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퍼지논리를 이용한 수평 머시닝 센터의 열변형 오차 모델링
이재하,이진현,양승한,Lee, Jae-Ha,Lee, Jin-Hyeon,Yang, Seung-Han 대한기계학회 2000 大韓機械學會論文集A Vol.24 No.10
As current manufacturing processes require high spindle speed and precise machining, increasing accuracy by reducing volumetric errors of the machine itself, particularly thermal errors, is very important. Thermal errors can be estimated by many empirical models, for example, an FEM model, a neural network model, a linear regression model, an engineering judgment model, etc. This paper discusses to make a modeling of thermal errors efficiently through backward elimination and fuzzy logic strategy. The model of a thermal error using fuzzy logic strategy overcomes limitation of accuracy in the linear regression model or the engineering judgment model. It shows that the fuzzy model has more better performance than linear regression model, though it has less number of thermal variables than the other. The fuzzy model does not need to have complex procedure such like multi-regression and to know the characteristics of the plant, and the parameters of the model can be mathematically calculated. Also, the fuzzy model can be applied to any machine, but it delivers greater accuracy and robustness.
이재하(Jae Ha Lee),박소영(So Young Park) 한국지역지리학회 1996 한국지역지리학회지 Vol.2 No.2
본 논문은 최근에 대도시에 출현한 새로운 정기시장인 도시 요일장의 형성원인, 시장이용자(상인과 소비자)의 속성과 이용행태, 그리고 시장의 기능 등을 밝히기 위하여, 대구시에 개설되고 있는 4곳의 요일장(성서월요장, 칠곡수요장, 시지목요장, 칠곡금요장)을 대상으로 양적이고 질적인 분석을 하였다. 대구의 도시 요일장은 칠곡농협의 금요장에서 본래 기원하였으나, 그것이 본격적으로 형성되고 다른 장소로 확산·발전된 것은 생계를 목적으로 소자본으로 장사하려는 상인(이동상인)들이 종합시장이 없는 신개발 아파트 주거지역에 요즘의 생활리듬(1주일 주기)에 맞는 정기시장을 개설하려고 노력하였기 때문인 것으로 해석된다. 요일장을 이용하는 상인과 소비자의 계속성과 이용행태를 분석·논의하고, 이를 기초로 요일장의 시장기능을 파악해 본 결과, 요일장은 수직적 교환기능이 강하고, 상업기회와 영세민에게 생계유지기능을 제공하며, 농민의 소득증대에 기여하고 있을 뿐만 아니라, 인근주민(소비자)들에게 종합식품 시장으로서 중요한 기능도 수행하고 있는 것으로 밝혀졌다. The purpose of this study is to identify the existence, personal characteristics and behavior of market-participants, and function of urban weekly markets in Taegu City through observation, interview and questionnaire survey. There are four weekly periodic markets such as Seongso(Monday). Chilgok(Wednesday), Siji(Thursday), and Chilgok(Friday) which have recently developed near the new apartment areas on the outskirts of Taegu. The major findings of this study can be summarized as follows: These markets originated from the agricultural cooperative`s Friday markets, but were substantially established by mobile traders or merchants for the sake of their livelihood. Therefore, the existence of these markets is not explained by Stine`s central place perspective but partially explained by Hay`s economic locational and Bromley`s socio-cultural perspective. Most traders are male, aged 30 to 40 years and have an educational level higher than high school. Most of them are living in Taegu and itinerantly visit more than two markets among the four markets by small truck. And most of them sell agricultural products and other food materials. except some who sell manufactured goods. Most consumers are housewives, aged 20 to 30 years and have an educational level higher than high school. Most of them are living within 1,000m and go there on foot. Most of them visit the markets around 3 to 5 p.m. on every market day. And they mostly buy vegetables, fruits, and fishes. Weekly markets provide employment opportunities for those who want to be merchants, and also contribute to the increase of farmers` income, because some traders(18.8%) are farmers who periodically visit markets to sell agricultural products. On the other hand, they function as a general food materials markets to neighboring residents. From these facts, both traders and consumers want weekly markets sustained. Therefore, these markets need to be protected by institutional assistance in spite of being informal markets.
마이크로/나노 핸들링을 위한 마이크로 로보틱 플랫폼 : 비전 기반 3자유도 절대위치센서 개발
이재하(Jae-Ha Lee),Jean Marc Breguet,Reymond Clavel,양승한(Seung-Han Yang) Korean Society for Precision Engineering 2010 한국정밀공학회지 Vol.27 No.1
A versatile micro-robotic platform for micro/nano scale assembly has been demanded in a variety of application areas such as micro-biology and nanotechnology. In the near future, a flexible and compact platform could be effectively used in a scanning electron microscope chamber. We are developing a platform that consists of miniature mobile robots and a compact positioning stage with multi degree-of-freedom. This paper presents the design and the implementation of a lowcost and compact multi degree of freedom position sensor that is capable of measuring absolute translational and rotational displacement. The proposed sensor is implemented by using a CMOS type image sensor and a target with specific hole patterns. Experimental design based on statistics was applied to finding optimal design of the target. Efficient algorithms for image processing and absolute position decoding are discussed. Simple calibration to eliminate the influence of inaccuracy of the fabricated target on the measuring performance also presented. The developed sensor was characterized by using a laser interferometer. It can be concluded that the sensor system has submicron resolution and accuracy of ±4μm over full travel range. The proposed vision-based sensor is cost-effective and used as a compact feedback device for implementation of a micro robotic platform.
이재하 ( Jae Ha Lee ),문명렬 ( Myeong Yeol Moon ) 한국경제지리학회 2002 한국경제지리학회지 Vol.5 No.1
This study examines the spatial diffusion and locational characteristics of convenience stores in Daegu which had increased rapidly in the 1990s. The first convenience store (CVS) was introduced in the zone of transition (Namgu district) adjacent to the city center or CBD in 1992. Thereafter they diffused into CBD and residential areas, but they have centered around places where their steady purchasing population was distributed. As a result, the spatial distribution of CVSs in Daegu shows a very uneven pattern concentrated in areas with many high school, in commercial and business areas, and apartment residential areas. It seems that this pattern is derived from two basic locational factors. Primarily, the location of CVSs in Daegu is very closely related with the spatial distribution of the demand population which will be clients for CVSs. Secondly, it is also affected by the accessibility of streets which the demand population utilizes easily.
이재하(Jae-Ha Lee),오형술(Hyung-Sool Oh) 한국산업경영시스템학회 2021 한국산업경영시스템학회지 Vol.44 No.4
This study focuses on the necessity of MOT methods in companies, especially the utilization level. Based on the analysis structure of the previous study (2012), this study was conducted to compare the results with the previous results. We investigated the settlement level of MOT, the degree of necessity for MOT methods, the degree of actual use, and the Product Realization Process (PRP) for MOT-related researchers in electronic companies (n=184). It was confirmed that the higher the demand for MOT methods in the corporate field, the higher the utilization level (ratio). In particular, the need for and utilization of techniques such as Environmental Analysis, Business Opportunity Analysis, Project Feasibility Review, Roadmap, Risk Management was high. These methods were beneficial along with cost management and quality management techniques. The most challenging part of using MOT methods was the lack of systematic use, the absence of experts, and the difficulty in selecting suitable techniques. The necessity of opening subjects such as Creative Thinking, Communication, Teamwork, and Professional Ethics was high among the PRP subjects. Furthermore, the necessity of opening courses in Cost and Safety Design and Applied Statistics was higher than in the previous study.