• 한국정밀공학회지
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• 제18권2호
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• pp.126-131
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• 2001

One of the major obstacles in testing or evaluating precisely the thermal behavior of a machine tool is the difficulty in measuring the heat transfer coefficients on the surfaces by a conventional method. This paper presents a new approach based on the inverse method to identify the values of heat transfer coefficients by using temperature changes measured on the surfaces of a machine tool during a short period in its operating. In the present method, a machine tool structure is modeled by the finite element method and the characteristic curves of the temperature change at several points on machine tool surfaces are theoretically derived in the form that they contain the heat transfer coefficient as an unfixed heat source are approximated so that the theoretical characteristic curves of temperature change fit the measured ones as closely as possible.

• 한국정밀공학회지
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• 제24권10호
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• pp.37-45
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• 2007

End-milling is intermittent cutting process performed by a tool with a number of teeth. Its cutting forces are commonly measured by the tool dynamometer which has rectangular coordinates. In this case, the pattern of cutting forces is different according to cutting conditions. At a certain cutting condition, the sign of cutting force changes from positive to negative during a revolution of one tooth. The change of force direction excites a cutting tool and severe vibration arises when radial depth of cut increases. In this study, cutting experiments and simulations were carried out in order to explain the cause of the change of the cutting force direction. In addition, the effect of the cutting force change was discussed in terms of chatter vibration in end milling.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1993년도 추계학술대회 논문집
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• pp.58-63
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• 1993

The charactistics of AE(Acoustic Emission) signal is related to cutting conditions, tool materials and tool geometry in metal cutting. The tool geometry change which is derived from tool wear affects the source of AE signal in machining process. The relationship between AE signal and tool wear was experimentally investigated. THe value of RMS(Root Mean Sequare) and Amplitude of AE signal were increased in tool wear condition. Also the high value of Count per Hit and Count vs. Frequency was observed in this condtion. As a result, tool wear can be effectively detected by AE signal during cutting operation.

• 한국기계가공학회지
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• 제18권6호
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• pp.26-32
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• 2019

Ball end mills used for high-speed and high-precision machining require longer machining time than flat end mills or face cutters, since the tool diameter is limited and the rigidity is reduced by the characteristics of the tool's cutting edge: at the top end of the tool, the cutting speed approaches zero and hardly removes any material. Because there is little material removal at the top end of the ball end mill, the outer cutting edge performs the majority of the work; this irregular cutting force deforms the tool and shortens its life. In this study, we attached an eddy-current sensor to a tool to measure the deformation from the cutting force and we used a tool dynamometer to measure the cutting force. We found that the change in cutting force is dependent on the change in feed rate during square-shaped processing and, as the feed rate is accelerated, the cutting force also increases. Higher cutting forces increase tool deformation.

• 한국지리정보학회지
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• 제19권1호
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• pp.1-11
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• 2016

기후변화는 환경 분야에서 가장 주목받는 화두이며, 인류에게 직면한 가장 도적적인 과제이다. 이러한 문제를 해결하는 방법은 다양하지만, 우리나라의 경우 국가 차원의 1~2차 국가기후변화 적응대책을 수립하고, 각 광역 및 기초 지자체의 기후변화 적응 시행대책 수립을 의무화하고 있다. 기후변화 취약성 평가는 기후변화 적응 시행대책을 수립함에 있어 필수적인 역할을 담당한다. 그러나 취약성 평가는 다양한 영향인자의 복합적 연산을 통해 도출됨으로 개별적인 평가를 수행하기에는 어려움이 있다. 이에 본 연구에서는 기초 및 광역 지자체 차원에서 활용 가능한 웹기반 기후변화 취약성 평가 지원도구(VESTAP)를 개발하였다. VESTAP은 크게 지표 DB와 취약성 평가 및 표출 도구로 구성되어 있다. 지표 DB는 RCP(Representative Concentration Pathways) 4.5와 8.5로 모의된 총 455개의 미래 기후자료, 대기 환경자료, 기타 인문사회통계 자료와 그에 따른 메타데이터 정보를 포함한다. 표출 도구는 각 취약성 평가의 결과에 대한 공간분포, 편향성, 도표화 등 다양한 분석 기능을 제공함으로써 편의성을 극대화 하였다. VESTAP를 활용하여 세종특별자치시에 대한 미세먼지에 의한 건강 취약성 평가를 시범적으로 수행하였으며, 부강면이 상대적으로 취약성이 가장 높은 수치를 나타냈다. 개발된 도구를 활용하여 각 지자체는 보다 쉽고, 편리하게, 그리고 과학적 증거에 기반한 기후변화 적응 시행대책을 수립할 수 있을 것으로 기대한다.

• 공학교육연구
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• 제20권5호
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• pp.43-49
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• 2017

This paper deals with inter-relationship change of women's university students on the process of SW development project using social collaboration tool. Inter-relationship is one of the basic vocational competency in NCS(National Competency Standards) of Korea. We redesigned the curriculum of "Software Engineering" subject for this study and composed the project teams of students to develop software. The details of inter-relationship are satisfaction, communication, faith, friendliness, sensitivity, openness and consideration. From the result of this study, faith, openness and consideration have positive effect but satisfaction, communication, friendliness and sensitivity have no meaningful effect. The surveys were conducted in the beginning of semester and the same surveys were conducted again in the end of semester. The results were verified by paired t-test with SPSS 18.0. It is significant that the using of social collaboration tool for team project has positive effect on inter-relationship change, especially faith of women's university students. This study has some limitations for generalization but has meaning as new trial to enlarge the basic vocational competency of students in major subject, "Software Engineering". We expect new study for inter-relationship change of students to evaluate generality based on the proposed method in this paper.

• 한국기계가공학회지
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• 제20권2호
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• pp.38-44
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• 2021

To cater to the transition from single-color to multicolor/multi-material printing, this paper proposes a cartridge-replacing type multi-nozzle Fused Depositon Modeling(FDM) three-dimensional (3D) printer. In the test printing run, tool change failure/wobble/layer shift occurred. It was confirmed that improper support was the cause of this tool change failure. As a solution, spline and electromagnetic cartridges were designed. Wobble was caused by machine vibration and the motor stepping out. To minimize wobble, an additional Z-axis was installed, and the four-point bed leveling method was used instead of the three-point bed leveling method. The occurrence of layer shift was ascribed to the eccentricity of the Z-axis lead screw. Therefore, slit coupler was replaced with an Oldham type. In addition to the mechanical supplementation, the control environment was integrated to prevent accidents and signal errors due to wire connections. Before the final test printing run, a rectifier circuit was added to the motor to secure precise control stability. The final test printing run confirmed that the wobble/layer shift phenomenon was minimized, and the maximum error between layers was reduced to 0.05.

• Journal of Forest and Environmental Science
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• 제35권1호
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• pp.47-53
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• 2019

This study applies the concept of climate change vulnerability assessment in order to suggest climate change adaptation effects in a quantitative manner, given that previous studies have hitherto rely on qualitative assessment, as climate change adaptive policies are currently being implemented by local governments of Korea. The vulnerability assessment tool used in this study is VESTAP ("Vulnerability assESsment Tool to build a climate change Adaptation Plan"), which was developed by the Korea Adaptation Center for Climate Change (KACCC), and applied to gauge the vulnerability of pine trees to diseases and pests within Chungcheongnam-do. The climate change adaptation project for vulnerability improvement was assessed only in terms of forest disaster prevention and change in regional climate change vulnerabilities within 16 regions of Chungcheongnam-do as the result of 2016 Climate Change Adaptation Project (Forest Disaster Prevention Project). As a result, it was observed that climate change adaptive capacity has improved according to change in the area of forestland with disaster prevention, and the vulnerability indicator decreased, confirming the impact of the climate change adaptation (forest disaster prevention) project. Also, analysis of regional climate change adaptation project scales and change in vulnerabilities allowed us to determine the regional propriety of climate change adaptation (forest disaster prevention) projects launched in 2016.

• 한국정밀공학회지
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• 제20권7호
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• pp.147-154
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• 2003

An effective die-polishing robot system is developed. ATC (Automatic Tool Change), tool posture angle control, and robot program for polishing application are developed and integrated into a robotic system that consists of a robot, pneumatic grinding tool, and grinding abrasives (papers and special films). ATC is specifically designed to exchange whole grinding tool set for complete unmanned operation. A tool posture angle control system is developed for the tools to maintain a specified skew angle rather than right angle on the surface for best finishing results. A PC and the robot controller control ATC and tool posture angle. Also, there have been more considerations on enhancing the performance of the system. Elastic material is inserted between the grinding pad and the holder for better grinding contact. Robot path data are generated automatically from the NC data of previous machining process.

• 인터넷정보학회논문지
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• 제5권4호
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• pp.11-22
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• 2004

프로젝트를 수행함에 있어서 프로세스의 지속적인 개선 및 개선된 프로세스, 생산되는 산출물, 태스크들의 변경을 모든 사용자에게 통지하고 관리하는 작업은 필수적이다. 기존의 프로젝트 관리 도구는 프로젝트 활동의 정의 및 변경을 지원하고, 형상관리 도구는 버전제어, 작업공간 관리, 빌드 관리 등을 지원한다. 프로세스와 산출물을 관리하기 위해서 서로 다른 두개의 도구를 사용하는 것은 각각의 도구를 구매하는데 많은 비용이 들 뿐만 아니라 다양한 도구의 사용법을 익혀야 하는 번거로움이 있다. 따라서 된 논문에서는 웹을 기반으로 프로세스 및 산출물 관리 기능 통합, 인터페이스 통합, 자료 통합 도구의 모델을 제안하였다. 제안한 도구는 ebXML을 이용하여 컴포넌트 기반 개발 프로세스 모델을 정의하고. 프로세스의 진행 상태 기록, 변경 요청에 따른 처리, 태스크별 작업 진행 보고서 작성, 산출물 등록과 변경, 버전 기록, 산출물 또는 서식 검색 등의 기능을 수행하도록 하였다. 또한 제안한 통합관리 도구를 사용함으로써 소프트웨어 공학 활동에 참여하는 시스템 관련 자들이 분산 개발 환경에서 프로세스 수행에 필요한 정보와 산출물 관리에 요구되는 정보를 공유하여 관리의 체계화 및 표준화를 얻도록 하였다.