• 한국표면공학회지
• /
• 제44권3호
• /
• pp.95-104
• /
• 2011

Ti based nanocomposite films including V, Si and Nb (Ti-Me-N, Me=V, Si and Nb) were fabricated by hybrid physical vapor deposition (PVD) method consisting of unbalanced magnetron (UBM) sputtering and arc ion plating (AIP). The pure Ti target was used for arc ion plating and other metal targets (V, Si and Nb) were used for sputtering process at a gas mixture of Ar/$N_2$ atmosphere. Mostly all of the films were grown with textured TiN (111) plane except the Si doped Ti-Si-N film which has strong (200) peak. The microhardness of each film was measured using the nanoindentation method. The minimum value of removal rate ($0.5{\times}10^{-15}\;m^2/N$) was found at Nb doped Ti-Nb-N film which was composed of Ti-N and Nb-N nanoparticles with small amount of amorphous phases.

• 한국해양공학회지
• /
• 제32권6호
• /
• pp.492-501
• /
• 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.

• 한국해양공학회지
• /
• 제32권6호
• /
• pp.502-510
• /
• 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.

• 한국의류산업학회지
• /
• 제20권6호
• /
• pp.722-732
• /
• 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.

• 대한금속재료학회지
• /
• 제46권8호
• /
• pp.477-481
• /
• 2008

The secondary hardening and fracture behavior in P/M high speed steels bearing V content of 9 to 10 wt% have been investigated in terms of austenitizing temperature and precipitation behavior. Austenitizing was conducted at 1,100 and $1,175^{\circ}C$ of relatively low and high temperatures. Coarse primary carbides retained after austenitization were mainly V-rich MC type. They give a significant influence on hardeness and toughness, as well as wear resistance. Tempering was performed in the range of $500{\sim}600^{\circ}C$. The peak hardness resulting from the precipitation of the fine MC secondary carbides was observed near 520, irrespective of austenitizing temperature. Aging acceleration(or deceleration) did not occur with increasing austenitizing temperature because it mainly influences contents of V and C of matrix through the dissloution of coarse primary MC containing lots of V and C. The precipitation of secondary MC carbides, which also contain V and C, did not change the aging kinetics itself. In the 10V alloy containing much higher C content, the impact toughness was lower than 9V alloy, because of the larger amount of primary carbide and high hardness.

• 대한치과보철학회지
• /
• 제60권1호
• /
• pp.91-99
• /
• 2022

심한 치아 마모는 치료되지 않고 방치될 경우에 치아 구조물의 상실, 치수 합병증, 착색, 기능과 심미의 상실과 같은 여러 합병증 등을 야기한다. 본 증례의 환자는 전치부에서 특히 심한 치아마모를 보이며 수복공간 부족을 보이는 경우로 수직고경 거상을 동반한 전악 고정성 보철물로 수복을 하였다. 진단납형을 토대로 수직거상량을 결정하고 가철성 교합안정장치를 6주간 장착하여 적응도를 평가하였다. 이후 고정성 임시보철물을 수복함으로써 3달간 근신경계의 조화, 심미, 측두하악관절 등에 대하여 재평가하였다. 위와 같은 치료과정을 통해서 단일구조 지르코니아를 이용한 전악 고정성 보철물로 최종수복을 완료하였고 기능적, 심미적으로 안정적인 결과를 얻었기에 보고하는 바이다.

• International journal of advanced smart convergence
• /
• 제12권2호
• /
• pp.76-83
• /
• 2023

Squatting of agricultural work can cause musculoskeletal disorders due to excessive pressure and rotational force on the knee joint In order to improve the assistive chair used in squatting agricultural work so that it can be used in a narrow groove, it is intended to improve the musculoskeletal harm of squatting work by attaching a spring on the assistive chair. Therefore, in the presenty study, 3D drawing was done using ProEngineer (3D), and a mock-up was produced and tested. Using pro-Engineer, it was judged that it was rare for plastic to be broken by a spring, so the analysis was conducted with a focus on springs. It was found that the structure that can absorb the shock according to the rigidity of the tape spring and balance the body is that the power to withstand the load of the weight is distributed as a whole when five springs are used. Electromyography was measured using ME600 (Mega Electronics, Finland) Measuring equipment attached to the waist, thighs, calves, and shins. EMG values were measured and compared with the prototype in two ways, when the worker did not wear the product and when he wore an existing product on the market. As a result of the experiment when using the prototype, the maximum EMG value for each part is considered to be helpful in preventing musculoskeletal diseases as the amount of muscle used is reduced in the waist, thighs, calves, and shins.

• 복식문화연구
• /
• 제31권6호
• /
• pp.793-805
• /
• 2023

This study analyzes the body shapes of lower-body obese female adolescents and proposes a slacks pattern suitable for their body type. Lower-body obesity is a prevalent type of teenage obesity, and our proposals aim to improve consumer satisfaction in ready-to-wear clothes across this demographic. We first observe characteristics of obese lower bodies, noting significantly above-average thigh and hip circumference. These figures indicate a high degree of curvature in obese lower bodies, along with a large drop value. Leveraging this data, we develop a novel slacks pattern using 3D avatars in a virtual simulation system. The formulas for the main areas of the pattern are as follows: front waist girth W/4+0.75cm+0.5cm, back waist girth W/4+0.5cm-0.5cm, front hip girth H/4+1.25cm-0.5cm, back hip girth H/4+2cm+0.5cm, front crotch extension H/16+0.5cm, back crotch extension H/8+1cm. Results from appearance evaluations show that this pattern minimizes strain rate on the waist and hips, and its average score is significantly higher than that of an alternative pattern that was also evaluated. The minimized strain rate and high average score indicate that our pattern assigns a sufficient amount of space to the appropriate areas. Based on these results, we expect our research to inform slacks pattern development and production for obese consumers of all types.

• 한국분말재료학회지
• /
• 제30권5호
• /
• pp.415-423
• /
• 2023

With the increasing attention to environmental pollution caused by particulate matter globally, the automotive industry has also become increasingly interested in particulate matter, especially particulate matter generated by automobile brake systems. Here, we designed a coating composition and analyzed its mechanical properties to reduce particulate matter generated by brake systems during braking of vehicles. We designed a composition to check the mechanical properties change by adding Cr₃C₂ and YSZ to the WC-Ni-Cr composite composition. Based on the designed composition, coating samples were manufactured, and the coating properties were analyzed by Vickers hardness and ball-on-disk tests. As a result of the experiments, we found that the hardness and friction coefficient of the coating increased as the amount of Cr₃C₂ added decreased. Furthermore, we found that the hardness of the coating layer decreased when YSZ was added at 20vol%, but the friction coefficient was higher than the composition with Cr₃C₂ addition.

• 한국통신학회논문지
• /
• 제38C권12호
• /
• pp.1106-1113
• /
• 2013

치매와 같은 노인성 정신질환 환자들에게 운동량과 일광량은 환자의 투약량과 조절과 진료에 있어 중요한 단서가 된다. 따라서 환자들의 안전과 건강한 삶을 위해 일상생활의 건강정보 모니터링이 필수적이다. 이러한 서비스를 제공하기 위해 환자에게는 휴대가 간편하고 항상 착용 가능한 센서 디바이스와 데이터를 모니터링할 서버의 구성이 필요하다. 본 논문에서는 치매환자의 건강정보를 실시간으로 모니터링하고 관리하기 위해 환자가 착욕하는 시계형 디바이스(스마트 시계)와 서버시스템을 개발했다. 본 논문에서 개발한 스마트시계는 GPS, 가속도센서, 조도센서를 포함하며 환자의 위치 추적, 운동량, 일광량을 측정해 환자의 실시간 건강정보를 취득 할 수 있다. 서버시스템은 스마트시계를 통해 취득한 센서 데이터를 통해 의사, 보호자가 모니터링 할 수 있는 웹 서버와 센서 데이터의 분석 알고리즘을 포함한다. 본 논문에서 제안한 데이터 분석 알고리즘은 가속도센서를 통해 취득한 환자의 움직임에서 걸음 수를 검출해 운동량 정보를 취득하며 이를 검증하기 위해 빠른 걸음, 느린 걸음, 보통 걸음에 해당하는 3가지 경우로 실험한 결과 96%의 정확도를 보였다. 본 논문을 통해 개발된 치매환자를 위한 u-Health Care 시스템을 적용한다면 치매환자들에게 더 질 높은 의료서비스를 제공할 수 있을 것이다.