• 제목/요약/키워드: Negative Flow Control

검색결과 115건 처리시간 0.022초

Integrated Environment Impact Assessment of Brick Kiln using Environmental Performance Scores

  • Pokhrel, Rajib;Lee, Heekwan
    • Asian Journal of Atmospheric Environment
    • /
    • 제8권1호
    • /
    • pp.15-24
    • /
    • 2014
  • The capital city of Himalayan Country Nepal, Kathmandu Valley is surrounded by consecutive high mountains, which limits the air distribution and mixing effects significantly. It in turn generates steady air flow pattern over a year except in monsoon season. The air shed in the Valley is easily trapped by the surrounded mountains and the inversion layer formulated as the cap. The $PM_{10}$ concentration was noticeably higher than the standard level (120 ${\mu}g/m^3$) in urban and suburban area of Kathmandu valley for all seasons except monsoon period. The Valley area experiences similar wind patterns (W, WWS, and S) for a year but the Easterly wind prevails only during the monsoon period. There was low and calm wind blows during the winter season. Because of this air flow structure, the air emission from various sources is accumulated within the valley air, high level of air pollution is frequently recorded with other air polluted cities over the world. In this Valley area, brick kilns are recognized as the major air pollution source followed by vehicles. Mostly Bull Trench Kiln (BKT), Hoffman Kiln and Vertical Shaft Brick Kiln (VSBK) are in operation for brick firing in Kathmandu valley where the fuels such as crushed coal, saw dust, and natural gas are used for processing bricks in this study. Tool for the Reduction and Assessment of Chemical and Other Environmental Impacts (TRACI) was used for screening and quantifying the potential impacts of air emission from firing fuels. The total Environmental Performance Score (EPS) was estimated and the EPS of coal was approximately 2.5 times higher than those of natural gas and saw dust. It is concluded that the crushed coal has more negative impact to the environment and human health than other fuel sources. Concerning the human health and environment point of view, alternative environment friendly firing fuel need to be used for brick industry in the kiln and the air pollution control devices also need to be applied for minimizing the air emissions from the kilns.

물과 성찰(省察) (WATER AND INTROSPECTION)

  • 신성웅;조수철
    • Journal of the Korean Academy of Child and Adolescent Psychiatry
    • /
    • 제12권1호
    • /
    • pp.3-24
    • /
    • 2001
  • All human being can't exist by oneself. That is, all human being depend on intimate attachment for their survival. Physical and psychological powers and control functions are prerequisites for one's survival and these serve important functions in interpersonal relationships. There are two kinds of powers and controls. One is positive power which helps one survive effectively. Another one is negative power which disturbs one's effective survival. Introspection is one of the positive power and most important process in understanding oneself and others. Thus, the purpose of this study is to elucidate the physical and psychological meaning of the characteristics of water and based on this meaning, to suggest one way of introspection. The authors reviewed the precept of water which is described in Bible and oriental classical books such as 'the Analects of Confuicus(論語)', 'Tao Te Ching(道德經)', 'Mencius(맹자)', 'Chronicle(史記)', 'The Doctrine of the Mean(中庸)', 'University(大學)'. The author also reviewed 'The History of Three Countries(삼국사기, 삼국유사)', 'The Precept of Religion', and 'the modern poems' which includes the symbolic meaning of water. The results are summarized as follows:1) The flow of water itself is the expression of introspection. Because, water does not flow without filling a puddle. 2) Water is the symbol of 'Immortality'. 3) Water symbolizes 'Modesty and Trust'. 4) Water is the symbol of 'Freedom from Greed'. 5) Water symbolizes 'Goodness and Beauty'. 6) Water symbolizes 'Naturality and Love'. Immortality, Modesty and Trust, Freedom from Greed, Goodness and Beauty, and Naturality and Love are eternal, universal values which all human should seek and achieve. By the process of introspection through the symbolic meaning of water, we can achieve these positive aspects of human mind and spirit.

  • PDF

Blue dam을 활용한 기존 댐 시설물 상수도 원수 추가 확보 방안 (The method of securing water supply resources of existing dam by using Blue dam)

  • 추태호;윤현철;윤관선;권용빈;심수용;채수권
    • 상하수도학회지
    • /
    • 제29권2호
    • /
    • pp.243-249
    • /
    • 2015
  • To improve stability of the water resources that were seriously affected by climate change and various environmental effects and to supply the clean water always, continuous efforts are essential. Provision of measures with respect of hardware is basically essential to improve the water resources stability due to the topographic characteristic in Korea. However, building a new dam becomes gradually very difficult because of a hardship in selecting right places, opposition forces such as environment and local residents, negative publicity for large civil engineering projects, and so on. The present study, therefore, proposes the Blue dam as an alternative for securing the water resources of a new concept considering domestic conditions. To evaluate the effect of the Blue dam, the Hec-ResSim model is used and the probabilistic discharge flow rate is applied. As a result, when Dam Yeongcheon is applied as a study area, securing water resources of 14 million tons are predicted be secured and the flood control of 15.4 million tons is expected, in comparison with operation of the existing dam only. Consequently, Blue dams are supposed to carry out the function of securing water resources, controling flood, maintaining eco-environmental instream flow, generating hydroelectric power, and providing spaces for recreational activities.

실물옵션을 이용한 신재생에너지 R&D의 경제적 가치 및 최적 적용시점 평가 (Evaluation of the Economic Values and Optimal Deployment Timing of R&D Investment in New and Renewable Energy Using Real Option Approach)

  • 김경택;이덕주;박성준
    • 대한산업공학회지
    • /
    • 제38권2호
    • /
    • pp.144-156
    • /
    • 2012
  • In recent years, advanced countries in energy sector are emphasizing the importance of the development and deployment of renewable energy to cope with the global environmental crisis such as depletion of fossil energy, climate convention to control emissions of greenhouse gases. In this paper, we evaluate the economic value of the investment in new and renewable energy R&D in Korea and optimal deployment timing of new and renewable energy by using the real option approach. The real option model adopted in this paper assumes that a decision maker has a compound option to abandon, deployment, or continue the R&D. As a result by using empirical data of Korea, it is found that there exists a considerable amount of positive real option value (ROV) in the investment of new and renewable energy R&D while its net present value (NPV) calculated by traditional discounted cash flow (DCF) model shows negative value.

토끼의 신장기능에 미치는 $K^+$ Channel 차단제인 Glibenclamide의 영향 (Effect of Glibenclamide, $K^+$ Channel Blocker, on Renal Function in Rabbit)

  • 고석태;나종학
    • Biomolecules & Therapeutics
    • /
    • 제9권1호
    • /
    • pp.26-32
    • /
    • 2001
  • This study was investigated about the effect of glibenclamide (GLY) which is $K^{+}$ channel blocker on renal function in rabbit, GLY, when given into the vein, produced the diuretic action accompanied with the increases of amounts of N $a^{+}$ and $K^{+}$ excreted into urine ( $E_{Na}$ , $E^{K}$), and then osmolar and negative free water clearances ( $C_{osm}$, $T^{C}$$_{H2O}$), fraction excretory rates of filtered N $a^{+}$ and $K^{+}$ ( $F_{Na}$ , $F_{K}$) and ratios of $E_{K}$ against $E_{Na}$ were augmented. Filtration fraction (FF) were reduced because renal plasma flow (RPF) were not changed but glomerular filtration rates (GFR) were diminished. GLY administered into a renal artery exhibited significant reduction of urine volume along with the decreases of GFR and RPF in only experimented kidney whereas changes of renal function was not observed in control kidney. GLY given intracerebroventricularly exhibited diuretic action along with the increase of $E_{Na}$ , $E_{K}$ and $F_{Na}$ , $F_{K}$ by small dose which was not affect on renal function when it given into the vein. Above results suggest that GLY given into the vein in rabbit produce the diuretic action by inhibition of electrolytes reabsorption in renal tubules through central function. function.n. function.ion.

  • PDF

화자의 긍정·부정 의도를 전달하는 실용적 텔레프레즌스 로봇 시스템의 개발 (Development of a Cost-Effective Tele-Robot System Delivering Speaker's Affirmative and Negative Intentions)

  • 진용규;유수정;조혜경
    • 로봇학회논문지
    • /
    • 제10권3호
    • /
    • pp.171-177
    • /
    • 2015
  • A telerobot offers a more engaging and enjoyable interaction with people at a distance by communicating via audio, video, expressive gestures, body pose and proxemics. To provide its potential benefits at a reasonable cost, this paper presents a telepresence robot system for video communication which can deliver speaker's head motion through its display stanchion. Head gestures such as nodding and head-shaking can give crucial information during conversation. We also can assume a speaker's eye-gaze, which is known as one of the key non-verbal signals for interaction, from his/her head pose. In order to develop an efficient head tracking method, a 3D cylinder-like head model is employed and the Harris corner detector is combined with the Lucas-Kanade optical flow that is known to be suitable for extracting 3D motion information of the model. Especially, a skin color-based face detection algorithm is proposed to achieve robust performance upon variant directions while maintaining reasonable computational cost. The performance of the proposed head tracking algorithm is verified through the experiments using BU's standard data sets. A design of robot platform is also described as well as the design of supporting systems such as video transmission and robot control interfaces.

돈사용 환기팬을 위한 돈사 내 온도 분포 특성 (Characteristics of Temperature Distribution of Pen for Exhaust Fan of Ventilation System)

  • 김현태;김웅
    • 한국축산시설환경학회지
    • /
    • 제20권4호
    • /
    • pp.155-160
    • /
    • 2014
  • This study was researched for use by data for the improvement of ventilation system of optimum environmental control systems. The ventilation system for windowless swine housing was installed negative pressure system that circular pipe duct for inlet was installed on the ceiling and axial flow fan for exhaust was installed on the sidewall. The temperatures in the pen was measured using infrared thermography camera and thermocouple with data-logger. The temperature measurement points was selected by infrared thermography camera is alley (G), inlet (A), front-upper (B), front-lower (C), rear-upper (D), rear-lower (E), forward fan (F). The temperature measured at those selected points for temperature distribution was $28^{\circ}C$ that was maintained setting temperature in suitably. The temperature deviations of F point and A~E points in windowless swine housing was less then average $0.5^{\circ}C$. The result of air velocity of measured points was suitable to the breeding of pigs.

변형 공간벡터 변조 기법이 적용된 Bq-ZSI를 이용한 유도전동기 구동시스템 (Bq-ZSI fed Induction Motor Drive System Using Modified Space Vector Modulation)

  • 한상협;김흥근;차헌녕;전태원;노의철
    • 전력전자학회논문지
    • /
    • 제23권1호
    • /
    • pp.9-15
    • /
    • 2018
  • This study investigates a bidirectional quasi-Z-source inverter (Bq-ZSI) system with bidirectional power transfer capability and a modified space vector modulation scheme for reducing the ripple of the inductor current. By replacing the diode in the impedance network with an active switch, the power flow can be bidirectional. The average inductor current of the Bq-ZSI network is negative in the regenerative braking mode, thereby regenerating the power. In addition, modified space vector modulation scheme is applied to the Bq-ZSI to control shoot-through time effectively. A 5 kW prototype is built and tested to implement the proposed system. Experimental results show that the Bq-ZSI system is capable of regenerative braking of the induction motor and that the modified space vector modulation method is efficient.

The Influence of the Debt Ratio and Enterprise Performance of Joint Stock Companies of Vietnam National Coal and Mineral Industries Holding Corp.

  • HOANG, Thi Thuy;HOANG, Lien Thi;PHI, Thi KimThu;NGUYEN, Minh Thu;PHAN, Minh Quang
    • The Journal of Asian Finance, Economics and Business
    • /
    • 제7권10호
    • /
    • pp.803-810
    • /
    • 2020
  • This objective of this study is to enrich the literature by the debt ratio and enterprise performance of Joint stock companies of Vietnam National Coal and Mineral Industries Holding Corporation Limited (Vinacomin). The debt ratio is an important index of capital structure, and it influences and decides the enterprise performance. Therefore, the determination of reasonable debt ratio level is beneficial to the stable operation of Vinacomin's enterprises. Based on the research conclusion about the effect on capital structure of debt ratio from domestic and foreign scholar, collecting data from 2014-2018 of Vinacomin's enterprises as a research sample, the article conducts research on the relationship between debt ratio and business performance of Vinacomin, as measured by return on total Assets. In addition, the study uses free cash flow, company size, growth opportunity, investment opportunities, operating costs to sales ratio as control variables.The study shows the debt ratio of Joint stock companies of Vietnam National Coal and Mineral Industries Holding Corporation Limited has a negative effect on the enterprise performance. Furthermore, the research results of the article are references for Vinacomin' enterprises in the course of production and business activities, determining a reasonable debt ratio, and improving the operational performance of enterprises.

Donor Country's Fiscal Status and ODA Decisions before and after 2008 Global Financial Crisis

  • Ahn, Hyeonmi;Park, Danbee
    • 산경연구논집
    • /
    • 제9권1호
    • /
    • pp.25-38
    • /
    • 2018
  • Purpose - The purpose of this study is to empirically investigate the impact of donor's fiscal status on aid decisions before and after the 2008 global financial crisis. The effects on aid can change depending on the donor country's fiscal status and the period of financial crisis. Research design, data, and methodology - A fixed effect regression and dynamic panel GMM is conducted using a comprehensive dataset combining 31 donor and 167 recipient countries during 1996-2015. The key explanatory variable is central government debt-to-GDP ratio of donor country. Recipient countries' GNI per capita, population, governance indicators, and bilateral trade-to-GDP ratio between donor and recipient countries are included as control variables. Results - We can confirm the relationship between donor country's fiscal status and aid flow. The cyclical component of government debt is found to have a negative impact on grant decisions particularly after the 2008 global financial crisis. This effect becomes larger in the countries with high government debt-to-GDP ratio. ODA decisions from the countries with low financial constraint do not significantly affected by the recipient countries' factors such as GNI, population, and governance indicator. Conclusions - Based on the empirical results of this study, the source of aid should be diversified by incorporating private sector and innovative financing sources.