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A Study on the Design of a New Rotor in Internal Pumps (내부 펌프의 새로운 로버 설계에 관한 연구)

  • Chang, Young-June;Kim, Jae-Hun;Han, Seung-Moo;Kim, Chul
    • Journal of the Korean Society for Precision Engineering
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    • v.24 no.3 s.192
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    • pp.100-107
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    • 2007
  • A internal lobe pump is suitable for oil hydraulics of machine tools, automotive engines, compressors, constructions and other various applications. In particular, the pump is an essential machine element of an automotive engine to feed lubricant oil. The subject of this paper is the theoretical analysis of internal lobe pump whose the main components are the rotors: usually the outer one is characterized by lobes with circular shape, while the inner rotor profile is determined as conjugate to the other. The topic of this paper is the design of a new rotor, which is based on specific performance as different types depending on the shape of the lobe of the outer rotor. First, the design of internal lobe pumps with circular, elliptical, and their combined lobe profiles is considered. The latter is a new type of lobe profile with special shape whose curvature follows a definite function. Then we introduce the performance indexes used for the comparison. Some of these indexes, such as flow rate and flow rate irregularity, are commonly used for the comparison, while specific slipping is particularly suitable in this case. It is possible to notice that the circular and elliptical type is comparable to the circular one or the elliptical one in terms of flow rate irregularity, but has improved performance in terms of specific slipping. Results obtained from the analysis enable the designer and manufacturer of oil pump to be more efficient in this field.

A Study of the Tip Clearance Effect to the Performance of an Axial-Type Fan (축류형 송풍기의 익단간극이 성능에 미치는 영향에 관한 연구)

  • Cho, Chong-Hyun;Jung, Yang-Beom;Kim, Young-Cheol;Cho, Soo-Yong
    • The KSFM Journal of Fluid Machinery
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    • v.11 no.6
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    • pp.7-17
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    • 2008
  • Fan performances are obtained with various tip clearance gaps and stagger angles of the rotor. A tested fan is an axial-type fan of which the casing diameter is 806 mm. Two different rotors are applied to this test. One is designed on the basis of the free vortex method along the radial direction and the other is designed using the forced vortex method. The operating conditions are varied to the ultimate off-design point as well as the deign point. Overall efficiency, total pressure and input power are compared with the tip clearance gaps and different stagger angle. The experimental results show that changing of the stagger angle has minor influence to the performance when the same rotor is applied. When the tip clearance gap is less than 5% of the rotor span, the overall efficiency, total pressure loss and input power reduction are varied linearly with the variation of the tip clearance gaps. On the design point, the overall efficiency is decreased to the rate of 2.8-2.9 to the increasing of the tip clearance, but the changing rate of the overall efficiency is alleviated when the fan operates at off-design points. In particular, this rate is more quickly declined on a fan with the rotor designed using the forced vortex method. The result of the total pressure shows that the pressure reduction rate is a 0.08-0.1 according to the tip clearance, and additionally the input power reduction rate is a 0.045-0.065 at design point.

Dynamic Analysis of the Small-size Gas Turbine Engine Rotor Using Commercial S/W and its Limitations (상용 S/W를 이용한 소형가스터빈엔진 회전체의 동적 구조해석 및 검증)

  • Chung, Hyuk-Jin;Lee, Chong-Won;Hong, Seong-Wook;Yoo, Tae-Gyu
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2009.10a
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    • pp.797-803
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    • 2009
  • The accurate prediction of dynamic characteristics of high speed rotors, such as gas turbines, is important to avoid the possibility of operating the machinery near the critical speeds or unstable speed regions. However, the dynamic analysis methods and softwares for gas turbines have been developed in the process of producing many gas turbines by manufacturers and most of them have seldom been disclosed to the public. Recently, commercial FEM softwares, such as SAMCEF, ANSYS and NASTRAN, started supporting some rotordynamics analysis modules based on 3-D finite elements. In this paper, the dynamic analysis method using commercial S/W, especially ANSYS, is attempted for the small-size gas turbine engine rotor, and the analysis capability and limitations of its rotordyamics module are evaluated for further improvement of the module. As the preliminary procedure, the rotordyamic analysis capability of ANSYS was tested and evaluated with the reference models of the well-known dynamics. The limitations in application of the rotordynamics module were then identified. Under the current capability and limitations of ANSYS, it is shown that Lee diagram, a new frequency-speed diagram enhanced with the concept of H in rotating machinery, can be indirectly obtained from FRFs computed from harmonic response analysis of ANSYS. Finally, it is demonstrated based on the modeling and analysis method developed in the process of the S/W verification that the conventional Campbell diagram, Lee diagram, mode shapes and critical speeds of the small-size gas turbine engine rotor can be computed using the ANSYS rotordynamics module.

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Assessment of Residual Life for In-Service Fossil Power Plant Components Using Grain Boundary Etching Method (입계부식법에 의한 사용중인 화력발전소 요소의 잔여수명평가)

  • Han, Sang-In;Yoon, Kee-Bong;Chung, Se-Hi
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.21 no.1
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    • pp.22-31
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    • 1997
  • The grain boundary etching method as a method for assessing degradation of structural materials has received much attention because it is simple, inexpensive and easy to apply to real components. In this study, the effectiveness of the method is verified by successfully applying the technique to in-service components of aged fossil power plants such as main steam pipes, boiler headers an turbine rotors. A new degradation parameter, intersecting number ratio (N1/N0), is employed. The intersecting number ratio (N1/N0) is defined as the ratio of intersection number (N1) obtained from 5-minute picric acid etched surface to the number (N0) obtained from nital etched surface. Two kinds of test materials, 2.25Cr-1Mo steel and 1Cr-1Mo-0.25V steel, were artificially thermal-aged at 630.deg. C in different levels of degradation., (N1/N0) were measured. And, correlations between the measured values and LMP values calculated from aging temperature and aging time were sought. To check the validity of the correlations obtained in laboratory, similar data were measured from service components in four old Korean fossil power plants. These on-site measurement data were in good correlation with those obtained in the laboratory.oratory.

Dynamic Analysis of the Small-size Gas Turbine Engine Rotor Using Commercial S/W and Its Limitations (상용 S/W를 이용한 소형가스터빈엔진 회전체의 동적 구조해석 및 검증)

  • Chung, Hyuk-Jin;Lee, Chong-Won;Hong, Seong-Wook;Yoo, Tae-Gyu
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.20 no.1
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    • pp.36-44
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    • 2010
  • The accurate prediction of dynamic characteristics of high speed rotors, such as gas turbines, is important to avoid the possibility of operating the machinery near the critical speeds or unstable speed regions. However, the dynamic analysis methods and softwares for gas turbines have been developed in the process of producing many gas turbines by manufacturers and most of them have seldom been disclosed to the public. Recently, commercial FEM softwares, such as SAMCEF, ANSYS and NASTRAN, started supporting some rotordynamics analysis modules based on 3-D finite elements. In this paper, the dynamic analysis method using commercial S/W, especially ANSYS, is attempted for the small-size gas turbine engine rotor, and the analysis capability and limitations of its rotordyamics module are evaluated for further improvement of the module. As the preliminary procedure, the rotordyamic analysis capability of ANSYS was tested and evaluated with the reference models of the well-known dynamics. The limitations in application of the rotordynamics module were then identified. Under the current capability and limitations of ANSYS, it is shown that Lee diagram, a new frequency-speed diagram enhanced with the concept of H in rotating machinery, can be indirectly obtained from FRFs computed from harmonic response analysis of ANSYS. Finally, it is demonstrated based on the modeling and analysis method developed in the process of the S/W verification that the conventional Campbell diagram, Lee diagram, mode shapes and critical speeds of the small-size gas turbine engine rotor can be computed using the ANSYS rotordynamics module.

Effect of the Amount of a Lubricant and an Abrasive in the Friction Material on Friction Characteristics (자동차 제동시 나타나는 마찰특성에 관한 연구(I. 고체 윤활제(Sb2S3)와 연마제(ZrSiO4)의 함량에 따른 영향)

  • Jang, Ho
    • Tribology and Lubricants
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    • v.13 no.1
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    • pp.34-41
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    • 1997
  • Frictional behavior of three automotive friction materials (brake pads) containing different amounts of antimony trisulfide (Sb2S3) and zirconium silicate (ZRSiO4) were investigated using a front brake system. The friction materials were tested on a brake dynamometer (dyno) with gray cast iron rotors. The dynamometer(dyno) test simulated the dragging of a ehicle maintaining 70 km/h and vehicle stops from 100 km/h using 20 different combinations of initial brake temperature (IBT) and input pressure (IP). The results showed a strong influence of the relative amount of Sb2S3 and ZrSiO4 in friction materials on friction characteristics. Friction stability was improved with the higher concentration of Sb2S3 in the friction material. Torque variation during drag cycle was increased with an increase of the ZrSiO4 concentration in the friction material. Average friction coefficient and the wear rate of the friction material increased by using more aggressive friction materials containing more ZrSiO4 and less Sb2S3. Generation of the disk thickness variation (DTV) increased when friction materials with higher concentration of ZrSiO4 were used Careful examination of DTV change showed that aggressiveness of the friction material played an important role in determining torque variation.

A Study of the Royal Lady's Dress in Late Joseon Dynasty According to the King's Wedding Process (가례시 절차에 따르는 조선후기의 왕실여성 복식연구)

  • Kim, Soh-Hyeon
    • Journal of the Korean Society of Costume
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    • v.59 no.3
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    • pp.96-108
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    • 2009
  • This study is made on the royal lady's dress In late Joseon dynasty according to the King Heon-jong and Lady Kyung-bin's Wedding Diary in the year of Jung-mi(1847) and summarised as follows: Girls' full dress was a set of a red skirt, a violet undo. jacket, and a light yellow jacket and a green Gyeon-ma-gi(a kind of top jacket) with he. hair Saeng-meo-ri hanging Do-tu-rak-daeng-gi(a kind of hair ribbon). At the big ceremony, girls wore a green Dang-ui instead of Gyeon-ma-gi. A girl picked up as a royal concubine wore a green Won-sam, which was decorated with gilt letters meaning longevity, patched emblems of gilt letter meaning longevity on the breast and on the back, belted with Bong-dae(a red sash with gilt phoenexes), like a princess's full dress. At the Kyung-bin's installation of Crown Princess and her first greeting ceremony with royal elders, she wore a green Won-sam as a formal dress, which had an embroidered emblem of phoenix, the belt with crystal ornaments, Pae-ok(佩玉), Kyu(圭) of blue jade, Shou(綬) with an phoenix. At a Dong-wrae-yun(drinking ceremony after bride and bridegroom's bowing to each other), she wore the embroidered red Jang-sam as a formal dress. Kyung-bin wore a purple Won-sam with Bong-dae as a full dress for a royal feast. According to the occasions, the same dress was differentiated with ornaments and rotors. Ji-keum-bal was an attire for ordinary ceremony. The attire was equipped with a woven gold green Dang-ui with an emblem of phoenix, a blue gilt underskirt and a red gilt overskirt. No-ui was worn as outdoor clothes. Jang-sam was worn by various classes, so it was differentiated with materials and names according to her class.

Application of Superconducting Flywheel Energy Storage System to Inertia-Free Stand-Alone Microgrid

  • Bae, SunHo;Choi, DongHee;Park, Jung-Wook;Lee, Soo Hyoung
    • Journal of Electrical Engineering and Technology
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    • v.12 no.4
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    • pp.1442-1448
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    • 2017
  • Recently, electric power systems have been operating with tight margins and have reached their operational limits. Many researchers consider a microgrid as one of the best solutions to relieve that problem. The microgrid is generally powered by renewable energies that are connected through power converters. In contrast to the rotational machines in the conventional power plants, the converters do not have physical rotors, and therefore they do not have rotational inertia. Consequently, a stand-alone microgrid has no inertia when it is powered by the only converter-based-generators (CBGs). As a result, the relationship between power and frequency is not valid, and the grid frequency cannot represent the power balance between the generator and load. In this paper, a superconducting flywheel energy storage system (SFESS) is applied to an inertia-free stand-alone (IFSA) microgrid. The SFESS accelerates or decelerates its rotational speed by storing or releasing power, respectively, based on its rotational inertia. Then, power in the IFSA microgrid can be balanced by measuring the rotor speed in the SFESS. This method does not have an error accumulation problem, which must be considered for the state of charge (SOC) estimation in the battery energy storage system (BESS). The performance of the proposed method is verified by an electromagnetic transient (EMT) simulation.

An Experimental Study of the Performance Characteristics on a Multi-Stage Micro Turbine with Various Stages (다단 마이크로터빈에서 단수 변화에 따른 터빈의 성능에 관한 실험적연구)

  • Cho, Chong-Hyun;Cho, Soo-Yong;Choi, Sang-Kyu
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.33 no.12
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    • pp.76-82
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    • 2005
  • An experimental study on an axial-type micro turbine which consists of maximum 6 stages is conducted to measure aerodynamic characteristics on each stage. This turbine has a 2.0 flow coefficient, 3.25 loading coefficient and 25.8mm mean diameter. The solidity of stators and rotors is within a 0.67~0.75, and the off-design performance is measured by changing the load after adjusting the mass flowrate and the total pressure to constant at inlet. A maximum specific output power of 2kW/kg/sec is obtained in one stage, but the increment of the specific output power with increasing stages is alleviated. In case of torque, the increment of the torque maintains to constant at low RPM region, but its increment become dull at high RPM region. The efficiency of the micro turbine becomes low because the tip gap effect is great due to the small blade, but it could be improved by increasing the stages.

The Development of Absorption Elements of Ceramic Rotors for the Semiconductor Clean Room System (반도체 클린룸용 세라믹 Rotor 흡착제 개발)

  • 서동남;하종필;정미정;문인호;조상준;김익진
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.1 no.2
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    • pp.33-40
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    • 2000
  • The present invention relates to a absorption rotor for removed VOC(volatile organic compound) and humidity in semiconductor clean room system. A absorption rotor medium is made by NaX zeolite and TS-1 zeolite formed on a honeycomb matrix of ceramic papers. The crystallization of NaX zeolite was hydrothermal reaction, and NaX zeolite crystals of a uniform particle size of 5μm were synthesized that NaX zeolite seed crystals (2~3μm) added in a batch composition at levels of 3~15 wt%. The seeding resulted in an increase in the fraction of large crystals compared with unseeded batches and successfully led to a uniform NaX zeolite crystal. The microporous zeolite-type titanosilicate(TS-1) was synthesized by different of the reactant solution pH. The pH range of reactant solution has been changed from 10.0 to 11.5 TS-1 zeolite (ETS-10), having a large pore(8~10 \AA), was synthesized at 10.4 of pH, since TS-1 zeolite (ETS-4), having a small pore(3~5\AA), was synthesized at 11.5 of pH.

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