• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.10a
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• pp.257-261
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• 2011

The failures of local structure of marine medium-speed diesel engine occurred in durability test. The vibration response of the whole engine was in an acceptance level, but the local structures were broken. ODS test and vibration measurement were carried out in order to investigate the root cause of durability problem. These tests revealed that the root cause of failures was excessive vibration by $4.5^{th}$ resonance between engine body and local structure. The best solution to reduce the vibration response is to change the type of mount. After a rigid mount was replaced by a flexible mount, maximum vibration level dropped to 72%.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.1306-1311
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• 2006

The root cause of abnormal sound from a heat exchanger of condensate water system in a nuclear power plant is investigated by using the impact signal-processing methodology based on the Hertz theory. The predicted results for the location of impact force and the loose part size meet good agreement with the identified materials during the overhaul period in the plant. Nuclear power plants have experienced several loose parts and the frequency of the loose part will be increased along the aging of the plants. So, this analysis methodology for the impact signal will be widely utilized for the primary and secondary side of the nuclear power plant.

• ETRI Journal
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• v.36 no.6
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• pp.1023-1031
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• 2014

Failure analysis is necessary to clarify the root cause of a failure, predict the next time a failure may occur, and improve the performance and reliability of a system. However, it is not an easy task to analyze and interpret failure data, especially for complex systems. Usually, these data are represented using many attributes, and sometimes they are inconsistent and ambiguous. In this paper, we present a scalable approach for the analysis and interpretation of failure data of high-performance computing systems. The approach employs rough sets theory (RST) for this task. The application of RST to a large publicly available set of failure data highlights the main attributes responsible for the root cause of a failure. In addition, it is used to analyze other failure characteristics, such as time between failures, repair times, workload running on a failed node, and failure category. Experimental results show the scalability of the presented approach and its ability to reveal dependencies among different failure characteristics.

• Proceedings of the Korean Reliability Society Conference
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• 2005.06a
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• pp.199-208
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• 2005

In the calendar and the advertising catalog, the surface Is usually coated by coating polypropylene film. The delamination failure of coating film depends on surface roughness and quality of the substrate paper. In this paper, the mechanisms of delamination failure between the coating film and the paper is investigated by using the root cause analysis as one of techniques of reliability evaluation. The papers used in failure analysis are three kind products made by two domestic and one foreign companies. It found that the main causes of delamination failure between the coating film and the paper were the creation of microvoids caused by shape of filler and their growth caused by contraction of paper.

• Development and Reproduction
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• v.26 no.4
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• pp.183-190
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• 2022

Today's Eastern philosophers try to use the formal logic organized by Aristotle, saying that there was no logic in the East. This researcher found that Confucius and other Asians used Che-Yong logic. The Che-Yong logic is based on the Che-Yong law, which is a natural law. The Che-Yong law consists of the Che-Yong principle and the Hyeon-Mi principle. The Hyeon-Mi principle is that if there is an appearance on the outside, there is a corresponding cause in it. The Che-Yong principle is that the highest common cause of various appearances is Che, and the Che grows and changes on its own to become a Yong. Identifying Che and predicting Yong is Che-Yong logic. Here, I'd like to introduce Che-Yong logic and suggest a new research methodology to apply it.

• International conference on construction engineering and project management
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• 2015.10a
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• pp.317-320
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• 2015

Documenting work-in-progress on construction sites using images captured with smartphones, point-and-shoot cameras, and Unmanned Aerial Vehicles (UAVs) has gained significant popularity among practitioners. The spatial and temporal density of these large-scale site image collections and the availability of 4D Building Information Models (BIM) provide a unique opportunity to develop BIM-driven visual analytics that can quickly and easily detect and visualize construction progress deviations. Building on these emerging sources of information this paper presents a pipeline for model-driven visual analytics of construction progress. It particularly focuses on the following key steps: 1) capturing, transferring, and storing images; 2) BIM-driven analytics to identify performance deviations, and 3) visualizations that enable root-cause assessments on performance deviations. The information requirements, and the challenges and opportunities for improvements in data collection, plan preparations, progress deviation analysis particularly under limited visibility, and transforming identified deviations into performance metrics to enable root-cause assessments are discussed using several real world case studies.

• The Journal of the Korean dental association
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• v.14 no.5
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• pp.457-459
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• 1976

The author experienced a failed ase of root resection which qas performed on the abnormal upper right lateral incisor. The patient was 16year old female. Clinically the effected tooth had neither a carious cavity nor periondontal diseases, ut, a fistula was present on the gum tissue near the root apex. The roentogenogram revealed a pathological area around the apex of the tooth. The results of failed apicoectomy lead to following conclusions. 1. The operated tooth was a case of dense invaginatus which had two pulp cavities and two canals seperated along their entire length. 2. It was the main cause of failure that the second pulp cavity and root canal were not obturated.

• The Journal of the Korean dental association
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• v.52 no.2
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• pp.85-95
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• 2014

Completely avulsed tooth caused by a traumatic injury needs replantation for treatment choice. But, replantated tooth usually comes with inflammatory root resorption, replacement resorption and ankylosis, moreover ankylosis cause severe functional and esthetic problems. The outcome of replantated tooth depends on the following factors; minimal damage to pulp and periodontal tissue, the length of extraoral time, the medium of the tooth stored, the level of root formation and so on. The purpose of this case report is to describe the variable resorption pattern and to discuss types that influence the occurrence of resorption.

• Journal of Korean Dental Science
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• v.15 no.2
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• pp.147-151
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• 2022

Horizontal root fracture (HRF) is a result of trauma to teeth and periodontium, which implies severe injury to cementum, dentin, and pulp. This is a rare case of HRF in the maxillary lateral incisor of a 62-year-old male who only presented persistent gingival swelling, fistula, and dull pain at first. An apical radiolucency of unknown origin turned out to be a result of hidden HRF at the coronal third level that was later visualized radiographically during endodontic treatment. The tooth was scheduled to be extracted upon the patient's agreement. The purpose of this report is to alert clinicians about the importance of diagnosing HRF through thorough clinical and radiographic examinations. Where there is persistent fistula without proper cause, HRF should be considered as a causative factor, and the diagnosis could be effective with aid of cone beam computed tomography, electronic root apex locator, as well as other clinical signs.

• Journal of the Korean Society of Safety
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• v.35 no.5
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• pp.115-120
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• 2020

From 2009 when the CNS facility was installed, the number of reactor failures due to abnormal CNS facility system has increased significantly. Of the total of 19 nuclear reactor shutdowns over the six years from 2009 to 2019, there were 10 nuclear reactor shutdowns associated with the CNS facility, which are very numerous. Therefore, this report intends to analyze the history of nuclear reactor shutdowns due to CNS facility system failure in detail, and to present the root cause and solution to problems. As a result of FMEA implementation of CNS facility system, a total of 76 SPVs were selected. In addition, 10 cases of reactor shutdown history due to CNS facility system abnormalities were analyzed in detailed, and improvement plans for solving the root cause and problem were suggested for each trip history. The results of this study are expected to be able to operate the domestic research reactor and CNS facilities more stably by providing effective measures to prevent recurrence of CNS facilities and reactor trips.