• Journal of Chest Surgery
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• v.14 no.3
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• pp.241-246
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• 1981

A series of 132 consecutive cases of secundum type atrial septal defect operated from 1963 to 1980 in the department of Thoracic Surgery of Seoul National University Hospital is analysed. The ages of the patients ranged from 12 months to 57 years and the ratio of men to women was 1 to 1.4. Clinical analysis revealed 33 patients [26%] were asymptomatic and 15 patients [12%]had congestive heart failure. Hemodynamic analysis revealed that severe pulmonary hypertension which is the most serious risk factor is ASD developed in 10 patients [9%] and pulmonary artery pressure significantly increased after the age of 20 years. There were 10 patients with sinus venosus defect and 7 patients with partial anomalous pulmonary venous return. The operative mortality was 2.2%.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.25 no.6
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• pp.7-11
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• 2002

This paper estimates defect and outbreak probabilities of each individual component from some subset of masked data where the exact component causing system failure might be unknown. A system consists of k components that fails whenever there is a defect in at least one of the components. Due to cost and time constraints it is not feasible to learn exactly which components are defective. Because, test procedures ascertain that the defective components belong to some subset of the k components. This phenomenon is termed masking. We describe a, b, c type in which a sample of masked subsets is subjected to intensive failure analysis. This recorded data of a, b, c type enables maximum likelihood estimation of defect probability of each individual component and leads to outbreak of the defective components in future masked failures.

• Journal of Chest Surgery
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• v.21 no.4
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• pp.630-640
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• 1988

We clinically evaluated 222 cases of ventricular septal defect which we experienced at Department of Thoracic and Cardiovascular Surgery, Pusan National University Hospital between July 1981 and March 1988. These patients were occupied 46.2% of all congenital heart disease operated on its same period. Of 222 cases, 132 patients were male and 90 patients were female. Their age distribution ranged from 8 months to 34 years of age and their mean age was 10.3 years. Among these patients, 86 patients had associated cardiac anomalies, which were patent foramen ovale 43 cases[19.5%], Atrial septal defect 18 cases[8.1%], patent ductus arteriosus 8 cases[3.6%], aortic insufficiency 7 cases[3.2%], infundibular pulmonary stenosis 5 cases[2.3%] and etc. There was statistically significant correlationship between VSD size and Qp/Qs, Rp/Rs, Pp/Ps respectively. All cases were operated under cardiopulmonary bypass and 157 patients[70.7%] would be corrected through right atrial approach. 158 patients[71.2%] underwent closure of ventricular septal defect with primary closure and the remained patients[28.8%] with patch closure. In anatomical classification by Kirklin, type I constituted 23.4%, type II 73.4%, type III 0.5%, type I and type II 1.4%, and type II and type III 1.4%. Important postoperative EGG changes were noted in 57 cases[25.7%] and incomplete right bundle branch block was most common[12.6%]. 54 patients[24.3%] developed minor and major postoperative complications and 9 patients died of several complications and overall operative mortality was 4.1%.

• The KIPS Transactions:PartD
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• v.15D no.3
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• pp.321-326
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• 2008

The software defects that are not found in the course of a project frequently appear during the conduct of the maintenance procedure after the complete development of the software. As the frequency of surfacing of defects during the maintenance procedure increases, the cost likewise increases, and the quality and customer reliability decreases. The defect rate will go down only if cause analysis and process improvement are constantly performed. This study embodies the defect tracking system (DTS) by considering the Pareto principle: that most defects are repetitions of defects that have previously occurred. Based on the records of previously occurring defects found during the conduct of a maintenance procedure, DTS tracks the causes of the software defects and provides the developer, operator, and maintenance engineer with the basic data for the improvement of the software concerned so that the defect will no longer be manifested or repeated. The basic function of DTS is to analyze the defect type, provide the measurement index for it, and aggregate the program defect type. Doing these will pave the way for the full correction of all the defects of a software as it will enable the defect correction team to check the measured defect type. When DTS was applied in the software configuration management system of the W company, around 65% of all its software defects were corrected.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.3
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• pp.683-688
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• 2015

Recently, various static analysis tools for software defect detection are becoming widely used in practice. However, there is little public information of the most frequent defects in commercial areas until now. In this paper, we analyze the defects found by CodeSonar, a static analysis tool that finds defects in C/C++, Java programs. So we report the most frequent defects by various aspects in Dongnam area, Korea.

• Journal of the Korean Society for Nondestructive Testing
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• v.27 no.5
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• pp.383-392
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• 2007

In this paper, we study the prediction of depth and width of a defect in steam generator tube in nuclear power plant using neural network. To this end, we first generate eddy current testing (ECT) signals for 4 defect patterns of SG tube: I-In type, I-Out type, V-In type, and V-Out type. In particular, we generate 400 ECT signals for various widths and depths for each defect type by the numerical analysis program based on finite element modeling. From those generated ECT signals, we extract new feature vectors for the prediction of defect size, which include the angle between the two points where the maximum impedance and half the maximum impedance are achieved. Using the extracted feature vector, multi-layer perceptron with one hidden layer is used to predict the size of defects. Through the computer simulation study, it is shown that the proposed method achieves decent prediction performance in terms of maximum error and mean absolute percentage error (MAPE).

• Transactions of the Korean Society of Mechanical Engineers A
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• v.29 no.7 s.238
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• pp.947-954
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• 2005

The purpose of this study is to develop failure pressure evaluation models, which are applicable to straight pipes and elbows containing an internally wall thinning defect induced by flow-accelerated-corrosion (FAC). In this study, thus, three dimensional finite element (FE) analyses are performed to investigate the dependences of failure pressure of internally wall thinned pipe on the defect shape, the pipe geometry, and the defect location and bend radius of elbow. Also, the existing failure pressure assessment models for externally wall thinned pipes are examined. Based on these, the new models for assessing failure pressure of piping components with an internally wall thinning defect are proposed. Comparison of failure pressure, predicted by proposed models, with FE analysis result shows good agreement regardless of pipe type, defect shape, and defect location and bend radius.

• Journal of the Korean Society for Nondestructive Testing
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• v.33 no.6
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• pp.505-510
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• 2013

An encircling send-receive type pulsed eddy current (PEC) probe is designed for use in aluminum tube inspection. When bare receive coils located away from the exciter were used, the peak time of the signal did not change although the distance from the exciter increased. This is because the magnetic flux from the exciter coil directly affects the receive coil signal. Therefore, in this work, both the exciter and the sensor coils were shielded in order to reduce the influence of direct flux from the exciter coil. Numerical simulation with the designed shielded encircling PEC probe showed the corresponding increase of the peak time as the sensor distance increased. Ferrite and carbon steel shields were compared and results of the ferrite shielding showed a slightly stronger peak value and a quicker peak time than those of the carbon steel shielding. Simulation results showed that the peak value increased as the defect size (such as depth and length) increased regardless of the sensor location. To decide a proper sensor location, the sensitivity of the peak value to defect size variation was investigated and found that the normalized peak value was more sensitive to defect size variation when the sensor was located closer to the exciter.

• Journal of Chest Surgery
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• v.18 no.2
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• pp.151-156
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• 1985

A clinical analysis was done on 50 cases of ventricular septal defect, operated from April 1981 to March 1984 at the department of Thoracic and Cardiovascular Surgery, School of Medicine, Keimyung University. Among 50 cases, 34 cases were males and 16 cases were females. Their age ranged from 1 to 26 years and the mean age was 9.7 years. The main symptoms at admission were frequent upper respiratory infection [50%], exertional dyspnea [42%] and palpitation [34%]. In anatomical classification by Kirklin, type I constituted 20%, type II 76%, type IV 4%. Associated congenital cardiac lesions were pulmonic stenosis [6 cases], patent foramen ovale [5 cases], aortic insufficiency [3 cases] and persistent left superior vena cava [1 case]. When a normal electrocardiogram pattern was present, Qp/Qs, Rp/Rs and pulmonary artery systolic pressure and Pp/Ps were relatively low. Among cases of above 1 cm2/M2 BSA in size of defect, Pp/Ps and pulmonary artery systolic pressure were increased than the cases of below 1 cm2/M2 BSA [P=0.01]. The postoperative right bundle branch block was occurred in 21 cases [75%] among 28 cases of right ventriculotomy approach. The operative mortality was 2% [1 case] among 50 cases and complication rate was 14% [7 cases].

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.637-642
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• 2011

Rails are subjected to damage from rolling contact fatigue, which leads to defects such as cracks. Rolling contact fatigue damages on the surface of rail such as head check, squats are one of growing problems. Another form of rail surface damage, known as "Ballast imprint" has become apparent. This form of damage is associated with ballast particles becoming trapped between the wheel and the surface of rail. These defects are still one of the key reasons for rail maintenance and replacement. In this study, we have investigated whether the ballast imprint is an initiator of head check type cracks and effect of defect size using Finite element analysis. The FE analysis were used to investigate stresses and strains in subsurface of defects according to variation of defect size. Based on loading cycles obtained from FE analysis, fatigue analysis for each point was carried out.