• Proceedings of the KSME Conference
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• 2007.05a
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• pp.409-414
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• 2007

Wettability of solid surfaces with liquids is governed by the chemical properties and the microstructure of the surfaces. We report on the preparation of liquid-repellent surfaces using surface-attached monolayers of perfluorinated polymer molecules on porous silica substrates. A covalent attachment of the polymer molecules to the substrate is achieved by generation of the polymer chains through starting a surface-initiated radical-chain polymerization of a fluorinated monomer. To this, self-assembled monolayers of azo initiators are attached to silica substrates, which are used to kick off the polymerization reaction in situ. The growth of the fluorinated polymer films and the characterization of the obtained surfaces by surface plasmon spectroscopy, XPS, and contact angle measurements is described. It is shown that perfluorinated polymer films can be grown with controlled thicknesses on flat and even on porous silica surfaces, essentially without changing the surface roughness. The combination of the low surface energy coating and the surface porosity allows generation of materials which are both water and oil repellent.

• Journal of the Korean Society for Precision Engineering
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• v.14 no.1
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• pp.119-125
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• 1997

This paper deals with an experimental investigation on an active vibration control of ahybrid smart structure(HSS) via an electro-rheological fluid actuator(ERFA) and a piezoelectric film actuator(PFA). Firstly, an HSS is constructed by inserting a silicone oil-based electro-rheological fluid into a hollow can- tilevered beam and perfectly bonding piezoelectric films ofn the upper and lower surfaces of the beam as an actuator and a sensor, respectively. The control scheme of the ERFA tuning stiffness and damping charac- teristics of the HSS with imposed electric fields is formulated as a function of excitation frequencies on the basis of field-dependent respnses. On the other hand, as for the control scheme of the PFA permitting control voltages to generate axial forces or bending moments for suppressing deflections of the HSS, a neuro sliding mode controller(NSC) is employed. Furthermore, an experimental implementation activating the ERFA and the PFA independently is established to carry out an active vibration control in both the transient and forced vibrations. The experimental results exhibit a superior ability of the gtbrid actuation system to tailor elastodynamic response characteristics of the HSS rather than a single class of actuator system alone.

• Journal of the Korean Applied Science and Technology
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• v.2 no.1
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• pp.19-23
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• 1985

In order to know the quality changes of the fat and oil foods packed in plastics film by the sunlight, we examined the sunlight transmitting rate by the kind of films and measured the acid value and peroxide value according to it. The results obtained were as follows : 1. The sunlight transmitting rate of various films was explained especial permeability under the wavelength of less than 300nm, but it marked a regular form under that of more than 30nm. 2. The vacuum evaporation film with aluminum on the polyester shuts off most of the sunlight, therefore, it has the best effect that keeps the fats and oils off rancidity. 3. The sunlight transmitting rate of the white color printing film drops about 80% as compared with not printing. 4. The preventive power against the rancidity of fats and oils is PET/Al, PET, PE, nylon and OPP film in that order. The changes of peroxide value and acid value were approximately the same as that of the sunlight transmitting rate.

• The Journal of Korean Academic Society of Nursing Education
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• v.18 no.3
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• pp.474-485
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• 2012

Purpose: The Quality and Safety Education for Nurses [QSEN] initiative group has identified six competencies (patient-centered care, teamwork and collaboration, evidence-based practice, quality improvement, safety, and informatics) for pre-licensure nursing education along with related knowledge, skills, and attitudes for each competency. The purpose of this article is to illustrate a teaching strategy that uses films to demonstrate the QSEN competencies in undergraduate nursing students. Method: A literature review was conducted to define QSEN competencies, and six feature-length commercial movies were selected through a systematic process. We provided film titles and their synopses that can be useful in teaching the QSEN six competencies to undergraduate nursing students. Results: Patch Adams for patient-centered care, Wit for teamwork and collaboration, Lorenzo's Oil for evidence-based practice, Am$\acute{e}$lie for quality improvement, Blindness and The Island for informatics can be applied in nursing classroom practices. Conclusion: Establishing the connection between QSEN competencies and cinenurducation is novel, yet it would provide a unique opportunity for nurse educators seeking to overcome the challenge of better preparing future nurses. In future studies, additional films should be considered to enhance nursing educational strategies.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.47 no.6
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• pp.5-21
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• 2015

The common production methods of nanocellulosic (cellulosic nanofibrils, CNF) materials from wood are being reviewed, together with large scale applications and particularly papermaking applications. The high energy demand for producing CNF has been one particular problem, which has been addressed over the years and can now be considered solved. Another problem was the clogging of homogenizers/microfluidizers, and the different routes to decrease the energy demand. The clogging tendency, related to the flocculation tendency of fibres is discussed in some detail. The most common methods to decrease the energy demand are TEMPO-oxidation, carboxymethylation and mechanical/enzymatic pre-treatments in the order of increased energy demand for delamination. The rheology characteristics of CNF materials, i.e. the high shear viscosity, shear thinning and the thixotropic properties are being illuminated. CNF materials are strength adjuvants that enhance the relative bonded area in paper sheets and, hence increase the sheet density and give an increased strength of the paper, particularly for chemical pulps. At the same time papers obtain a lower light scattering, higher hygroexpansion and decreased air permeability, similar to the effects of beating pulps. The negative effects on drainage by CNF materials must be alleviated through the appropriate use of microparticulate drainage aids. The use of CNF in films and coatings is interesting because CNF films and coatings can provide paper/board with good oxygen barrier properties, particularly at low relative humidities. Some other high volume applications such as concrete, oil recovery applications, automotive body applications and plastic packaging are also briefly discussed.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2012.05a
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• pp.141-142
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• 2012

Recently, surface texturing by atmospheric laser processing has been received lots of attention to improve the tribological performance of various surfaces and this laser texturing of surfaces could be considered in a large extent to improve tribological performance of PVD coated surface. Surface texturing could be performed by various manufacturing techniques such as indentation with hard materials, ion etching, abrasive jet machining, lithography, and Laser Surface Texturing (LST). Out of all these techniques, however it is generally accepted that laser surface texturing (LST) by atmospheric laser processing offers the most promising process as LST is very fast, environmentally-friendly, easy to control the shape and size of the microdimples. In this work various preliminary experimental results from the laser texturing on the PVD-coated steel substrate will be presented. Our results indicated that laser texturing definitely affect the tribological performance of the surfaces and the size as well as pattern type of laser texturing are one of the key factors. From the wear tests against an alumina counterpart ball at room temperature under oil-lubricated condition, laser surface texturing on the CrZrSiN films reduced the friction coefficients by approximately more than 5 times in the case of narrow patterned surfaces.

• Tribology and Lubricants
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• v.34 no.4
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• pp.146-159
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• 2018

This paper presents a wear analysis procedure for calculating the wear of journal bearings of a four-strokes and four-cylinder engine operating at a constant angular crank shaft speed during firing conditions. To decide whether the lubrication state of a journal bearing is in the possible region of wear scar, we utilize the concept of the centerline average surface roughness to define the most oil film thickness scarring wear (MOFTSW) on two rough surfaces. The wear volume is calculated from the wear depth and wear angle, determined by the magnitude of each film thickness on a set of oil films with thicknesses lower than the MOFTSW at every crank angle. To calculate the wear volume at one contact, the wear range ratio during one cycle is used. The total wear volume is then determined by accumulating the wear volume at every contact. The fractional film defect coefficient, asperity load sharing factor, and modified specific wear rate for the application of the mixed-elasto-hydrodynamic lubrication regime are used. The results of this study show that wear occurs only at the connecting-rod big-end bearing. Thus, simulation results of only the big-end bearing are illustrated and analyzed. It is shown that the wear volume of each wear scar group occurs consecutively as the crank angle changes, resulting in the total accumulated wear volume.

• Horticultural Science & Technology
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• v.29 no.5
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• pp.447-455
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• 2011

To investigate the effects of the improvement of postharvest quality on fresh tomato, antimicrobial microperforated (AMP) films were prepared and their antimicrobial abilities were observed. AMP films were made by coating different types of natural antimicrobial agents such as cinnamon, clove, and clary sage essential oils into microperforated (MP) films. Cinnamon essential oil of 10% (v/v) has proven to be very effective as inhibitor of the mold growth on tomato, compared to the clove and clary sage essential oils. Quality changes of fresh tomatoes packed using the natural AMP films (AMP10 and AMP30) and MP films (MP10 and MP30) during storage were evaluated. Total microbial growth, weight loss, firmness, lycopene content, and decay rate as the major quality parameters were monitored over 9 days at $15^{\circ}C$. The oxygen transmission rates and mechanical properties between the natural AMP and MP films were also compared. There was no significant difference in change of oxygen transmission rate, tensile strength and elongation between the AMP and MP films. For storage studies, the freshness of tomato packaged in AMP30 film was higher than that in OPP film (the control), MP10, MP30, and AMP10 films. Especially, AMP30 film exhibited high efficiency compared to the control for tomato decay during storage periods. Based on the results, the microperforation and antimicrobial properties of the packaged films may significantly affect the maintenance of an optimum gas composition within the package atmosphere for increasing the storage life and quality of produce. They were also effective on the inhibition of microbial growth by controlled release of antimicrobial agent at an appropriate rate from the package into the tomato. Natural antimicrobial agent coating microperforated films could use potential functional package as a method of extending the freshness of postharvest tomato for storage.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.7
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• pp.1138-1145
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• 2003

In this paper, a study on the dynamic behavior and lubrication characteristics of a reciprocating compression mechanism used in small refrigeration compressor is performed. In the problem formulation of the compressor dynamics, the viscous frictional force between piston and cylinder wall is considered in order to determine the coupled dynamic behaviors of piston and crankshaft. The solutions of the equations of motion of the reciprocating mechanism along with the time dependent Reynolds equations for the lubricating film between piston and cylinder wall and oil films of the journal bearings are obtained simultaneously. The hydrodynamic forces of journal bearings are calculated using finite bearing model and Gumbel boundary condition. And, a Newton-Raphson procedure was employed in solving the nonlinear equations of piston and crankshaft. The results explored the effects of design parameters on the stability and lubrication characteristics of the compression mechanism.

• Journal of Advanced Marine Engineering and Technology
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• v.10 no.3
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• pp.11-38
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• 1986

Past and present developments in the alignment procedures of the line shafting are discussed. It is shown that the effects of the propeller hydrodynamics and of the oil-films, built up in the journal bearings, can essentially change the static alignment. However, the inclusion of these phenomena in the alignment is not yet standard. Also the dynamic effects of natural frequencies and vibratory excitations are not yet accounted for in the general case, although also these aspects can influence the safe operation of the line shafting. Therefore a plea is made to develop a more complete and thus a more rational alignment procedure.