• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2004.09a
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• pp.93-99
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• 2004

At present, LG Electronics pushes ahead to eliminate the Pb(Lead) -a hazardous material- from all products. Especially, we have performed to select the optimum standard composition of lead free alloy for the application to products for about 3 years from 2000. These days, we have the chance for applying to the mass-production. This project constructed the system for applying the lead free solders on consumer electronic products, which is one of the major products of the LG Electronics. To select the lead free solders with corresponding to the product features, we have passed through the test and applied with Sn-3.0Ag-0.5Cu alloy system to our products, and for the application to the high melting temperature composition, we secured the thermal resistance of the many parts and substrate and optimized the processing conditions. We have operated the temperature cycling test and the high temperature storage test under the standards to confirm the reliability of the products. On these samples, we considered the consequence of our decision by the operating test. For the long life time of the product, we have operated the temperature cycling test at $-45^{\circ}C-+125^{\circ}C$, 1 cycle/hour, 1000 cycles. Also we have tested the tin whisker growth about lead free plating on lead finish. We have analyzed with the SEM, EDS and any other equipment for confirming the failure mode at the joint and the tin whisker growth on lead free finish.

• Journal of international Conference on Electrical Machines and Systems
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• v.3 no.2
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• pp.190-199
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• 2014

In the last years, fault problem in power electronics has been more and more investigated both from theoretical and practical point of view. The fault problem can cause equipment failure, data and economical losses. And the analyze system require to ensure fault problem and also rectify failures. The current errors on these faults are applied for identified type of faults. This paper presents technique to detection and identification faults in three-phase voltage source inverter (VSI) by using time-frequency distribution (TFD). TFD capable represent time frequency representation (TFR) in temporal and spectral information. Based on TFR, signal parameters are calculated such as instantaneous average current, instantaneous root mean square current, instantaneous fundamental root mean square current and, instantaneous total current waveform distortion. From on results, the detection of VSI faults could be determined based on characteristic of parameter estimation. And also concluded that the fault detection is capable of identifying the type of inverter fault and can reduce cost maintenance.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.9
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• pp.117-123
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• 2009

Recently, the failures of electrical equipment have been reduced due to the improvement of its quality and the advance of operation techniques but the failure rates caused by natural disasters such as wind and lightning have been increased. To reduce the failures due to lightning, it is necessary for insulation design of transmission lines to be done, effectively. Also the analysis on the lightning characteristics is essential to the effective insulation design. In this paper, we describe lightning distribution, multiplicity, IKL(Iso-Keraunic Level) and amplitude distribution of lightning current base on the lightning data by KLDNet.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.54 no.9
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• pp.449-456
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• 2005

The preventive diagnostic technique prevents transformers from power failure through giving alarm and observing transformers in service. And it helps to establish the plan for optimum maintenance of the transformer as well as to find location or cause of fault using accumulated data. Data detection and experience of the preventive diagnostic system need to establish the preventive diagnostic algorithm regarding interrelationship between detected data and deterioration of equipment. Therefore in-depth analysis about the preventive diagnosis system is required. KEPCO has adopted the preventive diagnostic system at nine 345kV substations since 1997. Techniques for component sensors of the preventive diagnosis system were settled but diagnosis algorithm, diagnostic criteria and practical use of accumulated data are not yet established. This paper, to build up the base of preventive diagnostic algorithm for the Power transformer. investigated the preventive diagnostic criteria for the power transformer.

• Journal of Energy Engineering
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• v.21 no.1
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• pp.75-80
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• 2012

In this paper a realistic bounding method for flooding analysis following rupture of large size of thanks and piping is defined. Mass and energy release during main feedwater line break accident is analyzed with RETRAN code. It is modeled that the main feed water control valve is closed in 5.0 seconds after reactor trip. In result of the analysis, largest mass and energy is discharged at 70% reactor power. The flood sources for main feedwater room are calculated when piping failure occurs in the high energy line and medium energy line. Based on the result of flood level (1.43m), it is investigated that all of the safety-related environmental qualification equipments are well located above the flood level.

• Journal of Korean Society for Quality Management
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• v.21 no.2
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• pp.1-16
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• 1993

Early generations of products had little to no inherent capability to test themselves. The technologies involved often required only visual inspection and limited probing to troubleshoot the system once it was turned over to maintenance personnel. However, as the complexity of military and commercial systems grew, symptoms of failure became less noticeable to the operator. Therefore, the procedure to access, inspect, repair and replace a component became complicated, the requirements for personnel skill and testing equipment increased. and it took too long of a time to maintain a system. Meanwhile, the need for availability became more mission-critical and maintenance become very expensive. The obvious solution was to design in-system circuits or devices to self-test the primary system, the Built-In-Test(BIT) was born. This approach has continued right on up through present systems and is an integral part of systems now being designed. The object of this paper is to present a state-of-the-art research for filtering out the BIT diagnosis mistakes using Bayesian analysis and develop the algorithm for Redundant systems with BIT to improve BIT diagnosis.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.9
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• pp.1054-1061
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• 2011

GMA welding process is a production process to improve productivity for the provision of higher quality of material, These includs numerous process variables that could affect welding quality, productivity and cost savings. Recently, the welding part of construction equipment had frequent failure of major components in the welding part of each subsidiary material due to shock which is very poor according to the welding part. Therefore, the implementation of sound welding procedure is the most decisive factor for the reliability of construction machinery. The data generated through experimens conducted in this study has validated its effectiveness for the optimization of bead geometry and process variables is presented. The criteria to control the process parameters, to achieve a healthy bead geometry. This study has developed mathematical models and algorithms to predict or control the bead geometry in GMA fillet welding process.

• The Korean Journal of Pain
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• v.12 no.2
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• pp.268-271
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• 1999

Intrathecal phenol-glycerin block is a potent tool in stepwise approach to intractable perineal pain. At outpatient clinic, intrathecal phenol-glycerin block have been frequently used to control the cancer pain, as this procedure does not require special equipment. However, undesirable effects may occur with any given intrathecal injection. Although most side effects do not last long, they deserve well to prevent. Recently, we have been controlled the perineal and perianal cancer pain with intrathecal phenol-glycerin block without any specific complications. However, one patient we managed experienced that one patient, with this procedure for chronic non-malignant perineal pain control experience gait disturbance and one-week of voiding and defication difficulties. This research reports these practices, including the review of literature.

• Journal of the Korean Society of Safety
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• v.28 no.5
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• pp.27-34
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• 2013

Almost accidents in construction sites are occurred by unsafe work conditions and failure making safe environment. As recent construction projects become more complex, various and diversified, So the potential of construction-related accidents is increased as well. Comparing the frequency of construction-related accidents in large-sized construction sites, small-sized construction sites are more vulnerable because of lack of workforce and less effective technology system. Furthermore, the absence of safety committee, poor financial condition leads to lack of safety education, installation of safety facilities, and provision of individual protective equipment, which indicates difficulties handling even basic safety management. Therefore, in order to lower the hazard rate at small-Sized construction sites, it is necessary to proceed with more structural and thorough actions for preventing accidents. In other words, it is necessary to analyze the causes of the accidents at small-sized construction sites, set criteria for safety management, and suggest safety management items according to work classification by evaluating the relative importance of the items.

• International Journal of Safety
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• v.4 no.2
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• pp.18-23
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• 2005

There are many electrical connections in the electric apparatus and most fires due to a fault contact result from a failure or misuse of electric apparatus and installation. The fault contact happens between electrical connections by the loose and the mechanical vibration. In this paper, we have investigated thermal and electrical properties of screwed electric contacts due to the mechanical vibration. The exciter was connected to a signal generator and power amplifier that provided the vibration frequency and amplitude. The vibration, temperature and voltage data were sent to a data acquisition system (DAQ). In the case that fault contact took place, the arc happened between the screwed electric contact and electric wire, heat due to the arc was transmitted to the adjacent insulators, for which the oxide could be generated more. In addition, a spark was generated and the insulator began to melt. Thus, the possibility of electrical fire became the highest in this case. Finally, when the fault contact takes place due to vibration, the hazard of an electric accident is very high.