• Journal of Ocean Engineering and Technology
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• v.18 no.1
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• pp.80-84
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• 2004

The initial hull form of a 3 G/T and 30 knots class coastal leisure boat is newly developed. The performances measured, resistance, trim and sinkage, are investigated in a high-speed, circulating water channel (CWC). The effect of a fin attached on the hull side is studied together. Wave patterns are observed to clarify the relationship between the resistance performance and the wave characteristics. It can be found that the fin plays a role of increasing the resistance performance above a certain velocity.

• Proceedings of the Korean Geotechical Society Conference
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• 2002.10a
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• pp.491-498
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• 2002

The rubble base in the seadike structure is construct with rubble-mound of big size for stability of seadike against a tidal current velocity at the closing. The permeability gives an effect to stability of seadike a lot in The case which rubble base is founded long with a lake direction like objective area of this study. The permeability of the rubble base produced in the model test regarding filling condition and materials of the rubble base, It applied the result which it tests in seepage analysis and it analyzed a stability of piping, In this study, it diminishes the permeability of the rubble base to respect, the pit soil more the dredge soil is effective and it was analyzed with the fact that it increases the stability of lake direction slope against the piping.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.9
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• pp.2373-2384
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• 1996

Connection caching technique is widely used to reduce the overhead incurred by frequency connection establishment in distributed computing environment using connection oriented protocol. We present an efficient connection caching scheme where we divide the system into several host groups and connection between the hosts in the same group is kept prior to others. In other words it makes the connection kept longer by sharing the connection use information between hosts in the same group. Every host group consists of hosts which have heavy intercommunication. And we present performance evaluation of the effect of host grouping upon connection caching and performance comparison of various grouping in several aspects includingmeanservice request interarrival time, mean service time, group size, grouping and type of group. Simulation results show that host grouping is effective in evrey performance criterion and proper grouping of hosts enhances the performance. We also present analysis results for Markov process model of our scheme which are consistent with the simulation results.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.21 no.45
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• pp.319-328
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• 1998

In this paper, the design of ALT(Accelerated Life Test) requires a sampling plan based on failure-censored(Type II censored) ALT with lognormal life distribution. Specially the environmental effect of products has been emphasized, so we considered the upper life limit as well as lower life limit in the ALT sampling plan. The optimal plan with a high stress and a low stress is used as test plan, and the total sample size for test and lot acceptability constant which minimize an asymptotic variance of maximum likelihood estimator of assumed model parameters and satisfy the given producer's risk and customer's risk are drawn out. These values can be acquired by means of the computer program that we coded for resolving the difficulty and complexity of calculation.

• Proceedings of the Safety Management and Science Conference
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• 2004.11a
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• pp.47-51
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• 2004

Facility layout for enterprise's competitive power strengthening and construction of offensive manufacture line and direction presentation for design of production management system that is new by operation improvement according to S company. In enterprise in JIT(Just in Time) system of leading persons affecting in productions among a lot of habitat factor analyze. It is that through equipment Layout among those factors enterprise my problem improve and serves enterprise's absolute ability cultivation. Even if it is JIT production main point that affect to apply the modular production to productive system among at equipment Layout, lot size, bottleneck session etc. worker's multi-function anger, change of demand factor and productive capacity add. 'S' Through enterprise's example, I wish to establish Korean medium and small enterprises' manufacturing industry style equipment Layout model by taken place effect interpretation.

• Journal of Industrial Technology
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• v.18
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• pp.335-341
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• 1998

A numerical investigation was performed to determine the effect of a Gurney flap on a NACA 23012 airfoil. A Navier-Stokes code, RAMPANT, was used to calculate the flow field about airfoil. The fully turbulent results were obtained using the standard $k-{\varepsilon}$ two-equation turbulence model. To provide a check case for our computational method, computations were performed for NACA 4412 airfoil which compared with Wedcock's experimental data. Gurney flap sizes of 0.5, 1.0, 1.5, and 2% of the airfoil chord were studied. The numerical solutions showed the Gurney flap increased both lift and drag. These results suggested that the Gurney flap served to increased the effective camber of the airfoil. But Gurney flap provided a significant increase in lift-to-drag ratio relatively at low angle of attack and for high lift coefficient. Also, it turned out that 0.5% chord size of flap was best one among them.

• Journal of Ship and Ocean Technology
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• v.7 no.3
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• pp.13-33
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• 2003

This paper presents a numerical study on tip vortex cavitation inception predictions based on non-spherical bubble dynamics including splitting and jet noise emission. A brief summary of the numerical method and its validation against a laboratory experiment are presented. The behavior of bubble nuclei is studied in a tip vortex flow field at two Reynolds numbers, provided by a viscous flow solver. The bubble behavior is simulated by an axisymmetric potential flow solver with the effect of surrounding viscous flow taken into account using one way coupling. The effects of bubble nucleus size and Reynolds number are studied. An effort to model the bubble splitting at lower cavitation numbers is also described.

• Journal of the Korea Safety Management & Science
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• v.16 no.2
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• pp.131-138
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• 2014

Auto part industry supplies production for auto manufacturer and after market. These company have inventory for delivery. High inventory level can be good for delivery, but cost will be increase. Low inventory level can be customer unsatisfaction for delivery late. Low inventory level also is reason of low productivity by decreasing product batch size. These article suggest model for calculation a proper inventory level and prove a effect by simulation of some company.

• Journal of Magnetics
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• v.4 no.3
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• pp.84-87
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• 1999

It is shown that progressive crystallization of non-magnetostrictive Co-based metallic glass (VITROVAC 6030) leads to an increase of coercivity by more than three orders of magnitude. The mechani는 responsible for this phenomenon are interpreted showing that the main source for the giant increase of the coercivity is the pinning effect on the domain walls originating from the created crystallites of the size much smaller than the domain width (correlation length for ferromagnetic exchange interactions). It is also shown that gradually devitrified non-magnetostrictive metallic glass is an excellent model material for verification of N el's theory describing the Rayleigh rule.

• Earthquakes and Structures
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• v.2 no.1
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• pp.1-24
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• 2011

During very strong earthquakes, seismically isolated buildings may experience large horizontal relative displacements, which may lead to poundings if an insufficiently wide clearance is provided around the building. This paper investigates, through numerical simulations, the effectiveness of using rubber bumpers, which could be attached at locations where it is likely to have impacts, in order to act as shock-absorbers. For the simulation of the dynamic behavior of such rubber bumpers during impacts, a nonlinear force-based impact model, which takes into account the finite thickness of the rubber bumpers, has been developed. Subsequently, a series of parametric analyses are performed to assess the effect of the gap size, the earthquake characteristics and the thickness, compressive capacity and damping of the bumpers. The stiffness of the moat wall is also parametrically considered during poundings of a seismically isolated building, as another potential mitigation measure for poundings of seismically isolated buildings.