• Title, Summary, Keyword: attrition

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Reactivity and Attrition Resistance of Three Oxygen Carrier Particles for Chemical-Looping Combustor (매체순환식 가스연소기 적용을 위한 세 가지 산소공여입자들의 반응성 및 내마모성)

  • Ryu, Ho-Jung;Jin, Gyoung-Tae
    • Transactions of the Korean hydrogen and new energy society
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    • v.15 no.3
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    • pp.208-219
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    • 2004
  • To find a suitable oxygen carrier particle for a 50kW chemical-looping combustor, which was designed and installed to demonstrate continuous oxidation and reduction, three oxygen carrier particles(NiO/bentonite, $NiO/NiAl_2O_4$, $CoO_x/CoAl_2O_4$) were prepared. The reactivity and the attrition resistance of particles were measured and investigated by a thermo-gravimetrical analyzer and an attrition test apparatus respectively. From the viewpoints of oxygen transfer capacity, optimum reaction temperature(operating temperature range), reaction rate, carbon deposition rate, and attrition resistance, NiO/bentonite particle showed better performance than the other particles, therefore we selected NiO/bentonite particle as an optimum oxygen carrier particle.

Recycling Method of Used Indium Tin Oxide Targets (폐 인듐주석산화물 타겟의 재활용 기술)

  • Lee, Young-In;Choa, Yong-Ho
    • Korean Journal of Materials Research
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    • v.22 no.4
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    • pp.174-179
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    • 2012
  • In this study, we demonstrated a simple and eco-friendly method, including mechanical polishing and attrition milling processes, to recycle sputtered indium tin oxide targets to indium tin oxide nanopowders and targets for sputtered transparent conductive films. The utilized indium tin oxide target was first pulverized to a powder of sub- to a few- micrometer size by polishing using a diamond particle coated polishing wheel. The calcination of the crushed indium tin oxide powder was carried out at $1000^{\circ}C$ for 1 h, based on the thermal behavior of the indium tin oxide powder; then, the powders were downsized to nanometer size by attrition milling. The average particle size of the indium tin oxide nanopowder was decreased by increasing attrition milling time and was approximately 30 nm after attrition milling for 15 h. The morphology, chemical composition, and microstructure of the recycled indium tin oxide nanopowder were investigated by FE-SEM, EDX, and TEM. A fully dense indium tin oxide sintered specimen with 97.4% of relative density was fabricated using the recycled indium tin oxide nanopowders under atmospheric pressure at $1500^{\circ}C$ for 4 h. The microstructure, phase, and purity of the indium tin oxide target were examined by FE-SEM, XRD, and ICP-MS.

Recent Trends in HR as Useful Retention Strategy in Indian Information Technology (IT) Sector

  • Potluri, Rajasekhara Mouly;V.S., Mangnale;Challa, Siva Kumar;Challagundla, Srilakshmi
    • The Journal of Distribution Science
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    • v.12 no.1
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    • pp.29-33
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    • 2014
  • Purpose - The focal point of this research is to study the implications of retention, various reasons for attrition and also different ways to control attrition along with the employee retention strategies implementing by the Indian IT sector. Research design, data and methodology - After thorough literature review on employee attrition and retention, questionnaire has prepared to collect the opinions of 200 employees which were chosen from 20 IT companies (10 each from large and medium size companies) with simple random sampling technique and also gathered the opinion of these companies HR managers on strategies they are implementing to retain their talent pool through personal and telephonic interviews. Results -The research completely limited to the IT companies located in the city of Pune which is emerged as a new IT hub of India. The collected data was analyzed with Microsoft Excel and frequency distribution. Conclusions - The researchers identified job associated, compensation related and inter-personal relations for quitting their positions along with the outlook of Indian IT companies related to the identification and implementation of retention strategies like incessant hikes in compensation package, improved working conditions, continuous introduction of employee welfare facilities, and genuine promotional policy, recognition and rewards, career planning and development, and exemplary leadership.

Phase Changes and Microstructural Properties of Ti Alloy Powders Produced by using Attrition Milling Method (어트리션 밀링법으로 제조된 티타늄합금의 상변화 및 미세조직특성)

  • Cha, Sung-Soo
    • The Journal of Korean Academy of Dental Technology
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    • v.23 no.1
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    • pp.9-19
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    • 2001
  • Microstructure and phase transformation of Ti-Ni-Cu alloy powders produced by using attrition milling method were studied. Mixed powders of Ti-(50-X)Ni-XCu ($X=0{\sim}20$ at%) in composition range were mechanically alloyed for maximum 20 hours by using SUS 1/4" ball in argon atmosphere. Ball to powder ratio was 50: 1 and impeller speed was 350rpm. Mechanically alloyed with attrition millimg method. powder was heat treated at the temperature up to $850^{\circ}C$ for 1 hour in the $10^{-6}$ torr vacuum. Ti-Ni-Cu alloy powders have been fabricated by attrition milling method. and then phase transformation behaviours and microstructual properties of the alloy powders were investigated to assist in improving the the high damping capacity of Ti-Ni-Cu shape memory alloy powders. The results obtained are as follows: 1. After heat treating of fully mechanically alloyed powder at $850^{\circ}C$ for 1hour. most of the B2 and B 19' phases was formed and $TiNi_3$ were coexisted. 2. The B 19' martensite were formed in Ti-Ni-Cu alloy powders whose Cu-content is less than 5a/o. where as the B19 martensite in those whose Cu-content is more than 10at%. 3. The powders of as-milled Ti-Ni-Cu alloys whose Cu-contents is less than 5at% are amorphous. whereas those of as-milled Ti-Ni-Cu alloys whose Cu-content is more than 10at% are crystalline. This means that Cu addition tends to suppress amorphization of Ti-Ni alloy powders.

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Particle Attrition Characteristics in a Bubbling Fluidized Bed Under High Temperature and High Pressure Conditions (고온 고압 조건하의 기포유동층 반응기에서의 입자 마모특성)

  • Moon, Jong-Ho;Lee, Dong-Ho;Ryu, Ho-Jung;Park, Young Cheol;Lee, Jong-Seop;Min, Byoung-Moo;Jin, Gyoung Tae
    • Clean Technology
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    • v.20 no.4
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    • pp.359-366
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    • 2014
  • Attrition characteristics of PKM1-SU particles, $CO_2$ absorbents for pre-combustion $CO_2$ capture process, and FCC particles, catalytic particles for hydro cracking of crude oil, were investigated at high temperature and high pressure conditions. Particle attrition tests were executed at various kinds of temperature ($0-400^{\circ}C$) and pressure (0-20 bar) conditions in a cylinder type bubbling fluidized bed with 15.1 cm diameter, 120 cm height and 1 mm orifice-sparger tube. Attrited particles before and after tests were analyzed by BET, optical microscopy, and particle size analyzer. Effects of bed material height (solid inventory) and steam injection were also verified by using ASTM D5757-95, conventional attrition test method.

Development of Scoring Model on Customer Attrition Probability by Using Data Mining Techniques

  • Han, Sang-Tae;Lee, Seong-Keon;Kang, Hyun-Cheol;Ryu, Dong-Kyun
    • Communications for Statistical Applications and Methods
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    • v.9 no.1
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    • pp.271-280
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    • 2002
  • Recently, many companies have applied data mining techniques to promote competitive power in the field of their business market. In this study, we address how data mining, that is a technique to enable to discover knowledge from a deluge of data, Is used in an executed project in order to support decision making of an enterprise. Also, we develope scoring model on customer attrition probability for automobile-insurance company using data mining techniques. The development of scoring model in domestic insurance is given as an example concretely.

A Study on Lanchester Type Combat Models for Heterogeneous Forces with Terrain Coefficient (지형계수를 고려한 Lanchester형 이질부대 전투모형연구)

  • 신희래;김충영
    • Journal of the military operations research society of Korea
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    • v.26 no.1
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    • pp.1-14
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    • 2000
  • This research studies an attrition rate considering terrain feature in a battlefield. Lanchester-type combat models for heterogeneous forces and the Weapon Effectiveness Index are used in this study. The various environments of the battlefield can be explained by the terrain feature. Attrition rates of heterogeneous model are estimated by applying the battle of Baek-Sek mountain during the Korean War. Estimated attrition rates are checked by the paired samples T-Test. Specific cases are shown in this paper as an example. If we study out the relative influence of the terrain feature upon the performance of individual weapons, these will be a possible alternative to analyze the military operations.

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Attrition milling법에 의해 제조된 PNW-PMN-PZT 세라믹스의 유전 및 압전 특성

  • O, Yeong-Gwang;Ryu, Ju-Hyeon;Yun, Hyeon-Sang;Jeong, Yeong-Ho
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.6-6
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    • 2010
  • In this study, microstructural and piezoelectric characteristics of PNW-PMN-PZT ceramics manufactured using attrition milling method were investigated. Sintering temperature of the ceramics was varied from $980^{\circ}C$ to $1100^{\circ}C$. At the specimen sintered at $1100^{\circ}C$, mechanical quality factor(Qm) and dielectric constant showed the maxinum values of 2,373 and 1438, respectively. At the specimen sintered at $1080^{\circ}C$, electromechanical coupling factot(kp) also showed the maxinum value of 0.524.

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Cultivation Marketing and Effect Measurement for Improving Sale and Retention of Additional Service Product of A Mobile Telephone Company (이동통신사의 부가서비스 상품 판매와 유지 증대를 위한 Cultivation 마케팅과 성과측정)

  • Chun, Heui-Ju
    • Korean Management Science Review
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    • v.26 no.3
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    • pp.11-21
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    • 2009
  • In this paper, we proposed some valuable analysis results of cultivation campaign marketing in A mobile telephone company. The cultivation campaign marketing is a new outbound TM campaign strategy composed of 4 steps for new subscribers. During the analyses, attrition rate of A mobile company, outbound TM rejection rate, contact rate/call success rate and additional service attrition rate after subscription are measured as an effect of cultivation campaign. The results showed that there were no statistical significance in improving retention rate between customers experienced 4 step cultivation campaign and control group. However, the cultivation campaign had a better effect on improving response rate and success of selling additional service product of mobile company compared to general selling campaign. This is because cultivation campaign group had been taking care of from subscription time. It is suggested that cultivation campaign had better confined customers more likely to buy additional service to outbound TM for the sake of financial efficiency.

Effects of Particle Size on Properties of PZT -Based Thick Films (입자 크기가 PZT계 압전 후막의 물성에 미치는 영향)

  • 김동명;김정석;천채일
    • Journal of the Korean Ceramic Society
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    • v.41 no.5
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    • pp.375-380
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    • 2004
  • Pb(Ni$\_$1/3/Nb$\_$2/3/)O$_3$-PbZrO$_3$-PbTiO$_3$ thick films were screen-printed on platinized alumina substrates and fired at 800-1000$^{\circ}C$. Two kinds of powders with different particle size were prepared by attrition and ball milling methods. Effects of particle size of starting material on the microstructure and electrical properties of the thick films were investigated. Average particle size of attrition milled-powder (0.44 ${\mu}$m) was much smaller than that of ball milled-powder (2.87 ${\mu}$m). Average grain size of the thick film prepared from attrition-milled powder was smaller than that of the thick film prepared from ball-milled powder at the sintering temperature of 800$^{\circ}C$. However, the difference in average particle size became smaller with increasing the sintering temperature. Thick films prepared from attrition-milled powders showed more uniform and denser microstructures at all firing temperatures. Thick films prepared from attrition-milled powders had better electrical properties at the firing temperature above 900$^{\circ}C$ than thick films prepared from ball-milled powders. Dielectric constant, remanent polarization and coercive field of the thick film prepared from attrition-milled powders and fired at 900$^{\circ}C$ were 559, 16.3 ${\mu}$C/cm$^2$, and 51.3 kV/cm, respectively.