• Title/Summary/Keyword: contact angle test

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Automatic Test Method of Sizing Degree by Analysis of Liquid Penetration and its Surface Behavior (액체 침투 특성과 표면 거동 분석을 이용한 사이즈도 자동측정법)

  • Lee, Ji-Young;Kim, Gyung-Chul;Kim, Chul-Hwan;Sheikh, M.I.;Park, Hyun-Jin;Kim, Sung-Ho;Sim, Sung-Woong;Cho, Hu-Seung
    • Journal of Korea Technical Association of The Pulp and Paper Industry
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    • v.44 no.2
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    • pp.18-28
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    • 2012
  • This study was to develop a novel automatic system for measuring St$\ddot{o}$ckigt sizing degree and contact angle at a time. The conventional methods to measure sizing degree had serious problems in obtaining significant differences according to different dosages of a sizing agent, and moreover they disclosed unique limitation due to liquid types used and tester's subjectivity. However, the newly developed system could get reproducible results through total automation of all procedures including liquid dropping, image acquisition and measurement of both St$\ddot{o}$ckigt sizing degree and contact angle. For the St$\ddot{o}$ckigt sizing test, the automatic system could measure sizing degree with more definite differences according to different dosage of AKD, compared to the conventional method. For the contact angle test, the automatic system showed a similar trend to the conventional method but had smaller contact angles due to distortion of an image focus by a sheet curl than the conventional testing machine. The problem from the image out of focus due to specimen curl will be overcome with adopting a new specimen holder for the future system.

Numerical Study of Heat Transfer Associated with Droplet Impact (액적 충돌에 동반된 열전달에 관한 수치적 연구)

  • Kim, Sung-Il;Son, Gi-Hun
    • Proceedings of the KSME Conference
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    • 2004.04a
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    • pp.1897-1902
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    • 2004
  • Numerical analysis of the heat transfer associated with droplet impact on a hot solid surface is performed by solving the mass, momentum and energy equations for the liquid-gas region. The deformed droplet shape is tracked by a level set method which is modified to achieve volume conservation during the whole calculation procedure and to include the effect of contact angle at the wall. The numerical method is validated through test calculations for the cases reported in the literature. Based on the numerical results, the effects of advancing/receding contact angle, impact velocity and droplet size on the heat transfer during droplet impact are quantified.

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Shear Behavior of Plasma-treated Graphite/Epoxy Laminated Composites Using Oxygen Gas (산소 플라즈마로 표면처리된 탄소섬유/에폭시 적층복합재의 전단거동)

  • Kim, Min-Ho;Rhee, Kyong-Yop;Paik, Young-Nam;Jung, Dong-Ho;Kim, Hyeon-Ju
    • Journal of the Korean Society for Precision Engineering
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    • v.25 no.9
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    • pp.103-108
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    • 2008
  • In-plane shear tests were performed to investigate the shear property change of FRP by plasma modification. Graphite/epoxy prepreg was used as a test material and plasma source was a microwave (2.4GHz) type. Plasma was induced by oxygen gas and its flow rate was kept $4{\sim}5$sccm with low vacuum state of $10^{-3}$ Torr. Prepreg was stacked unidirectionally ($[0^0]_8$) after plasma modification. Wettability was determined by measuring a contact angle. The results showed that the contact angle was decreased from $86^0$ to $45^0$ after plasma modification. Shear strength was also improved by ${\sim}10%$. SEM examination was made on the fracture surface and functional group produced by the plasma modification was investigated by XPS.

Evaluation of Reliability of Automatic System for Measuring Sizing Degree by Basis Weight Variation of Paper (종이 평량의 차이에 따른 자동 사이즈도 측정 시스템의 신뢰성 평가)

  • Lee, Ji-Young;Kim, Chul-Hwan;Lee, Ji-Young;Nam, Hye-Gyeong;Lee, Gyeong-Sun;Jo, Hu-Seung;Park, Hyung-Hun
    • Journal of Korea Technical Association of The Pulp and Paper Industry
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    • v.46 no.3
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    • pp.11-19
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    • 2014
  • Reliability of the novel automatic system capable of measuring both St$\ddot{o}$ckigt sizing degree and contact angle at a time was evaluated through the calculation of its repeatability and reproducibility based on TAPPI Standard Method T 1200. As the basis weight of paper specimen increased, the repeatability and reproducibility of the automatic system became more improved than those from Hercules sizing test and contact angle test designated on TAPPI Standard Method T 530 and T 558. The more improved repeatability and reproducibility implies that a single tester can obtain the similar results under similar test conditions in spite of repetitive testing using the automatic system, and likewise that multiple testers can respectively reproduce similar data without big variation from the same paper specimen using the automatic system. In conclusion, this study is greatly meaningful in having developed the world's first automatic system to measure both St$\ddot{o}$ckigt sizing degree and contact angle simultaneously with excellent repeatability and reproducibility.

CONTACT PRESSURE DISTRIBUTION OF RADIAL TIRE IN MOTION WITH CAMBER ANGLE

  • Kim, Seok-Nam;Kondo, Kyohei;Akasaka, Takashi
    • Proceedings of the KSME Conference
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    • 2000.11a
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    • pp.387-394
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    • 2000
  • Theoretical and experimental study is conducted on the contact pressure distribution of a radial tire in motion under various camber angles. Tire construction is modelled by a spring bedded elastic ring, consisted of sidewall springs and a composite belt ring. The contact area is assumed to be a trapezoidal shape varying with camber angles and weighted load. The basic equation in a quasi-static form is derived for the deformation of a running belt with a constant velocity by the aid of Lagrange-Euler transformation. Galerkin's method and stepwise calculation are applied for solving the basic equation and the mechanical boundary condition along both sides of the contact belt part subjected to shearing forces transmitted from the sidewall spring. Experimental results on the contact pressure, measured by pressure sensors embedded in the surface of the drum tester, correspond well with the calculated ones for the test tire under various camber angles, running velocities and weighted loads. These results indicate that a buckling phenomenon of the contact belt in the widthwise direction occurs due to the effect of camber angle.

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Experimental Study on the Contact Force of Rubber Seals for a Ball Bearing (베어링 용 고무시일의 접촉력에 관한 실험적 연구)

  • 전인기;심우전;최인혁;김청균
    • Tribology and Lubricants
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    • v.9 no.1
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    • pp.32-37
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    • 1993
  • The equations are derived for the evaluation of the axial contact forces. The contact forces of rubber seals are analyzed as a function of the ratio of real contact length, the thickness of seal lip, the inclined angle of seal lip, and the interference between the edge of seal lip and the rotating inner ring. The experimental apparatus is developed for the test of seal lip contact force. The data for designing rubber seals are presented in terms of the ratio of real contact length, initial inclined lip angle, lip thickness. and the interference. The results obtained from the derived equation for the contact force are in good agreement with the experimental results.

Comparison on Accuracy of Static and Dynamic Contact Angle Methods for Evaluating Interfacial Properties of Composites (복합재료의 계면특성 평가를 위한 접촉각 방법의 정확도 비교)

  • Kwon, Dong-Jun;Kim, Jong-Hyun;Park, Joung-Man
    • Journal of Adhesion and Interface
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    • v.23 no.3
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    • pp.87-93
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    • 2022
  • To analyze the interfacial property between the fiber and the matrix, work of adhesion was used generally that was calculated by surface energies. In this paper, it was determined what types of contact angle measurement methods were more accurate between static and dynamic contact angle measurements. 4 types of glass fiber and epoxy resin were used each other to measure the contact angle. The contact angle was measured using two types, static and dynamic contact angle methods, and work of adhesion, Wa was calculated to compare interfacial properties. The interfacial property was evaluated using microdroplet pull-out test. Generally, the interfacial property was proportional to work of adhesion. In the case of static contact angle, however, work of adhesion was not consistent with interfacial property. It is because that dynamic contact angle measurement comparing to static contact angle could delete the error due to microdroplet size to minimize the surface area as well as the meniscus measuring error.

A Study on the Comparison of Solderability Assessment

  • Salam, B.;Ekere, N.N.;Jung, J.P.
    • Journal of the Korean institute of surface engineering
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    • v.35 no.2
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    • pp.129-137
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    • 2002
  • The purpose of solderability assessment is to predict the effectiveness of soldering process. It is important for companies pursuing zero defects manufacturing because poor solderability is the major cause of two third of soldering failures. The most versatile solderability method is wetting balance method. However, there exist so many indices for wettability in the wetting balance test e.g. time to reach 2/3 values of maximum wetting force, tine to reach zero wetting force, maximum withdrawal force. In this study, three solderability assessment methods, which were the maximum withdrawal force, the wetting balance and the dynamic contact angle (DCA), were evaluated by comparing each other. The wetting balance technique measures the solderability by recording the forces exerted from the specimen after being dipped into the molten solder. Then the force at equilibrium state can be used to calculate a contact angle, which is known as static contact angles. The DCA measures contact angles occurred during advancing and withdrawing of the specimen and the contact angles are known as dynamic contact angles. The maximum withdrawal force uses the maximum force during withdrawal movement and then a contact angle can be calculated. In this study, the maximum withdrawal force method was found to be an objective index for measuring the solderability and the experiment results indicated good agreement between the maximum withdrawal force and the wetting balance method.

Effect of Surface Free Energies on Mechanical Properties of Epoxy/Polyurethane Blend System (에폭시/폴리우레탄 블렌드 시스템의 표면 자유에너지 변화가 기계적 특성에 미치는 영향)

  • 박수진;진중성;이재락;박병기
    • Polymer(Korea)
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    • v.24 no.2
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    • pp.245-251
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    • 2000
  • A blend system prepared from epoxy(EP) and polyurethane (PU) was investigated in terms of the contact angle and mechanical properties. The contents of EP/PU were varied within 100/0~100/60 phr in the presence of 20 phr DDM (4,4'-diamino diphenyl methane) as a curing agent for epoxy resin. Contact angle measurements were performed employing a Rame-Hart contact angle goniometer. Deionized water and diiodomethane were chosen as the testing liquids. In this work, Owens-Wendt and Wu's models using a geometric mean were studied to analyze the surface free energy of blend system. For the mechanical and toughening properties of the casting specimens, the critical stress Intensity factor ($K_{IC}$) and impact test were performed. Especially, the impact test was carried out at room and cryogenic temperatures. As a result, specific or polar component of the surface free energy of the blend system was largely influenced on the addition of the PU resulting in increasing the impact strength for the excellent low- temperature performance.

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Effect of Hydrophobic Condition and Water Content on the Spectral Information of Soil Particle Surface (흙 입자 표면의 소수성 조건과 함수비가 분광정보에 미치는 영향)

  • Jeong-Jun, Park;Seung-Kyong, You;Kwang-Wu, Lee;Jung-Mann, Yun;Gigwon, Hong
    • Journal of the Korean Geosynthetics Society
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    • v.21 no.4
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    • pp.93-100
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    • 2022
  • This study describes the evaluation results on the effect of soil particle surfaces coated with various hydrophobic conditions on spectral information according to water content. Wettability test and spectral information evaluation test were performed on the hydrophobic coated standard sand. When the standard sand was coated with 1%, 3%, and 5% hydrophobic, the contact angles of sand-water interface were 130°~143°, 129°~144°, and 131°~144°, respectively. This means that the contact angle increased as the degree of hydrophobic coating increased at the same drying time, but the range of the contact angle had the same wettability. This means that the contact angle increases as the hydrophobic coating degree increases at the same drying time, whereas the contact angle range has the same wettability. As a result of spectral information evaluation, the maximum spectral reflectance of the dried sand with hydrophobic condition decreased compared to that of the hydrophilic sand, as the degree of hydrophobic increased. However, the maximum spectral reflectance was increased by increasing the degree of hydrophobic under the same water content conditions.