• Title/Summary/Keyword: Anti-wear

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Improvement of Anti-Corrosion Characteristics for Light Metal in Surface Modification with Sulfuric Acid Solution Condition (경금속 표면개질 시 황산 수용액 조건에 따른 내식성 개선 효과)

  • Lee, Seung-Jun;Han, Min-Su;Kim, Seong-Jong
    • Journal of Advanced Marine Engineering and Technology
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    • v.39 no.3
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    • pp.223-229
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    • 2015
  • Surface modification is a technology to form a new surface layer and overcome the intrinsic properties of the base material by applying thermal energy or stress onto the surface of the material. The purpose of this technique is to achieve anti-corrosion, beautiful appearance, wear resistance, insulation and conductance for base materials. Surface modification techniques may include plating, chemical conversion treatment, painting, lining and surface hardening. Among which, a surface modification process using electrolytes has been investigated for a long time in connection with research on its industrial application. The technology is highly favoured by various fields because it provides not only high productivity and cost reduction opportunities, but also application availability for components with complex geometry. In this study, an electrochemical experiment was performed on the surface of 5083-O Al alloy to determine an optimal electrolyte temperature, which produces surface with excellent corrosion resistance under marine environment than the initial surface. The experiment result, the modified surface presented a significantly lower corrosion current density with increasing electrolyte temperature, except for $5^{\circ}C$ of electrolyte temperature at which premature pores was created.

Survey on the Actual Wearing Conditions of Naval Duty Uniforms in Naval Vessels (해군 함상 근무복 개발을 위한 착용 실태 조사)

  • Lee, Hyo-Hyun;Shin, Sora;Lee, Joo-Young;Baek, Yoon Jeong
    • Fashion & Textile Research Journal
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    • v.17 no.4
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    • pp.646-656
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    • 2015
  • This study investigates the conditions of Korean naval duty and combat uniforms to develop a new design. Survey participants consisted of, 723 Sailors ($25.3{\pm}6.9yr$ in age, $43{\pm}53$ months in work experience, $174{\pm}6cm$ in height, $71{\pm}9kg$ in body mass) serving in the Korean Navy for over 12 months. The questionnaire consisted of 72 questions about anthropometric characteristics, preferred design, textiles, wear mobility, and subjective perceptions. The results showed that the preferred colors for future naval duty uniforms were blue in summer (69%) and black in winter (62%). Digital camouflage pattern (60%) and darker colors on the inside of shirt collar (87%) and the edge of sleeves (84%) were preferred. They favored more than one pocket on the upper arm and chest of the shirts (58%), narrower width around pant legs and hems than the current clothing (63%), self-controlled elastic waist (55%) and no cargo type pocket on the pants (45%). There were requirements to alleviate excessive heat stress in summer and to protect from the cold and wind in winter. Wrinkle-free (85%), anti-bacterial (78%), water-proof (75%), oil-proof (90%), and elastic (67%) textiles were preferred for Korean navy uniforms. These results will be applied to develop the next generation Korean navy uniforms.

The Aesthetic Qualities Featured in Vivienne Westwood's Works (비비안 웨스트우드(Vivienne Westwood)의 작품세계와 미적특성)

  • 염혜정
    • Journal of the Korean Society of Costume
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    • v.37
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    • pp.71-88
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    • 1998
  • This study will analyze the aesthetic qual-ities revealed in the work of Vivienne Wes-twood in order to gain an understanding of the development process and uniqueness of modern avant-garde fashion. Westwood gained worldwide recognition in the 1970s as the Punk movement emerged in London. Although her works have often been described as decadent and anti-establishment, her anarchic view of fashion has had a considerable influence on other designers, both in England and around the world. Vivienne Westwood's works can be divided into three periods. In the first period(1971∼78). Westwood design demonstrated elements which were variations of the subcultural Punk style. The noteworthy designs of this period included ripped T-shirts, bondage clothes, and fetishist accoutrements. In the second period(1979∼83), her designs expressed elements from ethnic and primitive tribal societies through the 'Pirate', 'Savages', 'Buffalo Girls', 'Witches' collections, which inspired New Romanticism movement. In the third period (1985∼ ), through works such as 'Mini-Crini'collection, her works identified elements from the old west and used materials such as crinoline and Harris tweed and contemporized them by rearranging the innovative technique. In the end the news synthesis helped formulate new ideas. The aesthetic qualities in Vivienne Wes-twood's works can bed identified with the following themes : Punkature, Erotic Intelligent-sia, Anarchic Collage. First, within Punkature, Westwood's ideas are at the forefront as her impact on the cut of clothes and creative detailing have been considerable. Also, while her ideas can be extreme, her clothes are wear-able, resulting in the synthesis of Punk and couture. Second, as Erotic Intelligentsia, Vivienne Westwood does not present sexuality as a straight forward attribute that fashion so often tends to do, but instead as a matter for inquiry, exploration and debate. She asserts that sexuality is always an interplay between the polarities of masculine and feminine, of dress and undress. Third, as Anarchic Collage, she has taken, juxtaposed, and transformed objects and symbols from dominant culture, like every modern subversive movement from Dada to Punk. She has continued this form of anarchic collage, mixing styles from various times and places, taking them out of their traditional context. From thiss viewpoint, Vivienne Westwood's works can be considered to be made up of past themes merged with is contemporary. The usage of contrasting elements such as Punk and couture to communicate her ideas visually or technically.

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The Impact of Functionalism on Changes of Women's Sportswear - Focusing on the first half of the 20th century - (기능주의가 여성 스포츠웨어 변천에 미친 영향 - 20세기 전반기를 중심으로 -)

  • Lee, Yu-Kyung
    • Journal of the Korea Fashion and Costume Design Association
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    • v.12 no.4
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    • pp.43-59
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    • 2010
  • In the first half of 20th century, there was an abrupt change in society and social values. Therefore, a demand for functional women's sportswear started to increase. This paper has attempted to investigate the impact of functionalism on women's sportswear in the first half of the 20th century. The following results were obtained: First, anti-tradition was observed. There was a tendency to be separated from the past and against tradition. It was tried to pursue freedom, getting away from corset and petticoat. Second, structural functions were targeted. In other words, precise and efficient shapes and simple silhouette and line were emphasized. Third, fitness of purpose was found. More liberal and comfortable design has been targeted. That's why a variety of functional pants have been designed instead of skirts. Fourth, utility and practicality were found. Elastic fabrics such as wool and jersey and sweater have commonly used in sportswear. A variety of new fabrics have been used and details such as flare, slit and pleats have been designed. Lastly, non-ornamentality was found. The beauty of simple shape was pursued by omitting details or eliminating unnecessary ornaments. Monochrome and dark color were preferred and a use of accessories has declined. The result of this paper could be used in establishing a theoretical framework on the impact on social change, values and art and helpful In modern women's sportswear design and marketing which have become more important.

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Microstructure and Properties of Ni-SiC Composite Coating Layers Formed using Nano-sized SiC Particles (SiC 나노입자를 이용하여 형성한 Ni-SiC 복합도금막의 미세구조 및 특성)

  • Lee, Hong-Kee;Son, Seong-Ho;Lee, Ho-Young;Jeon, Jun-Mi
    • Journal of Surface Science and Engineering
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    • v.40 no.2
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    • pp.63-69
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    • 2007
  • Ni-SiC composite coating layers were formed using two kinds of SiC nano-particles by DC electrodeposition in a nickel sulfamate bath containing SiC particles. The effect of stirring rate and SiC particle type on the microstructure and properties of Ni-SiC composite coating layers were investigated. Results revealed that the trend of deposition rate is closely related to the codeposition of SiC and the deposition rate. or nickel, and the codeposition behavior of SiC can be explained by using hydrodynamic effect due to stirring. The average roughness and friction coefficient are closely related to the codeposition of SiC and SiC particle size. It was found that the Victors microhardness of the composite coating layers increased with increasing codeposition of SiC. The composite coating layers containing smaller SiC particle showed higher hardness. This can be explained by using the strengthening mechanism resulting from dispersion hardening. Anti-wear property of the composite coating layers formed using 130 nm-sized SiC nano-particles has been improved by 2,300% compared with pure electroplated-nickel layer.

Development of Solid Lubricants for Oil-less Bush (오일리스 부시용 고체윤활제 개발)

  • Kong, Hosung;Han, Hung-Gu;Kim, Jin Uk;Kim, Kyoung Seok;Park, Jong Sik
    • Tribology and Lubricants
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    • v.35 no.2
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    • pp.87-93
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    • 2019
  • This work aims to develop a dry lubricant for oilless bush, especially a solid lubricant, thereby creating a coating method with improved properties of anti-friction and load-carrying capacity without oil lubrication. In this work, spherical-shaped powders of thermosetting resin such as polyimide (PI) are mixed with a binder matrix obtained by mixing a fluorocarbon compound resin such as Polytetrafluoroethylene (PTFE) or Ethylene tetra fluoro ethylene (ETFE) with itself or with a non-fluorocarbon thermoplastic resin such as Polyether ether ketone (PEEK). And these dry lubricant mixtures are thickly coated (200-300 mm in the thickness) on the inner surface of the bush by using a wet-typed air-spray deposition method. It was found that the load-carrying capacity of the solid lubricant for excavator bush (60 mm in diameter) that operates under a high load condition (at 40 MPa) is greatly improved owing to the spherical-shaped powders of thermosetting resin. In addition, the coefficient of friction at the sliding surface is also reduced less than 0.1. Thick coating also lowers the contact stress at the edge of a bush that results in better tribological performances. The result suggests that the lubrication performance and durability life of the bush can be remarkably improved even without lubrication (oil or grease).

Evaluation of the Filtration Efficiency and Facial Inhalation Resistance of Various Commercial Masks (시중에 판매되는 다양한 비인증 마스크의 분진 포집효율과 안면부 흡기저항 평가)

  • Kang, Sohyun;Kim, Soomin;Yoon, Chung Sik;Lee, Kiyoung
    • Journal of Environmental Health Sciences
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    • v.47 no.3
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    • pp.292-301
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    • 2021
  • Objectives: Wearing medical masks has been recommended since the declaration of coronavirus disease-19 (COVID-19) as a pandemic disease. Certified medical masks are evaluated according to filtration efficiency and facial inhalation resistance. However, some people use non-certified common masks. This study aimed to evaluate various non-certified commercial masks based on the certification criteria for medical masks. Methods: Twenty mask products (three anti-droplet, three disposable dental, eight fashion, three cotton, and three children's masks) were selected. For performance evaluation, filtration efficiency and facial inhalation resistance tests were conducted. The evaluation method followed the certification method for KF-certified masks of the Ministry of Food and Drug Safety (MFDS) and the N95 respirator of the National Institute for Occupational Safety and Health (NIOSH). Results: None of the 20 masks met the KF94 certification standard set by the MFDS. Four and three masks respectively met the KF80 certification standard and the N95 standard of NIOSH. Filtration efficiency was significantly higher in three-layer masks than in single layer masks. Pleated-type masks had higher filtration efficiency than cone-type masks. There was no correlation between the structure of masks and facial inhalation resistance. Conclusion: While no masks complied with the KF94 certification standard, a few masks met the KF80 and the N95 certification standards of NIOSH. Although some people wear non-certified commercial masks, protection from aerosols is not guaranteed by such masks. Evaluation of the protection efficiency of non-certified mask against microbiological infection is needed for the prevention of infectious disease.

The SIMDIST (Simulated Distillation) Analysis of Distributing Engine Oil (국내 유통 엔진오일 고온모사증류시험 분석)

  • Lim, Young-Kwan;Kim, Jiyeon;Kim, Jong-Ryeol;Ha, Jong-Han
    • Applied Chemistry for Engineering
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    • v.28 no.6
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    • pp.632-637
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    • 2017
  • The vehicle lubricant occupies upto 35% in a total lubricant market and engine oil occupies upto 77% in the vehicle lubricant market in Korea. A suitable quality management of the circulating engine oil is necessary for driver and engine protection. But, KS and synthetic engine oil products (involved over 30% synthetic oil) are exempt to any quality management under Petroleum and Alternative Fuel Business Act. It is also known that synthetic oils such as PAO (poly alpha olefin) have excellent properties and performance like anti-wear, varnish control and oxidation stability than those of mineral oils. For this reason, PAO has been used for an engine oil, rotary screw and reciprocating compressor in addition to heavy duty and other extreme service applications. In this study, our research group analyzed the chromatogram pattern for the mineral oil, PAO and mineral oil involved a typical ratio of PAO using SIMDIST (simulated distillation). In the SIMDIST chromatogram, the mineral oil showed a broad peak, while PAO showed a sharp typical peak. Also the oil with a large viscosity grade exhibited a long retention time due to the heavy molecular weight and high boiling point. In particular, the blended mineral oil with 20% PAO sample showed a distinctly different pattern compared to that of using the conventional mineral oil. For monitoring PAO contents in distributing engine oils, we analyzed the SIMDIST for 27 kinds of engine oils which were popularly sold in Korea. The analytic results indicate that all kinds of engine oils showed that PAO contents were below 20% in engine oil products. Moreover, the PAO titled product was found to have a small amount of PAO. Thus, we conclude that the related laws for the proper quality management of synthetic oils are needed to be established.

A Study on the Corrosion Prevention of the Integral Series Generator for Military Vehicles (군용차량용 엔진일체형 직렬 발전기 부식 방지에 관한 연구)

  • Kang, Tae-Woo;Kim, Seong-Gon;Shin, Cheol-Ho;Lee, Kye-Sub
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.20 no.6
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    • pp.74-79
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    • 2019
  • The military vehicle produces electric power through an engine-integrated serial hybrid generator that is connected to the engine and does not have a separate generator installation space. However, depending on the mechanical characteristics of the connection between the generator and the engine, iron oxide for internal rusting and lubrication grew scattered. The iron oxide is adhered to the starter to deteriorate the starting performance, and there is a problem that the noise of the leg due to wear of the gear is increased. To solve this problem, the connection spline material and the surface treatment of the engine were improved and the shape was changed to a grease sealing type to prevent the generation of iron oxide inside. As the shape of the generator connector composing the shafting system was changed, the integrity of the structure was confirmed through the torsional endurance test. In addition, through the actual vehicle load test, it was verified that no corrosion occurred during the target life span without internal corrosion. It was confirmed that the anti-scattering structure of the grease effectively suppresses the generation of iron oxide, thereby reducing the noise generated from the generator. In this paper, we propose a fundamental solution to the degradation of the starter and the noise generation by preventing the back corrosion caused by the serial hybrid generator installed between the engine and the transmission.

A Study on the Synthesis and Tribological Characteristics of Calcium Sulfonate Grease with Improved Low-temperature Performance (저온 성능이 향상된 Calcium Sulfonate 그리스의 합성 및 트라이볼로지 특성 연구)

  • Gwang-Tae Kim;Hyun-Ho Park;Chang-Seop Lee
    • Applied Chemistry for Engineering
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    • v.34 no.4
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    • pp.434-443
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    • 2023
  • We have investigated the performance improvement of grease by synthesizing calcium sulfonate grease as an alternative to lithium grease, which is widely used globally. Since the composition ratio of the grease, when manufactured, is usually 50% base oil and 50% thickener, using grease as a lubricant in a cryogenic environment is not encouraged due to its inferior low-temperature performance. In this study, we have synthesized three types of calcium sulfonate grease with paraffin oil and PAO-based base oil and thickener. Furthermore, lithium grease was synthesized via saponification with PAO-based base oil, lithium hydroxide, 12-hydroxystearic acid, and sebacic acid. We have measured low-temperature characteristics using a rheometer and low-temperature torque meter, and tribology characteristics were obtained using a four-ball lubricant tester and schwingung reibung verschleiß (SRV). As a result, the flow point of the calcium sulfonate grease synthesized with a PAO-based base oil and thickener was found to be -40℃, overcoming the existing calcium sulfonate grease's low-temperature limitation. Moreover, the synthesized calcium sulfonate grease showed low-temperature performance similar to that of lithium grease synthesized with PAO base oil, but superior anti-wear, extreme pressure, coefficient of friction, heat resistance, adhesion, and corrosion resistance. It is thus expected to commercially replace the existing lithium grease.