학교 수업 현장에서 활용할 수 있는 표면장력 측정 장치 개발

박철규,홍훈기 한국현장과학교육학회 2018 현장과학교육 Vol.12 No.2

In the curriculum of chemistry in Korea, surface tension is a concept that has been consistently presented with intermolecular interaction. However, the surface tension till now tended to be presented only as a phenomenon or a case rather than a scientific definition. Therefore, in this study, we tried to develop a surface tension measurement instrument based on the scientific definition in order to provide a new teaching and learning method for surface tension. We analyzed limitations of surface tension measurement instruments proposed in the previous research, and developed a surface tension measurement instrument based on Wilhelmy plate method focusing on intuitiveness, convenience and accuracy. From several measurements of surface tension for six different liquids, it was confirmed that the developed instrument can accurately and precisely measure the surface tension in a short time. The proposed instrument can be used for surface tension teaching and measurement in the future class at school. 우리나라 화학 교육과정에서 표면장력은 분자 간 상호작용과 함께 지속적으로 제시되어 온 개념이지만, 지금까지 다뤄진 표면장력은 과학적 정의보다는 단순히 현상이나 사례의 측면으로만 제시되는 경향이 있다. 따라서 본 연구에서는 표면장력에 대한 새로운 교수학습 방법을 마련하고자 과학적 정의에 기반을 둔 표면장력 측정 실험 장치를 개발하고자 하였다. 선행 연구에서 제시한 표면장력 측정 장치들의 한계점을 분석하였고, 실험의 직관성, 편리성, 정확성 등에 초점을 맞추어 Wilhelmy 평판법(Wilhelmy plate method) 기반의 표면장력 측정 장치를 개발하였다. 6종 액체의 표면장력을 측정함으로써 제작된 표면장력 측정 장치가 짧은 시간 내에 정확하고 정밀한 값을 측정할 수 있다는 것을 확인하였다. 본 연구에서 제안하는 표면장력 측정 장치는 추후 화학 수업 현장에서 표면장력 교수와 측정을 위해 사용될 수 있다.

콘택트렌즈 관리용액의 미셀임계농도 및 표면장력과 세척력 간의 상관관계

변현영,성형경,문준식,이아영,권세영,김소라,박미정 한국안광학회 2014 한국안광학회지 Vol.19 No.1

The present study was aimed to figure out the correlation amongst the evaluation methods for criticalmicelle concentration, surface tension and protein cleaning efficacy to evaluate cleaning efficacy of contact lenscare products. Methods: The critical micelle concentration of surfactants and the actual concentration ofsurfactants in contact lens care solutions were investigated by employing references published and relatedinformation. Surface tension of contact lens care solutions was measured by surface tension device at 25±1oC,and contact lenses made of lotrafilcon A, comfilcon A and balafilcon A were washed with contact lens caresolutions after the incubation in artificial tears for 14 days and their cleaning efficacy was compared. Results:Among the 22 contact lens care products, 9 products provided the label of the concentration of surfactant, and 7products showed higher concentration of surfactant than the critical micelle concentration reported in references. As a result of measuring surface tension, the surface tension of lens care products for soft contact lens wasgenerally lower than other care products. When examined the removal effect of protein deposited on lens surface,it was known that the care products having lower surface tension showed higher protein removal efficiency. Conclusions: The surface tension is low when surfactant concentration in contact lens care solutions is high, andthe removal effect of protein deposited is accordingly increased with the decrease of surface tension. Thus, theseindicate the correlation amongst the evaluation methods for cleaning efficacy. 본 연구에서는 콘택트렌즈 관리용품의 세척력 평가를 위해 미셀임계농도 평가법, 표면장력 평가법 및 단백질세척효율평가법의 상관관계에 대해 알아보고자 하였다. 방법: 계면활성제의 미셀임계농도와 실제 콘택트렌즈 관리용액의 계면활성제 농도를 문헌과 관련 자료들을 이용하여 조사하였다. 표면장력기기로 25±1oC에서 콘택트렌즈 관리용액의 표면장력을 측정하였으며, lotrafilcon A, comfilcon A, balafilcon A재질의 렌즈를 인공누액에 14일 동안 침착시킨 후 콘택트렌즈 관리용액으로 세척하여 세척효율을 비교하였다. 결과: 콘택트렌즈 관리용품 22제품 중 계면활성제 농도가 표시된 제품은 9제품이었으며 문헌상의 미셀임계농도보다 계면활성제 농도가 더 높은 제품은 7제품이었다. 표면장력을 측정한 결과 대체적으로 소프트렌즈용 관리용품의 표면장력이 다른 관리용품보다 낮음을 알 수 있었으며, 렌즈에 침착된 단백질 제거효과 분석 결과에서는 표면장력이 더 낮은 제품의 단백질 제거효율이 더 높은 것을 알 수 있었다. 결론: 콘택트렌즈 관리용액의 계면활성제 농도가 높은 경우 표면장력이 낮으며, 표면장력이 낮을수록 침착된 단백질 세척 효율이 높아져 세척력 평가법 간에 서로 상관관계가 있음을 밝혔다.

Surface tension-affected laminar film condensation problems

Hua Sheng Wang,John W. Rose 대한기계학회 2007 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.21 No.11

Following Nusselt [1] there were few developments in the theory of laminar film condensation until the advent of digital computers in the 1950s. Approximations used by Nusselt, namely neglect of inertia, convection and surface shear stress (for the free convection case) were then found to give very accurate results for the normal practical range of vapour-to-surface temperature difference. Subsequent developments treated the gas phase and dealt with superheated vapour, condensation in the presence of a non-condensing gas and condensation of mixtures. The temperature discontinuity at the vapour-liquid interface has been studied experimentally and theoretically since the 19<SUP>th</SUP> century and more recently in the 1960s by experiments using liquid metals. In the present paper the focus is on the condensate film and, in particular, the role played by surface tension which is important for condensation on finned surfaces and in microchannels, owing to abrupt changes in curvature of the condensing surface. The way in which surface tension affects condensation heat transfer and difficulties which arise are first illustrated by reference to condensation on a smooth horizontal tube, where the effect of surface tension on heat transfer is minimal. Practically more relevant cases of condensation in microchannels and on finned surfaces and are then discussed and recent results presented.

Study on droplet formation with surface tension for electrohydrodynamic

Soo-Hong Lee,Xuan Hung Nguyen,고한서 대한기계학회 2012 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.26 No.5

"Droplet ejection from an electrohydrodynamic (EHD) inkjet nozzle depends on many factors such as an onset voltage, liquid conductivity,surface tension, etc. Since the surface tension has an influence on the contact angle between the nozzle surface and the liquid droplet,the surface tension change should be investigated for the control of the droplet ejection. In this study, surfactant, which can weaken the surface tension force, was used to analyze the effect of the surface tension. Furthermore, hydrophobic coating of the nozzle surface was considered as another factor for the droplet ejection. Also, a flow visualization technique was developed to observe the droplet formation and ejection from the EHD inkjet nozzle by various surface tension values."

다양한 산소분압에 따른 용융 Ag-Sn 및 Ag-Cu 합금의 표면장력

민순기,이준호,Min, Soon-Ki,Lee, Joon-Ho 한국재료학회 2009 한국재료학회지 Vol.19 No.1

A semi-empirical method to estimate the surface tension of molten alloys at different oxygen partial pressures is suggested in this study. The surface tension of molten Ag-Sn and Ag-Cu alloys were calculated using the Butler equation with the surface tension value of pure substance at a given oxygen partial pressure. The oxygen partial pressure ranges were $2.86{\times}10^{-12}$-$1.24{\times}10^{-9}$ Pa for the Ag-Sn system and $2.27{\times}10^{-11}$-$5.68{\times}10^{-4}$ Pa for the Ag-Cu system. In this calculation, the interactions of the adsorbed oxygen with other metallic constituents were ignored. The calculated results of the Ag-Sn alloys were in reasonable accordance with the experimental data within a difference of 8%. For the Ag-Cu alloy system at a higher oxygen partial pressure, the surface tension initially decreased but showed a minimum at $X_{Ag}$ = 0.05 to increase as the silver content increased. This behavior appears to be related to the oxygen adsorption and the corresponding surface segregation of the constituent with a lower surface tension. Nevertheless, the calculated results of the Ag-Cu alloys with the present model were in good agreement with the experimental data within a difference of 10%.

변형를 속도에 따른 인장/압축 경화 거동의 근사를 위한 수정 Two-surface 모델

배기현(G. H. Bae),허훈(H. Huh) 한국소성가공학회 2011 한국소성가공학회 학술대회 논문집 Vol.2011 No.5

This paper suggests a modified two-surface model to describe the tension/compression hardening curves of auto-body steel sheets with the variation of the strain rate. Tension/compression tests of auto-body steel sheets were carried out by utilizing the simple clamping device developed by Bae et al. [~] in order to obtain tension/compression hardening curves. To consider the strain rate effect on the hardening behavior, a gap function used for the two-surface model was modified by inserting the strain rate hardening term. The approximation results show that the modified two-surface model can accurately describe the tension/compression hardening behavior with the variation of the strain rate.

Surface Active Salivary Metabolites Indicate Oxidative Stress and Inflammation in Obstructive Sleep Apnea

Kim Jiyoung,An Sangmin,Kim Yisook,Yoon Dae-Wui,Son Soo Ah,Park Jong-Wan,Jhe Wonho,Park Chan-Soon,Shin Hyun-Woo 대한천식알레르기학회 2023 Allergy, Asthma & Immunology Research Vol.15 No.3

Purpose: Obstructive sleep apnea (OSA), a highly prevalent and potentially serious sleep disorder, requires effective screening tools. Saliva is a useful biological fluid with various metabolites that might also influence upper airway patency by affecting surface tension in the upper airway. However, little is known about the composition and role of salivary metabolites in OSA. Therefore, we investigated the metabolomics signature in saliva from the OSA patients and evaluated the associations between identified metabolites and salivary surface tension. Methods: We studied 68 subjects who visited sleep clinic due to the symptoms of OSA. All underwent full-night in-lab polysomnography. Patients with apnea-hypopnea index (AHI) < 10 were classified to the control, and those with AHI ≥ 10 were the OSA groups. Saliva samples were collected before and after sleep. The centrifuged saliva samples were analyzed by liquid chromatography with high-resolution mass spectrometry (ultra-performance liquid chromatography-tandem mass spectrometry; UPLC-MS/MS). Differentially expressed salivary metabolites were identified using open source software (XCMS) and Compound Discoverer 2.1. Metabolite set enrichment analysis (MSEA) was performed using MetaboAnalyst 5.0. The surface tension of the saliva samples was determined by the pendant drop method. Results: Three human-derived metabolites (1-palmitoyl-2-[5-hydroxyl-8-oxo-6-octenoyl]-sn-glycerol-3-phosphatidylcholine [PHOOA-PC], 1-palmitoyl-2-[5-keto-8-oxo-6-octenoyl]-sn-glycerol-3-phosphatidylcholine [KPOO-PC], and 9-nitrooleate) were significantly upregulated in the after-sleep salivary samples from the OSA patients compared to the control group samples. Among the candidate metabolites, only PHOOA-PC was correlated with the AHI. In OSA samples, salivary surface tension decreased after sleep. The differences in surface tension were negatively correlated with PHOOA-PC and 9-nitrooleate concentrations. Furthermore, MSEA revealed that arachidonic acid-related metabolism pathways were upregulated in the after-sleep samples from the OSA group. Conclusions: This study revealed that salivary PHOOA-PC was correlated positively with the AHI and negatively with salivary surface tension in the OSA group. Salivary metabolomic analysis may improve our understanding of upper airway dynamics and provide new insights into novel biomarkers and therapeutic targets in OSA.

자유표면에 작용하는 와 유동의 상호작용에 관한 연구

손권,김경훈,김석우 慶熙大學校 레이저 工學硏究所 2002 레이저공학 Vol.13 No.-

Today, the research to examine a fact that interaction between the air and the fluid free surface affects the steady state flow and the air has been made. We researched the interaction between vortex pairs which created by the end of delta wings and free surface on each condition. Another purpose of this study is to investigate the effect of surface active material which can change the surface tension. And we must consider when we refer to turbulent flow on surface tension. Therefore, this research examined the growing process of vortex pairs on condition of clean, contaminated free surface and wall after we made vortex pairs through counter rotating flaps. The results of this study suggest that vortex pairs in clean free surface rise safely. But the vortex pairs in contaminated free surface and rigid wall, no slip is made secondary vortex or rebounding. However the secondary vortex in rigid wall, no slip is stronger than before, and we can find the shape of vortex which roll up more completely. However, these are disappeared by the effect of wall.

Synthesis and characteristic of double-tail cationic surfactants by using myristoyl chloride

박종권,정노희 한국공업화학회 2015 한국공업화학회 연구논문 초록집 Vol.2015 No.0

The use of cationic surfactants is limited in various applications because of little irritation, although cationic surfactants have excellent properties such as low surface and interfacial tensions. Double tail type of cationic surfactant was synthesized and confirmed by FT-IR and 1H-NMR spectroscopy. Surface tensions were measured by surface tensiometer (Sigma 70). Surface tensions and interfacial tensions of the synthesized surfactants were below 30 mN/m and below 35mN/m, respectively. Their c.m.c. values were evaluated by surface tension method. The emulsifying properties of synthesized cationic surfactants and sodium dodecyl sulfate (SDS), tetradecyl trimethyl ammonium bromide (TTAB) was investigated.

Model of the onset of liquid entrainment in large branch T-junction with the consideration of surface tension

Liu, Ping,Shen, Geyu,Li, Xiaoyu,Gao, Jinchen,Meng, Zhaoming Korean Nuclear Society 2021 Nuclear Engineering and Technology Vol.53 No.3

The T-junction exists widely in industrial engineering, especially in nuclear power plants, which plays an important part in nuclear power reactor thermal-hydraulics. However, the existing prediction models of the liquid entrainment are mainly based on the small branches or small breaks while there are a few researches for large branches (d/D > 0.2). Referring to the classical models about the onset of liquid entrainment of the T-junction, most of previous models regard liquid as ideal working fluid and ignore surface tension. This paper aims to study the effect of surface tension on the liquid entrainment, and develops an improved model based on the reasonable assumption. The establishment of new model employs the methods of force analysis, dimensional analysis. Besides, the dimensionless Weber number is adopted innovatively into the model to show the effect of surface tension. What is more, in order to validate the new model, three kinds of working fluids with different surface tensions are creatively adopted in the experiments: water, silicone oil and ethyl alcohol. The final results show that surface tension has a nonnegligible effect on the onset of liquid entrainment in large branch T-junction. The new model is well matched with the experimental data.