Microstructure and properties of cross-roll rolled and heat treated metastable TiNbSn alloy.

Jung, Taek-Kyun,Choi, Ho-Joon,Kim, Kyung-Taek,Shin, Young-Chul,Lee, Hyo-Soo,Lim, Sung-Chul,Kwon, Hyouk-Chon,Hanada, Shuji American Scientific Publishers 2014 Journal of Nanoscience and Nanotechnology Vol.14 No.10

<P>A (Ti-35mass%Nb)-4mass%Sn alloy was cross-roll rolled with a reduction ratio of 70% in which the roll axes are tilted by 5 degrees away from the transverse direction of the rolled sample and then aged at 250 degrees C for 2 h. Cross-roll rolling was found to increase yield strength and Young's modulus, simultaneously. Yield strength was higher in cross-roll rolled than in conventionally rolled at same reduction ratio. Yield and tensile strength further increased by a low temperature ageing by ψ precipitation hardening and microstructure refinement. Yield and tensile strength of the aged 70% cross-roll rolled sample were higher than those of the aged 70% conventionally rolled one.</P>

복합레진의 수리 시 표면처리가 결합강도에 미치는 영향

최정인,김영재,김정욱,이상훈,김종철,한세현,장기택 大韓小兒齒科學會 2008 大韓小兒齒科學會誌 Vol.35 No.4

본 연구의 목적은 표면처리가 기존의 레진과 새로운 레진 사이의 전단결합강도에 미치는 영향을 평가하는 것이다. 준비된 레진 시편을 6군으로 임의로 배분하여 각각의 표면처리를 한 후 수리용 레진을 축조하였다. 일주일간 보관 후 전단결합강도를 측정하였고 일원분산 분석법으로 통계처리하여 다음과 같은 결과를 얻었다. 1. 3군과 4군(air abrasion)은 1군(산부식)에 비해 전단결합강도가 유의하게 높게 나타났다(p<0.005). 5군과 6군(diamond bur)은 1군(산부식)에 비해 높은 전단결합강도를 나타냈으나 통계적으로 유의하지 않았다(p<0.005). 2. 2군(자가부식 접착제)은 1군(산부식)에 비해 전단결합강도가 낮게 나타났으나 유의한 차이는 없었다(p<0.005). 3. 3군(air abrasion)과 4군(air abrasion +산부식)에서 전단결합강도의 차이는 유의하지 않았다(p<0.005). 4. 5군(diamond bur)과 6군(diamond bur+산부식)에서 전단결합강도의 차이는 유의하지 않았다(p<0.005). 결론적으로,복합레진의 수리 시 air abrasion으로 표면처리를 했을 때의 결합강도가 가장 높았고,산부식 방법과 처리여부는 수리강도에 유의한 영향을 미치지 않았다. The purpose of this study was to evaluate the effect of surface treatment on the shear bond strength between new and old composite resin. The prepared resin specimens were separated 6 groups, and each group then received a different surface treatment. Then the repair material was added. Shear bond strengths for repair were measured after 7 days and the results were analyzed by using one way ANOVA. The results were as follows ; 1. Group 3, 4(air abrasion) showed significantly higher shear bond strength than Group l (phosphoric acid)(p<0.05). Group 5, 6(diamond bur) showed higher bond strength than Group l(phosphoric acid) but not significantly different(p<0.05). 2. Group 2(self-etching adhesive) showed lower shear bond strength than Group 1 (phosphoric acid) but not significantly different (p<0.05). 3. There was no statistically significant difference between Group 3 (air abrasion) and Group 4(air abrasion + etching). 4. There was no statistically significant difference between Group 5(diamond bur) and Group 6(diamond bur+etching). In conclusion, the surface treatment with air abrasion resulted in higher repair bond strength than other methods. Repair bond strength was not significantly affected by acid etching.

평면운동모델을 이용한 LMG 상에서 이송되는 Cross Head의 사행동 해석

최영휴,김성훈,정택수 國立 昌原大學校 産業技術硏究所 2002 産技硏論文集 Vol.16 No.-

In this paper, a simple 2 D.O.F. planar motion model is proposed in order to analyze the snake motion of a cross head assembly travelling on linear huide rails. In the proposed mathematical model, the head assembly and a ball screw are assumed to be rigid, but the rear-panel of the machining center is assumed to be flexible. The equations of motion of the proposed model are derived and solved by Runge-Kutta method to determine vibration responses of the head assembly due to some applied traction forces.

노드 채색문제에 대한 기존 해법의 분석 및 분류

최택진,명영수,차동완 한국경영과학회 1993 한국경영과학회지 Vol.18 No.3

The node coloring problem is a problem to color the nodes of a graph using the minimum number of colors possible so that any two adjacent nodes are colored differently. This problem, along with the edge coloring problem, has a variety of practical applications particularly in item loading, resource allocation, exam timetabling, and channel assignment. The node coloring problem is an NP-hard problem, and thus many researchers develop a number of heuristic algorithms. In this paper, we survey and classify those heuristics with the emphasis on how an algorithm orders the nodes and colors the nodes using a determined ordering.

광 교환 기술을 이용한 ATM 백본 네트워크

최영복,김경연,고성택,김경식 濟州大學校 産業技術硏究所 1997 산업기술연구소논문집 Vol.8 No.2

The B-ISDN(Broadband-Integrated Service Digital Network) transports various multimedia information effectively. So optical switching networks which consist of optical transmission links and photonic switching systems are noticeable as a way of a large capacity communication. In this paper. we propose optical packet switching networks which will be used as the backbone network of national high speed communication networks which are operated a way of ATM (Asynchronous Transfer Mode). The B-ISDN transport networks are composed of two-layered networks such as regional networks and a backbone network. The regional network is a n average ATM transport network. The optical backbone network gathers fixed length of several AThI cells which come from regional networks. attaches an optical header. and completes an optical packet, And then the network switches and transports with high speed. That is. the backbone network is a transparent optical packet network. The passing speed of signal in the photonic switch is rapid, but the switching speed is limited and the processing speed of the switching controller which consists of electronic circuit is limited. So the optical packet which consists of multi-ATM cells is able to overcome it in the optical backbone network. The performance evaluation by the computer simulation shows us the efficiency of the proposed way of optical packet switching.

신경망 시각인식을 위한 양안영상 전처리 시스템 구현

최진우,김영택 慶星大學校 1998 論文集 Vol.19 No.2

To design a computer vision system, the theory for humans visual perception in biological brain and cognitive science is referred in respect that those mechanism can be a good model for a machine vision system. Human's hierarchical, parallel and distributed processing on a stereo vision structure is studied to simulate visual perception. The way of integrating a stereo visual information processing model of V₁, V₂with the neural network theory is a major concern of this paper. Especially, experiments on a stereo image processing model for complex cell of V₂has been implemented.

北韓法理論과 支配體制의 構造的 特徵에 관한 儉討 : 92年의 改正憲法을 中心으로 by amended Constitutional Law in 1992

崔榮澤 서경대학교 1992 論文集 Vol.20 No.-

體育特技者의 肺機能과 運動後 恢復期의 血液가스의 變化

崔圭澤,朴載植,黃樹寬,朱永恩 慶北大學校 1985 論文集 Vol.39 No.-

The pulmonary function and changes of blood gas tensions and pH in the athletes have been reported but are fragmentary as to require more complete studies including all the pulmonary parameters and blood gas tensions especially at the early part of 20 years of age. This study was aimed to elucidate the pulmonary function at the rest and the changes of venous blood gas tension and pH after the exercise in the athletes of physical education students. The subjects chosen for this study were 15 athletes of physical education students (special group) of 21-25 years of age. The athletes had at least four years of exercise careers, and were compared with 12 non-athletes of physical education students (general group) who had not been subjected to any form of rigorous training program. All the subject were directed to perform running on the treadmill for three minutes under the condition of 15% grade and 5 MPH. The venous blood samples were taken at the rest as well as at 0, 5, 10 and 20 minutes after the exercise to check the changes of Pco_2, Po_2 and pH during the recovery period. The venous blood Pco_2, Po_2 and pH were determined using the Model 175 Automatic Blood Gas Analyzer by Corning Co., and the pulmonary function using the computerized spirometer. The results obtained were compared with the general group and summarized as follows: The special group exhibited higher values of the pulmonary function except FVC compared with the general group, and particularly FEV_0·5% and FEV_1% were significantly different. The venous Po_2 was decreased immediately after the exercise, but increased during the recovery period. The special group generally showed higher oxygen partial pressure than the general group. The venous Pco_2 in contrast to the oxygen increased immediately after the exercise, but decreased during the recovery period. The special group showed lower carbon dioxide partial pressure. Blood pH was significantly decreased from the resting value after the exercise and returned to the resting value at 20 minutes. In the special group, however, the change of pH was less than in the general group.

학과평가 및 교원업적평가 운영방안

최병태,서승교,박영순,이택영 대구산업정보대학 2000 논문집 Vol.14 No.2

中國의 經濟改革과 法制整備에 관한 檢討

崔榮澤 서경대학교 1994 論文集 Vol.22 No.1