• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2023.05a
• /
• pp.337-338
• /
• 2023

As the number of defects in apartments has increased recently, lawsuits and disputes related to defects have also increased. As a result, the loss of time and money is enormous. Therefore, fundamental measures are needed to reduce the occurrence of defects. Therefore, the purpose of this study is to propose a plan to reduce defects, focusing on window construction. To this end, existing studies were reviewed, and data from domestic construction companies were collected and classified to organize the types of defects. Based on the classified data, eight types with a high incidence of window glass were analyzed according to the time of occurrence, and the cause and causal relationship of the defect were schematized. It aims to identify the degree of possibility of recurrence of defects for each of the eight defect types for experts and derive key management elements using the RII method. Therefore, the goal is to select key management elements of window construction that actively reflect the characteristics of the construction stage.

• International conference on construction engineering and project management
• /
• 2011.02a
• /
• pp.629-635
• /
• 2011

Retentions are generally considered to be intended to act as a powerful tool to incentivize contractors/subcontractors to remedy defective work in cases of non-performance. This study attempts to establish the extent to which retentions can be used for this purpose by investigating case law connected with insurance and defective work. One of the significant questions is whether retentions are sufficient to deal with construction defects or value of retentions in the rectification of defects is illusory. The cost to repair a defect may vary depending on a number of components including type, cause, magnitude and the construction stage at which the defect occurs. It is expected that a review of existing cases on defective workmanship will provide an insight on the issues and whether retentions are effective in their intended function. In order to establish their functionality, the study described in this paper investigated 6 construction insurance cases to identify the critical issues and the causes of dispute. It was found that the nature and the cause of defects were different in each case. It was also established that certain defect types not covered by insurance may be covered by retentions - potentially one of the key uses of a retention strategy. It is expected that the findings will assist in forming a view on the quantum of money that may be required paving the way for a first time understanding on a rational basis for setting up retention regime.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.33 no.2
• /
• pp.9-17
• /
• 2010

Complex products may present more than one type of defects and these defects are not always of equal severity. These defects are classified according to their seriousness and effect on product quality and performance. So, demerit systems are very effective systems to monitor the different types of defects. Recently, Kang et al.(2009) proposed the revised Demerit-CUSUM for the evaluation of the Demerit-CUSUM control chart performance exactly. In this paper, we present an advanced Demerit control chart using the double EWMA technique. The double EWMA technique is very efficient and strong method for process control where defects and nonconformities occur with various defect types. Moreover, we compare exact performance of Demerit-CUSUM, Demerit-EWMA and Demerit-DEWMA control chart according to changing sample size or mean shifts magnitude. By the result, we confirm that the performance of Demerit-DEWMA control chart is more than the performance of the Demerit-CUSUM and Demerit-EWMA control chart.

• Journal of Auto-vehicle Safety Association
• /
• v.7 no.4
• /
• pp.20-25
• /
• 2015

The basic point of a vehicle recall is to remove vehicle defects as soon as possible and thus prevent possible road traffic accidents caused by the defects beforehand. Therefore, the core of vehicle recall under the self-certification system consists of a timely response and fast remedy of defects. The present study aimed to deduce a plan for improvement of the system necessary for the fast remedy of defects through a phased analysis of defect investigation procedure based on defect investigation statistical data. There will be a need to make the TSB(Technical Service Bulletin) or service campaign data submission of a manufacturer compulsory for the collection of broad defect information in the stage of information analysis and to impose a higher penalty when the manufacturer violates the data submission in the investigation stage. In addition, it is considered that an active service campaign should be induced and a punishment for late recall will be needed for consumer protection.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
• /
• v.34 no.4
• /
• pp.428-434
• /
• 2008

Introduction: Piezosurgery device is one of the most commonly used instrument on the intraoral surgery such as maxillary sinus lift and autogeneous bone graft. Piezosurgery instrument also contains the tips that are manufactured especially for the convenient bone graft, which now many surgeons apply them for collecting bone graft materials in the curettage method for the restoration of skull defects. However, objective data has not been shown concerning the effects about bone graft with using Piezosurgery. Therefore we investigated the effects of Piezosurgery on the rabbit-skull defect healing. Materials & Methods: To investigate the regeneration of the bony defect with various bone graft, 10 adult New Zealand white rabbits (average weight : $2.8{\pm}0.3kg$, about 12weeks) were used. The four circular bony defects measuring 6mm in diameter were made with Piezosurgery device on each rabbit cranial bone. The harvested bone tissues during defect formation were also used for autogeneous bone graft. They were grafted into the defects in a various type; block type (Group 1), particulated type by the bone mill (Group 2), chopped type by curette shaped Piezosurgery tip (Group 3), the defect without any graft was served as control (control group). The animals were sacrificed after 6 weeks and bone regeneration capacity was evaluated histomorphometrically. Result & Conclusion: Autogeneous bone graft harvested using a Piezosurgery instrument showed satisfactory bone regeneration. There was no conspicuous difference bone prepared among by bone mill or Piezosurgery and block bone graft. Therefore, the bone harvested from the intraoral site near the operation field using the piezosurgery device can be a feasible and reliable graft for intraoral bony defects.

• Proceedings of the KSR Conference
• /
• 1998.11a
• /
• pp.87-95
• /
• 1998

This study proposes the analysis and evaluation method of time series ultrasonic signal using the attractor analysis. Features extracted from time series signal analyze quantitatively characteristics of welding defects. For this purpose, analysis objective in this study is fractal dimension and attractor Quadrant feature. Trajectory changes in the attractor indicated that even the same type of defects carried substantial difference in fractal characteristics resulting from distance shifts such as parts of head and flange. Such differences in characteristics of weld defects enables the evaluation of unique features of defects in the weld zone. In quantitative fractal feature extraction, feature values of 3.848 in the case of part of head(crack) and 4.102 in the case of part of web(side hale) and 3.711 in the case of part of flange(crack) were proposed on the basis of fractal dimensions. Proposed attractor feature extraction in this study can enhance the precision rate of ultrasonic evalaution for defect signals of rail weld zone such as side hole and crack.

• Journal of the Korean Society for Nondestructive Testing
• /
• v.9 no.1
• /
• pp.8-21
• /
• 1989

This paper presents the ultrasonic characteristics of weldment and detectability of defects of weldment in Austenitic Stainless Steel Type 304 that is composed of mostly coolant piping system in nuclear power plants. The results of this experient show as follows: 1. When the ultrasonic beam detects the defects on the side of base metal and on the opposite side of weldment, the indications which was detected on the screen show different amplitude and different metal path each. 2. The ultrasonically estimated notch depth is generally oversized than actual notch depth. 3. It is easy for the false indication to show up on the screen because of columnar structure of weldment in austenitic stainless steel. 4. The higher frequencies of transducer have more difficulties to detect the defects of the opposite side of weldment because of ultrasonic attenuation in weldment and the longitudinal transmitter-receiver transducer is the most effective in detecting the opposite side defects of weldment.

• Journal of the Korean Society of Safety
• /
• v.20 no.1 s.69
• /
• pp.30-35
• /
• 2005

This study proposes construction of through transmission for weld defects detection of rail weld zone from ultrasonic signals. For these purposes, the ultrasonic signals for defects(porosity and crack) of weld zone in rails are acquired in the type of time series data and echo strength. 6 lines in the distance amplitude characteristics curve(DACC) indicated damage evaluation standard of weld zone in rails. The acquired ultrasonic signals agree flirty well with the mesured results of reference block and sensitivity block(defect location beam propagation distance, echo strength, etc). The proposed construction of through transmission in this study can be used for weld defects detection of rail weld zone.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.20 no.9
• /
• pp.780-786
• /
• 2007

This paper describes the influence on partial discharge characteristics of defects at the model XLPE/EPDM interfaces of power cable joints. The defects of void and copper which could inadvertently be present at the joint interface. We measured ${\Phi}-n,\;{\Phi}-q$ patterns by a computer-aided partial discharge measuring system. Several parameters i, e, maximum discharge $q_{max}$ [pC], average discharge q [pC/cycle], and average angle of discharge ${\Theta}g$ [deg] were found to depend upon the defect type varying applied voltage. As the result of time evaluation, partial discharges are small different at copper defects, but is decreasing obviously about 20 minutes at void defect. It considered that difference of magnitude of total positive discharge of Q+ [pC] and total negative discharge of Q- [pC] is SPMD(swarming pulsive micro discharges).

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2022.04a
• /
• pp.29-30
• /
• 2022

Tile defects in apartment houses are caused by a combination of various factors. These factors cannot be specified, and it is difficult to determine the exact cause because a number of causes are intertwined. In addition, because the climate of Korea is different by season, the coefficient of thermal expansion between materials is different, which is a major cause of tile defects. Therefore, this study analyzed the difference between the construction location and the period of defect occurrence according to the types of tile defects caused by environmental differences between indoor and outdoor environments. Two-way ANOVA was used, indoor and outdoor spaces were selected, and defect types were selected accordingly to show the difference in the occurrence period of each defect.