• Journal of Welding and Joining
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• v.11 no.2
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• pp.1-12
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• 1993

용접과 관련되는 분야에서, 재료평가와 비파괴 검사법으로서의 Acoustic Emission의 응용을 살펴 보았다. 재료 평가법으로서의 AE는 다른 시험방법들이 검출해 내지 못하는 재료 내부에서의 미시적인 현상들을 정량적으로 평가할 수 있는 장점을 가지고 있다. 앞으로 새로운 용접재료의 개발이라든지, 고도의 신뢰성이 요구되는 용접부위의 정량적인 평가를 위해서 AE의 응용은 중요한 정보들을 제공하게 될 것이다. 한편 용접구조물의 비파괴적 평가법으로서의 AE는 균열의 동적인 거동 및 균열의 위치를 검지할 수 있다는 장점 때문에 응용범위는 더욱 넓어질 것이다. 여기서 유의하여야 할 점은, 목적으로 하는 AE신호를 수만배 까지 증폭시키는 과정에서 환경잡음의 영향을 무시할 수 없는 경우에는 우선적으로 잡음을 적극적으로 제거하는 고도의 연구도 함께 병행되어야 한다는 것이다.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.2 no.3
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• pp.34-40
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• 2003

This paper describes evaluation and monitoring methods of machining characteristics for developed micro grooving machine. Experiments were conducted under various process conditions such as spindle revolution speed, feed rates and depth of groove V and U shape of blade and STD11 were used in this experiment. The status of grooving was evaluated through analysis of the Acoustic emission (AE) signal resulted in each process condition. Based on the analysis, this paper examined the possibility of monitoring adapting fuzzy logic. In conclusion, this paper presented the possibility of monitoring in process adapting AE technology and appropriate micro grooving condition.

• Journal of Power System Engineering
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• v.3 no.2
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• pp.42-50
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• 1999

In recent years, composite materials like CFRP are increasingly used in various fields of engineering because of their unique properties which offer a high strength/density and high modulus/density. When CFRP structures are manufactured in drilling processes which are frequently practiced in an Industry, they bring on the delaminations sometimes. So, acoustic emission(AE) techniques were used for a condition monitoring of the drilling process in CFRP. In this study, the AE from CFRP estimated the delamination which reduces the strength and load carrying capacity under the drilling process and the initial delamination were well caught and measured by a video camera. From the results, it was found the relationships between failure mechanism of CFRP delamination and AE characteristics as like amplitude and count.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.17 no.4
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• pp.42-47
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• 2009

Recently, the wide range of the composite materials is used for the making airplanes, trains and automobiles body for the lightweight. Despite having complex structures, composite materials usually have well defined mechanical characteristics. However, composite materials are difficult to understand the fracture mechanism clearly by simple mechanical test. Nondestructive evaluation (NDE) combined with mechanical testing can play a more important role and especially Acoustic Emission Testing (AET) would become known to be a useful tool to assess damage and fracture behavior of composites. In this study The experiment was performed to acquire the acoustic emission signal during tensile test using unidirectional CFRP specimen and the data was analyzed the acoustic emission parameters with the waveform.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.4
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• pp.443-452
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• 2004

In recent year, composite materials are increasingly used in various fields of engineering because of its superior properties. The relationships of between crack propagation and AE characteristics fer CFRP plain woven laminate composites are examined. AE signals are measured during the fracture behavior tests. The purpose of study is to estimate the crack extension behavior with AE characteristics according to the load orientation fur plain woven CFRP laminate composite.

• The Korean Nurse
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• v.9 no.1 s.45
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• pp.11-13
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• 1970

• 대한세포병리학회:학술대회논문집
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• 1991.06a
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• pp.6.2-7
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• 1991

• Journal of Korean Orthopaedic Sports Medicine
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• v.11 no.2
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• pp.92-95
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• 2012

Iliacus muscle tears are a rare injury seen after the high-energy trauma or as a result of low-energy injuries in patients with a bleeding diathesis as coagulopathy, receiving anticoagulation therapy and hemophiliac. Femoral nerve palsy due to compression from a hematoma by iliacus muscle rupture are rarely reported. Routine evaluation includes MRI to confirm and define the pathologic abnormality supplemented by EMG and nerve conduction studies to evaluate patterns and extent of femoral nerve injury. Hematologic evaluation for bleeding diathesis may preceded, if suspicion of coagulopathy is present. We report the case of a healthy 32-year-old male with iliacus rupture and concomitant femoral nerve palsy sustained by kicking motion during soccer game. After 6 months of observation with non-operative treatment regimen, satisfactory results were obtained, so we report it with a review of the literatures.

• Journal of Advanced Marine Engineering and Technology
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• v.17 no.4
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• pp.38-48
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• 1993

A study on friction welding of stainless steel bar(SUS431) to chrome molybdenum steel bar(SCM21) was accomplished experimentally through analysis for relations among friction welding conditions, tension test, hardness test, microstructure test and acoustic emission test. The results obtained are summarized as follows ; 1. Through friction welding of SUS431 bar to SCM21 bar, the optimum welding condition by considering on strength and toughness was found to be the range of heating time of 3-5 sec when the number of rotating speed of 2000rpm, heating pressure of 10kg/$mm^2$, and upsetting time of 4 sec. 2. Quantitative ralationship was identified between heating time($T_1$, sec) and tensile strength (${\sigma},\;kgf/mm^2$) of the friction welded joint and the relation equation is $\sigma$=52.62$T_1{^{0.06}}$. 3. Through AE test, quantitative relationship was confirmed between heating time($T_1$, sec) and total AE(N, counts) during welding, and the relation is computed as follows ; N=30413.6$e^{0.06T1}$. 4. It was confirmed that the quantitative ralationship exists between the tensile strength of the welded joints and AE cumulative counts. And the relation is computed as the following ; ${\sigma}$=16.37(ln N)- 116.4. 5. When ONZ=36500-41500 counts by $OT_1Z$=3~5sec, it was identified by experiment that the range of welded joint tensile strength is 55.6-57.7kgf/$mm^2$/ whose joint efficiency is more than 100%, and it was experimentally confirmed that the real-time nondestructive quality(strength) evaluation for the friction welded joints could be possible by acoustic emission technique.

• Journal of the Korean Society for Nondestructive Testing
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• v.7 no.2
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• pp.42-47
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• 1988

The off-axis tensile strength of the unidirectional carbon fiber reinforced plastic and the residual strength of impact damaged CFRP were measured and compared with the stress wave factor (SWF) of the specimens. The SWF values were measured to be decreased with the strength reduction in both cases and found to be useful for the nondestructive strength evaluation of unidirectional CFRP. The failure behaviour of the unidirectional CFRP during off-axis tensile testing was also monitored by acoustic emission(AE) method. The AE energy release showed the characteristic feature depending on the off-axis angle and this result was analyzed to be caused by the difference of the expected failure mode depending on the off-axis angle. The failure mode of CFRP was found to be analyzed by investigation of the peak amplitude distribution of AE.