• Title/Summary/Keyword: RTV

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Study on Rapid Manufacturing of 3D Functional Parts Combining VLM-ST Process and Its RT Technology (단속형 가변적층 쾌속조형공정과 쾌속툴링 기술을 이용한 쾌속 3차원 기능성 제품 개발에 관한 연구)

  • 안동규;이상호;김기돈;양동열
    • Transactions of Materials Processing
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    • v.11 no.4
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    • pp.323-331
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    • 2002
  • The combination of rapid prototyping(RP) and rapid tooling(RT) has a potential for rapid manufacturing of three-dimensional parts. In the present study, a new RP system transfer type Variable Lamination Manufacturing using Expandable Polystyrene Foam (VLM-ST), is proposed to fabricate net shapes of three-dimensional prototypes. Various three-dimensional parts, such as a knob shape and a human head shape, are manufactured by the VLM-ST apparatus. In addition, a new rapid tooling technology, which utilizes a room temperature vulcanizing (RTV) molding technique and a triple reverse process technique, is proposed to manufacture net shapes of three-dimensional plastic parts using the prototypes of VLM-ST. A plastic part of the knob shape is produced by the proposed RT technology. The combination of the proposed RP and RT enables the manufacture of a plastic knob within two days.

Spatial Distribution of Temperature Change in a R-TV Rubber for Diagnostic Ultrasonic Imaging System (초음파 영상 진단기의 발진모드별 R-TV 고무 내부의 온도변화 분포)

  • Jho Moon Jae;Kim Yong Tae;Yun Yong Hyeon
    • Proceedings of the Acoustical Society of Korea Conference
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    • autumn
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    • pp.349-350
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    • 2004
  • 매질 내부로 전파하는 초음파는 점성손실(viscous loss), 열전도 손실(heat conduction loss) 둥 다양한 상호작용을 통해 흡수되어 열에너지로 변환되기 때문에 매질 내의 온도 변화를 발생시킨다. 본 논문에서는 RTV 고무 내부에 47 개의 열전대를 장착하여 초음파 영상 진단기로부터 발생되는 초음파 음장에 따른 각 열전대의 채널별 온도변화의 측정결과를 제시하였다.

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Adhesion Behaviors of Semiconductive-Insulation Interfaced Liquid Silicone Rubber for EHV Cable Accessory (초고압 접속재용 반도전-절연체 액상실리콘 계면의 접착거동)

  • Yoon, Seung-Hoon;Kim, Hyun-Seok;Kim, Ji-Hwan;Lee, Jung-Hee
    • Proceedings of the KIEE Conference
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    • 2003.10a
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    • pp.123-127
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    • 2003
  • 액상실리콘으로 이루어진 초고압전력케이블용 프리몰드 접속재의 반도전-절연체 계면접합체를 다양한 제조조건과 조합별로 제조하여 계면접착력에 대한 영향을 검토하였다. 후가교적용 시 계면접착력이 강화되며 grade조합에 따른 특성차이가 존재하였다. 하지만 고온 장시간의 후가교 조건에서는 계면간의 화학적 결합력의 저하로 인해 오히려 접착력이 낮아지기도 하였다. 절연 RTV와의 계면접착성은 S-1재료가, 절연 LSR의 경우에는 S-3 재료가 가장 우수하였으며 도전안정성 측면에서도 S-3 재료가 상대적으로 유리하였다. 매입형 전극체를 제조하여 절연파괴거동을 연구한 결과 계면접착성과의 직접적인 상관관계는 크지 않음을 알 수 있었다.

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Three-Dimensional Net Shaping Combining $VLM-_{ST}$ and the Triple Reverse Rapid Tooling ($VLM-_{ST}$ 공정과 삼단역전 쾌속 툴링 공정을 이용한 3차원 제품 정형가공에 관한 연구)

  • 안동규;이상호;양동열
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • 2003.04a
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    • pp.428-432
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    • 2003
  • The technical combination of RP and RT has a potential for rapid manufacturing of three-dimensional parts. In the present work a new RP system, $VLM-_{ST}$, is proposed to manufacture net shapes of 3D prototypes. ㅁ human head shape and a kob shape are manufactured by the $VLM-_{ST}$ apparatus. In addition, a new RT technology, which utilizes a RTV molding technique and a triple reverse process technique, is proposed to manufacture net shapes of 3D plastic parts using prototypes of $VLM-_{ST}$. A plastic part of the knob shape os produced by the proposed RT technology. The combination of the proposed RP and RT enables the manufacturing of a plastic knob within two days.

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Adhesives and Sealants Used in Machinery and Equipment Assembly, Maintain and Repair

  • Zhai, Haichao;Li, Yinbai;Lin, Xinsong
    • Journal of Adhesion and Interface
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    • v.3 no.1
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    • pp.30-36
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    • 2002
  • In this paper, some idea about the use of Metal and ceramic filled epoxy adhesive, Anaerobic adhesive and RTV silicone in the assembly, maintain and repair of machinery and equipment is given. Many examples which have been successfully used in Chinese industry are introduced: ${\bullet}$ Wear, Abrasion, Corrosion/Erosion Resistance and Metal Rebuilding Worn shafts, Scored Hydraulic Ram, Bearing Housings, Slurry Pumps (Bodies & Impellers), Slide-ways, Heat Exchangers, Cracked Castings and Molds. Leaking Pipes and Tanks. ${\bullet}$ Locking and Retaining Thread, Bearing, Keyways, Bolts, Nuts, Studs, Gears, Collars, Motors. ${\bullet}$ Scaling and Gasketing Flanges, Pipe Joints, Machined surfaces.

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The effect of a titanium socket with a zirconia abutment on screw loosening after thermocycling in an internally connected implant: a preliminary study (내부연결 임플란트용 타이타늄 소켓을 이용한 지르코니아 지대주에서 열순환이 나사풀림에 미치는 영향: 예비연구)

  • Kyung, Kyu-Young;Cha, Hyun-Suk;Lee, Joo-Hee
    • Journal of Dental Rehabilitation and Applied Science
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    • v.33 no.2
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    • pp.114-118
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    • 2017
  • Purpose: The aim of this study was to investigate the effects of a titanium component for the zirconia abutment in the internal connection implant system on screw loosening under thermocycling conditions. Materials and Methods: Internal connection titanium abutments and external connection zirconia abutments with titanium sockets were connected respectively to screw-shaped internal connection type titanium implants with 30 Ncm tightening. These implant-screw-abutment assemblies were divided into two groups of five specimens each; titanium abutments as control and zirconia abutments with titanium sockets as experimental group. The specimens were subjected to 2,000 thermocycles in water baths at $5^{\circ}C$ and $55^{\circ}C$, with 60 seconds of immersion at each temperature. The removal torque values (RTVs) of the abutment screws of the specimen were measured before and after thermocycling. RTVs pre- and post-thermocycling were investigated in statistics. Results: There was not screw loosening identified by tactile and visual inspection in any of the specimens during or after thermocycling. The mean RTV difference for the control group and the experimental group were $-1.34{\pm}2.53Ncm$ and $-1.26{\pm}2.06Ncm$, respectively. Statistical analysis using an independent t-test revealed that no significant differences were found in the mean RTV difference of the groups (P > 0.05). Conclusion: Within the limitations of this in vitro study, the titanium socket for the zirconia abutment did not show a significant effect on screw loosening under thermal stress compared to the titanium abutment in the internal connection implant.

Signal-Characteristic Analysis with Respect to Backing Material of PVDF-Based High-Frequency Ultrasound for Photoacoustic Microscopy (광음향 현미경을 위한 PVDF 기반 고주파수 초음파 변환기의 흡음층 소재에 따른 신호 특성 분석)

  • Lee, Junsu;Chang, Jin Ho
    • Journal of the Korean Society for Nondestructive Testing
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    • v.35 no.2
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    • pp.112-119
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    • 2015
  • Photoacoustic microscopy is capable of providing high-resolution molecular images, and its spatial resolution is typically determined by ultrasonic transducers used to receive the photoacoustic signals. Therefore, ultrasonic transducers for photoacoustic microscopy (PAM) should have a high operating frequency, broad bandwidth, and high signal-reception efficiency. Polyvinylidene fluoride (PVDF) is a suitable material. To take full advantage of this material, the selection of the backing material is crucial, as it influences the center frequency and bandwidth of the transducer. Therefore, we experimentally determined the most suitable backing material among EPO-TEK 301, E-Solder 3022, and RTV. For this, three PVDF high-frequency single-element transducers were fabricated with each backing material. The center frequency and -6 dB bandwidth of each transducer were ascertained by a pulse-echo test. The spatial resolution of each transducer was examined using wire-target images. The experimental results indicated that EPO-TEK 301 is the most suitable backing material for a PAM transducer. This material provides the highest signal magnitude and a reasonable bandwidth because a large portion of the energy propagates toward the front medium, and the PVDF resonates in the half-wave mode.

All-Solid-State Ion-Selective Electrodes With Organic Solvents Soluble Conducting Polymer for Chemical Sensor (화학센서를 위한 유기 용해성이 좋은 도전성 고분자가 포함된 전체 고체상태 이온 선택성 전극에 대한 연구)

  • Kim, Joong-Il;Park, Jong-Ho;Jang, Won;Heo, Min;Na, Young-Ho;Shin, Jae-Ho;Kim, Do-Young;Um, Hwan-Sub;Lee, Sang-Woo;Kim, In-Tae
    • Journal of the Korean Applied Science and Technology
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    • v.30 no.2
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    • pp.258-263
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    • 2013
  • New conducting polymers containing heterocyclic ring with carbazole, EDOT and benzobisthiazole were synthesized and characterized by organic spectroscopic methods. Potentiometric ion-selective membrane electrodes (ISMEs) have been extensively used for ion analysis in clinical, environmental, and industeial fields owing to its wide response range (4 to 7 orders of magnitude), no effect of sample turbidity, fast response time, and ease of miniaturization. Considerable attention has been given to alternative use of room temperature vulcanizing (RTV)-type silicone rubber(SR) owing to its strong adhesion and high thermal durability. Unfortunately, the high membrane resistance of SR-based (ISMs)(2 to 3 higher orders of magnitude compared to those of poly(vinyl chloride)(PVC)-based ones) has significantly restricted its application. Herein we demonstrate a new method to reduce membrane resistance via addition of new conducting polymer into the SR-based ISMs.

A Study on the Surface Roughness and Initial Stability of Various Dental Implants (수종 임플랜트의 표면 거칠기와 초기안정성에 관한 연구)

  • Cho, Dong-Hoon;Lim, Ju-Hwan
    • Journal of Dental Rehabilitation and Applied Science
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    • v.16 no.3
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    • pp.197-210
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    • 2000
  • Surface roughness is one of implant surface topography and it's found that surface roughness characterizations, such as surface energy, oxide layer thickness and its chemical composition, are closely correlated if the roughness is changed. Several studies showed the importance of analyzing surface structure so the surface structure of thread implant was analyzed to measure the implant quality exactly. In this study, surface roughness of 4 implants - MK $II^{(R)}$(Nobel Biocare), $RBM^{(R)}$(Life-Core, USA), $Osseotite^{(R)}$(3i, USA), $TPS^{(R)}$(Life-Core, USA) - were measured using $Accura^{(R)}$ and 40 implants were installed into 4 sets of ten bovine ribs based on the parameters from the measurements. From this test, the following conclusions for the initial stability were drawn by measuring and comparing RFA, Periotest Value (PTV), Removal Torgue Value (RTV). 1. $R_a$ value in surface roughness measurement was increasing by the order of $MKII^{(R)}$, $Osseotite^{(R)}$, $RBM^{(R)}$, $TPS^{(R)}$ and $R_q$ value was the same order. 2. $R_q$ value in each section was observed to increase by the order of $MKII^{(R)}$, $Osseotite^{(R)}$, $RBM^{(R)}$, $TPS^{(R)}$ in top and $MKII^{(R)}$, $RBM^{(R)}$, $Osseotite^{(R)}$, $TPS^{(R)}$ in mid-section but the value of $MKII^{(R)}$ bottom was the lowest, followed by $Osseotite^{(R)}$, $RBM^{(R)}$ and $TPS^{(R)}$. 3. RFA increased by the order of $RBM^{(R)}$(7042Hz), $MKII^{(R)}$(7047Hz), $Osseotite^{(R)}$(7076Hz), $TPS^{(R)}$(7168Hz) and there was no significance between each group. 4. PTV was increasing by the order of $MKII^{(R)}$(-1.62), $TPS^{(R)}$(-1.92), $Osseotite^{(R)}$ & $RBM^{(R)}$(-2.08) and there was no significance, either. 5. Removal torque in RTV measurement showed the increasing order of $MKII^{(R)}(5.31kgf{\cdot}cm)$, $Oeeotite^{(R)}(5.71kgf{\cdot}cm)$, $TPS^{(R)}(5.92kgf{\cdot}cm)$ and $RBM^{(R)}(7.24kgf{\cdot}cm)$ and there was no significance among groups. Above observations explains that surface roughness does not make any impact on the initial stability of implants installation.

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Effect of ,Shear Stress on the Viscosity and Electrical Conductivity for the Metal-Filled Composite Materials (금속입자 충전 복합재료의 전단응력에 따른 점도 및 전기 전도도 변화)

  • Lee, Geon-Woong;Choi, Dong-uk;Lee, Sang-Soo;Kim, Jun-Kyung;Park, Min
    • Polymer(Korea)
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    • v.26 no.5
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    • pp.644-652
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    • 2002
  • This study aims at developing the conductive pastes consisting of room temperature vulcanizing (RTV) silicone and metal powder as matrix and filler, respectively. Electrical and rheological properties of metal - filled polymer composites are in general strongly affected by particle shape, side and dispersion state of the filler. In highly filled systems, particles tend to form very complex agglomerated structure which is easily changed when subjected to shear deformation. And the breakdown of agglomerated particles due to shear usually leads to the change of electrical conductivity of the composite. In this study, the effect of particle size and dispersion state of filler on the electrical conductivity of the composites are investigated to offer the selection criteria of conductive filler by measuring the rheological properties of uncured composites and the electrical conductivity of the cured composites. It was found that the type of metal filler systematically affected the rheological property, the susceptibility to shear and the degree of change of electrical conductivity of the composite. The effect of shear on the properties is more conspicuous in the composites containing large particle, indicating that both rheological and electrical properties can be improved by controlling the dispersion state at a given filler content.