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림프부종 치료기능 압박 소매용 Double Covered Yarn 제조 기술에 관한 연구
조대현,정태두,박은희,박영미,Cho, Daehyun,Jung, Taedu,Park, Eunhee,Park, Youngmi 한국섬유공학회 2021 한국섬유공학회지 Vol.58 No.3
This study aimed to develop a double-covered yarn (DCY) for compressed sleeves used to treat lymphedema that may occur after surgery in breast cancer patients. To improve pressure sensation, instead of using the existing nylon 66 and spandex combination, the DCY covering manufacturing process was improved by using new spandex and nylon 6 in the fiber combination. In addition, to determine the effect of the manufacturing parameters of DCY, which is a compression yarn, the behavior of changes in tensile stress and tensile strain according to the DCY manufacturing parameters and the side image of DCY by SEM were investigated. As a result, when the draft ratio of the spandex fiber used as the core yarn of DCY increased, the elongation area of DCY that could be stretched at low stress decreased. Under the same draft ratio condition, changing the fineness of the second covering yarn or spandex fiber had little effect on the mechanical properties of DCY. In addition, it was confirmed that the effect of the fineness and draft ratio of the spandex fiber and the fineness of the second covering yarn on the tensile stress and tensile strain of DCY was not very significant. Furthermore, it was found that the fineness of the spandex fiber and the second covering yarn were affected more than the draft ratio of the spandex fiber.
조대현(Daehyun Cho),김강민(Kangmin Kim),이진훈(Jinhun Lee),주석재(Seokjae Chu) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.6
Aluminium knuckles are being developed to replace the conventional cast iron ones for weight reduction of automobiles. Fatigue analysis and test are performed for aluminium knuckles made by hot isostatic pressing process. To obtain fatigue properties of the material, the fatigue specimens are prepared from knuckles and subjected to strain-controlled fatigue tests. The fatigue life of the knuckle under transverse load is predicted using MSC/FATIGUE. Finally, fatigue tests are performed for the knuckles and the fatigue life is compared with the MSC/FATIGUE results.
피스톤 스커트 표면의 트라이볼로지 거동에 미치는 표면형상과 코팅의 영향
조대현(DaeHyun Cho),정순오(SoonOh Chung),원영덕(YoungDuck Won),한만철(Mancheol Han),이영제(YoungZe Lee) 한국트라이볼로지학회 2008 한국트라이볼로지학회지 (Tribol. Lubr.) Vol.24 No.3
To reduce the friction losses and the wear amounts in the piston assembly two methods were proposed. One is the modification of surface profile of the skirt part. The surface coating is another method to protect the sliding surfaces. To modify the profile of the skirt surfaces the surfaces were ground to have three different shapes of profiles. Also, several coatings, such as graphite, TiN, and MoS₂, and DLC, were used to protect the surfaces of the piston skirts. The specimens of the skirt and the cylinder bores were tested with the reciprocating wear tester. SAE 5W40 engine oil was used in boundary lubrication regime. Among several coatings the graphite and DLC coatings were very effective to reduce the friction forces. Especially, DLC film represented much better tribological performances than the others. The friction coefficient of the graphite coating was the lowest, but the graphite coating was not effective to protect the surfaces.
그라파이트 박막과 DLC 박막을 증착한 디젤 엔진용 피스톤 스커트와 실린더 블록의 마찰 특성
조대현(DaeHyun Cho),이성애(SungAe Lee),이영제(YoungZe Lee) 한국트라이볼로지학회 2008 한국트라이볼로지학회 학술대회 Vol.2008 No.6
In this study friction and wear characteristics between piston skirts and cylinder bores were investigated using the reciprocating wear tester in SAE5W40 oil condition. The relative motion between a piston skirt and a cylinder liner in a real engine is considered to reciprocation wear tester. The cylinder blocks were used as reciprocation specimens, and the piston skirt samples with graphite and DLC coatings were used as fixed pin.
미끄럼 마찰시 생성되는 고탄소강의 열변형층이 트라이볼로지 특성에 미치는 영향
이성애(Sungae Lee),조대현(Daehyun Cho),이영제(Youngze Lee) 한국트라이볼로지학회 2009 한국트라이볼로지학회 학술대회 Vol.2009 No.6
There have been many studies about white layers generated in various manufacturing processes such as hard turning, grinding, reaming. There are two different opinions on its wear characteristics. It is considered to be tribological adventage in some instance, but should decrease wear resistance because of forming micro crack and void. In this study, Ball-on-Disk type tester was used for sliding test with SUJ2 specimen due to understand the effect of white layer on friction and wear property. Surface profiler was used for investigating change of surface profiles, and transformation of micro structure was observed by FE-SEM on cross section of specimen after chemical etching.
이동호(Dongho Lee),조대현(Daehyun Cho),변도영(Doyoung Byun) 대한기계학회 2022 대한기계학회 춘추학술대회 Vol.2022 No.11
Structural colors have a lot of potential in a wide range of display and optical applications. The implementation of structural color technology had been achieved using printed micro-dome structures based on the concept of total internal reflection, but it can face the resolution problem caused by conventional inkjet printing. There is a need for smart technologies to adopt new strategies for fabricating high-resolution structural colors for display. Here we demonstrated the concept of micro-dome structures based on EHD printing to achieve high resolution of micro-dome arrays by varying the printing parameters. Owing to the benefits, this can be the new paradigm of developing flexible, stretchable, and wearable displays based on EHD printing with high resolution.
이동호(Dongho Lee),조대현(Daehyun Cho),변도영(Doyoung Byun) 대한기계학회 2022 대한기계학회 춘추학술대회 Vol.2022 No.11
Structural colors have a lot of potential in a wide range of display and optical applications. The implementation of structural color technology had been achieved using printed micro-dome structures based on the concept of total internal reflection, but it can face the resolution problem caused by conventional inkjet printing. There is a need for smart technologies to adopt new strategies for fabricating high-resolution structural colors for display. Here we demonstrated the concept of micro-dome structures based on EHD printing to achieve high resolution of micro-dome arrays by varying the printing parameters. Owing to the benefits, this can be the new paradigm of developing flexible, stretchable, and wearable displays based on EHD printing with high resolution.