• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.1089-1092
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• 1995

A planar vibratory gyroscope using electrostatic actuation and electromagnetic detection is proposed. The gyroscope has large sensitivity and can be fabricated by using surface micrimachining, bulk micromachining and conventional machining technology. In this paper, the gyroscope and the electromagnetic detecting system equations are derived to determine the output characteristics for the planar vibratory gyroscope using electrostatic acturation and electromagnetic detection. The maximum output is obtained when the driving frequencyequals to the detecting frequency. The resonant frequencies of the resonator are determined by the beam stiffness, i.e. the material constants and spring dimensions. The dimensions of the beams are determined using the analytic vibration modelling. The expected resonant frequencies are 200Hz both and the sensitivity is 62mV/deg/sec with 4000 electronic circuit amplifying coefficient for an AC drive voltage of 3V bias voltage of 15V and DC field current of 50 mA.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.3
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• pp.131-137
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• 2003

Proper door effort, required force to open or close a vehicle door, is an essential door design factor for the safety of passengers and pedestrians. Section shape of the door checker arm is the most influential design parameter for achieving a door effort design target. In this research. an analysis procedure to predict door effort using a simplified plane strain finite element model wes investigated for two passenger cars, for which mechanism of checker systems were: different. The variation of checker arm force to be required during moving on arm in opening and closing direction was estimated through analysis, and the result was transformed to the door effort with respect to door opening angle by considering door characteristics. Also, the self·closing force due to door weight was theoretically calculated and added to the door effort from checker arm force. Finally the estimated results of door effort were compared with test results.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.10 no.3
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• pp.67-75
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• 1990

A geometrically nonlinear analysis procedure including the damping effects is presented for the investigation of the dynamic post-divergence and post-flutter behavior of a non-conservative system. The dynamic nonlinear analysis of plane frame structure subjected to conservative and non-conservative forces is carried out by solving the equations of motion using Newmark method. Numerical results are presented to demonstrate the effects of the internal and external damping forces in the conservative and non-conservative systems.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.10 no.3
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• pp.57-65
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• 1990

The finite element menthod for the investigation of the static and dynamic stability of the plane framed structures subjected to non-conservative forces is presented. By using the Hermitian polynomial as the shape function, the geometric stiffness matrix, the load correction stiffness matrix for non-conservative forces, and the matrix equation of internal and external damping are derived. Then, a matrix equation of the motion for the non-conservative system is formulated and the critical divergence and flutter loads are determined from this equation.

• Journal of the Korean Institute of Gas
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• v.11 no.1 s.34
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• pp.34-39
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• 2007

In this paper, the FEM result has been presented for a sealing safety between a valve packing and a valve seat during a open and close operation in a LPG cylinder. The sealing operation of a LPG valve is completed when the valve packing in which is made by a nylon-66 polymer is to stop a LP gas flow, which flows out from the outlet of a brass pipe in a LPG cylinder. The contact sealing mechanism of the valve may be classified by a flat contact of an unused valve packing and a circular groove contact of an used valve packing in a current LPG valve. Based on the FEM and experimental investigations the sealing force, 4.9 MPa for a flat contact mode of the unused valve packing is a little high compared to that of the used valve packing, which shows a circular groove contact geometry against a valve seat. But these sealing pressures for two contact modes are very low compared to the ultimate strenath 83 MPa of the nylon-66 and this may be designed with a excess strength of the valve.

• Journal of the Korean Geotechnical Society
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• v.30 no.1
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• pp.49-63
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• 2014

Bearing capacity factor $N_{\gamma}$ and shape factor were studied for rigid strip and circular footings with a rough base on sand by numerical modelling considering the effect of dilation angle. The numerical model was developed with an explicit finite difference code. Loading procedures and interpretation methods were devised in order to shorten the running time while eliminating the exaggeration of the reaction caused by the explicit scheme. Using the Mohr-Coulomb plasticity model with associated (${\psi}={\phi}$) and nonassociated (${\psi}$ < ${\phi}$) flow-rules, the bearing capacity factor $N_{\gamma}$ was evaluated for various combinations of internal friction angles and dilation angles. Bearing capacity factor decreased as the dilation angle was reduced from the associated condition. An equation applicable to typical sands was proposed to evaluate the relative bearing capacity for the nonassociated condition compared to the associated condition on which most bearing capacity factor equations are based. The shape factor for the circular footing varied substantially when the plane-strain effect was taken into account for the strip footing. The numerical results of this study showed closer trends with the previous experimental results when the internal friction angle was increased for the strip footing. Discussions are made on the reason that previous equations for the shape factor give different results and recommendations are made for the appropriate design shape factor.

• Journal of the Korean GEO-environmental Society
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• v.4 no.4
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• pp.85-96
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• 2003

The Geocell system is the advanced system of Geo-grids, and is one of geosynthetics used for earth reinforcement of weak soil. It is the way to increase earth strength and bearing capacity by using three dimension type of geo-composite. This paper analyzed the bearing capacity mechanism of Geocell system for earth reinforcement. Plate loading tests under the model laboratory condition were performed, and the increase of bearing capacity and the decrease of settlement with shallow foundation were evaluated.

• Journal of the Korea Society of Computer and Information
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• v.19 no.1
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• pp.149-156
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• 2014

NGE(Nested Generalized Exemplar Method) can increase the performance of the noisy data at the same time, can reduce the size of the model. It is the optimal distance-based classification method using a matching rule. NGE cross or overlap hyperrectangles generated in the learning has been noted to inhibit the factors. In this paper, We propose the DHGen(Dominant Hyperrectangle Generation) algorithm which avoids the overlapping and the crossing between hyperrectangles, uses interval weights for mixed hyperrectangles to be splited based on the mutual information. The DHGen improves the classification performance and reduces the number of hyperrectangles by processing the training set in an incremental manner. The proposed DHGen has been successfully shown to exhibit comparable classification performance to k-NN and better result than EACH system which implements the NGE theory using benchmark data sets from UCI Machine Learning Repository.

• Journal of the Korean Society for Railway
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• v.16 no.4
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• pp.311-317
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• 2013

In railway construction, superimposition of horizontal and vertical curves has critical effects on the running stability and the ride comfort of vehicles as well as on construction costs. In this study, running safety, ride comfort, and track acting forces were analyzed by a numerical analysis using the VAMPIRE program according to cases of superimposition of vertical and horizontal curves. From the analysis results, it was found that running safety, riding comfort, and track acting forces in the case of superimposition of vertical and horizontal curves as well as vertical and transition curves meet all of the criteria. Also, in the case of the superimposition of vertical curves and curvature change between horizontal transition curves and circular curves meet all of the criteria.

• Journal of Astronomy and Space Sciences
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• v.22 no.4
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• pp.451-462
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• 2005

Optimal Trajectory Correction Maneuver (TCM) design algorithm has been developed using the B-plane targeting method for future Korean Mars missions. For every-mission phase, trajectory informations can also be obtained using this developed algorithms which are essential to design optimal TCM strategy. The information were computed under minimum requiring perturbations to design Mars missions. Spacecraft can not be reached at designed aim point because of unexpected trajectory errors, caused by many perturbations and errors due to operating impulsive maneuvers during the cruising phase of missions. To maintain spacecraft's appropriate trajectory and deliver it to the designed aim point, B-plane targeting techniques are needed. A software NPSOL is used to solve this optimization problem, with the performance index of minimizing total amount of TCM's magnitude. And also executing time of maneuvers on be controlled for the user defined maneuver number $(1\~5)$ of TCMs. The constraints, the Mars arrival B-plane boundary conditions, are formulated for the problem. Results of this work show the ability to design and analyze overall Mars missions, from the Earth launch phase to Mars arrival phase including capture orbit status for future Korean Mars missions