• 한국정밀공학회지
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• 제12권9호
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• pp.74-85
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• 1995

The purpose of this paper is to evaluate the grade of WA vitrified and resinoid bond grinding wheels by the sue of AE measuring system. When the manufactured 48 kinds of specimens were scratched by the method of OKOSHI'S grade test, the relationship between the amount of bit scratch depth of grinding wheel specimens and the character- istics of AE signals, and the relationship of AE counts and grade were considered as fololws; (1) The higher the grades are AE cumlulative event counts N and AE event count rate n, the smaller the values tend to be. But A $E_{rms}$is in reverse. (2) In the case of same grade, the smaller the grain size is, the higher the value of AE cumulative event counts N and A $E_{rms}$is results of comparison and observation. The grinding wheel with lower elasticity and with higher percentage of pore detected higher value of AE cumula- tive event counts N than with higher elasticity and lower percentage of pore. But A $E_{rms}$ is in reverse. (3) AE cumulative event counts N and bit scratch depth h have normally one to one correspondence. (4) It can be expected that quantitative evaluations of grade by using AE have been carried out by the wave observation of AE signal in line with the relationship between load speed of bit and AE cumulative event counts N & AE event count rate n.' AE event count rate n.ate n.

• 한국생산제조학회지
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• 제6권2호
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• pp.112-118
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• 1997

Characteristics of AE(Acoustic Emission) signal is related to cutting conditions, tool materials, and tool geometry in metal cutting. Relation between AE signal and tool wear was investigated experimentally. Experiment is carried out by interrupted cutting for SCM420 workpiece with TiN coating tool on HSS material. AE RMS voltage and count per event were increased according to tool wear. The major results are as follows : 1) AE RMS value is nearly constant as cutting speed changes, but is rapidly increase as feed rate increases. 2) AE RMS value and Count per Event increase as tool wear increases. 3) It is more effective to monitor tool wear by Incremental rate of AE RMS value than by Incremental rate of count per event.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 1995년도 춘계학술대회 논문집
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• pp.174-180
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• 1995

• 한국가구학회지
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• 제10권2호
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• pp.73-78
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• 1999

This paper describes the relationship between the bending strength properties of sloped finger-jointed woods and the acoustic emissions(AEs) generated during the test. Rhus verniciflua pieces were cut in sloped-finger types and glued with three kinds of adhesives(polyvinyl acetate, polyvinyl-acryl acetate and oilic urethane resin). The slope ratios of finger joints were 0, 1.0, 1.5, and 2.0. The AE cumulative event count and cumulative count were measured during the bending test. The results were as follows: The lower the bending strength(load) was, the generation time of AE event count got and the higher the increasing rate of AE event count became in the sloped finger-jointed specimens bonded with polyvinyl acetate, polyvinyl-acryl acetate oilic urethane resin adhesives. Therefore, the slope from load-AE cumulative event count was very steep. The patterns of AE event count and count were very similar. The relationship between the MOR and the AE parameter from load and AE cumulatve event count in the early stage of the sloped finger-jointed specimens bonded with polyvinyl acetate, polyvinyl-acryl and oilic urethane resin adhesives was much greater than that between the MOE and the MOR. Therefore, the AE signals obtained during bending test are useful for estimating the strength of sloped finger-jointed Rhus verniciflua specimens.

• Journal of the Korean Wood Science and Technology
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• 제27권1호
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• pp.30-36
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• 1999

소나무를 재료로 경사핑거접합법으로 레소시놀계수지, 유용성 우레탄수지, 초산비닐수지, 초산비닐과 아크릴을 혼합한 수지접착제롤 사용하여 제작한 시험재의 휨강도 성능과 휨 시험시 발생하는 AE 특성에 대한 연구결과는 다음과 같다. 초산 비닐, 유용성 우레탄 수지접착제를 사용한 소나무경사 핑거접합재의 하중과 AE 사상총수는 휨 강도가 낮을수록 빠른 시기부터 AE가 발생하고 AE의 증가속도가 빨라 하중-AE 사상총수의 관계곡선의 기울기가 급격하게 나타났다. 레소시놀 수지 접착제로 제작한 시편은 아주 낮은 하중에서부터 하중이 증가함에 따라 연속적으로 AE가 발생하였고 발생수도 많았다. 경사 핑거접착제의 휨 하중과 AE 특성간에는 서로 잘 대응되어 휨강도 측정이나 보정은 휨 탄성계수로서는 예측이 어렵지만 하중과 AE, 사상총수의 초기 치로부터 얻어지는 AE지표 치로서 휨 강도의 예측이나 보증이 가능 할 것으로 판단된다.

• 비파괴검사학회지
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• 제8권1호
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• pp.12-21
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• 1988

The behaviour of pressure vessel made of SS41 steel was investigated during hydrotest. AE tests were carried out for the vessels in as-manufactured, V-notched and weld-cracked state using microcomputer-based AE instrumentation. The following results were obtained: 1) In the case of source location using cylindrical program, to minimize the error of source location, the difference of max. Delta T values measured from each sensor should be kept as small as possible. 2) When crack grew, AE event rate increased continuously but AE event from the inclusions occurred intermittently, so by analyzing event rate, the source of AE could be derived. 3) From the spot welding part of supporter, many events with low energy occurred independent of Kaiser effect, which could be confirmed by analyzing energy parameter. 4) The b-value from the tensile specimen of was lower than that from normal specimen and the b-value from crack propagation was lower than that from deformation, so by analyzing peak amplitude distribution, the source mechanism could be derived from the b-value.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1995년도 춘계학술대회 논문집
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• pp.124-130
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• 1995

연삭작업에 있어서 요구되는 가공능률과 가공정밀도를 얻기 위해서는 적절한 결합도를 갖는 연삭숫돌을 선택하 는 것이 중요한 요건이 된다. 본 연구에서는 결합도를 평가하기 위한 일정한 기준을 설정할 목적으로 AE계측 시스템을 이용하여 대월식결합도시험방법에 따라 연삭숫돌표면의 일부를 파괴시켰을 때 발생되는 AE신호를 검출 하고 연삭숫돌의 파괴량과 AE 신호특성과의 관계 및 AE를 이용한 결합도평가의 가능성을 검토하였다.

• 비파괴검사학회지
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• 제16권2호
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• pp.79-85
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• 1996

복합 재료의 single-lap 및 double-strap adhesive bonding joint 시험편에서 피로 및 인장시험시 방출되는 AE 신호의 분석에 의한 피로 수명 예측 및 파괴 과정의 감시에 대한 연구를 수행하였다. Bonding 시험편의 피로시험시 AE event의 발생양상은 피로에 의해 축적된 elastic strain energy의 방출과 관계되며, peak amplitude가 높고 event duration이 긴 event의 발생 영역과 peak amplitude가 낮고 event duration이 짧으나 많은 event가 발생되는 영역으로 나눌 수 있었다. 그리고 두 영역 사이의 경계 cycle은 피로 수명의 70-80% 근방에 존재하였으며, 이를 이용한다면 피로 수명의 예측이 가능하리라 판단된다.

• 산업기술연구
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• 제19권
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• pp.197-208
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• 1999

The process of localization of cracks and movement of the fracture process zone(FPZ) was studied using the acoustic-emission(AE) techniques. The rate of AE events and sources of AE activity were studied for mortar and rock specimens loaded in uniaxial compression. A series of transducers could be used to detect and AE activity. Based on the time differences between detection of the event at different transducers, source of AE activity could be detected. The rate of AE events increased sharply before peak load. The highest rate occurred just after peak load was attained. The effective crack length estimated from the modified linear-elastic fracture mechanics seemed consistent with the optical and AE measurements.

• 대한기계학회논문집
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• 제12권2호
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• pp.241-251
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• 1988

본 연구에서는 숫돌입자, 결합자 및 기공으로 조성된 연삭숫돌의 구조를 다공질 포성체로 보고, WA계 비트리파이드(vitrified) 및 레지노이드(resinoid) 결합자의 연삭숫돌시험편에 대하여 AE 계측방법을 이용한 인장, 압축, 굽힘 및 압렬시험을 실시하여 Babel과 Sines의 2축응력장해소이론과 연삭숫돌의 파괴조건을 관련시켜 평가함과 동시에, 이 때 검출되는 AE 신호 처리 파라미터(Parameter) 로부터 연삭숫돌의 자인자가 파괴강도 및 AE특성에 미치는 영향을 구명하여 파괴의 예지및 연삭숫돌수명의 예측가능성등의 파괴강도특성을 평가고찰하였다.