• Title/Summary/Keyword: Speed Loss

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Analysis of Performance Characteristics of Swash-Plate-Type Hydraulic Piston Motor (사판식 유압 피스톤모터의 성능특성 분석)

  • Lee, Yong-Bum;Kim, Kwang-Min
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.36 no.11
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    • pp.1441-1446
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    • 2012
  • An axial-piston-type hydraulic motor involves friction and leakage losses at the sliding parts, contact loss at the mechanism assembly parts, volumetric loss caused by the pressure drop, housing oil churning loss and compressibility from the hydraulic oil pipe resistance, etc. the friction and volumetric loss at the hydrostatic bearing between the piston shoe and the swash plate rotating at high speed and having an oil film gap of 8-15 ${\mu}m$ strongly affects the total efficiency of the hydraulic motor. In this study, a variable swash-plate-type hydraulic piston motor operating under a maximum pressure of 35 MPa, maximum speed of 2,500 rpm, and displacement of 320 cc/rev is tested to verify the optimal ratio of the hydrostatic bearing which is closely related to the hydraulic motor performance.

Harvesting performance of an experimental pick-up type pulse crop harvester for green kernel black bean

  • Choi, Yeong Soo;Han, Byung Hee;Yoo, Soo Nam
    • Korean Journal of Agricultural Science
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    • v.44 no.1
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    • pp.114-122
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    • 2017
  • An experimental pick-up type pulse crop harvester was built and its harvesting performance for green kernel black bean was evaluated. Field bean loss and harvested bean quality of the harvester were analyzed according to engine speeds of 2,000; 2,400; 2,800; 3,000; and 3,200 rpm, and travel speeds of 0.6; 1.0; and 1.4 m/s. Operating conditions and field capacity of the harvester for proper harvesting were estimated. The harvester had an optimum performance at a grain moisture content of 13.4%, an engine speed of 3,000 rpm, and a travel speed of 1.2 - 1.3 m/s. Subsequently, the picking-up, discharging, and total bean loss ratios were found to be 1.6, 1.3, and 2.9%, respectively. The whole bean, damaged bean, unthreshed bean, and foreign material ratios were determined to be 96.2, 1.0, 0.1, and 0.3%, respectively. Results showed that the harvester had lower bean loss and higher harvested bean quality than those of imported bean combines. The harvester could harvest 2 rows with a crop spacing of an approximately 1.4 m. Its optimum travel speed was estimated to be approximately 1.2 m/s when harvesting performance was taken into account using such variables as field bean loss and harvested bean quality for green kernel black bean. Effective field capacity of the harvester was estimated at approximately 40 a/h.

The Application of CFD for the Duct System Design of CRW aircraft (CRW 비행체 덕트 시스템 설계를 위한 CFD의 활용)

  • Jung Y. W.;Jun Y. M.;Yang S. S.
    • 한국전산유체공학회:학술대회논문집
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    • 2003.08a
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    • pp.200-205
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    • 2003
  • The Canard rotor/wing (CRW) aircraft concepts offer great potential for application by allowing the use of a common propulsion system for high-speed cruise and low-speed powered lift. Using the rotor for lift in both flight modes increases its utility. In the hovering mode, the exhausted gas from an gas turbine engine is accelerated through the duct system and it provides the tipjet power for rotor system enough to lift the aircraft. In the cruise mode, the rotor is fixed and the exhausted gas is extracted through the main nozzle, such that the aircraft is able to flight with high speed. The duct system was designed using 1-D fanno line flow theory and empirical data. However, the empirical data of the pressure loss coefficient for various bending and dividing ducts were not enough to design our duct system adaptively. Therefore, using 3-D CFD analysis we obtained the pressure loss coefficient for our duct models and chose the appropriate bending or diving duct type. In this paper, we used the CFD-ACE+ software package for the CFD analysis and the modeling of duct system. Through the 3-D CFD analysis, we investigated also the pressure loss and the velocity distributions of the designed whole duct system as well as the blade duct. Comparing the 3-D CFD result with 1-D analysis result, we lessened the uncertainty of the designed duct system and speculated the problem that was not concerned in design state.

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A Handover Mechanism for QoS Guarantee in WiBro (초고속 휴대 인터넷 망에서 서비스 품질 보장을 위한 핸드오버 메커니즘)

  • Yeom Hong-Ju;Kim Hwa-Sung
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.31 no.7A
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    • pp.659-665
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    • 2006
  • When using the Mobile IP which is the representative technology to secure the mobility in general IP networks, the packet loss during the handover is inescapable. To remedy the packet loss problem, the smooth handover was introduced. However, the smooth handover causes the packets sequence disruption during the packet forwarding procedure and it may result in the degradation of the network performance. The same problem also occurs in the WiBro (High-speed Portable Internet) system that is the next generation portable IP service system. The WiBro system, which provides the high speed data service just like xDSL and leased line in wired internet, aims to guarantee the portability, mobility, and the differentiated service based on IEEE 802.16. So, the handover mechanisms that solve the problems of packet loss and packet sequence distribution are required in the WiBro system. In this paper, we propose the handover mechanism and the packet sequence control algorithm that provide the reliability and the differentiated service for the unicast service in the WiBro system.

The Effects of the Drum Configuration and the Crop Moisture Content on the Threshing of Malting Barley (급동형태(扱胴形態)와 작물(作物)의 수분함량(水分含量)이 맥주보리의 탈곡성능(脱糓性能)에 미치는 영향(影響))

  • Lee, Seung Kyu;Kim, Sung Tae;Min, Young Bong
    • Journal of Biosystems Engineering
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    • v.7 no.2
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    • pp.45-56
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    • 1983
  • The purpose of this experiment was to evaluate the effect of the drum structures and crop moisture contents on the performance of newly developed throw-in type axial thersher. Sachun No.2 malting barley with four different crop moisture levels was used as the testing material. Four different types of threshing drum; the cylindrical drum-equipped with teeth or rubber bars and the conical drum-equipped with teeth or rubber bars were tested. The results are summarized as follows; 1. The threshing efficiency of cylindrical drum was higher than that of the conical one, and the drum with teeth was more effective in threshing than the one with bars. However, the higher the threshing efficiency over the whole range of moisture levels and drum speeds given, the more the rapid and unexpectable variations in threshing efficiencies 2. The separation efficiency of the conical drum was decreased as drum speed was increased and was not so much influenced as crop moisture content. But in case of the cylindrical drum, the result was shown in opposite way to that of the conical one. The separation efficiency of the drum with teeth was higher than that of the drum with bars and no significant decrease in separating efficiency was found at wet crop condition. 3. Foreign matters other than grain passing through the concave sieve was decreased as crop moisture content was increased, and the purity was increased at middle range of drum speed regardless of drum types. 4. Minimum grain loss was found at 700 rpm to 800 rpm of drum speed for all types of drums. The effect of crop moisture content on total grain loss was varied with drum types. As far as the grain loss is concerned, the conical drum having teeth was not so greatly influenced by various crop moisture contents and drum speeds as compared with the other types of drum. 5. Generally, the crop moisture content has more relevant effect on the germination than the drum speed regardless of drum types. The germination percentage of grain threshed by the conical drum and the bar attached drum were higher than those of cylindrical one and teeth attached one, respectively.

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Development of the software for high speed data transfer of the high-speed, large capacity data archive system for the storage of the correlation data from Korea-Japan Joint VLBI Correlator (KJJVC)

  • Park, Sun-Youp;Kang, Yong-Woo;Roh, Duk-Gyoo;Oh, Se-Jin;Yeom, Jae-Hwan;Sohn, Bong-Won;Yukitoshi, Kanya;Byun, Do-Young
    • Bulletin of the Korean Space Science Society
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    • 2008.10a
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    • pp.37.2-37.2
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    • 2008
  • Korea-Japan Joint VLBI Correlator (KJJVC), to be used for Korean VLBI Network (KVN) in Korea Astronomy & Space Science Institute (KASI), is a high-speed calculator that outputs the correlation results in the maximum speed of 1.4GB/sec.To receive and record this data keeping up with this speed and with no loss, the design of the software running on the data archive system for receving and recording the output data from the correlator is very important. But, the simple kind of programming using just single thread that receives data from network and records it by turns, can cause a bottleneck effect while processing high speed data and a probable data loss, and cannot utilize the merit of hardwares supporting multi core or hyper threading, or operating systems supporting these hardwares. In this talk we summarize the design of the data transfer software for KJJVC and high speed, large capacity data archive system using general socket programming and multi threading techniques, and the pre-BMT(Bench Marking Test) results from the tests of the storage product providers' proposals using this software.

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Design Essential Element Technology of Catenary System be in Correspondence with Speed-up (고속화에 대응한 전차선로 설계 요소기술)

  • Chang, Sang-Hoon;Kim, Yang-Soo;Park, Byung-Soo
    • Proceedings of the KIEE Conference
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    • 2005.05b
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    • pp.75-78
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    • 2005
  • The decisive criteria to determine collection performance is the contact force between pantograph and catenary. The contact force consists of a static force and dynamic force related to vibration characteristics, train speed and etc. The low contact force leads to the loss of contact, and most countries regulate it below 1% at operation speed. This study presents a technical overview of criteria for collection performance of catenary system.

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Study on the tilting pad mechanism of swash plate type axial piston motor (사판식 액셜 피스톤 모터의 틸팅 패드의 매카니즘에 대한 연구)

  • 김진욱;이춘태;이진걸;이만형
    • 제어로봇시스템학회:학술대회논문집
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    • 1990.10a
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    • pp.681-686
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    • 1990
  • The existing Swash Plate Type Axial Piston Motor rapidly drops efficiency at high speed in comparison with low speed. This is the reason why the motor was designed only in a viewpoint of minimum of power supply. But, in this paper, the motor which was optimally designed in a veiwpoint not only power supply but also load capacitancy, flow loss volume, axial stiffness and tilting stiffness keeps up high efficiency at high speed.

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A Study on the Power Loss Simulation of Inverter and Converter for Elevator (승강기용 전력변환장치의 IGBT 전력손실에 관한 연구)

  • Cho, Su-Eog
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.28 no.12
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    • pp.116-123
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    • 2014
  • In case of power electronics, th power loss and EMI noise of IGBT is different depends on a adopting technology with the same power rating. To reduce the EMI noise, we could increase the resistance of gate. But in this case, the power loss of IGBT is increased, In this paper, we simulated the power loss of IGBT with the speed profile of elevator by the changing IGBT type, the voltage between gate and emitter, the resistance of gate in converter and inverter for elevator. To optimize the power electronics with the satisfied life time, It is necessary that we calculate the power loss and the rise of temperature in IGBT with the adopting technology type, the resistence of gate, the voltage between gate and emitter.

Contact Loss Simulator to Analyze the Contact Loss of a Rigid Catenary System

  • Jung, No-Geon;Kim, Jae-Moon
    • Journal of Electrical Engineering and Technology
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    • v.12 no.3
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    • pp.1320-1327
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    • 2017
  • In this paper, a contact loss simulator for a rigid catenary system was designed and used to analyze the effect on the power source according to the conditions of the rigid catenary system and pantograph. R-bar applied to a high-speed train among the real rigid catenary system was used in the contact loss simulator for rigid catenary systems. The excitation frequency generated with the movement of the railway vehicle was simulated. The characteristics according to the frequency and amplitude of the excitation frequency and the presence or absence of pantograph movement were analyzed. This work is considered to be helpful in analyzing the characteristics of contact loss in the interface between a real rigid catenary system and a rail vehicle.