• Elastomers and Composites
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• 제56권3호
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• pp.124-135
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• 2021

Evaluating service lives of rubber materials at certain temperatures requires a destructive method (typically using elongation at break). In this study, a non-destructive method based on hardness change rate was proposed for evaluating the service life of chloroprene rubber (CR). Compared to the destructive method, this non-destructive method ensures homogeneity of CR specimens and requires a small number of samples. Thermal accelerated degradation test was conducted on the CR specimens at 55, 70, 85, 100, and 125℃, and the tensile strength, elongation at break, and hardness were measured. The results of the experiment were compared to those of the accelerated life evaluation method proposed in this study. Comparing the analyzed lives in the high temperature region (70, 85, 100, and 125℃), the difference between the service lives for the destructive method (using the elongation at break) and non-destructive method (using the hardness) was approximately 0.1 year. Therefore, it was confirmed that the proposed non-destructive evaluation method based on hardness changes can evaluate the actual life of CR under thermally accelerated degradation conditions.

• 대한기계학회논문집
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• 제18권4호
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• pp.816-825
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• 1994

The purpose of this study is to develop the non-destructive material evaluation method of aluminum alloy base metal matrix composite(MMC) by ultrasonics. Five aluminum base MMC specimens were fabricated in which the fractional ratios of fiber were changed from 0% to 31%. Relations among acoustic properties, microstructural features and elastic constant were compared. The ultrasonic velocity method was useful for nondestructive elastic constant measurement of composite materials, since the method had as same accuracy as conventional strain measurement method. Furthermore, velocity, attenuation and backscattering behaviors for each specimen also related to fractional ratio of fiber and these relations could utilize ultrasonic non-destructive evaluation of fiber structure in MMC.

• Journal of Mechanical Science and Technology
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• 제19권3호
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• pp.820-825
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• 2005

This paper proposes non-destructive ESPI technique to evaluate inside defects of semiconductor package quantitatively. Inspection system consists of ESPI system, thermal loading system and adiabatic chamber. The technique has high feasibility in non-destructive testing of semiconductor and gives solutions to the drawbacks in previous technique, time-consuming and the difficulty of quantitative evaluation. In result, most of defects are classified in delamination, from which it is inferred to the insufficiency of adhesive strength between layers and nonhomogeneous heat spread. The $90\%$ of tested samples have a delamination defect started at the around of the chip which may be related to heat spread design.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2003년도 추계학술대회
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• pp.174-179
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• 2003

Non-destructive test on the size and depth of cracks has been required for the safety evaluation of structures. Ultrasonic method based on laser techniques is one of the most popular non-destructive methods which overwhelm PZT based tests. In the present paper, ultrasonic was generated by high powered Q switching Nd:YAG pulse laser. Experiments were carried out using Fabry-Perot interferometer which was intensively discussed in the present study.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2005년도 춘계학술대회 논문집
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• pp.71-76
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• 2005

The defects evaluation of the interior and the surface would be considered as vital characteristics in predicting the total life span of the steel structure. More importantly, the understandings in the interior composite of welding zone and the notifications in the presence, the formation, and the positioning of the non-metallic inclusion are necessary as well, since there were signs of relatively high defect frequency presented in the welding zone. The ultrasonic testing is a highly recommended technique chosen from among other techniques because of variety of advantages in conducting the non-destructive testing for the welding zone. However, the ultrasonic testing had technical disadvantages referred as followings; the problems due to the couplant between the PZT and the specimen, the formations that were miniature and complex, the moving subject, and the high temperature surrounding the specimen. This research was conducted to resolve the technical disadvantages of the contact ultrasonic testing by studying the non-contact ultrasonic testing where the ultrasonic waves were transferred by the laser, and revealing the specimen defects at its interior part and its surface part. The ultimate goal of this research was to develop a non-destructive evaluation applying the laser manipulated ultrasonic method for the steel structure.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2002년도 춘계학술대회 논문집
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• pp.191-194
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• 2002

The tensile properties of materials can be obtained just in accordance with conventional tensile testing methods which are described in several standards. However, the standard testing methods cannot be applicable due to the destructive testing procedure and specimen size requirement for some cases including on-service facility materials. Therefore, simple, non-destructive and advanced indentation technique was proposed. This test measures indentation load-depth curve during indentation and analyzes the mechanical properties related to deformation and fracture. In this paper, the research trend of non-destructive evaluation of tensile properties using advanced indentation system and its application fields are reviewed and discussed.

• 한국축산식품학회지
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• 제41권4호
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• pp.563-588
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• 2021

Increasing meat demand in terms of both quality and quantity in conjunction with feeding a growing population has resulted in regulatory agencies imposing stringent guidelines on meat quality and safety. Objective and accurate rapid non-destructive detection methods and evaluation techniques based on artificial intelligence have become the research hotspot in recent years and have been widely applied in the meat industry. Therefore, this review surveyed the key technologies of non-destructive detection for meat quality, mainly including ultrasonic technology, machine (computer) vision technology, near-infrared spectroscopy technology, hyperspectral technology, Raman spectra technology, and electronic nose/tongue. The technical characteristics and evaluation methods were compared and analyzed; the practical applications of non-destructive detection technologies in meat quality assessment were explored; and the current challenges and future research directions were discussed. The literature presented in this review clearly demonstrate that previous research on non-destructive technologies are of great significance to ensure consumers' urgent demand for high-quality meat by promoting automatic, real-time inspection and quality control in meat production. In the near future, with ever-growing application requirements and research developments, it is a trend to integrate such systems to provide effective solutions for various grain quality evaluation applications.

• Composites Research
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• 제17권1호
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• pp.1-9
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• 2004

본 연구에서는 타격음을 이용한 비파괴 검사법을 제안하였다. 제안된 방법(tapping sound analysis)은 건강한 구조물과 손상된 구조물의 타격음의 차이를 분석하여 구조물의 손상 유무를 판단하는 방법이다. 타격음의 직접적인 비교는 비효율적이므로 타격음으로부터 특성을 추출하기 위해 wavelet packet transform에 기반한 특성추출법을 제안하였다. 또한 추출된 특성 자료를 바탕으로 손상의 유무를 판단하는 지표로서 특성 지수를 정의하였다. 제안된 방법의 타당성을 밝히기 위해 실험적인 검증을 수행하였다. 복합재료를 이용하여 건강한 구조물과 손상된 구조물을 제작하고 타격음을 측정하였다. 제안된 손상 판단 기법을 이용한 결과로부터 특성 지수에 의한 손상 판단의 타당성을 밝혔다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2004년도 춘계 학술발표회 제16권1호
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• pp.392-395
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• 2004

When a concrete member is damaged by fire accident, it can lose its strength. And the degradation rate of losing its strength affected by many environmental conditions. But there is few research for equation for strength evaluation of fire-damaged concrete. Besides, it is impossible to destruct structural member from the building for the evaluation. So, I will suggest a new equation for strength evaluation of fire-damaged RC beam using non-destructive test. For this purpose, the researchers are exploring the performance of non-destructive testing methods using Ultrasonic test, Schmidt Hammer test and Coring test against fire damaged concrete specimen.

• 한국안전학회지
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• 제30권1호
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• pp.52-59
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• 2015

The aim of the paper is to introduce the statistical definition of the specified compressive strength of the concrete to be used for safety evaluation of the existing structure in domestic practice and to present the practical method to obtain the specified strength by utilizing the non-destructive test data as well as the limited number of core test data. The statistical definition of the specified compressive strength of concrete in the design codes is reviewed and the consistent formulations to statistically estimate the specified strength for assessment are described. In order to prevent estimating an unrealistically small value of the specified strength due to limited number of data, it is proposed that the information from the non-destructive test data is combined to that of the minimum core test data. The the sample mean, standard deviation and total number of concrete test are obtained from combined test data. The proposed procedures are applied to an example test data composed of the artificial numerical values and the actual evaluation data collected from the bridge assessment reports. The calculation results show that the proposed statistical estimation procedures yield reasonable values of the specified strength for assessment by applying the non-destructive test data in addition to the limited number of core test data.