• Title/Summary/Keyword: High RPM

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Particle Morphology via Change of Ground Particle for Various Experimental Conditions During a Grinding Process by Three Kinds of Media Mills (세 가지 매체형 분쇄기를 이용한 분쇄공정에서 다양한 실험 조건에 대한 입자형상변화)

  • Sakuragi, Shiori;Bor, Amgalan;Lee, Jehyun;Choi, Heekyu
    • Particle and aerosol research
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    • v.11 no.1
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    • pp.9-19
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    • 2015
  • This study investigated the effects of ball mill operation condition on the morphology of raw powders in the dry-type milling process using three types of ball mills traditional ball mill, stirred ball mill and planetary ball mill. Furthermore, since spherical powders offer the best combination of high hardness and high density, the optimum milling condition to produce sphere-shaped powders was studied. The applied rotation speed ranged from 200rpm (low rotation speed) to 700rpm (high rotation speed). The used ball size ranged from 1mm to 5mm. The metal powder morphology was studied using SEM, XRD and PSA. The aimed spherical powders could be obtained under the optimum experimental conditions: traditional ball mill(200rpm, 1mm ball), planetary ball mill (500rpm, 1mm ball) and also planetary ball mill (700rpm, 1 and 3 mm ball). The results show to the development of new material using spherical type copper powder/CNT composites for air-craft and automotive applications.

Conductivity·Filling Rate Analysis for Die-Casting Centrifugal Casting Machine (다이캐스팅형 원심주조기에 대한 충진율·전도율 해석)

  • Lee, Yang-Chang;Lee, Joon-Seong
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.16 no.4
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    • pp.2364-2369
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    • 2015
  • In this paper, the optimum RPM was suggested comparing rotor filling rate of RPM through the analysis of rotor's filling rate as studying and developing centrifugal-casting machine's method for high precision rotor in order to increase the related types of business's productivity. The result was similar to other result in industrial site, showing 99.47% of filling rate when rotational speeds are 600 rpm, so it is considered that if this result is conducted with additional research, it will be possible to plan a better process design. Besides, the optimum temperature of compact ladle was examined to produce high quality casting product through the analysis of compact ladle's conductivity. In the case of the heating device's absence using nicrome wire, Al solution solidifies falling drastically into $427^{\circ}C$. However, it is feasible to work over $427^{\circ}C$ which is the melting temperature of aluminium solution when the heating device of nicrome wire is included. It reveals that there is little temperature change.

A Study on the Development of Hydrostatic High Speed Spindle for Grinding Machine (고속 연삭기용 유정압 스핀들 개발에 관한 연구)

  • Kim, Jeong-Suk;Cho, Yong-Kwon;Park, Jin-Hyo;Moon, Hong-Man
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.20 no.1
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    • pp.96-100
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    • 2011
  • The hydrostatic bearings have a relatively small run-out comparing to its shape error by fluid film effect in hydrostatic state as like pneumatic bearing and have a high stiffness, load capacity and damping characteristics. As there is no maintenance and semipermanent in these bearing type, it has been usually adopted as main spindle bearing for grinding machine. In this thesis, to develop hydrostatic bearing for high speed spindle, the cooler setting temperature, bearing clearance and nozzle pressure of belt-driven hydrostatic bearing are investigated. The bearing temperature is decreased, as the cooler setting temperature is lower, nozzle pressure is higher and bearing clearance is wider. The front temperature of bearing is nearly $8^{\circ}C$ higher than the rear one up to 13,000 rpm of spindle revolution. The thermal deflection of X-axis is ${\pm}16\;{\mu}m$ in range of 12,000 rpm-13,000 rpm. Therefore, it is conformed that the built-in motor hydrostatic bearing can be used to high speed spindle.

The Diagnosis of Cooling Tower System (Cooling Tower System 진동 진단)

  • Lee, Sun-Hwi
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2007.11a
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    • pp.1090-1094
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    • 2007
  • The aim of this study is to estimate the cause of Cooling Tower vibration and eliminate the faults of fan with high vibration in spite of overhaul. The cause of high vibration was that the natural frequency of fan blade coincide with second blade pass frequency. To achieve reduction of Cooling Tower vibration, change motor speed from 1784rpm to 1714rpm, and then the vibration has reduced conspicuously.

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Changes in Moisture Permeability and Waterproofness of High-density Fabric by Repeated Laundering and Condition (고밀도 직물의 반복세탁 및 세탁조건에 따른 투습.발수성 변화)

  • Roh, Eui-Kyung;Han, Jung-Eun;Kim, Eun-Ae
    • Journal of the Korean Society of Clothing and Textiles
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    • v.34 no.11
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    • pp.1798-1811
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    • 2010
  • This research evaluates the changes in the comfort-related properties of high-density fabric, such as moisture permeability and waterproofness, in order to assess the relative importance of laundry conditions for clothing properties after repeated laundering and suggest the best laundering conditions for high-density fabric through the identification of the most influential factor. A commercial high-density fabric was washed 25 times in a drum-type washer using nine different laundry conditions based on profiles derived from a fractional factorial design. To evaluate the changes in the comfort-related properties of the fabric, pore size, air permeability, water vapor transport, water repellency, and water resistance were measured. The comfort-related properties of the fabric deteriorated after repeated laundering by the damaged surface finish; in addition, the damaged surface also changed the pore size. As a result, the water repellency and water resistance decreased. The detergent was the most responsible factor to change the properties among the four factors of detergent, hardness, temperature, and RPM. The best laundering conditions for the fabric was a neutral detergent, soft water of 70ppm, a temperature of $15^{\circ}C$, and 30rpm.

The Analysis of High Frequency Signal for 7tonf-class Power Pack System of KSLV-II (한국형발사체 7톤 파워팩 시스템 고주파 신호 분석)

  • So, Younseok;Yi, Seungjae;Lee, Kwangjin;Kim, Seunghan;Han, Yeoungmin
    • Journal of the Korean Society of Propulsion Engineers
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    • v.20 no.3
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    • pp.96-102
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    • 2016
  • The 7tonf-class power pack test at turbopump test facility in Naro space center was performed for confirmations of starting/running/ending operation characteristics before 7tonf rocket engine hot-firing test. The dynamic pressure mounted on a combustion chamber of gas generator is measured under 0.2 bar which does not conditioned to the unstable combustion. The analysis results of RPM and acceleration sensors mounted on the turbopump, the power pack test was performed to the estimated RPM with the stable combustion.

Performance Evaluation on the Addition of Low-pressure Loop EGR in a Commercial Diesel Engine (상용 디젤엔진의 저압 순환 EGR 추가에 대한 성능 평가)

  • Wang, Tae-Joong;Lee, Jong-Yoon;Shim, Eui-Joon;Kim, Duk-Sang;Lee, Dong-In
    • Transactions of the Korean Society of Automotive Engineers
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    • v.19 no.2
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    • pp.105-110
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    • 2011
  • Through this study, the performance evaluation on the addition of low-pressure loop EGR(Exhaust Gas Recirculation) in a 6.0 L commercial diesel engine was carried out using WAVE modeling and simulation. Since the key technology of advanced diesel engine combustion such as low-temperature combustion is to steadily supply high rates of EGR in a wide operating range, the current study could be effectively contribute to the design and development processes of up-to-date diesel engine systems as real-world reference data. The current simulation results show that the system in which low-pressure loop EGR is added shows almost 2.3 times increase in maximum EGR rate at 1000 rpm as well as almost 1.6 times increase at 2200 and 1600 rpm in comparison with an engine system employing high-pressure loop EGR only. Also, both turbocharger axis speed and charging pressure level did not deteriorate due to the addition of low-pressure loop EGR at 2200 and 1000 rpm, but they were fairly decreased at 1600 rpm.