• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.60 no.6
• /
• pp.1274-1279
• /
• 2011

The purpose of this paper is to present the manufacturing defect and damage pattern of a 3 phase 22.9/3.3kV oil immersed transformer, as well as to present an objective basis for the prevention of a similar accident and to secure data for the settlement of PL related disputes. It was found that in order to prevent the occurrence of accidents to transformers, insulating oil analysis, thermal image measurement, and corona discharge diagnosis, etc., were performed by establishing relevant regulation. The result of analysis performed on the external appearance of a transformer to which an accident occurred, the internal insulation resistance and protection system, etc., showed that most of the analysis items were judged to be acceptable. However, it was found that the insulation characteristics between the primary winding and the enclosure, those between the ground and the secondary winding, and those between the primary and secondary windings were inappropriate due to an insulating oil leak caused by damage to the pressure relief valve. From the analysis of the acidity values measured over the past 5 years, it is thought that an increase in carbon dioxide (CO2) caused an increase in the temperature inside the transformer and the increase in the ethylene gas increased the possibility of ignition. Even though 17 years have passed since the transformer was installed, it was found that the system's design, manufacture, maintenance and management have been performed well and the insulating paper was in good condition, and that there was no trace of public access or vandalism. However, in the case of transformers to which accidents have occurred, a melted area between the upper and the intermediate bobbins of the W-phase secondary winding as well as between its intermediate and lower bobbins. It can be seen that a V-pattern was formed at the carbonized area of the transformer and that the depth of the carbonization is deeper at the upper side than the lower side. In addition, it was found that physical bending and deformation occurred inside the secondary winding due to non-uniform pressure while performing transformer winding work. Therefore, since it is obvious that the accident occurred due to a manufacturing defect (winding work defect), it is thought that the manufacturer of the transformer is responsible for the accident and that it is lawful for the manufacture to investigate and prove the concrete cause of the accident according to the Product Liability Law (PLL).

• Journal of the Korea Institute of Building Construction
• /
• v.1 no.2
• /
• pp.185-190
• /
• 2001

The purpose of this study is the development of practical Dry floor tile unit method that settle the defect of a wet method and designed for resin mat. With use of PE resin which is confirmed the basic property, it is developed that resin mat, joint-sealing compound with fixed form and space management to Dry floor tile unit method. The result of this study is below. 1) To acquire above the 4kgf/$\textrm{cm}^2$ - construction specification criterion, the bonding space that between resin mat and tile has to occupy the 50% of resin mat module space(10,000$\textrm{cm}^2$). 2) Criteria of bonding part plane is below. simpleness of metal form. productivity, uniform quality after injection molding cooling, easy cutting for remain space management, adhesive property, construction ability, transformation of a severed piece under pressure and so on. 3) To get the shape that could protect the interfacial breakdown, it is designed that resin mat and tile are unified after the bond input. 4) Adapted joint-sealing compound is the material of urethane kinds wedge form. Resin mat has the water passageway that could drain the water. 5) To manage the severed piece of tile, the resin mat is likely to divide the half and the quarter and the plastic drainage is developed in the severed piece.

• THE INTERNATIONAL COMMERCE & LAW REVIEW
• /
• v.27
• /
• pp.129-161
• /
• 2005

Todays, computers in business world are potent facilitators that most companies could not without them, while they are only tools. They offer extremely efficient means of communication, particularly when connected to Internet. What I stress in this article is the risks accompanied by e-commerce rather than the advantages of Internet or e-commerce. The management of e-commerce companies, therefore, should keep in mind that the benefit of e-commerce through the Internet are accompanied by enhanced and new risks, cyber risks or e-commerce risks. For example, companies are exposed to computer system breakdown and business interruption risks owing to traditional and physical risks such as theft and fire etc, computer programming errors and defect softwares and outsider's attack such as hacking and virus. E-commerce companies are also exposed to tort liabilities owing to defamation, the infringement of intellectual property such as copyright, trademark and patent right, negligent misrepresent and breach of confidential information or privacy infringement. In this article, I would like to suggest e-commerce insurance or cyber liability insurance as a means of risk management rather than some technical devices, because there is not technically perfect defence against cyber risks. But e-commerce insurance has some gaps between risks confronted by companies and coverage needed by them, because it is at most 6 or 7 years since it has been introduced to market. Nevertheless, in my opinion, e-commerce insurance has offered the most perfect defence against cyber risks to e-commerce companies up to now.

• International Commerce and Information Review
• /
• v.7 no.3
• /
• pp.27-51
• /
• 2005

Todays, computers in business world are potent facilitators that most companies could not without them, while they are only tools. They offer extremely efficient means of communication, particularly when connected to Internet. What I stress in this article is the risks accompanied by e-commerce rather than the advantages of Internet or e-commerce. The management of e-commerce companies, therefore, should keep in mind that the benefit of e-commerce through the Internet are accompanied by enhanced and new risks, cyber risks or e-commerce risks. For example, companies are exposed to computer system breakdown and business interruption risks owing to traditional and physical risks such as theft and fire etc, computer programming errors and defect softwares and outsider's attack such as hacking and virus. E-commerce companies are also exposed to tort liabilities owing to defamation, the infringement of intellectual property such as copyright, trademark and patent right, negligent misrepresent and breach of confidential information or privacy infringement. In this article, I would like to suggest e-commerce insurance or cyber liability insurance as a means of risk management rather than some technical devices, because there is not technically perfect defence against cyber risks. But e-commerce insurance has some gaps between risks confronted by companies and coverage needed by them, because it is at most 6 or 7 years since it has been introduced to market. Nevertheless, in my opinion, e-commerce insurance has offered the most perfect defence against cyber risks to e-commerce companies up to now.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.27 no.10C
• /
• pp.887-901
• /
• 2002

Software management model divided into the software project model and design estimation model, software matrices model, reliability growth model, process improvement model(or process maturity model) etc. Among these software management models, software complexity model make an estimated of the product software. For a practice of software managed, need to guideline of the static analysis of software. Especially, Software complexity model introduced for the estimation of software quantity and program complexity. In case of measurement the software matrices, its need for us to analysis of software quality and products. On the other hand, we known that complexity program include many defects and consuming of source cost. So, we apply to complexity model using of the program complexity, control structure and volume matrices, interface metrics, process complexity metrics method. In this paper, we represent that the analysis of fault data detected during the system test. Also, we analysis of program control structure and interface, volume matrices in various aspect of switching software. Others, their results utilized similar of project and system development.

• Journal of the Society of Disaster Information
• /
• v.8 no.1
• /
• pp.93-99
• /
• 2012

This study is to present false alarm management of alarm monitoring service, by literature analysis and interview with the persons in charge of service of alarm monitoring service companies. To reduce false alarm by customer's mistake, development of educational tool that could provide practical effect is needed. Also institutional consent to charge a specific sum of money could be considered for unnecessary dispatch that occurred by customer's mistake. To improve the false alarm by defect of equipments and installation of electronic security system, standardization of technical regulation and system installation is necessary. And to improve the performance of passive infrared sensor that cause most false alarm, the development of new type of sensor is required. It could be considered that guideline on educational contents and term definition about false alarm could be come under the security regulation.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.47 no.3
• /
• pp.248-256
• /
• 2011

The inherent efficiency of a ship would be prior to any other quality factors in ship's safety, because lack of it may give rise to a serious sea casuality even if it were a light mistake in operation. And the representative casualty comes from a deficiency of stability and an operating error combined would be capsizing. The Korean offshore large purseiner looks to have a structural weak point with small range of stability in spite of her big initial metacentric height, and have various type of roll reduction devices in order to cover up the defect. The aim of this study is to grasp for the roll reduction characteristics of the purseiner with bilge keel only and a stern keel additionally attached. The results are summarized as follows; The rolling angle of the model ship was increased in accordance with increase of the wave period and height, especially at close to the natural wave period of her, and the trends were more distinguished in the situation of bilge keel only installation than in the stern keel additionally installed. And stern keel has not noticeable effect on the reduction of the roll in the light ship condition, but has a little effect in full load condition.

• Korean Journal of Construction Engineering and Management
• /
• v.12 no.6
• /
• pp.42-53
• /
• 2011

This study is to present a method of compiling consistently accurate construction cost estimates in minimum of time. There are two kind of applications for estimating system based on quantity-per-unit and the daily work-crew. The former system is still applied 45% as a estimating method to construction job site by the second half of 2010. However, it is necessary for quantity-per-unit to complement the defect of standard integrating specification and improve the integrating method to the various construction conditions. The later system is intended to represent a standard or basic core which can be adopted in many type of construction estimating used across the wide variety of construction in advanced countries. In this study daily work-crew based on productivity is applied to the representative B.O.Q Item in road project. These results are compared to productivity of Japan and U.S.A estimated under the similar circumstances.

• Industry Promotion Research
• /
• v.1 no.2
• /
• pp.49-54
• /
• 2016

This study analyzed the effect of small manufacturing firms' systematic documentation on productivity. The study results showed that establishment of work system documentation significanlty affectd defect decrease(p<.05) and production efficiency(p<.01), but ducumentation experience didn't significantly affected productivity improvement. So, it is suggested that firms should establish documentated work system and conduct education & training rather than depending on experiential aspect to improve productivity. This study provided implications for checking importance of documentation factor on productivity improvement and verifying the effect of documentation in quality management aspect.

• Journal of Korean Society for Quality Management
• /
• v.49 no.4
• /
• pp.581-594
• /
• 2021

Purpose: The purpose of this study is to compare machine learning models for anomaly detection of mechanical facility equipment and suggest an anomaly detection system for mechanical facility equipment in subway stations. It helps to predict failures and plan the maintenance of facility. Ultimately it aims to improve the quality of facility equipment. Methods: The data collected from Daejeon Metropolitan Rapid Transit Corporation was used in this experiment. The experiment was performed using Python, Scikit-learn, tensorflow 2.0 for preprocessing and machine learning. Also it was conducted in two failure states of the equipment. We compared and analyzed five unsupervised machine learning models focused on model Long Short-Term Memory Variational Autoencoder(LSTM-VAE). Results: In both experiments, change in vibration and current data was observed when there is a defect. When the rotating body failure was happened, the magnitude of vibration has increased but current has decreased. In situation of axis alignment failure, both of vibration and current have increased. In addition, model LSTM-VAE showed superior accuracy than the other four base-line models. Conclusion: According to the results, model LSTM-VAE showed outstanding performance with more than 97% of accuracy in the experiments. Thus, the quality of mechanical facility equipment will be improved if the proposed anomaly detection system is established with this model used.