• Journal of Chest Surgery
• /
• v.21 no.6
• /
• pp.1117-1123
• /
• 1988

Prolapse of the aortic valve is the main cause of insufficiency of the aortic valve as a complication of ventricular septal defect. Aortic insufficiency gets worse by the progress of prolapse of aortic valve due to lack of support of the valve and the hemodynamic effect of blood flow through the ventricular septal defect. This produces typical clinical picture, that may be serious and threatening when it is untreated. Type and timing for the surgical treatment of the ventricular septal defect with aortic insufficiency is considered. Among 113 ventricular septal defect, 9 patients of ventricular septal defect with associated aortic insufficiency were experienced from June. 1983 to June 1988 at the Department of Thoracic and Cardiovascular Surgery, Chon-Buk University Hospital. Male was 6 patients and female was 3 patients. Ages were from 7 years to 24years. 5 patients were from 10 to 19 years age. 3 patients were below 10 years age. The ratio of pulmonary blood flow to systemic f low [Qp/Qs] was 1.53 and in pulmonary vascular resistance, normal or slight increase was 7 patients, moderate 1 patient, and severe 1 patient. Ventricular septal defect was subpulmonic in 5 patients and infracristal in 4 patients. Prolapse of right coronary cusp was 7 patients, right and non coronary cusp 1 patient and non coronary cusp 1 patient. Teflon patch closure of ventricular septal defect was undertaken in 3 patients and primary closure in 1 patient. Among the 4 patients of defect closure alone, one patient performed valve replacement 7 months later due to progressive regurgitation and cardiac failure and the result was good. The other 3 patients were good result. Closure of ventricular septal defect and aortic valvuloplasty performed in 4 patients. 2 patients of these required valve replacement for the sudden intractable cardiac failure and died due to low cardiac output. The cause of intractable cardiac failure was tearing of repaired valve at the fixed site. The other 2 patients were good result. Closure of ventricular septal defect and valve replacement performed in 1 patient with good result.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2004.08a
• /
• pp.307-316
• /
• 2004

This study examined the cause of the wrinkle defect which is frequently encountered in wire rod rolling of low carbon steel$(C0.08\~0.13wt.\%)$. Even a small defect on the surface of rolled bars can easily develop into fatal cracks during cold heading process of low carbon steel, and it is therefore necessary to minimize inherent defects on the surface of hot rolled bars. Hot rolling process of low carbon steel was analyzed to identify the cause of the wrinkle defect in conjunction with FE analysis. The integrated analysis revealed that the wrinkle defect initiated in the first stage of rolling, and it was at the billet edge where severe deformation and drastic temperature drop were present. To elucidate the micro-mechanical mechanism of the wrinkle defect, hot compression tests were carried out at various temperatures and strain rates using Gleeble-3800. The surface profile of the each other compressed specimens was compared, and rough surface lines were observed at relatively low temperatures. Those surface defects can develop into wrinkles during multi-pass rolling. To control the wrinkle defect in rolling, it is necessary to design an adequate caliber which can minimize the loss of ductility, and thereby prevent flow localization. To use the result of this study fur other steels, the quantitative measure of the wrinkle defect and flow localization parameter should be proposed.

• Journal of Mechanical Science and Technology
• /
• v.18 no.9
• /
• pp.1493-1499
• /
• 2004

This paper describes the speckle shearing interferometry, a non-destructive optical method, for quantitative estimation of void defect and monitoring separation defect inside of a pneumatic tire. Previous shearing interferometry has not supplied quantitative result of inside defect, due to effective factors. In the study, factors related to the details of an inside defect are classified and optimized with pipeline simulator. The size and the shape of defect can be estimated accurately to find a critical point and also is closely related with shearing direction. The technique is applied for quantitative estimation of defects inside of a pneumatic tire. The actual traveling tire is monitored to reveal the cause of separation and the starting points. And also unknown void defects on tread are inspected and the size and shape of defects are estimated which has good agreement with the result of visual inspection.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.19 no.5
• /
• pp.82-90
• /
• 2020

Due to the complicated shape of the spider, the production method was changed from cold to warm forging. Finite element analysis was performed to predict the forging load and shape using the enclosed hydraulic die set. As the forging load increases due to the spider die volume, die stress analyses were performed to optimize the die design in order to reduce the die stress in various conditions. Large deformation while producing the complicated forging parts induces high forging load, which is one of the main parameters of the forging surface defects. The forging process was analyzed to find out the root cause of the surface defects generated during the spider production for various parameters, thereby revealing that the radius of die in the defect zone influenced the air trap depth, being the root cause of the surface defect. It was verified that die life was increased and the surface defect was eliminated by changing the die design during the mass production test.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2001.04a
• /
• pp.195-198
• /
• 2001

Backside defect of plate structure may grow due to fatigue or overload to cause critical failure during operation, so it is important to detect this kind of defect in line. For this purpose, nondestructive, non-contact and highly sensitive method is required. ESPI and Shearography are considered as useful method to satisfy these requirements. In this paper, the possibility of application of ESPI and Shearography to detect the backside defect of steel plate and to quantify the defect size was tested. For the experiment, some steel plates with defect on the backside were prepared. Experimental results for these plates showed that location and size of defect could be detected correctly by both of ESPI and Shearography.

• Carbon letters
• /
• v.16 no.3
• /
• pp.198-202
• /
• 2015

Carbon-supported Pt catalyst systems containing defect adsorption sites on the anode of direct methanol fuel cells were investigated, to elucidate the mechanisms of H₂ dissociation and carbon monoxide (CO) poisoning. Density functional theory calculations were carried out to determine the effect of defect sites located neighboring to or distant from the Pt catalyst on H₂ and CO adsorption properties, based on electronic properties such as adsorption energy and electronic band gap. Interestingly, the presence of neighboring defect sites led to a reduction of H₂ dissociation and CO poisoning due to atomic Pt filling the defect sites. At distant sites, H₂ dissociation was active on Pt, but CO filled the defect sites to form carbon π-π bonds, thus enhancing the oxidation of the carbon surface. It should be noted that defect sites can cause CO poisoning, thereby deactivating the anode gradually.

• Journal of the Korea Institute of Building Construction
• /
• v.13 no.5
• /
• pp.498-505
• /
• 2013

The main processes involved in a defect dispute are consulting, reviewing, and finally judging as an arbiter. This process of defect consulting produces a defect consulting report, but business practices and standards of judgment will differ among consultants, and have many problems. This study reviews the structure of a defect consulting report and considers the structure's problem, which is that it is not standardized. To achieve this, data of sixteen defect consulting report were collected involving defect lawsuit cases before or after 2010. The structure and index of the defect consulting reports were then reviewed, and the results are as follows. As for a structure based on fourteen index, there are suitable that judge a outline, a cost estimate data and a consulting work item by a consulting standard. Furthermore, analysis by each common parts and private parts is considered as appropriate about consulting items and estimate by standard. However, consulting item in construction progress and responsibility period for security that related on a cause and a responsibility of defect need to complement. Meanwhile, the first thing of issues are connected a defect consulting is urgent a standardization for a defect type.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.22 no.2
• /
• pp.148-155
• /
• 2014

Most truck fires breaking out on the expressway are directly damaged by fire destruction of truck and freight and many of them cause indirect damage such as serious traffic holdups. This study analyzed the fire causes and their liability of the 25-ton truck fire breaking out during expressway driving. This truck fire was caused by manufacturing defect of return spring of a braking system. The fire liability rested with a maker(manufacturer) rather than a truck owner or a driver and the maker also bore fire liability based on the Product Liability Law.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.44 no.1
• /
• pp.60-70
• /
• 2021

Recently, with the development of technologies for the fourth industrial revolution, convergence and complex technology are being applied to aircraft, electronic home appliances and mobile devices, and the number of parts used is increasing. Increasing the number of parts and the application of convergence technologies such as HW (hardware) and SW (software) are increasing the No Defect Found (NDF) phenomenon in which the defect is not reproduced or the cause of the defect cannot be identified in the subsequent investigation systems after the discovery of the defect in the product. The NDF phenomenon is a major problem when dealing with complex technical systems, and its consequences may be manifested in decreased safety and dependability and increased life cycle costs. Until now, NDF-related prior studies have been mainly focused on the NDF cost estimation, the cause and impact analysis of NDF in qualitative terms. And there have been no specific methodologies or examples of a working-level perspective to reduce NDF. The purpose of this study is to present a practical methodology for reducing NDF phenomena through data mining methods using quantitative data accumulated in the enterprise. In this study, we performed a cluster analysis using market defects and design-related variables of mobile devices. And then, by analyzing the characteristics of groups with high NDF ratios, we presented improvement directions in terms of design and after service policies. This is significant in solving NDF problems from a practical perspective in the company.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2007.08b
• /
• pp.1597-1599
• /
• 2007

In TFT-LCD, mura is a defect which degrades the display quality. The resistance difference between gate lines is the main cause of H-Block mura. Two methods could eliminate this defect. A thinner gate layer or gate fan-out pattern decrease mura level. H-Block mura has been reduced after implementing the new schemes.