• Title/Summary/Keyword: 표면 젖음도

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Wettability Characteristics of the Laser Grooved Surfaces (Laser Groove 표면의 젖음 특성에 관한 연구)

  • Jang, Mu Yeon;Kim, Tae Wan
    • Tribology and Lubricants
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    • v.35 no.5
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    • pp.294-299
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    • 2019
  • Most previous studies on water repellent surfaces using lasers rely on the use of pico- or femtosecond lasers. However, in industrial application, these methods have the disadvantages of high cost and low efficiency. In this study, we implement a hydrophobic surface using a high-power general-purpose diode laser. We have fabricated the microsurface using laser groove processing technology, and we present the correlation of wettability characteristics with space and width. The metal material is stainless steel (SUS 304), and the groove height during laser processing is set to $30{\mu}m$ to evaluate the wettability based on the gap and width of various grooves. Results show that the contact angle of the groove-shaped surface is increased by $40^{\circ}$ or more as compared with the surface without patterning, and the contact angle in the parallel direction is greater than that in the perpendicular direction. Results from contact angle hysteresis measurement experiments show that the groove width has a greater influence on the contact angle history than does the gap between grooves. In addition, the coating reveals that the contact angle can be increased using a chemical method and that the laser grooving process can further improve the wetting properties of the surface.

Relative Corrosion Environment Conditions of Steel Box Members Examined by Corrosion Current Measurement (부식전류 평가를 통한 강박스 부재의 상대적 부식환경 평가)

  • Jin, Yong-Hee;Ha, Min-Gyun;Jeong, Young-Soo;Ahn, Jin-Hee
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.24 no.6
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    • pp.171-179
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    • 2020
  • In this study, a local corrosion environment monitoring was conducted using steel box specimen fabricated to be the same as actual steel bridge members. The steel box specimen that obtained the same corrosion environment as a steel bridge was classified into the upper plate, bottom plate and web plate. Atmospheric corrosion monitoring sensors(ACM sensors) were installed in each corrosion monitoring member of a steel box specimen to measure the corrosion current and examine time of wetness for each monitoring member. The time of wetness and accumulated corrosion current of each monitoring member were calculated from the measured corrosion current using ACM sensors. The corrosion environment that appeared for each of the steel box members was evaluated from monitoring corrosion environment data as the corrosion current, time of wetness, mean corrosion depth of each monitoring member. Additionally, the atmospheric corrosion environment monitoring was also conducted to compare with the local corrosion environment of steel box members. From these local corrosion environment monitoring for the steel box specimen, the relationship between the relative corrosion environment and mean corrosion depth of each steel box member was examined.

A Study on Surface Properties of Mechanical Interfacial Behavior of DGEBA/PMR-15 Blends (DGEBA/PMR-15 블렌드계의 표면특성 변화가 기계적 계면특성에 미지는 영향)

  • Park, Soo-Jin;Lee, Hwa-Young;Han, Mijeong;Hong, Sung-Kwon
    • Journal of Adhesion and Interface
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    • v.4 no.1
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    • pp.1-8
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    • 2003
  • In this work, the effect of PMR-15 content on the variation of surface free energy of the DGEBA/PMR-15 blend system was investigated in terms of contact angles and mechanical interfacial tests. Based on FT-IR result of the blend system. C=O (1,772, $1,778cm^{-1}$) and C-N ($1,372cm^{-1}$) peaks appeared with imidization of PMR-15 and -OH ($3,500cm^{-1}$) peak showed broadly at 10 phr of PMR-15 by ring-opening of epoxy. Contact angle measurements were performed by using deionized water and diiodomethane as testing liquids. As a result, the surface free energy of the blends gave a maximum value at 10 phr of PMR-15, due to the significant increasing of specific component. The mechanical interfacial properties measured from the critical stress intensity factor ($K_{IC}$) and the critical strain energy release rate ($G_{IC}$) showed a similar behavior with the results of surface energetics. This behavior was probably attributed to The improving of the interfacial adhesion between intermolecules, resulting from increasing the hydrogen bondings of the blends.

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Comparison of removal torque of dual-acid etched and single-acid etched implants in rabbit tibias (단일, 이중 산처리 임플란트의 회전제거력 비교)

  • Kim, Jong-Jin;Cho, Sung-Am
    • The Journal of Korean Academy of Prosthodontics
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    • v.57 no.4
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    • pp.335-341
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    • 2019
  • Purpose: Chemically strong-acids (HF and $HCl/H_2SO_4$) dual etching implant surfaces have higher strengths of osseointegration than machined implant surfaces. However, the dual acid treatment deteriorates the physical properties of the titanium by weakening the fatigue resistance of the implant and causing microcracks. The removal torque comparison between the dual-acid etched (hydrochloric acid, sulfuric acid, HS) and single-acid etched implants (hydrochloric acid, H) could reveal the efficiency of implant surface acid treatment. Materials and methods: Nine $3.75{\times}4mm$ dual-acid etched SLA implants and nine single-acid etched SLA implants were inserted into New Zealand rabbit tibias. After 10 days, removal torque, roughness, and wetting angle were measured. Results: Mean removal torque values were as follows: Mean removal torque were 9.94 Ncm for HS group and 9.96 Ncm for H group (P=.995). Mean surface roughness value were $0.93{\mu}m$ for HS group and $0.84{\mu}m$ for H group (P=.170). Root mean square roughness (RSq) values were $1.21{\mu}m$ for HS group and $1.08{\mu}m$ for H group (P=.294), and mean wetting angle values were $99^{\circ}$ for HS group and $98^{\circ}$ for H group (P=.829). Statistical analysis showed no significant difference between the removal torques, roughness, or wetting angles of the two groups. Conclusion: In this experiment, we found no significant difference in removal torque, roughness, or wetting angle between dual-acid etched and single-acid etched implants.

A Development of The Road Surface Decision Algorithm Using SVM(Support Vector Machine) Clustering Methods (SVM(Support Vector Machine) 기법을 활용한 노면상태 판별 알고리즘 개발)

  • Kim, Jong Hoon;Won, Jae Moo
    • The Journal of The Korea Institute of Intelligent Transport Systems
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    • v.12 no.5
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    • pp.1-12
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    • 2013
  • Road's accidents caused by Ice, snow, Wet of roads surface conditions and weather conditions situations that are constantly occurring. That is, driver's negligence and safe driving ability of individuals due to lack of awareness, and Road management main agent(the government and the public, etc.) due to road conditions, if there is insufficient information. So Related research needs is a trend that is required. In this study, gather Camera(Stereo camera)'s image data, and analysis polarization coefficients and wavelet transform. And unlike traditional single-dimensional classification algorithms as multi-dimensional analysis by using SVM classification techniques, develop an algorithm to determine road conditions. Four on the road conditions (dry, wet, snow, ice) recognition success rate for the detection and analysis of experiments.

Microcontact Printing of Bacteria Using Hybrid Agarose Gel Stamp (혼성 아가로즈젤 스탬프를 이용한 박테리아 마이크로 컨택트 프린팅)

  • Shim, Hyun-Woo;Lee, Ji-Hye;Lee, Chang-Soo
    • KSBB Journal
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    • v.21 no.4
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    • pp.273-278
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    • 2006
  • The noble method of hybrid agarose gel microstamp fabricated by replica molding against PDMS master to make bacteria patterns on agar surface was presented. After the fabricated hybrid agarose gel microstamp was inked with E. coli, we could obtain 2 dimensional bacterial arrays with $50{\mu}m$ circular spots. And the various shaped patterns based on experimental design were easily generated. The analysis of mean fluorescent signal was showed that bacterial pattern have high contrast between spots and background and homogeneity of pattern. Our proposed method solved the problem of wetting and handling with small soft agarose gel microstamp when bacteria were used for ink. The agarose gel stamp provides appropriate environment to inked bacteria, which is essential technology for cell patterning with high retaining viability during the patterning process. This method is reproducible, convenient, rapid, and could be applied to screening system, study of cell-surface interaction, and microbial ecology.

Evaluation of Wettability and Interfacial Property of Glass Fiber Reinforced Composite with Different Glass Fiber Conditions via Capillary Effect (Capillary 특성을 활용한 섬유 조건에 따른 유리섬유강화 복합재료의 함침성 및 계면강도 평가)

  • Kim, Jong-Hyun;Kwon, Dong-Jun;Park, Joung-Man
    • Composites Research
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    • v.34 no.5
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    • pp.305-310
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    • 2021
  • Mechanical properties of fiber reinforced composites were affected to fiber volume fractions (FVF) and interfacial property by sizing agent conditions. An optimum interface can relieve stress concentration by transferring the mechanical stress from the matrix resin to the reinforcements effectively, and thus can result in the performance of the composites. The interfacial properties and wettability between the epoxy resin and glass fiber (GF) were evaluated for different sizing agent conditions and FVFs. The surface energies of epoxy resin and different sizing agent treated GFs were calculated using dynamic and static contact angle measurements. The work of adhesion, Wa was calculated by using surface energies of epoxy matrix and GFs. The wettability was evaluated via the GF tow capillary test. The interfacial shear strength (IFSS) was evaluated by microdroplet pull-out test. Finally, the optimized GFRP manufacturing conditions could be obtained by using wettability and interfacial property.

Interfacial Evaluation of Single-Carbon Fiber/Phenolic and Carbon Nanotube-Phenolic Composites Using Micromechanical Tests and Electrical Resistance Measurements (미세역학시험법과 전기저항 측정을 이용한 탄소섬유/페놀수지 및 탄소나노튜브-페놀수지 복합재료의 계면특성 평가)

  • Wang, Zuo-Jia;Kwon, Dong-Jun;Gu, Ga-Young;Park, Jong-Kyoo;Lee, Woo-Il;Park, Joung-Man
    • Journal of Adhesion and Interface
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    • v.11 no.4
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    • pp.149-154
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    • 2010
  • Interfacial evaluation was investigated for single-carbon fiber/phenolic and carbon nanotube (CNT)-phenolic composites by micromechanical technique and electrical resistance measurement combined with wettability test. Compressive strength of pure phenol and CNT-phenolic composites were compared using Broutman specimen. The contact resistance of CNT-phenolic composites was obtained using a gradient specimen by two and four-point methods. Surface energies and wettability by dynamic contact angle measurement were measured using Wilhelmy plate technique. Since hydrophobic domains are formed as heterogeneous microstructure of CNT in the surface, the dynamic contact angle exhibited more than $90^{\circ}$. CNT-phenolic composites exhibited a higher apparent modulus than neat phenolic case due to better stress transferring effect. Work of adhesion, $W_a$ between single-carbon fiber and CNT-phenolic composites exhibited higher than neat phenolic resin due to the enhanced viscosity by CNT addition. It was consistent with micro-failure patterns in microdroplet test.

Analysis of Capillary Flow in Open-Top Rectangular Microchannel (상판이 없는 직사각형 단면의 미세채널에서 모세관 유동 분석)

  • Park, Eun-Jung;Cho, Ji-Yong;Kim, Jeong-Chul;Hur, Dae-Sung;Chung, Chan-Il;Kim, Jung-Kyung
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.34 no.1
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    • pp.77-82
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    • 2010
  • Our study aims to understand the flow of liquid in an open-top rectangular microchannel that can be used in micro total analysis systems ($\mu$-TAS) because it has advantages in terms of light transmission and energy efficiency. We measured the liquid velocity using particle tracking technique and conducted a simulation with computational fluid dynamics by altering the area of channel cross section and channel length for the capillary-driven flow in the open-top rectangular microchannel. When liquid water drops to an entrance of the fabricated microchannel with a height of 20 μm and a width of 20 ${\mu}m$, it flows along the microchannel by only capillary force. In the wetting behavior of the liquid, important parameters of this flow are channel size, contact angle and liquid properties such as surface tension and viscosity, which are used to control the flow of liquid in the microchannel.

Adhesion Properties of UV-curable Acrylic PSA Tape for Automotive Sidemolding and Emblem (자동차용 사이드 몰딩과 엠블럼 적용을 위한 UV 경화형 아크릴 점착 테이프의 점착물성)

  • Park, Ji-Won;Lee, Seung-Woo;Kim, Hyun-Joong;Won, Dong-Bok;Kim, Dong-Bok;Lee, Kang-Shin;Woo, Hang-Soo;Kim, Eun-Ah
    • Journal of Adhesion and Interface
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    • v.12 no.3
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    • pp.81-87
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    • 2011
  • In this study, UV curing and crosslinking process was introduced for synthesis of acrylic foam tape that can be applied to the the automotive assembly process. Polymerized adhesive are laminated to baseform and varying the thickness of specimens were prepared. To measure basic mechanical properties, stainless steel was used. And in the test peel, dynamic shear and t-block were used. The acrylform adhesive show better results compare with typical adhesive and the properties depand on external factors - thick, wetting time -. To analysis functions of acrylic foam adhesive used to automobile production, evaluate the adhesive properties on the various plastic substrate. In PP and PE are categorized low surface energy materials, their properties have not been expressed. But dynamic shear tests show that some properties could be expressed by the difference break mechanism.