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DLC 코팅된 60E1(UIC60) 강의 건조 마찰에서의 미끄럼 마찰 거동
김종형(Jong-Hyoung Kim),정재일(Jae-Il Jeong),김재원(Jae-Won Kim),김태규(Tae-Gyu Kim),Chau Kian Hao,Willey Y. H. Liew,김석삼(Seock-Sam Kim) 대한기계학회 2020 大韓機械學會論文集A Vol.44 No.2
본 논문은 철도 레일용으로 사용되는 60E1 강 표면에 RF-PECVD 방법으로 Si-doped DLC 코팅과 non-doped DLC 코팅을 제작하여 ball-on-disk형 마찰시험기로 실험을 수행하고 DLC 코팅층의 경도와 마찰 특성을 평가하였다. 시험 결과, Si-doped DLC 코팅층의 경도가 non-doped DLC 코팅층보다 높게 나타났으며 마찰 계수는 낮게 나타났다. SEM 사진의 미시적 마찰면의 관찰 결과, non-doped DLC면에는 표면균열과 응착에 의한 마찰면이 관찰되었고, Si-doped DLC의 마찰면은 응착 유동에 의한 응착과 이착이 주된 마찰 메카니즘이었다. In this study, the nano-hardness and frictional behavior of non-doped DLC (diamond-like carbon) and Sidoped DLC coated 60E1 steel deposited by RF-PECVD method were investigated. The results showed that Si-doped DLC exhibited higher nano-hardness and lower friction coefficient than the non-doped DLC from ball-on-disk type tribometer. By using SEM (scanning electron microscope), SEM images showed friction mechanism of the base material was adhesion and that of DLC showed adhesion and brittle fracture. owever, Si-doped DLC showed adhesion friction and transfer layer of DLC to counterpart.
김종형,Noritsugu Umehara,Hiroyuki Kousaka,Mamoru Shimada,Mitsuru Hasegawa 대한기계학회 2010 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.24 No.1
Adhesion between rubbers and metals is often the main cause of machine trouble. Therefore, efficient utilization of rubber in dynamic and static applications requires the modification of the adhesion property of the rubber surface without affecting the bulk characteristics. In this work, we have studied the mechanism of the reduction in adhesion force between medical rubber, chloride-isobutene-isoprene rubber (CIIR), and stainless steel by using surface wave-excited plasma treatment of the rubber surface with oxygen and argon gases. Experimental results showed that surface roughness derivations increased by about 10 times across the treatment, at maximum, corresponding to the increase in time. In addition, the micro-scale Young’s modulus of treated CIIR sheet increased by about 6.3 times at maximum from that of the untreated CIIR sheet. These changes in Young’s modulus and roughness at the surface of CIIR sheet are considered to be the main reasons for the plasma-assisted reduction of adhesion force between stainless steel ball (SUS 440C, JIS) and CIIR sheet.
김종형,이승재 대한교통학회 2001 대한교통학회지 Vol.19 No.1
현재까지의 관측교통량기반 수요추정법은 단일차종(singleclass)기반 연구가 대부분을 차지하고 있다. 그러나 현실 교통망에서는 여러 차종이 혼재되어 교통수요나 흐름을 만든다. 즉, 기존의 관측교통량기반 수요추정법은 PCE(Passenger Car Equivalent) 환산을 통한 여러 개의 차종O/D 및 관측교통량을 승용차 단위로 전환하여 하나의 O/D 및 관측교통량으로 만들어 O/D를 추정하고, 최초의 PCE환산이전 차종별 O/D의 고정비율과 관측교통량 고정비율로 곱해 차종별 O/D 및 관측교통량으로 나누어 분석하는 것이 일반적인 방법이었다. 즉, 다차종기반분석법은 각각의 차종별 O/D에 대한 노선선택비율을 각각 계산하고, 그에 따른 목적함수 감소방향인 gradient를 또한 각각 계산하여 차종별 추정력을 극대화하는 것이 그 장점이라고 할 수 있다. 따라서, 본 연구에서는 단일차종기반추정법을 다차종기반추정법으로 확장하여 차종간 혼잡을 고려한 보다 현실적인 수요추정기법을 마련하는 것이 본 연구의 목적이라고 하겠다. Until now, though most of the studies related to demand estimation method using traffic counts use methods based on singleclass, travel demands or flows are made by mixing various vehicles in real networks. In general, existing demand estimation methods based on traffic counts estimate O/D by converting a multiclass O/D matrix and traffic counts into a singleclass O/D matrix and traffic counts through PCE conversion, and analyze a O/D matrix by dividing into a multiclass O/D matrix and traffic counts after multiplying an estimated O/D matrix by the fixed ratio of a singleclass O/D matrix and traffic counts before PCE conversion. However, the merits of a demand estimation method based on multiclass calculate each route choice ratio about multiclass O/D, and maximize the estimation capability of multiclass by calculating each gradient, the reduction direction of objective function. Therefore, this study aims to establish a demand estimation method which considers congestion between vehicle and vehicle by using multiclass instead of singleclass.
김종형 ( Jong Hyung Kim ),오지선 ( Ji Seon Oh ),김동민 ( Dong Min Kim ),허성재 ( Seong Jae Huh ),임경훈 ( Kyung Hun Lim ),도기원 ( Gi Won Do ),홍순형 ( Soon Hyung Hong ),최승원 ( Seung Won Choi ) 대한류마티스학회 2010 대한류마티스학회지 Vol.17 No.1
Periorbital edema is a rare manifestation of systemic lupus erythematosus (SLE). We describe here a patient with bilateral periorbital edema as a presenting symptom of SLE. A 23-year-old woman was admitted for a sudden onset of severe periorbital edema that developed 7 days previously. On the basis of the malar rash, arthritis of the right hand and left wrist, leukopenia, proteinuria and the positive anti-nuclear and anti-dsDNA antibodies, she was diagnosed with SLE. Kidney biopsy revealed lupus nephritis (WHO class IV). After treatment with high dose of steroids, intravenous cyclophosphamide and daily hydroxychloroquine, her symptoms resolved, including the periorbital edema. She was discharged with prescriptions for prednisolone and hydroxychloroquine and she remains well.
김종형(Jong Hyeong Kim),Chanh D. Tr. Nguyen 제어로봇시스템학회 2013 제어·로봇·시스템학회 논문지 Vol.19 No.11
Shape recognition of solder ball bumps in a BGA (Ball Grid Array) is an important issue in flip chip bonding technology. In particular, the semiconductor industry has required faster and more accurate inspection of micron-size solder bumps in flip chip bonding as the density of balls has increased dramatically. The difficulty of this issue comes from specular reflection on the metal ball. Shape recognition of a metal ball is a very realproblem for computer vision systems. Specular reflection of the metal ball appears, disappears, or changes its image abruptly due to tiny movementson behalf of the viewer. This paper presents a practical shape recognition method for three dimensional (3-D) inspection of a BGA using a 5-step ring illumination device. When the ring light illuminates the balls, distinctive specularity images of the balls, which are referred to as“iso-slope contours” in this paper, are shown. By using a mathematical reflectance model, we can drive the 3-D shape information of the ball in aquantitative manner. The experimental results show the usefulness of the method for industrial application in terms of time and accuracy.