• 한국재료학회지
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• 제12권5호
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• pp.359-362
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• 2002

DBPAS has been used to characterize atomic level defect structures in materials. In this investigation the numerical analysis of the Doppler spectra was restricted to the determination of the shape parameter, S, defined as the ratio between the total amount of counts in a central portion of the spectrum and the total amount of counts. As samples were exposed by X-ray increasing from 3, 6, and 9 Gy with 6 MV, and 10 MV each and also by E-beam increasing the energies with 6 MeV, 9 MeV, 12 MeV, and 20 MeV. The S-parameter values were increased as increasing the exposed time and the energies. The S-parameters of the large and small size grains in $CaWO_4$ were measured. The S-parameter of the small size grains in $CaWO_4$ was resulted in larger values.

• 센서학회지
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• 제15권5호
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• pp.328-333
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• 2006

Magnetic Flux Leakage (MFL) methods are widely employed for the nondestructive evaluation (NDE) of gas pipelines. In the application of MFL pipeline inspection technology, corrosion anomalies are detected and identified via their leakage filed due to changes in wall thickness. The gas industry is keenly interested in automating the interpretation process, because a large amount of data to be analyzed is generated for in-line inspection. This paper presents a novel approach to the tasks of data segmentation, feature extraction and depth estimation from gas pipelines. Also, we will show that the proposed method successfully identifying artificial defects.

• 전기학회논문지
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• 제58권12호
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• pp.2532-2537
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• 2009

For defect characterization in steam generator tubes in nuclear power plant, artificial neural network has been extensively used to classify defect types. In this paper, we study the effectiveness of Bagging for improving the performance of neural network for the classification of tube defects. Bagging is a method that combines outputs of many neural networks that were trained separately with different training data set. By varying the number of neurons in the hidden layer, we carry out computer simulations in order to compare the classification performance of bagging neural network and single neural network. From the experiments, we found that the performance of bagging neural network is superior to the average performance of single neural network in most cases.

• Journal of Magnetics
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• 제18권3호
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• pp.357-360
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• 2013

A modified SQI method using magnetic leakage flux (MFL) signal for underground gas pipelines' defect detection and characterization is presented in this paper. Raw signals gathered using MFL signals include many unexpected noises and high frequency signals, uneven background signals, signals caused by real defects, etc. The MFL signals of defect free pipelines primarily consist of two kinds of signals, uneven low frequency signals and uncertain high frequency noises. Leakage flux signals caused by defects are added to the case of pipelines having defects. Even though the SQI (Self Quotient Image) is a useful tool to gradually remove the varying backgrounds as well as to characterize the defects, it uses the division and floating point operations. A modified SQI having low computational complexity without time-consuming division operations is presented in this paper. By using defects carved in real pipelines in the pipeline simulation facility (PSF) and real MFL data, the performance of the proposed method is compared with that of the original SQI.

• Korean Journal of Radiology
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• 제22권11호
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• pp.1894-1908
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• 2021

Double outlet right ventricle (DORV) is a relatively common congenital heart disease in which both great arteries are connected completely or predominantly to the morphologic RV. Unlike other congenital heart diseases, DORV demonstrates various anatomic and hemodynamic subtypes, mimicking ventricular septal defect, tetralogy of Fallot, transposition of the great arteries, and functional single ventricle. Because different surgical strategies are applied to different subtypes of DORV with ventricular septal defects, a detailed assessment of intracardiac anatomy should be performed preoperatively. Due to high spatial and contrast resolutions, cardiac CT can provide an accurate characterization of various intracardiac morphologic features of DORV. In this pictorial essay, major anatomic factors affecting surgical decision-making in DORV with ventricular septal defects were comprehensively reviewed using three-dimensional cardiac CT data. In addition, the surgical procedures available for these patients and major postoperative complications are described.

• 소성∙가공
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• 제22권5호
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• pp.275-279
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• 2013

The tube hydroforming process has received much attention in the automotive industry because of its advantages compared to conventional manufacturing technologies. A wide range of products such as sub-frames, camshafts, radiator frames, axles and crankshafts are made by hydroforming process. The hydroformed parts often need to be structurally joined to other components during assembly. Therefore, these automotive parts need to be manufactured with a localized attachment flange. In this study, FE forming analyses of a part with a rectangular flanged shape was performed with Dynaform 5.5. Using the optimized conditions determined numerically, hydroforming experiments were performed. Then, the characterization of defects was analyzed. Finally, the accuracy of the optimized internal pressure condition as well as that of the initial ram position were evaluated. The results demonstrated that flanged parts can be successfully produced using the tube hydroforming process.

• 한국진공학회지
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• 제3권2호
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• pp.203-206
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• 1994

동시증착법으로 성장한 CuIn3Se5 박막의 구조 및 광학적 특성을 XRD, SEM 광투과 및 광반사 측정으로부터 조사하였다. XRD 측정에 의하면 CuIn3Se5 는 정열된 Cu 빈자리와 Cuqls자리에 in으로 대 치되는 defect chalcopyrite 구조임이 확인디었다. 또한 광흡수 측정으로부터 CuIn3Se5 는 금지대내에서 직접 전이에 의한 광흡수 특성을 보여주며 이때 에너지띠 간격은 1.27ev 이었다. CuIn3Se5 박막에 대한 연구결과들은 CuInSe2 의 결과들과 비교하여 논의하였다.

• 한국공작기계학회논문집
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• 제14권3호
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• pp.96-102
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• 2005

Acoustic Emission(AE) technique has been applied to not only material characterization evaluation but also on-line monitoring of the structural integrity. The AE source location technique is very important to identify the source, such as crack, leak detection. Since the AE waveforms obtained from sensors are very difficult to distinguish the defect signals, therefore, it is necessary to consider the signal analysis of the transient wave-form. In this study, we have divided the region of interest into a set finite elements, and calculated the arrival time differences between sensors by using the velocities at every degree from 0 to 90. A new technique for the source location of acoustic emission in fiberboard plates has been studied by introducing Wavelet Transform(WT) do-noising technique. WT is a powerful tool for processing transient signals with temporally varying spectra. If the WT de-noising was employed, we could successfully filter out the errors of source location in fiberboard plates by arrival time difference method. The accuracy of source location appeared to be significantly improved.

• 한국정보통신학회논문지
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• 제20권11호
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• pp.2085-2092
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• 2016

IC 기판의 가장 중요한 성질들의 하나는 넓은 영역에 걸쳐 균일해야만 한다는 것이다. 웨이퍼 결함 분석의 다양한 물리적 접근 방법 중에서 적외선 조사 기법에 특별한 관심이 모아지고 있다. 특히, 높은 공간적 분해력을 가지고 있는 근적외선 흡수 방법은 반-절연 GaAs 내의 결함들을 직접적으로 관찰하는데 이용되고 있다. 적외선 전송에 기초를 둔 이 기법은 신속하고 비파괴 적이다. 이 방법은, 직접적으로 GaAs 반도체의 적외선 영상은 결함의 광흡수 작용에 기인한 것임을 밝히고 있다. 반-절연 GaAs 내의 EL2에 관련된, 비 균일 적으로 분포된 결함들의 적외선 흡수 영상에서 콘트라스트가 반전되는 현상에 대해 새로운 모델을 제시하고 있다. 저온 포토퀀칭 실험은, 직접적인 방법으로, GaAs 웨이퍼의 콘트라스트 반전 영상은 밴드갭의 지엽적인 변동이나 전하 재분포에 의한 것이 아니라 흡수와 산란의 두 메커니즘에 의한 것임을 증명하고 있다.

• Journal of Microbiology
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• 제44권5호
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• pp.523-529
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• 2006

OSH3 is one of the seven yeast homologues of the oxysterol binding proteins (OSBPs) which have the major binding affinity to the oxysterols and function as regulator of cholesterol biosynthesis in mammals. Mutational analysis of OSH3 showed that OSH3 plays a regulatory role in the yeast-to-hyphal transition through its oxysterol-binding domain in Saccharomyces cerevisiae. The OSH3 gene was also identified in the pathogenic yeast Candida albicans. Deletion of OSH3 caused a defect in the filamentous growth, which is the major cause of the C. albicans pathogencity. The filamentation defect of the mutation in the MAPK-associated transcription factor, namely $cph1{\Delta}$ was suppressed by overexpression of OSH3. These findings suggest the regulatory roles of OSH3 in the yeast filamentous growth and the functional conservations of OSH3 in S. cerevisiae and C. albicans.