• Proceedings of the Korean Geotechical Society Conference
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• 1991.10a
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• pp.179-194
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• 1991

This paper explains outline of a behavior analysis program for underground structures, and its application to a tunnel problem. The program can deal with elasto-plastic behavior of medium and supporting structures, discontinuous behavior due to existing joint, creation and propagation of cracks. in-situ loading condition, and incremental behavior due to stepwise excavation, etc. The program also has additional capabilities such as graphic output of mesh, displacement pattern, stress condition, and safety factor contour, and automatic mesh generation during the excavation steps.

• Smart Structures and Systems
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• v.19 no.2
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• pp.203-211
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• 2017

This paper provides a numerical solution for multiple confocal elliptic dissimilar cylinders. In the problem, the inner elliptic notch is under the traction free condition. The medium is composed of many confocal elliptic dissimilar cylinders. The transfer matrix method is used to study the continuity condition for the stress and displacement along the interfaces. Two cases, or the infinite matrix case and the finite matrix case, are studied in this paper. In the former case, the remote tension is applied in y- direction. In the latter case, the normal loading is applied along the exterior elliptic contour. For two cases, several numerical results are provided.

• 제어로봇시스템학회:학술대회논문집
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• 1993.10a
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• pp.1063-1067
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• 1993

Fuzzy logic is applied to a roll autopilot for missiles. Fuzzy rules are made so that the response duplicates that of the conventional control law for some flight condition. A scaling factor of the fuzzy controller is then scheduled by the missile velocity and altitude information to cope with the variation of the roll dynamics from that flight condition. By computer simulations and calculation of the stability margin, it is shown that the fuzzy control is robuster than the conventional one over the flight envelope even though two control laws work similarly for some flight conditions.

• Communications for Statistical Applications and Methods
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• v.16 no.4
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• pp.639-645
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• 2009

Fractional Brwonian motion(fBm) has properties of behaving tails and exhibiting long memory while remaining Gaussian. In particular, it is well known that interest rates show some long memories and non-Markovian. We present no aribitrage condition for HJM model under the multi-factor fBm reflecting the long range dependence in the interest rate model.

• Journal of applied mathematics & informatics
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• v.41 no.5
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• pp.1071-1084
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• 2023

We consider inviscid, incompressible homogeneous shear flows of variable cross section known as extended Rayleigh problem. For this extended Rayleigh problem, we derived instability region which intersect with semi-circle instability region under some condition. Also we derived condition for stability, upper bound for amplification factor and growth rate of an unstable mode.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.10 no.1
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• pp.113-120
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• 2010

In case the traffic accident occurs, skid mark is very important factor to calculate the car speed. Especially, for the purpose of objective and scientific inspection, traffic accidents should be appraised and inspected by righteous material evidences, computer simulation, and studies such as automobile engineering, traveling and collision accident dynamics, road and traffic engineering. In this paper, it displays the results of studying cases with the reasons of traffic accidents by analyzing and studying automobile kinetics, real traffic accidents and the results of in scientific and objective ways. After computer simulation result that it is proved that compared with unpacked road condition and packed road condition. unpacked road condition is shorter than packed road condition.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1993.10a
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• pp.149-154
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• 1993

In heavy grinding that is on of the high efficient grinding method, meaningful deformation is generated by high temperature. So, after machining, geomeric error generated od the workpiece. The most important factor on the geometric error is temperature difference between upper layer and lower layer (T $_{d}$) . Relations between Td and grinding condition and maximum geometric error and grinding condition are obtained by experiment. This relations are used in fuzzy algorithm for improvement geometric accuracy. The main results are follows : (1) The linear relation between maximum geometric error and grinding condition is ovtained by experiment. (2) The linear relation between maximum temperature difference between upper layer and lower layer and grinding condition is ovtained by experiment. (3) Control peth of wheel for improvement geometric accuracy is obtained by using the fuzzy algorithm.m.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.8
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• pp.1423-1428
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• 2010

The results of off-line and on-line diagnostic tests performed on the stator winding of an air-cooled gas turbine(G/T) generator are reported in this paper. Off-line diagnostic tests included measurements of the ac current, dissipation factor(tan${\delta}$), and partial discharge(PD). Six epoxy-mica capacitors were installed in the three phases of G/T generator for performing on-line diagnostic testing with the turbine generator analyzer(TGA). The TGA showed that the normalized quantity number(NQN) and the PD magnitude($Q_m$) were high in phase A of the stator winding. Internal discharges were generated in phases B and C, and slot discharge occurred in phase A. According to the trend analyses of the NQN and $Q_m$ values available for insulation condition assessment for G/T generator stator windings, it was concluded that phases B and C were in good condition, whereas phase A has been significantly deteriorated.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1998.04a
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• pp.212-217
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• 1998

Reynolds equation, which describes behavior of fluid film in journal bearing, basically satisfies mass conservation. But, boundary conditions usually used with this equation, e.g. half Sommerfeld or Reynolds boundary conditions, cannot fulfill this natural law of conservation. In the case of connecting rod bearing, where applied load is dynamic and its magnitude is relatively large, such unrealistic boundary conditions have serious influence on calculation results, especially on lubricant flow rate or power dissipation which are important parameters in thermal analysis. Another important factor in the analysis of connecting rod bearing is elastic deformation of bearing support structure which is relatively flexible. In this paper, EHL analysis of connecting rod beating is performed using mass-conserving boundary condition. Elastic deformation of bearing support structure and application of mass-conserving boundary condition have significant effects on the performances of connecting rod bearing.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.19 no.9
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• pp.876-883
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• 2009

The radiation of sound from a rectangular plate with a guided edge condition is investigated. By taking this particular boundary condition into account, simple analytical forms of the average radiation efficiency and radiation power based on the modal approach can be found, where the cross-modal terms can average out for all possible point excitation locations. Design variables of the plate such as thickness, aspect ratio, and damping that are closely related to the sound radiation are mainly discussed. The radiation power of the guided plate is found to be governed by the piston mode as well as the critical frequency. While both the radiation efficiency and the radiation power seem to be influenced by thickness and a large aspect ratio, damping loss factor seems less important to the radiation power. It is also shown that no clear corner and edge mode regions may be found for the guided case, unlike the pinned.