• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.22 no.6
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• pp.901-907
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• 2013

The development of high-rise firefighting vehicles warrants thorough structural analysis for ensuring vehicle stability. A few structural analyses were carried out using CAD data, material properties, load conditions, and boundary conditions for evaluating the structural stability of an overloaded multi-aerial platform for firefighting and rescue. Structural analysis was performed with an analytical model consisting of a turntable, six booms, two jib booms, and a basket structure. This model was operated in eight modes. All simulation was performed using NASTRAN, a commercial code. As a result, we confirm that the position of local stress exceeds that of the yield strength. Therefore, stress concentration relaxation is possible by introducing reinforcing boom structures, changing the shape, or imparting a larger moment of inertia to the booms' cross sections.

• Transactions of the Korean Society of Automotive Engineers
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• v.15 no.5
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• pp.86-96
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• 2007

A direct-injection stratified-charge(DISC) engine has been considered as a promising alternative in spite of high unburned hydrocarbon emission levels during light load operation. In this paper investigation is made to characterize formation and combustion processes of stratified mixture charge in a simple constant volume combustion chamber. Both experimental and numerical analyses are performed for fluid and combustion characteristics with 3 different induction types for rich, homogeneous and lean mixture conditions. The commercial code FIRE is applied to the turbulent combustion process in terms of measured and calculated pressure traces and calculated distributions of mean temperature, OH radical and reaction rate. It turns out that the highest combustion rate occurs for the rich state condition at the spark ignition location due to existence of stoichiometric mixture and timing.

• Advances in Energy Research
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• v.4 no.2
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• pp.163-176
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• 2016

Rapid depletion of fossil based oil, coal and gas reserves and its greater demand day by day necessitates the search for other alternatives. Severe environmental impacts caused by the fossil fire based power plants and the escalating fuel costs are the major challenges faced by the electricity supply industry. Integration of Distributed Generators (DG) especially, wind and solar systems to the grid has been steadily increasing due to the concern of clean environment. This paper focuses on a new simple and fast load flow algorithm named Backward Forward Sweep Algorithm (BFSA) for finding the voltage profile and power losses with the integration of various sizes of DG at different locations. Genetic Algorithm (GA) based BFSA is adopted in finding the optimal location and sizing of DG to attain an improved voltage profile and considerable reduced power loss. Simulation results show that the proposed algorithm is more efficient in finding the optimal location and sizing of DG in 15-bus radial distribution system (RDS).The authenticity of the placement of optimized DG is assured with other DG placement techniques.

• Proceedings of the Korea Concrete Institute Conference
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• 2009.05a
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• pp.477-478
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• 2009

The objective of this study is to increase the insight of the mechanical behaviour of high-strength concrete prepared with fiber reinforcement after exposure to elevated temperatures. In particular, the result of the effects of contents of polypropylene fiber and level of preload on the residual compressive strength, load bearing and stress-strain curve of concrete are discussed

• Proceedings of the Korea Concrete Institute Conference
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• 2003.11a
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• pp.331-334
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• 2003

Since regulation or specification for the reinforcing method are quite ambiguous, structural design for the reinforcement can be subjectively and arbitrarily conducted. Thus, reasonable limitation and guide for the quantity of the reinforcement are required for the safe use of the structure after repair. In order to guarantee the safety of the structural member several items should be considered; reinforcing limit to avoid the brittle failure, least required strength of the existing member before reinforcement in order not to fail under the new serviceability load condition when reinforcing steel plates or CFRP sheets are harmed or subjected to fire.

• Proceedings of the KIEE Conference
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• 1999.07c
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• pp.1373-1375
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• 1999

High impedance fault (HIF) is defined as fault the general overcurrent relay can not detect or interrupt. Especially when HIF occur in residential areas, energized high voltage conductor results in fire hazard, equiment damage or personal threat. This paper proposes the model of HIF in transmission line using the ZnO arrester and resistance to be implemented within EMTP. Wavelet transform is efficient and useful for the detection of HIF in power system, because it uses variable windows according to frequency. HIF detection method using wavelet transform can distinguish HIF from similar phenomena like arcfurance load, capacitor bank switching and line switching.

• Steel and Composite Structures
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• v.22 no.5
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• pp.1141-1162
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• 2016

Concrete-filled double skin steel tube (CFDST) beam-columns are widely used in industrial plants, subways, high-rise buildings and arch bridges. The CFDST columns have the same advantages as traditional CFT members. Moreover, they have lighter weight, higher bending stiffness, better cyclic performance, and have higher fire resistance capacities than their CFT counterparts. The scope of this study is to develop finite element models that can predict accepted capacities of double skin concrete-filled tube columns under the combined effect of axial and bending actions. The analysis results were studied to determine the distribution of stresses among the different components and the effect of the concrete core on the outer and inner steel tube. The developed models are first verified against the available experimental data. Accordingly, an extensive parametric study was performed considering different key factors including load eccentricity, slenderness ratio, concrete compressive strength, and steel tube yield strength. The results of the performed parametric study are intended to supplement the experimental research and examine the accuracy of the available design formulas.

• Proceedings of the KSME Conference
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• 2000.04b
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• pp.879-885
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• 2000

This study is carried out to make clear the reason of occurrence of sudden acceleration incident of AT vehicle. The stepping motor is used to control the engine speed at idle by compensating the volume of air. By the way it's valve is contaminated by blow-by gas, deposit and back fire etc. This contamination could occur the load of motor at low temperature. This plays an important role in damaging the motor's coil with the motor's performance interfered. If it's coil is damaged the ISC could malfunction. If these phenomena occur, the speed of engine may increase or the engine may stall with hunting.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.21 no.6
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• pp.885-891
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• 2012

In this study, some structural analysis using 3D CAD data, material properties, load conditions and boundary conditions are carried out to evaluate structural stability of the multi-aerial platform for high-rise fire fighting and rescue. We conduct structural analysis for the upper structures such as turn table, booms and basket, by using a universal structural analysis program NASTRAN. As the results, there is local stress exceeding the yield strength, but it is able to relax stress concentration in a way such as changing thickness of the structure or making larger inertia moment in cross section of booms.

• Proceedings of the KIEE Conference
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• 2001.07a
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• pp.497-500
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• 2001

Shunt reactors are used to compensate for capacitive VARs generated by lightly loaded transmission lines or underground cables. They are normally connected to the transformer tertiary winding. Dry-type shunt reactors have the advantage compared with oil-immersed shunt reactor as followings. Lower investment and maintenance cost, No fire hazard and no environmental concerns, Simple insulation to ground, Response to transient overvoltage less severe, Linearity of inductance versus load current, Lower-acoustic noise, Easier transport and handling due to lower weight, No oil-collecting system must be provided since there is no oil that can leak into the ground.