• Title, Summary, Keyword: attrition

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A Study of Optimal Aircraft Allocation Model for Attacking Fixed Target (고정목표 공격을 위한 최적 항공기 할당모형에 관한 연구)

  • Heo Jong-Jun;Kim Chung-Yeong
    • Journal of the military operations research society of Korea
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    • v.12 no.2
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    • pp.22-36
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    • 1986
  • The study is to design optimal aircraft allocation model for sufficing the required level of damage, minimizing attrition cost when the aircrafts attack the enemy's fixed target. When friendly aircraft attacks enemy target, the aircraft will suffer the loss due to the enemy's anti-aircraft weapons and aircraft. For this study, it is required that the probability of target damage by the type of aircraft, level of target damage and attrition cost are computed for the application of this model.

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Development and Evaluation of the Attrition Coupled Bioreactors for Enzymatic Hydrolysis of Biomass ; Tumbling-Drum Type Bioreactor for Enzymatic Hydrolysis of Cellulose (Biomass의 고효율 효소당화에 적합한 Attrition Coupled Bioreactor 개발에 관한 연구 ; Tumbling Drum Type Bioreactor를 활용한 섬유소 당화)

  • 이용현;조구형;박진서
    • KSBB Journal
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    • v.4 no.2
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    • pp.87-93
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    • 1989
  • To develop high dfficiency-low energy consumption attrition coupled bioreactor for enhanced enzymatic hyerolysis of insoluble biomass, a tumbling drum type bioreactor was installed, and its efficiency was evaluated. The effects of drum structure and poerational conditions were investigated. The optimal saccharification at 3L drum was obtained at 8 baffled drum, drum diameter to baffle height ratio of 1:0.05, 100rpm, and addition of 600g of 3mm glass bead per liter. The consumed power for rolling of drum and energy consumption for half digestion of cellulose were measured, and compared with enhanced rate and yield to predict the economic prospect of the process. The tumbling drum type bioreactor seems to have appropriated structure for industrial scale operation, and further investigation for scale-up need to be conducted.

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Development and Evaluation of the Attrition Coupled Bioreactors for Enzymatic Hydrolysis of Biomass ; Horizontal Paddle Type Bioreactor for Enzymatic Hydrolysis of Cellulose (Biomass의 고효율 효소당화에 적합한 Attrition Coupled Bioreactor 개발에 관한 연구;Horizontal Paddle Type Bioreactor를 활용한 섬유소 당화)

  • 이용현;박진서
    • KSBB Journal
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    • v.4 no.3
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    • pp.215-220
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    • 1989
  • To develop an attrition coupled enzyme reactor with high efficiency-low energy consumption for saccharification of insoluble biomass, a 5L horizontal paddle type bioreactor was constructed and its performance was evaluated. The optimal condition for saccharification of 50g $\alpha$ -cellulose/L was found to be 200rpm with 500g of 3mm glass bead. Especially, the horizontal paddle type bloreactor was very effective for saccharification of high concentration of insoluble cellulose, in which around 72% of $\alpha$ -cellulose was saccharified for 75g $\alpha$ -cellulose/L, and even up to 70% for 100g of $\alpha$ -cellulose/L after 24hours. Under the optimal condition, the power consumption was measured to be around 1.7watth/g. Horizontal paddle type bioreactor seems to have an appropriated structural feature for industrial scale operation and to be an effective and energy saving attrition coupled enzyme reactor.

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Evaluation of Operational Conditions and Power Consumption of a Bioattritor for Enzymatic Saccharification of Uncooked Starch (무증자 전분당화용 분쇄마찰매체 함유 효소반응기의 조작조건과 동력소모의 검토)

  • 이용현;박진서
    • Microbiology and Biotechnology Letters
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    • v.17 no.4
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    • pp.349-357
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    • 1989
  • Uncooked starch can be effectively saccharified in an enzyme reaction system containing attrition-milling media. To develope the high efficiency bioattritor, an agitated bead type bioreactor was constructed, and its effectiveness was evaluated. The optimal operation condition of bioattritor was found to be 300 g glass bead/L, 200 rpm, standard type impeller for 220 g/L of uncooked corn starch. The torque under the various operational conditions were also measured. The interrelation-ship between energy consumption for agitation of attrition-milling media and enhanced extent of saccharification of uncooked starch was evaluated, Power consumption was measured to be around 1.53 watt/L under the optimal operation condition. The attrition coupled enzyme reaction system is identified to tie a very excellent energy saying process for saccharification of uncooked starch, and seems to have a bright prospect of industrial application.

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Alternative Policy on Attrition Propensities of Travel Voucher (여행바우처 이탈에 관한 정책적 대안 연구)

  • Han, Suk Young;Park, Sang Gon;Jun, Minji
    • The Journal of the Korea Contents Association
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    • v.17 no.9
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    • pp.486-497
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    • 2017
  • Travel voucher for low-income or social disadvantaged groups forms a part of social policies in Korea. The policy can not only provide an opportunity of travel experiences for the socially weak, but also enhance their family capital and social capital. Thus, the travel voucher policy can be beneficial for the participants and their society. However, little research evidence of its evaluation and challenges/benefits exists. In practice, one of the biggest problems is an attrition of travel voucher winners which is to decrease a cost-effect of the travel voucher policy and to increase unnecessary waste of both the federal and human resources. Thus more research is needed to answer the questions why some of winners abandon to go to travel by the voucher, and who is the seceder? In this context, the study empirically examines the attrition propensity for the winners of 2011 Seoul travel voucher from 1,632 respondents and second data from Korea Tourism Organization. This research found that total education years of travel voucher winners have a significant effect on using their voucher. Implications and alternative policies for government policy makers and administrators are discussed by the analyzed results.

Impact of Panel Attrition and Conditioning : The Case of KBS-MBMR's 2007 Korean Presidential Election Panel Survey (패널 이탈과 조건화의 영향: KBS-MBMR의 2007년 대통령 선거 패널조사 사례)

  • Huh, Myung-Hoe;Kim, Jee-Yeon;Lee, Ryang-Hoon
    • Survey Research
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    • v.10 no.1
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    • pp.73-89
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    • 2009
  • Even though panel surveys are very useful in estimating the change between time points, they suffer from sample distortion as survey rounds proceed due to panel attrition and conditioning. This study is to report the statistical aspects of KBS-MBMR's five-rounds panel survey for the 2007 Presidential Election of Korea. Main findings are as follows. First, the attrition propensities were higher among women, among the young and the old aged, and among "None"/"Don't Know"/"Won't Say"(DK) respondents for the question asking preferred candidate. Second, there existed the conditioning effect that pushes the respondents to choose one candidate in hurry. Third. repeated measurements of the survey did not influence panel respondents on the choice of preferred candidate. if DK respondents are set. aside, and on the final voting intention of panel respondents.

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Piezoelectric properties and microstructure of 0.01Pb(Mg1/2W1/2)O3-0.41Pb(Ni1/3Nb2/3)O3-0.35PbTiO3-0.23PbZrO3thick film with particle size distribution (입자 크기 분포에 따른 0.01Pb(Mg1/2W1/2)O3-0.41Pb(Ni1/3Nb2/3)O3-0.35PbTiO3-0.23PbZrO3 후막의 미세구조 및 압전특성)

  • Moon, Hi-Gyu;Song, Hyun-Cheol;Kim, Sang-Jong;Choi, Ji-Won;Kang, Chong-Yun;Yoon, Seok-Jin
    • Journal of Sensor Science and Technology
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    • v.17 no.6
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    • pp.418-424
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    • 2008
  • The PZT based piezoelectric thick films prepared by screen printing method have been mainly used as a functional material for MEMS applications due to their compatibility of MEMS process. However the screen printed thick films generally reveal poor electrical and mechanical properties because of their porous microstructure. To improve microstructure we mixed attrition milled powder with ball milled powder of 0.01Pb$(Mg_{1/2}W_{1/2})O_3$-0.41Pb$(Ni_{1/3}Nb_{2/3})O_3$-$0.35PbTiO_3$-$0.23PbZrO_3$+0.1 wt% ${Y_2}{O_3}$+1.5 wt% ZnO composition. By mixing 25 % of attrition milled powder and 75 % of ball milled powder, the broadest particle size distribution was obtained, leading to a dense thick film with crack-free microstructure and improved dielectric properties. The X-ray diffraction analysis revealed that the film was in wellcrystallized perovskite phase. The remanent polarization was increased from $13.7{\mu}C/cm^2$ to $23.3{\mu}C/cm^2$ at the addition of 25 % attrition milled powder.

The effect of Attrition milling and calcining temperature on the microstructure and electrical properties of non-reduction PTCR-$BaTiO_3$ Ceramics (내환원 $BaTiO_3$ 세라믹스의 PTCR특성 및 미세구조에 대한 Attrition milling과 하소온도가 미치는 영향)

  • Lee, Jeong-Cheol;Myoung, Seong-Jae;Chun, Myoung-Pyo;Cho, Jeong-Ho;Kim, Byung-Ik;Sin, Dong-Wook
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.288-288
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    • 2007
  • 본 연구에서 내환원성 $BaTiO_3$의 PTCR(Positive Temperation Coefficient Resistance) 특성 및 미세구조에 대한 분쇄 및 출발 원료들의 하소 조건의 영향을 연구하였다. $BaCO_3$, $TiO_2$, $CeO_2$를 Attrition milling 하여 1차 혼합 및 분쇄한 후 건조하여 혼합분말을 얻었으며, $(Ba_{1-x}Ce_x)TiO_3$를 합성하기 위하여 $1000^{\circ}C{\sim}1200^{\circ}C$ 공기중에서 하소하였다. 각 하소온도에서 제조한 $(Ba_{1-x}Ce_x)TiO_3$에 첨가제를 2차 혼합하고 초미분쇄하여 분말을 제조하였다. 직경 5mm 의 시편을 제조하여 환원 및 재산화 분위기에서 소결을 한 후 상온저항값 및 R-T특성을 측정하였고 SEM 을 통해 미세구조를 관찰하였다. 또한 하소 후 온도에 따른 상분석을 XRD를 통하여 분석하였다. 그 결과 하소온도가 증가함에 따라 상온저항값은 감소하는 경황을 보였으며 PTC특성은 감소하다가 증가하는 경향을 보였다. 초미분쇄에 따른 입자크기는 $1{\mu}m$이하로 작아졌으며 미립화가 됨에 따라 하소/소결온도에 앙향을 줄 것으로 사료된다.

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Recycling of Separate Glass Fiber from Waste Printed Circuit Boards Using Attrition Mill and DMF (어트리션 밀과 DMF 용매를 이용한 폐 인쇄회로기판에서 분리된 재생 유리섬유의 재활용)

  • Kim, Jong-Seok;Lee, Jae-Cheon;Jeong, Jin-Ki
    • Korean Chemical Engineering Research
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    • v.50 no.5
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    • pp.894-899
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    • 2012
  • In recent years, recycling process has come to be necessary for separating metals, glass fibers and polymer from WPCBs (waste printed circuit boards) due to an increasing amount of electronic device waste. In this study, dimethylformamide (DMF) and attrition mill reactor were used to separate the component such as metals, glass fiber and epoxy resin from WPCBs. Separation of glass fiber from WPCBs was carried out under stirring rates 300~600 revolution per minute (rpm) for 1~2 h as the various agitator. The recycled glass fibers (RGF) were analyzed by thermogravimetric analyzer (TGA) for degree of separation of epoxy resin in the WPCBs. The degree of separation of epoxy resin of WPCBs increased in attrition mill agitator as a mechanochemical process for recycling WPCBs. The RGF separated in the WPCBs was applied as a reinforcement in the RGF/unsaturated polyester composites to reuse as a reinforcement.

A STUDY ON THE ATTRITION OF MAXILLARY CENTRAL INCISORS IN KOREAN (한국인 상악중절치의 교모에 관한 연구)

  • Park, Chong-Wha
    • The Journal of Korean Academy of Prosthodontics
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    • v.16 no.1
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    • pp.32-37
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    • 1978
  • The purpose of this study was to apply the position, the form and the angle of the attrition in the natural maxillary central incisors shown on the labial surface to the artificial teeth in the field of prosthetic dentistry. So we should exactly alter the molds of artificial teeth in individual cases in order to make artificial teeth more natural. 226 extracted teeth of the maxillary central incisors were chosen as materials. I have exactly examined the teeth with a magnifying glass and a circular graduator under concentrated light. The observation brought me the following results: 1) The attrition was most prevailing at the range from the mesial angle to the middle part of cutting edge in the left maxillary central incisor, and distal angle of cutting edge in the right maxillary central incisor. 2) On the attrite form of both angles, the angulated form was more than 4 times as frequent as rounded form in the mesial angle, and almost equal in the distal angle. 3) On the attrite form of cutting edge, mesial attrite form including mesial angle was most frequent in the left maxillary central incisor, and distal attrite form including distal angle in the right maxillary central incisor. 4) The angle made by the labial surface and the attrite surface was about $39^{\circ}$, and more than 70% of the total examined teeth were included at the range from $31^{\circ}\;to\;50^{\circ}$. 5) None attrite form at the cutting edge was about 12% and completely attrite form at the cutting edge was about 27% of examined teeth.

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