• Title/Summary/Keyword: Variation rate

Search Result 4,155, Processing Time 0.035 seconds

A Study on Regression Rate in End-Burning Hybrid rocket with Variation of Swirl Intensity (End-Burning 하이브리드 로켓의 스월 강도 변화에 따른 연료 후퇴율에 관한 연구)

  • Choi, Won-Jun;Woo, Kyoung-Jin;Moon, Hee-Jang;Sung, Hong-Gye;Kim, Jin-Kon
    • Proceedings of the Korean Society of Propulsion Engineers Conference
    • /
    • 2012.05a
    • /
    • pp.70-75
    • /
    • 2012
  • In this paper, the regression rate of the End-Burning Hybrid Rocket with variation of swirl intensity was investigated experimentally with the variation of fuel diameter, injector shape and angle. When fuel grain diameter is large, fuel mass flow rate increases. And the injector diameter increase, fuel regression rate decrease. The impinging effect of oxidizer flow on fuel surface for fuel combustion efficiency is stronger than swril effect in this End-burning propulsion system. The relation between the regression rate, oxidizer mass flux and swirl intensity was obtained.

  • PDF

Influence of Seasonal Variation on Basal Metabolic Rates on Thermal Environments & Clothing Weight (생활환경온도와 착의량이 기초대사에 미치는 영향)

  • 이원자;침규남;김진선;박승순
    • The Research Journal of the Costume Culture
    • /
    • v.8 no.3
    • /
    • pp.374-386
    • /
    • 2000
  • This study investigated the relation between seasonal variation of total clothing weight, room, outdoor temperature and basal metabolic rate in man. The basal metabolic rate and total clothing weight, room temperature was determined seasonal for a period of two years and grouped four seasons. Subjects (adults volunteers) who live in seoul and mokpo were compose 120 subject The results were obtained as follows. Seasonal outdoor temperature was difference of seoul and. mokpo. But room temperature in apartments was a little difference than private house. Total-clothing weight is showed seasonal variations at the seoul, private house than at the mokpo, apartment.. The basal metabolic rate is suggested there in gender difference in the basal metabolic rate (P〈.001). The basal metabolic rate increased gradually with the peak of winter sespectively and deceased again todward summer. The difference of between basal metabolic rate in summer and winter was significant room temperature, of seoul and private house, and light total clothing weight.

  • PDF

A Study on Variation of an Accuracy Rate as the Gradient of a Pistol (총기 경사도에 따른 명중률 변화에 관한 연구)

  • Yeo, Woon-Joo;Lee, Joon-Ho;Choi, Eui-Jung
    • Journal of the Korea Institute of Military Science and Technology
    • /
    • v.14 no.2
    • /
    • pp.167-172
    • /
    • 2011
  • In this paper, a study on variation of an accuracy rate as the gradient of a rifle is shown. In the a state of hostilities, a soldier is not easy to take a shot vertically against the ground. If a soldier shoots as the pistol is inclined, how the accuracy rate is changed. While the pistol is shot, the change of ballistic curve is estimated. And we also verify the accuracy rate through the firing test. Then we compare two results and present some ideas which overcome the decrease of an accuracy rate. Hereafter, it is possible to adapt in the future soldier system and expected that the accuracy rate of the conventional gun is maintained.

A Development of Pulley-type Tensioning Device for a High Speed Railway (고속용 풀리형식 장력조정장치 개발)

  • Cho, Yong-Hyeon;Kwon, Sam-Young;Park, Young;Lee, Ki-Won
    • Proceedings of the KSR Conference
    • /
    • 2006.11b
    • /
    • pp.723-730
    • /
    • 2006
  • In the electrical railway, the tension ascension of contact wire is essential to speed up of train and current collection performance of catenary largely depends on the tension. The tension variation rate of the tensioning device used in existing line limits within 5%, and the tension variation rate of the spring-type tensioning device installed at the section where tensioning length is short bounds within 15%. So it is urgent for us to localize it for high speed line, which the tension variation rate is limited within 3%. Therefore in this study, a pulley-type tensioning device for high speed line is developed. To verify the performance of developed device, a performance test, overload test and failure test is carried out under the code of the Kyung-Bu High Speed line. And it is secured durability performance through a fatigue test.

  • PDF

Characteristics of Ozonizer with Variation of Vaccum in Internal Electrode (고주파전원형 오존발생기의 방전 캡 변화 특성)

  • 이창호;전병준;이상근;송현직;이광식
    • Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
    • /
    • 2003.11a
    • /
    • pp.381-385
    • /
    • 2003
  • In this paper, a co-axial type ozonizer varied with discharge gap was designed and manufactured for investigating $\circled1$ discharge characteristics with variation of output voltage power supply, flow rate and gap $\circled2$ ozone generation characteristics with variation of flow rate, gap and discharge power. pure oxygen was used as process gas of the co-axial type ozonizer. In this paper, a double cylindrical type superposed silent discharge type ozonizer which internal electrode can be produced a vacuum has been designed and manufactured. Discharge and ozone generation characteristics have been investigated in accordance with output voltage of power supply, flow-rate, discharge power and vacuum of internal electrode.

  • PDF

Analysis of Performance and Emissions Characteristics on Gasoline Engine for Hybrid Vehicles with Optimum EGR Rate and the Cylinder Variation of EGR Rate (하이브리드용 가솔린 엔진에서 최적 EGR적용 및 실린더간 편차에 따른 성능 및 배출가스 특성 분석)

  • Park, Cheol-Woong;Choi, Young;Kim, Chang-Gi
    • Transactions of the Korean Society of Automotive Engineers
    • /
    • v.17 no.1
    • /
    • pp.87-95
    • /
    • 2009
  • EGR(Exhaust gas recirculation) provides an important contribution in achieving the development targets of low fuel consumption and low exhaust emission levels on gasoline engine for hybrid vehicles while allowing stoichiometric fuelling to be retained for applications using the three-way catalysts. However, the occurrence of excessive cyclic variation with high EGR normally prevents substantial fuel economy improvements from being achieved in practice. Therefore, the optimum EGR rate in gasoline engine for hybrid vehicles should be carefully determined in order to achieve low fuel consumption and low exhaust emission. In this study, 2 liters gasoline engine with E-EGR system was used to investigate the effects of EGR with optimum EGR rate on fuel economy, combustion stability, engine performance and exhaust emissions. As the engine load becomes higher, the optimum EGR rate tends to increase. The increase in engine load and reduction in engine speed make the fuel consumption better. The fuel consumption was improved by maximum 5.5% at low speed, high load operating condition. As the simulated EGR variation on a cylinder is increased, due to the increase in cyclic variation, the fuel consumption and emissions characteristics were deteriorated simultaneously. To achieve combustion stability without a penalty in fuel consumption and emissions, the cylinder-to-cylinder variations must be maintained under 10%.

Video Quality Variation Minimizing for Real-Time Low Bit Rate Video (영상품질 변화를 최소화하는 실시간 저전송률 영상코딩)

  • Park, Sang-Hyun
    • Journal of the Korea Institute of Information and Communication Engineering
    • /
    • v.11 no.5
    • /
    • pp.868-874
    • /
    • 2007
  • A real-time frame-layer rate control algorithm with a token bucket traffic shaper is proposed for minimizing video duality variation. The proposed rate control method uses a non-iterative optimization method for low computational complexity, and performs bit allocation at the frame level to minimize variation in distortion between frames. In order to reduce the quality fluctuation, we use a sliding window scheme which does not require the pre-analysis process. Therefore, the proposed algorithm does not produce the delay from encoding, and is suitable for real-time low-complexity video encoder. Experimental results indicate that the proposed control method provides better PSNR performance than the existing rate control method.

Quantifying the Variation of Mass Flow Rate generated in a Simplex Swirl Injector by the Pressure Fluctuation for Injector Dynamics Research

  • Khil, Tae-Ock;Kim, Sung-Hyuk;Cho, Seong-Ho;Yoon, Young-Bin
    • Proceedings of the Korean Society of Propulsion Engineers Conference
    • /
    • 2008.03a
    • /
    • pp.218-225
    • /
    • 2008
  • When the heat release and acoustic pressure fluctuations are generated in the combustor by irregular combustion, these fluctuations affect the mass flow rate of the propellants injected through the injectors. Also, the variations of the mass flow rate by these fluctuations again bring about irregular combustion and furthermore that is related with combustion instability. Therefore, it is very important to identify the mass variation for the pressure fluctuation on the injector and to investigate its transfer function. So, we first have studied quantifying the variation of mass flow rate generated in simplex swirl injector by injection pressure fluctuation. To acquire the transient mass flow rate in orifice with time, we have tried to measure of the flow axial velocity and liquid film thickness in orifice. The axial velocity is acquired through theoretical approach after measuring the pressure in orifice and the flow area in the orifice is measured by electric conductance method. As results, mass flow rate calculated by axial velocity and liquid film thickness measuring in orifice accorded with mass flow rate acquired by direct measuring method in the small error range within 1 percents in steady state and within 6 percents as average mass flow rate in pulsated state. Hence this method can be used to measure the mass flow rate not only in steady state but also in unsteady state because the mass flow rate in the orifice can acquire with time and this method shows very high accuracy based on the experimental results.

  • PDF

Influence of the Point Source Inflow on the Water Quality Variation in the Downstream of Hyeongsan River (점오염원 유입이 형산강하류 수질변화에 미치는 영향)

  • Lee, Chang-Soo
    • Journal of Environmental Science International
    • /
    • v.17 no.10
    • /
    • pp.1075-1080
    • /
    • 2008
  • The influence of the point source inflow on the water quality variation in the downstream of Hyeongsan River was investigated. As the results of seasonal variation, the pollutant concentrations of dry season were 1.5-4 times higher than those of wet season. The increase rate of $BOD_5$, $COD_{Mn}$, T-N, T-P due to point source were ranged to $8.1\sim42.6%$, $7.3\sim41.9%$ and $17.1\sim207%$ as the inflow of P1, P2 and P3, respectively. After P1, P2 and P3 inflow, the accumulated increase rate were 64.3%, 32.6%, 93.1% and 258.9% in $BOD_5$, $COD_{Mn}$, T-N, T-P, respectively. It was found that the influence of point source inflow on the water quality in the downstream of Hyeongsan River is severe.

Variation Stack-Up Analysis Using Monte Carlo Simulation for Manufacturing Process Control and Specification

  • Lee, Byoungki
    • Journal of Korean Society for Quality Management
    • /
    • v.22 no.4
    • /
    • pp.79-101
    • /
    • 1994
  • In modern manufacturing, a product consists of many components created by different processes. Variations in the individual component dimensions and in the processes may result in unacceptable final assemblies. Thus, engineers have increased pressure to properly set tolerance specifications for individual components and to control manufacturing processes. When a proper variation stack-up analysis is not performed for all of the components in a functional system, all component parts can be within specifications, but the final assembly may not be functional. Thus, in order to improve the performance of the final assembly, a proper variation stack-up analysis is essential for specifying dimensional tolerances and process control. This research provides a detailed case example of the use of variation stack-up analysis using a Monte Carlo simulation method to improve the defect rate of a complex process, which is the commutator brush track undercut process of an armature assembly of a small motor. Variations in individual component dimensions and process mean shifts cause high defect rate, Since some dimensional characteristics have non-normal distributions and the stack-up function is non-linear, the Monte Carlo simulation method is used.

  • PDF