• Title/Summary/Keyword: reasons of lag

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Effective number of mega-bracing, in order to minimize shear lag

  • Zahiri-Hashemi, Rouzbeh;Kheyroddin, Ali;Farhadi, Basir
    • Structural Engineering and Mechanics
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    • v.48 no.2
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    • pp.173-193
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    • 2013
  • In this paper, influence of geometric configurations of multi-story bracing on shear lag behaviour of braced tube structures is investigated. The shear lag of 24-, 36- and 72-story braced tube structures are assessed considering all possible configurations of overall X and Chevron bracing types. Based on the analytical results, empirical equations, useful for the preliminary design phase, are proposed to provide the optimum number of stories that braced, in order to exert minimum shear lag on structures. Studying the interaction behaviour of a tube and different bracing types along with paying attention to the shear lag behaviour, a better explanation about the reasons behind the efficiency of a specific bracing module in decreasing the shear lag is developed. The analytical results show that there are distinct differences between the anatomy of braced tube structures with X and Chevron bracing regarding the shear lag behaviour.

Tentative Analysis on the Reasons of China's Lags in Neoteric Mathematics

  • Zhang, Xiong
    • Research in Mathematical Education
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    • v.12 no.2
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    • pp.143-149
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    • 2008
  • Before the 14th century, China had been thought as one of the countries with the most developed mathematics all along. But after the 16th century, Chinese mathematics increasingly walked up to the eclipse. The main reasons include the following points. First, the development of neoteric mathematics was closely associated with the social industrialization, but the lags in feudal China seriously blocked the development of the capitalistic seed, and China was still in the agricultural society then and couldn't step into the industrial society, which impeded the development of mathematics concerned with the industry and commerce. Second. the increasingly carrion feudalization was one of the essential reasons to block the development of Chinese neoteric mathematics. Finally, seeing about the developing logics of Chinese neoteric mathematics, we can find it was a scattered and experiential mathematical knowledge without strict and rational self-organizing structure system, which had the limitations existing in its interior mechanism.

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Digital Positioning Control of Pneumatic Cylinder System with Elastic and Viscous Load (탄성 및 점성 부하시 공기압 실린더 시스템의 디지털 위치 제어)

  • 박명관;문영진;편창관
    • Journal of the Korean Society for Precision Engineering
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    • v.15 no.1
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    • pp.137-144
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    • 1998
  • For a model system consisted of four pneumatic cylinders with strokes of 10, 20, 40 and 80 mm, investigation was carried out experimentally and numerically about the reliability of system with elastic and viscous load. The elastic load affects the performance of each cylinder in cylinder series, and changes the time lag and the velocity of the piston which makes the positioning control rather difficult. Taking the effects of the elastic load into consideration, positioning can be carried out comparatively smoothly by only adjusting the driving timing. The effect of a viscous load reduces the vibration of each moving body in the cylinder series and also reduces the over-travelled distance which happens when several cylinders move at the same time. For reasons, a positioning with a viscous load can be relatively smoothly carried out even without the timing control.

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Waste Activated Sludge for Start-up Seed of Thermophilic Anaerobic Digestion (고온 혐기성 소화공정의 start-up seed로서의 호기성 폐 활성슬러지 이용가능성 연구)

  • Kim, Moonil;Shin, Kyuchul
    • Journal of Korean Society on Water Environment
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    • v.21 no.5
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    • pp.490-495
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    • 2005
  • Since there are very limited numbers of thermophilic anaerobic digesters being operated, it is often difficult to start up a new one using sludge from an existing reactor as a seed. However, for obvious reasons it seems few attempts have been made to compare the start-up performance of thermophilic anaerobic digestion using different sources of seed sludges. The purpose of this study was to evaluate the start-up performance of anaerobic digestion using aerobic Waste Activated Sludge (WAS) from a plant and mesophilic Anaerobic Digested Sludge (ADS) as the seed source at both mesophilic ($35^{\circ}C$) and thermophilic ($55^{\circ}C$) temperatures. In this study, two experiments were conducted. First, thermophilic anaerobic reactors were seeded with WAS (VSS = 4,400 mg/L) and ADS (VSS = 14,500 mg/L) to investigate start-up performance with a feed of acetate as well as propionate. The results show that WAS started to produce $CH_4$ soon after acetate feeding without a lag time, while ADS had a lag time of 10 days. When the feed was changed to propionate, WAS removed propionate down to below the detection limit of 10 mg/L, while ADS removed little propionate and produced little $CH_4$. Second, in order to further compare the methanogenic activity of WAS and ADS, both mesophilic and thermophilic reactors were operated. WAS acclimated to anaerobic conditions shortly and after acclimating it produced more $CH_4$ than ADS. WAS at mesophilic temperature biodegraded acetate at the same rate as for thermophilic. However WAS at mesophilic temperature biodegraded propionate at a much faster rate than at thermophilic. WAS as the seed source of anaerobic digestion resulted in much better performance than ADS at both mesophilic and thermophilic temperatures for both acetate and propionate metabolism.

Detection of Fire Location And Reliability Improvement of the Conventional Fire Detector and P-type Receiver (재래식 화재감지기와 P형 수신기에 대한 화재위치검출 및 신뢰성 개선)

  • Jee, Seung-Wook;Kim, Shi-Kuk;Yang, Seung-Hyun;Lee, Jae-Jin;Kim, Pil-Young;Lee, Chun-Ha
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.25 no.5
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    • pp.39-44
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    • 2011
  • Automatic fire alarm system is set up to automatically detect fire on buildings. Because of economic reasons, P-type receiver and a conventional type fire detector is normally used for automatic fire alarm system in Korea. Because early detection of fire is regarded as important, the need of finding technique of fire location increases. This paper is studied a method to improve a reliability and add a function of fire location detection on a conventional type fire detector and P-type receiver. Fire location is detected by a method that controller attached on the receiver and the detector is read with a time lag. A reliability of fire detection alarm system is improved with a method that false fire alarm is able to decrease using two different principle detector together. This paper is studied for basic data of improvement of low-cost addressable automatic fire alarm system.

Degradation characteristics in anaerobic co-digestion of sewage sludge and food waste (하수슬러지와 음식물쓰레기의 혼합소화시 혼합비율과 기질농도에 따른 분해특성)

  • Shin, Hang-Sik;Kim, Hyun-Woo;Han, Sun-Kee;Kang, Seok-Tae
    • Journal of the Korea Organic Resources Recycling Association
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    • v.10 no.1
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    • pp.96-101
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    • 2002
  • This research was conducted to find the optimal condition in codigestion of food waste and sewage sludge with various mixing ratios. The analysis of degradation characteristics were based on the variations of methane production as well as methane production rate (MPR). BMP values were getting higher as the addition of foodwaste increased. But the lag-phase were prolonged when the foodwaste was over 40%, Nonlinear regression was conducted with the cumulative methane production data. Not only thermophilic but mesophilic condition, 40% of foodwaste addition showed maximum MPR. Higher mixing ratio which is over 50% were unprofitable in gaining higher MPR values. The most important factor in thermophilic co-digestion was substrate concentration. But in mesophilic co-digestion, both substrate concentration the mixing ratio had major effects on MPR. The most probable reasons of the synergetic effects in co-digestion of foodwaste and sewage sludge were the balanced nutrient expressed as C/N ratio and increased kinetic constants of hydrolysis by the mixed co-substrates.

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Artifacts in Digital Radiography (디지털 방사선 시스템에서 발생하는 Artifact)

  • Min, Jung-Whan;Kim, Jung-Min;Jeong, Hoi-Woun
    • Journal of radiological science and technology
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    • v.38 no.4
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    • pp.375-381
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    • 2015
  • Digital Radiography is a big part of diagnostic radiology. Because uncorrected digital radiography image supported false effect of Patient's health care. We must be manage the correct digital radiography image. Thus, the artifact images can have effect to make a wrong diagnosis. We report types of occurrence by analyzing the artifacts that occurs in digital radiography system. We had collected the artifacts occurred in digital radiography system of general hospital from 2007 to 2014. The collected data had analyzed and then had categorize as the occurred causes. The artifacts could be categorized by hardware artifacts, software artifacts, operating errors, system artifacts, and others. Hardware artifact from a Ghost artifact that is caused by lag effect occurred most frequently. The others cases are the artifacts caused by RF noise and foreign body in equipments. Software artifacts are many different types of reasons. The uncorrected processing artifacts and the image processing error artifacts occurred most frequently. Exposure data recognize (EDR) error artifacts, the processing error of commissural line, and etc., the software artifacts were caused by various reasons. Operating artifacts were caused when the user didn't have the full understanding of the digital medical image system. System artifacts had appeared the error due to DICOM header information and the compression algorithm. The obvious artifacts should be re-examined, and it could result in increasing the exposure dose of the patient. The unclear artifact leads to a wrong diagnosis and added examination. The ability to correctly determine artifact are required. We have to reduce the artifact occurrences by understanding its characteristic and providing sustainable education as well as the maintenance of the equipments.

Measuring the Coverage of Book Collection in the National Library of Korea (국가장서 포괄성 측정 연구: 판매도서를 대상으로)

  • Chang, Hye-Rhan;Hong, Hyun-Jin;Noh, Young-hee;Oh, Eui-Kyung
    • Journal of the Korean Society for information Management
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    • v.26 no.4
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    • pp.187-200
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    • 2009
  • The purpose of the national library is to collect all publications as part of the national heritage and preserve them. This study is undertaken to determine the coverage of the book collection of the National Library of Korea. Bibliographies for the year 2007 and 2008 publications are obtained from the Kyobo Book Centre and sampled 10 % systematically to be used as checklists. Coverage was determined by searching the citations against the OPAC of the National Library of Korea. Results indicate 92.25% of coverage for the books published in 2008, 78.10% coverage for the books published in 2007, and the cumulative coverage is 85.16%. The analysis shows time lag and subject fields with low coverage. Results are compared with previous studies. Reasons for the unpossessed books, such as delay of deposit and publisher characteristics, are identified. Recommendations for the coverage improvements and future research are suggested.

What Shall We Do for the Academic Information Systems Sustainability?: The Role of Mindfulness (지속 가능한 대학 경쟁력의 원천: 마을챙김의 대학 정보화)

  • Kim, Yong-Young;Ahn, Joong-Ho;Oh, Sang-Jo
    • Information Systems Review
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    • v.11 no.2
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    • pp.1-22
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    • 2009
  • IT advances rapidly and is widely used both in for-profit and non-profit organizations. Academic institutions are no exception in the adoption of new IT such as e-libraries, e-blackboards, as well as Web 2.0 services. However, administrative information systems in colleges and universities often lag relatively behind. One of the reasons of this is that academic institutions tend to focus only on the implementation of IT, while neglecting the mindfulness needed for post-implementation. This study develops a new perspective for the sustainability of academic information systems through the lens of mindfulness. The results from administrating a nation-wide survey of universities and colleges provide the variations of a ranking of the critical success factors between implementation and post-implementation. The findings imply that both individual and collective mindfulness are needed to implement and, especially, sustain administrative IS successfully in academic institutions.

A Study on Industries's Leading at the Stock Market in Korea - Gradual Diffusion of Information and Cross-Asset Return Predictability- (산업의 주식시장 선행성에 관한 실증분석 - 자산간 수익률 예측 가능성 -)

  • Kim Jong-Kwon
    • Proceedings of the Safety Management and Science Conference
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    • 2004.11a
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    • pp.355-380
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    • 2004
  • I test the hypothesis that the gradual diffusion of information across asset markets leads to cross-asset return predictability in Korea. Using thirty-six industry portfolios and the broad market index as our test assets, I establish several key results. First, a number of industries such as semiconductor, electronics, metal, and petroleum lead the stock market by up to one month. In contrast, the market, which is widely followed, only leads a few industries. Importantly, an industry's ability to lead the market is correlated with its propensity to forecast various indicators of economic activity such as industrial production growth. Consistent with our hypothesis, these findings indicate that the market reacts with a delay to information in industry returns about its fundamentals because information diffuses only gradually across asset markets. Traditional theories of asset pricing assume that investors have unlimited information-processing capacity. However, this assumption does not hold for many traders, even the most sophisticated ones. Many economists recognize that investors are better characterized as being only boundedly rational(see Shiller(2000), Sims(2201)). Even from casual observation, few traders can pay attention to all sources of information much less understand their impact on the prices of assets that they trade. Indeed, a large literature in psychology documents the extent to which even attention is a precious cognitive resource(see, eg., Kahneman(1973), Nisbett and Ross(1980), Fiske and Taylor(1991)). A number of papers have explored the implications of limited information- processing capacity for asset prices. I will review this literature in Section II. For instance, Merton(1987) develops a static model of multiple stocks in which investors only have information about a limited number of stocks and only trade those that they have information about. Related models of limited market participation include brennan(1975) and Allen and Gale(1994). As a result, stocks that are less recognized by investors have a smaller investor base(neglected stocks) and trade at a greater discount because of limited risk sharing. More recently, Hong and Stein(1999) develop a dynamic model of a single asset in which information gradually diffuses across the investment public and investors are unable to perform the rational expectations trick of extracting information from prices. Hong and Stein(1999). My hypothesis is that the gradual diffusion of information across asset markets leads to cross-asset return predictability. This hypothesis relies on two key assumptions. The first is that valuable information that originates in one asset reaches investors in other markets only with a lag, i.e. news travels slowly across markets. The second assumption is that because of limited information-processing capacity, many (though not necessarily all) investors may not pay attention or be able to extract the information from the asset prices of markets that they do not participate in. These two assumptions taken together leads to cross-asset return predictability. My hypothesis would appear to be a very plausible one for a few reasons. To begin with, as pointed out by Merton(1987) and the subsequent literature on segmented markets and limited market participation, few investors trade all assets. Put another way, limited participation is a pervasive feature of financial markets. Indeed, even among equity money managers, there is specialization along industries such as sector or market timing funds. Some reasons for this limited market participation include tax, regulatory or liquidity constraints. More plausibly, investors have to specialize because they have their hands full trying to understand the markets that they do participate in

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