• 제목/요약/키워드: Resistance in series model

검색결과 183건 처리시간 0.026초

A Simple Model Parameter Extraction Methodology for an On-Chip Spiral Inductor

  • Oh, Nam-Jin;Lee, Sang-Gug
    • ETRI Journal
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    • 제28권1호
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    • pp.115-118
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    • 2006
  • In this letter, a simple model parameter extraction methodology for an on-chip spiral inductor is proposed based on a wide-band inductor model that incorporates parallel inductance and resistance to model skin and proximity effects, and capacitance to model the decrease in series resistance above the frequency near the peak quality factor. The wide-band inductor model does not require any frequency dependent elements, and model parameters can be extracted directly from the measured data with some curve fitting. The validity of the proposed model and parameter extraction methodology are verified with various size inductors fabricated using $0.18\;{\mu}m$ CMOS technology.

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Development of the ice resistance series chart for icebreaking ships

  • Lee, Chun-Ju;Joung, Tae-Hwan;Lew, Jae-Moon
    • International Journal of Naval Architecture and Ocean Engineering
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    • 제10권6호
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    • pp.794-802
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    • 2018
  • The ice resistance series charts for icebreaking ships were developed through a series of systematic model tests in the ice tank of the Korean Research Institute of Ship and Ocean Engineering (KRISO). Spencer's (1992) component-based scaling system for ship-ice model tests was applied to extend the model ship correlations. Beam to draft ratio (B/T), length to beam ratio (L/B), block coefficient ($C_B$) and stem angle (${\alpha}$) were selected as geometric parameters for hull form development. The basic hull form (S1) of twin pod type with B/T of 3.0, L/B of 6.0, $C_B$ of 0.75 and stem angle of $25^{\circ}$ was generated with a modern hull design concept. A total of 13 hulls were designed varying the geometric parameters; B/T of 2.5 and 3.5, L/B of 5.0 and 7.0, $C_B$ from 0.65 to 0.85 in intervals of 0.05, and 5 stem angles from $15^{\circ}$ to $35^{\circ}$. Ice resistance tests were first carried out with the basic hull form in level ice with suitable speed. Four more tests for $C_B$ variations from 0.65 to 0.85 were conducted and two more for beam to draft and length to beam ratios were also performed to study the effect of the geometric parameters on ice resistance. Ice resistance tests were summarized using the volumetric coefficient, $C_V$ ($={\nabla}/L^3$), instead of L/B and $C_B$ variations. Additional model tests were also carried out to account for the effect of the stem angle, ice thickness and ice strength on ice resistance. In order to develop the ice resistance series charts with a minimum number of experiments, the trends of the ice resistance obtained from the experiments were assumed to be similar for other model ship with different geometric parameters. A total of 18 sheets composed of combinations of three different beam to draft ratios and six block coefficients were developed as a parameter of $C_V$ in the low speed regions. Three correction charts were also developed for stem angles, ice thickness and ice strength respectively. The charts were applied to estimate ice resistance for existing icebreaking ships including ARAON, and the results were satisfactory with reasonable accuracy.

비정질 실리코 박막 트랜지스터의 직렬 저항에 관한 분석 (Analysis for Series Resistance of Amorphous Silicon Thin Film Transistor)

  • Kim, Youn-Sang;Lee, Seong-Kyu;Han, Min-Koo
    • 대한전기학회논문지
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    • 제43권6호
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    • pp.951-957
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    • 1994
  • We present a new model for the series resistance of inverted-staggered amorphous silicon (a-Si) thin film transistors (TFT's) by employing the current spreading under the source and the drain contacts as well as the space charge limited current model. The calculated results based on our model have been in good agreements with the measured data over a wide range of applied voltage, gate-to-source and gate-to-drain overlap length, channel length, and operating temperature. Our model shows that the contribution of the series resistances to the current-voltage (I-V) characteristics of the a-Si TFT in the linear regime is more significant at low drain and high gate voltages, for short channel and small overlap length, and at low operating temperature, which have been verified successfully by the experimental measurements.

막표면의 케이크층 세정 방법에 따른 여과 저항값 비교 (Comparison of Filtration Resistances according to Membrane Cleaning Methods)

  • 한송희;장인성
    • 한국환경과학회지
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    • 제25권6호
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    • pp.817-827
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    • 2016
  • The resistance in series model has been frequently used for determination of various filtration resistance to correctly understand the membrane fouling behaviour in MBR (membrane bio-reactor) for wastewater treatment. The cake layer resistance ($R_c$) which is commonly determined by calculation of flux dataset that are obtained empirically before and after removing the cake layer on membrane surface. However, the calculated Rc values are very dependent on the cleaning methods adapted for removal of cake layer. This study investigated how the various cleaning options affect $R_c$. Seven different cleaning methods were employed: i) ultrasonication (100 W, 10 min), ii) ultrasonication (200 W, 60 min), iii) ultrasonication (400 W, 120 min), iv) water rinsing in a shaker (100 rpm, 10 min), v) water rinsing in a shaker (300 rpm, 60 min), vi) water rinsing, vii) sponge scrubbing. For the hydrophilic PES membrane, the cake layer removal efficiencies ranged from 64% to 10%, indicating that the removal of cake layer was highly dependent on the cleaning options. For the hydrophobic PVDF membrane, the cake layer removal efficiencies ranged from 79% to 97%. Consequently, a standardized method for cake layer removal to determine cake resistance ($R_c$) is needed for correct interpretation of the fouling phenomena.

콘테이너선(船)의 파랑중(波浪中) 운동.저항.추진성능(運動.抵抗.推進性能) 연구(硏究) (Ship Motion, Resistance and Propulsive Performance of a Container Ship in Regular Head Waves)

  • 양승일;홍석원;이상무;김은찬
    • 대한조선학회지
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    • 제20권4호
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    • pp.25-32
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    • 1983
  • A series of model testes on a container ship in regular were executed. This paper presents the results of resistance, self-propulsion, and ship motion tests. The experimental results of ship motion measured on a towed model and a self-propelled model were compared with those of Japanese's model test showing fairly good agreements. The results of added resistance tests were compared with those of Japanese' model test and also compared with the calculation results by Gerritsma's method showing somewhat large discrepancies at higher speeds. Also the results of added resistance tests measured on a fixed model were compared with the calculation results by Gerritsma's method. Finally the results of self-propulsion tests were presented.

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고속 소형 어선의 기본선행 개발 (Hull form development of the high speed small fishing boat)

  • 이귀주;좌순원
    • 수산해양기술연구
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    • 제44권1호
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    • pp.68-74
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    • 2008
  • This study is concerned with the development of the basic planing hull form of small fishing boat in 25 knots high speed. A series of model test to determine the optimum performance hull form of actual fishing boat with 10 gross tonnage was carried out for 5 models made available planing hull form in the circulation water channel. Model test was performed with the resistance test to study the hydrodynamic characteristics of model ships and the sinkage and trim measurement to investigate the stability of model ships and also the wave pattern observation to analyze the effectiveness of model ships. As the result, the planing hull form of P-4 with deep V type bow can be derived as the best hull form with good performance especially in ship's resistance efficiency showing less residual resistance and sinkage and trim and the spray effect, etc..

투과증발법을 이용한 감귤 Essence Aroma 모델액의 농축 (Concentration of Citrus Essence Aroma Model Solution by Pervaporation)

  • 이용택;박중원;신동호
    • 멤브레인
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    • 제16권1호
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    • pp.68-76
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    • 2006
  • 본 연구는 투과증발법을 이용하여 수용액 중 미량의 감귤 향 성분을 농축하는 방법으로, 4종류의 실록산계 고분자 복합막을 이용하여 막 종류와 구조에 따른 투과 특성을 살펴보았다. 또한 최적의 막을 선정하여 공급액의 온도와 농도, 순환 유속에 따른 투과 특성을 살펴보고, 이를 resistance-in series model을 이용하여 해석하였다. 4종류의 실록산계 고분자 복합막을 통한 감귤 essence aroma 모델액의 투과 실험에서 지지층이 polyvinylidene fluoride (PVDF)이고 활성층이 polyoctylmethyl siloxane (POMS)인 막이 가장 높은 향 성분 플럭스와 농축계수 값을 나타내었으며, 공급액의 온도와 농도, 순환유속을 변화시키며 투과 실험을 하였다. 그 결과 공급액의 온도와 농도가 증가됨에 따라 향성분의 플럭스는 증가하고 농축계수 값은 감소하였으며 순환유속이 증가됨에 따라 향성분의 플럭스와 농축계수 값 모두 증가하였다.

50노트급 활주형선의 저항성능 개선을 위한 부가물 부착에 관한 실험적 연구 (An experimental study on the improvement of resistance performance by appendage for 50 knots class planing hull form)

  • 이귀주;박나라;이은정
    • 수산해양기술연구
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    • 제41권3호
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    • pp.222-226
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    • 2005
  • A series of model tests carried out at the CWC of WJFEL for the purpose of prediction of resistance for the performance and improvement of resistance by attaching appendage for the ship of 50 knots class planing hull. The resistance performance evaluation has been carried out for the bare hull and for the appendage hull with two different depth of vertical type wedges. In the bare model test, trim and sinkage is calculated for the planing hull and the resistance is calculated. For minimizing the resistance, wedge appendage is attached and tested. Analysis and tests shows that for a 12.5mm wedge, resistance is minimum and overall power tallied to 5636ps.

망간과 휴믹산에 의한 세라믹 막 오염의 제어를 위한 약품 스팀세정의 적용 (Chemically enhanced steam cleaning for the control of ceramic membrane fouling caused by manganese and humic acid)

  • 안선아;박철규;이진산;김한승
    • 상하수도학회지
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    • 제35권6호
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    • pp.425-436
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    • 2021
  • In this study, chemically enhanced steam cleaning(CESC) was applied as a novel and efficient method for the control of organic and inorganic fouling in ceramic membrane filtration. The constant filtration regression model and the resistance in series model(RISM) were used to investigate the membrane fouling mechanisms. For total filtration, the coefficient of determination(R2) with an approximate value of 1 was obtained in the intermediate blocking model which is considered as the dominant contamination mechanism. In addition, most of the coefficient values showed similar values and this means that the complex fouling was formed during the filtration period. In the RISM, R c/R f increased about 4.37 times in chemically enhanced steam cleaning compared to physical backwashing, which implies that the internal fouling resistance was converted to cake layer resistance, so that the membrane fouling hardly to be removed by physical backwashing could be efficiently removed by chemically enhanced steam cleaning. The results of flux recovery rate showed that high-temperature steam may loosen the structure of the membrane cake layer due to the increase in diffusivity and solubility of chemicals and finally enhance the cleaning effect. As a consequence, it is expected that chemically enhanced steam cleaning can drastically improve the efficiency of membrane filtration process when the characteristics of the foulant are identified.

세라믹 막여과 정수처리 공정에서 유입수질 및 막여과유속이 막오염 형성에 미치는 영향 (Effects of membrane fouling formation by feed water quality and membrane flux in water treatment process using ceramic membrane)

  • 강준석;박서경;이정준;김한승
    • 상하수도학회지
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    • 제32권2호
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    • pp.77-87
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    • 2018
  • In this study, the effects of operating conditions on the formation of reversible and irreversible fouling were investigated in the filtration using ceramic membrane for water treatment process. The effect of coagulation pretreatment on fouling formation was also evaluated by comparing the performance of membrane filtration both with and without addition of coagulant. A resistance-in-series-model was applied for the analysis of membrane fouling. Total resistance (RT) and internal fouling resistance (Rf) increased in the membrane filtration process without coagulation as membrane flux and feed water concentrations increased. Internal fouling resistance, which was not recovered by physical cleaning, was more than 70% of the total resistance at the range of the membrane flux more than $5m^3/m^2{\cdot}day$. In the combined process with coagulation, the cake layer resistance (Rc) increased to about 30-80% of total resistance. As the cake layer formed by coagulation floc was easily removed by physical cleaning, the recovery rate by physical cleaning was 54~90%. It was confirmed from the results that the combined process was more efficient to recover the filtration performance by physical cleaning due to higher formation ratio of reversible fouling, resulted in the mitigation of the frequency of chemical cleaning.