• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.4
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• pp.17-24
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• 2006

Hydrodynamic ram of aircraft fuel tanks is one of main ballistic battle damages of an aircraft and has great importance to airframe survivability design. Basic concept, physics and research history of hydrodynamic ram are investigated. The penetration and internal detonation of a simple fuel tank and ICW(Intermediate Complexity Wing) are analyzed by computational method. Structural rupture and fluid burst are analytically realized using general coupling and coupling surface interaction. The results such as fluid pressure, tank stress and displacement are shown and future research chances are suggested based on the study.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.12 no.5
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• pp.57-66
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• 2013

This study investigates structural and vibration analyses due to the change of bolt Numbers on models 1 and 2 of flange couplings connected with both sides of axis. As maximum equivalent stresses of models 1 and 2 are 122.05 and 102.3 MPa respectively by the basis of bolt, these stresses are within the allowable stress of this model and the safety of bolt design is verified. As maximum equivalent stresses of models 1 and 2 are 196.2 and 196.4 MPa respectively by the basis of body, these stresses are within the allowable stress of this model and the safety of body design is verified. Through natural frequency analysis, maximum displacements of model 1 and 2 are shown at the frequencies of 6565.1 and 6614.9 Hz respectively. Maximum displacements in cases of models 1 and 2 are shown at harmonic frequencies of 7760 and 7840 Hz at real loading conditions. By putting these study results together, the durability of vibration at model 2 with bolt numbers of 8 becomes better than model 1 with bolt numbers of 6. These study results can be effectively utilized with the design on flange coupling by anticipating and investigating prevention and durability against its damage.

• The Korean Journal of Applied Statistics
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• v.28 no.5
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• pp.871-883
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• 2015

Vector autoregressive (VAR) models in high dimension suffer from noisy estimates, unstable predictions and hard interpretation. Consequently, the sparse vector autoregressive (sVAR) model, which forces many small coefficients in VAR to exactly zero, has been suggested and proven effective for the modeling of high dimensional time series data. This paper studies coupling measures to select non-zero coefficients in sVAR. The basic idea based on the simulation study reveals that removing the effect of other variables greatly improves the performance of coupling measures. sVAR model coefficients are asymmetric; therefore, asymmetric coupling measures such as Granger causality improve computational costs. We propose two asymmetric coupling measures, filtered-cross-correlation and filtered-Granger-causality, based on the filtered residuals series. Our proposed coupling measures are proven adequate for heavy-tailed and high order sVAR models in the simulation study.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.10a
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• pp.679-680
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• 2012

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.06a
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• pp.823-824
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• 2008

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2010.05a
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• pp.296-297
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• 2010

• Transactions of the Korean Society of Automotive Engineers
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• v.6 no.2
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• pp.21-31
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• 1998

In this paper, a thermo-mechanical model for viscous coupling(VC) was suggested and torque equation in viscous mode was derived considering the effects of geometry of the plates, thermo-mechanical dynamics, silicon oil characteristics and dissolved air characteristics in the silicon oil. Theoretical results were in good accordance with experimental results demonstrating that VC thermo-mechanical model and the theoretical equations, response of the torque transmitted, pressure, temperature and time to the hump were investigated. Simulation results showed that filling rate of the silicon oil plays an integral role not only in the steady state torque characteristics but also in determining the time to hump.

• Journal of the Korean Society for Precision Engineering
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• v.12 no.7
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• pp.107-113
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• 1995

Using the mathematical model of the torsional vibration in spindle system with magnetic coupling, which was proposed in the paper of dynamic analysis of spindle system with magnetic coupling(l), we derive the equations of the motion and the form of the derived equations represents Duffing equation. Numerical analyses are executed in many conditions, namely the various types in magnetic coupling, changes of the gap between driver and follower. To verify the results of the therorectical analyses, a precision dynamic drive system is manufactured and methods of the test to measure the torsional vibration of the spindle system with magnetic coupling are presented ad thests in various conditions are carried out.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.37 no.8
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• pp.57-66
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• 2000

Add-drop filtering effect of a asymmetric fiber-optic coupler ADF(add/drop filter) is analyzed using a new split-step time-domain model. This model is very useful in simulating the devices containing a directional coupler an Bragg gratings, First, a symmetric fiber-optic coupler ADM is analyzed using this model to confirm the accuracy of the new method. Then, an asymmetric fiber-optic coupler ADF is analyzed, and some design parameters for optimal filtering effect is derived.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.19 no.1
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• pp.100-107
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• 2020

As demand for high value-added products with hard materials increases, the line center is used for producing high value-added products in many industries such as aerospace, automobile fields. The line center is a key device for smart factory automation that can improve the production efficiency and the productivity. Therefore, the development of a mill-turn line center is necessary to produce high value-added products with complex shapes flexibly. In the mill-turn process, a milling process and a turning process are combined. In particular, the turning process needs to increase the rigidity of the spindle. The purpose of this study is to analyze the thermal-structural stability through thermo-structural coupled analysis for a mill-turn spindle with a curvic coupling. The maximum temperature and thermal stability of the spindle were analyzed by thermal distribution. In addition, the thermal deformation and thermal-structural stability of the spindle were analyzed through thermo-structural coupled analysis.