• Title/Summary/Keyword: Bead Shape

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The Crush Energy Absorption Capacity Optimization for the Side-Member of an Aluminum Space Frame Vehicle (알루미늄 차체의 사이드멤버 충돌에너지 흡수성능 최적설계)

  • 김정호;김범진;허승진;김민수
    • Transactions of the Korean Society of Automotive Engineers
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    • v.12 no.5
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    • pp.94-100
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    • 2004
  • In order to improve the frontal crash performance of an Aluminum Space Frame Vehicle, this presents a systematic optimal design process to maximize the crush energy absorption capacity of side-members while satisfying the maximum displacement constraint. In this study, five design types are studied for selecting a good collapse initiator. Then, for the selected collapse initiator type, 7 design variables are defined to represent cross section shape, thickness and bead interval. The systematic optimization processor, R-INOPL uses DOE, RSM and numerical optimization techniques. R-INOPL uses only 14 analyses to solve the 7 design variable optimization problem the final design can improve 103.9% of the internal energy and reduce 13.9% of the maximum displacement.

A Study on the Grinding Characteristics of the Carbon Fiber Epoxy Composite Material Grinding Temperature (탄소섬유 에폭시 복합재료 연삭온도에 의한 연삭특성)

  • 한흥삼;이동주
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.9 no.6
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    • pp.65-70
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    • 2000
  • Although the net-shape molding of composites is generally recommended, molded composites frequently requires cutting or grinding due to the dimensional inaccuracy for precision machine elements. During the composite machining operations such as cutting and grinding, the temperature at the grinding area may increase beyond the allowed limit due to the low thermal conductivity of composites, which might degrade the matrix of composite. Therefore, in this work, the temperature at the grinding point during surface grinding of carbon fiber epoxy composite was measured. The grinding temperature and surface roughness were also measured to investigate the surface grinding characteristics of the composites. The experiments were performed both under dry and wet grinding conditions with respect to cutting speed, feed speed, depth of cut and stacking angle. From the experimental investigation, the optimal conditions for the composite surface grinding were suggested.

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Design Analysis and Field Try-out of Automotive Panel Dies (자동차 패널금형의 설계해석과 현장 트라이아웃)

  • 이종문;이한수;금영탁
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 1998.06a
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    • pp.25-32
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    • 1998
  • This study suggested the practical method which can reduce the lead time of the field trial and design of the dies. The virtual manufacturing, with the die design is evaluated by computer analysis, reveals the impropriety of a design before making dies. Three methods for reducing the die making process occupying over 60% of the automotive development are like fellows : First, the crack virtually adjusting the blank holding force and draw bead force with a computer simulation. Second, the parts which can not remove the forming defects in spite of the adjustment of forming process parameters need to modify the part geometry or punch temporary shape. Third, the simulation before trial, field trial, and field trial simulation can be used effectively in the die design.

A Study of Arc Modeling and Heat Input Distribution on the Surface during Torch Weaving in Gas Metal Arc Welding (가스 메탈 아크 용접에서 토치 위빙 중 아크 모델링 및 표면 입열 분포 해석에 관한 연구)

  • Kim, Yong-Jae;Rhee, Se-Hun
    • Journal of the Korean Society for Precision Engineering
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    • v.18 no.1
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    • pp.162-170
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    • 2001
  • In torch weaving in arc welding on V groove, the heat input distribution on groove surface is a main factor determining the bead shape and the weld quality with and without the weld defects such as undercut, overlap, etc. In this study, we calculate the heat input varying with the welding current, arc voltage, welding speed and the touch weaving condition using numerical method. And we investigate the heat input distribution on groove surface while applying the various grooves having 2 dimensional heat sources.

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Monitoring of Laser Material Processing Using Photodiodes (광 센서를 이용한 레이저 가공공정의 모니터링)

  • Park, Young-Hwan
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.10 no.3
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    • pp.515-520
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    • 2009
  • In this paper, the monitoring system was developed measuring the light signal emitted from the plasma in aluminum laser welding. Spectrum of plasma was measured using a spectrometer, and the photodiode was selected based on the spectrum analysis. The sensor signals for various welding conditions could be obtained, the characteristic of signal was closely related to the intensity and stability of plasma through mean value of signal and FFT analysis. The reason of signal fluctuation was behavior of plasma and keyhole and it was also connected with the surface bead shape of weld.

Effect of Anisotropy on the Wear Behavior of Age-Treated Maraging Steel Manufactured by LPBF (시효 열처리를 적용한 LPBF 제조된 마레이징 강의 마모 거동에 대한 이방성의 영향)

  • Seung On Lim;Se-Eun Shin
    • Journal of Powder Materials
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    • v.31 no.4
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    • pp.308-317
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    • 2024
  • Maraging steel has excellent mechanical properties resulting from the formation of precipitates within the matrix through aging treatment. Maraging steel fabricated by the laser powder bed fusion (LPBF) process is suitable for applications including precise components and optimized design. The anisotropic characteristic, which depends on the stacking direction, affects the mechanical properties. This study aimed to analyze the influence of anisotropy on the wear behavior of maraging steel after aging treatment. The features of additive manufacturing tended to disappear after heat treatment. However, some residual cellular and dendrite structures were observed. In the wear tests, a high wear rate was observed on the building direction plane for all counter materials. This is believed to be because the oxides formed on the wear track positively affected the wear characteristics; meanwhile, the bead shape in the stacking direction surface was vulnerable to wear, leading to significant wear.

Evaluation of Time-Temperature Integrators (TTIs) with Microorganism- Entrapped Microbeads Produced Using Homogenization and SPG Membrane Emulsification Techniques

  • Mijanur Rahman, A.T.M.;Lee, Seung Ju;Jung, Seung Won
    • Journal of Microbiology and Biotechnology
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    • v.25 no.12
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    • pp.2058-2071
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    • 2015
  • A comparative study was conducted to evaluate precision and accuracy in controlling the temperature dependence of encapsulated microbial time-temperature integrators (TTIs) developed using two different emulsification techniques. Weissela cibaria CIFP 009 cells, immobilized within 2% Na-alginate gel microbeads using homogenization (5,000, 7,000, and 10,000 rpm) and Shirasu porous glass (SPG) membrane technologies (10 μm), were applied to microbial TTIs. The prepared micobeads were characterized with respect to their size, size distribution, shape and morphology, entrapment efficiency, and bead production yield. Additionally, fermentation process parameters including growth rate were investigated. The TTI responses (changes in pH and titratable acidity (TA)) were evaluated as a function of temperature (20℃, 25℃, and 30℃). In comparison with conventional methods, SPG membrane technology was able not only to produce highly uniform, small-sized beads with the narrowest size distribution, but also the bead production yield was found to be nearly 3.0 to 4.5 times higher. However, among the TTIs produced using the homogenization technique, poor linearity (R2) in terms of TA was observed for the 5,000 and 7,000 rpm treatments. Consequently, microbeads produced by the SPG membrane and by homogenization at 10,000 rpm were selected for adjusting the temperature dependence. The Ea values of TTIs containing 0.5, 1.0, and 1.5 g microbeads, prepared by SPG membrane and conventional methods, were estimated to be 86.0, 83.5, and 76.6 kJ/mol, and 85.5, 73.5, and 62.2 kJ/mol, respectively. Therefore, microbial TTIs developed using SPG membrane technology are much more efficient in controlling temperature dependence.

Study on the Optimization Field Welding Conditions of Low Heat-Input Pluse MIG Welding Process for 5052 Aluminum Alloy Sheets (Al 5052 합금의 저입열 Pulse MIG 최적 현장 용접조건 산정에 관한 실험적 연구)

  • Kim, Jae-Seong;Lee, Young-Gi;An, Ju-Sun;Lee, Bo-Young
    • Journal of Welding and Joining
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    • v.29 no.1
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    • pp.80-84
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    • 2011
  • The weight reduction of the transportations has become an important technical subject Al and Al alloys, especially Al 5052 alloys have been being applied as door materials for automobile. One of the most widely known car weight-reduction methods is to use light and corrosion-resistant aluminum alloys. However, because of high electrical and thermal conductivity and a low melting point, it is difficult to obtain good weld quality when working with the aluminum alloys. Also, Pulse MIG welding is the typical aluminum welding process, but it is difficult to apply to the thin plate, because of melt-through and humping-bead. In order to enhance weld quality, welding parameters should be considered in optimizing the welding process. In this experiment, Al 5052 sheets were used as specimens, and these materials were welded by adopting new Cold Metal Transfer (CMT) pulse process. The proper welding conditions such as welding current, welding speed, torch angle $50^{\circ}$ and gap 0~1mm are determined by tensile test and bead shape. Through this study, range of welding current are confirmed from 100A to 120A. And, the range of welding speed is confirmed from 1.2m/min to 1.5m/min.

A Study on the Optimization for a V-groove GMA Welding Process Using a Dual Response Method (듀얼 반응표면법을 이용한 V-그루브 GMA 용접공정 최적화에 관한 연구)

  • Park, Hyoung-Jin;Ahn, Seung-Ho;Kang, Mun-Jin;Rhee, Se-Hun
    • Journal of Welding and Joining
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    • v.26 no.2
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    • pp.85-91
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    • 2008
  • In general, the quality of a welding process tends to vary with depending on the work environment or external disturbances. Hence, in order to achieve the desirable quality of welding, we should have the optimal welding condition that is not significantly affected by these changes in the environment or external disturbances. In this study, we used a dual response surface method in consideration of both the mean output variables and the standard deviation in order to optimize the V-groove arc welding process. The input variables for GMA welding process with the dual response surface are welding voltage, welding current and welding speed. The output variables are the welding quality function using the shape factor of bead geometry. First, we performed welding experiment on the interested area according to the central composite design. From the results obtained, we derived the regression model on the mean and standard deviation between the input and output variables of the welding process and then obtained the dual response surface. Finally, using the grid search method, we obtained the input variables that minimize the object function which led to the optimal V-groove arc welding process.

Distribution of Cold Receptor Transient Receptor Potential Melastatin 8-Immunopositive Axons in the Mouse Dental Pulp and Periodontal Tissue

  • Kim, Tae Heon;Lee, Jae Sik;Kim, Yun Sook;Bae, Yong Chul
    • International Journal of Oral Biology
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    • v.42 no.4
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    • pp.169-174
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    • 2017
  • Transient receptor potential melastatin 8 (TRPM8) plays a crucial role in innocuous cool sensation, acute cold pain and cold-induced hyperalgesia during pathologic conditions. To help understand TRPM8-mediated cold perception in the dental pulp and periodontal tissues, we examined the distribution of TRPM8-immunopositive (+) axons in molar and incisor pulp and periodontal tissues using transgenic mice expressing a genetically encoded axonal tracer in TRPM8+ neurons. In the radicular pulp of the molar teeth, a small number of TRPM8+ axons were observed. TRPM8+ axons branched frequently and extensively in the core of coronal pulp, forming a network in the peripheral pulp. Some TRPM8+ axons ascended between odontoblasts and were observed in the dentinal tubule. TRPM8+ axons were linear-shaped in the radicular pulp, whereas many TRPM8+ axons showed portions shaped like beads connected with thin axonal stands at the peripheral pulp. TRPM8 was densely expressed in the bead portions. In the incisor pulp, TRPM8+ axons were occasionally observed in the core of the coronal pulp and rarely observed at the peripheral pulp. TRPM8+ axons were occasionally observed and showed a linear shape rather than a bead-like appearance in the periodontal ligament and lamina propria of the gingival tissue. These findings, showing differential distribution of TRPM8+ axons between radicular and coronal portions of the molar pulp, between incisor and molar pulp, and between dental pulp and periodontal tissues, may reflect differential cold sensitivity in these regions.