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해양구조물 TMCP강의 피로균열진전거동에 미치는 용접이방성 및 과대하중의 영향
최성대,이종형,三澤啓志 韓國工作機械學會 2000 한국생산제조학회지 Vol.9 No.6
The effect of the welding for the offshore structure in the TMCP steel on the fatigue crack propagation rate and crack opening-and-closure behavior was examined. The welding anisotropy of the TMCP steel and crack propagation character-istics of the excessive loading were reviewed (1) It seemed that a heat which was generated by the welding made a compressive residual stress over the base metal, so fatigue crack propagation rate was placed lower than in case of the base metal. (2) In the base metal, an effect of the anisotropy which has an effect on fatigue crack propagation rate of the excessive load and the constant amplitude load was not found but in the welding material case, fatigue crack propagation rate of the excessive load in the specimen of the width direction was located in the retard side as compared with a specimen rolling direction. (3) A crack opening ratio of the used TMCP steel in this study was not changed after excessive loading but a retard phe-nomenon of crack propagation was observed. Consequently, it was thought that all of the retard phenomenon of crack propagation did not only a cause of the crack opening-arid-closure phenomenon.
고출력 다이오드 레이저를 이용한 SKD11 표면 열처리 특성
최성대,정선환,양승철,김잠규 한국공작기계학회 2007 한국공작기계학회 추계학술대회논문집 Vol.2007 No.-
An experimental investigation with high power diode laser system was carried out to study the effect of surface heat treatment on the SKD11. The surface heat treatment characteristics of the laser beam were evaluated using hardness tests, optical microscopy, X-ray diffraction and energy dispersive X-ray spectroscopy(EDS). Results indicated that the Hardness were changed by beam size, focal length, feed rates. The micro grain structure was observed retained austenite grain at hardened zone and globular cementite grain at fine grain zone and base metal zone by optical microscopy. The intensive X-ray diffraction patterns of (110)-(200)-(211) was detected on the surface and the hardened surface intensity level was bigger than the unhardened surface. The intensive X-ray diffraction patterns of (110)-(200)-(211) was detected hardened surface and the hardened surface distributed plenty of carbon density than metal zone.
최성대,鈴木 裕土,秋田 貢一,三澤 啓志 金烏工科大學校 2000 論文集 Vol.21 No.-
X-ray stress measurements of a single crystal silicon were carried out using characteristic X-rays. The χy-oscillation method was used as the oscillation method of a specimen for obtaining a perfect diffraction profile. Applied stress measurements of a single crystal silicon were carried out using characteristic X-rays. The stresses in three steps were applied on a specimen using a four-point bending device. The diffraction angles of three different diffraction planes were measured in each step using a φ800 ㎛ collimator, and the stresses were calculated from the peak shift. The measured stresses agreed well with the applied stresses evaluated using a strain gage. Therefore, the possibility of X-ray stress measurements of a single crystal was confirmed.
최성대,三澤啓志 금오공과대학교 산업기술개발연구원 2001 産業技術開發硏究 Vol.17 No.-
Fatigue crack growth tests were carried out using high manganese cast steel under constant amplitude loading. Average crystal grain sizes of the material are 200㎛ and 1000㎛. For this material, △Kth is about 8MPa√m which is quiet large as compared to the general structural steels and the crack growth rate is lower than the general structural steels especially in the low △K regsion. The reason of this behavior is crack closure due to fracture surface roughness and fretting oxide. The relationship between da/dN and the △Keff was represented by narrow band regardless of the stress ratio.
Fabrication of CNT/CMK3 Carbon Composites with High Electrical/Thermal Conductive Properties
최성대,이주현,박다민,김건중 대한화학회 2013 Bulletin of the Korean Chemical Society Vol.34 No.7
Composite materials of mesoporous carbon and carbon nanotubes were synthesized using Ni, Co and Pdloaded CMK3 via a catalytic reaction of methane and CO2. The CNTs grew from the pores of the mesoporous carbon supports, and they were attached tightly to the CMK3 surface in a densely tangled shape. The CNT/ CMK3 composite showed both non-graphitic mesoporous structures, and graphitic characteristics originating from the MWCNTS grown in the pores of CMK3. The electrochemical properties of the materials were characterized by their electrorheological effects and cyclic voltammetry. The CNTs/CMK3 composites showed high electrical conductivity and current density. The CNT/CMK3 or KOH-modified CNT/CMK3 particles were incorporated in a PMMA matrix to improve the thermal and electrical conductivity. Even higher thermal conductivity was achieved by the addition of KOH-modified CNT/CMK3 particles.
A Study on Module Design of Field Customization for Food Packaging System
최성대,임병남,이승진,김기만 한국기계가공학회 2023 한국기계가공학회지 Vol.22 No.4
A food-packaging system consists of a box former, case packer, and taping machine. The need for food-packagingfacilities is increasing, and the demand for factory automation has increased with advances in robot technology. However, current food-packaging systems suffer from incompatibility and high costs. These issues have made itdifficult for many companies to adopt these systems. This vicious cycle slows the pace of industrial growth. Tosolve this problem, it is necessary to design an optimal machine process and modularize the machine to establish amore efficient system. In this study, the structure of the food-packaging system was simplified and made compatible,enabling companies to utilize it efficiently and reducing modularity and price.
최성대,김낙교 대한전기학회 2005 전기학회논문지 D Vol.54 No.7(D)
In order to realize the speed control of an induction motor, the information of the rotor speed is needed. So the speed sensor as an encoder or a pulse generator is used to obtain it. But the use of speed sensor occur the some problems in the control system of an induction motor. To solve the problems, the appropriate speed estimation algorithm is used instead of the speed sensor. Also there is the limitation to improve the speed control performance of an induction motor using the existing speed estimation algorithm. Therefore, in this paper, intelligent speed estimator using Fuzzy-Neural systems as adaptive laws in Model Reference Adaptive System is proposed so as to improve the existing estimation algorithm and ,using the rotor speed estimated by the proposed estimator, the speed control of an induction motor without speed sensor is performed. The computer simulation and the experiment is executed to prove the performance of the speed control system using the proposed speed estimator.