• Fashion & Textile Research Journal
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• v.3 no.5
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• pp.486-491
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• 2001

The purpose of this study was to examine the effects of chemical finishes on performance characteristics of microfiber blend fabrics. A 60% polyester microfiber/40% cotton blend woven fabric was finished by ten chemicals: three silicone softeners, one fluorochemical, and their mixtures. Performance characteristics examined were abrasion resistance, and oil/water repellency. Chemical finishes containing dimethylpolysiloxane silicone performed better in fabric abrasion resistance than other chemicals. The correlation between abrasion wear and instrumental measures of fabric hand indicated that the breaking strength loss by abrasion related negatively to the coefficient of friction. This implied that the finished fabrics with lower surface frictional coefficient (slipperier) had higher breaking strength loss by abrasion. The microfiber structure of polyester did not appear to help in oil/water repellency due to the larger surface areas of the microfibers. The fluorochemical finished fabric had the most significant improvement on oil/water repellency. The silicone-only finishes, however, did not improve oil/water repellency. When mixed with the fluorochemical, silicone finishes showed improved oil/water repellency.

• Advances in materials Research
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• v.1 no.2
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• pp.129-146
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• 2012

Polycrystalline diamond is an ideal material for parts with micro-holes and has been widely used as dies and cutting tools in automotive, aerospace and woodworking industries due to its superior wear and corrosion resistance. In this research paper, the modeling and simultaneous optimization of multiple performance characteristics such as material removal rate and surface roughness of polycrystalline diamond (PCD) with ultrasonic machining process has been presented. The fuzzy logic and taguchi's quality loss function has been used. In recent years, fuzzy logic has been used in manufacturing engineering for modeling and monitoring. Also the effect of controllable machining parameters like type of abrasive slurry, their size and concentration, nature of tool material and the power rating of the machine has been determined by applying the single objective and multi-objective optimization techniques. The analysis of results has been done using the MATLAB 7.5 software and results obtained are validated by conducting the confirmation experiments. The results show the considerable improvement in S/N ratio as compared to initial cutting conditions. The surface roughness of machined surface has been measured by using the Perthometer (M4Pi, Mahr Germany).

• Advances in concrete construction
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• v.6 no.4
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• pp.363-373
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• 2018

Portland cement pervious concrete (PCPC) is an effective pavement material to solve or reduce the urban waterlogging problems. The Mechanical properties, the permeability, the abrasion resistance and the frost resistance of PCPC without fine aggregate were investigated. The increase of porosity was achieved by fixing the dosage of coarse aggregate and reducing the amount of cement paste. The results show that the compressive strength and the flexural strength of PCPC decrease with the increase of porosity. The permeability coefficient and the wear loss of PCPC increase with the increase of the porosity. The compressive strength and the flexural strength of PCPC subjected to 25 freeze-thaw cycles are reduced by 13.7%-17.8% and 10.6%-18.3%, respectively. For PCPC subjected to the same freeze-thaw cycles, the mass loss firstly increases and then decreases with the increase of the porosity. The relative dynamic modulus elasticity decreases with the increase of freeze-thaw cycles. And the lower the PCPC porosity is, the more obvious the dynamic modulus elasticity decreases.

• KSTLE International Journal
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• v.1 no.2
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• pp.113-117
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• 2000

The rotary-vane compressor has become one of the most successful types of compressors because of its mechanical reliability, compactness, and adaptability to moderately high-speed operation in virtually an unlimited range of sizes. However recently, the depletion of the ozone layer due to the current refrigerant(R22) has been getting worse, and it is one of the world's pressing issues. In this paper, we will discuss the use of R410a in the compressor of a room air-conditioner as an alternative refrigerant and air-conditioning system to R22, since R410a has greater refrigerant characteristics than R22. Miniaturization of the rotary compressor for the new refrigerant and air-conditioning system is also possible, which reduces the prime cost of production, hence R410a is naturally a better refrigerant. But to apply the new HFC refrigerant system in refrigeration and air-conditioning systems, a significant redesign of the current refrigerant system is also required, because as the refrigeration changes, lubrication characteristics vary. Close attention must be paid to friction force and energy loss due to friction and wear at many sliding areas.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.3
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• pp.68-75
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• 2021

The fuel economy is a key issue for the automotive industry due to environmental concerns. In particular, only 5-20% of the energy generated in a car using an internal combustion engine is used as power, and the remaining energy is dissipated due to friction with other parts. The main components in the reciprocating piston type compressors commonly used in general vehicles include shafts, swash plates, pistons, and cylinders, and severe friction loss occurs due to the contact of these components. Generally, the wear contact is the maximum between the shaft and cylinder and between the piston and swash plate. The friction of these parts may cause quality problems and deteriorate the durability. In this study, to reduce the frictional loss, a prototype with additional coating agents was produced. Moreover, an optimized design was generated, and performance, noise, and durability tests were conducted. A more durable product was successfully obtained.

• Composites Research
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• v.31 no.5
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• pp.260-266
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• 2018

This study investigates thermal and mechanical characterization of Hafnium carbide coating on the $C_f-C$ composites. The hafnium carbide coatings by vacuum plasma spray on the C/C-SiC composites are prepared to evaluate oxidation and wear resistance. We perform the thermal durability tests by thermal cycling at $1200^{\circ}C$ for 10cycles in air and investigates the weight change of each cycle. We also evaluate the wear and indentation behavior using tungsten carbide ball indenter as a mechanical evaluation. As a result, the HfC coating is beneficial to reduce of weight loss during thermal cycling test and improve the elastic property of C/C-SiC composite. Especially, the HfC coating improves the wear resistance of C/C-SiC composite.

• The Journal of Korean Academy of Prosthodontics
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• v.54 no.2
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• pp.140-145
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• 2016

Excessive occlusal wear causes loss of tooth structure, occlusal plane disharmony, impaired function and esthetic problems. Although the decrease of occlusal vertical dimension may be compensated by the growth of alveolar bone and tooth eruption, minimal increase of occlusal vertical dimension may be required for esthetics and retention of prosthesis. In this case, a 44-year-old male patient visited Seoul National University Dental Hospital with chief complaint of severe tooth wear and shade disharmony. Based on assessment of diagnostic wax-up, 3 mm increase of occlusal vertical dimension was determined. Removable occlusal splint and interim prosthesis was used to ascertain patient's comfort and adaptation. After the adaptation period, definitive prosthesis fabricated with full-contour monolithic zirconia were delivered and the patient was recommended to wear a nightguard device for prosthesis protection. This report presents a case of full mouth rehabilitation with the elevation of patient's occlusal vertical height, resulting in satisfactory esthetics and functions.

• Journal of dental hygiene science
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• v.16 no.1
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• pp.93-100
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• 2016

The purpose of this study was to compare the changes of retentive force in different stud attachment systems for implant retained overdenture. Two commercially available attachments with different retentive forces were investigated: Kerator (pink, blue, red) and O-ring (orange, red). Two implant fixtures were vertically embedded in base mountings. Five pairs of each attachment were evaluated. A universal testing machine was used to evaluate the retentive force of two attachments during wear simulation. Surface characteristics of each attachment system were evaluated with scanning electron microscopy. Five pairs of each attachment were evaluated. Kerator pink showed the highest initial retention. After 2,500 cycles of wear-simulation, Kerator pink noted the largest decrease in retention. According to results of surface analysis, Worn surfaces were obtained in matrices and patrices. Heavy wears were observed in matrices. After 2 year-wear simulation, most attachments exhibited retention loss. Attachments using different kind of material exhibited dissimilar surface alterations.

• The Journal of Korean Academy of Prosthodontics
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• v.55 no.2
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• pp.205-211
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• 2017

Loss of posterior support may cause extrusion of antagonistic teeth and excessive wear of remaining teeth which often leads to the destruction of the occlusal plane. In such cases, it is critical to verify the need to increase vertical dimension of occlusion (VDO). Should you increase VDO, provisionalization is crucial in evaluating function and esthetics. Double scanning technique is a useful method when fabricating definitive restoration that mimic provisional restoration. In this case, a patient with apparently no loss of VDO and insufficient interocclusal space for dental materials due to loss of posterior support and extrusion of antagonistic teeth was rehabilitated using double scanning technique.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.10b
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• pp.95-96
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• 2002

The operation of proceeding bearing in the conditions of misaligned axis of proceeding and bush leads to the load concentration on the bearing edges causing further mixed lubrication conditions, unstable operation and intensive wear of mating parts. For the design process of proceeding bearing the knowledge of static characteristics determined from the oil film pressure and temperature distribution is very important. For the 3-lobe proceeding bearing, the pressure, temperature and viscosity fields, load capacity, minimum oil film thickness, power loss, oil flow and maximum oil film temperature have been determined by iterative solution of the Reynolds', energy and viscosity equations. The paper introduces the results of theoretical investigations of static characteristics of 3-lobe proceeding bearing operating at misaligned axis of proceeding and bush. An effect of misalignment ratio, length to diameter ratio of the proceeding bearing, the lobe clearance ratio on the static characteristics was investigated. Laminar, adiabatic model of oil film for the solution of Reynolds, energy and viscosity equations was applied.