• Journal of the Korea Furniture Society
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• v.10 no.2
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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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• v.27 no.1
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• pp.30-36
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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. Pinus densiflora pieces were cut in sloped-finger types and glued with four kinds of adhesives (polyvinyl acetate, polyvinyl-aeryl, oilic urethane and resorcinol-phenol resin). The results were as follows: The lower the bending strength(load) was, the earlier 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 and oilic urethane resin adhesives. Therefore, the slope from load-AE cumulative event count curve was very steep. The AE event count for resorcinol-phenol resin adhesive obtained even from low load level was abundant. The AE event count continuously increased as load increased and the event count was much more than one in the other conditions. The slope from load-AE cumulative event count curve was very gentle compared with other conditions. The patterns of AE event count and count were very similar. The relationship between the MOR and the AE parameter from load and AE cumulative event count in the early stage of the sloped finger-jointed specimens bonded with polyvinyl acetate, oilic urethane and resorcinol-phenol 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 specimens.

• Journal of the Korean Society for Precision Engineering
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• v.12 no.9
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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.

• Journal of the Korean Wood Science and Technology
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• v.31 no.2
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• pp.84-91
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• 2003

In this study, the three species (Populus euramericana, Pinus densiflora and Quercus variabilis) were cut to difference (0, 0.15, 0.3, 0.45 mm) between the size of tip and that of root of the finger (DSTR) and jointed with poly vinyl acetate (PVA) and resorcinol-phenol resin (RPR). We described the relationship between the bending strength properties of finger DSTR and the acoustic emission (AE) generated during the bending test. The results were as follows: The AE generation time of finger-jointed specimens with RPR adhesive was earlier than that with PVA adhesive. The AE cumulative event count of finger-jointed specimens with RPR adhesive continuously increased with increasing load and the event count was much more than that with PVA adhesive. Also, the AE cumulative event count for resorcinol-phenol resin adhesive obtained from low load level was abundant. The AE wave in finger-jointed specimens with RPR adhesive could be detected in the below proportional limit load. Therefore, AE signals from bending test are useful for the estimation of strength in finger DSTR specimens.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1995.03a
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• pp.174-180
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• 1995

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.04b
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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.

• Journal of Ocean Engineering and Technology
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• v.26 no.5
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• pp.5-10
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• 2012

In this study, carbon steel (A53) is used as the material for the pipes in a marine plant and ship industry. Welds are necessary to join the carbon steel, and the effect of this welding on the properties of the carbon steel has been studied by many researchers. In this study, the dynamic behavior of welded carbon steel was studied using an acoustic emission (AE) technique, which is a nondestructive test. There are numerous AE parameters that can be used to analyze the damage behavior of carbon steel by external loading. The AE parameters of energy, cumulative count, amplitude, and AE event were used, and each parameter was differentiated according to the degree of damage to the carbon steel. The energy showed a high level at the elastic range of the load curve, while the amplitude had the highest value at the hardening region. The cumulative count showed a growth tendency similar to the loading curve. In addition, an ultrasonic technique and hardness test were applied to evaluate the mechanical properties according to the base zone, HAZ region, and weld zone of the weld specimen. The velocity and attenuation ratio showed little change between zones, and an evaluation of the ultrasonic waves on each zone of the specimen was found to be a useful method to clarify the mechanical properties of the carbon steel.

• Transactions of the Korean Society of Mechanical Engineers
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• v.12 no.2
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• pp.241-251
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• 1988

The purpose of this paper is to evaluate fracture strength of WA-vitrified and resinoid bond grinding wheels by means of acoustic emission. The paper conducts tension test, compression test, splitting tensile test and bending test with AE measuring system. These tests have been carried out in accordance with the grain sizes and grades of grinding wheels. The fracture strength of grinding wheels is evaluated by the clarification of biaxal fracture criterion of Babel and Sines. It clarifies the influence of factors of grinding wheel upon AE characteristics and evaluates the predictability of life of grinding wheels and the perception of fracture.

• Proceedings of the Korean Nuclear Society Conference
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• 1996.05c
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• pp.145-150
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• 1996

Acoustic Emission (AE) technique was applied to stress corrosion cracking of Inconel 600 to investigate the AE capability of detecting crack growth and to obtain the relation between AE characteristics and crack mechanism. The specimens were heat-treated in two conditions (600$^{\circ}C$ for 30 hrs or 700 $^{\circ}C$ for 1 hr) and undergone CERT at two extension rates ( 2.5${\times}$10$^{-5}$ or 1.25${\times}$10$^{－4}$(mm/s)). It was found that the AE peak amplitude from plastic deformation was generally smaller than about 48dB (0.25mV), while Intergranular stress corrosion cracking (IGSCC) and ductile fracture produced higher values of 49 to 70dB (0.3mV to 3mV). The slopes of cumulative amplitude distribution (b-values) were linearly dependent on IGSCC susceptibility and the higher the susceptibility, the smaller the b-value. The monitoring of combined AE parameters such as event rate, amplitude, count and energy can provide effective means to clearly identify the transition from crack initiation and small crack growth to rapid growth of dominant cracks.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1349-1352
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• 2005

This paper is to investigate a defect for thermal barrier coating layers by acoustic emission method in 4-point bending test. The two-layer thermal barrier coating is composed of $150\mu{m}\;CoNiCrAlY\;bond\;coating\;by\;vacuum\;plasma\;spray(VPS)\;process\;and\;250\mu{m}\;ZrO_2-8wt%Y_2O_3$ ceramic coating layer by air plasma spray(APS) process on Inconel-718. The specimen prepared by cyclic thermal test(500, 1000, 2000cycle) at $1050^{\circ}C$ The AE monitoring system is composed of PICO type sensor, a wide band pre-amplifier(40dB), PC and AE DSP(16/32 PAC) board. The AE event, amplitude, Cumulative energy and count of coating specimens is evaluated according to cyclic thermal test.