• 대한기계학회논문집
• /
• 제7권1호
• /
• pp.28-35
• /
• 1983

Quantitative analysis have been carried out on the micro-cracks on the surface and into the depth of unnotched smooth mild steel specimen under cyclic stains by rotating bending fatigue tests. Some of the results are; (1) Cracks initiate at the early stage of fatigue life N$_{I}$/ N$_{f}$=10 to 20%, and propagate during the rest of fatigue life. (2) Coalescence of highly crowded small fatigue cracks of random distribution seems to induce the final fracture at higher stress level. (3) The curves of crack initiation and the equal crack length on the graph of stress versus number of cycles are parallel to the S-N curve. (3) The curves of crack initiation and the equal crack length on the graph of stress versus number of cycles are parallel to the S-N curve. (4) The distributions of micro-surface crack length and depth show the composite Weibull distributions which are approximated to two straight lines separated by the value of transient region between stage I and stage II crack.k.k.

• 한국정밀공학회지
• /
• 제17권3호
• /
• pp.158-164
• /
• 2000

In recent year, desire and request fer micro automation are growing rapidly covering the whole range of the industry. This has been caused mainly by request of more accurate manufacturing process due to a higher density of integrated circuits in semiconductor industry. This paper presents a six d.o.f fine motion stage using magnetic levitation technique, which is one of actuating techniques that have the potential for achieving such a micro motion. There is no limit in motion resolution theoretically that the magnetically levitated part over a fixed stator can realize. In addition, it Is possible to manipulate the position and the force of the moving part at the same time. Then, the magnetic levitation technique is chosen into the actuating method. However, we discuss issues of design, kinematics, dynamics, and control of the proposed system. And a few experimental results fur step input are given.

• 소성∙가공
• /
• 제13권3호
• /
• pp.273-278
• /
• 2004

This paper subscribes the measurement system that can position the target to measure by moving 2-axis stage, which is controlled by the data from image processing technique. The high resolution camera and lens are used in measurement of micro mechanical part, but the region of measurement is very small. It is necessary the re-positioning to measure several regions in one part. The system described in this paper has the accuracy with about $0.9\mu\textrm{m}$ resolution per one pixel and can be applied to measure micro mechanical part.

• 한국공작기계학회:학술대회논문집
• /
• 한국공작기계학회 2002년도 춘계학술대회 논문집
• /
• pp.422-428
• /
• 2002

In this study, actuator, sensor, guide, power transmission element and control method are considered for ultra-precision positioning apparatus. Through previous process, single plane X-Y stage with ultra-precision positioning is manufactured. Global stage for the purpose of materialization with robust system, is combined by using AC servo motor and ball screw and rolling guide. And ultra-precision positioning system is developed by micro stage with elastic hinge type and piezo element. global servo and micro servo for the purpose of materialization positioning accuracy with nm(nanometer) are controlled simultaneously by using incremental encoder and laser interferometer as displacement measurement sensor. Through previous process, ultra-precision positioning system (100mm stroke and ${\pm}$ 10nm positioning accuracy) with single plane X-Y stage are materialized.

• 한국공작기계학회논문집
• /
• 제11권5호
• /
• pp.65-72
• /
• 2002

In this study, actuator, sensor, guide, power transmission element and control method are considered for ultra-precision positioning apparatus. Through previous process, single plane X-Y stage with ultra-precision positioning is manufactured. Global stage for the purpose of materialization with robust system, is combined by using AC servo motor and ball screw and rolling guide. And ultra-precision positioning system is developed by micro stage with elastic hinge type and piezo element. global servo and micro servo for the purpose of materialization positioning accuracy with nm(nanometer) are controlled simultaneously by using incremental encoder and laser interferometer as displacement measurement sensor. Through previous process, ultra-precision positioning system(100mm stroke and $\pm$ l0nm positioning accuracy) with single plane X-Y stage are materialized.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2000년도 춘계학술대회 논문집
• /
• pp.668-671
• /
• 2000

An aerostatic stage has frictionless behavior, so it has a advantage of investigation into driven mechanism such as ballscrew. In this paper, fur investigating positioning characteristic of ballscrew and feedback device in aerostatic stage, we compare the positioning characteristic between full-closed(laser scale) and semi-closed(encoder) system. Experimental results show that the aerostatic stage has a 10nm micro step response and repeatability is improved up to 1.00${\mu}{\textrm}{m}$ using laser scale. We confirm the laser scale compensate error motion of ballscrew, so acquire 1.12${\mu}{\textrm}{m}$ positioning accuracy.

• 벤처창업연구
• /
• 제10권4호
• /
• pp.39-47
• /
• 2015

한국이나 미국 모든 지역에서 창업초기 투자가 활성화되고 이에 힘입은 엔젤투자가 급증하면서 엔젤투자의 투자와 전통적 VC 투자의 사이에 간극이 커지며 Series A Crunch 현상이 심화되고 있다. 따라서 엔젤투자의 투자와 전통적 VC 투자 사이에 존재하는 창업초기 투자펀드 캐즘구간(Series A Crunch)을 보완하며 양자 사이의 가교펀드(Bridge Fund) 역할을 하는 펀드에 대한 필요성이 증가하고 있다. 이에 본 연구는 국내외 Series A Crunch 개념과 현상에 대한 초래원인을 분석하고 이를 극복하는 Micro VC펀드의 도입방안에 대한 정책방안을 제시하였다.

• 한국정밀공학회지
• /
• 제24권1호
• /
• pp.47-56
• /
• 2007

Recently, demands on mechanical micro machining technology have been increased in manufacturing of micro-scale precision shapes and parts. The main purpose of this research is to verify the accuracy and cost efficiency of the mechanical micro machining. In order to measure the precision and feasibility of mechanical micro machining, various micro features were machined. Aluminum molds were machined by a 3-axis micro stage in order to fabricate microchips with $200{\mu}m$ wide channel for capillary electrophoresis, then the same geometry of microchip was made by injection molding. To evaluate the cost efficiency of various micro manufacturing processes, cost estimation for mechanical micro machining was conducted, and actual costs of microchips fabricated by mechanical micro machining, injection molding, and MEMS (Micro electro mechanical system) were compared.

• 한국경제지리학회지
• /
• 제23권1호
• /
• pp.35-55
• /
• 2020

소공인클러스터의 지원정책은 소공인클러스터의 지역적 특성을 반영해야 하지만, 유관기업의 통상적인 정보 수집을 기반으로 비슷한 정책만 내놓고 있다. 소공인클러스터의 지역적 특성이 파악이 안 되므로 지원정책에 반영이 되지 않고 있는 실정이다. 이에 본 연구는 소공인클러스터의 특성을 클러스터의 특징인 국지화, 네트워킹/착근성, 혁신시너지/집단학습의 형성요소로 분석하였으며, 분석된 형성요소를 기반으로 발달단계를 적용해 보았다. 같은 업종이어도 지역적 특성이 다를 수 있으므로, 서울시 의류봉제업의 대표적인 클러스터인 창신지역과 장위지역의 소공인클러스터를 지역적 특성과 발달단계로 비교 연구하였다. 의류봉제 소공인클러스터의 특성 분석 결과, 국지화에서 동종업체 집적은 창신지역이 장위지역보다 높게 나타났으며, 네트워킹/착근성에서 두 지역 모두 잘 형성되어 있었다. 하지만 혁신시너지/집단학습의 협업에서 창신지역은 디자이너 중심으로 장위지역은 소공인 중심으로 이루어져 있고, 박람회 및 세미나 참여와 샘플 및 제작에 있어 창신지역은 적극적인 반면 장위지역은 소극적으로 나타났다. 두 형성요소로 살펴본 결과, 두 지역의 소공인클러스터의 발달단계는 창신 의류봉제 소공인클러스터의 경우 산업지구를 넘어 혁신지구로 진행되고 있고, 장위 의류봉제 소공인클러스터는 산업지구에 머물러 있는 것으로 분석된다. 창신과 장위 의류봉제 소공인클러스터는 지속적인 성장을 위해서는 두 지역의 특성과 발달단계를 반영한 정부의 지원정책이 필요하다고 제언한다.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2006년도 추계학술대회 논문집
• /
• pp.543-544
• /
• 2006