• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.05a
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• pp.45-52
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• 2002

The tribological role of mass transfer layer was studied with silver coatings under various ranges of load and sliding speed. Silver coating was performed with a functionally gradient coating method. Tests were performed in dry sliding conditions, using a ball-on-disk contact configuration, at the load of 0.0196-17.64 N and the sliding speed of 20-1,000 mm/s in ambient air. Optical microscope and EPMA analyses showed that contact surfaces were covered with the mass transfer layers of agglomerated wear particles depending upon the contact conditions, and they greatly influenced the tribological characteristics of the surfaces. However, the formation of mass transfer layer was suppressed as the sliding speed increased, and above a critical sliding speed, no mass transfer layer was able to form. For building up a general framework of tribological behavior of the coated silver films, all test data were summarized on a map whose axes are contact pressure and sliding speed.

• Journal of Korean Academy of Nursing Administration
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• v.2 no.2
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• pp.5-16
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• 1996

The purpose of this study is to identify the handwashing knowledge and attitudes of resistered nurses on general wards. Subjects for this study include 182 nurses working in general wards of a hospital in Seoul area. Data were collected by a questionnaire from July 30 to August 10,1996. Statistical analyses were done by the SPSS/PC program. The techniques used in this sudy included frequencies, chi-square test. The results of this study are summarized as follows. 1. 34.6% of the respondents reported that they washed their hand an average of 5 to 7 times during the work day. 2. 38.5% of the respondents reported always washing after each patient contact. Only 9.9% always washed before contact with a patient. 3. 56.6% of the respondents reported a washing time of 10 to 20 seconds, whereas 29.1% washed 21 to 30 seconds. Chi-square tests were employed to determine any differences in handwashing frequency and duration by age, working years, work position. There were no satistically significant differences among the variables. 4. 95.6% of the subjects used water and plain soap during the washing process. The respondents washed the palms of the hands, the backs of their hands and between their fingers(33%). Only 17.6% removed rings before handwashing. Similarly, 11% removed their wristwatch. The majority(96.2%) reported that they used communal textile towel to dry their hands. When asked what method they used to turn off the water faucet after washing, 98.4% reported using direct hand-to-faucet contact. 5. Nursing activities that showed the highest handwashing rates was after wound dressing(22.9%), followed by suctioning(21.4%), injection(21.2%), inserting catheter(18%). 6. Reasons cited for reduced handwashing frequency included being too busy to wash more often(74.7%), no need to wash more often(11.0%) and dry skin caused by frequent handwashing(3.3%). 7. When asked where they obtained their current knowledge of handwashing techniques, they reported professors(73.6%), resisted nurses(14.8%) and supervisor(6.6%). 8. Nursing staff thought that proper handwashing was important factor in decreasing nosocomical infections(72.4%).

• Transactions of the Korean Society of Machine Tool Engineers
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• v.16 no.6
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• pp.212-216
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• 2007

Although DLC coatings have good tribological properties, these are dependent on the deposition method, property of contact surface, and test condition. Si-DLC/DLC coatings with various Si content were deposited on Si substrates and tested using a reciprocating friction tester against steel balls. The results revealed that the tribological behavior of Si-DLC/DLC coatings was dependent on the Si content. The formation of transfer film and wear particles on the contact surface was greatly influenced by the Si content in DLC coatings. In particular, silicon oxide transfer film formed by tribochemical reaction contributed to reduce wear and friction.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.159.1-159.1
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• 2014

We report a simple method for preparing hydrophobic mesoporous silica and its use as a pre-concentrating agent of gas analytes. Hydrophobic mesoporous silica was prepared by coating PDMS (polydimethylsiloxane) thin layer on commercial mesoporous silica with thermal deposition method in a sealed chamber. By using this method, we were able to coat PDMS layer on inner-walls of pores larger than 15 nm. Also, contact angle measured on a surface consisting of PDMS-coated mesoporous silica exceeded $150^{\circ}$, implying that the surface has high water repellency. Pre-concentration ability of PDMS-coated mesoporous silica and baremesoporous silica was tested under dry and humid conditions. Adsorption and molecular desorption of gas analytes was much enhanced by PDMS-coating on mesoporous silica under both dry and humid conditions. Therefore we suggest that PDMS-coated mesoporous silica can be an efficient pre-concentration agent in order to enhance sensitivity of various detectors.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.18 no.1
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• pp.123-130
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• 2008

An analytical method for the free vibration of a flexible rectangular plate in contact with water is developed by the Rayleigh-Ritz method. The plate clamped along the edges is partially contacted with water at both sides. It is assumed that the contained water is incompressible and inviscid. The wet mode shape of the plate is assumed as a combination of the dry mode shapes of a clamped beam. The liquid motion is described by using the liquid displacement potential and determined by using the compatibility conditions along the liquid interface with the plate. Minimizing the Rayleigh quotient based on the energy conservation gives an eigenvalue problem. It is found that the theoretical results can predict excellently the fluid-coupled natural frequencies comparing with the finite element analysis result.

• Membrane Journal
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• v.11 no.1
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• pp.38-49
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• 2001

The surface of polyimide membrane was modified by plasma treatment using Ar and NH~. and the permeability and selectivity for the mixture gas $(CO_2/N_2=20/80 vol%)$ were measured. The per¬meation experiments were performed by a variable volume method at $30^{\circ}$C and total pressure of 5 atm, The effect of the plasma conditions such as treatment time, power input, gas flow rate and pressure in the reactor on the transport Dwperties of modified membranes was investigated. The surface of the plasma treated membrane was analyzed by means of FTlR - ATH, ESCA and AFM. The dependences of the wettability and the etching on plasma treatment time were investigated by use of the contact angle and the weight loss measurement. Measurements of gas pcnneability characteristic were performed using both dry and wet membranes. The effects of experimental conditions such as temperature on the membrane performance were studied.

• Journal of Korean Ophthalmic Optics Society
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• v.21 no.1
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• pp.11-21
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• 2016

Purpose: The aim of this study was to analyze the difference in tear film stability according to the wearing time when wearing clear and circle soft contact lens(circle lens) made of same material. Methods: The clear and circle contact lenses of hilafilcon B and nelfilcon A materials were respectively applied on the subjects classified as normal and dry eyes depending on their tear volume, and their tear film stability was investigated by measuring the non-invasive tear film break-up times, lens centration and the first appearing area of tear breakup after 30 mins and 6 hrs of lens wearing. Results: Non-invasive tear film breakup time significantly reduced with increase of the wearing time for normal and dry eyes when wearing clear and circle contact lenses. The starting ratio of tear film break-up was higher at the peripheral area of clear and circle lenses in all two different materials, and higher at the peripheral area of dry eyes than normal eyes. Starting ratio of tear film break-up was higher at the peripheral area of nelfilcon A lenses compared with hilafilcon B lenses, however, its change with the increase of wearing time showed a different aspect. The number of tear film break-up per unit area when wearing circle lenses of nelfilcon A increased at the central area with the wearing time while its number was higher at the peripheral area when wearing circle lenses of hilafilcon B. The centration of clear lenses made of two materials was closer to pupil compared to circle lenses with the increase of wearing time, however, a larger decentration was shown in dry eyes compared with normal eyes. Conclusions: The research revealed that an effect on tear film stability may be changed by clear lenses as well as circle lenses with coloring process according to the increase of wearing time, and the factors affecting on tear film stability may also vary depending on lens materials. Thus, the appropriate lenses should be selected by the consideration of lens material as well as coloring method/dyes according to the wearers' habit such as daily wearing time and wearing period when trying to wear clear and circle lenses.

• The Journal of the Convergence on Culture Technology
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• v.6 no.2
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• pp.183-190
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• 2020

This study was designed to investigate the current state of lens wearing and care, and to investigate eye discomfort according to the care method. Data of 209 female college students wearing lenses for more than 1 year were analyzed using the SPSS / WIN 22.0 program. 40.2% of female students wear lenses every day and 97.1% wear all day. However, only 45.4% of students washed it daily, and only 17.7 % used protein remover during wash, which resulted in poor management. 98.1% of students complained of discomfort due to the lens, and the Ocular Surface Index (OSDI) scored 42.88 ± 15.25, which was classified as a severe dry eye and threatened eye health. Therefore, it is necessary to improve students' awareness of lens management, and periodical lens inspection and management education are needed.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.12 no.1
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• pp.1-10
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• 1999

In this paper, we have investigated the effects of the environmental factors on Low Molecular Weight (LMW) silicone fluid contents existing in high temperature vulcanized (HTV) silicone rubber sample, using dipping method and contact angle, current measurement. Artificial treatments such as immersion in water, elevated temperature, UV irradiation and dry band arcing under salt-fog condition are selected as the environmental factors. This results will be helpful to investigate the degradation with time and to expect a life time, because the LMW silicone content, which is important to recovery the hydrophobicity of silicone rubber surface, show different results by each environmental factors.

• Journal of the Korean Society for Precision Engineering
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• v.27 no.4
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• pp.20-26
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• 2010

Any relative deformation between the cutting tool and the workpiece at the machining point, results directly in form and dimensional errors. The source of relative deformations between the cutting tool and the workpiece at the contact point may be due to thermal, weight, and cutting forces. This paper presents an investigation into dry and fluid machining with the objective of evaluating shape accuracy effect for the turning process of Al6061. The thermal distribution of cutting tool and cutting force was predicted using finite element method after measuring the temperature of the tool holder. To reach this goal, shape accuracy turning experiments are carried out according to cutting conditions with dry and fluid machining methods. The variable cutting conditions are cutting speed, depth of cutting and feed rate.