절삭력과 음향방출 신호를 이용한 밀링공구의 파손 검출

맹민재,Maeng, Min-Jae 한국기계가공학회 2004 한국기계가공학회지 Vol.3 No.1

An on-line monitoring system of endmill failure such as weal, chipping, and fracture is developed using AE, cutting force Characteristic variations of AE and cutting force signals due to endmill failure are identified as follows. When endmill fracture occurs, AE count rate shows a rapid Increase in conjunction with a subsequent decrease while a standard deviation of the principal cutting force Increases significantly. The increase of AE count rate precedes the Increase of standard deviation of principal cutting force. Chipping results in relatively small increase and decrease of AE count rate without any significant variation of the cutting force Gradual increase of AE count rate and mean principal cutting force are Identified to be related with the wear of cutter. A cutter fracture detection algorithm is developed based on the present results. The signals me normalized to enhance the applicability of the algorithm to Wide those of fresh cutters, and qualitative characteristics of AE signals encountered at the moment of fracture are employed. It is demonstrated that the algorithm can detect the cutter fracture successfully.

선삭가공에서 공구마멸에 따른 절삭력과 AE 신호의 특성 연구

맹민재(Min Jae Maeng),정준기(Joon Ki Chung) 한국공작기계학회 1995 한국공작기계학회지 Vol.4 No.2

헬릭스각이 버형성에 미치는 영향

맹민재(Min-Jae Maeng),정준기(Joon-Ki Chung) 한국공작기계학회 2000 한국공작기계학회지 Vol.9 No.4

실험계획법을 이용한 로타리 공구의 절삭 특성

맹민재 ( Min-jae Maeng ) 한국고등직업교육학회 2011 한국고등직업교육학회논문집 Vol.12 No.2

Continuous research and development activities in the field of metal cutting have led to the evolution of a number of new manufacture processes. One such interesting development is the use of rotary tools in machining. These tools use continuous indexing of cutting edge actuated by either cutting velocity vector or an external power. This paper deals with the study of feasibility of rotary carbide tools in the machining of aluminium alloy(2024-T4). A rotary tool holder was designed and manufactured for this work. Experiments were performed using design of experiment to analyse the influence of various factors and their interactions on the cutting characteristics of rotary carbide tools during machining.

고속가공을 위한 정면밀링커터 바디시스템 개발

장성민(Sung-Min Jang),맹민재(Min-Jae Maeng),조명우(Myeong-Woo Cho) Korean Society for Precision Engineering 2004 한국정밀공학회지 Vol.21 No.12

In modern manufacturing industries such as the airplane and automobile, aluminum alloys which are remarkable in durability have been utilized effectively. High-speed machining technology for surface roughness quality of workpiece has been applied in these fields. Higher cutting speed and feedrates lead to a reduction of machining time and increase of surface quality. Furthermore, the reduction of time required for polishing or lapping of machined surfaces improves the production rate. Traditional milling process for high speed cutting can be machined with end mill tool. However, such processes are generally cost-expensive and have low material removal rate. Thus, in this paper, face milling cutter which gives high MRR has developed face milling cutter body for the high speed machining of light alloy to overcome the problems. Also vibration experiment to detect natural frequency in free state and frequency characteristics during machining are performed to escape resonance.

전문대학 공학계열 수업에서의 성찰저널 적용 사례연구

홍유나(Yuna Hong),맹민재(Min-Jae Maeng),정애경(Ae Kyung Chung),이상회(Sang-Hoi Yi),김능연(Neung-Yeun Kim) 大韓電子工學會 2010 電子工學會論文誌 IE (Industry electronics) Vol.47 No.1

본 연구의 목적은 전문대학 공학계열 학생들의 학업성취와 자기조절학습전략의 향상을 위하여 성찰저널을 수업에 적용하고 그 효과성을 검증하는 데 있다. 본 연구에서 사용한 성찰저널은 학생들의 학업성취와 자기조절학습전략, 특히 메타인지와 비판적 사고 등을 향상시키기 위한 인지도구로서 (1) 5점 Likert 척도로 된 자기평가, (2) 수업에세이, (3) 동료와의 대화, (4) 교수님과의 대화 등으로 구성되어 있는 '구조화된 성찰저널'이다. 이러한 성찰저널의 효과를 검증하기 위하여 2009년 8월 24일부터 10월 16일까지 총 8주 동안 공학계열 1학년 94명(이론반 42명, 실험실습반 52명)을 연구반(성찰저널 적용 수업)과 비교반(성찰저널을 적용하지 않는 반)으로 구분하여 수업을 진행하고, 이러한 수업 유형에 따라 사전과 사후의 학업성취도와 자기조절학 습전략의 차이가 있는지를 검증하기 위해 공분산 분석(analysis of covariance)을 실시하였다. 연구 결과, 성찰저널이 공학계열 신입생들의 학업성취도와 자기조절학습전략을 향상시키는 데 긍정적인 효과가 있음이 증명되었다. The main purpose of this study was to develope a reflective journal and examine its effects on student's academic achievement and self-regulated learning strategies. For this study, 'a structured reflective journal' was designed through the steps of systems approach with the purpose of enhancing student's academic achievement and self-regulated learning strategies, especially meta-cognition and critical thinking. The reflective journal used in this study contained the constructive elements of (1) self-evaluation with 5 likert scale, (2) learning essay, (3) dialogue with peers, and (4) dialogue with professor. A total of 94 freshmen enrolled in one of two sections of the engineering courses(theory-based class and experiment and practice-based class) participated in the study for 8 weeks. A pre-test-post-test design was used to examine the effects of the application of reflective journal on student's achievement and self-regulated learning strategies. For the result, analysis of covariance was conducted to determine whether there were any academic achievement differences and self-regulated learning strategy differences. The results suggested that students were taking advantages of the reflective journal, and there were statistically significant differences in academic achievement in the experiment and practice-based class and self-regulated learning strategies in both classes.

전문대학 공학계열 신입생들의 메타인지, 문제해결력 및 학습몰입이 성취도에 미치는 영향

정애경(Ae Kyung Chung),맹민재(Min-Jae Maeng),이상희(Sang-Hoi Yi),김능연(Neung-Yeun Kim) 大韓電子工學會 2010 電子工學會論文誌 IE (Industry electronics) Vol.47 No.2

본 연구는 전문대학 공학계열 신입생들을 대상으로 메타인지, 문제해결력, 몰입과 성취도간의 관계를 규명하는 것을 목적으로 하였다. 본 연구를 위하여 메타인지 문제해결력 몰입을 독립변인으로 성취도를 종속변인으로 하는 가설적 모형을 상정한 다음, 2009년 D 대학 공학계열 6개학과 신입생 396명을 대상으로 2009년 2학기 초에 메타인지와 문제해결력을 학기말에 몰입과 성취도(성적)를 측정하였다. 수집한 자료를 대상으로 회귀분석을 실시하여 독립변인이 종속변인에게 미치는 영향력을 검증하였다. 분석결과, 메타인지와 문제해결력이 전문대학 공학계열 신입생들의 성취도에 유의한 영향을 미치는 변인임을 확인하였으며, 몰입은 학생들의 메타인지, 문제해결력 및 성취도간을 매개하는 역할을 하는 것으로 예측되었다. 이러한 연구결과를 바탕으로 전문대학 공학계열 학생들의 수업효과를 높이기 위한 전략과 방법을 수립 시 메타인지와 몰입과 같이 학생들의 문제해결능력에 영향력이 높은 변인들을 우선적으로 고려할 것을 제안하였다. The main purpose of this study was to examine the effects of meta-cognition, learning flow and problem solving ability of the college engineering students on academic achievement. For this purpose, a total of 396 college engineering freshmen of the six different departments was chosen to conduct a survey. A hypothetical model was proposed, which was composed of meta-cognition, problem solving ability and learning flow as the prediction variables, and academic achievement as the outcome variables. The results of this study through multiple regression analysis showed that meta-cognition, learning flow and problem solving ability significantly influenced on the college engineering studnets' academic achievement. In addition, learning flow was used as a significant mediated variable in the relationships among meta-cognition, problem solving ability and academic achievement. Based on these study results, the above variables investigated in this study should be considered in the design and development of the college engineering courses that enable students to facilitate their problem-solving attitude and improve academic achievement.

엔드밀 변위에 의한 공구파손검출

이승일(Seung-Il Lee),맹민재(Min-Jae Maeng),정준기(Joon-Ki Chung) 한국공작기계학회 1999 한국공작기계학회지 Vol.8 No.2

밀링가공에서 절삭유를 이용한 AE 신호의 검출

정준기,맹민재 弘益大學校 科學技術硏究所 1997 科學技術硏究論文集 Vol.8 No.-

In order to achieve the automation and untended system of manufacturing process, it is necessary that the monitoring system check up the disorder of machine tool. In this study, the method which uses acoustic emission(AE) signal is proposed to monitor the tool fracture in the milling process. In order to detect the AE-signal from the cutting zone directly, the AE-sensor is installed in the cutting oil supply device. Due to the tool fracture, the amplitude level of AE-signal at the beginning of tool-workpiece contact increases with the progressing cutting time. Using this phenomena, a practical monitoring algorithm has been developed. The practical method was also proposed to detect the tool fracture.

초경합금의 와이어 방전가공에 의한 특성

맹민재 한국산업안전학회 2001 한국안전학회지 Vol.16 No.4

Wire electrical discharge machining experiments are conducted to investigate characteristics of acoustic emission (AE) and electrical discharge energy due to current peak (I_p), pulse on time(τ_(on)). The AE signals are obtained with a sensor attached to workpiece side. Machining states are identified with scanning electron microscopy and residual stress analyzer. It is demonstrated that the residual stress provide reliable informations about the machining states. Moreover, machining states can be detected successfully using both the residual stress and AE count rate.