• 제목/요약/키워드: Tool run-out

검색결과 50건 처리시간 0.026초

고속 주축에서 클램핑력 및 회전수 변화에 따른 주축 인터페이스 접촉률 변화에 관한 연구 (1) (A Study on the Contact Interval in the Main Spindle Interface of High Speed Spindle according to Variation of Clamping Force and Rotational Speed (1))

  • 황영국;정원지;이춘만
    • 한국정밀공학회지
    • /
    • 제23권3호
    • /
    • pp.147-155
    • /
    • 2006
  • High speed machining has become the main issue of metal rutting. Due to increase of the rotational speed of the spindle, problems, such as the run-out errors, reduced stiffness, must be overcome to improve the machining accuracy. In order to solve the problems, it is important to determine the appropriate clamping unit and tooling system. This paper presents an investigation into an evolution of contact interval which is the interface between spindle taper hole and tool holder shank of the spindle. Finite element analysis is performed by using a commercial code ANSYS according to variation of clamping forces and rotational speeds. This paper proposed fit tolerance in order to evaluate the effects of clamping force and rotational speed on the contact interval in the spindle interface. From the finite element results, it has been shown that the rotational speed rather than clamping force mostly influence on the variation of the contact interval.

An empirical investigation of nuclear energy consumption and carbon dioxide (CO2) emission in India: Bridging IPAT and EKC hypotheses

  • Danish, Danish;Ozcan, Burcu;Ulucak, Recep
    • Nuclear Engineering and Technology
    • /
    • 제53권6호
    • /
    • pp.2056-2065
    • /
    • 2021
  • The transition toward clean energy is an issue of great importance with growing debate in climate change mitigation. The complex nature of nuclear energy-CO2 emissions nexus makes it difficult to predict whether or not nuclear acts as a clean energy source. Hence, we examined the relationship between nuclear energy consumption and CO2 emissions in the context of the IPAT and Environmental Kuznets Curve (EKC) framework. Dynamic Auto-regressive Distributive Lag (DARDL), a newly modified econometric tool, is employed for estimation of long- and short-run dynamics by using yearly data spanning from 1971 to 2018. The empirical findings of the study revealed an instantaneous increase in nuclear energy reduces environmental pollution, which highlights that more nuclear energy power in the Indian energy system would be beneficial for climate change mitigation. The results further demonstrate that the overarching effect of population density in the IPAT equation stimulates carbon emissions. Finally, nuclear energy and population density contribute to form the EKC curve. To achieving a cleaner environment, results point out governmental policies toward the transition of nuclear energy that favours environmental sustainability.

A Study on Hydrodynamic Stiffness Characteristics of Air Bearing for High Speed Spindle

  • Lee, J.Y.;Lee, D.W.;Seong, S.H.;Lee, Y.C.
    • 한국윤활학회:학술대회논문집
    • /
    • 한국윤활학회 2002년도 proceedings of the second asia international conference on tribology
    • /
    • pp.115-116
    • /
    • 2002
  • This study was carried out as one of efforts to overcome difficulties in air bearing design due to low stiffness and low damping. Hydrodynamic effects on hydrodynamic stiffness of a fluid film in a high speed air bearing with tow-row air sources are investigated. The hydrodynamic effects by the high speed over DN 1,000,000 and eccentricity of a proceeding which are not considered in conventional design of an air bearing need to be reconsidered. The hydrodynamic effects, which dominantly influence on the load capacity of air bearing, are caused mainly by proceeding speed, eccentricity, and the source positions. The two-row source arrangement in the air bearing produces quite unique hydrodynamic effects with respect to pressure distribution of the air film. Optimal arrangement of the two-row sources improves performance of an air bearing in film reaction force and loading capacity of high speed spindles. This study compares the pressure distribution by numerical simulation as a function of eccentricity of proceeding and the source positions. The air source position 1/7L form one end of an air bearing was found to be superior to source position of 1/4L. The dynamic stiffness were obtained using a two-dimensional cutting method which can directly measure the cutting reaction forces and the displacements of the spindle in two directions using a tool dynamometer and transducer sensors. Heat generation in the air film can not be negligible over the speed of DN 2,000,000. In order to analysis effects of heat generation on the characteristics of air bearing, high cooling bearing spindle and low cooling bearing spindle were tested and compared. Characteristics of the frequency response of shaft and motion of run out errors were different for the spindle. The test results show that, in the case of low cooling bearing spindle, the stiffness became smaller due to heat generation. The results, which were obtained for high speed region, may be used as a design information for spindle which can be applied to precision devices such as ultra precision grinding and ultra high speed milling.

  • PDF

Determinants of Shopping Experience for Mall Shoppers: Empirical Investigation in an Emerging City of Raipur (India)

  • Singh, Harvinder;Prashar, Sanjeev;Agarwal, Rashmi;Sharma, Tarun Kumar
    • 아태비즈니스연구
    • /
    • 제5권1호
    • /
    • pp.13-21
    • /
    • 2014
  • Shopping malls have become key players in the Indian retail space. Even in upcoming Indian towns, malls have been mushrooming. Raipur, the capital city of the Indian state of Chhattisgarh has witnessed the growth over the last few years. However, this unplanned growth of malls in cities is expected to lead to oversupply of mall space in the near future, making things difficult for mall developers. The study is an attempt to identify appropriate strategies for mall developers to iron out such kinks. This paper presents 'shopping experience' as a tool to compete, succeed and explore its composition in terms of its constituent factors. The paper uses Exploratory Factor Analysis (EFA) on a non-probability sample of 350 respondents. It condenses a set of twenty-two mall variables into five factors that directly influence the shopping experience. These factors included ambience, infrastructure, marketing focus, convenience and safety and security. In terms of significance, shoppers assigned different weightage to each of these factors. The study shed light on interesting insights regarding the expectations of mall shoppers in the city of Raipur. The results though interesting, may be extended to different social, economic and geographic contexts to check the universality. While strategizing, mall developers must assign proportionate effort on the factors based on the respective contribution to shopping experience. In light of intensifying competition in Raipur, the study is significant for future prospects of malls. In the absence of a scientific and objective basis, the developers run risk of making wrong investment and management decisions. This paper is a useful addition to the body of knowledge on management of shopping malls in India and is unique in terms of its focus on mall shoppers in the smaller Indian cities like Raipur.

  • PDF

Beach Cusp 생성기작으로 기능하는 Synchronous Edge Wave 수치해석 (Numerical Analysis of Synchronous Edge Wave Known as the Driving Mechanism of Beach Cusp)

  • 이형재;조용준
    • 한국해안·해양공학회논문집
    • /
    • 제31권6호
    • /
    • pp.409-422
    • /
    • 2019
  • Beach cusp의 생성기작으로 기능하는 Synchronous Edge wave의 수리특성을 살펴보기 위한 3D 수치모의를 OpenFOAM 기반 tool box인 IHFOAM을 활용하여 수행하였다. 파랑모형은 RANS[Reynolds Averaged Navier-Stokes equation]와 연속방정식으로 구성하였으며, Synchronous Edge wave 형성에 필요한 연안방향으로 파고가 변조되는 short-crested waves는 동일한 주기와 파고를 지니는 두 개의 Cnoidal wave가 전면 해역에서 비스듬히 조우되도록 조파하여 재현하였다. 모의결과 파랑 집중단면에서의 유속이 파랑 분산단면보다 전체적으로 크게 모의되었다. 또한 파랑 집중단면의 경우 해안방향 흐름[up-rush]이 먼 바다방향 흐름[back-wash]보다 세기는 우월하나 지속기간은 짧은 비선형 파동계의 일반적인 성정을 지니는 것으로 모의되었다. 이와 더불어 처오름 정점에서 양쪽의 분산단면으로 흐름이 나뉘며 약해지는 b ack-wash로 인해 up-rush 최대유속은 back-wash 최대유속의 두 배 가까이 증가하는 것으로 관측되었다. 이에 비해 파랑 분산단면의 경우 집수효과로 해안 인근 수역에서는 먼 바다방향 흐름이 해안방향흐름보다 우월하게 모의되었다. 또한 천수 중간 수역에서는 해안방향 흐름이 여전히 우세하나 비대칭 정도는 현저하게 감소하였다. 이러한 수리특성은 Synchronous Edge wave의 전형적인 성정으로 수치모의가 성공적으로 이루어진 것으로 판단된다. 이 과정에서 너울이 우월한 해양환경에서 해빈이 느리지만 점진적으로 복원되는 과정에서 주 기작으로 기능하는 경계층 streaming에 대한 새로운 해석도 제시되었다.

가정간호사업 운용을 위한 정보전달체계 개발 I (가정간호 데이터베이스 구축과 뇌졸중 환자의 가정간호 전산개발) (Development of the Information Delivery System for the Home Nursing Service)

  • 박정호;김매자;홍경자;한경자;박성애;윤순녕;이인숙;조현;방경숙
    • 가정간호학회지
    • /
    • 제4권
    • /
    • pp.5-22
    • /
    • 1997
  • The purpose of the study was to development an information delivery system for the home nursing service, to demonstrate and to evaluate the efficiency of it. The period of research conduct was from September 1996 to August 31, 1997. At the 1st stage to achieve the purpose, Firstly Assessment tool for the patients with cerebral vascular disease who have the first priority of HNS among the patients with various health problems at home was developed through literature review. Secondly, after identification of patient nursing problem by the home care nurse with the assessment tool, the patient's classification system developed by Park (1988) that was 128 nursing activities under 6 categories was used to identify the home care nurse's activities of the patient with CAV at home. The research team had several workshops with 5 clinical nurse experts to refine it. At last 110 nursing activities under 11 categories for the patients with CVA were derived. At the second stage, algorithms were developed to connect 110 nursing activities with the patient nursing problems identified by assessment tool. The computerizing process of the algorithms is as follows: These algorithms are realized with the computer program by use of the software engineering technique. The development is made by the prototyping method, which is the requirement analysis of the software specifications. The basic features of the usability, compatibility, adaptability and maintainability are taken into consideration. Particular emphasis is given to the efficient construction of the database. To enhance the database efficiency and to establish the structural cohesion, the data field is categorized with the weight of relevance to the particular disease. This approach permits the easy adaptability when numerous diseases are applied in the future. In paralleled with this, the expandability and maintainability is stressed through out the program development, which leads to the modular concept. However since the disease to be applied is increased in number as the project progress and since they are interrelated and coupled each other, the expand ability as well as maintainability should be considered with a big priority. Furthermore, since the system is to be synthesized with other medical systems in the future, these properties are very important. The prototype developed in this project is to be evaluated through the stage of system testing. There are various evaluation metrics such as cohesion, coupling and adaptability so on. But unfortunately, direct measurement of these metrics are very difficult, and accordingly, analytical and quantitative evaluations are almost impossible. Therefore, instead of the analytical evaluation, the experimental evaluation is to be applied through the test run by various users. This system testing will provide the viewpoint analysis of the user's level, and the detail and additional requirement specifications arising from user's real situation will be feedback into the system modeling. Also. the degree of freedom of the input and output will be improved, and the hardware limitation will be investigated. Upon the refining, the prototype system will be used as a design template. and will be used to develop the more extensive system. In detail. the relevant modules will be developed for the various diseases, and the module will be integrated by the macroscopic design process focusing on the inter modularity, generality of the database. and compatibility with other systems. The Home care Evaluation System is comprised of three main modules of : (1) General information on a patient, (2) General health status of a patient, and (3) Cerebrovascular disease patient. The general health status module has five sub modules of physical measurement, vitality, nursing, pharmaceutical description and emotional/cognition ability. The CVA patient module is divided into ten sub modules such as subjective sense, consciousness, memory and language pattern so on. The typical sub modules are described in appendix 3.

  • PDF

산림유역의 토양유실량(土壤流失量) 예측을 위한 지리정보(地理情報)시스템의 범용토양유실식(汎用土壤流失式)(USLE)에의 적용 (Application of GIS to the Universal Soil Loss Equation for Quantifying Rainfall Erosion in Forest Watersheds)

  • 이규성
    • 한국산림과학회지
    • /
    • 제83권3호
    • /
    • pp.322-330
    • /
    • 1994
  • 토양침식에 영향을 미치는 강우, 토양, 지형, 식생 등을 종합적으로 고려하여 단위면적당 토양유실량(土壤流失量)을 예측하는 범용토양유실식(汎用土壤流失式)(Universal Soil Loss Equation)을 지리정보(地理情報)시스템(GIS)에 접목시켰다. 경기도 광릉 임업연구원 시험림을 연구지역으로 선정하여 이곳에서 지난 12년 동안 측정된 시간별 강우자료를 이용하여 강우인자(强雨因子)(R) 값을 산출하였고, 토양도, 지형도, 위성자료 등을 이용하여 USLE 계산에 필요한 다른 인자들의 값을 $25{\times}25m^2$의 격자마다 입력하여 디지털공간정보 데이터베이스를 구축하였다. 각 격자단위로 USLE에 의하여 토양유실량이 계산된 후 그 결과를 종합하여 토양유실의 정도를 공간적으로 살펴볼 수 있는 디지털지도가 산출되었다. GIS에 의한 USLE의 적용은 일정한 테두리 안의 산림유역(山林流域)에서 발생되는 강우에 의한 토양유실량을 추정할 수 있을 뿐만아니라, 주변지역과 비교하여 토양유실의 위험이 높은 특정지점을 공간적으로 파악할 수 있다는 장점이 있다. 이러한 접근 방법은 임지전용(林地轉用), 임도(林道)개설, 벌채, 산불 및 병충해에 의한 임지의 변화가 토양침식에 미치는 영향을 효과적으로 분석할 수 있는 도구로 사용될 수 있을 것이다.

  • PDF

토양유실을 고려한 양서파충류의 서식지 관리지역 선정방법 (A Methodology for Selection of Habitat Management Areas for Amphibians and Reptiles Considering Soil Loss)

  • 김지연;이동근;모용원
    • 한국환경복원기술학회지
    • /
    • 제21권6호
    • /
    • pp.55-69
    • /
    • 2018
  • As disaster risk and climate change volatility increase, there are more efforts to adapt to disasters such as forest fires, floods, and landslides. Most of the research, however, is about influence of human activities on disaster and there is few research on disaster adaptation for species. Previous studies focusing on biodiversity in selecting conservation areas have not addressed threats of disaster in the habitats for species. The natural disasters sometimes play role of drivers of ecological successions in the long run, but they might cause serious problems for the conservation of vulnerable species which are endangered. The purpose of this study is to determine whether soil loss (SL) is effective in selecting habitat management areas for amphibians and reptiles. RUSLE model was used to calculate soil loss (SL) and the distribution of each species (SD) was computed with MaxEnt model to find out the biodiversity index. In order to select the habitat management area, we estimated the different results depending if value of soil loss was applied or not by using MARXAN, a conservation priority selection tool. With using MARXAN, conservation goals can be achieved according to the scenario objectives, and the study has been made to meet the minimum habitat area. Finally, the results are expressed in two; 1) the result of soil loss and biodiversity with MATRIX method and 2) the result of regional difference calculated with MARXAN conservation prioritization considering soil loss. The first result indicates that the area with high soil loss and low species diversity have lower conservation values and thus can be managed as natural disturbances. In the area where soil loss is high and species diversity is also high, it becomes where a disaster mitigation action should be taken for the species. According to the conservation priorities of the second result, higher effectiveness of conservation was obtained with fewer area when it considered SL in addition to SD, compared to when considered only biodiversity. When the SL was not taken into consideration, forest area with high distribution of species were important, but when SL considered, the agricultural area or downstream of the river were represented to be a major part of habitats. If more species data or disaster parameters other than soil loss are added as variables later, it could contribute as a reference material for decision-making to achieve various purposes.

노동시장정책의 확대는 복지국가 재정위기 해소에 유효한가? - 소극적·적극적 노동시장정책의 상호작용 효과 (Is Increasing of Labor Market Policy Expenditure Effective Policy Tool to Lessen the Fiscal Crisis in Welfare State? : The Interaction between Active and Passive Labor Market Policy)

  • 배은총;고혜진;조효진
    • 한국사회정책
    • /
    • 제24권4호
    • /
    • pp.185-222
    • /
    • 2017
  • 본 연구는 복지국가의 재정건전성 담보에 노동시장정책 확충이 기여하는지를 실증적으로 규명하는 연구이다. 구체적인 분석은 20개 OECD 국가들의 1985년부터 2015년까지의 자료를 토대로 결합시계열 회귀분석과 Baron과 Kenny(1986)의 단계적 매개효과 검증을 통해 이루어졌으며, 분석의 강건성 확인을 위해 시스템 동적패널분석을 추가 수행하였다. 분석모형을 설정함에 있어 본 연구에서는 기존 연구에서 간과되어온 두 측면, 노동시장정책 성과들 간의 선후 관계와 노동시장정책의 상호작용 효과를 반영하였다. 분석결과 노동시장정책은 복지국가의 부채 수준에 유의미한 영향을 미친다. 이때, 적극적 노동시장정책은 고용률을 매개하여 국가 부채 수준을 효과적으로 낮추는 것으로 나타난다. 반면에, 소극적 노동시장정책은 고용률 제고 기능을 하지 못하는 것은 물론 단기적으로는 국가 부채 부담을 늘리는 경향도 있다. 다만, 이것의 영향은 적극적 노동시장정책과 결부되면 부적 영향이 상쇄되는 것으로 나타난다. 즉, 단기적으로 노동시장정책 지출 확대로 재정수지가 악화될 수는 있지만, 장기적으로 이는 고용률 제고 효과를 통해 복지국가의 재정건전성을 담보하는 데 효과적인 역할을 수행할 수 있는 것으로 보인다.

큐레이(Q-ray)와 티스캔(T-scan)을 사용한 치아균열증후군(cracked tooth syndrome)과 교합 사이의 상관관계에 대한 분석 (Analysis of relationship between cracked tooth syndrome and occlusion using Q-ray and T-scan)

  • 안도관;최진우;김유성;표세욱;김희경
    • 대한치과보철학회지
    • /
    • 제59권3호
    • /
    • pp.271-280
    • /
    • 2021
  • 목적: 본 연구의 목적은 큐레이(Q-ray)와 티스캔(T-scan)을 사용하여 치아균열증후군(cracked tooth syndrome)과 교합 사이의 상관관계를 평가하는 것이다. 대상 및 방법: 2019년 3월 1일부터 2020년 12월 31일까지 아주대학교병원 치과진료센터 치과보철과에 내원한 환자 중 실험대상 포함기준을 만족하며 치아균열증후군으로 진단된 대구치(실험군)를 1개 이상 가지고 있으나 동일 악궁 반대측에는 정상 치아(대조군)를 가진 환자 51명을 대상으로 하였다. 실험군과 대조군 치아의 사진을 Q-ray pen을 이용해 촬영하여 최대형광소실도(ΔFmax)와 최대적색형광도(ΔRmax)을 측정하였고 T-scan 검사를 통해 실험군과 대조군 치아의 상대적 교합강도 및 편심위운동시 이개시간을 측정하였다. Mann-Whitney U test를 통해 실험군과 대조군 사이의 상대적 교합강도와 이개시간의 차이 및 균열치아의 냉검사와 온검사 결과에 따른 군들 간의 최대형광소실도(ΔFmax)와 최대적색형광도(ΔRmax)의 차이를 통계적으로 분석하였다 (α = .05). Spearman correlation analysis를 이용해 최대형광소실도(ΔFmax)와 최대적색형광도(ΔRmax)와 상대적 교합강도 및 이개시간 간의 상관관계를 분석하였다. 결과: 균열치의 상대적 교합강도 및 이개시간은 정상치아에 비하여 통계적으로 유의하게 컸다 (P < .05). 균열치 중 냉검사와 온검사 결과에 따른 각 군들 간의 최대형광소실도(ΔFmax)와 최대적색형광도(ΔRmax)는 통계적으로 유의미한 차이를 보이지 않았다(P > .05). Spearman correlation analysis 결과, 최대형광소실도(ΔFmax)와 최대적색형광도(ΔRmax)와 상대적 교합강도 및 이개시간 간에는 유의미한 상관관계가 없었다 (P > .05). 결론: 본 연구의 결과에 따르면 상대적 교합강도와 이개시간 등의 교합 요소는 치아균열증후군의 발병과 연관이 있었다. Q-ray 검사를 통한 최대형광소실도(ΔFmax)와 최대적색형광도(ΔRmax)의 측정은 치아균열증후군의 진단에는 임상적으로 유용하게 사용될 수 있지만, 임상증상과 정량적인 관계를 입증하지는 못하였다.