• IE interfaces
• /
• v.23 no.2
• /
• pp.176-181
• /
• 2010

Warranty claim data analysis is a useful tool for the manufacturer because it contains many useful informations regarding reliability of the product in the real-world environments. Because of the nature of uncertainty and the incompleteness of data, some bias patterns are observed on warranty claim rate known as 'spikes'. Two types of spikes are considered. One is due to manufacturing-related failures. The other is caused by customer's behavior. This paper proposes a model by considering two types of spikes. Warranty claim data is analyzed with the proposed model. To represent spikes observed on the early warranty period, we classify failures into manufacturing-related failures and usage-related failures. Uniform distribution is assumed for the time delayed to diagnose and report by customers. By reducing maximum value of the delayed time by customers, the proposed model characterizes customer's rush in the vicinity of the warranty expiration limit. Experimental results by using the real warranty claim data show that the proposed model is better than the existing one in respect to MSE(Mean Squared Error). Moreover it is expected to estimate the failure rate more realistically with proposed model because it considers the delayed time to diagnose and report by customers.

• Journal of Chest Surgery
• /
• v.19 no.4
• /
• pp.744-749
• /
• 1986

Even in the hands of the expert endoscopists, an occasional instrumental perforation of the esophagus occurs. But instrumental perforation of the esophagus should not be difficult to diagnose if the possibility is borne in mind. Occasionally patient with esophageal perforations show little reaction at first, but usually they develop systemic manifestation if surgical management is delayed. Early surgical drainage of esophageal perforation is very important & effective therapeutic method. The delayed surgical treatment of esophageal perforation would have increased the morbidity & mortality by allowing mediastinitis & empyema thoracis. We have experienced 6 cases of delayed surgical management of instrumental perforation of esophagus from May 1974 to April 1986 in the department of thoracic and cardiovascular surgery, Yonsei University, college of the medicine. The ages ranged from 4 years to 57 years. The underlying esophageal diseases consisted of esophageal stricture in 3 cases, foreign bodies in the esophagus in 2 cases and esophageal ca. in one case. Most clinical manifestations on admission were high fever, chest discomfort, chest pain, dysphagia and subcutaneous emphysema. Most complications due to esophageal rupture were acute mediastinitis with or without empyema thoracis. Failure to diagnose promptly and failure to promptly institute adequate treatment undoubtedly were largely responsible for this patients death. All 6 patients had been taken delayed surgical drainage more than 24 hours following esophageal perforation. One patient had been in the open drainage state for long time and the another patient has been in the tracheostomy with postintubation vocal cord ulceration. The third patient died due to respiratory failure and sepsis due to fulminant mediastinitis & empyema thoracis. Even if the patients with esophageal perforation have been taken delayed surgical management, the patients should be survived with aggressive & effective surgical drainage with intensive post-operative care.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 1997.03a
• /
• pp.265-272
• /
• 1997

In this paper the bending collapse characteristics of 60 series Al rectangular tubes were studied with a pure bending collapse test rig which could apply the pure bending moment, there occured three kinds of bending collapse modes - local buckling, delayed buckling, tensile failure - depending on the b/t(width/thickness) ratio and material properties. Experiment results are compared with the results of finite element method.

• Clinical and Experimental Pediatrics
• /
• v.55 no.10
• /
• pp.393-396
• /
• 2012

Trisomy 14 mosaicism is a rare chromosome disorder characterized by delayed development, failure to thrive, and facial dysmorphism. Only approximately 30 trisomy 14 mosaicism cases have been reported in the literature because trisomy 14 is associated with early spontaneous abortion. We report a case of a 17-month-old girl with abnormal skin pigmentation, delayed development, facial dysmorphism, and failure to thrive with the 47,XX,+14/46,XX chromosome complement.

• Journal of Chest Surgery
• /
• v.28 no.11
• /
• pp.977-982
• /
• 1995

Early repair of complex congenital heart malformation may lead to life-threatening respiratory and hemodynamic embarrassment on sternal closure. We performed delayed sternal closure in nine neonates to avoid a fatal outcome in these situations. Primary elective open sternum was used in 8 [66.7% and primary sternal closure in 4 [33.3% of the 12 patients studied. one patient with primary sternal closure underwent delayed sternal reopening in the intensive care unit. Of the 9 patients with open sternum, 2 patients died of low cardiac output and acute renal failure respectively before delayed sternal closure. 7 patients could undergo delayed sternal closures 3 days after initial operation. The mean age at open cardiac procedure was 14.3 days [range 3 to 30 and mean preoperative weight was 3.4kg [range 2.8 to 4.1 . The aortic cross-clamping time was longer in the group with open sternum than the group with closed sternum [p=0.042 . There was no morbidity and mortality related to delayed sternal closure. Given the low morbidity and potential benifits, this technique should be used in neonates after open heart procedures when postoperative mediastinal compression produces frank low cardiac output or respiratoy compromise during a trial of sternal closure.

• Journal of Applied Reliability
• /
• v.15 no.4
• /
• pp.256-261
• /
• 2015

The aim of this paper is to present some issues to be discussed in relation to failure rate of a system that has identical parallel units. It is assumed that Time-to-Failure of each unit has the same exponential distribution and all units are repairable with a periodic maintenance of time interval T. Effective failure rate is widely recommended for nonrepairable systems as the reciprocal of MTTF but it should not be applied for repairable systems if delayed maintenance is used. And equivalent failure rate of an imaginary system is taken into consideration, the reliability value of which is the same as that of the redundant system when time interval T is given. With a numerical example, failure rate, effective failure rate, and equivalent failure rate of the redundant system are analyzed comparatively.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.26 no.11
• /
• pp.2305-2311
• /
• 2002

The pressure tube is a major component of the CANDU reactor, which supports nuclear fuel bundle and heavy water coolant. Pressure tubes are installed horizontally inside the reactor and only selected samples are periodically examined during in-service inspection. In this respect, a probabilistic safety assessment method is more appropriate fur the assessment of overall pressure tube safety. The failure behavior of CANDU pressure tubes, however, is governed by delayed hydride cracking which is the major difference from pipings and reactor pressure vessels. Since the delayed hydride cracking has more widely distributed governing parameters, it is impossible to apply a general PFM methodology directly. In this paper, a PFM methodology for the safety assessment of CANDU pressure tubes is introduced by applying Monte Carlo simulation in determining failure probability Initial hydrogen concentration, flaw shape and depth, axial and radial crack growth rate and fracture toughness were considered as probabilistic variables. Parametric study has been done under the base of pressure tube dimension and hydride precipitation temperature in calculating failure probability. Unstable fracture and plastic collapse are used for the failure assessment. The estimated failure probability showed about three-order difference with changing dimensions of pressure tube.

• Journal of Korea Society of Digital Industry and Information Management
• /
• v.8 no.4
• /
• pp.25-34
• /
• 2012

In this study, in the process of testing before the release of the software products designed, software testing manager in advance should be aware of the testing-information. Therefore, the effective learning effects perspective has been studied using the NHPP software. The finite failure nonhomogeneous Poisson process models presented and applied property of learning effect based on truncated time and delayed S-shaped software reliability. Software error detection techniques known in advance, but influencing factors for considering the errors found automatically and learning factors, by prior experience, to find precisely the error factor setting up the testing manager are presented comparing the problem. As a result, the learning factor is greater than autonomous errors-detected factor that is generally efficient model can be confirmed. This paper, a failure data analysis was performed, using time between failures, according to the small sample and large sample sizes. The parameter estimation was carried out using maximum likelihood estimation method. Model selection was performed using the mean square error and coefficient of determination, after the data efficiency from the data through trend analysis was performed.

• Journal of Electrical Engineering and Technology
• /
• v.13 no.1
• /
• pp.60-67
• /
• 2018

The presence of induction motor loads in a power system may cause the phenomenon of delayed voltage recovery after the occurrence of a severe fault. A high proportion of induction motor loads in the power system can be a significant influence on the voltage stability of the system. This problem referred to as FIDVR(Fault Induced Delayed Voltage Recovery) is commonly caused by stall of small HVAC unit(Heating, Ventilation, and Air Conditioner) after transmission or distribution system failure. This delayed voltage recovery arises from the dynamic characteristics associated with the kinetic energy of the induction motor load. This paper proposes the UVLS (Under Voltage Load Shedding) control strategy for dealing with FIDVR. UVLS based schemes prevent voltage instability by shedding the load and can help avoid major economic losses due to wide-ranging cascading outages. This paper review recent topic about under voltage load shedding and compare decentralized load shedding scheme with conventional load shedding scheme. The load shedding strategy is applied to an actual system in order to verify the proposed FIDVR mitigation solution. Simulations demonstrate the effectiveness of the proposed method in resolving the problem of delayed voltage recovery in the Korean Power System.

• Journal of Welding and Joining
• /
• v.5 no.2
• /
• pp.53-59
• /
• 1987

The effect of applied stress, current density and heat-treatment after welding on the time to fracture, fracture behavior was investigated by the method of constant load tensile testing under catholic charging with hydrogen in E.B. welded 250,300 Grade 18% Ni Maraging steel sheet. The main results obtained are as follows: 1. All specimen showed the characteristic delayed failure and the time to fracture showed decreasing tendency with the increase in current density and applied stress. 2. Hydrogen embitterment susceptibility of notched specimen after solution-treatment and aging after welding was more increased than that of aged smooth specimen and as welded specimen. 3. Fracture surface showed a typical intergranular fracture on the border, a dimple pattern in the center of specimen and some quasi-cleavage fracture between the intergranular and the dimple.