• Proceedings of the Korea Concrete Institute Conference
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• 1999.04a
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• pp.525-528
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• 1999

Structural walls have been favored for the design of reinforced concrete buildings in seismic zone areas because they provide an efficient bracing system and offer great potential for lateral load resistance and drift control. Loads on structures due to earthquakes are not unlikely to reach, if not exceed, the design load levels. Hence, structural damage to walls is inevitable, and it is necessary to repair this damaged walls. Yet, information on repair method and data related to the strength and deformation characteristics of repaired walls is limited. In this study, specimens which have their aspect ratios of about 1 to 3 will be repaired. For the repairing the damaged walls, new concrete and new reinforcing bar are replaced with cracked concrete and the buckled reinforcing bar, respectively. The objective of this study is to evaluate the performance of the repaired structural walls in the capacity of strength, stiffness, and maximum deformation comparing with the undamaged walls.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.10a
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• pp.589-594
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• 2000

The necessary strength and ductility to avoid structural damage under moderate earthquake can be achieved by properly detailed transverse reinforcement in the plastic hinge zone. However, most structural walls have a higher aspect ratio(M/Vl\ulcorner) without well confined boundary regions. Therefore there is a need for adequate detailing in the plastic hinge zone, particularly boundary regions. In this paper, the fabricated interlocking spirals is introduced as a new seismic detailing for ductile behavior of the structural walls to be able to substitute for existing complicated detailing with ties. This paper also investigates the behavior characteristics of structural walls with interlocking spirals including confinement of the concrete and strength associated with flexure and shear.

• Proceedings of the KIEE Conference
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• 2001.05a
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• pp.316-318
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• 2001

Occasionally, equipment in a distribution system fails due to damage from weather, vandalism, or other causes. In addition, it is recommended practice to have some way in which maintenance or replacement of every element in a system can be performed without causing lengthy interruption of electrical service to the customers it feeds. Thus, alternate sources, paths, and configurations of service must be planned so that both failures and maintenance do not affect customer service beyond a reasonable amount. In some cases, planning for alternate routes of service during equipment outages or emergencies -- will be the major aspect influencing selection of a feeder's capacity, type of route, or layout. We want to know the relationship between molt-dividing multi-connection and distribution reliability for contingency support considerations.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.7 no.4
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• pp.42-49
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• 1998

This wear debris can be harvested from the lubricants of operating machinery and its morphology is directly related to the damage to the interacting surface from which the particles originated. The morphological identification of wear debris can therefore provide very early detection of a fault and can also often facilitate a diagnosis. The purpose of this study is to attempt the developement of intelligent system for moving condition diagnosis of the machine driving system. The four shape parameter(50% volumetric diameter, aspect, roundness and reflectivity) of war debris are used as inputs to the neural network and learned the moving condition of five values(material3, applied load 1, sliding distance 1). It is shown that identification results depend on the ranges of these shape parameter learned. The three kinds of the wear debris had a different pattern characteristics and recognized the moving condition and materials very well by neural network.

• Ocean Systems Engineering
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• v.1 no.2
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• pp.111-119
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• 2011

Mines, torpedoes and improvised explosive devices (IED) pose a serious threat to the survivability of naval combatants. Inasmuch, a major goal in the design of modern combatant ships has been to eliminate or at least reduce the devastating damage caused by underwater explosion events. Even though there has been extensive research performed on the various underwater explosion phenomena and their associated effects, effective shock testing and shock proofing strategies for naval ship systems have proven to be illusive. Through the use of modeling and simulation (M&S), live fire test and evaluation (LFT&E) and laboratory testing, general guidelines for the shock hardening of shipboard equipment and systems have been developed. In this paper, current aspect of ship survivability has been addressed and future direction is discussed.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1997.10a
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• pp.135-144
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• 1997

This wear debris can be harvested from the lubricants of operating machinery and its morphology is directly related to the damage to the interacting surfaces from which the particles originated. The morphologies of the wear particles are therefore directly indica- rive of wear processes occuring in machinery and their severity. The neural network was applied to identify wear debris generated from the lubricated moving system. The four parameter(50% volumetric diameter, aspect, roundness and reflectivity) of wear debris are used as inputs to the network and learned the friction condition of five values(material 3, applied load 1, sliding distance 1). It is shown that identification results depend on the ranges of these shape parameter learned. The three kinds of the wear debris had a different pattern characteristic and recognized the friction condition and materials very well by neural network. We dicuss how the network determines difference in wear debris feature, and this approach can be applied to condition diagnosis of the lubricated moving system.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.05a
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• pp.505-511
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• 2003

Experimental investigation was conducted into the flexure/shear-critical behavior of earthquake-damaged reinforced concrete columns with lap splicing of longitudinal reinforcement in the plastic hinge region. Six test specimens in the aspect ratio of 2,5 were made with test parameters: confinement ratios, lap splices, and retrofitting FRP materials. They were damaged under series of artificial earthquakes of which magnitude could be compatible in Korean peninsula. Directly after the pseudo-dynamic test, damaged columns were retested under inelastic reversal cyclic loading simultaneously under a constant axial load, P=$0.1f_{ck}A_g. Residual seismic performance of damaged columns was evaluated and compared to that of the corresponding original columns. Test results show that RC bridge piers with lap-spliced longitudinal steels in the plastic hinge region appeared to fail at low ductility. This was due to the debonding of the lap splice, which resulted from insufficient development of the longitudinal steels. The specimens externally wrapped with composite FRP straps in the potential plastic hinge region indicated significant improvement both in flexural strength and displacement ductility, and strain energy ductility.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2001.11a
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• pp.98-104
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• 2001

Recently, the researches on the prevention of marine oil pollution being strengthened. Sludge oils were unavoidably produced in ship's operations, therefore it is necessary to manage the sludge oils inside the ship itself with the view to prevent marine oil pollution from ship. The present study deals with the ultrasonic breaking systems that recycle the sludge oil from ships into usable oil to be burnt. At the first instanceexperimental studies were carried out to investigate the homogenizing effect of the marine oils and the erosion aspect of horn disc by repeated vibration of ultrasonic transducer. The erosion damages for horn disc SS41 steel with weight loss rate and the irradiation time to max. erosion rate were examined according to the variation of the transducer amplitude, the oil temperature and the immersing depth of horn disc. As the result of it, the erosion aspects of horn disk were varied with oil environments and testing time.

• Journal of Advanced Marine Engineering and Technology
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• v.23 no.1
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• pp.79-87
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• 1999

The most part of the faculty drop a trouble and damage of machine equipment even if whatever cause they break out take place at local and trifling place and the factor dominating their trouble is due to wear debris occurred in the lubricated machine moving surface. This study has been car-ried out to identify morphology of wear debris on the lubricated machine moving system by means of computer image analysis. Namely the wear debris contained in lubricating oil extracted from movable machine equipment will be filtered through membrane filter(void diameter 0.45${\mu}m$) and will be analyzed with its data information such as 50% volume diameter aspect roundness and reflectivity. Morphological characteristic of wear debris is easily distinguished by four shape parameters it is necessary to divide small class of every 100 wear debris in total wear particles in order to distinguish morphological characteristic of wear debris more easily by computer image analysis. We are sure that operation condition diagnosis of the lubricated machine moving surfaces is possible by computer image analysis.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2008.04a
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• pp.321-324
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• 2008

Forest fire danger rate of thinning area was lower than that of non thinning area, because height rate of leewardside in burned stem of tree, damage rate of crown and mortality of tree in thinning area were 30.8%, 37% and 48.4% lower than that in non-thinning area, respectively. Intensity of forest fire varied depending upon topographical condition up slope, down slope, aspect, location as well as species, breast height diameter and forest tree density. Especially, a mountaintop area was burned down when forest fire was spread to up slope ridge of mountain.