• Title/Summary/Keyword: THICKNESS

Search Result 26,128, Processing Time 0.046 seconds

Prediction of the Film Thickness Variation through Film Insert Thermoforming (필름 인서트 열성형 시 필름 두께분포 예측)

  • Kim, G.Y.;Lee, K.O.;Kang, S.S.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
    • /
    • 2008.05a
    • /
    • pp.281-284
    • /
    • 2008
  • Film insert melding is one of the surface processes that enhances functional or aesthetic qualities of an existing product's surface. In general, film insert molding consists of three processes including thermoforming, trimming and injection molding. Thermoforming, which is the first process of film insert molding, is the most important process because the variation of film thickness has an effect on the mold design and process conditions for the subsequent processes, that are, trimming and injection molding. This study is focused on predicting the film thickness distribution through film insert thermoforming process using commercial FEM code. In order to describe rheological behavior of thermoplastic film (ABS), G'Sell's viscoelastic constitutive law was adopted. The numerical model of film insert thermoforming was established, and the simulation to predict film thickness distribution was performed. Comparison between the results of simulation and experiment was made to validate the proposed finite element analysis.

  • PDF

Dielectric Constant with $SiO_2$ thickness in Polycrystalline Si/ $SiO_2$II Si structure (다결정 Si/ $SiO_2$II Si 적층구조에서 $SiO_2$∥ 층의 두께에 따른 유전특성의 변화)

  • 송오성;이영민;이진우
    • Journal of the Korean institute of surface engineering
    • /
    • v.33 no.4
    • /
    • pp.217-221
    • /
    • 2000
  • The gate oxide thickness is becoming thinner and thinner in order to speed up the semiconductor CMOS devices. We have investigated very thin$ SiO_2$ gate oxide layers and found anomaly between the thickness determined with capacitance measurement and these obtained with cross-sectional high resolution transmission electron microscopy. The thicknesses difference of the two becomes important for the thickness of the oxide below 5nm. We propose that the variation of dielectric constant in thin oxide films cause the anomaly. We modeled the behavior as (equation omitted) and determined $\varepsilon_{bulk}$=3.9 and $\varepsilon_{int}$=-4.0. We predict that optimum $SiO_2$ gate oxide thickness may be $20\AA$ due to negative contribution of the interface dielectric constant. These new results have very important implication for designing the CMOS devices.s.

  • PDF

Design of top concrete slabs of composite space trusses

  • El-Sheikh, Ahmed
    • Structural Engineering and Mechanics
    • /
    • v.7 no.3
    • /
    • pp.319-330
    • /
    • 1999
  • The design of composite space trusses is a demanding task that involves taking several decisions on the truss depth, number of panels, member configuration, number of chord layers and concrete slab thickness and grade. The focus in this paper is on the design of top concrete slabs of composite space trusses, and in particular their thickness. Several effects must be considered in the process of designing the slab before an optimum thickness can be chosen. These effects include the inplane forces arising from shear interaction with the steel sub-truss and the flexural. and sheer effects of direct lateral slab loading. They also include a constructional consideration that the thickness must allow for sufficient cover and adequate space for placing the reinforcement. The work presented in this paper shows that the structural requirements on the concrete slab thickness are in many cases insignificant compared with the constructional requirements.

Factors Affecting on Quality Evaluation of Citrus unshiu Produced in Cheju (제주산 온주밀감의 품질평가에 미치는 요인)

  • 고정삼;양영택
    • Food Science and Preservation
    • /
    • v.1 no.1
    • /
    • pp.9-14
    • /
    • 1994
  • Soluble solids($^{\circ}$Brix), acid content and edible part ratio of Citrus unshiu collected at sorting Places in south Cheju area wee more lowered, and peel thickness was more thickened with increasing fruit size. Compared to early variety of Citurs unshiu(C. unshiu Miyakawa Mar), peel thickness of medium variety of Citurs unshiu(C. unshiu Hayashi Mar) was more thickened, and edible part ratio was more lowered with increasing fruit size. Soluble solids of medium variety of Citurs unshiu were lowered, and acid contents were increased compared to early variety. Processing properties for pressing concentrated juice was good for early variety of Citurs unshiu, especially on fruit diameter of 50-65mm. Soluble solids, acid contents and juice ratio were decreased with increasing peel thickness. The quality properties for fresh fruit with peel thickness had a good correlation on early variety of Citurs unshiu, and these data are supposed to be applied to the quality evaluation of Citurs unshiu produced in Cheju.

  • PDF

Thermal buckling resistance of simply supported FGM plates with parabolic-concave thickness variation

  • Benlahcen, Fouad;Belakhdar, Khalil;Sellami, Mohammed;Tounsi, Abdelouahed
    • Steel and Composite Structures
    • /
    • v.29 no.5
    • /
    • pp.591-602
    • /
    • 2018
  • This research presents an investigation on the thermal buckling resistance of FGM plates having parabolic-concave thickness variation exposed to uniform and gradient temperature change. An analytical formulation is derived and the governing differential equation of thermal stability is solved numerically using finite difference method. A specific function of thickness variation is introduced where it controls the parabolic variation intensity of the thickness without changing the original material volume. The results indicated that the loss ratio in buckling resistance is the same for any gradient temperature profile. Influencing geometrical and material parameters on the loss ratio in the thermal resistance buckling are investigated which may help in design guidelines of such complex structures.

Calculation of Average Thickness of film in Thermoforming by Simulation (시뮬레이션을 통한 열성형에서의 필름 평균두께 계산)

  • Soon-Young Lee;Sun-Kyoung Kim
    • Design & Manufacturing
    • /
    • v.17 no.4
    • /
    • pp.52-56
    • /
    • 2023
  • In this study, numerical simulation of the thermoforming process of PVC film material was performed using PAMForm. For this purpose, tensile tests were performed at various temperatures and the coefficients of the G'Sell model were obtained and used. As a result of the analysis, it was confirmed that the thickness decreased by up to 55% in the section where the film was in contact with the vertical direction and was greatly stretched. If the thickness is excessively thin, the part may become structurally weak, so in the thermoforming process, numerical simulation of the thickness in advance is expected to be helpful in successfully performing the process.

Partial-Thickness Tear of Supraspinatus and Infraspinatus Tendon Revisited: Based on MR Findings (극상건과 극하건 부분 파열의 재고찰: MR 소견을 바탕으로)

  • Sinhye Song;Seul Ki Lee;Jee-Young Kim
    • Journal of the Korean Society of Radiology
    • /
    • v.82 no.6
    • /
    • pp.1366-1387
    • /
    • 2021
  • The interpretation of MRI of partial-thickness rotator cuff tears can be challenging. This review describes the anatomic considerations for diagnosing partial-thickness tears, especially supraspinatus and infraspinatus tendon and summarizes the classification of partial-thickness rotator cuff tears, as well as provides an overview on partial-thickness tears with delamination.

Improvement of shear deformation by controlling reduction per a rolling pass during asymmetrical cold rolling in AA 5052 (AA5052 판재의 비대칭 냉간압연 시 압연 패스당 압하율 제어에 의한 전단 변형 향상)

  • Kang, H.G.;Han, Y.H.;Huh, M.Y.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
    • /
    • 2007.05a
    • /
    • pp.226-228
    • /
    • 2007
  • During asymmetrical cold rolling in AA 5052 sheet a reduction per a rolling pass was varied to investigate the effect of the ratio of the contact length between the roll and sample ($l_c$) to the sheet thickness (d) on the formation of shear textures. In order to intensify the shear deformation during asymmetrical rolling, AA 5052 sheet was asymmetrically cold rolled without lubrication by using different roll velocities of upper and lower rolls. Asymmetrical rolling with $l_c$/d=1.8 led to the formation of texture gradients throughout the sheet thickness in which the outer thickness layers depicted shear textures and the center thickness layers displayed a rolling texture. Asymmetrical rolling with $l_c$/d=3.1 gave rise to the formation of shear textures in the whole through-thickness layer. The strain states associated with asymmetrical rolling were investigated by the finite element method (FEM) simulation. FEM results indicated that the evolution of deformation texture in a thickness layer is strongly governed by integrated values of strain rates and along the streamline in the roll gap.

  • PDF

An Experimental Study of the Nozzle Lip Thickness Effect on Supersonic Jet Screech Tones

  • Aoki Toshiyuki;Kweon Yong-Hun;Miyazato Yoshiaki;Kim Heuy-Dong;Setoguchi Toshiaki
    • Journal of Mechanical Science and Technology
    • /
    • v.20 no.4
    • /
    • pp.522-532
    • /
    • 2006
  • It is well known that screech tones of supersonic jet are generated by a feedback loop driven by the instability waves. Near the nozzle lip where the supersonic jet mixing layer is receptive to external excitation, acoustic disturbances impinging on this area excite the instability waves. This fact implies that the nozzle lip thickness can influence the screech tones of supersonic jet. The objective of the present study is to experimentally investigate the effect of nozzle-lip thickness on screech tones of supersonic jets issuing from a convergent-divergent nozzle. A baffle plate was installed at the nozzle exit to change the nozzle-lip thickness. Detailed acoustic measurement and flow visualization were made to specify the screech tones. The results obtained obviously show that nozzle-lip thickness significantly affects the screech tones of supersonic jet, strongly depending on whether the jet at the nozzle exit is over-expanded or under-expanded.

Influence of slice thickness of computed tomography and type of rapid protyping on the accuracy of 3-dimensional medical model (CT절편두께와 RP방식이 3차원 의학모델 정확도에 미치는 영향에 대한 연구)

  • Um Ki-Doo;Lee Byung-Do
    • Imaging Science in Dentistry
    • /
    • v.34 no.1
    • /
    • pp.13-18
    • /
    • 2004
  • Purpose : This study was to evaluate the influence of slice thickness of computed tomography (CT) and rapid protyping (RP) type on the accuracy of 3-dimensional medical model. Materials and Methods: Transaxial CT data of human dry skull were taken from multi-detector spiral CT. Slice thickness were 1, 2, 3 and 4 mm respectively. Three-dimensional image model reconstruction using 3-D visualization medical software (V-works /sup TM/ 3.0) and RP model fabrications were followed. 2-RP models were 3D printing (Z402, Z Corp., Burlington, USA) and Stereolithographic Apparatus model. Linear measurements of anatomical landmarks on dry skull, 3-D image model, and 2-RP models were done and compared according to slice thickness and RP model type. Results: There were relative error percentage in absolute value of 0.97, 1.98,3.83 between linear measurements of dry skull and image models of 1, 2, 3 mm slice thickness respectively. There was relative error percentage in absolute value of 0.79 between linear measurements of dry skull and SLA model. There was relative error difference in absolute value of 2.52 between linear measurements of dry skull and 3D printing model. Conclusion: These results indicated that 3-dimensional image model of thin slice thickness and stereolithographic RP model showed relative high accuracy.

  • PDF