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Lee, Chul‐,Ho,Kim, Yong‐,Jin,Hong, Young Joon,Jeon, Seong‐,Ran,Bae, Sukang,Hong, Byung Hee,Yi, Gyu‐,Chul WILEY‐VCH Verlag 2011 ADVANCED MATERIALS Vol.23 No.40
<P>Inorganic‐based flexible light‐emitting diodes (LEDs) using single‐crystalline GaN/ZnO coaxial nanorod heterostructures grown directly on large graphene films are reported on page 4614 by Gyu‐Chul Yi and co‐workers. The LEDs demon‐strate reliable operation in a flexible form, with no significant degradation in their electroluminescent or electrical characteristics. This approach provides a general and rational route to develop many different inorganic optoelectronics in flexible or stretchable forms. </P>
Cone beam형 전산화단층영상에서 골의 형태와 밀도의 평가
홍상우,김규태,최용석,황의환 대한구강악안면방사선학회 2008 Imaging Science in Dentistry Vol.38 No.1
Purpose : Diagnostic estimation of destruction and formation of bone has the typical limit according to capacity of x-ray generator and image detector. So the aim of this study was to find out how much it can reproduce the shape and the density of bone in the case of using recently developed dental type of cone beam computed tomography, and which image is applied by new detector and mathematic calculation. Materials and Methods : Cone beam computed tomography (PSR 9000N, Asahi Roentgen Ind. Co., Ltd., Japan) and soft x-ray radiography were executed on dry mandible that was already decalcified during 5 hours, 10 hours, 15 hours, 20 hours, and 25 hours. Estimating and comparing of those came to the following results. Results : The change of inferior border of mandible and anterior border of ramus in the region of cortical bone was observed between first 5 and 10 hours of decalcification. The reproduction of shape and density in the region of cortical bone and cancellous bone can be hardly observed at cone beam computed tomography compared with soft x-ray radiography. The difference of decrease of bone density according to hours of decalcification increase wasn’t reproduced at cone beam computed tomography compared with soft x-ray radiography. Conclusion : CBCT images revealed higher spatial resolution. However, contrast resolution in region of low contrast sensitivity is the inferiority of images’ property.
홍성오,조규재 朝鮮大學校 機械技術硏究所 1999 機械技術硏究 Vol.2 No.2
One of the important technical issues is how to decrease thermal expansion of ballscrew in proportion to the increase of machining speed, when measuring force of stretch of ballscrew, since not only actual expansion and the value of bending have to be considered, it's impossible to define that exact value of expansion. In addition, support bearings of ballscrew gain considerable force in axial direction. It also generates thermal expansion on the ballscrew, and deteriorates the bearings. In conclusion, it's impossible to give the pretension enough to absorb the all elongation due to thermal expansion generated during machine running. If gave, bed, column and saddle are all bent to change machine accuracy, and the support bearings of ballscrew are damaged. The purpose of this paper is to study the pretension of support bearing of ballscrew in machine tool.
Compensation(보정), Positioning accuracy(위치 정밀도)
홍성오,홍순남,조규재,전언찬 東亞大學校 1997 東亞論叢 Vol.34 No.-
Thermal expension of the ball screw in semi-closed loop type CNC lathe directly introduced positioning errors along the travel axis In this paper the thermal displacement of the ball screw is estimated by using macro variables. The estimated displacementes of the ball screw are given to the NC in the form of pitch error compensation data into time interval.The thermal behaviour of the ball screw of the CNC lathe under the constant driving conditions was measured to examine the effectiveness of this compensation method. The results showed that thermal displacements of the ball screw were the positioning accuracy could be maintained to better than 6μm which using this compensation.
유한요소법을 이용한 고주파 열처리시 안내면 변형에 관한 연구
홍성오,조규재 한국공작기계학회 2002 한국생산제조학회지 Vol.11 No.3
Finite element program(ANSYS) estimated thermal deformation quantity in high frequency heat treatment process of a machine tool feed drive system slideway and apply deformation quantity in roughing process. Having processed the heat treatment, minimizing methods of the quantity of deformation heat treatment process. Having done heat treatment with high frequency after taper processing with considering the existed heat treatment generating the quantity of deformation, existed quantity of deformation can be reduced down to 80%, consequently productivity and material saving can be achieved. When high frequency heat treatment finite element method estimated deformation quantity at difference temperature and time. it is progress at cost down and saved time.
CNC 선반에서 볼 나사 열변형에 따른 위치결정 정도 개선에 관한 연구
홍성오,조규재,김재열 한국공작기계학회 1999 한국생산제조학회지 Vol.8 No.1
Thermal expansion of the ball screw can directly affect the accuracy of positioning along the ravel axis in the semi-closed loop type CNC Lathe. In this paper, use of MACRO variables can make the thermal displacement of the ball screw estimated. Also, the estimated displacements of the ball screw are controlled by calculation the interval of pitch error rate in the Numerical Control(NC). Under the constant operating conditions, the thermal expansion of the ball screw was measured to confirm the effectiveness of the compensation method in the CMC Lathe. By using this method the results show that the thermal displacement of the ball screw could be reduced to 20% compared with ordinary method.
Auto Line에서 공작기계 열변형에 따른 위치오차 억제에 관한 연구
홍성오,조규재 朝鮮大學校 機械技術硏究所 1999 機械技術硏究 Vol.2 No.1
Development of high speed feed drive system has been a major issue for the past few decades in machine tool industries. The reduction of the tool change time as well as rapid travel time can enhance the productivity. However, the high speed feed drive system generates more heat in nature, which leads thermal expansion that has adverse effects on the accuracy of machined parts. The detail of the model proposed is described in the paper together with the experimental methodologies using a proposed compact measurement system to examine the validity of the proposed approach. The results showed the machining accuracy could be maintained to better than ±5㎛ while using this sensor.
뉴로 컴퓨팅 시스템 시뮬레이션 언어 개발 및 응용환경의 구축
홍규완,김정수,이수동 울산대학교 1995 공학연구논문집 Vol.26 No.1
대부분의 신경망 시뮬레이션 프로그램은 기존의 언어(C,PASCAL,FORTRAN등)로 구현되었다. 기존의 언어들은 신경망구조와 신경망의 동적행위를 제어하는 데 적합한 자료구조와 문장들을 가지고 있지 않기 때문에 시뮬레이션 프로그램을 작성하거나 모델의 변경에 어려움이 많다. 본 논문에서는 신경망 시뮬레이션 프로그램을 작성하는데 적합한 언어를 설계하였다. 특히 제안된 언어는 신경망 구조를 쉽게 표현할 수 있고 신경망의 동작행위를 효율적으로 기술하기 위하여 층마크로 정의 개념을 도입하였다. 언어는 두개의 DIVISION으로 구성되었다. 하나는 망구조를 기술하기 위한 NETWORK STRUCTURE DIVISION이고 다른 하나는 신경망의 행위를 제어하는 PROCEDURE DIVISION이다. Most of neural network simulation programs have been implemented with the conventional computer languages. It is difficult to implement simulation programs and is various to build neural network, because the languages have not data structures and statements suitable for expressing neural network structures and controlling neural behaviors. This paper describes a neural network simulation language, specifically designed for the development and modeling of neural network applications. It has a layer macro definition concept to express the arbitrary network structures and dynamic neural behaviors easily. It consists of the two divisions. First division describes the network structures. Second division controls the network behaviors.