• Proceedings of the Korea Information Processing Society Conference
• /
• 2021.11a
• /
• pp.731-732
• /
• 2021

인쇄 적성 증진제는 식품용 3D 프린팅에서 겔화 소재의 인쇄 적성을 향상시키는 요소 중 하나이다. 이 때, 인쇄 적성 증진제의 평가는 전단응력을 받을 때 일어나는 변형의 정도를 나타내는 전단탄성률 기반으로 한다. 그러나, 전단 탄성률 측정은 식품 원재료의 다양함으로 인해 소재별로 측정하는데 많은 시간과 비용이 소요되는 단점이 있다. 이에 본 연구에서는 FCN과 RNN을 사용하여 전단탄성률을 예측하는 신경망 설계를 제안함으로써 인쇄 적성 증진제의 전단탄성률을 측정하는 시간과 비용을 절감하고자 한다.

• The Journal of the Acoustical Society of Korea
• /
• v.17 no.8
• /
• pp.58-63
• /
• 1998

저주파 영역의 음파의 투과속도 측정에 기존의 펄스에코방법이나 투과법 (transmission method)가 이용되는 경우, 탐촉자 및 시편의 크기, 시편과 탐촉자 사이의 거 리가 사용하는 음파의 주파수가 작아질수록 대형화되어 측정에 어려움을 나타내게 된다. 따 라서 본 연구에서는 고분자 재료의 음향특성을 평가할 수 있는 간단한 방법으로써 고분자 재료의 주파수에 따른 동적 탄성률(dynamic modulus)을 시간-온도 중첩의 원리를 이용하여 측정하고, 고분자 내에서 저주파 영역의 음파의 전달 속도와 주파수에 따른 탄성율(elastic modulus), 전단 탄성률(shear modulus) 그리고 밀도의 관계식으로부터 음속을 측정하였다. 실험결과 주파수가 증가함에 따라 고분자 재료의 동적 탄성률이 증가하였으며, 음속도 주파 수에 따라 증가하였다. 본 연구에서 사용한 폴리우레탄 재료의 음속은 100Hz∼10kHz영역에 서 약1500m/sec에서 3000m/sec를 나타내었다.

• Journal of Adhesion and Interface
• /
• v.5 no.1
• /
• pp.21-28
• /
• 2004

In this work, glass fiber/nylon 6 and woven glass fiber/nylon 6 composites have been fabricated using glass fiber reinforcements sized with 3-chloropropyltrimethoxysilane(CTMS) having a chloropropyl organo-functional group in the molecular chain end. The interfacial shear strength of glass fiber/nylon 6 composite was measured using a single fiber microbonding test and the interlaminar shear strength and the storage modulus of woven glass fabric/nylon 6 composites were measured using a short-warn shear test and a dynamic mechanical analysis, respectively, informing the effect of the concentration of CTMS on the properties. With increasing CTMS concentration, the interfacial properties of the composites were improved. The results on the interfacial shear strength, interlaminar shear strength, interlaminar failure pattern, and storage modulus with varying the CTMS concentration agree with each other.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.29 no.4
• /
• pp.293-299
• /
• 2016

In this paper, a projection method is introduced which is used in topology design optimization. In the projection method, each active design variable is projected onto the design domain depending on the shape and size of the projection functions, and the finite element under this projection receives a solid material. Furthermore, the size of the projection function defines the minimum length scale of the structural members. Therefore, a designer can easily apply design constraints without complicated post-processing procedure. In addition, the projection method can be combined with the homogenization theory, and applied to material design problem for composite materials. Topology design optimization for the unit-cell of the periodic structures can maximize the effective material properties, which yields the optimal material distribution with maximum bulk or shear moduli under a given volume fraction.

• The Korean Journal of Rheology
• /
• v.3 no.2
• /
• pp.175-185
• /
• 1991

Sodium octylbenzenesulfonate(SOBS)와 sodium dodecylbenzenesulfonate(SDBS)를 폴리프로필렌(PP) 용융액에 각각 균일하게 서로 다른 함량으로 섞어 넣은 후에 용융압착법 으로 PP 필름을 제조하였다. 저장 점성도(η＇) 저장탄성률(G＇) 및 손실 탄성률(G＂)을 진 동식 레오미터를 사용하여 170~195$^{\circ}C$에서 측정하였다. 실험온도 범위내에서 첨가제를 함유 한 PP와 순PPrks에 Cole-Cole 플롯(G＇에 대한 G＂의 log-log 플롯)에는 차이가 없었다. 그러나 광범위한 전단속도에서 SOBS의 첨가량이 8%를 넘어서면서 η＇과 G＇은 증가하였 다. 이러한 현상은 PP 중에서의 첨가제의 응집효과로 설명되었으며 이것은 SOBS와 SDBS 를 함유하는 PP 필름의 시차 주사열량법 및 주사전자 현미경 관찰결과로 확인되었다. SDBS를 8% 미만 함유하는 PP로부터 섬유의 용융방사가 가능하였으나 SDBS3% 이상 함 유PP 방사섬유는 연신 과정중에 섬유의 절단이 이따금 일어났다. PP 기질내에 있어서의 SDBS의 뜨거운 물에대한 견뢰성을 SDBS와 C. I. Basic blue 41사이의 이온결합 형성 거동 에 바탕을 두어 가시분광법에 의하여 검토하였다.

• Korean Journal of Food Science and Technology
• /
• v.51 no.4
• /
• pp.330-335
• /
• 2019

The aim of this study was to investigate the rheological properties of arabinogalactans (AGs) solution isolated from moth bean (MB), navy bean (NB), and soybean (SB) including monosaccharide compositions, intrinsic viscosity, steady shear and dynamic shear rheological properties. The major monosaccharides in MB, NB, and SB were arabinose (64.8, 51.4, and 42.6%) and galactose (13.4, 19.6, and 46.2%). The yield stresses for 5% (w/v) NB and 2.5% (w/v) SB solutions were assessed as 2.10 Pa and 1.98 Pa, respectively, but in case of MB solution, it was observed to be negligible. While 5% MB solution showed rheopectic property, 5% NB and SB solutions showed thixotropic properties. As a result of frequency sweep experiment, the G' values in 2.5% MB and NB were larger than the G" value showed but 2.5% SB exhibited G" value greater than G'. These results would be useful for future application as a food additive in the food industry.

• Korean Journal of Food Science and Technology
• /
• v.27 no.5
• /
• pp.799-806
• /
• 1995

The steady shear and small amplitude oscillatory dynamic rheological properties of citrus pectin $([\eta]=3.75\;dL/g)$ were characterized for a wide range of pectin concentrations $({\sim}6%)$. The typical power-law flow was observed above 2.0% concentration, and the shear rate dependence of viscosity increased with pectin concentration. The transition from dilute to concentrated regime, determined from the double logarithmic plot of ${\eta_{sp.o}}\;vs\;C[\eta]$, occurred at a critical coil overlap parameter $C^{*}[\eta]\approx4.0$, at which ${\eta_{sp.o}}$ corresponded to approximately 10.0. The slopes of ${\eta_{sp.o}}\;vs\;C[\eta]$, at $C[\eta]\;at\;C[\eta]C^{*}[\eta]$were 1.1 and 4.5, respectively. The steady viscosity $(\eta)$ displayed a good superposition at ${\eta}/{\eta}_o\;vs\;{\gamma}/{\gamma}_{0.8}$ relation with an exception of high concentration (6%), which arised from the significant deviation of flow behavior index (n values of $\eta_{a}=K\gamma^{n-1}$) at high concentration. Dynamic measurements showed that the loss modulus $(G^{\prime\prime})$ was much higher than the storage modulus $(G^\prime)$for all concentrations studied, indicating predominant viscoelastic liquid-like behavior of pectin solutions. The frequency dependence of $G^\prime$ was higher than that of $G^\prime\prime$ at the same concentration, whose trend was more pronounced with decreasing pectin concentration. The shear viscosity $(\eta)$ was almost identical to the complex viscosity $(\eta^{*})$ at low concentration, following the Cox-Merz rule, but they became increasingly different at high concentration.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.22 no.9
• /
• pp.837-844
• /
• 2012

We considered an approach in terms of materials for improvement of insulation performance of vehicle rubber hoses. Ethylene propylene rubber(EPDM) for heater hoses in cooling system and acrylic rubber(AR) for intercooler hose in intake system were chosen for mixing for the vibration and noise performance. We modified EPDM and AR through changing compound of base polymer, reinforcement fillers and additives. Dynamic mechanical analysis(DMA) was used to measure viscoelastic properties such as shear modulus and loss factor($tan{\delta}$). Vehicle acceleration test was also conducted to observe indoor changes in insulation performance of hoses.

• The Korean Journal of Rheology
• /
• v.10 no.1
• /
• pp.7-13
• /
• 1998

중량 평균 분자량이 1.22$\times$106이고 다분산도가 8.90이며 수분과 아밀로오스 함량이 각각 9.35%, 27%인 도토리 전분에 sucrose를 첨가하여 동적 유변학적 특성에 대한 온도와 농도의존성을 고찰하였다. AS(acorn starch)-sucrose 계의 점도는 전단속도가 증가하면 감 소하는 전단담화 현상을 나타내며 sucrose 농도가 증가할수록 점도가 증가하였고, Casson 식에 의해 얻어진 항복치는 sucrose 농도가 증가하면 증가하였다. 저장영률과 손실영률은 sucrose 농도가 증가하면 단일하게 증가하였고 손실 탄성률은 온도가 증가하면 감소하였다. DSC 측정자료를 zipper model에 적용시켜 본 결과 sucrose 농도가 증가할수록 zipper의 수 와 junc-tion zone의 수는 증가했으며 크기는 감소하였다. Sucrose는 전분과 수소결합을 형 성하여 용액내에서 가소제처럼 거동함을 알수있었다.

• Polymer(Korea)
• /
• v.27 no.3
• /
• pp.189-194
• /
• 2003

Interfacial evaluation, damage sensing and cure monitoring of single carbon fiber/thermo setting composite with different curing processes were investigated using electro-micromechanical test. After curing, the residual stress was monitored by measurement of electrical resistance and then compared to various curing processes. In thermal curing case, matrix tensile strength, modulus and interfacial shear strength were higher than those of ultraviolet curing case. The shrinkage measured during thermal curing occurred significantly by matrix shrinkage and residual stress due to the difference in thermal expansion coefficient. The apparent modulus measured in the thermal curing indicated that mechanical and interfacial properties were highly improved. The reaching time to the same stress of thermal curing was faster than that of UV curing case.