. Based on this curve, the variables in the shear strength function and permeability function are also defined. These functions are used fur the numerical model for evaluation of railway embankments under rainfall. As comparing the model and case studies, the variation of shear strength, the degree of saturation and pore-water pressure for railway embankment during rainfall can be predicted and the safety factor of railway embankment can be expressed as the function of rainfall amount namely rainfall index. Therefore, the research on safety factor on railway embankment considering train speed and rainfall infiltration with the variation of rainfall intensity and rainfall duration was carried out in this paper.

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A Study on TRANSYT Model-embedded Parameters (TRANSYT 모델의 내재 모개변수에 관한 연구)

  • 도철웅
    • Journal of Korean Society of Transportation
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    • v.6 no.1
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    • pp.55-64
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    • 1988
  • Prior to using any computer model, the program-embedded palameters showing significant differences from real world should be calibrated. This is especially true when the model is expected to be used fro various roadway and traffic condition. The calibration of TRANSYT model was conducted for the parameters of start-up delay, and lag, stop penalty(K), platoon dispersion factor, and saturation flow rate. The values of the parameters were obtained by theoretical methods from actual field measurements for discharging and arrival pattern. The sites elected for the study was an intersection of Dongil-Ro and Hwarang-Ro, and a 334 meter downstrean section from the intersection stop line on westbound Hwarang-Ro. The study results showed that the start-up delay was 2.6 sec, end lag was 1.0 sec, saturation flow rate was 2287 pcphgpl, platoon dispersion factor was 0.2-03, and stop penalty(K) was 32. However, since these parameters re apt to depend on traffic and roadway condition, it is doubtful whether the obtained values will be applicable to the area-wide situation other than this particular site.

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Analytical Modeling for Circuit Simulation of Amorphous Silicon Thin Film Transistors (비정질 실리콘 박막 트랜지스터의 회로 분석을 위한 해석적 모델링)

  • 최홍석;박진석;오창호;한철희;최연익;한민구
    • The Transactions of the Korean Institute of Electrical Engineers
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    • v.40 no.5
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    • pp.531-539
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    • 1991
  • We develop an analytical model of the static and the dynamic characteristics of amorphous silicon thin film transistors (a-Si TFTs) in order to incorporate into a widely used circuit simulator such as SPICE. The critical parameters considered in our analytical model of a-Si TFT are the power factor (XN) of saturation source-drain current and the effective channel length (L') at saturation region. The power factor, XN must not always obey so-called

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Analysis of a Crack in Ferroelectric Ceramics Subjected to Electric Fields (전기장을 받는 강유전체 세라믹내의 균열 해석)

  • 범현규;김인옥
    • Journal of the Korean Society for Precision Engineering
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    • v.20 no.6
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    • pp.138-144
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    • 2003
  • A crack in a ferroelectric ceramic subjected to an electric field is analyzed. The boundary of the electrical saturation zone is estimated based on the finite-width saturation zone model, which is analogous to a finite-width Dugdale zone model for mode III. It is shown that the shape and size of the switching zone depends strongly on the boundary of the electrical saturation zone and the ratio of the coercive electric field to the yield electric field. The crack tip stress intensity factor under small scale conditions is evaluated by employing the model of electric nonlinear domain switching. It is found that fracture toughness of the ferroelectric material may be increased or decreased depending on the material property of electrical nonlinearity.

The study on effects of porosity grain size, magnetization and anisotropy field on the properties of ferromagnetic resonance (다결정 Mg-페라이트의 기공율, 입경, 포화 자화 및 이방성 자기장이 강자성 공명 특성에 미치는 영향 연구)

  • 김진호;주승기;최덕균
    • Journal of the Korean Institute of Telematics and Electronics A
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    • v.32A no.1
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    • pp.97-102
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    • 1995
  • The ferromagnetic resonance properties of Mg ferrites which have various porosity grain size, and saturation magnetization are measured at one frequency. This allows a determination of the anisotropy field(Ha). The saturation magnetization multiplied by porosity is the resonance magnetic field. As the saturation magnetization increases, the linewidth decerases due to decrement of magnetic inhomogenity in sample. the porosity is a major factor broadening the linewidth for Mg ferrite when porosity is more thatn 6%, and the anisotropy field is dominant when porosity is less than 6%.

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Thermal Influential factors of Energy pile considering Ground saturation (지반 포화조건을 고려한 에너지파일의 열적거동 인자분석)

  • Song, Jin-Young;Paek, Jin-Yeol;Yun, Tae-Sup;Jeong, Sang-Seom
    • Proceedings of the Korean Geotechical Society Conference
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    • pp.104-112
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    • 2010
  • The thermal influential factor of energy pile system is investigated by considering the seasonal effect, saturation of ground, and fluid velocity based on the finite volume method. Analysis includes the evaluation of thermal resistance and corresponding heat exchange rate for each case. It is shown that the efficiency of heat exchange rate is more pronounced with higher fluid velocity due to the larger number of circulation for a given period. Through the parametric studies, it is also found that the degrees of saturation a little influenced thermal effect during 8 hours of operational scenario.

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