• Title/Summary/Keyword: Wear

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Mechanical Stability of TiN and DLC Coated Instrument of Pedicle Screw System (TiN 및 DLC 코팅된 척추경나사못시스템 수술기구의 기계적 안정성 분석)

  • Kang, Kwan-Su;Jung, Tae-Gon;Yang, Jae-Woong;Woo, Su-Heon;Park, Tea-Hyun;Jeong, Yong-Hoon
    • Journal of the Korean institute of surface engineering
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    • v.52 no.3
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    • pp.163-170
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    • 2019
  • Durability of instrument is one of the most important factor to ensure accurate treatment and decrease failure for the orthopedic surgical operation. Normally, a set-screw driver tip has been processed with hard coating for their higher durability and wear resistance. And several surface modification methods were obtained such as titanium nitride (TiN) coating, diamond like carbon coating, other nitriding, and etc. In this study, we have surface modified on set-screw driver tip with TiN and DLC, investigated whether the TiN and DLC coatings affect the mechanical properties and durability of the set-screw driver tip in the pedicle screw system. The surface morphologies were observed with scanning-electron microscopy (SEM), and the static/dynamic torsional properties were investigated with universal testing machine based on ASTM F543. Coating thickness of each coatings were commonly around $1^{\circ}C$. Static torsional stiffness, and ultimate torque values for DLC and TiN coated samples were significantly higher than those of non-coated sample by the pared T-test. Surface morphology of after the dynamic torsional test was more clean with less scratch or friction traces from DLC coating than that of TiN coating and non-coated sample.

Survey on Injuries during Snowboarding and Wearing Satisfaction to Develop Snowboard Protector (스노보드 보호대 개발을 위한 스노보딩 중 주요부상 및 보호대 착용만족도 조사)

  • Lee, Heeran;Hong, Kyung Hwa
    • Fashion & Textile Research Journal
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    • v.21 no.4
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    • pp.497-508
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    • 2019
  • Snowboarder accidents at ski resorts are increasing; therefore, it is essential to wear protective wrist, hip and knee protectors when snowboarding. However, most studies focus on the improvement of gear or expansion of safety facilities with few studies on protectors that directly safeguard the body from accidents caused by tumbling. Protectors currently on the market do not properly consider the needs of the users. Therefore, this study investigates the reality of usage and satisfaction rate of those that use snowboarding protectors along with factors deemed important upon wearing them to provide the grounds for the development of comfortable protectors. Subjects were 1,058 adults in their 20s to 40s. First, a survey was conducted regarding demographic traits as well as the wearing and purchasing of protectors. Second, 325 people that purchased and wore protectors were investigated in regards to the wearing satisfaction rate of current commercial protectors. The results showed that 86% of the 1,058 subjects wore protectors; knee protectors (72%), hip protectors (57%) and wrist protectors (38%). Important factors upon purchasing and wearing satisfaction were studied according to demographic traits, snowboarding experience, and number of snowboard rides for one season. As a result, the damage rate increased along with the number of snowboard rides for one season. Important factors considered when purchasing varied significantly according to sex, age, snowboarding experience, and favored slopes. The results of this study will help in the design of comfortable protectors for snowboarders.

Characteristics of eco-friendly design in contemporary children's fashion collection (현대 아동복 컬렉션에 나타난 친환경 디자인 특성)

  • Lee, Soyeon;Lee, Younhee
    • The Research Journal of the Costume Culture
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    • v.27 no.4
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    • pp.384-397
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    • 2019
  • The purpose of this study is to analyze the eco-friendly design characteristics of contemporary children's collections. Photos from FirstviewKorea were utilized for analysis; 29 brands were selected that included children's clothing collections featuring eco-friendly characteristics from 2007 to 2018. The results are as follows. First, naturalness was the most frequent characteristic of environmentally friendly children's collections. It was not conveyed in an eccentric way in any season, showed a relatively uniform distribution, and was seen in various ways, including printed on the fabric and expressed in $appliqu\acute{e}s$ and embroidery. Second, handcrafted features frequently changed according to seasonal trends. Various methods such as beading, embroidery, applique, sewing techniques, and handbags were used, which enhanced manual workability, discrimination from other designs. Third, traditionality is divided into the characteristics of ethnicity and revivalism. National traditions were expressed in the clothing and reflected the current generation while connecting to the past. Fourth, simplicity appeared in classic designs such as simple silhouettes, sparse decoration, natural colors, and comfortable dress length that is not tight on the body. Simplicity was not a frequent feature due to the characteristics of the children's clothing collections. Fifth, playfulness functioned to enhance the children's clothing's wear frequency. Although it was the least frequent of all the characteristics, it seemed to increase the design fun and the clothing's value by fusing with other characteristics such as handcraftedness and naturalness.

Variations in Tribology Factors of SM45C by UNSM Modification (SM45C재의 UNSM 처리에 의한 트라이볼러지 특성 변화)

  • Shim, Hyun-Bo;Suh, Chang-Min;Suh, Min-Soo;Amanov, Auezhan;Pyun, Young-Sik
    • Journal of Ocean Engineering and Technology
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    • v.32 no.6
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    • pp.492-501
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    • 2018
  • The following results were obtained from a series of studies to accumulate data to reduce the coefficient of friction for press dies by performing tribological tests before and after the UNSM treatment of SM45C. The UNSM-treated material had a nano-size surface texture, high surface hardness, and large and deep compressive residual stress formation. Even when the load was doubled, the small amount of abrasion, small weight of the abrasion, and width and depth of the abrasion did not increase as much as those for untreated materials. When loads of 5 N, 7.5 N, and 10 N were applied to the untreated material of SM45C, the coefficient of friction was approximately 0.76-0.78. With the large specimen, a value of 0.72-0.78 was maintained at a load of 50 N despite the differences in the size of the wear specimen and working load. Tribological tests of large specimens of SM45C treated with UNSM under tribological conditions of 100 N and 50 N showed that the frictional coefficient and time constant stably converged between 0.7 and 0.8. The friction coefficients of the small specimens treated with UNSM showed values between 0.78 and 0.75 under 5 N, 7.5 N, and 10 N. The friction coefficients of the SM45C treated with UNSM were comparable to each other.

Variations in Tribological Characteristics of SM45C by PVD Coating and Thin Films (SM45C재의 PVD코팅과 필름에 의한 트라이볼러지 특성)

  • Shim, Hyun-Bo;Suh, Chang-Min;Kim, Jong-Hyoung;Suh, Min-Soo
    • Journal of Ocean Engineering and Technology
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    • v.32 no.6
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    • pp.502-510
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    • 2018
  • In order to accumulate data to lower the friction coefficient of a press mold, tribological tests were performed before and after coating SM45C with a PVC/PO film and plasma coating (CrN, concept). The ultrasonic nanocrystal surface modification (UNSM)-treated material had a nano-size surface texture, high surface hardness, and large and deep compressive residual stress formation. Even when the load was doubled, the small amount of abrasion, small weight of the abrasion, and width and depth of the abrasion did not increase as much as those of untreated materials. A comparison of the weight change before and after the tribological test with the CrN and the concept coating material and that of the untreated material showed that the wear loss of the concept coating material and P-UNSM treated material (that is, the UNSM treated material treated with the concept coating) showed a tendency to decrease by approximately 55-75%. Concept 100N had a lower friction coefficient of about 0.6, and P-UNSM-30-100N showed almost the same curve as concept 100N and had a low coefficient of friction of about 0.6. The concept multilayer coating had a thickness of $5.32{\mu}m$. In the beginning, the coefficient of friction decreased because of the plasma coating, but it started to increase from about 250-300 s. After about 350 s, the coefficient of friction tended to approach the friction coefficient of the SM45C base metal. The SGV-280F film-attached test specimen was slightly pushed back and forth, but the SM45C base material was not exposed due to abrasion. The friction coefficient was 0.22, which was the lowest, and the tribological property was the best in this study.

Property Evaluation of Tungsten-Carbide Hard Materials as a Function of Binder (소결조제 변화에 따른 텅스텐카바이드 소결체 특성평가)

  • Kim, Ju-Hun;Oh, Ik-Hyun;Lee, Jeong-Han;Hong, Sung-Kil;Park, Hyun-Kuk
    • Journal of Powder Materials
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    • v.26 no.2
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    • pp.132-137
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    • 2019
  • Tungsten carbide (WC) hard materials are used in various industries and possess a superior hardness compared to other hard materials. They have particularly high melting points, high strength, and abrasion resistance. Accordingly, tungsten carbide hard materials are used for wear-resistant tools, cutting tools, machining tools, and other tooling materials. In this study, the WC-5wt.%Co, Fe, Ni hard materials are densified using the horizontal ball milled WC-Co, WC-Fe, and WC-Ni powders by a spark plasma sintering process. The WC-5Co, WC-5Fe, and WC-5Ni hard materials are almost completely densified with a relative density of up to 99.6% after simultaneous application of a pressure of 60 MPa and an electric current for about 15 min without any significant change in the grain size. The average grain size of WC-5Co, WC-5Fe, and WC-5Ni that was produced through SPS was about 0.421, 0.779, and $0.429{\mu}m$, respectively. The hardness and fracture toughness of the dense WC-5Co, WC-5Fe, WC-5Ni hard materials were also investigated.

Micro cutting process technology for micro molds parts (마이크로 금형 부품을 위한 마이크로 절삭가공 기술)

  • Ha, Seok-Jae;Park, Jeong-Yeon;Kim, Gun-Hee;Yoon, Gil-Sang
    • Design & Manufacturing
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    • v.13 no.1
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    • pp.5-12
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    • 2019
  • In this paper, we studied the micro tool deflection, micro cutting with low temperature, and deformation of micro ribs caused by cutting forces. First, we performed an integrated machining error compensation method based on captured images of tool deflection shapes in micro cutting process. In micro cutting process, micro tool deflection generates very serious problems in contrast to macro tool deflection. To get the real images of micro tool deflection, it is possible to estimate tool deflection in cutting conditions modeled and to compensate for machining errors using an iterative algorithm correcting tool path. Second, in macro cutting fields, the cryogenic cutting process has been applied to cut the refractory metal but, the serious problem may be generated in micro cutting fields by the cryogenic environment. However, if the proper low temperature is applied to micro cutting area, the cooling effect of cutting heat is expected. Such effect can make the reduction of tool wear and burr formation. For verifying this passibility, the micro cutting experiment at low temperature was performed and SEM images were analyzed. Third, the micro pattern was deformed by the cutting forces and the shape error occurred in the sidewall multi-step cutting process were minimized. As the results, the relationship between the cutting conditions and the deformation of micro-structure during micro cutting process was investigated.

A Study of Senior Men's Dress Form Development 3D Digital Technology (3D 디지털 기술을 활용한 시니어 남성 기성복 피팅용 드레스폼 개발에 관한 연구)

  • Do, Wolhee;Choi, Eunhee
    • Fashion & Textile Research Journal
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    • v.20 no.6
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    • pp.722-732
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    • 2018
  • This study was to develop a dress form that is highly representative of the body shapes of senior men in their 50s and 60s. And this research was compared the measurements and forms of three different dress forms available in the market, in order to analyze the body type and suitability and provide a standard for developing and utilizing the dress forms. After extracting the body shapes of the senior men's 3D shape, the body type that is curvature on the back prevalent among senior men, was chosen. The dress form was created as follows: 3D modeling and rendering, printing with a FDM-type 3D printer. The dress forms were 3D-scanned and the 3D data was analyzed - classification drop value, area deviation, compared horizontal section and vertical section. The results were as follows: This suggested that the area deviation amount at the chest and hip circumference levels was larger in the commercial products than in the dress form in this study, while that at the waist circumference level was larger in the dress form in this study. The vertical length of the lateral shoulder point-waist circumference was smaller, the side shape showed severe curvature on the back, and the waist circumference was larger in the senior men dress form than the commercial products. The dress form developed in this study reflected the body type of senior men and, therefore, were suitable for fitting when creating clothes for senior men.

Complex heat-treatment effects on as-built CoCrMo alloy (적층공정법으로 제작된 CoCrMo 합금의 복합열처리 효과)

  • Lee, Jung-Il;Kim, Hung Giun;Jung, Kyung-Hwan;Kim, Kang Min;Son, Yong;Ryu, Jeong Ho
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.28 no.6
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    • pp.250-255
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    • 2018
  • The CoCrMo as-built alloys prepared by 3D-printing process are studied on tensile strength, wear resistance, crystal structure and microstructure after complex heat-treatment including HIP. In this study, HIP treatment for removing micropores, ambient heat-treatment for formation of metal carbides, and solution heat-treatment for homogenization of the created metal carbides were tried and characterized for applying to artificial joint. The complex heat-treatment effects of the CoCrMo as-built alloys prepared by 3D-printing process were owing to the densification during HIP, formation of metal carbides and homogenization of the created metal carbides. The effects of the complex heat-treatment were confirmed by XRD, FE-SEM and EDS.

A Study on Clothing Purchasing Behavior of the Uzbekistan Students Staying in Korea(1) -The Clothing Wearing Condition and Factors Affecting on the Purchase Intention for Korean Fashion Products- (우즈베키스탄 유학생들의 의복 구매행동에 관한 연구(1) -의복 착용실태와 한국 패션제품 구매의도에 미치는 영향요인 분석-)

  • Lee, Okhee
    • Journal of Fashion Business
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    • v.23 no.1
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    • pp.25-36
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    • 2019
  • The purpose of this study is to offer a base line data to facilitate entrance of a Korean fashion company into the Uzbekistan market by conducting a survey of the Uzbekistan students in Korea. This is done in order to gather data on their clothes wearing condition and factors affecting the purchase intention for Korean fashion products. In this study, a survey was conducted to 260 Uzbekistan students in Korea. The results of the study were as follows: 1) Uzbekistan students bought clothes mainly from road shops and the Internet. They bought a lot of pants, shirts, jackets, jumpers, and preferred to wear black, white, blue, and red color. The dissatisfactory parts were shown in order of the width of trousers, the length of the sleeve, and the shoulder. The most unsatisfying products were the pants and T-shirt. 2) They considered the aesthetics of the fashion products evaluation criteria, the human source and the internet advertisement of the fashion information source, and the customer service of the store selection criteria. These students showed very favorable attitude towards Hallyu and Korea. In addition, their preference and purchase intention for KFP were high. 3) The level of satisfaction on 'quality', 'color', and 'care' of KFP were very high, but lowest on the 'size' and 'price' of the clothes. 4) It was revealed that the attitude toward Hallyu and Korea, the satisfaction and preference of KFP, and demographics have a significant impact on the intention toward purchasing fashion products.