• Title/Summary/Keyword: Varied Section

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Fogrming Experiment using Improved CNC Extruder and FE Analysis in Varied Section Extrusion Process (가변단면 압출기 제조와 그에 따른 성형실험 및 유한요소 해석)

  • Choi, H.J.;Lim, S.J.;Shin, H.T.;Choi, S.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2007.10a
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    • pp.128-131
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    • 2007
  • It is very important that there are saving resource and energy in the future as well as in these day. Weight saving of structural parts, which are formed by extrusion, plays a key role in manufacturing field. Especially these aluminum parts used in the car need other processes to vary the cross section in the axial direction. Thus, applications of these parts are limited by high cost. if the cross section of the parts is variable by only extrusion, application of extruded aluminum parts will more increase. Therefore, a new CNC extruder which can control the section area of a car part was invented the nation's first. Using the extrusion machine, the experiment and FE analysis were performed during the varied section extrusion process.

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A Study on the Rotary Tidal Current in the East China Sea (동지나해 어장의 회전 조류에 관하여)

  • 김진건
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.22 no.2
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    • pp.1-6
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    • 1986
  • Even though it is well known that the tidal current in the East China Sea rotates clockwise, few report can be found about the precise pattern of it. To furnish some information available for the stow net fishermen, the author carried out the observation over 235 semidiurnal tidal cycle to investigate the pattern of the set and the rate of tidal current in the Korean fishing section 250 and 494, by reading the current meter and by tracing the corner reflectors with radar onboard the anchored obsen'ation vessel, from May 12, 1984 through February 27, 1986. The results obtained are as follows: 1. The mean semidiurnal tidal cycle was 12 h 20 m during spring tide, and 12 h 30 m during neap tide. 2. The mean interval from the calculated time of high water until the current began to set north was 2 h 30 m and 2 h 15 m in the fishing section 250 and 494 respectively, and the mean interval from the time of low water current began to set south was about 2 h 0 m in both sections. 3. In comparison of the occupied times to vary the set from one of 8 principal bearing points to the neighboring one, the shortest was while the set varied from N to NE and S to SW in the section 250 and 494 respectively. Contrary the longest was while the set varied from SE to S and from W to NW in the section 250 and 494 respectively. 4. In comparison of the rate while the set varied from one of 8 principal bearing points to the neighboring one, the fastest was while the set varied from SE to Sand NW to N in the section 250, and E to SE and W to NW in the section 494. Contrary the slowest was while the current set to NE and S W in the section 250, and N, NE and S W in the section 494.

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CNC Extruder for Varied Section Products (CNC 제어 가변단면 압출기 개발)

  • Choi, H.J.;Lim, S.J.;Shin, H.T.;Choi, S.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2007.05a
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    • pp.246-249
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    • 2007
  • It is very important that there are saving resource and energy in the future as well as in these day. Weight saving of structural parts, which are formed by extrusion, plays a key role in manufacturing field. Extruded aluminum parts' cross sections are constant in the axial direction by conventional extrusion method. Especially these aluminum parts used in the car need other processes to vary the cross section in the axial direction. Thus, applications of these parts are limited by high cost. if the cross section of the parts is variable by only extrusion, application of extruded aluminum parts will more increase. Therefore, a new CNC extruder which can control the section area of a car part was invented the nation's first. Using the extrusion machine, the experiment was performed to validate the workability.

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An analysis of ground supported farm silo with variable thickness (I) -Part I mechanical characteristics of shell with Variable thickness- (지반과 구조물사이의 상호작용을 고려한 변단면 도통형쉘의 해석 (I) -변단면 쉘의 역학적 특성 (I)-)

  • 조진구;조현영
    • Magazine of the Korean Society of Agricultural Engineers
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    • v.31 no.4
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    • pp.58-71
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    • 1989
  • This study aims to develop a computerized program for analysis of the ground-supported cylindrical shell structure with step varied section and to find out its mechanical characteri- stics through application of the developed program to the analysis of a ensiled farm silo as a model structure. The thickness of wall and bottom-plate of farm silo is assumed to be step-varied and its detailed structural dimensions are presented in Tab. 1 and 2. Several numerical case studies show that sectional stresses of the sample structures are largely reduced by adopting "varied section" design technique. And, other major results ob- tained from this study are summarize4 as follows ; 1. The variation of wall-thickness has a great influence on bending stresses of wall. Ho- wever, the larger the relative thickness of bottom-plate is, the smaller the influence is. 2. The magnitude of thickness of projecting toe of bottom-plate has negligible effect on sectional stresses 3. The conventional design methodology, which assumes the bottom edge of wall as clam- ped on ground, is proved to be discarded through the numerical analysis. 4. It is found that the "varied section" design technique should get similar effects as in the case of thick bott6m-plate having uniform thickness. 5. The variation of wall-thickness has a considerable effect on the bending stresses of bo- ttom-plate. Especially, this phenomenon is very remarkable in its projecting toe. In some cases. the negative bending moment may be acted on.

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Varied Flow Analysis for Linear Drainage Channels (선형 배수로에 대한 부등류 해석)

  • Ku, Hye-Jin;Jun, Kyung-Soo
    • Journal of Korea Water Resources Association
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    • v.41 no.8
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    • pp.773-784
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    • 2008
  • The present study was carried out to examine flow properties in linear drainage channels such as road surface drainage facilities. The finite difference formulation for the varied flow analysis was solved for flow profiles in the channels. Starting the first step at the control section, the Newton-Raphson method was applied for producing numerical solutions of the equation. We considered two types of linear drainage channels, a channel with one outlet at downstream end and a channel with two outlets at both ends. Moreover, the flow analysis for various channel slopes was performed. However, we considered channels with the two outlets of slopes satisfying the condition that the both ends are the control section. The maximum of those slopes was decided from the relation between the channel slope and the location of control section. The flow of a channel with one outlet was calculated upward and downward from the control section existing in channel or upward from the control section at downstream end. The flow of a channel with two outlets at both ends were calculated for upstream and downstream channel segments divided by the water dividend, respectively and the flow analysis was completed when the water depth at the water dividend calculated from upstream end was equal to that calculated from downstream end. If the slope was larger than the critical slope, the channel with two outlets was likely to behave like the channel with one outlet. The maximum water depth was investigated and compared with that calculated additionally from the uniform flow analysis. The uniform flow analysis was likely to lead a excessive design of a drainage channel with mild slope.

Shear lag effect of varied sectional cantilever box girder with multiple cells

  • Guo, Zengwei;Liu, Xinliang;Li, Longjing
    • Structural Engineering and Mechanics
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    • v.84 no.3
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    • pp.295-310
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    • 2022
  • This paper proposes a modified bar simulation method for analyzing the shear lag effect of variable sectional box girder with multiple cells. This theoretical method formulates the equivalent area of stiffening bars and the allocation proportion of shear flows in webs, and re-derives the governing differential equations of bar simulation method. The feasibility of the proposed method is verified by the model test and finite element (FE) analysis of a simply supported multi-cell box girder with constant depth. Subsequently, parametric analysis is conducted to explore the mechanism of shear lag effect of varied sectional cantilever box girder with multiple cells. Results show that the shear lag behavior of variable box-section cantilever box girder is weaker than that of box girder with constant section. It is recommended to make the gradient of shear flow in the web with respect to span length vary as smoothly as possible for eliminating the shear lag effect of box girder. An effective countermeasure for diminishing shear lag effect is to increase the number of box chambers or change the variation manner of bridge depth. The shear lag effect of varied sectional cantilever box girder will get more server when the length of central flanges is shorter than 0.26 or longer than 0.36 times of total width of top flange, as well as the cantilever length exceeds 0.29 times of total length of box's flange. Therefore, the distance between central webs can adjust the shear lag effect of box girder. Especially, the width ratio of cantilever plate with respect to total length of top flange is proposed to be no more 1/3.

Comparison of electrophoretic karyotypes in fusarium

  • Min, Byung-Re
    • Journal of Microbiology
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    • v.33 no.4
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    • pp.334-338
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    • 1995
  • The electrophoretic karyotypes of 6 species in different Fusarium sections were examined by using contour-clamped homogeneous electric field (CHEF) gel electrophoresis. Intact chromosomal DNA was prepared from protoplasts and up to 9 distinct bands were separated on 0.7% or 0.8% agarose gel under several different conditions. Putative chromosome numbers varied from 6 to 9 amd polymorphic karyotypes were observed in different Fusarium sections. Using Schizosaccharomyces pombe and Saccharomyces cerevisiae chromosomes as standards, the sizes of the Fusarium spp. chromosomes were estimated. The electrophoretic karyotypes of F. moniliforme and F. subglutinans (section Liseola) were similar. Unidentified filamentour fungi, F. beomiforme was much closer to F. axysporum (section Elecgans) in karyotype and the karyotypes of F. napiforme were more similar to those of section Liseola than any other sections. F. graminearum (section Discolor) had a distinctive electrophoretic karyotype.

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An Experimental Study of Instability Mode Analysis in a Model Gas Turbine Combustor (모형 가스터빈 연소기에서의 연소 불안정 모드 분석에 관한 실험적 연구)

  • Lee, Jang-Su;Kim, Min-Ki;Park, Sung-Soon;Lee, Jong-Guen;Yoon, Young-Bin
    • Journal of the Korean Society of Combustion
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    • v.15 no.1
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    • pp.12-21
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    • 2010
  • The main objective of this study was investigation of combustion instability characteristics in a lean partially premixed gas turbine dump combustor. Dynamic pressure transducers were located on combustor and inlet section to observe combustion pressure oscillation and difference at each measurement places. Also flame shape and $CH^*$ chemiluminescence were measured using a high speed ICCD camera. The combustor length was varied in order to have different acoustic characteristics from 800 to 1090 mm. The first section of this paper shows the stability map in model gas turbine combustor. And the effects of combustor length, mixture velocity in the mixing section and equivalence ratio were studied by the pressure perturbation and heat release oscillation. Also, the instability frequency and mode analysis were studied in last two sections. We observed two dominant instability frequencies in this study. Lower frequencies were obtained at lower equivalence ratio region and it was associated with a fundamental longitudinal mode of combustor length. Higher frequencies were observed in higher equivalence ratio conditions. It was related to secondary longitudinal mode of combustor and mixing section. In this instability characteristics, pressure oscillation of mixing section part was larger than pressure oscillation of combustor. As a result, combustion instability was strongly affected by acoustic characteristics of combustor and mixing section geometry.

Measurement of Single Phase and Condensation Heat Transfer Coefficients of Ammonia in a Horizontal Tube (암모니아의 수평관내 단상 및 응축 열전달계수의 측정)

  • 백영진;장영수;김영일
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.12 no.6
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    • pp.561-569
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    • 2000
  • Single phase and condensation heat transfer characteristics of ammonia in a horizontal tube have been investigated experimentally The horizontal test section is composed of smooth SUS316 tube for refrigerant flow, surrounding annulus for water flow, and temperature and Pressure measuring sensors. For single phase test, subcooled ammonia mass flux was varied from 320 to 501 kg/mrs and temperature was varied from 18 to $47^{\circ}C$. For condensation test, mass flux and saturation temperature were varied from 86 to 128 kg/$m^2$s and 34 to $47^{\circ}C$, respectively. The equations of Gnielinski Soliman et al., Traviss et at., Cavallini and Zecchin, Shah, Chen et al., Tandon et al., and Chilli and Anand were compared with the experimental data. New correlations are proposed based on the experimental results and the absolute mean deviation of the experimental data becomes 1.0% for single phase test and 4.9% for condensation test.

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