• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.3
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• pp.753-764
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• 1996

The metal matrix composites(MMC) are currently receiving a great deal of attention. These composites possess exellent mechanical and physical properties such as modulus, strength, wear resistance and thermal stability, which make them very attractive for use in automotive piston. In this study, $Al/{Al_2}{O_3}$(15%) composites are fabricated by the squeeze casting method. Mechanical properties such as tensile strength and ductility are performed at room and elevated temperature($250^{\circ}C$ and $350^{\circ}C$), respectively. Through thermomechanical analyser, thermal expansion coefficient of $Al/{Al_2}{O_3}$ composites are conducted for ranging from room temperature to ($400^{\circ}C$.And bending fatigue tests are also performed by the rotary bending machine at room temperature.The tensile strength and elastic modulus have been improved up to 38% and 35% by the addition of the reinforcements, respectively. Thermal expansion coefficients of MMCs which is located normal and parralel to the applied pressure are showed slightly different less than 10%. Fatigue strengh of the composite was improved by about 20% compared with that of unreinforced Al alloy. The results of this study will be used to understand the basic fracture behavior of MMCs and eventually to expand the applocation of MMCs as a machine parts undertaken various loadings.

• The Journal of Korean Academy of Prosthodontics
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• v.56 no.4
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• pp.347-353
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• 2018

Gradual attrition is a normal process of aging, but severe attrition causes occlusal disharmony, functional disorder and esthetic problems. The collapse of posterior support may cause attrition of anterior teeth, and loss of occlusal vertical dimension (OVD). And it induces the pathologic change of the TMJ, unaesthetic facial appearance and decreased masticatory function. In this case, 70 year-old male presented with decreased vertical dimension and esthetic problems due to worn dentition. Based on assessment of intraoral findings, diagnostic cast and radiographic examination, full-mouth rehabilitation with increase of OVD was planned. After 10 month follow-up, occlusal stability is maintained and through this procedure, satisfactory outcomes were achieved in esthetic and functional aspects.

• Tribology and Lubricants
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• v.27 no.4
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• pp.193-197
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• 2011

Friction behavior of nanoporous anodic aluminum oxide(AAO) film was investigated. A 60 ${\mu}m$ thick AAO film having nanopores of 45 nm diameter with 105 nm interpore-diatance was fabricated by mild anodization process. The AAO film was then saturated with paraffinic oil. Reciprocating ball-on-flat sliding friction tests using 1 mm diameter steel ball as the counterpart were carried out with normal load ranging from 0.1 N to 1 N in an ambient environment. The morphology of worn surfaces were analyzed using scanning electron microscopy. The friction coefficient significantly increased with the increase of load. The boundary lubrication layer of paraffinic oil contributed to the lower friction at relatively low load (0.1 N), but it is less effective at high load (1 N). Plastic deformed layer patches were formed on the worn surface of oil-enriched AAO at relatively low load (0.1 N) without evidence of tribochemical reaction. On the other hand, thick tribolayers were formed on the worn surface of both oil-enriched and as-prepared AAO at relatively high load (1 N) due to tribochemical reaction and material transfer.

• Biomedical Science Letters
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• v.8 no.3
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• pp.195-202
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• 2002

Osteoarthritis (OA), the most common form of arthritis, involves the destabilization of the normal balance between the degradation and the synthesis of articular cartilage and subchondral bone within a joint. As articular cartilage degrades over time, its smooth surface roughens and bone-against-bone contact ensues, producing the inflammation response symptomatic of this 'wear and tear' disease. Although a variety of genetic, developmental, metabolic, and traumatic factors may initiate the development of osteoarthritis, its symptoms (joint pain, stiffness, and curtailed function) typically evolve slowly, and patients experience periods of relative calm alternation with episodes of inflammation and pain. Rheumatoid arthritis (RA), an autoimmune disease of unknown etiology characterized by chronic synovitis and cartilage destruction, affect 1% of the total population. Cartilage is a specialized connective tissue in which the chondrocytes occupy only 5% of the volume. Cartilage is particularly rich in extracellular matrix, with matrix making up 90% of the dry weight of the tissue chondrocytes have cell processes that extend a short distance into the matrix, but do not touch other cells thus in cartilage, cell-matrix interactions are essential for the maintenance of the extracellular matrix. In this study, subtractive hybridization method was utilized to detect genes differentially expressed in chondrocytes treated with methylprednisolone. We have isolated 57 genes that expressed differentially in the chondreocytes by methylprednisolone. 13 clones of them were analyzed with sequencing and their homologies were searched. 8 cDNAS included KIAA 0368, upregulated during skeletal muscle growth 5 (usmg 5), ribosomal protein S 18 (RPS 18), skeletal muscle ryanodine receptor, radial spoke protein 3 (RSP 3), ribosomal protein QM, ribosomal protein L37a (RPL37A), cytochrome coxidase subunit VIII (COX8).

• The Journal of the Acoustical Society of Korea
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• v.8 no.1
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• pp.5-12
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• 1989

This paper is concerned with the characteristics on the statistical parameters of vibration signal from bearing with changing its operating conditions as well as the spreading of faults. The rms, Kurtosis, crest factor, probability of exceedance and probability density function have been chose as the statistical parameters. To characterize of each, vibration signals have been recorded from four ball tester at different loads, operation speeds and time. The values of the statistical parameters for each frequency band have been calculated after A/D conversion and digital filtering of the recorded signals. It has been found that unlike rms values the statistical parameters such as Kurtosis etc. are almost unchanging with the change of the operating conditions such as load and speed. This suggests that the statistical parameters may be used for determining the development of faults independent of the operating conditions. In fact, the statistical parameters deviate considerably from their respective normal values when the faults developed under load conditions in the samples, conforming the suggestion.

• Journal of the Korea Fashion and Costume Design Association
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• v.22 no.2
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• pp.137-149
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• 2020

The purpose of this study is to identify the perception of New-Hanbok Skirts that female consumers have and to analyze the design preference based on the analysis of designs of skirt products currently in distribution. Based on the analysis of the New-Hanbok brand website, the research was conducted through a survey of 355 women in their 20s and older. The survey consisted of 24 questions which were divided into pattern, color, material, and recognition type questions. The research results are as follows. First, most adult women answered that a New-Hanbok skirt is appropriate to wear at a holiday, anniversary, or outer dress for the spring and autumn seasons, and the design is the most important thing when considering buying. However, the ratios of wearing experience and possession were very low. Second, the preferred design aspects of a New-Hanbok skirt were the Jarak-skirt or Deot-skirt, calf-length, 5cm width of the waistband, 3cm uniform crease, a normal length waistband, bright neutral colors, and a waistband in different colors. For the double skirt, the design that shows 4cm of lining fabric and the different colors of upper fabric was the most preferred. The most preferred material was plain cotton. On the other hand, small floral patterns were preferred for patterned materials, and opaque upper fabric was most preferred for the double skirt. Through this study, it was confirmed that the Hanbok is seen as a positive aspect for modern consumers.

• Journal of East-West Nursing Research
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• v.24 no.1
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• pp.28-35
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• 2018

Purpose: The purpose of this study was to investigate the image of nurses portrayed in the internet photographs. Methods: A total of 184 photographs were extracted through the Google portal site using a search term, 'nurse'. Based on the findings of previous studies, a content analysis was conducted with three categories: appearance characteristics, photographic scene, and photographic source. Results: The result revealed that in the photos of appearance characteristics, 237 (98.3%) out of 241 nurses had a normal or less frame, 235 (97.5%) were well-groomed, and 103 (42.7%) wore pants. In addition, 51 (21.2%) wore a cap (21.2%) and 12.0% were male. In the photographic scene, 69 (37.5%) portrayed nursing activities and 36 (19.6%) suggestiveness. In the suggestive photos, all of nurses were female (${\chi}^2=7.63$, p=.021) and they were more likely to have small frames (${\chi}^2=48.40$, p<.001) and wear caps (${\chi}^2=113.54$, p<.001) and skirts (${\chi}^2=39.96$, p<.001). Conclusion: This study showed that the photographs of the nurses wearing a cap and expressing the nurse as a sexual object still appeared. There is a need for a systematic image enhancement strategy so that actual images of nurses can be projected on the internet photographs.

• Fashion & Textile Research Journal
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• v.17 no.6
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• pp.1013-1019
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• 2015

As the interest in leisure and health increases, the domestic outdoor wear industry becomes bigger. The waterproofness of fabrics does not ensure the waterproofness of garments because of the stitch holes during the sewing process even with the seam sealing tapes. Thus the water leakage often becomes a problem during the end use. Still companies use fabrics waterproofness data for garments marketing because they are simple to run the test, less expensive than the whole garment testing, and easy to achieve the quality control. In this study the rain tower system for evaluating the waterproofness of garments has been developed and the waterproofness of the selected waterproof and breathable garments in the market were tested. The rain tower was consisted of rain tower room, rainfall forming system and measurement system. Two different levels of rainfall can be simulated with this system(100l/m²/hr and 450l/m²/hr). Jackets in the market have been tested at two different rainfall conditions. The temperature and humidity data inside jackets didn't provide much information on the waterproofness at severe rainfall condition(450l/m²/hr, 1 hour). However, water leakage was detected on the cotton undershirt inside jacket. 5 out of 8 jackets passed the normal rainfall condition(100l/m²/hr, 30 minutes). The newly developed rain tower system was able to evaluate the waterproofness of the jacket seams. It is recommended the further study on the detailed test conditions for the end use of the waterproof and breathable garments.

• Journal of the Korean Society of Radiology
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• v.14 no.3
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• pp.313-318
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• 2020

Since radon is an inert gas and is a monoatomic molecule, the size of one particle represents the size of an atom, which means that it has a radius of approximately 1 to 100 nm. Therefore, if the mask has a radius smaller than the size of general fine dust and ultra fine dust, but it is possible to block the inhalation of radon more than a certain amount, it is considered that the exposure through the inhalation of radon can be reduced through normal indoor wear. Accordingly, we would like to find out the radon blocking effect of a mask worn in everyday life. Looking at the reduction rate of radon for each mask, cotton masks decreased by 33.45%, medical masks by 33.50%, KF 80 masks by 35.12%, and KF 94 masks by 37.72%. It was found that the radon blocking effect of the cotton and medical masks was somewhat inferior to that of the KF mask, but the difference was not so great that the introduction of radon into the air could be blocked to a certain level by wearing a mask.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.5
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• pp.625-630
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• 2013

The friction behavior of a 60-${\mu}m$-thick anodic aluminum oxide (AAO) film having cylindrical nanopores of 45-nm diameter was investigated as a function of impregnated oil viscosity ranging from 3.4 to 392.6 cSt. Reciprocating ball-on-flat sliding friction tests using a 1-mm-diameter steel ball as the counterpart were carried out with normal load ranging from 0.1 to 1 N in an ambient environment. The friction coefficient significantly decreased with an increase in the oil viscosity. The boundary lubrication film remained effectively under all test conditions when high-viscosity oil was impregnated, whereas it was easily destroyed when low-viscosity oil was impregnated. Thin plastic deformed layer patches were formed on the worn surface with high-viscosity oil without evidence of tribochemical reaction and transfer of counterpart material.