• Title, Summary, Keyword: 충전율

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Apparent Densification Rate and Initial Permeability of NiCuZn Ferrite Depended on Relative Packing Density (NiCuZn Ferrite의 겉보기 고화속도와 초기투자율의 충진율 의존성에 관한 연구)

  • 류병환;이정민;고재천
    • Journal of the Korean Institute of Resources Recycling
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    • v.7 no.4
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    • pp.27-34
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    • 1998
  • In this research, the processing control of NiCuZn Ferrite (NCZF) had been studied. NiCuZn Ferrite, which calcined at $700^{\circ}C$ for 3 bours, was ball milled for about 60 hours to ill김ke a size of $0.5\mu\;extrm{m}$ followed by granulation using spray dryer Apparent densincatioo rate and initial permeability of NiCuZn Ferrite with an initial packing density had been investigated as f follows. 1.The relative packing density of NCZF green body increas$\xi$d in the range of 48.6-56.8% with an increased forming pressure of 20-170 MPa. 2. The higher the relative pac퍼ng density of NCZF and the sintering temperature are, the higher the initial densification rate. The increased bulk rlcnsity of NCZF was attributed to the densification rate with decreased open pore and increased closed pore as the relative packing density, sintering temperature, and sinteriog tim$\xi$ increased. 3. The initial P permeability of NCZF with constant composition is logarithmically proportional to the bulk density of NCZF sintered at $875~925^{\circ}C$ for 0-5h, and strongly depended on the relative packing density of NCZF green body. The empirical equation is as f follows; log $\mu$i=$G1{\times}BD$+$G2{\times}RPD$+b(0);where, G1, G2; gradient, B.D: bulk density, RPD; relative packing density, b(0); intercept.

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Advanced Water Treatment of High Turbidity Source by Hybrid Process of Ceramic Microfiltration and Activated Carbon Adsorption: Effect of GAC Packing Fraction (세라믹 정밀여과 및 활성탄 흡착 혼성공정에 의한 고탁도 원수의 고도정수처리: 입상 활성탄 충전율에 의한 영향)

  • Park, Jin-Yong;Lee, Hyuk-Chan
    • Membrane Journal
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    • v.18 no.3
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    • pp.191-197
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    • 2008
  • In this study, we used hybrid module that was composed of packing granular activated carbon (GAC) between module inside and outside of ceramic microfiltration membrane for advanced drinking water treatment. Instead of natural organic matters (NOM) and fine inorganic particles in natural water source, synthetic water was prepared with humic acid and kaolin. Packing fraction of GAC was changed from 0 to 24.05% to see effect of packing fraction. As a result, changing curves of resistance of membrane fouling ($R_f$) and permeate flux (J) during 3 h operation were almost overlapped independent of packing fraction of GAC. Treatment efficiencies of turbidity were very high above 99.46% at all packing fractions of GAC. And treatment efficiency of NOM, which was measured by $UV_{254}$ absorbance, was the highest value of 99.43% at packing fraction of 24.05%. Then, we operated the hybrid process during 13 h at packing fraction of 24.05%. As a result, J was rapidly dropped according to increase of membrane fouling within initial 1 h of operation, and almost constant after 3 h. And treatment efficiencies of turbidity and NOM were stable and high values of 99.52% and 96.63%, respectively.

Experimental and Numerical Studies on the Flow Characteristics in Resin Transfer Molding Process (수지이동 성형공정의 유동특성에 관한 실험 및 수치모사 연구)

  • 이미혜
    • The Korean Journal of Rheology
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    • v.7 no.2
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    • pp.139-149
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    • 1995
  • 실제 복합재료 제조공정에 널리 이용되는 등방성 탄소섬유직조와 에폭시수지에 대 해서 수지의 유동을 일방향으로 근사하여 비정상상태 투과계수와 모세관압을 측정하는 실험 을 수행하였고 적층된 섬유직조의 기공율, 금형 주입압력 그리고 섬유직조의 적층수에 따른 수지유동특성을 분석하였다. 또한 금형 충전과정에 대한 유동가시화 실험을 수행하여 유동 선단과 충전시간을 측정하였다. 전체 조업압력에 미치는 모세관압의 영향을 규명하기 위해 일정 유입압력에 따른 금형충전과정에 대하여 유한요소/관할부피 방법을 이용한 수치모사를 수행하였다. 함침공정의 수지유동에서 비정상상태 투과계수는 섬유직조의 기공율에 따라 급 격히 증가하였고 에폭시수의 표면장력에 기인한 모세관압은 기공율 감소에 따라 급격히 증 가하였다. 동일한 기공율에서 섬유직조의 적층수가 증가함에 따라 투과계수와 모세관압은 모두 증가하는 경향을 보였다. 또한실험에서 측정한 모세관압을 고려하여 유동선단과 금형 충전시간을 수치모사방법으로 예측ㄷ한 결과는 유동가시화 실험에의한 결과와 잘 일치함을 보였다. 이결과로부터 낮은 압력에서 조업하는 RTM공정에서 모세관압효과는 유동선단과 금형 충전시간을 예측하는데 기여함을 알수 있다.

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Power Charge Scheduling and Charge-Ready Battery Allocation Algorithms for Real-Time Drones Services (실시간 드론 서비스를 위한 전원 충전 스케쥴링과 충전 배터리 할당 알고리즘)

  • Tajrian, Mehedi;Kim, Jai-Hoon
    • KIPS Transactions on Computer and Communication Systems
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    • v.8 no.12
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    • pp.277-286
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    • 2019
  • The Unmanned Aerial Vehicle (UAV) is one of the most precious inventions of Internet of things (IOT). UAV faces the necessity to charge battery or replace battery from the charging stations during or between services. We propose scheduling algorithms for drone power charging (SADPC). The basic idea of algorithm is considering both a deadline (for increasing deadline miss ratio) and a charging time (for decreasing waiting time) to decide priority on charging station among drones. Our simulation results show that our power charging algorithm for drones are efficient in terms of the deadline miss ratio as well as the waiting time in general in compare to other conventional algorithms (EDF or SJF). Also, we can choose proper algorithms for battery charge scheduling and charge ready battery allocation according to system parameters and user requirements based on our simulation.

A study on the Properties for Structural Behavior of High-Performance Concrete Filled Square Steel Tube Columns -The Behavior Properties by Loading Conditions- (고성능 콘크리트를 충전한 각형강관 기둥의 구조적 거동 특성에 관한 연구 -재하조건별 거동특성-)

  • Park, Jung Min;Lee, Sung Jo;Kim, Wha Jung
    • Journal of Korean Society of Steel Construction
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    • v.10 no.2
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    • pp.177-186
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    • 1998
  • The concrete filled steel tubular column have to superior in compressive load carrying capacity, compared with same section typed hollow steel tube column, and have many excellent structural properties, such as stiffness improvement by filled concrete, improvement of ductility by reinforced effect of local buckling, and the like. However, it has not clear the effect of interaction between steel tube and filled concrete, stress portion ratio and fracture mechanism of concrete. This study investigated to structural properties for high strength concrete filled steel tube column by loading conditions through a series of experiments. Especially, this study investigated the properties of structural behaviors for concrete filled steel tube column stress ratio by loading conditions and failure mechanism of filled concrete.

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A Theoretical Study on Burning Area of Wire-Embedded Propellant Grains (금속선 삽입 추진제 그레인 연소면적에 대한 이론적 연구)

  • 오종윤
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • pp.32-32
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    • 1998
  • 고체 로켓 모타 추진제 그레인은 크게 단면 연소형 그레인(end-burning grain)과 내면 연소성 그레인(perforated grain)으로 분류할 수 있다. 단면 연소형 그레인은 부피충전율이 크고 구조적 안전성이 우수한 장점이 있으나 연소면적이 작은 단점이 있고, 내면 연소형 그레인은 연소면적이 큰 장점이 있으나 부피 충전율이 작은 단점이 있다. 따라서 단면 연소형 그레인의 장점인 높은 충전율을 유지하면서 연소면적을 증대시키는 효율적인 방법으로 열전도율이 높은 금속선을 단면 연소 그레인에 삽입시키는 방법이 있다. 높은 열전도율로 인하여 금속선을 따라 연소속도가 빨라져 연소면적이 증가하게 되는데, 금속선이 없을 때의 연소속도와의 비를 연소속도 증가 비라 한다. 이는 추진제 종류, 금속선 재질, 굵기 등에 따라 달라지고, 실험실에서 strand burner test로 구할 수 있다.

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An Experimental Study on the Behaviours of Hollow CFT Column Subjected to Axial Load (중공 콘크리트충전 각형강관 기둥의 거동에 관한 연구 (I. 중심 압축실험))

  • Kim, Cheol-Hwan;Kim, Jong-Kil
    • Journal of Korean Association for Spatial Structures
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    • v.6 no.3
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    • pp.69-76
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    • 2006
  • Concrete Filled Steel Tube (CFT) system is advantageous because it increases the load-carrying capacity without increasing the size of column. However CFT system has many benefits, it is not applied to field generally because of its heavyweight and difficulty of concrete filling method. As a solution to these problems, we proposed concrete filled steel tube column with hollow made by factory-manufactured PC method. The hollow concrete filled steel tube system is expected to obtain the high strength and high capacity of deformation despite it is a lightweight. This study deals with mechanical properties, strength and deformation, of hollow concrete filled steel tube subjected to axial load. 9 specimens were tested to examine mechanical properties closely, and the following results were obtained: All specimens basically showed higher initial rigidity and maximum strength with increased concrete filling rate. And most specimens showed almost linear behavior until around 80% of maximum strength regardless of filling rate, it is estimated that the elastic range is up to a half of the maximum strength which is the yield strength level.

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An Effective Wireless Power Transfer Technique using Permalloy (Permalloy를 이용한 효율적 인 무선 전력송신 기술)

  • Hwang, Jae-Young;Chung, Yeon-Ho
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.14 no.3
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    • pp.678-683
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    • 2010
  • This paper presents a wireless (contactless) charging technique with a new core material called permalloy. For charging portable devices wirelessly, ferrosilicon or ferrite has been conventionally used. Due to high permeability of permalloy, charging efficiency can be significantly improved and subsequently this high efficiency increases charging distance between charger and portable devices. Comparative experimental studies demonstrate that the charging performance and efficiency with permalloy employed are significantly improved. The proposed wireless charging techniques can be used to charge portable devices efficiently.

Numerical Analysis on Effective Countermeasure for Ground Subsidence due to Mining Hazard (광해로 인한 지반침하의 효율적인 보강방안에 관한 수치해석)

  • Hong, Won-Pyo;Lee, Jae-Ho;Hur, Se-Young
    • Journal of the Korean Geosynthetics Society
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    • v.6 no.4
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    • pp.7-13
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    • 2007
  • When the structure such as roadway, railway are constructed on abandoned coal mine area, the countermeasure to prevent settlements is necessary. In this study, numerical analyses are performed to evaluate the effect of the various countermeasures. As a results, the method which is filling the coal mine is more effective than that of reinforcing the ground above the coal mine. The ground settlement decreases hyperbolically with increasing the filling ratio of the coal mine. Also, the relationship between the filling ratio and the settlement reduction ratio is discussed precisely.

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Fluoride Removal by Granular Aluminium Bipolar Packed Bed Electrolytic Cell (입자상 알루미늄 충전복극전해조에 의한 불소제거)

  • Ha, Ji-Young;Park, Jung-Hoon;Woo, Sung-Hoon;Park, Seung-Cho
    • Journal of Korean Society of Environmental Engineers
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    • v.29 no.6
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    • pp.684-688
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    • 2007
  • The results of potentiostatic electrolysis of aqueous solution containing fluoride by bipolar packed bed electrolytic cell filled with granular aluminium were summarized. Removal efficiency of fluoride ion which it analyzed with ion chromatograph were 53, 73, 90% in applied voltage. Control the concentration of supporting electrolyte were 10, 30, 50, 70 mg/L and volume of packing material were 0, 25, 50, 75%, respectively, the quantity of electricity was $2.58A{\cdot}hr$ when the concentration of supporting electrolyte was 50 mg/L and the volume of packing material was 75%. As the results of electrolytsis of fluoride aqueous solution containing fluoride 10, 30, 50, 70 mg/L for 3 hours at 10 V, the removal efficiency of fluoride were 93.3, 80, 68.6%. Then the quantity of electricity were 2.58, 3.89, $5.43A{\cdot}hr$ and the fluoride removal amounts per quantity of electricity were 4.0, 3.5, $2.0mg/A{\cdot}hr$.