• Proceedings of the KSR Conference
• /
• 2005.11a
• /
• pp.682-687
• /
• 2005

High quality power supplying of power distribution system in electric railway system is the important function. Power feeding system is complicated witch is compose with distribution line, circuit break, protection facilities and so on. Among this components, role of substation is most important for elevation of reliability in electric power system. Therefore, the enhanced reliability considering the preventive inspection, repair work, replacement is necessary. In this study, a proposed the enhanced reliability method through a calculation of fault probability in power feeding system.

• 대한공업교육학회지
• /
• v.38 no.1
• /
• pp.239-258
• /
• 2013

The purpose of this study is to define what circuit repairing ability is and to check improvement in learner's circuit repairing abilities by verifying conformity of learner's achievement of target goals that have been derived from headlight assignment based on circuit repairing ability that has been categorized into six sub-factors, which are preparing ability, attaching/detaching ability, circuit analyzing ability, inspecting and measuring ability, repairing (problem solving) ability and organizing ability. In order to achieve the purpose of study, degree of improvement in circuit repairing ability of learner's group was measured through experiment design and verification by group of experts. SPSS statistics program was used for statistical analysis in which average value for descriptive statistics, Cronbach ${\alpha}$ coefficient and t-test were conducted. Level of significance for t-test was p<.05. The conclusions from conducting this study are as follows. Firstly, the usage of terminology 'circuit repairing ability' pertaining to ability to repair failure of electrical devices in automobiles was confirmed to be appropriate. Secondly, the categorization of circuit repairing ability into sub-factors of preparing ability, attaching/detaching ability, circuit analyzing ability, inspecting and measuring ability, repairing (problem solving) ability and organizing ability was confirmed to be appropriate. Thirdly, field instruction on headlight assignment that has been revised according to achievement of learner's goals was confirmed to be effective in improving learner's circuit repairing abilities compared to regular training. Fourthly, field instruction on headlight assignment that has been revised according to achievement of learner's goals was confirmed to be effective in improving sub-factors of circuit repairing abilities, which are preparing ability, attaching/detaching ability, circuit analyzing ability, inspecting and measuring ability, repairing (problem solving) ability and organizing ability.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2016.10a
• /
• pp.101-104
• /
• 2016

In this study, we propose an algorithm to simulate the function of the coupling structure and having two neurons to find out exactly recover the temporary or permanent position errors that can occur during operation in a digital circuit was separated by function, a 3x3 array. If any particular part in the combined cells are differentiated cells have a problem that function to other cells caused an error and perform the same function are subjected to a step of apoptosis by the surrounding cells. Designed as a function block in the function and the internal structure having a cell structure of this digital circuit proposes an algorithm.

• Journal of Veterinary Clinics
• /
• v.29 no.5
• /
• pp.416-421
• /
• 2012

A 10-year-old 4-kg spayed female Chihuahua with severe congestive heart failure was referred for surgical treatment. Through several examinations, the dog was diagnosed as severe mitral regurgitation (MR) and moderate TR. Because of the poor prognosis associated with continuation of medical management, surgical repair of the mitral valve was considered as the treatment option for the dog. The mitral valve repair was performed undergoing cardio pulmonary bypass (CPB) circuit. However after mitral repair, the dog was died without recovery from anesthesia. Many risk factors associated with failure of cardiac surgery are included CPB management, hypothermia, organ dysfunction, hemorrhage, hypotension, electrolyte & acid base imbalance, and infection. Although the dog is died from the operation, it is an important to reveal the factors of failure in veterinary clinic. From the case report, causes of failure of mitral valve repair can be considered from the failure of oxygenation and gas exchange by hypothermia and serious hypotension with low heart rate by low cardiac output syndrome (LCOS). Through the several considerations from this case, it is known that coming cardiac surgery for mitral valve repair is required to be more careful for successful operation. Further it can be brought to increase success rate in further operation.

• Explosives and Blasting
• /
• v.17 no.4
• /
• pp.8-17
• /
• 1999

Unfortunately leaks occur in heat exchangers periodically, usually at the tube to tubeplate joint. The usual method of repair is to plug off the defective area and isolate the tubes of concern from the circuit. If the leaks continua the thermal capacity of the units is progressively reduced and for this reason the alternative of using an internal bridging sleeve has been examined. This paper discusses the overall development activities that has been found necessary to bring this repair procedure to a successful conclusion for use on the nuclear steam generator. In this work we have investigated optimum explosives and explosive quality, explosive sleeving's thickness, the design of sheath stress relieving heat treatment pull-out load, hydraulic leakage, stress corrosion cracking properties. The results obtain are as follows : (1) The optimum explosives and explosive qualities are PETN and about 15~40 gr/ft of explosive sleeving in nuclear steam generator. (2) Explosive sleeving's thickness is 1.1~l.4mm, If groove of 0.35mm formed in sleeve outside existed, For the hydraulic leakage is go up, explosive sleeving of formed groove are applicate tube and turnplate. (3) If the stress relieving heat treatment are experiment in $750^\circ{C}$, $850^\circ{C}$, 15 minutes Pull-out strength of sleeving 1,500~2,300kg, hydraulic leakage is $250kg/cm^2$.

• Nuclear Engineering and Technology
• /
• v.52 no.9
• /
• pp.1974-1982
• /
• 2020

Numerical prediction of fission product plateout and circulating coolant activities under normal operating conditions is crucial in the design of a high temperature gas-cooled reactor (HTGR). The results are used for the maintenance and repair of the components as well as the safety analysis regarding early source terms under loss of coolant accident scenarios. In this work, a new computer code named POSCA (Plate-Out Surface and Circulating Activities) was developed based on a one-dimensional model to evaluate fission product plateout and circulating coolant activities within the primary circuit of a HTGR. The verification and validation of study for the POSCA code was done using available analytical results and two in-pile experiments (i.e., OGL-1 and VAMPYR-1). The results of the POSCA calculations show that POSCA is able to simulate plateout and circulating coolant activities in a HTGR with fast computation and reasonable accuracy.

• Proceedings of the Korean Society of Marine Engineers Conference
• /
• 2006.06a
• /
• pp.271-272
• /
• 2006

Zinc confers high corrosion resistance by acting as a sacrificial anode, and a zinc coating improves the appearance of steel. Chromate conversion coating (CCC) films are still one of the most efficient surface treatments for steel. Although such films can self-repair via the dissolution of Cr(VI), dissolved Cr(VI) have adverse effects on humans, and the environment. Therefore, we examined the corrosion protection property and morphology of colloidal silica conversion films as an alternative to CCC films. The corrosion behavior was investigated in 3% NaCl solution using electrochemical techniques, including electrochemical impedance spectroscopy, open circuit potential, and the salt spray test(SST). Corrosion was implied by the appearance of red rust on the specimen surface. In corrosion resistance at 3% NaCl solution, red rust appeared at 15-20, 55-70, and 83-98 days on Zn-electroplated steel, colloidal silica conversion-coated specimens, and CCC-coated specimens, respectively. In the salt spray test, the colloidal silica film provided better corrosion protection than CCC films, i.e., red rust appeared at 96 hours on the Zn-electroplated steel sheet, at 432 hours with the CCC films, and at 888 hours with silica conversion coating.

• The Transactions of the Korean Institute of Electrical Engineers B
• /
• v.50 no.10
• /
• pp.483-493
• /
• 2001

The 3-phase induction is used for the MCP(main coolant pump) and the pure water is used for lubrication of bearing because of the difficulty of repair. Therefore the type of motor is the canned-motor that is welded by sealed can to prevent the stator and rotor from the lubricating water. A lot of Eddy currents are produced in the can because of the conductivity of material. And these eddy currents in the can are the most important cause that decrease the efficiency of induction motor. Therefore we have to find the method to decrease these eddy currents in the can for the improvement of efficiency of motor. In this paper, we proposed the method of design and analysis of canned-motor using equivalent circuit with consideration of can loss for the improvement of efficiency of motor.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.38B no.11
• /
• pp.902-910
• /
• 2013

The most representative research network in Korea, KREONET, has developed DynamicKL, an advance reservation based Network Service Agent (NSA) for user driven virtual circuit services. DynamicKL provides reservation, provisioning, release, termination, and inquiry web services for network resources by using an open standard network service interface (NSI), as well as web services for network resources by using a GUI interface. In addition, it has the RICE interface to support a protection management function per VC for virtual circuits and reservations. In this article, a protection management per VC for provisioned VCs and reservations is addressed in the DynamicKL framework, as a contribution to the VC protection management issue, which results in more manageable and reliable VC services compared to other advance reservation frameworks. An administrator can detect successful or unsuccessful VC protections in the event of a primary link failure and successful or unsuccessful VC retrievals after a primary link repair, by using RICE.

• Journal of the Korean Society of Safety
• /
• v.25 no.6
• /
• pp.86-91
• /
• 2010

The purpose of this study is to analyze the damage patterns and metal structure of 3 phase mold transformers collected from places where accidents have occurred. Compared to an oil-immersed transformer, a mold transformer has the advantage of requiring a smaller installation area and can be kept clean, while its disadvantages include the fact that abnormal symptoms of an accident are difficult to discover and its repair is impossible. The capacity of the mold transformers collected from places where accidents have occurred was 200kVA with primary voltages being F23,900V, R22,900V, 21,900V, 20,900V, 19,900V, etc., as well as secondary voltages being 380V, 220V, etc. It was found from the analysis on the diffusion of combustion in the damaged mold transformers that fire occurred first inside the U-phase primary winding and that carbonization and heat were diffused to V-phase and W-phase in V-pattern. In addition, from the analysis on the cross-sectional structure of the metal of the melted high voltage winding using a metallurgical microscope, it was found that the boundary surface, voids, and columnar structure were formed when an interlayer short-circuit had occurred Therefore, even though it is not possible to find the cause for the occurrence of an interlayer short-circuit at the inner side of the primary winding, it is thought that, due to the thermal energy generated when the short-circuit occurred, the heat source was diffused to the upper side and outside, causing a secondary accident.